Patent Application
20250049609
This document relates to devices and related methods for delivering cooling therapy. For example, this document relates to implantable devices and related methods for the treatment of cardiac arrhythmias using temperature modulation.
Cardiac arrhythmias occur when there is a change in the rate and/or rhythm of the heartbeat due to changes in the normal sequence of cardiac electrical impulses. Abnormalities of cardiac rate and/or rhythm are associated with substantial morbidity and economic costs. Different types of cardiac arrhythmias include atrial, bradycardia, conduction disorders, premature contraction, tachycardia, and ventricular fibrillation.
Among these conditions, atrial fibrillation is the most common arrhythmia encountered in clinical practice, affecting over 2.5 million Americans. Recently, cardiac arrhythmias have been reported in hospitalized coronavirus disease 2019 (COVID-19) patients, with one study reporting arrhythmias in 44% of individuals with severe illness. Studies have indicated the incidence of atrial fibrillation in the United States will increase to an estimated 12.1 million people in 2030.
Multiple prospective randomized trials have demonstrated the clinical benefit of implantable cardiac defibrillators (ICDs) in saving the lives of at-risk individuals, leading to their wide-spread adoption. A downside associated with ICD therapy, however, is the pain associated with defibrillation, whether shocks are delivered appropriately or inappropriately.
In general, this disclosure describes implantable medical devices and related methods for use of the devices. Such implantable medical devices can be used to treat cardiac arrhythmias (e.g., atrial fibrillation) using temperature modulation as described herein. In some embodiments, the devices include a pair of electrodes that are used to measure the impedance of the epicardial tissue. Such impedance measurements can be used to indicate a level of contact and/or pressure between the enclosure of the heat exchange module and the epicardial tissue. Accordingly, the pair of electrodes can be used to ascertain situations in which there is sufficient contact and/or pressure (between the heat exchange module and the epicardial tissue) to be able to provide effective or optimal cooling therapy to the epicardial tissue.
In one aspect, this disclosure is directed to an implantable medical device including a cardiac lead sized for insertion in a cardiac cavity, the cardiac lead having a distal end, a proximal end, and a lead body extending therebetween, a heat exchange module disposed at the distal end of the lead body. The heat exchange module includes an enclosure having a first surface and a second surface, and one or more temperature sensors located within the enclosure.
In some embodiments, the heat exchange module of the implantable medical device further includes at least one pair of electrodes disposed on or coupled to the enclosure of the heat exchange module. In some embodiments, a first electrode of the pair of electrodes is disposed at a proximal portion of the enclosure and a second electrode of the pair of electrodes is disposed at a distal end portion of the enclosure. In some embodiments, the implantable medical device further includes one or more sensing electrodes disposed on the lead body. In some embodiments, the implantable medical device further includes a delivery tool including a sheath having a proximal end and a distal end, the sheath defining an interior region configured to receive the lead body, and a case having a distal end sized for enclosing the heat exchange module and an elongate body configured to receive the sheath.
In some embodiments, the sheath has a tubular body, and the interior region of the sheath is a lumen. In some embodiments, the elongate body of the case is tubular. In some embodiments, the sheath has an open, semi-cylindrical body that defines a channel configured to receive the lead body. In some embodiments, the elongate body of the case comprises a flat surface configured to receive the sheath and a retention clasp configured to removably secure the sheath. In some embodiments, the case comprises a handle at a proximal end of the elongate body. In some embodiments, the sheath and case are composed of a flexible or malleable material.
In some embodiments, the implantable medical device further includes a suture sleeve disposed between the distal end and the proximal end of the cardiac lead, the suture sleeve configured to secure the implantable medical device adjacent to a cardiac tissue. In some embodiments, the suture sleeve is removably coupled and/or slidably coupled to the lead body. In some embodiments, the implantable medical device further includes one or more connectors at the distal end of the cardiac lead, the one or more connectors configured to connect to a power supply.
In some embodiments, the one or more connectors comprise one or more lead terminal pins and one or more lead terminal rings. In some embodiments, the power supply is an implantable cardiac device. In some embodiments, the implantable cardiac device is an control module such as, but not limited to, an implantable cardioverter defibrillator (ICD), a pacemaker, or an external pulse generator. In some embodiments, the first surface of the heat exchange module is configured to be set to a first temperature that is less than a second temperature of the second surface of the heat exchange module. In some embodiments, the first temperature ranges from about 1 degree Celsius to about 37 degrees Celsius. In some embodiments, the second temperature ranges from about 37 degrees Celsius to about 50 degrees Celsius
In some embodiments, the heat exchange module comprises a heat pump (e.g., a Peltier device) located within the enclosure, and a heat sink located within the enclosure. The heat sink can comprise a phase change material and a thermally conductive interface structure positioned between the heat pump and the phase change material. In some embodiments, the heat exchange module comprises one or more fixation members configured to secure the heat exchange module adjacent to a cardiac tissue. In some embodiments, the one or more fixation members are loop-shaped wire members. In some embodiments, the one or more fixation filaments are biased in an outward direction. In some embodiments, the heat exchange module is configured to be an indifferent electrode.
In some embodiments, the cooling therapy systems described herein include at least one electrode and one ground electrode. The electrodes do not need to be of uniform size. In fact, depending on location of the electrodes, having different sizes/surface area may provide some advantages. It can vary depending on what measurements are being made using the electrodes. For embodiments in which the electrodes are on the enclosure of the cooling device, in some embodiments, the electrodes are equally sized. In contrast, if a remote anode/electrode approach is used, then it should be larger. In some embodiments, a remote anode/electrode can be three or four times the size of the electrode on the housing of the cooling device. In some embodiments, the best surface area would be about 5-20 mm2 for similarly sized electrodes, and 20 mm2 or larger for remote anode/electrode types. The materials of which the electrodes are comprised can include, but are not limited to, Platinum, platinum iridium, Elgiloy, Mp35N, titanium, and can be coated with platinum black, TiNi, Irox or sputtered other metallic bio-materials.
