Patent Application
20150165244
Embodiments of the present invention relate generally to treatment of tissue by application of energy thereto, and particularly to ablation of cardiac or other tissue by application of ultrasound energy.
Atrial fibrillation is a common cardiac arrhythmia involving the atria of the heart. During atrial fibrillation, the atria beat irregularly and out of coordination with the ventricles of the heart. Atrial fibrillation disrupts efficient beating of the heart and may result in blood clotting in the atrium leading to serious medical conditions such as strokes.
Atrial fibrillation is generally caused by abnormal electrical activity in the heart. During atrial fibrillation, electrical discharges may be generated by parts of the atria which do not normally generate electrical discharges, such as pulmonary vein ostia in the atrium. Pulmonary vein isolation is a common medical procedure for treatment of atrial fibrillation.
Ablation technologies currently include unipolar and bipolar techniques. The unipolar techniques employ various energy sources, including radiofrequency (RF), microwave, high intensity focused ultrasound (HIFU), laser, and cryogenic energy sources. The bipolar techniques employ RF energy.
For some applications, an ultrasound transducer is placed on a first side of the target tissue and applies the ultrasound energy to the target tissue. Typically, at least part of the ultrasound energy passes entirely through the target tissue. A reflective region is provided on a second side of the target tissue from the transducer, by a reflection-facilitation element. The reflective region reflects at least part of ultrasound energy that passes through the target tissue, and thereby protects proximate tissues on the second side of the target tissue by inhibiting the energy from continuing into those tissues.
The target tissue absorbs at least part of the energy that arrives directly from the transducer, and at least part of the energy that is reflected by the reflective region. Thereby, as well as protecting proximate tissues on the second side of the target tissue, the presence of the reflective region increases the amount of energy available to be absorbed by the target tissue, resulting in temperature elevation and enhanced ablation of the target tissue. Reflection of the ultrasound energy such that it passes through the tissue for a second time achieves what may be considered a bipolar effect.
Thereby, providing a reflective region (e.g., by using a reflection-facilitation element) on the other side of the target tissue to an ultrasound transducer, typically increases the efficacy and/or safety of ultrasound-based ablation. For some applications of the invention, the target tissue includes cardiac tissue, the transducer is disposed in a chamber of the heart, and the reflective region is provided in the pericardial cavity (or vice versa).
For some applications of the invention, the reflection-facilitation element comprises an inflatable reflection-facilitation element, configured to provide the reflective region by being inflated with a fluid (typically a gas) that has an acoustic impedance that is different from that of the target tissue, and thereby reflects ultrasound that arrives at the gas via the target tissue. For some applications, the reflection-facilitation element comprises an introducer, configured to provide the reflective region by delivering free gas to the second side of the target tissue (e.g., to the pericardial cavity). For some applications, more than one reflective region is provided, and/or more than one reflection-facilitation element is used. For example, two inflatable reflection-facilitation elements may be used (e.g., one in the pericardial cavity, and one in a heart chamber), or free gas may be used in addition to an inflatable reflection-facilitation element.
For some applications, an inflatable reflection-facilitation element is configured to facilitate delivery and/or control of the free gas. For example, the inflatable reflection-facilitation element may be disposed in the pericardial cavity, in and/or around a portion of the heart, and configured to trap the free gas, and/or to inhibit displacement of the free gas. For some applications, an inflatable reflection-facilitation element comprises an outlet, configured to facilitate delivery of free gas, such as to a site distal to the inflatable reflection-facilitation element.
For some applications, one or more restricting elements (e.g., adjustable restricting elements) are provided to limit and/or control expansion of an inflatable reflection-facilitation element, or a portion thereof, in one or more respective given dimensions.
For some applications, a transducer is provided that is configured to apply ultrasound energy in a non-circular 360-degree focal pattern. For some such applications, the transducer is configured, and used, to generate an annular lesion while the transducer is disposed at a site that is not at the center of the lesion. For example, an annular lesion that circumscribes two pulmonary vein ostia, may be made in a left atrial wall while the transducer is disposed in the vicinity of one of the pulmonary vein ostia.
For some applications, magnetic coupling between the ultrasound transducer and a reflection-facilitation element is used to facilitate ablation, e.g., to facilitate positioning of the reflection-facilitation element with respect to the ultrasound transducer. For some applications, magnetic coupling is used between the reflection-facilitation element and a guiding member, e.g., to facilitate positioning of the reflection-facilitation element.
For some applications, a ultrasound transducer unit is configured (1) to detect anatomy and/or a reflection-facilitation element, and (2) to subsequently ablate tissue at least in part responsively to the detected anatomy and/or reflection-facilitation element.
For some applications, an ultrasound transducer unit comprises first and second ultrasound transducers, each configured to apply ultrasound energy radially in 180 degrees, and fixedly coupled to each other such that the transducer unit is configured to apply ultrasound energy radially in 360 degrees.
For some applications, an inflatable element is provided, that is configured to conduct ultrasound energy from the ultrasound transducer to the target tissue.
For some applications, a camera is used to facilitate ablation of the target tissue, by facilitating navigation, and/or by detecting changes in the tissue indicative of a degree of ablation.
For some applications, an inflatable, tissue-separating element is provided, to facilitate blunt dissection.
For some applications, a pericardial access tool is provided, comprising a helical needle, and a sensor, configured to sense the location of the tool with respect to tissue being penetrated.
For some applications, techniques described herein are practiced in combination with techniques described in one or more of the references cited in the Cross-references section of the present patent application.
There is therefore provided, in accordance with an application of the present invention, apparatus for ablating tissue of a subject, the apparatus including:
a reflection-facilitation element:
an ultrasound tool, including at least one ultrasound transducer, configured to be placed at a second side of the tissue of the subject, and to apply ultrasound energy such that at least a portion of the applied energy is reflected by the fluid.
There is further provided, in accordance with an application of the present invention, apparatus for reflecting ultrasound in a subject, the apparatus including a reflection-facilitation element, including:
an inflatable element, configured to be placed at an anatomical site of the subject; and
an introducer, including at least one tubular element, coupled to the inflatable element,
the reflection-facilitation element being configured to deliver a fluid to the anatomical site of the subject, such that a portion of the fluid is disposed within the inflatable element, and another portion of the fluid is disposed outside of the inflatable element.
There is further provided, in accordance with an application of the present invention, a method for ablating tissue of a subject, the method including:
delivering an inflatable element to a first side of the tissue of a subject;
delivering a fluid to the first side of the tissue of the subject, such that:
placing an ultrasound transducer at a second side of the tissue of the subject; and
activating the ultrasound transducer to apply ultrasound energy through the tissue of the subject, such that at least part of the ultrasound energy is reflected by the fluid.
In an application, delivering the fluid includes delivering the fluid such that at least part of the second portion of the fluid is in contact with an outer surface of the inflatable element.
There is further provided, in accordance with an application of the present invention, a method for reflecting ultrasound energy in a subject, the method including providing a reflective region at the anatomical site by:
delivering an inflatable element to an anatomical site of the subject;
subsequently inflating the inflatable element with a first portion of a fluid; and
delivering a second portion of the fluid to the anatomical site of the subject, such that at least part of the second portion of the fluid is in contact with an outer surface of the inflatable element.
There is further provided, in accordance with an application of the present invention, a method for ablating myocardial tissue of a subject, the method including:
delivering an inflatable element to a pericardial cavity of the subject;
inflating the inflatable element;
delivering a fluid to a site that is within the pericardial cavity and outside of the inflatable element;
placing an ultrasound transducer in a heart chamber of a subject; and
activating the ultrasound transducer.
There is further provided, in accordance with an application of the present invention, apparatus for ablating tissue circumscribing an ostium of vasculature of a subject, the apparatus including:
a reflection-facilitation element; and
an ultrasound transducer:
In an application:
the ostium includes an ostium of a pulmonary vein of the subject into a left atrium of the subject,
the reflection-facilitation element is configured to be disposed in the pulmonary vein of the subject, and
the ultrasound transducer is configured to be placed in the atrium of the subject.
In an application:
the ostium includes an ostium of a pulmonary vein of the subject into a left atrium of the subject,
the reflection-facilitation element is configured to be disposed in the atrium of the subject, and
the ultrasound transducer is configured to be placed in the pulmonary vein of the subject.
In an application, the reflection-facilitation element includes an inflatable element.
In an application, the reflection-facilitation element includes a metal.
In an application, the reflection-facilitation element is annular.
In an application, the ultrasound transducer is annular.
In an application, the reflection-facilitation element is dimensioned to facilitate positioning of the ultrasound transducer on the second side of the ostium.
