Patent Application
20210267627
The present invention relates to a medical transeptal crossing procedure.
The two upper chambers of the heart, the right and left atrium, are separated by the atrial septum. Transeptal punctures are becoming increasingly important with the realization of minimal invasive catheter based cardiac procedures. Mitral Valve repair, AF ablations and appendage closure all typically require a transeptal puncture. The puncture is being performed by crossing the intra atrial septum from the right atrium into the left atrium. This way the catheter traverses from the venous side to the arterial side. By entering the patient body through the venous side larger catheters can be utilized while minimizing the complication rate.
As disclosed by Hansen Medical in U.S. Pat. No. 7,753,853 (The '853 patent) a physiological parameter can be utilized to guide a transeptal puncture. However, as described in the '853 patent the septum must be at least partially traversed in order to detect a change of the physiologic parameter. The interventionalist typically accesses the left atrium by piercing the septum with a special needle, the Brockenbrough needle, under angiographic and often TEE guidance. This needle is hollow and enables detection of the blood pressure at the tip of the needle. Since right venous- and left atrial pressures are significantly different in value and flow pattern, the physician gets a visual confirmation that he has successfully accessed the left atrium by monitoring the pressure curves. However, this control mechanism is somewhat “after the fact” by confirming the needle position only, once the needle has entered the left atrium and is exposed to the higher blood pressure and arterial flow pattern. Even in experienced hands it does happen that the septum is punctured in the wrong location and or direction and structures like the aorta or the pericardium are penetrated, resulting in serious injury to the patient. While ICE (Intra Cardiac Echocardiography) or TEE (Trans Esophageal Echocardiography) imaging increases the safety of the transeptal puncture, such imaging is costly and time consuming. What would be desirable would be a simple method and apparatus to indicate the optimal needle position before the septum is partially or fully penetrated, without the use of additional imaging instrumentation.
Pursuant to the present invention, the above-mentioned procedural difficulties, with a change of the physiological parameter only after septal crossing, are addressed by utilizing a Doppler signal which detects left atrial blood flow without crossing, piercing or partially penetrating the septum. Preferably, one utilizes a pulsed Doppler approach to detect the left atrial blood flow characteristics through the septum, that is, from the right atrium, without a partial or complete crossing of the septum to ascertain a change of a physiological parameter. The left atrial flow pattern is detected through the septum without crossing or piercing the same. The amplitude of the Doppler signal will reach a maximum when the needle tip with the Doppler transceiver (Tx) is located adjacent to the fossa ovalis. In this way a safe transeptal crossing procedure is accomplished by ensuring that the needle points into the left atrium and is positioned at the thinnest portion of the septum (the fossa ovalis).
Pursuant to a further feature of the present invention, the depth and width of a Doppler sample volume is pre-selectable so that analysis of reflected ultrasound waves can detect not only left atrial blood flow and exclude accidentally penetrating neighboring structures like aorta or pericardium but can identify certain target areas such as a Pulmonary Vein in the case of PV isolation procedures or the mitral valve in case of MV repair or replacement. In this way not only a safe septal crossing is ensured but an optimal crossing angle to reach the target area can be determined.
Pursuant to an additional aspect of the invention, an ultrasound monitoring apparatus provides acoustic feedback to the clinician performing the transeptal puncture, facilitating the procedure since visual control or feedback is already overwhelming for the operator. Angiography, blood pressure, EKG, ICE, mapping of catheter position and catheter force all rely on visual displays. Therefore, the current invention preferably utilizes audio control to guide the transeptal puncture. The apparatus according to this aspect of the invention preferably includes an ultrasound transducer at the distal tip of a 14/1000 guidewire connected to a Doppler system operating in pulsed Doppler mode. (See, for example, products of Volcano Corp.)
As disclosed by Hansen Medical, a physiological parameter can be utilized to guide a transeptal puncture. However, as set forth in the '853 patent the septum needs to be at least partially traversed in order to detect a change of the physiologic parameter.
