WO2025108642A1

WO2025108642A1 - Implantable medical device for cardiac resynchronization therapy featuring an automatic adaptation of the stimulation parameters

Info

Publication number: WO2025108642A1
Application number: PCT/EP2024/079681
Authority: WO
Inventors: Thomas Dörr
Original assignee: Biotronik SE and Co KG
Current assignee: Biotronik SE and Co KG
Priority date: 2023-11-22
Filing date: 2024-10-21
Publication date: 2025-05-30
Anticipated expiration: 2026-05-22

Abstract

The invention relates to an implantable medical device for stimulating a human or animal heart that comprises a single electrode (20) comprising a proximal electrode pole (213) designed and arranged to be implanted within an atrium (2) of the heart (1) to be stimulated and a distal electrode pole (203) designed and arranged to be implanted within the septum (13) of the heart (1) to be stimulated. During operation, the implantable medical device performs the following steps: a) detecting (500), with the proximal electrode pole (213), an intrinsic atrial contraction of the heart (1) to be stimulated or stimulating (500), with the proximal electrode pole (213), the atrium (2) of the heart (1) to be stimulated; b) detecting (530), with the distal electrode pole (203), an intrinsic ventricular contraction of the heart (1) to be stimulated; c) determining (530) an intrinsic atrioventricular conduction time between i) the intrinsic atrial contraction or the stimulation of the atrium and ii) the intrinsic ventricular contraction; d) setting (550) a stimulated atrioventricular conduction time for stimulating the ventricle (3, 5) of the heart (1) to be stimulated with the distal electrode pole (203), the stimulated atrioventricular conduction time being shorter than the intrinsic atrioventricular conduction time.

Description

Implantable medical device for cardiac resynchronization therapy featuring an automatic adaptation of the stimulation parameters

The present invention relates to an implantable medical device according to the preamble of claim 1 and to a method for operating such a device according to the preamble of claim 14.

Implantable medical devices for stimulating a human or animal heart can feature different functionalities. To give an example, a CRT-D device is designed and arranged to accomplish a cardiac resynchronization therapy and a defibrillation of the patient’s heart. Such a CRT- D device typically has three electrodes, namely a combined right ventricular defibrillation and stimulation electrode, a right atrial stimulation and sensing electrode and a left ventricular coronary sinus electrode. Some manufacturers like Biotronik also offer a more complex right ventricular electrode that integrates the atrial sensing functionality into the right ventricular stimulation electrode. However, still in this case, two electrodes are necessary to be implanted in or at the patient’s heart. Thus, the solutions known from prior art require for a biventricular stimulation at least two ventricular electrodes. This requires a very big connecting block (header) of the stimulation generator of the implantable medical device being able to receive at least two, but typically even three electrode connectors. Such a big connecting block complicates the implantation of the implantable medical device.

If the implantable medical device is designed and arranged as a CRT-P device, i.e., a device for cardiac resynchronization therapy and pacing (but no defibrillation), the general setup is almost identical to the previously described CRT-D device. However, the CRT-P device does not comprise a defibrillation electrode. Nonetheless, CRT-P devices known from prior art typically require three distinct electrodes and an accordingly big connector block of the stimulation generator to connect these electrodes to the stimulation generator. If the implantable medical device is designed and arranged as a device for employing a two- chamber therapy, it is also necessary to implant two distinct electrodes into the patient’s heart. One electrode is guided into the right atrium, and the other is guided into the left ventricle. Both electrodes need to be connected with the stimulation generator, i.e., the implantable pulse generator. For this purpose, the implantable pulse generator typically comprises at least two connecting sockets. Like in case of a three-socket connecting box, this requires a significant amount of space.

As outlined above, prior art already teaches a specific variant of integrated electrodes that uses a proximal bipole for sensing electric signals in the patient’s right atrium. Then, this variant of the ventricular electrode already takes over the functionality of the atrial electrode. However, this electrode comprises a switch with two plugs to be able to be connected with a regular two-chamber stimulation system. Thus, the integration of the atrial electrode into the ventricular electrode does not alter the space requirement of the connector box of the stimulation generator.

If the sensing and detecting functionalities of an implantable medical device are integrated into one or two electrodes, there remains the requirement of providing a patient with an optimum pacing adapted to the patient’s health status.

It is an object of the present invention to provide an implantable medical device that has a small space requirement, allows an easy implantation, and enables a comprehensive cardiac resynchronization therapy.

This object is achieved with an implantable medical device for stimulating a human or animal heart having the features of claim 1.

Such an implantable medical device comprises a processor, a memory unit, a stimulation unit, and a detection unit. The stimulation unit is arranged and designed to stimulate a human or animal heart. The detection unit is designed and arranged to detect an electric signal of the same heart. In addition, the implantable medical device comprises a proximate electrode pole and a distal electrode pole forming part of the stimulation unit and of the detection unit. According to an aspect of the presently claimed and described implantable medical device, the proximal electrode pole is configured to be implanted within an atrium of the heart to be stimulated. In addition, the distal electrode pole is configured to be implanted within the septum of the heart to be stimulated. At this implantation site, the distal electrode pole is able to stimulate the left and the right ventricle of the heart to be stimulated, either simultaneously or individually, e.g. by left bundle branch area pacing (LBBAP). Thus, the distal electrode pole is able to bypass a left and/or right bundle branch block and thus to achieve an efficient pacing of the left and/or right ventricle even in case that the physiologic stimulus lines are no longer working or no longer working correctly.

The memory unit of the implantable medical device comprises a computer-readable program that causes the processor to perform the steps explained in the following when being executed on the processor.

In a first step, an intrinsic atrial contraction of the heart to be stimulated is detected with the proximal electrode pole. Alternatively, the atrium of the heart to be stimulated is stimulated with the proximal electrode pole to induce an atrial contraction.

In a further method step, an intrinsic ventricular contraction of the heart to be stimulated is detected with the distal electrode pole.