In another aspect, this disclosure is directed to a method of treating a cardiac arrhythmia in a patient in need thereof. The method can include making an incision into a pericardial tissue of the patient and inserting an implantable medical device through the incision. The implantable medical device can include a cardiac lead sized for insertion in a cardiac cavity, the cardiac lead having a distal end and a proximal end and a lead body extending therebetween. A heat exchange module can be disposed at the distal end of the lead body. The heat exchange module can include an enclosure having a first surface and a second surface, and one or more temperature sensors located within the enclosure. The method can also include securing the heat exchange module to a surface of a cardiac tissue using a delivery tool including a sheath having a proximal end and a distal end, the sheath defining an interior region configured to receive the lead body, and a case having a distal end sized for enclosing the heat exchange module and an elongate body configured to receive the sheath. The method can also include measuring tissue impedance to ascertain whether there is sufficient contact or pressure between the heat exchange module and the epicardial tissue as needed to deliver effective cooling therapy. The method can also include cooling the first surface of the implantable medical device to a therapeutic temperature for a therapeutic period of time.
In some embodiments, the therapeutic temperature ranges from about 5 degree Celsius to about 15 degrees Celsius. In some embodiments, the therapeutic period of time ranges from about 5 seconds to about 60 seconds. In some embodiments, the first surface is configured to contact an epicardial tissue and the second surface is configured to contact a pericardial tissue when the implantable device is implanted. In some embodiments, the method further includes detecting a cardiac arrhythmia by using one or more sensing electrodes disposed on the lead body of the cardiac lead.
In some embodiments, the method further includes cooling the first surface of the implantable medical device upon detection of the cardiac arrhythmia. In some embodiments, the step of making the incision further comprises making an incision into an epicardial space of the patient. In some embodiments, the step of securing the heat exchange module further comprises attaching a suture sleeve to the cardiac tissue, wherein the suture sleeve is removably coupled and/or slidably coupled to the lead body.
Particular embodiments of the subject matter described in this document can be implemented to realize one or more of the following advantages. First, transient therapeutic tissue cooling therapy can be delivered using the devices and methods described herein. In some embodiments, the therapeutic tissue cooling can advantageously be delivered using a system that is fully implantable and self-contained. Accordingly, the patient receiving treatment can be fully ambulatory, and can experience a lifestyle that is relatively unhindered by the presence of the implantable therapeutic cooling device. In some embodiments, heart conditions such as arrhythmias and others can be treated using the devices and methods provided herein. In some embodiments, arrhythmias can be treated relatively painlessly. In some embodiments, the devices include a pair of electrodes that are used to measure the impedance of the epicardial tissue. Such impedance measurements can be used to indicate a level of contact and/or pressure between the enclosure of the heat exchange module and the epicardial tissue. Accordingly, the pair of electrodes can be used to ascertain situations in which there is sufficient contact and/or pressure (between the heat exchange module and the epicardial tissue) to be able to provide effective or optimal cooling therapy to the epicardial tissue. Moreover, the pair of electrodes can be used to ascertain situations in which there is insufficient contact (between the heat exchange module and the epicardial tissue) to be able to provide effective cooling therapy to the epicardial tissue. In some cases, arrhythmia conditions can be treated in a minimally invasive fashion using the devices and methods provided herein. Such minimally invasive techniques can reduce recovery times, patient discomfort, and treatment costs.
Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Although methods and materials similar or equivalent to those described herein can be used to practice the invention, suitable methods and materials are described herein. In addition, the materials, methods and examples are illustrative only and not intended to be limiting.
The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other aspects, features, and advantages of the invention will be apparent from the description, the drawings, and the claims.
Like reference numbers represent corresponding parts throughout.
The present disclosure describes implantable medical devices and related methods for delivering cooling therapy. For example, described herein are methods and devices for treating atrial and/or ventricular fibrillation by cooling the epicardium.
Implantable cardiac defibrillators (ICDs) can aid saving the lives of at-risk individuals. A downside associated with ICD therapy, however, is the pain associated with defibrillation, whether shocks are delivered appropriately or inappropriately.
In some embodiments, heart conditions, such as arrhythmias and others, can be treated using the devices and methods provided herein. In some embodiments described herein, arrhythmias can be treated by an implantable system for painlessly terminating arrhythmias. The devices and methods provided herein permit prompt termination of atrial fibrillation almost immediately after an episode begins (to prevent persistence), and is effective irrespective of patient age and comorbidities.
