Apparatus and Method to Optimize Pacing Parameters

Abstract

An implantable medical device including a control unit, at least a right ventricular sensing unit and/or a right atrial sensing unit, wherein the right ventricular sensing unit is connected or can be connected to a right ventricular stimulation electrode lead having at least one electrode pole and a stimulation unit that is connected or can be connected to a multipolar left ventricular stimulation electrode lead having a plurality of electrode poles. The control unit is adapted to determine right atrioventricular conduction state and to cause selection of one of the plurality of electrode poles of the multipolar left ventricular stimulation electrode lead depending a respective determined right atrioventricular conduction state.

Claims

1. An implantable medical device comprising: a control unit, at least a right ventricular sensing unit and/or a right atrial sensing unit, wherein the right ventricular sensing unit is connected, or can be connected, to a right ventricular stimulation electrode lead having at least one electrode pole, and a stimulation unit that is connected, or can be connected, to a left ventricular stimulation electrode lead having a plurality of electrode poles, wherein the control unit is adapted to determine right-side atrioventricular conduction state and to provide selection of one of the plurality of electrode poles of the multipolar left ventricular stimulation electrode lead on the basis of the right-side atrioventricular conduction state.

2. The implantable medical device of claim 1, wherein for determining right side atrioventricular conduction state, the control unit is configured to determine whether a right ventricular sense-event (RVs) is present or not.

3. The implantable medical device according to claim 1, wherein the control unit is adapted to discriminate between at least two right-side atrioventricular conduction states, including a presence of intrinsic right-side atrioventricular conduction and/or an absence of right-side atrioventricular conduction and/or a disturbed right-side atrioventricular conduction state.

4. The implantable medical device according to claim 2, wherein the control unit is adapted to determine the presence or absence of an intrinsic right-side atrioventricular conduction depending on a temporal condition based on right-side ventricular activity with a preceding intrinsic or stimulated right atrial event (As; Ap).

5. The implantable medical device of claim 4, wherein the control unit is adapted to determine the presence of an intrinsic right-side atrioventricular conduction if a right ventricular sense-event (RVs) is recorded within a predetermined time period starting from an immediately preceding intrinsic or a stimulated right atrial event (As; Ap).

6. The implantable medical device of claim 5, wherein the duration of the predetermined time period depends on an actual heart rate or stimulation rate.

7. The implantable medical device according to claim 4, wherein the control unit is adapted to determine the presence of an intrinsic right atrioventricular conduction if a number of recorded sensed right ventricular events exceeds a predetermined minimum, wherein each sensed right ventricular event of the number of recorded sensed right ventricular events relates to a respective right atrial event (As; Ap) of sequence of immediately consecutive atrial events.

8. The implantable medical device according to claim 1, wherein the control unit is adapted to determine and/or select the left ventricular electrode that corresponds with the longest conduction time to any of the left ventricular electrodes, starting from a right ventricular event.

9. The implantable medical device according to claim 1, wherein the control unit is adapted to: select different left ventricular electrodes for different right atrioventricular conduction states, associate a selected left ventricular electrode to the corresponding right atrioventricular conduction state, and store the information on the association in a memory circuit.

10. The implantable medical device according to claim 1, wherein the implantable medical device is configured to determine right atrioventricular conduction state and select of one of the plurality of electrode poles of the multipolar left ventricular stimulation electrode lead automatically in a periodical manner, or wherein determination of right atrioventricular conduction state and selection of one of the plurality of electrode poles of the multipolar left ventricular stimulation electrode lead is performed according to a manual process via receiving input from a user, or wherein determination of right atrioventricular conduction state and selection of one of the plurality of electrode poles of the multipolar left ventricular stimulation electrode lead is performed according to a combination of an automatic and manual process.

11. The implantable medical device according to claim 1, wherein the control unit is adapted to cause selection of more than one of the plurality of electrode poles of the multipolar left ventricular stimulation electrode lead depending on a respective determined right-side atrioventricular conduction state.