Unlike the device described in the '853 patent, an apparatus pursuant to the current invention does not require specialized equipment (14/1000 needle and wire with integrated sensor) for the transeptal puncture. A standard Brockenbrough needle can be utilized. Doppler guidance is achieved by advancing a flow wire (for example, of Volcano Corp.) through the standard hollow Brockenbrough needle.
Another application of the present invention enables coronary sinus access. A flow wire is introduced through a steerable sheath until the Doppler Tx reaches the distal opening of the sheath and an associated audible Doppler signal indicates significant venous flow towards the ultrasound transducer when the coronary sinus opening has been identified. Typically, a catheter is then advanced into the coronary sinus after the flow wire has been withdrawn. Other applications would be PFO (Patent Foramen Ovale) closure and appendage closure. In the case of PFO closure, again, a significant Doppler signal towards the transducer enables identification of the location of the repair site, while in the case of appendage closure an absence of a flow signal (or a chaotic flow pattern) confirms correct positioning.
An apparatus for enabling safe transeptal punctures, comprises a hollow needle, a flow wire or guidewire with a distal ultrasound transceiver (Tx) disposed in the lumen of the hollow needle, and a waveform generator operatively connected to the ultrasound transducer and configured to energize the ultrasound transducer to produce a pulsed ultrasound pressure wave of predetermined duration. A signal receiver is operatively connected to the ultrasound transducer, while a signal processor is operatively connected to the receiver and a storage medium such as an electronic storage unit. The signal processor is configured to record, in the storage medium, magnitudes of Doppler frequency changes of ultrasonic waves reflected from one or more predetermined sample volumes at respective predetermined distances from the ultrasound transducer in a selected ultrasound-transmissive medium.
Preferably, the apparatus further comprises an electro-acoustic transducer operatively connected to the signal processor to generate an audible signal varying with Doppler magnitude as dependent on a direction of propagation of the pulsed ultrasound pressure wave in the selected ultrasound-transmissive medium.
The waveform generator may be operatively connected to the signal processor for transmitting to the ultrasound transducer, in response to a control signal from the signal processor, a pulsed electrical signal inducing the ultrasound transducer to produce the pulsed ultrasound pressure wave of the predetermined duration. The signal receiver and the signal processor are configured to process Doppler frequency changes of incoming reflected pressure waves arriving at a predetermined interval after termination of the pulsed ultrasound pressure wave, whereby size and location of the predetermined sample volume may be preselected.
The apparatus may additionally comprising means such as a sheath for steering or orienting a distal end portion of the hollow needle and/or the Doppler flow wire to thereby adjust a direction of propagation of the pulsed ultrasound pressure wave and at least partially locations of the sample volumes.
The needle and (or) the flow wire are inserted through a lumen of the steerable sheath, thereby enabling accessing of a target structure in accordance with an audible Doppler flow signal produced by the electro-acoustic transducer.
The steerability of the sheath and the flow wire enables a precise location for the placement of a PFO closure device in accordance with an audible Doppler flow signal produced by the electro-acoustic transducer. In this application the sample volume depth is chosen to be a few mm's.
The predetermined sample volume typically has a depth of several centimeters, chosen so that not only left atrial blood flow is detectable but certain target areas can be identified, the target areas including Pulmonary Veins for PV isolation procedures and the mitral valve for MV repair or replacement, and the appendage in case of appendage closures. Also, structures to be avoided, particularly the Aorta, can be identified and a safe needle path can be chosen to avoid puncturing these structures.