The cardiac lead 102 includes a lead body 110 extending between a distal end 106 and a proximal end 108. The lead body 110 is a flexible elongate body. The lead body 110 includes an outer wall 112. The outer wall 112 defines an interior opening that is an elongate opening that extends along the length of the cardiac lead 102. The interior opening is sized to receive one or more electrical conductors (e.g., wires) that provide power and/or electrical signal connections to one or more components (e.g., sensors, heat pump, and/or heat sink) of the heat exchange module 104 and to one or more pairs of electrodes (e.g., the electrodes 138b and 138d). The lead body 110 is a multi-lumen tube. In some embodiments, the outer wall 112 defines one or more interior openings. For example, the lead body 110 defines a central lumen that is concentric with an outer diameter of the lead body 110. In some embodiments, the central lumen may be offset from the center of the outer diameter. The structure of the cardiac lead 102 (e.g., including the interior opening), together with a material choice (e.g., a pliable biocompatible material), provides the cardiac lead 102 with a flexibility that allows the lead body 110 to be elastically (e.g., reversibly) deformed (e.g., in bending). The flexibility of the cardiac lead 102 can advantageously facilitate positioning (e.g., by the surgeon) of the cardiac lead 102 during implantation. The interior opening of the lead body 110 and/or one or more electrical conductors can include an insulating material to support, insulate, and separate the electrical conductors to prevent current going through them from contacting other non-desired conductors (e.g., to prevent shorts and limit electrical leakage between the electrical conductors).
The lead body 110 of the cardiac lead 102 typically has a length of about 45 centimeters (cm) to about 75 cm (e.g., about 50 cm). The lead body 110 typically has an outer diameter of about 2.1 millimeters (mm) to about 3.1 mm (e.g., about 2.7 mm).
The lead body 110 is can be made of one or more materials typical of those used in the construction of implantable cardiac pacing and defibrillation leads. Example materials from which the lead body 110 may be made include silicone rubber, polyurethane, or silicone polyurethane copolymers. Example materials from which the insulating materials may be made include silicone rubber, polyurethane, polyether ether ketone (PEEK), polyurethane or polycarbonate.
The cardiac lead 102 includes a bifurcation 114 where the lead body 110 splits into a first portion 116 of the lead body 110 and a second portion 118 of the lead body 110. The bifurcation 114 is disposed along the lead body 110 in a location that is closer to the proximal end 108 than to the distal end 106 of the cardiac lead 102. In some embodiments, the bifurcation 114 can be positioned at a location that is about 75% distal from the distal end 106 of the cardiac lead 102. The first portion 116 of the lead body 110 includes a first lead connector 120, and the second portion 118 of the lead body 110 includes a second lead connector 122. The cardiac lead 102 can include one or more lead connectors disposed at the distal end 106. The first and second lead connectors 120, 122 are configured to connect to a control module (e.g., which can be an implantable module or a module that is positioned and used externally to the patient's body). For example, the first and second lead connectors 120, 122 provide the electrical and mechanical connection between the control module and the proximal end 108 of the cardiac lead 102. The control module can include components such as, but not limited to, a power source, a microprocessor, a memory storage, sensor circuitry (e.g., for sensing tissue impedance(s), temperature(s), heart rate, lead impedance, and the like), circuitry for delivering a voltage and/or a current output to stimulate the heart, and circuitry for delivering a voltage and/or current output to the Peltier device (heat pump) within the heat exchange module. The first and second lead connectors 120, 122 can provide an electrical and mechanical connection to one or more of any of the above-recited components of the control module.
When inserted into the control module, the one or more electrical conductors disposed within the first and second portions 116, 118 of the lead body 110 electrically couple the one or more components (e.g., electrodes, sensors, heat pump, etc.) of the heat exchange module 104 and the one or more pairs of electrodes (e.g., the pair of electrodes 138b and 138d) to the control module. In some embodiments, the control module can be an implantable cardiac device. For example, in some embodiments the implantable module is configured as an implantable cardioverter defibrillator (ICD) or a pacemaker. In other embodiments, this may be an external module (positioned and operationable/functional externally to the patient). In some embodiments, the cardiac lead 102 can be configured to not pace the heart and/or to not sense an ECG. In this case, the cardiac lead 102 may only deliver power to the Peltier device, may provide electrical signal connections to the pair of electrodes 138b and 138d, and may sense the temperature of the heat exchange module 104.
The one or more lead connectors include one or more lead terminal pins and one or more lead terminal rings. The first lead connector 120 includes a first terminal pin 124, and the second lead connector includes a second terminal pin 126. The first and second terminal pins 124, 126 provide the electrical connection between the control module and the cardiac lead 102. The first lead connector 120 further includes a first lead terminal ring 128a, a second lead terminal ring 128b, and a third lead terminal ring 128c, which are coupled to the first portion 116 of the lead body 110. The second lead connector 122 further includes a fourth lead terminal ring 128d, a fifth lead terminal ring 128e, and a sixth lead terminal ring 128f, which are coupled to the second portion 118 of the lead body 110. Each lead terminal ring 128a, 128b, 128c, 128d, 128e, 128f provides an electrical connection between the cardiac lead 102 and the control module.
In some embodiments, the first lead terminal ring 128a may be a return conductor that provides a path for the current in the system (e.g., in the implantable medical device 100) to flow back to the control module. In some examples, the second lead terminal ring 128b and the third lead terminal ring 128c may be lead terminals to one or more temperature sensors. In some embodiments, the fourth lead terminal ring 128d may correspond to the lead terminal to a sensing electrode. In some examples, the fifth lead terminal ring 128e may correspond to the lead terminal to a reference sensing electrode. The sensing and reference or common sensing electrodes 138b and 138d can be used to detect an electrical signal from a heart of the patient, and/or for measuring an impedance of epicardial tissue, as described in further detail below. The above-recited configurations are example configurations and each lead terminal ring may be connected to one or more different or same conductors. For example, in some embodiments, any one of the lead terminal rings can be configured to be or to connect to one or more conductors (e.g., a common/return conductor, one or more temperature sensors, a sensing electrode, a reference sensing electrode, a pacing conductor, a reference sensing electrode, or the like).