There is further provided, in accordance with an application of the present invention, apparatus for ablating tissue of a heart of a subject, the heart being enclosed by a pericardium of the subject, and including cardiac tissue that defines a left atrium, the left atrium being in fluid communication with four pulmonary veins of the subject via four respective pulmonary vein ostia of the subject, the pericardium defining a pericardial cavity, the apparatus including:
an elongate member:
a reflection-facilitation element, configured to be disposed at a first side of the cardiac tissue; and
at least one ultrasound transducer, configured to be disposed at a second side of the cardiac tissue, and to intracorporeally apply ultrasound energy such that at least part of the energy is intracorporeally reflected by the reflection-facilitation element.
In an application, the apparatus is configured to ablate only tissue that is disposed directly between the reflection-facilitation element and the ultrasound transducer.
In an application, the elongate member is configured to be delivered to the pericardial cavity percutaneously.
In an application, the ultrasound transducer is configured to be transluminally delivered to the left atrium of the subject.
In an application, the reflection-facilitation element is configured to be transluminally delivered to the left atrium of the subject.
In an application, the ultrasound transducer is configured to be magnetically coupled to the reflection-facilitation element.
In an application, the elongate member includes the ultrasound transducer.
In an application, the elongate member is shaped to define an elongate chamber, and the ultrasound transducer is disposed within, and slidable through, the elongate chamber.
In an application, the at least one ultrasound transducer includes a plurality of ultrasound transducers, disposed along at least part of the longitudinal axis of the elongate member.
In an application, the elongate member is shaped to define an elongate chamber.
In an application, the elongate chamber includes the reflection-facilitation element.
In an application, the ultrasound transducer is disposed within, and slidable through, the elongate member.
There is further provided, in accordance with an application of the present invention, apparatus for ablating tissue of a subject, the apparatus including:
a reflection-facilitation element, configured to be placed on a first side of the tissue of the subject; and
an ultrasound transducer unit, configured to be placed on a second side of the tissue of the subject, magnetically couplable to the reflection-facilitation element, and configured to apply ultrasound energy such that at least part of the ultrasound energy is reflected by the reflection-facilitation element.
In an application:
the reflection-facilitation element includes:
In an application, the ultrasound transducer applies the ultrasound in a sound field, and the apparatus is configured such that the magnetic coupling of the first and second annular magnetically-attractable elements facilitate the reflection of the at least part of the ultrasound energy by the reflector, by positioning the reflector in the sound field.
There is further provided, in accordance with an application of the present invention, apparatus for facilitating ablation of tissue of a subject, the apparatus including:
a transducer unit, including a plurality of ultrasound transducers;
a control unit, configured:
In an application, the at least one echo includes at least one echo of the first application that is reflected by the tissue of the subject, and the control unit is configured to drive the ultrasound transducers at least in part responsively to the at least one echo of the first application that is reflected by the tissue of the subject.
In an application:
the transducer unit is configured to be placed on a first side of the tissue of the subject,
the apparatus further includes a reflection-facilitation element, configured to be placed on a second side of the tissue of the subject, and
the at least one echo includes at least one echo of the first application that is reflected by the reflection-facilitation element, and the control unit is configured to drive the ultrasound transducers at least in part responsively to the at least one echo of the first application that is reflected by the reflection-facilitation element.
In an application, the plurality of ultrasound transducers are disposed in a three-dimensional array.
In an application, the control unit includes an intracorporeal control unit, fixedly coupled to the transducer unit.
In an application, the control unit includes an extracorporeal control unit.
In an application, the transducer unit is configured to receive the at least one echo, and to generate the signal indicative of the at least one echo.
In an application, each ultrasound transducer includes an ultrasound transceiver, and is configured to receive the at least one echo.
In an application, the apparatus further includes a mapping unit, configured to generate a map of at least the tissue of the subject in response to receiving the at least one echo.
In an application, the control unit includes the mapping unit.
In an application, the map includes a virtual map
In an application, the control unit is configured to drive the ultrasound transducers automatically in response to the map.
In an application, the apparatus further includes an extracorporeal display, and the mapping unit is configured to drive the display to graphically display the map.
In an application, the mapping unit is configured to generate the map such that the map includes the reflection-facilitation element.
There is further provided, in accordance with an application of the present invention, apparatus for applying ultrasound, the apparatus including:
a transducer unit, including:
In an application, the first ultrasound transducer is configured to apply ultrasound energy that has a first frequency, and the second ultrasound transducer is configured to apply ultrasound energy that has a second frequency that is different to the first frequency.
In an application, the transducer unit is configured to apply ultrasound energy using the first ultrasound transducer independently of the second transducer.
In an application, the first ultrasound transducer has a first focal length, and the second ultrasound transducer has a second focal length that is different from the first focal length.
There is further provided, in accordance with an application of the present invention, apparatus for ablating tissue of a body of a subject, the apparatus including:
an ultrasound transducer, configured to apply ultrasound energy to the tissue of the subject; and
a camera unit, coupled to the ultrasound transducer, and including a camera, configured to acquire at least one image of the tissue, that is indicative of a degree of ablation of the tissue.
In an application, the transducer has a longitudinal axis, and has a focal point that is disposed generally radially outward from midway along the longitudinal axis of the transducer.
In an application, the transducer has a longitudinal axis, and the camera unit is disposed generally midway along the longitudinal axis of the transducer.
In an application, the transducer has a focal point, and the camera unit is coupled to the transducer such that the camera faces the focal point of the transducer.
In an application, the body of the subject includes a fluid of the subject, and the apparatus further includes a transparent element, configured to exclude the fluid from an area between the camera and the focal point.
In an application, the camera unit includes a movable mount, configured to facilitate movement of the camera with respect to the transducer.
In an application, the movable mount includes a rotatable ring, configured to facilitate revolving of the camera around the longitudinal axis of the transducer.
There is further provided, in accordance with an application of the present invention, apparatus for ablating tissue of a wall of a left atrium of a heart of a subject, the apparatus including:
an inflatable element; and
an ultrasound transducer, disposed within the inflatable element, and configured to apply ultrasound energy to the wall of the atrium of the subject,
the apparatus being configured to be delivered to the left atrium of the subject, and the inflatable element being configured, when inflated:
In an application, the apparatus further includes a liquid, wherein:
the inflatable element is configured to be inflated with the liquid, and
the liquid is configured to conduct the ultrasound energy from the transducer to the wall of the atrium of the subject.
In an application, the liquid is acoustically transparent.
In an application, the liquid is optically transparent.
In an application, the apparatus further includes a camera unit:
including a camera,
coupled to the transducer,
disposed within the inflatable element, and
configured to acquire at least one image of the tissue, that is indicative of a degree of ablation of the tissue.
In an application, the transducer has a focal point, and the camera unit is coupled to the transducer such that the camera faces the focal point of the transducer.
In an application, the heart of the subject contains a fluid of the subject, and the inflatable element is configured to exclude the fluid from an area between the camera and the focal point.
In an application, the inflatable element is configured, when inflated, to temporarily reshape the wall of the atrium of the subject.
In an application:
the ultrasound transducer has a focal pattern that has a shape,
the wall of the atrium of the subject has a cross-sectional shape, and
the inflatable element is configured, when inflated, to temporarily reshape the wall of the atrium of the subject such that the cross-sectional shape of the wall becomes more similar to the shape of the focal pattern than when the inflatable element is not inflated.
There is further provided, in accordance with an application of the present invention, apparatus for use with a vena cava of a subject and a right atrium of the subject, the apparatus including a tubular inflatable element, the inflatable element being configured to be transluminally delivered to the vena cava, and to be inflated within the vena cava, and when inflated within the vena cava:
being shaped to define a longitudinal lumen therethrough, and being configured:
In an application, the apparatus further includes an ultrasound transducer, configured to intracorporeally apply ultrasound energy such that at least part of the ultrasound energy reaches the inflatable element, and the inflatable element is configured to reflect at least a part of the ultrasound energy that reaches the inflatable element.
In an application:
the vena cava includes a superior vena cava of the subject and an inferior vena cava of the subject, and
the inflatable element, when inflated within the superior vena cava and the inferior vena cava:
There is further provided, in accordance with an application of the present invention, apparatus for use in a pericardial cavity proximate to a heart of a subject, and for use with an ultrasound transducer, configured to be placed on a first side of a tissue of a subject, and to apply ultrasound energy to the tissue of the subject, the apparatus including a reflection-facilitation element, the reflection-facilitation element:
configured to be disposed in the pericardial cavity of the subject and on a second side of the tissue of the subject,
including an inflatable member, having a first side and a second side, and configured to be inflated while the reflection-facilitation element is disposed in the pericardial cavity of the subject, and
including a first electrode, disposed on the first side of the inflatable member and a second electrode, wiredly coupled to the first electrode, the first and second electrodes being configured to facilitate defibrillation of the heart of the subject,
the ultrasound transducer being configured to apply the ultrasound energy such that at least a portion of the energy reaches the inflatable member, and the inflatable member being configured to reflect at least a portion of the ultrasound energy that reaches the inflatable member.