Subsequently, an intrinsic atrioventricular conduction time is determined. The atrioventricular conduction time is calculated between the intrinsic atrial contraction and the intrinsic ventricular contraction or between the stimulation of the atrium and the intrinsic ventricular contraction (being responsive to the stimulation of the atrium). In doing so, a factual measure reflecting the condition of the physiologic cardiac conduction system is obtained.

In a further method step, a stimulated atrioventricular conduction time is determined from the intrinsic atrioventricular conduction time and is set for subsequent ventricular simulations performed by the implantable medical device. This stimulated atrioventricular conduction time serves for triggering stimulation of a ventricle of the heart to be stimulated with the distal electrode pole. In this context, the stimulated atrioventricular conduction time is shorter than the intrinsic atrioventricular conduction time. By applying a stimulated atrioventricular conduction time that is shorter than the intrinsic atrioventricular conduction time, it is guaranteed that a ventricular stimulation, in particular a left ventricular stimulation, safely occurs prior to any intrinsic excitation that might still be possible even in case of a left bundle branch block. Thus, a shortening of the stimulated atrioventricular conduction time with respect to the intrinsic atrioventricular conduction time ensures a safe ventricular stimulation by the implantable medical device that affects both the right ventricle and the left ventricle of the heart to be stimulated. Consequently, an efficient cardiac resynchronization is achieved.

In particular, the implantable medical device is configured to carry out a cardiac resynchronization therapy, for instance, in case of a left or right bundle branch block. In case of a left or right bundle branch block, the right and left ventricular contractions occur temporally shifted to one another. In case of a left bundle branch block, the right ventricle contracts first followed by a contraction of the left ventricle. In case of a right bundle branch block, the left ventricle contracts first, followed by a contraction of the right ventricle.

In an embodiment, the memory unit of the implantable medical device comprises a computer-readable program that causes the processor to perform the steps explained in the following when being executed on the processor.

In a further method step, an intrinsic ventricular contraction of a first ventricle of the heart to be stimulated that occurs first after the intrinsic or induced atrial contraction is detected with the distal electrode pole. Subsequently, an intrinsic atrioventricular conduction time is determined. The atrioventricular conduction time is calculated between the intrinsic atrial contraction and the intrinsic ventricular contraction or between the stimulation of the atrium and the intrinsic ventricular contraction (being responsive to the stimulation of the atrium). In doing so, a factual measure reflecting the condition of the physiologic cardiac conduction system is obtained.

In a further method step, a stimulated atrioventricular conduction time is determined from the intrinsic atrioventricular conduction time and is set for subsequent ventricular simulations performed by the implantable medical device. This stimulated atrioventricular conduction time serves for triggering stimulation of a second ventricle of the heart to be with the distal electrode pole, wherein the second ventricle had been determined to contract temporally delayed from the contraction of the first ventricle. In this context, the stimulated atrioventricular conduction time is shorter than the intrinsic atrioventricular conduction time. By applying a stimulated atrioventricular conduction time that has been determined based on the first occuring ventricular contraction and which is shorter than the intrinsic atrioventricular conduction time, it is guaranteed that a ventricular stimulation of the second ventricle or of the septum of the heart safely occurs prior to any intrinsic excitation that might still be possible, i.e prior an intrinsic excitation of the first ventricle. Thus, a shortening of the stimulated atrioventricular conduction time with respect to the intrinsic atrioventricular conduction time ensures a safe ventricular stimulation by the implantable medical device that affects both the right ventricle and the left ventricle of the heart to be stimulated. Consequently, an efficient cardiac resynchronization is achieved.

In an embodiment, the implantable medical device comprises a single ventricular electrode, wherein the single ventricular electrode comprises the distal electrode pole which is used to determine the intrinsic atrioventricular conduction time and to stimulate the second ventricle.

In an embodiment, in case of any physiologic changes over time that changes the intrinsic atrioventricular conduction time, the implantable medical device is configured to adapt the stimulated atrioventricular conduction time to the determined and amended intrinsic atrioventricular conduction time so that the stimulation provided by the implantable medical device is able to keep track of the condition of the heart to be stimulated and to reflect a highly physiologic stimulation.

In an embodiment, the proximal electrode pole is configured to be implanted within the right atrium, and the computer-readable program causes the processor to perform the following steps when being executed on the processor: a) detecting, with the proximal electrode pole, an intrinsic right atrial contraction of the heart to be stimulated or stimulating, with the proximal electrode pole, the right atrium of the heart to be stimulated; b) detecting, with the distal electrode pole, an intrinsic right ventricular contraction of the heart to be stimulated; c) determining an intrinsic atrioventricular conduction time between i) the intrinsic right atrial contraction or the stimulation of the right atrium and ii) the intrinsic right ventricular contraction; d) setting a stimulated atrioventricular conduction time for stimulating the left ventricle of the heart to be stimulated with the distal electrode pole, the stimulated atrioventricular conduction time being shorter than the intrinsic atrioventricular conduction time. At this implantation site, the distal electrode pole is able to stimulate at least the left ventricle of the patient’s heart by left bundle branch area pacing (LBBAP). Thus, the distal electrode pole is able to bypass a left bundle branch block and thus to achieve an efficient pacing of the left ventricle even in case that the physiologic stimulus lines are no longer working or no longer working correctly.

In an embodiment, the proximal electrode pole is part of an atrial electrode which is implanted in the right atrium. The atrial electrode may be fixed to an atrial wall of the right atrium at its distal terminus. Moreover, the distal electrode pole may be part of a ventricular electrode which is implanted in the right ventricle. The ventricular electrode may be fixed in the septum of the heart.

In an embodiment, the proximal electrode pole and the distal electrode pole are part of a single electrode is implanted in the right atrium and the right ventricle and fixed in the septum of the heart. In this embodiment, the proximal electrode is not fixed to the atrial wall, but may be floating within the right atrium. In an embodiment, the proximal electrode pole is a single electrode pole. For sensing atrial signals and/or for stimulating the atrium of the heart to be stimulated, a housing of the implantable medical device can be used as counter electrode pole in this embodiment.