The electrical conductors connecting the first and second lead connectors 120, 122 to the one or more components (e.g., sensors, heat pump, and/or heat sink) of the heat exchange module 104 and to the pair of electrodes 138b and 138d, are typically made of one or more materials typical of those used in the construction of implantable cardiac pacing and defibrillation leads. Example materials from which the electrical conductors may be made include nickel cobalt chromium alloys such as MP35N®. Example materials from which the first and second lead terminal pins 124, 126 may be made include stainless steel alloys such as 316L, or Nickel Cobalt alloys such as MP35N®.
The lead body 110 includes a suture sleeve 134 disposed between the distal end 106 and the proximal end 108 of the cardiac lead 102. The suture sleeve 134 is configured to secure the implantable medical device 100 adjacent to a cardiac tissue. The suture sleeve 134 is removably coupled and/or slidably coupled to the lead body 110. The suture sleeve 134 is formed by a generally tubular portion defining a lumen that is configured to receive the cardiac lead 102. The suture sleeve 134 provides an aid for suturing and fixating the cardiac lead 102 at a desired position in the body (e.g., a portion of the heart, at the point of entry into a vein, or the like). Thus, the suture sleeve 134 is arranged to fixate the sleeve at a selected position along the lead body 110. The suture sleeve 134 includes a groove 136 bisecting the tubular portion of the suture sleeve 134 and configured to receive a suture. The groove 136 can be a circumferential groove or a circumferential recess that provides a guiding path onto which a suture can be tied and prevents the suture from sliding off the suture sleeve 134. In some embodiments, the lead body 110 includes a suture disk that can be used to seal an incision in the heart during implantation of the implantable medical device 100. The suture sleeve can couple with the suture disk to seal or close the incision in the heart.
The heat exchange module 104 is disposed at the distal end 106 of the lead body 110. The heat exchange module 104 is hermetically sealed and capable of cooling one of its surfaces. When implanted in the heart, the heat exchange module 104 can cool a portion of cardiac tissue (e.g., atrial tissue). In this manner, a cooling therapy can be delivered to a portion of a heart of a patient by cooling the cardiac tissue that is adjacent to, contacting, and/or in close proximity to a surface (e.g., the cold surface) of the heat exchange module 104. The cooling effect on the atrial tissue is believed to inhibit action potentials and allow the cardiac conduction system to return to sinus rhythm.
The heat exchange module 104 includes an enclosure 130 having a first surface 132 and a second surface. The heat exchange module 104 includes a heat pump (e.g., a Peltier element) located within the enclosure 130. The heat pump may include one or more thermoelectric cooling elements that use the Peltier effect to create a heat flux between the junction of two different types of materials. In contrast to the more commonly used vapor-compression refrigeration, Peltier cooling elements require no moving parts or circulating refrigerants, have a near infinite life, and can be made of a small size and flexible shape. These elements become thermally active when an electrical current is applied across them, with the temperature differential being a function of the current supplied into the system.
The first surface 132 of the heat exchange module 104 can be the cold surface, and the second surface of the heat exchange module 104 can be the hot surface, or vice versa. For example, the first surface 132 of the heat exchange module 104 is configured to be set to a first temperature that is less than a second temperature of the second surface of the heat exchange module. The first temperature can range from at least about 1 degree Celsius to about 37 degrees Celsius (e.g., about 1 degree Celsius to about 5 degrees Celsius, about 5 degrees Celsius to about 10 degrees Celsius, about 10 degrees Celsius to about 15 degrees Celsius, about 15 degrees Celsius to about 20 degrees Celsius, 20 degrees Celsius to about 25 degrees Celsius, 25 degrees Celsius to about 30 degrees Celsius, or 30 degrees Celsius to about 37 degrees Celsius). The second temperature can range from at least about 37 degrees Celsius to about 50 degrees Celsius (e.g., about 37 degree Celsius to about 40 degrees Celsius, about 40 degrees Celsius to about 45 degrees Celsius, or about 45 degrees Celsius to about 50).
The hot surface and the cold surface are physically separated from each other and interconnected with each other by an array of alternating n-type and p-type semiconductors. The different types of semiconductors have complementary Peltier coefficients. Semiconductors are soldered between hot surface and cold surface, such that the semiconductors are electrically in series and thermally in parallel. As DC electric current flows through the heat pump (e.g., via electrical leads that are electrically connected to the heat pump), heat from cold surface is transferred to the hot surface, so that the cold surface gets cooler while hot surface gets hotter.
The heat exchange module 104 can further include one or more insulating materials. For example, the peripheral edges of the heat exchange module 104 are insulated from enclosure 130 by an insulative barrier. The insulative barrier can be just an electrical insulator, or just a thermal insulator, or both an electrical and a thermal insulator. Insulative barrier can be made of any suitable insulative material such as, but not confined to, Teflon®, phenolic cast resins, nylon, glass, and the like.
The heat exchange module 104 is hermetically sealed within enclosure 130 to protect the heat exchange module 104 (e.g., an inner chamber defined by enclosure 130) from body fluid ingress when implanted. Any biologically inert, highly heat conductive metal can be used to construct the enclosure 130 such that the heat exchange module 104 is isolated from body fluids. Such a biologically inert, highly conductive metal for the enclosure 130 can include, but is not limited to, titanium, titanium alloys, stainless steel, stainless steel alloys, 316 stainless steel, and the like, and combinations thereof. The enclosure 130 is also equipped with a means of allowing electrical leads (e.g., cardiac lead 102) to exit the enclosure 130 through glass feedthroughs, for example.