An apparatus for enabling safe transeptal punctures comprises, in accordance with the present invention, a hollow needle, a flow wire or guidewire disposed in a lumen of the hollow needle, an ultrasound transducer mounted to a distal end portion of the flow wire or guidewire, and a waveform generator operatively connected to the ultrasound transducer and configured to energize the ultrasound transducer to produce a pulsed ultrasound pressure wave of predetermined duration. The apparatus further comprises a signal receiver operatively connected to the ultrasound transducer, an electronic storage unit, and a signal processor operatively connected to the waveform generator, the signal receiver and the electronic storage unit. The signal processor is configured to activate the signal receiver to commence detecting incoming ultrasonic pressure waves a predetermined interval after the waveform generator terminates energization of the ultrasound transducer and production of the pulsed ultrasound pressure wave. The signal processor is further configured to record in the electronic storage unit magnitudes of Doppler frequency changes of ultrasonic waves reflected from one or more predetermined sample volumes at respective predetermined distances from the ultrasound transducer in a selected ultrasound-transmissive medium. An electro-acoustic transducer is connected to the signal processor for generating, in response to signals therefrom, an audible signal varying with Doppler frequency shift magnitude in accordance with direction of propagation of the pulsed ultrasonic pressure wave from the ultrasound transducer into the left atrium so safe septal crossing is ensured and an optimal crossing angle to reach the target area can be determined.
Pursuant to another feature of the invention, the waveform generator is operatively connected to the signal processor for transmitting to the ultrasound transducer, in response to a control signal from the signal processor, a pulsed electrical signal inducing the ultrasound transducer to produce the pulsed ultrasound pressure wave of the predetermined duration, while the signal receiver and the signal processor are configured to process Doppler frequency changes of incoming reflected pressure waves arriving a predetermined interval after termination of the pulsed ultrasound pressure wave, whereby size and location of the predetermined sample volume may be preselected.
In accordance with a further feature of the invention, the signal processor and the electronic storage unit are configured for recording a pulsed Doppler signal generated at least several millimeters distal to a puncture tip of the hollow needle across the septum in the left atrium.
In a preferred embodiment of the present invention, the apparatus further comprises a steerable sheath. The flow wire or guidewire and the hollow needle are inserted through a lumen of the steerable sheath, thereby enabling (a) adjustment in a direction of propagation of the pulsed ultrasound pressure wave and at least partially locations of the sample volumes, (b) directing the needle pathway towards a target structure in accordance with an audible Doppler flow signal produced by the electro-acoustic transducer, and (c) determination of any of a plurality of precise locations in the left atrium for (i) pulmonary vein isolation procedures, (ii) mitral valve repair or replacement, (iv) appendage closures, and (iv) the placement of a PFO closure device in accordance with an audible Doppler flow signal produced by the electro-acoustic transducer.
A medical method in accordance with the present invention comprises inserting a distal end portion of a steerable sheath into a vascular system of a mammalian subject, and advancing the sheath through the vascular system of the mammalian subject so that the distal end portion is located in a right atrium of the mammalian subject, where a hollow needle with an ultrasound transducer at a distal end of the hollow needle is disposed in a lumen of the sheath. The method additionally comprises manipulating the steerable sheath, the hollow needle and the ultrasound transducer to position the ultrasound transducer in the right atrium within effective ultrasound transmission distance of a cardiac septum of the mammalian subject and so that a sharp distal tip of the hollow needle is spaced from a cardiac septum of the mammalian subject. Thereafter the ultrasound transducer is actuated to emit a pulsed ultrasonic pressure wave of predetermined duration, The method also comprises, monitoring incoming reflected pressure waves after a predetermined interval after termination of the pulsed ultrasonic pressure wave, calculating blood flow velocities from frequency shifts of the incoming reflected pressure waves, and operating an electro-acoustic transducer to generate an audible signal varying with Doppler frequency shift magnitude in accordance with direction of propagation and location at the fossa ovalis of the pulsed pressure wave from the ultrasound transducer into the left atrium.
The monitoring of the incoming reflected pressure waves may include detecting the incoming reflected ultrasound waves via the ultrasound transducer, the method further comprising controlling timing parameters of the pulsed ultrasonic pressure wave and of the monitoring of the incoming reflected pressure waves to ascertain blood flow velocity within a predetermined sample volume within the left atrium. The actuating of the ultrasound transducer includes energizing same to emit the pulsed ultrasonic pressure wave as a series of ultrasonic pressure wave pulses having a combined duration predetermined to provide the predetermined sample volume with a preselected length. The monitoring the incoming reflected pressure waves via the ultrasound transducer after the predetermined time interval serves to locate the sample volume at a predetermined distance from the ultrasound transducer in the left atrium of the mammalian subject.