In an embodiment, the proximal electrode pole is a bipole. This proximal bipole is arranged and designed to detect an intrinsic atrial signal of the heart to be stimulated. After implantation of the single electrode of the implantable medical device, the proximal bipole is located within the right atrium so that the intrinsic atrial signal sensed by the proximal bipole can then be used to trigger the further stimulation pulses in order to deliver the LBBAP stimulation to the ventricle of the heart. In case of such a proximal bipole, it is not necessary to use a housing of the implantable medical device as counter electrode pole. Rather, one of the electrode poles of the proximal bipole can serve as counter electrode pole for the respective other electrode pole of the proximal bipole.

In an embodiment, the proximal bipole comprises two ring electrodes spaced apart from each other.

In an embodiment, the ventricular electrode or the single electrode comprises at its distal terminus a helix. This helix is designed and configured to be secured within cardiac tissue. For this purpose, the helix can be turned into the cardiac tissue, i.e., into the septum of the patient’s heart. After having implanted the ventricular electrode or the single electrode into the septum, in particular into the deep septum, it is possible to achieve an effective stimulation of the left ventricle even if no electrode is directly placed within the left ventricle or on an outside thereof (as in case of prior art left ventricular stimulation electrodes). An implantation of the distal electrode pole in the deep septum at a position distally of a left bundle branch block enables left bundle branch area pacing without requiring a separate left ventricular electrode.

In an embodiment, the helix is designed as fixed fixing helix. In another embodiment, the helix is designed as unscrewable fixing helix. Either design is particularly appropriate for fixing the ventricular electrode or the single electrode within the septum of the patient’s heart. In an embodiment, the distal electrode pole is a single electrode pole. For sensing and stimulation functionalities, a housing of the implantable medical device is then used as counter electrode pole for the single distal electrode pole.

In an embodiment, the distal electrode pole is a distal bipole. This distal bipole is arranged and designed to detect an intrinsic right ventricular signal of the heart to be stimulated. After implantation of the ventricular electrode or the single electrode of the implantable medical device, the distal bipole is located within the septum of the heart to be stimulated. At this implantation site, the distal bipole is well suited to provide stimulation pulses for LBBAP, as described above for a single distal electrode pole. In case of such a distal bipole, it is not necessary to use a housing of the implantable medical device as counter electrode pole. Rather, one of the electrode poles of the distal bipole can serve as counter electrode pole for the respective other electrode pole of the distal bipole.

In an embodiment, the above-mentioned helix forms at least a part of the distal bipole. Expressed in other words, at least one electrode pole (in particular both electrode poles) of the distal bipole is realized by the helix that is also used to secure the at least one electrode within the septum of the patient’s heart. This guarantees a very efficient energy transfer from the ventricular electrode or the single electrode into the surrounding cardiac tissue.

The distal bipole comprises a first electrode pole and a second electrode pole located proximally from the first electrode pole. In an embodiment, a distance between a distal end of the second electrode pole and a proximal end of the first electrode pole lies in a range of from 1 mm to 30 mm, in particular from 2 mm to 25 mm, in particular from 3 mm to 20 mm, in particular from 4 mm to 15 mm, in particular from 5 mm to 10 mm. Such a distance between the first electrode pole and the second electrode pole is particularly appropriate to allow a stimulation of different cardiac regions by the first electrode pole and the second electrode pole after the electrode has been implanted into the septum of the patient’s heart. Then, the first electrode pole can stimulate the left bundle branch, i.e., it can perform left bundle branch area pacing (LBBAP). Likewise, the second electrode pole can then stimulate the right bundle branch, i.e., it can perform right bundle branch area pacing (RBBAP). In addition, the second electrode pole can particularly well detect right ventricular signals in this position.

In an embodiment, the computer-readable program causes the processor to subtract a predeterminable absolute value from the determined intrinsic atrioventricular conduction time for determining the stimulated atrioventricular conduction time that is then set to be used for further stimulation events. In an embodiment, the absolute amount to be subtracted lies in a range of from 1 ms to 100 ms, in particular from 2 ms to 95 ms, in particular from

3 ms to 90 ms, in particular from 4 ms to 85 ms, in particular from 5 ms to 80 ms, in particular from 6 ms to 75 ms, in particular from 7 ms to 70 ms, in particular from 8 ms to 65 ms, in particular from 8 ms to 60 ms, in particular from 9 ms to 55 ms, in particular from 10 ms to 50 ms, in particular from 15 ms to 45 ms, in particular from 20 ms to 40 ms, in particular from 25 ms to 35 ms.

In an embodiment, the computer-readable program causes the processor to subtract a predeterminable relative value from the determined intrinsic atrioventricular conduction time for defining the stimulated atrioventricular conduction time that is set for subsequent stimulation events performed by the implantable medical device. In an embodiment, the relative value to be subtracted lies in a range of from 1 % to 50 %, in particular from 10 % to 50 %, in particular from 2 % to 45 %, in particular from 3 % to 40 %, in particular from

4 % to 35 %, in particular from 5 % to 30 %, in particular from 6 % to 25 %, in particular from 7 % to 20 %, in particular from 8 % to 15 %, in particular from 9 % to 10 %. A subtraction of such a relative value can adjust the intrinsic atrioventricular conduction time to result in the stimulated atrioventricular conduction time in an even more physiologic way than the subtraction of the absolute value typically is able to do.

In an embodiment, the computer-readable program causes the processor to regularly repeat the steps of a) detecting an intrinsic atrial contraction or stimulating the right atrium, b) detecting an intrinsic right ventricular contraction of the heart, c) determining the intrinsic atrioventricular conduction time, and d) setting the stimulated atrioventricular conduction time after a predeterminable number of cardiac cycles and/or after a predeterminable time interval. In doing so, a continuous adaptation of the stimulated atrioventricular conduction time to a possibly changing intrinsic atrioventricular conduction time can be achieved in a highly efficient manner. Such a regularly repetition can also be denoted as cyclic measuring.