The heat exchange module 104 includes a heat sink located within the enclosure 130. The heat sink includes a phase change material and a thermally conductive interface structure positioned between the heat pump and the phase change material. A phase change material can be used to absorb the heat generated by the heat exchange module 104 and subsequently facilitate the gradual dissipation of the heat in a safe and effective manner. The phase change material can be a material with a melting temperature in the range of between about human body core temperature (37° C.) and about 50° C. (e.g., about 37° C. to about 41° C., about 41° C. to about 45° C., about 45° C. to about 50° C.). Phase change materials that are applicable due to their high specific heat, high heat of fusion and melting temperature in the range of about 37° C. and 50° C. include, but are not limited to, paraffins. In some embodiments, the phase change material has a very low thermal conductivity (e.g., about 0.2 watt per meter per degree Celsius (W·cm−1·° C.−1)). Some desirable characteristics of the phase change material are low volume change with phase change, no toxicity, no corrosivity, and compatibility with the material of enclosure 130.
In some embodiments, the heat exchange module 104 includes one or more fixation filaments 142 (refer to
The one or more fixation filaments 142 are loop-shaped and biased in an outward direction so as to be biased to an open position but moveable rotationally inwardly when arms are closed. The one or more fixation filaments 142 are flexible and attached to the heat exchange module 104. When deployed, the one or more fixation filaments 142 provide compression against a target tissue (e.g., a tissue of the pericardial space), thereby pressing the cold surface of the heat exchange module 104 against the target tissue. The one or more fixation filaments 142 may be flexible enough to be rigidly attached to the heat exchange module 104 and resiliently deflectable inwardly, or they may be attached by a rotational coupling such as a pin or living hinge. The heat exchange module 104 can remain in place as an implant following deployment of the one or more fixation filaments 142.
The heat exchange module 104 can include one or more temperature sensors located within the enclosure 130. For example, the heat exchange module 104 includes a first temperature sensor and a second temperature sensor. The first and second temperature sensors are configured to measure a temperature of the first surface 132 and the second surface of the heat exchange module 104. The first and second temperature sensors are configured to measure a temperature of the cold and hot surfaces of the heat exchange module 104. As such, the first and second temperature sensors monitor the temperature of the heat exchange module 104. The first and second temperature sensors may monitor the temperature of a tissue surrounding the heat exchange module 104 once implanted. The first and second temperature sensors can provide feedback to a processor and/or controller (e.g., information regarding cooling efficacy, unwanted heating, and the like).
The pair of electrodes 138b and 138d are coupled to the heat exchange module 104 such that they are exposed on an outer surface of the enclosure 130. When the heat exchange module 104 is properly implanted within the pericardial sac, the pair of electrodes 138b and 138d abut against the epicardial tissue. In use, the pair of electrodes 138b and 138d can be utilized to measure impedance of the epicardial tissue between the pair of electrodes 138b and 138d. Such impedance measurements can be used by the electronics in the control module to determine whether there is sufficient contact and/or pressure between the heat exchange module 104 and the epicardial tissue to be able to delivery effective epicardial cooling therapy. For example, in some embodiments the measured impedance is compared to an impedance threshold value (which can be patient-specific and/or determined by a machine learning algorithm that is executed by the microprocessor in the control module) to determine whether sufficient contact and/or pressure exists between the heat exchange module 104 and the epicardial tissue. If the existence of insufficient contact and/or pressure is determined (e.g., as determined by a measured impedance being above a threshold level), an alarm or alert message/status can be issued by the control module. In some such cases, the delivery of the cooling therapy can be interrupted or not initiated in response to the measured impedance being above a threshold level.
The cardiac lead 102 can include one or more sensing electrodes (e.g., a sensing ring electrode). As shown in
The pair of electrodes 138b and 138d and the sensing electrode 140 are typically made of one or more materials with superior corrosion resistance and/or typical of those used in the construction of implantable cardiac pacing and defibrillation leads. Example materials from which the pair of electrodes 138b and 138d and the sensing electrode 140 may be made include platinum alloy materials.
The implantable medical device 100 further includes the control module (“CM”). The CM can be implanted within a body of the patient or can be external to the patient. The CM can be connected to the cardiac lead 102 via the first lead connector 120 and/or the second lead connector 122. The CM can supply power to the heat exchange module 104. When an episode of atrial arrhythmia is sensed (e.g., via the sensing electrode 140) and determined to meet therapy criteria, the CM supplies power to the heat exchange module 104. The Peltier element of the heat exchange module 104 cools a first exterior of the heat exchange module 104 to a set point temperature. The heat exchange module 104 further cools the cardiac tissue that is in contact with and in proximity to the heat exchange module 104. Upon completion of the cooling therapy, the ECG signal(s) is analyzed (e.g., via the sensing electrode 140) to determine the next step in the treatment.
The CM can include one or more of the following: a power supply, a controller, a processor, an ECG sensing means, a tissue impedance sensing means, a cardiac pacing means, a temperature sensing and controlling means, a means for storing and processing feedback information obtained from the electrodes and temperature sensors. The CM may contain a feedback control in its control module circuit for temperature monitoring and control of the hot and cold surface temperatures of the Peltier device. The feedback control may provide feedback to detect scenarios where inadequate temperature dissipation is occurring (e.g., when the hot surface of the heat exchange module 104 reaches a temperature of about 45 degrees Celsius to about 55 degrees Celsius). The feedback control may provide feedback where the device temperature is below the desired minimal temperature (e.g., when the cold surface of the heat exchange module 104 reaches a temperature of about 5 degrees Celsius to about 0 degrees Celsius). The feedback control may provide feedback when the device is not reaching a therapeutic temperature (e.g., the desired cold temperature for cooling therapy delivery) (e.g., when the cold surface of the heat exchange module 104 fails to reach a temperature of about 15 degrees Celsius to about 5 degrees Celsius). The implantable medical device 100 may include a sensor to detect a change in a voltage or an impedance in the one or more temperature sensors.