Where the ultrasound transducer is attached to a distal end of a wire, providing the hollow needle with the ultrasound transducer includes inserting a distal end portion of the wire into a lumen of the hollow needle.
The actuating of the ultrasound transducer generally includes detecting reflected ultrasound waves via the ultrasound transducer, the method further comprising manipulating the hollow needle to move the distal end portion thereof through the cardiac septum in a direction determined in accordance with characteristics of the reflected ultrasound waves.
The method may further comprising steering the sheath to orient the distal end portion thereof in a desired direction towards an extremum of the audible signal and thereafter shifting the hollow needle distally through the steerable sheath and into the cardiac septum of the mammalian subject in the desired direction.
The method may further comprise accessing a coronary sinus in the right atrium in accordance with an audible Doppler flow signal produced by the electro-acoustic transducer.
A method for crossing a cardiac septum in a mammalian subject comprises, in accordance with the present invention, (i) providing a flow wire having a Doppler ultrasound transducer at a distal end thereof, (ii) inserting a distal end portion of the flow wire into a lumen of a hollow needle, (iii) advancing the hollow needle through a steerable sheath so that a distal end portion of the needle is located in a right atrium of the mammalian subject and so that the distal end portion of the needle is spaced from the cardiac septum without penetrating into the cardiac septum, (iv) manipulating the hollow needle and the flow wire to position the Doppler ultrasound transducer in the right atrium and facing towards the septum of the mammalian subject while that the distal end portion of the needle is spaced from the cardiac septum and does not penetrate into the cardiac septum, and (v) thereafter actuating the Doppler transducer to transmit pulsed Doppler signals to scan blood flow velocity within a predetermined sample volume located transeptally in a left atrium of the mammalian subject.
The actuating of the Doppler transducer typically includes inducing the Doppler transducer to produce a pulsed ultrasound pressure wave of a predetermined duration. The method further comprises (vi) monitoring incoming reflected pressure waves arriving a predetermined interval after termination of the pulsed ultrasound pressure wave, whereby size and location of the predetermined sample volume may be preselected to be located within the left atrium of the mammalian subject, and (vii) inserting the distal end portion of the hollow needle into the cardiac septum only after detection of blood flow velocity of a predetermined desired characteristic.
The method may further comprise steering or orienting a distal end portion of the flow wire to thereby adjust a direction of propagation of the pulsed ultrasound pressure wave and at least partially location of the sample volume.
Pursuant to further features of the invention, one inserts the hollow needle and the flow wire through a lumen of a steerable sheath and steers or orients the distal end portion of the flow wire b adjusting an orientation direction of a distal end of the steerable sheath, the inserting of the distal end portion of the hollow needle into the cardiac septum being in a direction controlled by adjusting the orientation of the distal end of the steerable sheath
The method preferably further comprises activating an electro-acoustic transducer to generate an audible signal varying with Doppler frequency shift magnitude in accordance with direction of propagation of the pulsed ultrasonic pressure wave from the ultrasound transducer into the left atrium and performing a surgical procedure taken from the group consisting of (i) pulmonary vein isolation procedures, (ii) mitral valve repair or replacement, (iv) appendage closures, and (iv) the placement of a PFO closure device, all carried out in accordance with an audible Doppler flow signal produced by the electro-acoustic transducer.
As depicted in
The flow wire 6 utilizes a pulsed Doppler principle (
In response to a control signal from processor 26, waveform generator 20 transmits an energization signal to transducer 4 inducing the transducer to emit a pulsed ultrasound pressure wave 7 of predetermined duration. The duration determines the length L of sample volume 8. The pulse train duration may be selectively adjusted by an operator via a sample-volume length control 28. A width W of any given sample volume 8 is determined by the transducer beam geometry.
Signal receiver 22 and signal processor 26 are further configured to process Doppler frequency changes of incoming reflected pressure waves 7′ arriving a predetermined time after termination of a pulsed ultrasound pressure wave output by transducer 4, so that distance or range of sample volume 8 may be selected in addition to length (L) and angular location (azimuth and elevation) of the sample volume. An operator may modify the distance or range D of sample volume 8 from transducer 4 by a sample-volume distance control 30 operatively connected to signal processor 26.