In an embodiment, repetition of the precedingly explained method steps is performed after a predeterminable number of cardiac cycles, wherein the predeterminable number lies in a range of from 10 to 1000, in particular from 20 to 900, in particular from 30 to 800, in particular from 40 to 700, in particular from 50 to 600, in particular from 60 to 500, in particular from 70 to 400, in particular from 80 to 300, in particular from 90 to 200, in particular from 100 to 150.

In an embodiment, the repetition takes place after a predeterminable time period has passed, wherein the predeterminable time period lies in a range of from 10 seconds to 1000 seconds, in particular from 20 seconds to 900 seconds, in particular from 30 seconds to 800 seconds, in particular from 40 seconds to 700 seconds, in particular from 50 seconds to 600 seconds, in particular from 60 seconds to 500 seconds, in particular from 70 second to 400 seconds, in particular from 80 seconds to 300 seconds, in particular from 90 seconds to 200 seconds, in particular from 100 seconds to 150 seconds.

In an embodiment, the computer-readable program causes the processor to increase the stimulated atrioventricular conduction time to an amount that is longer than an expected intrinsic atrioventricular conduction time when the step of determining the intrinsic atrioventricular conduction time is to be performed. Such an increase of the stimulated atrioventricular conduction time results in a stimulated atrioventricular conduction time that is longer than the intrinsic atrioventricular conduction time. Consequently, a stimulation under application of the stimulated atrioventricular conduction time will not result in a cardiac contraction (since the heart is still in its refractory phase) or will at least not disturb a physiologic intrinsic ventricular contraction so that an updated value of the intrinsic atrioventricular conduction time can be easily recorded and used for defining an updated value of the stimulated atrioventricular conduction time.

In an embodiment, the computer-readable program causes the processor to detect the intrinsic ventricular contraction, in particular the intrinsic right ventricular contraction, by evaluating a far-field electrocardiogram that is measured between the distal electrode pole and a housing of the implantable medical device. Such an evaluation of the far-field electrocardiogram is a particularly appropriate possibility to detect the intrinsic cardiac activity with a single electrode and in particular with a single distal electrode pole. Thus, when relying on the evaluation of the far-field electrocardiogram, it is not necessary to provide a second distal electrode pole. This reduces the amount of electrode leads to be guided within the electrode and thus reduces the complexity of the single electrode of the implantable medical device.

In an embodiment, the implantable medical device comprises a shock coil that is located between the distal electrode pole and the proximal electrode pole. Such a shock coil can well be used for providing a defibrillation shock to the heart to be stimulated. Then, the implantable medical device can be used as CRT-D device. In this embodiment, the computer-readable program causes the processor to detect the intrinsic ventricular contraction, in particular the intrinsic right ventricular contraction, by evaluating a far-field electrocardiogram that is measured between the shock coil and a housing of the implantable medical device. A far-field electrocardiogram measured between the shock coil and the housing of the implantable medical device may comprise stronger signals than a far-field electrocardiogram measured between the distal electrode pole and the housing of the implantable medical device.

In an embodiment, the shock coil has a surface of at least 150 mm², in particular at least 175 mm², in particular at least 200 mm², in particular at least 225 mm², in particular at least 250 mm². Such a surface enables a sufficiently big shock pulse to be delivered by the shock coil to achieve an efficient cardiac defibrillation of the patient’s heart.

In an embodiment, the computer-readable program causes the processor to use an earliest time point of a ventricular excitation, in particular of a right ventricular excitation, as a measure for the intrinsic ventricular contraction, in particular for the intrinsic right ventricular contraction. Typically, this earliest time point of a ventricular excitation is the very beginning of the so-called QRS complex in an electrocardiogram. This QRS complex represents a ventricular excitation during a cardiac cycle. The beginning of the QRS complex as indication of the time point of the intrinsic ventricular contraction can be used both in case of evaluating a regular electrocardiogram (measured between two electrode poles that are both located on the single electrode) and in case of evaluating a far-field electrocardiogram (measured between an electrode pole located on the single electrode and a housing of the implantable medical device). The beginning of the QRS complex is a particularly appropriate time point for defining the start of the intrinsic ventricular contraction that is used for determining the intrinsic atrioventricular conduction time.

In an embodiment, the determination of the earliest time point of the ventricular excitation, in particular of the right ventricular excitation, is done via a morphologic signal evaluation. To give an example, the slope of a signal curve (also referred to as signal rise speed) in combination with a minimum value of the amplitude is a particularly appropriate morphologic measure to identify the earliest time point of the ventricular excitation from a measured signal curve like an electrocardiogram. As outlined above, the electrocardiogram can be a regular electrocardiogram or a far-field electrocardiogram.

In an embodiment, the computer-readable program causes the processor to perform the step of setting the stimulated atrioventricular conduction time only if the determined intrinsic atrioventricular conduction time lies within a predeterminable range. In case that the intrinsic atrioventricular conduction time lies outside the predeterminable range, the stimulated atrioventricular conduction time is set to a predeterminable fixed value. This embodiment prevents the setting of a non-physiologic stimulated atrioventricular conduction time in case that the determined intrinsic atrioventricular conduction time was calculated from an atypic cardiac cycle such as a cardiac cycle comprising an atrial extrasystole. Thus, this embodiment increases the safety of the implantable medical device and guarantees a high user-friendliness of the implantable medical device.

In an embodiment, the predeterminable range of the atrioventricular conduction time is a range of from 0.08 s to 0.25 s, in particular from 0.10 s to 0.25 s, in particular from 0.12 s to 0.22 s, in particular from 0.13 s to 0.20 s, in particular from 0.14 s to 0.18 s. In an embodiment, the computer-readable program causes the processor to set the stimulated atrioventricular conduction time only to a value lying within a predeterminable range. This embodiment increases the safety of the implantable medical device, too. It ensures that only physiologically sensible stimulated atrioventricular conduction times are applied by the implantable medical device during its operation.