The implantable medical device 100 can include several programmable parameters such as a tissue impedance threshold, cooling temperature set point, and duration of cooling therapy. Programmable parameters of the cooling therapy may include a cooling temperature set point (e.g., about 5 degrees Celsius to about 15 degrees Celsius), a duration (e.g., on time) (e.g., about 5 seconds to about 60 seconds), a therapy target cooling temperature range (e.g., a minimum and a maximum therapeutic target temperature) (e.g., about 15 degrees Celsius to about 5 degrees Celsius), a maximum (e.g., a maximum threshold) cool temperature (corresponding to the cold surface of the heat exchange module 104) (e.g., about 5 degrees Celsius to about 0 degrees Celsius), a maximum (e.g., a maximum threshold) warm temperature (corresponding to the hot surface of the heat exchange module 104) (e.g., about 45 degrees Celsius to about 55 degrees Celsius), a maximum (e.g., a maximum threshold) energy or power delivery (e.g., about 200 Joules (J) to about 500 J). Safety termination of cooling therapy (e.g., the implantable medical device 100 is turned off) may result if one of the following conditions is met: the maximum cold threshold temperature is exceeded (corresponding to the cold surface of the heat exchange module 104) (e.g., about 5 degrees Celsius to about 0 degrees Celsius), the maximum hot threshold temperature is exceeded (corresponding to the hot surface of the heat exchange module 104) (e.g., about 45 degrees Celsius to about 55 degrees Celsius), the maximum threshold energy or power delivery is exceeded (e.g., about 200 J to about 500 J).
In some embodiments, the implantable medical device 100 can further include the capability of delivering a pacing therapy. A pacing mode can be activated to pace the atrium within a programmed time period after the detection of an atrial arrhythmia episode. In some embodiments, the pacing can be delivered concurrently with at least a portion of the cooling therapy, or can extend beyond the cooling therapy delivery. In some embodiments, the pacing mode stays off during the cooling therapy delivery. Multiple combinations of programmable pacing and cooling therapy modes are envisioned.
The implantable medical device 100 further includes a lead delivery tool designed to deploy the heat exchange module 104 onto the surface of a cardiac tissue (e.g., a pericardium). In one embodiment the delivery tool is tunneled into the pericardial space through an opening in a lower portion of the pericardial sac and is tunneled to the oblique sinus of the left atrium where the heat exchange module 104 is positioned and deployed.
Two example lead delivery tools 200, 300 are shown in
The tubular body of the sheath 202 typically has a length of about 14 centimeters (cm) to about 30 cm (e.g., about 16 cm). The tubular body of the sheath 202 typically has an outer diameter of about 2.5 millimeters (mm) to about 4.0 mm (e.g., about 4.5 mm). The tubular body of the sheath 202 typically has an inner diameter of about 2.0 millimeters (mm) to about 3.5 mm (e.g., about 3.0 mm). Example materials from which the sheath 202 may be made include common surgical tool materials such as, but not limited to, 304 or 316 stainless steel, or from a semi-rigid thermoplastic such as PEEK or polycarbonate.
The delivery tool 200 further includes a case 208 having a proximal end 210 and a distal end 212. The distal end 212 is formed to enclose or receive the heat exchange module 104 or a portion thereof. The distal end 212 can be generally rectangular or have a shape that is complementary to the shape of the heat exchange module 104. The distal end 212 of the case 208 is configured to secure the heat exchange module 104 while the cardiac lead 102 is being tunneled and positioned in the pericardial space. The fixation filaments 142 of the heat exchange module 104 are compressed and captured inside the distal end 212 of the case 208 when the heat exchange module 104 is loaded into the distal end 212 of the case 208. The case 208 includes a body 214 that is elongate, generally tubular, and is formed to receive the sheath 202. The body 214 extends from the proximal end 210 to the distal end 212.
The body 214 of the case 208 typically has a length of about 15 centimeters (cm) to about 28 cm (e.g., about 19 cm). The body 214 of the case 208 typically has an outer diameter of about 7.0 millimeters (mm) to about 10 mm (e.g., about 8.6 mm). The body 214 of the case 208 typically has an inner diameter of about 6.5 millimeters (mm) to about 9.5 mm (e.g., about 8.1 mm). Example materials from which the case 208 may be made include common surgical tool materials such as, but not limited to, 304 or 316 stainless steel, from a semi-rigid thermoplastic such as PEEK or polycarbonate, from a flexible or malleable material, or any combination thereof.
The sheath 202 is designed to fit against or abut the proximal portion 216 of the heat exchange module 104. In use, the sheath 202 is configured to secure the heat exchange module 104 in place while the case 208 is withdrawn. When the case 208 is withdrawn, the fixation filaments 142 of the heat exchange module 104 expand, exerting a spring tension that pushes against adjacent tissue, thereby securing the heat exchange module 104 in place within a cardiac region (e.g., the pericardial space). The sheath 202 is withdrawn once the heat exchange module 104 is secured in place by sliding the sheath 202 along the lead body 110 of the cardiac lead 102. When the sheath 202 is removed from a surgical site, the lead body 110 slides through the distal end 212 of the case 208 when the delivery tool 200 is removed.