In an application, the second electrode is disposed on the second side of the inflatable member, and the first and second electrodes are configured to conduct electricity from the first side to the second side of the inflatable member.
In an application, the second electrode is disposed on the first side of the inflatable member, and the first and second electrodes are configured to be driven to apply a defibrillating current to the heart of the subject.
In an application, the apparatus further includes a control unit, configured to drive the first and second electrodes to apply the defibrillating current to the heart of the subject.
There is further provided, in accordance with an application of the present invention, apparatus for use in a vicinity of a pericardial cavity of a body of a subject, the body of the subject including at least one body lumen, the apparatus including:
a reflection-facilitation element, including a magnetically-attractable element, and configured:
a magnetic guiding member, configured to be delivered to the body lumen, and to magnetically move the reflection-facilitation element from within the body lumen, and without touching the reflection-facilitation element.
In an application, the magnetic guiding member is configured to be moved within the body lumen, and to magnetically move the reflection-facilitation element when the magnetic guiding member is moved within the body lumen.
In an application, the magnetic guiding member includes an electromagnet.
In an application, the body lumen includes a blood vessel of the subject, and the magnetic guiding member is configured to be transluminally delivered to the blood vessel of the subject, and to magnetically move the reflection-facilitation element from within the blood vessel of the subject.
In an application, the body lumen includes a vena cava of the subject, and the magnetic guiding member is configured to be transluminally delivered to the vena cava of the subject, and to magnetically move the reflection-facilitation element from within the vena cava of the subject.
In an application, the body lumen includes an aorta of the subject, and the magnetic guiding member is configured to be transluminally delivered to the aorta of the subject, and to magnetically move the reflection-facilitation element from within the aorta of the subject.
In an application, the body lumen includes a lumen of the gastrointestinal system of the subject, and the magnetic guiding member is configured to be transluminally delivered to the lumen of the gastrointestinal system of the subject, and to magnetically move the reflection-facilitation element from within the lumen of the gastrointestinal system of the subject.
In an application, the body lumen includes an esophagus of the subject, and the magnetic guiding member is configured to be transluminally delivered to the esophagus of the subject, and to magnetically move the reflection-facilitation element from within the esophagus of the subject.
There is further provided, in accordance with an application of the present invention, apparatus for use with a pericardial cavity proximate to a heart of a subject, the apparatus including a reflection-facilitation element, the reflection-facilitation element including:
a longitudinal inflatable member, configured:
In an application, the reflection-facilitation element is configured to facilitate provision of a reflective region within the first portion of the pericardial cavity of the subject.
In an application, the reflection-facilitation element is configured to facilitate provision, within the pericardial cavity of the subject, of a reflective region for ultrasound.
In an application, the longitudinal inflatable member has a first end, and a second end that is magnetically couplable to the first end.
In an application, at least the first end of the longitudinal inflatable member is coupled to an electromagnet.
There is further provided, in accordance with an application of the present invention, apparatus for separating a first tissue of a subject from a second tissue of a subject, the apparatus including an inflatable element, the inflatable element:
having an outer surface that includes a hydrophobic material,
having an inflated state in which the inflatable member has a distal portion,
having a deflated state in which:
being configured to be inflated from the deflated state to the inflated state.
In an application, the inflatable element is configured:
to be placed, in the deflated state, against the first and second tissues such that the first portion outside the concavity is held against the first tissue, and the second portion outside the concavity is held against the second tissue, and
such that, when the first portion is held against the first tissue, the second portion is held against the second tissue, and the inflatable element is inflated, the distal end moves between the first tissue and the second tissue.
In an application, when the first portion is held against the first tissue, the second portion is held against the second tissue, and the inflatable element is inflated, the inflatable element increases a distance between the first tissue and second tissue.
In an application, the apparatus further includes an ultrasound transducer, configured to intracorporeally apply ultrasound energy such that at least part of the ultrasound energy reaches the inflatable element, and the inflatable element is configured to reflect at least a part of the ultrasound energy that reaches the inflatable element.
There is further provided, in accordance with an application of the present invention, apparatus for use with a tissue of a subject, the apparatus including:
a needle, shaped to define a helix that defines a space along the longitudinal axis thereof, and configured to penetrate the tissue by being rotated around the longitudinal axis;
a sensor, disposed within the space defined by the helix defined by the needle, and configured to detect a position of at least the sensor with respect to the tissue.
In an application, the sensor is configured to detect a position of at least the sensor with respect to the tissue, by detecting light that is indicative of the position.
In an application, the sensor is configured to detect a position of at least the sensor with respect to the tissue, be detecting electrical impedance indicative of the position.
In an application:
the sensor is configured to generate a signal indicative of the position of at least the sensor with respect to the tissue, and
the apparatus further includes a control unit, configured to receive the signal.
In an application, the control unit is configured to display information indicative of the position of at least the sensor with respect to the tissue.
In an application, the control unit is configured to drive the needle to rotate.
In an application, the control unit is configured to automatically stop the needle from rotating, at least in part responsively to receiving the signal.
In an application, the sensor is configured to detect a position of at least the sensor with respect to the tissue, be detecting ultrasound energy indicative of the position.
In an application, the sensor includes an ultrasound transceiver.
There is further provided, in accordance with an application of the present invention, apparatus for use within a pericardial cavity of a subject, the apparatus including:
an inflatable portion, configured to be disposed within the pericardial cavity;
an inflation tube, in fluid communication with the inflatable portion, and configured to facilitate inflation of the inflatable portion; and
at least one adjustable restricting element, coupled to the inflatable portion, and configured:
In an application, the apparatus further includes an ultrasound transducer, configured to intracorporeally apply ultrasound energy such that at least part of the ultrasound energy reaches the inflatable portion, and the inflatable portion is configured to reflect at least a part of the ultrasound energy that reaches the inflatable portion.
In an application, the at least one adjustable restricting element includes a plurality of adjustable restricting elements, each adjustable restricting element being configured:
to limit a maximum length of the inflatable portion in a respective dimension, and
while the inflatable portion is disposed within the pericardial cavity, to change the maximum length of the inflatable portion in the respective dimension.
In an application, the inflatable portion defines an inner surface and at least one coupling site on the inner surface, and the adjustable restricting element includes a longitudinal member that is coupled to the at least one coupling site on the inner surface of the inflatable portion, and extends to outside of the inflatable portion.
In an application:
the inflatable portion defines a plurality of coupling sites,
the longitudinal member is slidably coupled to at least one of the coupling sites, and
the apparatus is configured such that increasing tension on the longitudinal member reduces a maximum distance between the coupling sites.
There is further provided, in accordance with an application of the present invention, apparatus for applying ultrasound to a wall of a left atrium of a subject, in a vicinity of at least a first pulmonary vein ostium and a second pulmonary vein ostium of the subject, the apparatus including:
an ultrasound transducer, configured:
a guiding element, configured to be placed within the first pulmonary vein ostium, and to stabilize the transducer in the vicinity of the first pulmonary vein ostium.
In an application, the apparatus is configured such that, when the ultrasound transducer is stabilized in the vicinity of the pulmonary vein ostium, the ultrasound transducer is configured to ablate an annular lesion in the wall of the left atrium, the lesion circumscribing the first and second pulmonary vein ostia.
In an application, the ultrasound transducer includes a phased array of ultrasound transducers.
In an application, the ultrasound transducer is configured to generate an annular lesion in the wall of the left atrium while disposed at a site that is not equidistant from all parts of the lesion.
In an application, the ultrasound transducer is generally hourglass-shaped and rotationally asymmetric.
In an application, the ultrasound transducer has a circumferential lateral surface that is concave, and the concavity of the lateral surface has a depth that progressively changes around the lateral surface.
There is further provided, in accordance with an application of the present invention, a method for applying ultrasound to a wall of a left atrium of a subject, in a vicinity of at least a first pulmonary vein ostium and a second pulmonary vein ostium of the subject, the method including:
advancing an ultrasound transducer into the left atrium of the subject, and into the vicinity of the first pulmonary vein ostium, the ultrasound transducer being configured to apply ultrasound energy that has a non-circular, 360-degree focal pattern;
stabilizing the ultrasound transducer in the vicinity of the first pulmonary vein ostium by advancing a guiding element, coupled to the ultrasound transducer, into the first pulmonary vein ostium; and
ablating, in the wall of the left atrium, an annular lesion that circumscribes the first pulmonary vein ostium and the second pulmonary vein ostium, by driving the ultrasound transducer to apply the ultrasound energy in the non-circular, 360-degree focal pattern.