In an embodiment, the allowable predeterminable range of the stimulated atrioventricular conduction time is a range of from 0.05 s to 0.20 s, in particular from 0.10 s to 0.15 s, in particular from 0.11 s to 0.12 s, in particular from 0.12 s to 0.13 s.

In an embodiment, the proximal electrode pole and the distal electrode pole are part of a single electrode, wherein the proximal electrode pole is designed and arranged to float, in its implanted state, within the right atrium.In an aspect, the present invention relates to a method for operating an implantable medical device according to the preceding explanations. This method comprises the steps explained in the following.

In a first step, an intrinsic atrial contraction of the heart to be stimulated is detected with the proximal electrode pole.

Subsequently, an intrinsic atrioventricular conduction time is determined. The atrioventricular conduction time is calculated between the intrinsic atrial contraction and the intrinsic ventricular contraction. In doing so, a factual measure reflecting the condition of the physiologic cardiac conduction system is obtained.

In a further method step, a stimulated atrioventricular conduction time is determined from the intrinsic atrioventricular conduction time and is set for subsequent ventricular simulations performed by the implantable medical device. This stimulated atrioventricular conduction time serves for triggering a stimulation of a ventricle of the heart to be stimulated with the distal electrode pole. In this context, the stimulated atrioventricular conduction time is shorter than the intrinsic atrioventricular conduction time. By applying a stimulated atrioventricular conduction time that is shorter than the intrinsic atrioventricular conduction time, it is guaranteed that a ventricular stimulation, in particular a left ventricular stimulation, safely occurs prior to any intrinsic excitation that might still be possible even in case of a left and/or right bundle branch block.

In an embodiment, the method for operating an implantable medical device comprises the following steps: a) detecting, with the proximal electrode pole, an intrinsic right atrial contraction of the heart to be stimulated; b) detecting, with the distal electrode pole, an intrinsic right ventricular contraction of the heart to be stimulated; c) determining an intrinsic atrioventricular conduction time between the intrinsic right atrial contraction and the intrinsic right ventricular contraction; d) setting a stimulated atrioventricular conduction time for stimulating the left ventricle of the heart to be stimulated with the distal electrode pole, the stimulated atrioventricular conduction time being shorter than the intrinsic atrioventricular conduction time.

In an aspect, the present invention relates to a medical method for providing a cardiac resynchronization therapy to a patient in need thereof. This method comprises the steps explained in the following.

In a first step, an intrinsic atrial contraction of the heart to be stimulated is detected with a proximal electrode pole of an electrode of an implantable medical device for stimulating a human or animal heart. Alternatively, an atrium of the heart to be stimulated is stimulated with the proximal electrode pole to induce an atrial contraction. An implantable medical device according to the preceding explanations is particularly appropriate for carrying out this method.

In a further method step, an intrinsic ventricular contraction of the heart to be stimulated is detected with a distal electrode pole that is part of the same electrode as the proximal electrode pole or part of a second (separate) electrode as explained above. In this context, the distal electrode pole is implanted within the septum of the patient’s heart. Subsequently, an intrinsic atrioventricular conduction time is determined. The atrioventricular conduction time is calculated between the intrinsic atrial contraction and the intrinsic ventricular contraction or between the stimulation of the atrium and the intrinsic ventricular contraction (being responsive to the stimulation of the atrium). In doing so, a factual measure reflecting the condition of the physiologic cardiac conduction system is obtained.

In a further method step, a stimulated atrioventricular conduction time is determined from the intrinsic atrioventricular conduction time and is set for subsequent ventricular simulations performed by the implantable medical device. This stimulated atrioventricular conduction time serves for triggering a stimulation of a ventricle of the patient’s heart with the distal electrode pole. In this context, the stimulated atrioventricular conduction time is shorter than the intrinsic atrioventricular conduction time.

Finally, the ventricle of the patient’s heart is stimulated with at least one stimulation pulse emitted by the distal electrode pole upon expiration of the stimulated atrioventricular conduction time. This at least one stimulation pulse serves for efficient cardiac resynchronization of the patient’s heart.

In a further embodiment, the method for providing a cardiac resynchronization comprises, in particular, the following steps: a) detecting, with the proximal electrode pole, an intrinsic right atrial contraction of the heart to be stimulated or stimulating, with the proximal electrode pole, the right atrium of the heart to be stimulated, wherein the proximal electrode pole is implanted within the right atrium of the patient’s heart; b) detecting, with a distal electrode pole of the electrode, an intrinsic right ventricular contraction of the heart to be stimulated, wherein the distal electrode pole is implanted within the septum of the patient’s heart; c) determining an intrinsic atrioventricular conduction time between i) the intrinsic right atrial contraction or the stimulation of the right atrium and ii) the intrinsic right ventricular contraction; d) setting a stimulated atrioventricular conduction time for stimulating the left ventricle of the patient’s heart, the stimulated atrioventricular conduction time being shorter than the intrinsic atrioventricular conduction time; e) stimulating the left ventricle of the patient’s heart with the distal electrode pole. All embodiments of the implantable medical device can be combined in any desired way and can be transferred either individually or in any arbitrary combination to each of the methods. Likewise, all embodiments of each of the methods can be combined in any desired way and can be transferred either individually or in any arbitrary combination to the implantable medical device and to the respective other method.

Further details of aspects of the present invention will be explained in the following making reference to exemplary embodiments and accompanying Figures. In the Figures:

Figure 1 shows a first embodiment of an implantable medical device implanted into a human heart;

Figure 2 shows a second embodiment of an implantable medical device implanted into a human heart;

Figure 3 shows a third embodiment of an implantable medical device implanted into a human heart;

Figure 4 shows a fourth embodiment of an implantable medical device implanted into a human heart;

Figure 5 schematically shows different components of an embodiment of an implantable medical device; and

Figure 6 shows a schematic flowchart of an embodiment of a method performed by an implantable medical device during operation.