12. The implantable medical device of claim 2, wherein the control unit is adapted: to select that left ventricular electrode for left ventricular pacing that provides the longest conduction time between a right ventricular sensed event to a left ventricular sensed event, if right atrioventricular intrinsic conduction exists, and to select that left ventricular electrode for left ventricular pacing that provides the longest conduction time between a right ventricular paced event to a left ventricular sensed event, if no right atrioventricular intrinsic conduction exists.

13. The implantable medical device according to claim 1, wherein the control unit is adapted to determine the presence or absence of an intrinsic right atrioventricular conduction on a beat-to-beat basis.

14. The implantable medical device according to claim 1, wherein the control unit is connected to a quadri-polar left ventricular electrode lead.

15. The implantable medical device according to claim 1, wherein the implantable medical device is a heart stimulator that is adapted to provide a cardiac resynchronization therapy.

Description

DESCRIPTION OF THE DRAWINGS

[0075] The above and other aspects, features and advantages of the present invention will be more apparent from the following more particular description thereof, presented in conjunction with the following drawings wherein:

[0076] FIG. 1 shows a three chamber bi-ventricular implantable cardioverter/defibrillator (ICD).

[0077] FIG. 2 is a schematic diagram of an embodiment of the device modules of the ICD of FIG. 1.

[0078] FIG. 3A provides an example illustration where intrinsic right-side conduction instates a longest RV to LV conduction condition at the second (from top) left ventricular electrode pole.

[0079] FIG. 3B provides an example illustration where a lack of intrinsic right-side conduction instates a longest RV to LV conduction condition at the topmost left ventricular electrode pole.

[0080] FIG. 4 illustrates inter-ventricular conduction times in case of an intact intrinsic right-side conduction.

[0081] FIG. 5 illustrates inter-ventricular conduction times in case of compromised intrinsic right-side conduction, involving a paced right ventricular event.

[0082] FIGS. 6A to 6C illustrate the effect of poor (a and b) and optimal (c) ventricular coordination.

DETAILED DESCRIPTION

[0083] The following description is of the best mode presently contemplated for carrying out the present invention. This description is not to be taken in a limiting sense, but is made merely for the purpose of describing the general principles of the present invention. The scope of the present invention should be determined with reference to the claims.

[0084] In FIG. 1 the implantable medical device (also referred to as implantable cardiac device) is a three chamber biventricular pacemaker and cardioverter/defibrillator 100 that is connected to pacing/sensing leads 110, 112 and 114 placed in a heart is illustrated.

[0085] As shown in FIG. 1, the preferred embodiment is to couple the disclosed technology with an implantable bi-ventricular defibrillator.

[0086] The implantable medical device 100 is electrically coupled to heart by way of leads 110, 112 and 114.

[0087] Lead 110 is a right ventricular electrode lead that has a pair of ventricular stimulation and sensing electrodes 121 and 122 that are in contact with the right ventricle of heart. In case the implantable medical device includes a defibrillation function, a ventricular defibrillation shock coil 123 is arranged on lead 110.

[0088] Lead 112 is a right atrial electrode lead that has a pair of right atrial electrodes 131 and 132 that are in contact with the right atria of the heart.

[0089] Electrodes 121 and 131 are tip electrodes at the very distal end of leads 110 and 112, respectively. Electrode 131 is a right atrial tip electrode RA Tip and electrode 121 is a right ventricular tip electrode. Electrodes 122 and 132 are ring electrodes in close proximity but electrically isolated from the respective tip electrodes 121 and 131. Electrode 132 forms a right atrial ring electrode RA Ring and electrode 122 forms a right ventricular ring electrode RV Ring. Ventricular defibrillation shock coil 123 is a coil electrode providing a relatively large geometric area when compared to the stimulation electrodes 121, 122, 131 and 132.