In an application, ablating the annular lesion includes ablating the annular lesion by driving the ultrasound transducer to apply the ultrasound energy while the ultrasound transducer is disposed at a site that is not equidistant from all parts of the lesion.
For some applications, techniques described herein are practiced in combination with techniques described in one or more of the references cited in the Background section and Cross-references section of the present patent application.
The present invention will be more fully understood from the following detailed description of applications thereof, taken together with the drawings, in which:
Ultrasound ablation of tissue involves delivering ultrasound energy that directly heats the tissue in the acoustic focal volume (e.g., the target tissue). As with other ablation techniques, it is important to avoid inadvertently damaging other tissues, such as those adjacent to the target tissue. For example, when ablating tissue of the left atrium of a subject (e.g., to treat atrial fibrillation), it is important to avoid inadvertently damaging the nearby esophagus, as well as other adjacent tissues.
An ultrasound transducer is placed on a first side of the target tissue and applies the ultrasound energy to the target tissue. Typically, at least part of the ultrasound energy passes entirely through the target tissue. A reflective region is provided on a second side of the target tissue from the transducer, by a reflection-facilitation element. The reflective region reflects at least part of ultrasound energy that passes through the target tissue, and thereby protects proximate tissues on the second side of the target tissue by inhibiting the energy from continuing into those tissues.
The target tissue absorbs at least part of the energy that arrives directly from the transducer, and at least part of the energy that is reflected by the reflective region. Thereby, as well as protecting proximate tissues on the second side of the target tissue, the presence of the reflective region increases the amount of energy available to be absorbed by the target tissue, resulting in temperature elevation and enhanced ablation of the target tissue. Reflection of the ultrasound energy such that it passes through the tissue for a second time achieves what may be considered a bipolar effect.
For some of the applications described herein, a reflection-facilitation element is used to provide a reflective region by delivering free gas to the second side of the target tissue. For example, the reflection-facilitation element comprises an introducer, such as a needle and/or a tube. The free gas has an acoustic impedance that is different to that of the surrounding tissue (e.g., the target tissue), and thereby reflects at least some of the ultrasound energy that passes through the target tissue, back through the target tissue.
For some of the applications described herein, a reflection-facilitation element is used to provide a reflective region by being reflective itself. For some such applications, the reflection-facilitation element is inflatable with a gas that has an acoustic impedance that is different to that of the target tissue, and thereby reflects at least some of the ultrasound energy that passes through the target tissue, back through the target tissue. Inflatable reflection-facilitation elements may further protect proximate tissues on the second side of the target tissue by increasing a distance between the target tissue and the proximate tissues.
For some applications, the reflective region and/or the reflection-facilitation element facilitates the use of higher energy (e.g., higher intensity and/or density) ultrasound, due to the protective effect. For some applications, the reflective region and/or the reflection-facilitation element facilitates the use of lower energy (e.g., lower intensity and/or density) ultrasound, due to the enhanced ablation effect. For some applications, a focal point of the ultrasound transducer is located in the target tissue, and the ultrasound energy applied is generally capable of ablating the cardiac tissue. For other applications, the ultrasound transducer transmits non-focused ultrasound waves. Additionally or alternatively, the ultrasound transducer transmits low intensity focused or non-focused ultrasound waves.
Thereby, providing a reflective region (e.g., by using a reflection-facilitation element) on the other side of the target tissue to an ultrasound transducer, typically increases the efficacy and/or safety of ultrasound-based ablation.
Reference is made to
Introducer 24 is configured to deliver the inflation fluid (1) to the interior of inflatable element 22 (i.e., so as to inflate the inflatable element), and (2) to a site exterior to the inflatable element (e.g., immediately outside of the inflatable element). That is, element 24 is configured to deliver a first portion of the inflation fluid to the interior of inflatable element 22, and a second portion of the inflation fluid to the exterior of the inflatable element. For some applications, the first and second portions of the inflation fluid provide distinct reflective regions (e.g., first and second reflective regions, such as reflective regions with a non-reflective region inbetween). For some applications, the first and second portions of the inflation fluid provide a generally continuous reflective region (e.g., the second portion being disposed outside the inflatable element, immediately opposite the first portion).
For some applications, introducer 24 is configured such that the inflation fluid is independently deliverable to the interior and exterior of inflatable element 22 (e.g., such that a user may select respective amounts (e.g., volumes or pressures) of the inflation fluid to be delivered to the interior and exterior of the inflatable element). For some applications, the introducer is configured such that the amount of inflation fluid delivered to the interior of the inflatable element varies with (e.g., is proportionally related to) the amount of inflation fluid delivered to the exterior of the inflatable element.
Reflection-facilitation element 20 (e.g., the inflatable element thereof and/or the introducer thereof) defines (1) an inlet, via which the inflatable element is inflated, and (2) an outlet, via which the inflation fluid is delivered to the exterior of the inflation element (e.g., as described hereinbelow for reflection-facilitation elements 30, 40 and 50).
Typically, inflatable element 22 is configured to be placed in the pericardial cavity of the subject, such that the inflation fluid delivered to the interior and/or exterior of the inflatable element is thereby disposed in the pericardial cavity. That is, (1) the portion of the inflation fluid that is delivered to the interior of the inflatable element is disposed within the inflatable element, within the pericardial cavity, and (2) the portion of the inflation fluid delivered to the exterior of the inflatable element (e.g., via an outlet as described hereinbelow with reference to
For some applications of the invention, inflatable element 22 comprises an anti-inflammatory substance. For example, inflatable element 22 may be coated in an immobilized and/or biosorbent anti-inflammatory drug.
In
Tubular element 36 is in fluid communication with inflatable element 32. For example, an end (e.g., a distal end) of element 36 may open into a proximal side of element 32, the opening into element 32 defining a port (e.g., an inlet 37). Tubular element 38 is typically not in fluid communication with element 32, but extends through element 32 so as to be in fluid communication with a site external to element 32 that is on a distal side of element 32. The distal end of tubular element 38 thereby defines a port (e.g., an outlet 39). Thereby, introducer 34 is configured to deliver inflation fluid (1) to the interior of inflatable element 32 via tubular element 36, and (2) to a site exterior to the inflatable element via tubular element 38.
Tubular element 46 is in fluid communication with inflatable element 42. For example, an end (e.g., a distal end) of element 46 may open into a proximal side of element 42, the opening into element 42 defining a port (e.g., an inlet 47). Outlet 49 is typically not directly coupled to element 42, but is disposed at a distal side of element 42 so as to provide fluid communication between the interior of element 42 and a site external to element 42 that is on a distal side of element 42. Thereby, outlet 49 typically provides fluid communication between tubular element 46 and the site external to element 42 that is on a distal side of element 42. Thereby, introducer 96 is configured to deliver inflation fluid (1) to the interior of inflatable element 42 via tubular element 46, and (2) to a site exterior to the inflatable element via outlet 49. Alternatively, outlet 49 is disposed at a different site on the inflatable element, e.g., near inlet 47, between inlet 47 and outlet 49.
Typically, outlet 49 comprises a fluid-control device, such as a valve 51. For some applications, the valve is configured to allow the inflation fluid to flow from inflatable element 42 to the site exterior to the inflatable element (i.e., through outlet 49) only when a pressure at the site exterior to the inflatable element is lower than a threshold value. For some applications, the valve is configured to allow the inflation fluid to flow through outlet 49 only when a pressure within inflatable element 42 is greater than a threshold value. For some applications, the threshold values are absolute values (e.g., pressures). For some applications, the threshold values are relative values (e.g., relative to each other). For example, the valve may be in an open state if the difference in pressure between the inside of inflatable element 42 and the site exterior to the inflatable element is greater than a threshold value.
Tubular element 56 is in fluid communication with inflatable element 52. For example, an end (e.g., a distal end) of element 56 may open into a proximal side of element 52, the opening into element 52 defining a port (e.g., an inlet 57). Tubular element 58 is typically not in fluid communication with element 52, but is in fluid communication with a site external to element 52 that is on a proximal side of element 52. For example, and as shown in
It is noted that the position of the inlets and outlets described with reference to
For some applications of the invention, reflection-facilitation element 20 (e.g., inflatable element 22 and/or introducer 24) defines one or more lumens configured to be slidable over a guidewire, for facilitating delivery of the inflatable element to the desired location.