Figure 1 shows a human heart 1 into which a biventricular electrode 20 and an atrial electrode 21 are implanted. Both the biventricular electrode 20 and the atrial electrode 21 are guided through the upper vena cava 12 into the right atrium 2. The biventricular electrode 20 is furthermore guided into the right ventricle 3 and fixed within the septum 13 separating the right ventricle 3 from the left ventricle 5. The biventricular electrode 20 is implanted in a deep septal position so that it can stimulate the left bundle branch of the human heart 1 and thus stimulate the left ventricle 5 even though it does not directly contact the left ventricle 5.

The atrial electrode 21 serves for detecting atrial signals and/or stimulating atrial tissue. For this purpose, the atrial electrode 21 comprises a first atrial electrode pole 211 and a second atrial electrode pole 212 that is located proximally of the first distal atrial electrode pole 211. The first atrial electrode pole 211 and the second atrial pole 212 form an atrial bipole 213 that is at least partially implanted into atrial tissue. This atrial bipole 213 represents a proximal electrode pole.

The biventricular electrodes 20 comprises a first distal electrode pole 201 and a second distal electrode pole 202 that is located proximally of the first distal electrode pole 201. The first distal electrode pole 201 and the second distal electrode pole 202 form a distal bipole 203 that represents a distal electrode pole. The distal bipole 203 is fixed within the septum 13 of the patient’s heart 1.

The biventricular electrode 20 and the atrial electrode 21 form part of a CRT-P device 22 that represents an implantable medical device. The CRT-P device 22 comprises a stimulation generator 23 (also referred to as housing) that comprises a header 230. The biventricular electrode 20 and the atrial electrode 21 are plugged into these electrode connector receiving sockets with their electrode connectors.

Figure 2 shows another embodiment of a CRT-P device 22 implanted into a human heart 1 that is very similar to the embodiment shown in Figure 1. In this and in all following Figures, similar elements will be denoted with the same numeral reference. The CRT-P device 22 comprises a biventricular electrode 20 that is guided through the upper vena cava 12 into the right atrium 2. The biventricular electrode 20 is furthermore guided into the right ventricle 3 and is fixed within the septum 13 separating the right ventricle 3 from the left ventricle 5. The biventricular electrode 20 is implanted in a deep septal position so that it can stimulate the left bundle branch of the human heart 1 and thus stimulate the left ventricle 5 even though it does not directly contact the left ventricle 5 (nor the left atrium 4). The biventricular electrode 20 comprises a distal electrode pole 203 having the shape of a helix and being fixed within the septum 13 of the patient’s heart 1.

The CRT-P device 22 further comprises a stimulation generator 23 that comprises a header 230. Since the biventricular electrode 20 is the only electrode of the CRT-P device 22, the header 230 is significantly smaller than a header of prior art stimulation generators since it only requires space for a single electrode connector receiving socket. The biventricular electrode 20 is plugged into this electrode connector receiving socket with its electrode connector.

The biventricular electrode 20 comprises an atrial electrode pole 213 that serves as proximal electrode pole. It is located on the biventricular electrode 20 such that it is placed in a floating position within the right atrium after implantation of the CRT-P device 22. The atrial electrode pole 213 serves for detecting atrial signals and/or stimulating atrial tissue.

During operation of the CRT-P device 22, a far-field electrocardiogram is measured between the distal electrode pole 203 and the stimulation generator 23 and/or between the atrial electrode pole 213 and the housing 23.

Figure 3 shows another embodiment of a CRT-P device 22 implanted into a human heart 1 that is very similar to the embodiment shown in Figure 2.

In contrast to the embodiment shown in Figure 2, the CRT-P device 22 of Figure 3 has a biventricular electrode 20 that comprises a distal bipole 203 and an atrial bipole 213.

The distal bipole 203 comprises a first distal electrode pole 201 and a second distal electrode pole 202 that is located proximally of the first distal electrode pole 201. The distal bipole 203 is fixed within the septum 13 of the patient’s heart 1 by means of a helix that forms the first distal electrode pole 201 of the distal bipole 203. The atrial electrode pole 213 of the biventricular electrode 20 is designed as atrial bipole 213. It comprises a first atrial electrode pole 211 and a second atrial electrode pole 212 that is located proximally of the first distal atrial electrode pole 211.

Instead of measuring a far-field electrocardiogram between the distal electrode pole 203 and the stimulation generator 23 and/or between the atrial electrode pole 213 and the stimulation generator 23 like in case of the embodiments shown in Figures 1 and 2, the distal bipole 203 and the atrial bipole 213 enable a measurement of a near-field electrocardiogram between the first distal electrode pole 201 and the second distal electrode pole 202 on the one hand and between the first atrial electrode pole 211 and the second electrode pole 212 on the other hand.

Figure 4 shows an embodiment of a CRT-D device 22 that is very similar to the CRT-P device 23 shown in Figure 3, but additionally comprises a shock coil 210 located on the biventricular electrode 20 between the distal electrode pole 203 and the atrial electrode pole 213. This shock coil 210 enables the provision of a defibrillation shock to the heart 1 in case that not only a resynchronization, but also a defibrillation is required. Thus, the biventricular electrode 20 of the embodiment shown in Figure 4 is able to provide a CRT-D therapy. Expressed in other words, this biventricular electrode 20 forms part of a CRT-D system 22 as example of an implantable medical device.

The shock coil 210 can also be used to measure a far-field electrocardiogram between the shock coil 210 and the stimulation generator 23. Thus, the embodiment shown in Figure 4 offers the possibility of measuring both near-field electrocardiograms (between the individual electrode poles of the distal bipole 203 or the atrial bipole 213) as well as between the shock coil 210 and the stimulation generator 23. In addition, it is possible to use either of the first distal electrode pole 201, the second distal electrode pole 202, the first atrial electrode pole 211, and the second atrial electrode pole 212 for measuring a far-field electrocardiogram against the housing 23 of the CRT-D device 22.