A delivery tool may be substantially similar in construction and function in several aspects to the delivery tool 200 discussed above but can include an alternative case and sheath instead of case 208 and sheath 202. In some embodiments, the case and sheath may have an axial groove or notch. Such axial grooves or notches can provide a user (e.g., a clinician) with an alternative way to manipulate the heat exchange module 104 during implantation to achieve successful delivery and fixation to a portion of cardiac tissue (e.g., pericardial tissue).
In use, when the case 304 is withdrawn, the user can remove the sheath 302 from the retention clasp 310 by pulling the sheath 302 away from the retention clasp 310. Then, the fixation filaments 142 of the heat exchange module 104 expand, exerting a spring tension that pushes against adjacent tissue, thereby securing the heat exchange module 104 in place within a cardiac region (e.g., the pericardial space). The sheath 302 is withdrawn once the heat exchange module 104 is secured in place by sliding the sheath 302 along the lead body 110 of the cardiac lead 102 while the lead body 110 is slidably received in the axial groove 306.
In step 402, a clinician (e.g., a surgeon) makes an incision into a pericardial tissue of the patient. In some embodiments, the clinician makes an incision into a fibrous pericardium, a serous pericardium, a parietal pericardium, and/or a visceral pericardium. In some embodiments, the clinician makes an incision underneath the xiphoidal. In some embodiments, making the incision (e.g., step 402) further includes making an incision into an epicardial space of the patient.
In step 404, the clinician inserts the implantable medical device 100 described herein through the incision. The clinician may guide the implantable medical device 100 to a target area. For example, in some embodiments, the clinician guides the implantable medical device 100 to an oblique sinus of the heart. Delivering the implantable medical device 100 to the oblique sinus of the heart can advantageously provide a secure location where movement of the implantable medical device 100 is minimized. Additionally, delivering the implantable medical device 100 to the oblique sinus of the heart can advantageously target a cardiac tissue of interest for the treatment of the cardiac arrhythmia.
In step 406, the clinician secures the heat exchange module 104 of the implantable medical device 100 to a surface of a cardiac tissue using one of the delivery tools 200, 300 described herein. For example, the clinician withdraws the case 208 of delivery tool 200 while maintaining sheath 202 in place and abutting case 208 to the proximal portion 216 of the heat exchange module 104. In some embodiments, the clinician exerts a pushing force against the proximal portion 216 of the heat exchange module 104 to ensure the heat exchange module 104 remains in place while the fixation filaments 142 deploy. In some embodiments, the step of securing the heat exchange module (e.g., step 406) further includes attaching a suture sleeve 134 of the implantable medical device 100 to the cardiac tissue. In some embodiments, the suture sleeve is removably coupled and/or slidably coupled to the lead body 110.
In some embodiments, step 406 can also include using one or more pairs of electrodes (e.g., the pair of electrodes 138b and 138d as shown in
In some cases, a mathematical function is used to convert the measured epicardial tissue impedance into an indication/determination of whether the contact or pressure between the heat exchange module 104 and epicardial tissue is sufficient for effective delivery of cooling therapy. In some such cases, a machine learning algorithm, artificial intelligence, and/or neural network is used (e.g., by the control module) to develop such a mathematical function based on impedance data collected by the cooling therapy systems described herein. Accordingly, the machine learning technique, artificial intelligence, and/or neural network and mathematical function development by the control module can be patient-specific in some cases.
In step 408, if the measured impedance is below a threshold value that indicates sufficient contact or pressure between the heat exchange module 104 and epicardial tissue, a surface of the secured heat exchange module 104 is cooled to a therapeutic temperature for a therapeutic period of time. In some embodiments, the therapeutic temperature ranges from about 5 degrees Celsius to about 15 degrees Celsius. In some embodiments, the therapeutic period of time ranges from about 5 seconds(s) to about 60 seconds(s). In some embodiments, the surface that is cooled contacts the target tissue (e.g., a pericardial tissue such as, but not limited to, a visceral layer of a serous pericardial tissue that may include an epicardial tissue) prior to cooling. In some embodiments, as a first surface is cooled, a second surface of the heat exchange module 104 gradually warms up. In some embodiments, the second surface is configured to contact a cardiac tissue opposite of the target tissue (e.g., a pericardial tissue such as, but not limited to, a parietal layer of a serous pericardial tissue and/or a fibrous pericardial tissue) when the implantable medical device 100 is implanted.
In some embodiments, the methods described herein can further include detecting a cardiac arrhythmia by using the one or more (e.g., 1, 2, 3, 4, or more) sensing electrodes 140 disposed on the lead body 110 of the cardiac lead 102, or on the surface of the heat exchange module 104. In some embodiments, the one or more sensing electrodes 140 detect a cardiac arrhythmia prior to initiating the cooling therapy (e.g., cooling a first surface of the heat exchange module 104). In some embodiments, the one or more sensing electrodes 140 detect a cardiac arrhythmia after initiating the cooling therapy (e.g., cooling a first surface of the heat exchange module 104). In some embodiments, the methods described can further include cooling the first surface of the implantable medical device upon detection of the cardiac arrhythmia. For example, in some embodiments, ECG detection of a cardiac arrhythmia can trigger the initiation of the cooling therapy (e.g., cooling of the first surface of the heat exchange module 104). The cooling therapy may be applied for a prescribed period of time or in conjunction with continuous arrhythmia monitoring until the arrhythmia is terminated.