[0090] Lead 114 is a left ventricular electrode lead passing through the coronary sinus of heart and having a left ventricular tip electrode LV TIP 141 and left ventricular ring electrodes LV RING 142, 143 and 144. Further, a left ventricular defibrillation shock coil (not shown) may be arranged on lead 114. It is noted that the number of left ventricular ring electrodes may vary depending on the electrode lead that is used. In the context of FIGS. 1 and 2, one left ventricular ring electrode LV-RING is referred to the acts as pars pro toto.

[0091] Implantable medical device 100 has a case 102 made from electrically conductive material such as titanium that can serve as a large surface electrode.

[0092] The plurality of left ventricular electrodes 141, 142, 143 and 144 allow for a number of different pacing sites for stimulating the left ventricle.

[0093] FIG. 2 illustrates a simplified block diagram of an implantable medical device 100. During operation of the implantable medical device 100, electrode leads 110, 112 and 114 are connected to respective output/input terminals of the implantable medical device 100 as indicated in FIG. 2 and carry stimulating pulses to the tip electrodes 121, 131 and one of 141, 142, 143 and 144 from a right atrial stimulation pulse generator RA-STIM 50, a right ventricular pulse generator RV-STIM 52 and a left ventricular pulse generator LV-STIM 54, respectively. Selection of one of left ventricular electrode poles 141, 142, 143 and 144 as the left ventricular stimulation electrode pole is done by a control unit 62 via selection unit 70. Control unit 62 selects the left ventricular stimulation electrode based on a respectively determined right atrioventricular conduction state, i.e., whether there is intrinsic right ventricular conduction or not.

[0094] For assessing conduction from the right atrium to the right ventricle of the heart in the context of the present invention, the implantable medical device 100 requires atrial and/or ventricular sensing support and capacity. Such capacity include electric components (as, e.g., aforementioned right atrial electrode lead 112 which is in direct contact with the heart tissue in the right atrium, or a lead having an electrode for sensing in the right atrium without direct contact with the heart tissue, as for example a right side ventricular lead having a floating electrode which is located in the atrium) as well as respective software units for sensing, processing and evaluation of acquired signals.

[0095] Further, electrical signals from the right atrium are carried from the electrode pair 131 and 132, through the lead 112, to the input terminal of a right atrial channel sensing stage RA-SENS 56; and electrical signals from the right ventricle are carried from the electrode pair 121 and 122, through the lead 110, to the input terminal of a right ventricular sensing stage RV-SENS 58. Likewise electrical signals from the left ventricle are carried from the electrode pairs on lead 114, to the input terminal of a left ventricular sensing stage LV-SENS 60.

[0096] A defibrillation shock generator RV-SHOCK 72 is connected to the shock coil 123 via right ventricular electrode lead 110.

[0097] Controlling the implantable medical device 100 is a control unit CTRL 62 that is connected to sensing stages RA-SENS 56, RV-SENS 58 and LV-SENS 60, to stimulation pulse generators RA-STIM 50, RV-STIM 52 and LV-STIM 54, to defibrillation shock generator RV-SHOCK 72 and to selection unit LV SEL 70. Control unit CTRL 62 receives the output signals from the atrial sensing stage RA-SENS 56, from the right ventricular sensing stage RV-SENS 58 and from the left ventricular sensing stage LV-SENS 60. The output signals of sensing stages RA-SENS 56, RV-SENS 58 and LV-SENS 60 are generated each time that a P-wave representing an intrinsic atrial event or an R-wave representing an intrinsic ventricular event, respectively, is sensed within the heart. An As-signal is generated, when the atrial sensing stage RA-SENS 56 detects a P-wave and a RVs-signal is generated, when the right ventricular sensing stage RV-SENS 58 detects an R-wave.

[0098] In general, control unit 62 is preferably adapted to monitor right atrioventricular conduction behavior, in particular the time sequence of atrial events (As or Ap) and the next ventricular event in order to determine whether there is an intrinsic right-ventricular following an atrial event within a certain time.