Figure 5 schematically illustrates individual components of an embodiment of an implantable medical device, such as of the embodiments shown in Figures 1 to 4, that are comprised within the stimulation generator 23 of the implantable medical device. The stimulation generator 23 houses a detection unit 231 (also referred to as sensing unit) that typically comprises an analog-to-digital converter, a bandpass filter, and an offset compensation. The detection unit 231 is operatively connected with a processor 232 that has access to a memory unit 233. The memory unit 233 serves for storing instructions for the processor 232 as well as data detected by the detection unit 231. The stimulation generator 23 further optionally comprises an evaluation unit 234 that can also be part of the processor 232 and that serves for extracting features from the detected cardiac electric signal. The stimulation generator 23 further comprises a stimulation unit 235 that serves for stimulating the heart from which the detection unit 231 detects electric signals. The biventricular electrode 20 (along with its electrode poles 203 and 213; confer Figures 1 to 4) forms part of the detection unit 231 and of the stimulation unit 235. Additionally, the stimulation generator 23 comprises a communication unit 236 that serves for data transfer to a (remote) programming device.

Figure 6 shows a schematic flowchart of a cyclic adaptation of the stimulated atrioventricular conduction time that is performed in an embodiment of the presently claimed and described implantable medical device, such as the implantable CRT-P devices 22 of Figures 1, 2 and 3 or the implantable CRT-D device 22 of Figure 4. The method depicted in Figure 6 will now be explained in more detail making also references to Figures 1 to 4.

In an atrial sensing/atrial pacing step 500, an intrinsic atrial contraction of the heart 1 is detected with the proximal electrode pole 213 of the biventricular electrode 20 of the CRT- P device 22 or the CRT-D device 22 (confer Figures 1 to 4 for more details on the devices). Alternatively, the proximal electrode pole 213 is used for stimulating the right atrium 2 of the patient’s heart 1 in this atrial sensing/atrial pacing step 500.

In a subsequent first decision step 510 it is determined whether the detected atrial rate is within a predetermined limit. If this is the case (indicated by a “y” meaning “yes”), the method will proceed to a second decision step 520. If this is not the case (indicated by an “n” meaning “no”), the stimulated atrioventricular conduction time to be applied by the implantable CRT-P/CRT-D device 22 is set to a programmed atrioventricular delay in a setting step 570. The CRT-P/CRT-D device 22 will then proceed with pacing for a predeterminable number of cardiac cycles (such as 60 cycles) in a pacing step 580 applying the programmed atrioventricular delay. Afterwards, the method will return to the initial atrial sensing/atrial pacing step 500.

Assuming that the first decision step 510 resulted in an atrial rate that was within the predeterminable limit, it will be determined in the second decision step 520 whether the sensed atrial signal is a regular atrial signal (y) or its to be considered as atrial extrasystole (n). In case of a detected (or suspected) atrial extrasystole, the method will proceed with the setting step 570 as explained above. If, however, the sensed atrial signal is considered to be a regular atrial signal, the method will proceed to an atrioventricular delay measuring step 530.

In this atrioventricular delay measuring step 530 an intrinsic atrioventricular conduction time (also referred to as atrioventricular delay) is determined. For this purpose, a non-physiologic long stimulated atrioventricular delay is set. Optionally, a ventricular trigger signal is suspended. Consequently, the pacing by the CRT-P/CRT-D device 22 will not occur at all or will only occur after an intrinsic (right) ventricular contraction. This enables measuring an intrinsic atrial ventricular conduction time.

In a third decision step 540, it is determined whether the measured intrinsic atrioventricular conduction time lies within a predeterminable time limit. If this is not the case (n), the method will proceed with the setting step 570 as indicated above. If, however, the measured intrinsic atrioventricular conduction time lies within the predeterminable time limit (y) the method proceeds to an adjustment step 550 in which the stimulated atrioventricular delay is set on the basis of the determined intrinsic atrioventricular delay. In this context, the stimulated atrioventricular delay is set to be shorter than the determined intrinsic atrioventricular delay. In doing so, it is ensured that the stimulation provided by the CRT- P/CRT-D device 22 is provided earlier than an intrinsic ventricular contraction would occur. Consequently, the provided stimulation will result in a synchronous contraction of the right ventricle 3 and the left ventricle 5 of the patient’s heart 1. The stimulation with the stimulated atrioventricular delay that was set in the adjustment step 550 is performed in a pacing step 560 for a predeterminable amount of cardiac cycles, e.g. for 60 cycles. Afterwards, the method returns to the atrial sensing/atrial pacing step 500. Then, a re-adjustment of the stimulated atrioventricular delay will be performed so that any physiologic changes of the intrinsic atrioventricular conduction time will be reflected in the stimulated atrioventricular conduction time in a highly timely manner.

Claims

1. Implantable medical device for stimulating a human or animal heart, comprising a processor (232), a memory unit (233), a stimulation unit (235) configured to stimulate a human or animal heart (1), a detection unit (231) configured to detect an electric signal of the same heart (1), and a proximal electrode pole (213) and a distal electrode pole (203) both forming part of the stimulation unit (235) and the detection unit (231), characterized in that the proximal electrode pole (213) is designed and arranged to be implanted within an atrium (2) of the heart (1) to be stimulated and the distal electrode pole (203) is designed and arranged to be implanted within a septum (13) of the heart (1) to be stimulated and in that the memory unit (233) comprises a computer-readable program that causes the processor (232) to perform the following steps when being executed on the processor (232): a) detecting (500), with the proximal electrode pole (213), an intrinsic atrial contraction of the heart (1) to be stimulated or stimulating (500), with the proximal electrode pole (213), the atrium (2) of the heart (1) to be stimulated; b) detecting (530), with the distal electrode pole (203), an intrinsic ventricular contraction of the heart (1) to be stimulated; c) determining (530) an intrinsic atrioventricular conduction time between i) the intrinsic atrial contraction or the stimulation of the atrium and ii) the intrinsic ventricular contraction; d) setting (550) a stimulated atrioventricular conduction time for stimulating the ventricle (3, 5) of the heart (1) to be stimulated with the distal electrode pole (203), the stimulated atrioventricular conduction time being shorter than the intrinsic atrioventricular conduction time.