Further the depth D of the Doppler sample volume 8 in
Signal processor 26 may be operatively connected to an electronic storage unit or other storage medium 32, to record therein magnitudes of Doppler frequency changes of ultrasonic waves reflected from one or more predetermined sample volumes 8 at respective predetermined distances D (e.g., at least several millimeters) from the ultrasound transducer 4 in a selected ultrasound-transmissive medium such as the blood and heart tissues of a mammalian subject.
As depicted in
The ability to control orientation of the distal end of needle 5 enables identification of target areas such as Left Superior Pulmonary Vein (LSPV) 10 (
In a medical method as illustrated in the drawings, a distal end portion of needle 5 is inserted through a sheath into a vascular system of a mammalian subject, and advanced through the vascular system, typically through the vena cava VC so that the distal end portion of the needle is located in the right atrium RA of the subject. An interventional cardiologist or other operator manipulates needle 5, typically by steering or maneuvering sheath 36 together with needle 5 and transducer 4 therein, to position transducer 4 in right atrium RA within effective ultrasound transmission distance of cardiac or intra-atrial septum 3. Transducer 4 is activated to emit pulsed ultrasonic pressure waves configured to monitor blood flow velocities via frequency shifts of return ultrasonic waves reflected at least in part from moving blood in sample volume 8 inside left atrium LA of the subject. Preferably, electro-acoustic transducer 24 is operated to generate an audible signal varying with Doppler frequency shift and magnitude in accordance with direction of propagation of the pulsed ultrasound pressure waves 7 from ultrasound transducer 4 into left atrium LA.
The actuating of ultrasound transducer 4 during a Doppler procedure entails detecting reflected ultrasound waves 7′ via the transducer, controlling timing parameters of the emitted pulsed pressure waves 7 and the detecting of the reflected ultrasound waves 7′ to monitor blood flow velocity within sample volume 8 within left atrium LA.
The actuating of ultrasound transducer 4 further entails energizing the transducer to emit a series of ultrasonic pressure wave pulses 7 having a combined duration predetermined to provide sample volume 8 with length L.
In addition, the method comprises detecting the reflected ultrasound waves 7′ via transducer 4 after a predetermined time lag or delay after a termination of the series of ultrasonic pressure wave pulses 7, whereby the sample volume 8 is located at a predetermined distance D or range from transducer 4 in left atrium LA.
Wire 6 with ultrasound transducer 4 at the distal end thereof may be inserted into needle 5 after arrival of the distal end portion thereof in right atrium RA. However, wire 6 and needle 5 may be disposed inside sheath 36 during the insertion thereof through the vascular system of the subject.
It is contemplated that the medical method further comprises manipulating needle 5, optimally by steering sheath 36, to move the distal end portion of the needle through the cardiac septum 3 in a direction determined in accordance with characteristics of the reflected ultrasound waves 7′.
In an additional method, an operator orients a distal end portion (not labeled) of sheath 36 within the right atrium to orient same in a desired direction towards an extremum (maximum) of the audible signal produced by transducer 24, shifts the steerable sheath 36 in the desired direction and advances a catheter. In this way, one may access a coronary sinus in the right atrium.
It is to be noted that needle 5 is used only for transeptal punctures (TSPS) and not for pulmonary vein (PV) isolation or coronary sinus access.
The present invention provides a technique for obtaining an optimal sheath position to perform various conventional procedures, both in the right atrium alone and transeptally in the left atrium. In a PFO closure, one deploys an “umbrella” device in a septum and opens or expands closure elements on opposite sides of the septum in order to close a leak. This procedure is typically done from the right atrium. In this case needle 5 is not required at all since one does not require separate access to the left atrial side. The Doppler apparatus disclosed herein locates the leak and the sheath is positioned next to the hole and the closure device advanced into the hole.
Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims.
| Number | Date | Country | |
|---|---|---|---|
| 62980775 | Feb 2020 | US |