[0099] When control unit 62 receives a RVs-signal within a predetermined time period starting from an As-signal or an Ap event, control unit 62 switches in an operation mode for intact intrinsic atrioventricular (AV) conduction and delivery of a right ventricular pacing pulse is inhibited. Otherwise, control unit 62 switches in an operation mode corresponding to a lack of intrinsic atrioventricular (AV) conduction. As a consequence a right ventricular pacing pulse may be delivered and the pacing site for the left ventricle may be altered by selecting a different left ventricular electrode for delivery of the left ventricular pacing pulse than in the operation mode for intact intrinsic atrioventricular (AV) conduction.

[0100] Control unit CTRL 62 also generates stimulation signals that are sent to the atrial stimulation pulse generator RA-STIM 50, the right ventricular stimulation pulse generator RV-STIM 52 and the left ventricular stimulation pulse generator LV-STIM 54, respectively. These stimulation signals are generated each time that a stimulation pulse is to be generated by the respective pulse generator RA-STIM 50, RV-STIM 52 or LV-STIM 54. The atrial stimulation signal is referred to simply as the RA-pulse, and the ventricular stimulation signal is referred to as the RV-pulse or the LV-pulse, respectively. During the time that either an atrial stimulation pulse or ventricular stimulation pulse is being delivered to the heart, the corresponding sensing stage, RA-SENS 56, RV-SENS 58 and/or LV-SENS 60, is typically disabled by way of a blanking signal presented to these amplifiers from the control unit CTRL 62, respectively. This blanking action prevents the sensing stages RA-SENS 56, RV-SENS 58 and LV-SENS 60 from becoming saturated from the relatively large stimulation pulses that are present at their input terminals during this time. This blanking action also helps prevent residual electrical signals present in the muscle tissue as a result of a stimulation pulse delivered from implantable medical device 100 from being interpreted as P-waves or R-waves.

[0101] Control unit CTRL 62 comprises circuitry for timing ventricular and/or atrial stimulation pulses according to an adequate stimulation rate that can be adapted to a patient's hemodynamic need as pointed out below. Timing is assisted by clock 74 connected to control unit 62.

[0102] Still referring to FIG. 2, the implantable medical device 100 includes a memory circuit MEM 64 that is coupled to the control unit CTRL 62 over a suitable data/address bus ADR. This memory circuit MEM 64 allows certain control parameters, used by the control unit CTRL 62 in controlling the operation of the implantable medical device 100, to be programmably stored and modified, as required, in order to customize the implantable medical device's operation to suit the needs of a particular patient. Such data includes the basic timing intervals used during operation of the implantable medical device 100 and AV delay values and hysteresis AV delay values in particular.

[0103] Further, data sensed during the operation of the implantable medical device 100 may be stored in the memory MEM 64 for later retrieval and analysis.

[0104] A telemetry circuit TRX 66 is further included in the implantable medical device 100. This telemetry circuit TRX 66 is connected to the control unit CTRL 62 by way of a suitable command/data bus. Telemetry circuit TRX 66 allows for wireless data exchange between the implantable medical device 100 and some remote programming or analyzing device which can be part of a centralized service center serving multiple implantable medical devices. Telemetry circuit TRX 66 allows data communication with an external device 160 (see FIG. 1).

[0105] In FIG. 2, those portions of the implantable medical device 100 that interface with the right atrium, e.g., the lead 112, the P-wave sensing stage RA-SENS 56, the atrial stimulation pulse generator RA-STIM 50 and corresponding portions of the control unit CTRL 62, are commonly referred to as the atrial channel. Similarly, those portions of the implantable medical device 100 that interface with the right ventricle, e.g., the lead 110, the R-wave sensing stage RV-SENS 58, the ventricular stimulation pulse generator RV-STIM 52, and corresponding portions of the control unit CTRL 62, are commonly referred to as the right ventricular channel. Accordingly, the implantable medical device may include a left ventricular lead having electrodes with sensing and/or pacing functionalities. Respectively, those portions of the implantable medical device 100 that are coupled to signals from the left ventricle and corresponding portions of the control unit CTRL 62, can be referred to as the left ventricular channel.