2. Implantable medical device according to claim 1, characterized in that the proximal electrode pole is configured to be implanted within the right atrium, and in that the computer-readable program causes the processor (232) to perform the following steps when being executed on the processor (232): a) detecting (500), with the proximal electrode pole (213), an intrinsic right atrial contraction of the heart (1) to be stimulated or stimulating (500), with the proximal electrode pole (213), the right atrium (2) of the heart (1) to be stimulated; b) detecting (530), with the distal electrode pole (203), an intrinsic right ventricular contraction of the heart (1) to be stimulated; c) determining (530) an intrinsic atrioventricular conduction time between i) the intrinsic right atrial contraction or the stimulation of the right atrium and ii) the intrinsic right ventricular contraction; d) setting (550) a stimulated atrioventricular conduction time for stimulating the left ventricle (5) of the heart (1) to be stimulated with the distal electrode pole (203), the stimulated atrioventricular conduction time being shorter than the intrinsic atrioventricular conduction time.

3. Implantable medical device according to claim 1 or 2, characterized in that at least one of the proximal electrode pole (213) and the distal electrode pole (203) is a single electrode pole or a bipole.

4. Implantable medical device according to any of the preceding claims, characterized in that the computer-readable program causes the processor (232) to subtract a predeterminable absolute value from the determined intrinsic atrioventricular conduction time for defining the stimulated atrioventricular conduction time.

5. Implantable medical device according to any of the preceding claims, characterized in that the computer-readable program causes the processor (232) to subtract a predeterminable relative value from the determined intrinsic atrioventricular conduction time for defining the stimulated atrioventricular conduction time.

6. Implantable medical device according to any of the preceding claims, characterized in that the computer-readable program causes the processor (232) to regularly repeat steps a) to d) after a predeterminable number of cardiac cycles and/or after a predeterminable time interval.

7. Implantable medical device according to any of the preceding claims, characterized in that the computer-readable program causes the processor (232) to increase the stimulated atrioventricular conduction time to an amount that is longer than an expected intrinsic atrioventricular conduction time when step c) is to be performed.

8. Implantable medical device according to any of the preceding claims, characterized in that the computer-readable program causes the processor (232) to detect the intrinsic ventricular contraction by evaluating a far-field electrocardiogram that is measured between the distal electrode pole (203) and a housing (23) of the implantable medical device (22).

9. Implantable medical device according to any of the preceding claims, characterized in that the implantable medical device comprises a shock coil (210) located between the distal electrode pole (203) and the proximal electrode pole (213) and in that the computer-readable program causes the processor (232) to detect the intrinsic ventricular contraction by evaluating a far-field electrocardiogram that is measured between the shock coil (210) and a housing (23) of the implantable medical device

10. Implantable medical device according to claim 8 or 9, characterized in that the computer-readable program causes the processor (232) to use an earliest time point of a ventricular excitation as measure for the intrinsic ventricular contraction.

11. Implantable medical device according to the preceding claim, characterized in that the computer-readable program causes the processor (232) to determine the earliest time point of a ventricular excitation by a morphologic signal evaluation of the far- field electrocardiogram.

12. Implantable medical device according to any of the preceding claims, characterized in that the computer-readable program causes the processor (232) to perform step d) only if the determined intrinsic atrioventricular conduction time lies within a predeterminable range and to set the stimulated atrioventricular conduction time to a predeterminable fixed value if the determined intrinsic atrioventricular conduction time lies outside the predeterminable range.

13. Implantable medical device according to any of the preceding claims, characterized in that the proximal electrode pole (213) and the distal electrode pole (203) are part of a single electrode, wherein the proximal electrode pole is designed and arranged to float within the right atrium (2).

14. Method for operating an implantable medical device (22) according to any of the preceding claims, the method comprising the following steps: a) detecting (500), with the proximal electrode pole (213), an intrinsic atrial contraction of the heart (1) to be stimulated; b) detecting (530), with the distal electrode pole (203), an intrinsic ventricular contraction of the heart (1) to be stimulated; c) determining (530) an intrinsic atrioventricular conduction time between the intrinsic atrial contraction and the intrinsic ventricular contraction; d) setting (550) a stimulated atrioventricular conduction time for stimulating a ventricle (3, 5) of the heart (1) to be stimulated with the distal electrode pole (203), the stimulated atrioventricular conduction time being shorter than the intrinsic atrioventricular conduction time.

15. Method for providing a cardiac resynchronization therapy to a patient in need thereof, the method comprising the following steps: a) detecting (500), with a proximal electrode pole (213) of an electrode (20) of an implantable medical device (22) for stimulating a human or animal heart (1), in particular of an implantable medical device (22) according to any of claims 1 to 15, an intrinsic atrial contraction of the heart (1) to be stimulated or stimulating (500), with the proximal electrode pole (213), an atrium (2) of the heart (1) to be stimulated, wherein the proximal electrode pole (213) is implanted within the atrium (2) of the patient’s heart (1); b) detecting (530), with a distal electrode pole (203) of the electrode (20), an intrinsic ventricular contraction of the heart (1) to be stimulated, wherein the distal electrode pole (203) is implanted within the septum (13) of the patient’s heart (1); c) determining (530) an intrinsic atrioventricular conduction time between i) the intrinsic atrial contraction or the stimulation of the atrium and ii) the intrinsic ventricular contraction; d) setting (550) a stimulated atrioventricular conduction time for stimulating a ventricle (3, 5) of the patient’s heart (1), the stimulated atrioventricular conduction time being shorter than the intrinsic atrioventricular conduction time; e) stimulating (560) the ventricle (3, 5) of the patient’s heart with the distal electrode pole (203).