Reference is made to
As shown in
Ultrasound tool 90 is introduced into a chamber 110 of the heart (e.g., a left atrium of the heart)(
Inflation fluid 122 has an acoustic impedance that is different to that of the surrounding tissue. Typically, the inflation fluid comprises a gas of lower density than the surrounding tissue. Delivery of inflation fluid 122 to the interior and exterior of inflatable element 22 (i.e., inflating inflatable element 22 and delivering inflation fluid free into the pericardial cavity) thereby provides at least one reflective region on the other side of cardiac tissue 112 from tool 90). For example, portion 123 may provide one reflective region and portion 124 may provide another reflective region, or portions 123 and 124 may provide one continuous reflective region.
Ultrasound energy is applied to tissue 112 using tool 90 (e.g., transducer 92 thereof), directly heating the tissue in the acoustic focal volume (
For some applications of the invention, transducer 92 is configured to generate ultrasound energy at more than one frequency and/or with more than one focal point. For example, transducer 92 may generate (1) first ultrasound energy, e.g., at a frequency of greater than 7 MHz and/or less than 11 MHz (e.g., 9 MHz), and that has a focal point within the tissue of the target site, and (2) second ultrasound energy at a frequency lower than the frequency of the first ultrasound energy (e.g., of greater than 2 MHz and/or less than 6 MHz (e.g., 4 MHz)), that has a focal point on the other side of the tissue of the target site. The second ultrasound energy is thereby typically reflected by the reflective region (e.g., by inflation fluid 122), such that it too focuses on the tissue of the target site.
For applications in which tool 90 comprises a rotatable ultrasound tool, the tool is rotated (e.g., as indicated by arrow 14A and/or in the opposite direction), such that ultrasound transducer 92 can be aimed at any desired location around an orifice of blood vessel 104. Rotation of tool 90 allows circumferential ablation surrounding the orifice of blood vessel 104, e.g., a pulmonary vein ostium, such that blood vessel 104 is electrically isolated from other areas of the heart, thereby blocking conduction of undesired electrical signals from blood vessel 104 into the heart, such as for treatment of atrial fibrillation. Thus, tool 90 or an element thereof is typically rotated a full 360 degrees around a longitudinal axis of tool 90.
Alternatively, and as described above, for some applications, tool 90 is configured to apply ultrasound energy in 360 degrees, such as in an annular focal pattern (e.g., as described with reference to
Reference is again made to
Reference is again made to
Reference is again made to
For example, the speed of sound in the target site generally varies with the temperature of the target tissue. Typically, the speed of sound in cardiac muscle increases as the temperature of the cardiac muscle increases. A first pulse of ultrasound energy is transmitted by transducer 92, reflected, and detected by the ultrasound detector, and the TOF is determined. The TOF of the first pulse is dependent on the temperature of the target site (i.e., the tissue thereof) and the distance to the reflective region. The TOF of a second pulse of ultrasound energy is determined, and the difference between the TOF of the first and second pulses is used to determine a the temperature of the target site and/or a temperature change of the target site. Typically, the distance between tool 90 (i.e., the transducer and the ultrasound detector) and the reflective region is maintained between the two pulses.
Typically, the first pulse is transmitted before an ablative pulse of ultrasound energy is transmitted, and the second pulse is transmitted after the ablative pulse of ultrasound energy is transmitted.
Reference is made to
For some applications of the invention, one or more ablation sites 154 (e.g., ablation sites 154a and 154b) are generated that circumscribe the tissue adjacent to and/or within respective common ostia 163a and 163b, such as shown in
It is typically desirable to provide the reflective region adjacent to as much as possible of the tissue to be ablated (e.g., to provide the reflective region adjacent to most of the tissue, for example all of the tissue to be ablated). For applications of the invention in which the ablation site(s) are at or near the left atrium, it is thereby desirable to provide the reflective region at least in a posterior region of the pericardial cavity (i.e., posterior to the heart, adjacent to the left atrium). During a typical cardiac tissue ablation procedure, the subject is in a supine position, and the weight of the heart rests on the posterior portion of the pericardium, thereby typically displacing (e.g., squeezing out) at least part of the pericardial fluid disposed in this portion of the pericardium, e.g., into an anterior portion of the pericardium. Similarly, for some applications in which only free fluid (e.g., gas) is introduced to the pericardial cavity so as to provide the reflective region, the introduced fluid is displaced.
Typically, inflatable element 22 (e.g., a part thereof) is placed within the pericardial cavity at placement site 150, which is posterior to the heart, and thereby below the heart when the subject is in the supine position. It is hypothesized that the placement of inflatable element 22 at placement site 150, reduces the displacement of inflation fluid 122 (i.e., portion 124 thereof) from the posterior region of the pericardium, that would otherwise occur if portion 124 were delivered in the absence of inflatable element 22.
It is further hypothesized that the placement of inflatable element 22 at placement site 150 increases a distance between the ablation site and other tissue. For example, the esophagus is generally immediately posterior to the heart, and esophageal injury is an established risk in ablation treatments for atrial fibrillation. For some applications, when placed at placement site 150, inflatable element 22 increases a distance between left atrium 160 (and thereby the ablation site) and the esophagus, thereby reducing the risk of esophageal injury.
At sites at which inflatable element 22 contacts the tissue (e.g., the visceral pericardium) close to the ablation site (e.g., when the inflatable element is opposite transducer 92), the inflatable element 22 (and/or portion 123 of inflation fluid 122 therein) typically provides (e.g., acts as) the reflective region. At sites at which portion 124 of inflation fluid 122 contacts the tissue (e.g., the visceral pericardium) close to the ablation site (e.g., when the free inflation fluid is opposite transducer 92), portion 124 of the inflation fluid typically provides (e.g., acts as) the reflective region.
Reference is made to
Element 20 is typically delivered in a deflated state thereof. Further typically, element 20 is delivered intracatheterally. For some applications, element 20 is coupled to a semi-rigid spine that facilitates steering of element 20. For some applications in which element 20 is coupled to a semi-rigid spine, element 20 is delivered without a catheter (e.g., element 20 is delivered exposed). For some applications, element 20 comprises a miniature forceps (e.g., coupled to a distal part of inflatable element 22 or a delivery catheter), which facilitate separation (e.g., blunt dissection) of tissues, and thereby delivery of element 20. For some applications, inflatable element 22 is inflated during delivery so as to facilitate separation of tissues (e.g., blunt dissection), and thereby delivery of element 20. For some applications, this inflation of element 22 comprises inflation of a compartment (e.g., a sub-compartment) of element 22, e.g., with a liquid.
Typically, element 20, element 22, element 24, and or the delivery catheter thereof, comprise one or more radiopaque markers, to facilitate location of the apparatus during delivery. The radiopaque markers may also be used to indicate a degree of inflation of inflatable element 22, and to facilitate location of the apparatus during removal from the body of the subject.
Following delivery and inflation of inflatable element 22, portion 124 of inflation fluid 122 is delivered to the pericardial cavity (i.e., free), so as to provide at least part of the reflective region. Portion 124 is not shown in
For some applications, an embodiment of reflection-facilitation element 20 is selected according to the position of the outlet thereof, thereby at least in part directing the delivery of portion 124. Typically, the anatomy of the pericardium at least in part restricts movement of portion 124 of the inflation fluid. For example, anatomical structures, such as pericardial reflections typically trap the inflation fluid. For some applications, structures (e.g., flaps and/or pockets) on the exterior of inflatable element 22 facilitate the trapping of the inflation fluid.
Reference is made to
Reference is made to
Additional inflatable element 300 is delivered to right atrium 164 of the subject. Typically, additional inflatable element 300 is delivered transluminally, such as by advancing the inflatable element through inferior vena cava (IVC) 166 or superior vena cava (SVC) 168. However, the scope of the invention includes delivering element 300 to the right atrium using any suitable means. Additional inflatable element 300 is inflated (e.g., with inflation fluid 122) via an introducer 302.
As described hereinabove, reflection-facilitation element 20 provides at least one reflective region on the other side of the target tissue from tool 90. At least one region of ablation site 154b includes part of the interatrial septum (not shown). Thereby, for at least one region of ablation site 154b, the other side of the target tissue is within the right atrium. Additional inflatable element 300 provides a reflective region at the right-atrial surface of the interatrial septum, thereby facilitating ablation of the region of ablation site 154b that includes part of the interatrial septum, thereby facilitating the generation of a 360-degree ablation site, and thereby facilitating the electrical isolation of at least one pulmonary vein from the left atrium.