[0106] In order to be able to detect periods of physical activity of a patient indicating that the patient is awake and in order to allow rate adaptive pacing in a DDDR or a DDIR mode, for example, the implantable medical device 100 further includes a physiological sensor ACT 68 that is connected to the control unit CTRL 62 of the implantable medical device 100. While this sensor ACT 68 is illustrated in FIG. 2 as being included within the implantable medical device 100, it is to be understood that the sensor may also be external to the implantable medical device 100, yet still be implanted within or carried by the patient. A common type of sensor is an accelerometer, such as an inertial proof mass mounted within the implantable medical device. Other types of physiologic sensors are also known, such as, for example, sensors that sense the oxygen content of blood, respiration rate, blood pH, intracardiac impedance changes, and the like. The type of sensor used is not critical to the present invention. Any sensor capable of sensing some physiological parameter relatable to physical activity of a patient can be used. Such sensors are commonly used with rate-responsive implantable medical devices in order to adjust the rate of the implantable medical device in a manner that tracks the physiological needs of the patient. The output of sensor 68 represents an activity level.

[0107] By means of the output signal of activity sensor 68 the control unit 62 is able to assign each intrinsic heart rate to an activity thus enabling collection of intrinsic heart rate value for a patient's state of rest and a patient's state of exercise separately.

[0108] The control unit CTRL 62 is adapted to determine an adequate heart rate or stimulation rate in any manner known as such.

[0109] FIGS. 3A and 3B illustrate that typically the inter-ventricular conduction time from the right ventricle to a particular site in the left ventricle (position of a respective one of a plurality of electrode poles 141, 142, 143 and 144 on the left ventricular electrode lead 114) depends on the origin of the right ventricular activity. FIG. 3A illustrates an example configuration wherein an intrinsic right ventricular event is last sensed by the second (from top) left ventricular electrode pole 143. Alternatively, FIG. 3B provides an example configuration wherein a paced (stimulated) right ventricular event is last sensed by the topmost left ventricular electrode pole 144.

[0110] In FIG. 3A the latest conducted left ventricular event that corresponds to the maximum sensed inter-ventricular propagation delay (RVs to LVs) is marked with L.sub.S(RV.sub.S). In FIG. 3B, the latest conducted left ventricular event in case of a paced right ventricular event (corresponding to maximum paced inter-ventricular propagation delay (RVp to LVs)) is marked with L.sub.S(RV.sub.P). As can be taken from FIGS. 3A and 3B the latest activation sites in the left ventricle are not the same and are based upon the presence or absence of intrinsic right atrial ventricular conduction.

[0111] FIG. 4 discloses inter-ventricular conduction times in case of an intact right-side intrinsic atrioventricular conduction, while FIG. 5 discloses inter-ventricular conduction times in case of a compromised intrinsic right-side atrioventricular conduction. Control unit 62 preferably is adapted to determine the longest inter-ventricular conduction time for each class of right-side conduction status, that is, depending on whether or not intrinsic right atrioventricular conduction is present (as in FIG. 4) or not (as in FIG. 5). Control unit 62 can do so by measuring times t.sub.R1, t.sub.1, t.sub.2, t.sub.3 and t.sub.4 for each class of right-side conduction.

[0112] In the examples given in FIGS. 3A, 3B, 4 and 5, control unit 62 would determine that left ventricular ring electrode 143 would provide the best left ventricular pacing site in case of a presence of intrinsic right atrioventricular conduction, while left ventricular ring electrode 144 would provide the best left ventricular pacing site in case of an absence of intrinsic right atrioventricular conduction.