While the above-discussed implantable medical device 100 has been described and illustrated with respect to certain dimensions, shapes, arrangements, configurations, material formulations, and methods, in some embodiments, an implantable medical device that is otherwise substantially similar in construction and function to the implantable medical device 100 may include one or more dimensions, shapes, arrangements, configurations, and/or materials formulations that are different from the ones discussed above or may be used with respect to methods that are modified as compared to the methods described above. For example, while the implantable medical device 100 has been described and illustrated as including a cardiac lead 102 including a bifurcation 114 where the lead body 110 splits into a first portion 116 of the lead body 110 and a second portion 118 of the lead body 110, in some embodiments, a cardiac lead that is otherwise substantially similar in construction and function to the cardiac lead 102 may alternatively include a division point where the lead body splits into one or more portions of the lead body. In some embodiments, the lead body may split into 1, 2, 3, 4, 5, or more portions of the lead body.
While the implantable medical device 100 has been described and illustrated as including bifurcation 114 that can be positioned at a location that is about 75% distal from the distal end 106 of the cardiac lead 102, in some embodiments, the bifurcation 114 can be positioned at a location that is about 15 to about 30% distal from the distal end 106 of the cardiac lead 102. In some embodiments, the bifurcation 114 can be positioned at any location along the lead body 110 between the distal end 106 and the proximal end 108 of the cardiac lead 102.
While the implantable medical device 100 has been described and illustrated as including a first and second lead connectors 120, 122, in some embodiments, the implantable medical device 100 includes one or more lead connectors. In some embodiments, the implantable medical device 100 includes at least about 1 to about 5 (e.g. about 1 to 2, about 2 to 3, about 3 to 4, about 4 to 5) lead connectors. In some embodiments, the first lead connector 120 is a DF4 connector. In some embodiments, the first lead connector 120 is an IS4 connector. In some embodiments, the first lead connector 120 is an IS1 connector. In some embodiments, the first lead connector 120 is a lead connector that is different than a DF4, IS4, and/or IS1 connector. In some embodiments, the first lead connector 120 is connectable to a control module that can be a commercially available implantable module (e.g., an implantable cardioverter defibrillator (ICD), an implantable pulse generator (IPG), or the like). In some embodiments, the first lead connector 120 is a custom connector that is different than a DF4, IS4, and/or IS1 connector. In some embodiments, the second lead connector 122 is also a custom connector that is different than a DF4, IS4, and/or IS1 connector. In some embodiments, these are connectable to a commercially available implantable cardiac device (e.g., an ICD, an IPG, or the like).
While the implantable medical device 100 has been described and illustrated as including a first and second lead connectors 120, 122, in some embodiments, the implantable medical device 100 includes a single lead connector. In some embodiments, the single lead connector includes one or more connector or lead terminal rings. For example, in some embodiments, the single lead connector includes about 1 to about 10 lead terminal rings (e.g., about 1 to 2, 2 to 3, 3 to 4, 4 to 5, 5 to 6, 6 to 7, 7 to 8, 8 to 9, or 9 to 10 lead terminal rings). In some embodiments, any one of the lead terminal rings of the single lead connector can be configured to be or to connect to one or more conductors (e.g., a common/return conductor, one or more temperature sensors, a sensing electrode, a reference sensing electrode, a pacing conductor, a reference sensing electrode, or the like). In some embodiments, having a single lead connector results in having no bifurcation in the lead body.
While the implantable medical device 100 has been described and illustrated as including six lead terminal rings 128a, 128b, 128c, 128d, 128e, 128f, in some embodiments, the first and second lead connectors 120, 122 each include one or more lead terminal rings. In some embodiments, the first and second lead connectors 120, 122 each include about 1 to about 10 lead terminal rings (e.g., about 1 to 2, 2 to 3, 3 to 4, 4 to 5, 5 to 6, 6 to 7, 7 to 8, 8 to 9, or 9 to 10 lead terminal rings).
While the implantable medical device 100 has been described and illustrated as including an enclosure 130 of the heat exchange module 104 that is substantially rectangular, in some embodiments, it should be understood that other form factors are also envisioned. For example, in some embodiments, enclosure 130 has contoured surfaces rather than planar surfaces. In some such embodiments, enclosure 130 can be specifically contoured to interface with a particular anatomy of a patient.
While the implantable medical device 100 has been described and illustrated as delivering cooling therapy to a cardiac tissue, in some embodiments, the implantable medical device 100 may have the ability to also deliver anti-tachycardia pacing therapy to terminate certain arrhythmias. In some embodiments, the implantable medical device 100 may not have the ability to also deliver anti-tachycardia pacing therapy to terminate certain arrhythmias.
While this specification contains many specific implementation details, these should not be construed as limitations on the scope of any invention or of what may be claimed, but rather as descriptions of features that may be specific to particular embodiments of particular inventions. Certain features that are described in this specification in the context of separate embodiments can also be implemented in combination in a single embodiment.
Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable sub-combination. Moreover, although features may be described herein as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a sub-combination or variation of a sub-combination.
Similarly, while operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Moreover, the separation of various system modules and components in the embodiments described herein should not be understood as requiring such separation in all embodiments, and it should be understood that the described program components and systems can generally be integrated together in a single product or packaged into multiple products.
Particular embodiments of the subject matter have been described. Other embodiments are within the scope of the following claims. For example, the actions recited in the claims can be performed in a different order and still achieve desirable results. As one example, the process depicted in the accompanying figures do not necessarily require the particular order shown, or sequential order, to achieve desirable results. In certain implementations, multitasking and parallel processing may be advantageous.
This application claims the benefit of U.S. Provisional Application Ser. No. 63/531,143 filed Aug. 7, 2023. The disclosure of the prior application is considered part of (and is incorporated by reference in) the disclosure of this application.
| Number | Date | Country | |
|---|---|---|---|
| 63531143 | Aug 2023 | US |