Although
Reference is made to
Ultrasound transducer 400 is advanced into left atrium 160 of the subject, and is positioned in a vicinity of a pulmonary vein 162, such as a first pulmonary vein 406. Typically, a tool 402, comprising transducer 400 and a guiding element 404 is advanced into atrium 160, and the transducer is positioned by placing the guiding element within the pulmonary vein. The guiding element thereby stabilizes transducer 400 in the vicinity of the pulmonary vein (e.g., the ostium thereof). For some applications, guiding element 404 comprises a guidewire 405. For some applications, guiding element 404 comprises an anchoring element, and is anchored (e.g., coupled) to the pulmonary vein. For some such applications, guiding element 404 comprises anchoring element 98 and/or inflatable element 100, and is anchored to the pulmonary vein by inflating the inflatable element (e.g., as described hereinabove with reference to
While ultrasound transducer 400 is in the vicinity of first pulmonary vein 406, the transducer is driven to apply ultrasound energy having a non-circular 360-degree focal pattern 420. For example, the focal pattern and lesion may be generally oval (e.g., elliptical). The non-circular focal pattern of the ultrasound energy facilitates the generation of an annular lesion while the transducer is disposed at a site that is not at the center of the lesion (e.g., a site that is not equidistant from all parts of the lesion). Transducer 400 is configured and/or oriented such that the non-circular 360-degree focal pattern generates an annular lesion that circumscribes more than one pulmonary vein ostium. Typically, the lesion circumscribes the ostium of first pulmonary vein 406 and the ostium of an ipsilateral second pulmonary vein 408. For example, the lesion may be similar to ablation sites 154a and 154b, described with reference to
Typically, transducer 400 generates the ultrasound energy from a lateral surface thereof. For some applications of the invention, transducer 400 comprises a rotationally asymmetric ultrasound transducer 410, as shown in
For some such applications, transducer 410 comprises a piezoelectric transducer (e.g., one or more piezoelectric transducers). For some such applications, transducer 410 comprises a Capacitive Micromachined Ultrasonic Transducer (CMUT) (e.g., an array of CMUTs).
For some applications, transducer 400 and/or transducer 410 comprises a phased array of transducers (e.g., CMUTs), configured to apply the ultrasound energy in the non-circular 360-degree focal pattern. For some such applications, transducer 400 is not necessarily rotationally asymmetric. For example, transducer 400 may comprise a generally cylindrical array of CMUT (e.g., as shown in
For some applications, transducer 400 comprises a unidirectional transducer with variable focal length, and the annular lesion is generated by rotating the transducer around a longitudinal axis of tool 402 (e.g., by rotating tool 402), and varying the focal length of the transducer as appropriate.
Reference is made to
For some applications, transducers 442 and 444 are configured to apply ultrasound energy simultaneously, e.g., such that transducer unit 440 acts as a single transducer that applies ultrasound energy radially in 360 degrees. For some applications, transducer unit 440 is configured to apply ultrasound energy using transducers 442 and 444 independently of each other, e.g., each applying ultrasound energy radially in 180 degrees. For some applications, transducers 442 and 444 have different focal lengths from each other, and are used to facilitate the generation of an asymmetrical lesion, such as, or similar to, the non-circular 360-degree lesion described with reference to
For some applications, transducer unit 440 is used to generate a 360-degree lesion using both transducers and also (e.g., beforehand and/or subsequently) to generate a 180-degree lesion using one transducer. For some applications, such techniques are used to generate a “Cox Maze”, as is known in the art, for treating atrial fibrillation.
It is to be noted that transducers 442 and 444 are shown as identical, purely for illustration, and that the scope of the invention includes other configurations (e.g., shapes) of the transducers and/or transducer unit 440. For example, one transducer may have a longer focal distance than the other, so as to generate a non-circular 360-degree lesion (e.g., as described hereinabove with reference to
Reference is made to
Typically, and as shown in
For some applications, camera unit 470 is configured to control, or to facilitate control of, transducer 462 (e.g., to act as a control unit of unit 460). For example, in response to detecting a degree of ablation (e.g., a desired degree of ablation) of target site 472, camera unit 470 may be configured to reduce the amplitude of ultrasound energy applied by transducer 462 (e.g., to stop the transducer from applying ultrasound energy).
For some applications, camera unit 470 comprises (e.g., camera units 470a and 470b comprise) a movable mount 466 on which camera 464 is mounted, such that the camera is movable, e.g., so as to facilitate acquisition of images of more than one portion of the target site. For example, and as shown in
For some applications, and as shown in
It is to be noted that camera unit 470 is shown as a component of transducer unit 460 purely for example, and that the camera unit may be used in combination with other transducers and/or transducer units described herein.
Reference is made to
System 480 is delivered (e.g., percutaneously) into left atrium 160 of the subject, and inflatable element 184 is inflated with liquid 486, such that the inflatable element contacts wall 161 of the atrium (
For some applications, transducer 482 is configured to have a circular focal pattern, and thereby to generate a circular ablation pattern. For some such applications, inflatable element 484 has a generally circular cross-section, and is configured, when inflated, to press against wall 161 of the atrium, and to temporarily (e.g., reversibly) reshape the wall to have a generally circular cross-section (e.g., a more circular cross-section), so as to “match” the focal pattern of the transducer (i.e., so as to become more similar in size and/or shape to the focal pattern)(
System 480 comprises at least one inflation tube 490, in fluid communication with inflatable element 484, for inflating the inflatable element. For some applications, inflatable element comprises two or more inflation tubes 490 (e.g., inflation tubes 490a and 490b), so as to facilitate circulation of liquid 486, e.g., to cool transducer 482 and/or wall 161. For example, one inflation tube (e.g., inflation tube 490a) may be used to introduce relatively cool liquid 486 into inflatable element 484, and the other inflation tube (e.g., inflation tube 490b) may be used to remove relatively warm liquid 486 from the inflatable element. For such applications, liquid 486 is typically acoustically and/or optically transparent.
For some applications of the invention, system 480 further comprises a camera, coupled to transducer 482, and configured (e.g., positioned) to acquire images of the target site at which a lesion will be, is being, and/or has been generated by the transducer (e.g., as described for camera 464 with reference to
System 480 may be used in combination with one or more of the reflection-facilitation elements described herein, so as to increase efficacy and/or safety of the ultrasound-based ablation.
Reference is made to
Reference is made to
Reflection-facilitation element 502 is configured to be placed within a pulmonary vein 162 of the subject, in a vicinity of an ostia thereof, and to be inflated with an inflation fluid (e.g., a gas), as shown in
Typically, inflation of element 502 secures system 500 in place by anchoring to the pulmonary vein. Thereby, element 502, when inflated on the first side of the ostium, is dimensioned to facilitates positioning of transducer 504 at the second side of the ostium. For some applications, element 502 is shaped to define a lumen therethrough, such that blood may continue to flow into the pulmonary vein during the time that element 502 is inflated.
When reflection-facilitation element 502 is disposed within pulmonary vein 162, and transducer 504 is disposed in atrium 160 in a vicinity of the pulmonary vein, cardiac tissue 506 (e.g., part of atrial wall 161) that circumscribes the ostium of the pulmonary vein is disposed between the transducer and the reflection-facilitation element. Transducer 504 applies ultrasound energy toward cardiac tissue 506 and element 502. At least part of the ultrasound energy 510 reaches element 502. Due to the difference in acoustic impedance between the gas and cardiac tissue 506, the gas acts as a reflective region, and ultrasound waves that reach the gas are reflected. Thus, at least part of the ultrasound energy that passes through cardiac tissue 506 is typically by element 502, back through the cardiac tissue, resulting in temperature elevation and enhanced ablation of the cardiac tissue, e.g., as described hereinabove, mutatis mutandis. For some applications, and as shown in
Reference is made to
Reflection-facilitation element 522 is configured to be placed within atrium 160 of the subject, in a vicinity of the ostium of a pulmonary vein 162, as shown in
Reflection-facilitation element 542 may comprise any material that reflects ultrasound. For some applications, element 542 comprises an inflatable reflection-facilitation element. For some applications, reflection-facilitation element 524 comprises a metal, such as gold or stainless steel, to facilitate reflection of ultrasound energy. Furthermore, the metallic composition may facilitate positioning of element 524 at the ostium, using imaging techniques such as fluoroscopy. For some applications, element 524 comprises expanded polystyrene.
For some applications, system 520 is positioned by placing reflection-facilitation element 524 against atrial wall 161. That is, for some applications, element 524 is dimensioned and/or shaped such that placing the element against wall 161 such that the element circumscribes the ostium of pulmonary vein 162, facilitates placement of transducer 522 at a correct position (e.g., depth) within the pulmonary vein.
When reflection-facilitation element 522 is disposed in atrium 160 in a vicinity of the pulmonary vein, and transducer 524 is disposed within pulmonary vein 162, cardiac tissue 506 (e.g., part of atrial wall 161) that circumscribes the ostium of the pulmonary vein is disposed between the transducer and the reflection-facilitation element. Transducer 524 applies ultrasound energy 520 toward cardiac tissue 506 and element 522. At least part of the ultrasound energy 520 reaches element 522, and at least part of that energy is reflected by element 522, back through the cardiac tissue, resulting in temperature elevation and enhanced ablation of the cardiac tissue, e.g., as described hereinabove, mutatis mutandis. For some applications, and as shown in
Reference is made to
Each system is configured to ablate cardiac tissue in the immediate vicinity of the elongate member, thereby creating a circumferential lesion that generally circumscribes the four pulmonary vein ostia. That is, the shape of the lesion is generally similar to the shape of the elongate member in the looped state. The shape of the lesion is typically similar to a “box lesion”, as is known in the atrial fibrillation art, and is configured to electrically isolate all four pulmonary vein ostia from the left atrium (or a large portion thereof), so as to treat atrial fibrillation.
For each system, the ultrasound transducer is placed on one side of the tissue to be ablated, and the reflection-facilitation element is placed, and provides a reflective region, on the other side of the tissue. The reflective region increases the efficacy and/or safety of the ultrasound-based ablation, as described hereinabove.
For clarity,
Elongate member 542 is placed pericardially such that the elongate member forms a loop that generally encompasses the ostia of all four pulmonary veins 162, as described hereinabove, and as shown in
Elongate member 542 (e.g., transducers 546 thereof) are driven to apply ultrasound energy, at least some of which passes through the tissue of the atrial wall, and is reflected by element 544, thereby ablating tissue disposed between member 542 and element 544, e.g., as described with reference to
For some applications, the apparatus and techniques described with reference to
Elongate member 562 is placed pericardially such that the elongate member forms a loop that generally encompasses the ostia of all four pulmonary veins 162, as described hereinabove, and as shown in
Ultrasound transducer unit 564 is driven to apply ultrasound energy, at least some of which passes through the tissue of the atrial wall, and is reflected by element 562, thereby ablating tissue disposed between unit 564 and element 562, e.g., as described with reference to
Elongate member 582 is placed pericardially such that the elongate member forms a loop that generally encompasses the ostia of all four pulmonary veins 162, as described hereinabove, and as shown in
The magnetic coupling draws transducer 586 and element 584 toward each other on either side of the wall of left atrium 160 (
It is to be noted that the scope of the invention includes the transducer and the reflection-facilitation element in reverse positions. That is, for some applications of the invention, elongate member 582 comprises the reflection-facilitation element, and the transducer is configured to be disposed in atrium 160.
It is hypothesized that, because ablation is dependent on reflection-facilitated concentration of ultrasound energy, for some applications, ultrasound transducer 586 may be configured to apply ultrasound energy at an amplitude that is insufficient to ablate tissue in the absence of such reflection, and thereby advantageously insufficient to inadvertently ablate non-target tissues. Further, due to this configuration, for some applications, transducer 586 is configured to apply ultrasound energy in 360 degrees laterally from the longitudinal axis of longitudinal member 582, such that positioning of the elongate member within the pericardium is generally independent of the rotational orientation of the elongate member around the longitudinal axis thereof.
Reference is made to
Typically, at least one of the magnetically-attractable elements comprises a magnet (e.g., an electromagnet). For some applications, both magnetically-attractable elements comprise magnets (e.g., electromagnets). For some applications, one of the magnetically-attractable elements comprises a metallic element that is not itself magnetic, but is magnetically-attractable by the other magnetically-attractable element. Because transducer 612 is typically wiredly coupled to the outside of the subject, for some applications, it is advantageous that transducer unit 604 comprise the electromagnet,
For some applications, the techniques described with reference to
Reference is made to
Elements 620 and 630 are typically configured, when inflated, provide respective reflective regions for ultrasound energy, and to thereby increases efficacy and/or safety of the ultrasound-based ablation, as described hereinabove. Elements 620 and 630 may be used in combination with other reflection-facilitation elements described herein.
Reference is now made to
Placement site 642 (marked with an X) is within oblique sinus 646 of the pericardial cavity, between pulmonary veins 162 (e.g., ostia thereof), and inferior to sinus reflections 170. Placement site 644 (marked with an X) is within transverse sinus 648 of the pericardial cavity, superior to sinus reflections 170. It is hypothesized that placement of one or more inflatable reflection-facilitation elements at the placement sites at least in part provides the reflective region and distancing described in the previous paragraph.
Reference is made to
Element 660 (
Inflatable portion 671 (
Typically, inflatable reflection-facilitation elements 660 and 670 (e.g., inflatable portions thereof) are each configured to be disposed at placement site 642 (
For some applications, elements 660 and 670 comprise an ablation element (e.g., an ultrasound, RF or cryogenic element; not shown), disposed on one side of the inflatable portion. For such applications, the reflection-facilitation elements are configured to be used as integrally-insulated ablation tools in which the gas used to inflate the inflatable portion insulates and/or distances tissues on one side of the inflatable portion from the ablation element on the other side of the inflatable portion.
Reference is made to
For some applications, element 680 is configured to be delivered within a steerable catheter (not shown), and each inflatable member is deployed from the catheter at its respective placement site. For such applications, longitudinal element 686 typically comprises at least part of an inflation tube. Alternatively or additionally, longitudinal element 686 may itself be steerable.
Reference is made to
For some applications, elements 700 and 710 are further configured to facilitate navigation thereof toward the placement sites thereof. For example, the electrodes of the elements are typically radiopaque, and may facilitate navigation using imaging techniques such as fluoroscopy. Alternatively or additionally, the electrodes may be electrically coupled to an extracorporeal monitor, and facilitate navigation by detecting electrical signals of the heart (e.g., ECG signals). It is to be noted that such navigation techniques may be combined with any of the other reflection-facilitation elements described herein. For example, other reflection-facilitation elements may comprise electrodes that facilitate navigation by detecting electrical signals of the heart.
Reference is made to
Magnetic guiding member 744 is percutaneously (e.g., transluminally) delivered to SVC 168, and electromagnet 745 is energized, thereby magnetically coupling member 744 to element 742. The magnetic field of electromagnet 745 draws element 742 into (e.g., deeper into) the transverse sinus (
Magnetic guiding member 764 is percutaneously (e.g., transluminally, such as transfemorally) delivered to a portion of aorta 761 of the subject that is in the vicinity of element 762. Electromagnet 765 is energized, thereby magnetically coupling member 764 to element 762. Member 764 is subsequently moved upstream through aorta 761. The magnetic field of electromagnet 765 draws element 762 along with member 764 (but in the pericardium; outside of the aorta), and into transverse sinus 648 (
Magnetic guiding member 784 is delivered to a portion of esophagus 781 of the subject that is in the vicinity of element 782. (For clarity, esophagus 781 is not shown in
Reference is made to
Reflection-facilitation element 800 comprises a longitudinal inflatable member 802, which is introduced to the pericardium and is positioned so as to circumscribe heart 10, generally around a superior-inferior axis of the heart. For some applications, and as shown in
Reference is made to
Element 820 has an outer surface that is configured to grip and/or adhere to tissues. For example, the outer surface may comprise a hydrophobic material, such as polycaprolactone (PCL), polyethylene oxide (PEO), and/or TPRE. Element 820 has a deflated state in which the element is generally concave, such that a distal end 821 of element 820 is disposed within the concavity (
For some medical procedures, separation of adjacent tissues without cutting (known as “blunt dissection”) is a useful technique for gaining access to the target site. For some applications, element 820 may be used as a blunt dissection tool, mutatis mutandis, in addition to, or instead of, as a reflection-facilitation element.
Reference is made to
System 840 further comprises a control unit 846, configured to drive the transducers to apply ultrasound. Typically, and as shown in
Transducer unit 842 is introduced to the vicinity of the tissue to be ablated. For example, unit 842 may be configured to be placed within a chamber of the heart of the subject, so as to ablate tissue of the wall of the chamber. For example, as shown in
Control unit 846 drives transducer unit 842 (e.g., transducers 844 thereof) to apply a first application 850 of ultrasound energy to the tissue (
Control unit 846 receives the signal generated by unit 842. Typically, control unit 806 determines the location of anatomical features (e.g., atrial wall 161 and pulmonary vein ostia 843) in response to receiving the signal. For example, control unit 846 may comprise a mapping unit 848, which generates a map of the anatomy. For some applications, the map is entirely internal and is used solely by system 840. For some applications, the map is displayed on an extracorporeal display 860, e.g., such that a physician may view the map during and/or after the procedure.
In response to the signal, control unit 846 drives transducer unit 842 (e.g., transducers 844 thereof) to apply a second application 854 (e.g., portions 854a and 854b thereof) of ultrasound energy, configured to ablate the tissue (
Thereby, system 840 is configured to perform acoustic location (e.g., mapping) of anatomical features relative to transducer unit 842, and to subsequently direct and/or configure ultrasound to ablate tissue in the desired location and/or manner.
As described hereinabove, a reflective region may be provided by providing a reflection-facilitation element on the other side of the target tissue to an ultrasound transducer, thereby typically increasing efficacy and/or safety of ultrasound-based ablation.
For applications in which a reflection-facilitation element is used, control unit 846 typically configures the second application of ultrasound energy in response to locating element 856. At portions of the target site that are determined to be backed by a reflective region (e.g., a reflection-facilitation element), the second application of ultrasound energy (e.g., at least a portion 854b thereof) is configured to utilize the reflective region, e.g., so as to increase safety and/or efficiency of the ultrasound-based ablation.
Reference is made to
Sensor 884 may comprise an electrical sensor, an ultrasound sensor, and/or an imaging device, and is configured to sense the location of at least the sensor (e.g., a location of tool 800) with respect to the tissue being penetrated. For example, sensor 884 may be configured to sense a distance to and/or a depth within a tissue (e.g., the fibrous pericardium), by detecting changes in color and/or brightness of light, electrical impedance, and/or reflection of ultrasound energy. For some applications, sensor 884 comprises an ultrasound transducer, configured to apply the ultrasound energy that is detected (i.e., sensor 884 is an ultrasound transceiver).
Tool 880 is advanced to the pericardium of the subject, and at least needle 882 is rotated, such that the needle penetrates the fibrous pericardium, in a manner similar to that of a corkscrew. When sensor 884 determines that a desired depth of penetration has been achieved, the rotation is stopped. For example, a control unit 890 may receive, from sensor 884, a signal indicative of the depth of penetration, and display information indicative of the depth of penetration (e.g., indicative of penetration of the parietal pericardium), such that a physician may control rotation and/or advancement of needle 882. For some applications, the control unit controls rotation and/or advancement of needle 882, and automatically stops the rotation when the desired depth of penetration has been achieved.
For some applications, needle 882 is shaped to define a lumen therethrough. A guidewire 892 is disposed within, and/or is slidable through, the lumen. While distal end 886 of the needle is disposed within the pericardial cavity, the guidewire is advanced distally from the distal end of the needle, and into the pericardial cavity. Needle 882 is subsequently removed from the pericardium, leaving behind guidewire 892, to be used for facilitating further pericardial access.
It is to be noted that tool 880 may be used to facilitate access other cavities of the body of the subject, other than the pericardial cavity.
Reference is made to
Element 910 further comprises one or more adjustable restricting elements 918, configured to limit expansion of portion 912 in a given dimension when inflated, such that the expansion in the given dimension is controllable from outside the body of the subject.
For some applications, element 910 comprises a plurality of adjustable restricting elements 918, each element 918 being configured to control a maximum length of the inflatable portion in a respective dimension. Thereby, the shape of inflatable portion 912 is adjustable in more than one dimension. For example, a maximum length in one dimension may be reduced, and a maximum length in another dimension may be increased. Thereby, for some such applications, inflatable portion 912 is configured such that the shape thereof is controllable while the inflatable portion is disposed within the body of the subject.
Typically, inflatable reflection-facilitation element 910 (e.g., inflatable portion 912 thereof) is configured to be disposed at placement site 642 within the pericardial cavity (
Reference is made to
As described hereinabove, during a typical cardiac tissue ablation procedure, the subject is in a supine position, and the weight of heart 10 rests on the posterior portion of the pericardium. For some applications, it is desirable to introduce free gas (e.g., gas that is not within an inflatable element) into the pericardium (e.g., instead of, or in addition to, an inflatable reflection-facilitation element), such as described with reference to
Reflection-facilitation element 952 thereby typically comprises an introducer 953 (e.g., a needle or a tube), and provides a reflective region by facilitating delivery of free gas into the pericardial cavity. Transducer unit 950 is delivered (e.g., transluminally) to the ventricle (e.g., left ventricle 944), and reflection-facilitated ultrasound ablation is performed on ventricular wall 942, e.g., at an ablation site 943. Alternatively, reflection-facilitation element 952 may comprise an inflatable reflection-facilitation element, such as those described herein.
Typically, system 940 further comprises a second reflection-facilitation element 954, configured to be provide a reflective region in a second ventricle of the heart. For example, and as shown in
For some applications, reflection-facilitation element 954 is used without providing a reflective region in the pericardial cavity (e.g., without using reflection-facilitation element 952). For example, for applications in which it is desirable to ablate tissue only at ablation site 947 in interventricular septum 946, element 954 is placed in right ventricle 948 and a transducer unit (e.g., unit 950) is placed in left ventricle 944, but gas is not delivered to the pericardial cavity.
For some applications of the invention, the gas used to provide the reflective regions (e.g., the gas delivered to the pericardium and/or the gas used to inflate the inflatable reflection-facilitation elements) is cooled at the start of the procedure and/or throughout the procedure, so as to reduce heating of heart tissue. For example, the free gas delivered to the pericardium may be cooled, so as to cool the coronary arteries during ablation of nearby (e.g., underlying) tissue. Similarly, cooling of inflation fluid (e.g., gas and/or liquid) may be combined with other techniques described herein.
Reference is again made to
For some applications of the invention, the temperature of the fluid (e.g., gas) used to inflate one or more reflection-facilitation elements and/or the pericardial cavity (e.g., so as to provide a reflective region) is regulated (e.g., adjusted and/or maintained). For example, the temperature may be adjusted prior to inflation, and/or may be maintained after inflation (e.g., by circulating the intracorporeal portion of the fluid with an external supply). For some such applications, the fluid is cooled, so as to reduce undesirable heating of tissues (e.g., those outside of the target ablation site). For some such applications, the fluid is heated, so as to increase ablation at the target ablation site (e.g., by a thermal effect).
For some applications of the invention, the reflection-facilitation element comprises a temperature sensor, and is configured to sense the temperature of the tissue of the subject, such as the target tissue being treated. Typically, such temperature sensing facilitates ablation by ensuring sufficient heating and/or preventing overheating of the target tissue. For some applications of the invention, the reflection-facilitation element comprises, or is in fluid communication with, a pressure sensor, configured to prevent over-inflation of the reflection-facilitation element.
For some applications, apparatus described hereinabove comprise temperature-resistant materials, according to ablation techniques used. For example, reflection-facilitation elements (e.g., inflatable portions thereof) that are used to facilitate RF and/or ultrasound ablation may comprise thermoplastic polyurethane (TPU) and/or nylon 12, which are relatively heat-resistant. Conversely, reflection-facilitation elements (e.g., inflatable portions thereof) that are used to facilitate cryogenic ablation may comprise low density polyethylene (LDPE), which is relatively cold-resistant.
Reference is again made to
Reference is again made to
It will be appreciated by persons skilled in the art that the present invention is not limited to what has been particularly shown and described hereinabove. Rather, the scope of the present invention includes both combinations and subcombinations of the various features described hereinabove, as well as variations and modifications thereof that are not in the prior art, which would occur to persons skilled in the art upon reading the foregoing description.
The present application claims priority from U.S. Provisional Application 61/598,347 to Kardosh et al., entitled “Pericardium inflation device,” filed Feb. 14, 2012, U.S. Provisional Application 61/602,686 to Kardosh et al., entitled “Reflectance-facilitated ultrasound treatment and monitoring,” filed Feb. 24, 2012, and U.S. Provisional Application 61/698,773 to Kardosh et al., entitled “Reflectance-facilitated ultrasound treatment and monitoring,” filed Sep. 10, 2012, all of which are incorporated herein by reference. The present application is related to U.S. patent application Ser. No. 12/780,240 to Tsoref et al., filed on May 14, 2010 and published on Nov. 17, 2011 as US 2011-0282249, U.S. patent application Ser. No. 13/015,951 to Tsoref et al., filed on Jan. 28, 2011 and published as US 2011-0282203, and PCT application IL2011/000382 to Tsoref et al., filed on May 12, 2011 and published as WO 2011-141918, all of which are incorporated herein by reference.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IL13/50134 | 2/13/2013 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 61598347 | Feb 2012 | US | |
| 61602686 | Feb 2012 | US | |
| 61698773 | Sep 2012 | US |