[0113] The main purpose of the sensing stages 56, 58 and 60 is to detect a natural (intrinsic) contraction of the respective heart chamber in order to generate a sense event signal like an atrial sense event As, a right ventricular sense event RVs and a left ventricular sense event LVs. These sense events are processed by the control unit CTRL 62 in order to inhibit a delivery of a stimulation pulse when the implantable medical device is operating in a demand mode or in order to determine a time interval between an atrial event and a point of time. Another type of event to be processed by the control unit CTRL 62 would be the delivery of a stimulation pulse to a respective heart chamber. Delivery of a stimulation pulse causes a paced event such as an atrial paced event Ap, a right ventricular paced event RVp and a left ventricular paced event LVp.

[0114] According to a preferred embodiment of the present invention, different left ventricular pacing sites are chosen depending on whether control unit 62 receives an RVs signal appropriately coordinated within a preceding Ax and thus detects an intrinsic atrioventricular conduction condition or not. Different pacing sited are established by choosing one (or a sub-set) of left ventricular electrodes 141, 142, 143 or 144 for delivery of left ventricular stimulation pulses.

[0115] Left ventricular pacing is typically deemed optimal when it is administered at the latest activated region within the left ventricle. Determining the latest activated region has historically been assessed only in the context of intrinsic activation without explicit consideration for latest site locations emergent from paced right ventricular activity. In the context of CRT therapies, the patient often witnesses pacing in both ventricles and, as such, targeting the left ventricular pacing site to the latest activated region emergent from right atrioventricular conducted events is likely an inappropriate choice. Such conclusions emerge from the reality that intrinsic right ventricular activity and paced right ventricular activity often change the physical location of the latest activated region within the left ventricle.

[0116] Therefore, control unit 62 is configured for monitoring of right atrioventricular conduction behaviors as a switch for left ventricular pacing vector assignment. In cases where intrinsic right atrioventricular conduction exists, the left ventricular pacing vector should be the one affiliated with the longest intrinsic inter-ventricular (RVs to LVs) conduction path and in cases where intrinsic right atrioventricular A to RV conduction does not exist, the left ventricular pacing vector should be the one affiliated with the longest paced inter-ventricular (RVp to LVs) conduction path.

[0117] Such a capability makes use of a quadri-polar left ventricular electrode lead 114. Such leads provide the implantable medical device 100 with physical means for assessing inter-ventricular (RV to LV) conduction times across a multitude of distinct left ventricular pacing sites and, in turn, provisioning the selection of a pacing vector in accordance with the latest activated region subject to either sensed right ventricular events (RVs) (graded with respect to their coordination with preceding atrial events) or paced right ventricular events (RVp). Pairing such a quadri-polar left ventricular electrode lead 114 with an in-implant algorithm that either continually or periodically monitors right-side atrioventricular conduction would facilitate the ability to use the presence or absence of right atrioventricular conduction as the pacing vector determinant.

[0118] During normal biventricular (BiV) modes, pacing typically occurs in either: 1.) both ventricles (what is referred to as BiV pacing), 2.) only in the left ventricle as an event coordinated with sensed right ventricular activity, or 3.) only in the right ventricle (wherein 2.) and 3.) are referred to as CRT pacing). The feature proposed herein can easily be combined with normal BiV modes through the continual monitoring of right atrioventricular conduction behaviors. Any time a conducted right atrioventricular (A to RVs) event sequence occurs, the left ventricular vector associated with maximum inter-ventricular (RVs to LVs) propagation delays is used and in cases where no conducted event arrived in the right ventricle, the left ventricular vector associated with maximum paced right atrioventricular (RVp to LVs) propagation delays is used. Such an implementation preferably assesses and potentially modifies the left ventricular pacing vector on a beat-by-beat basis. A simplified approach may instead use a periodic RVp suppression survey (a capability we already have in our commercially-available CRT implants, i.e., the inhibition of right ventricular stimulation pulses in a demand mode) to assess for the presence of right-side conducted activity and avoid the continuous overhead associated with monitoring the event sequences on a beat-by-beat basis. In this context, it is noted that there are two periodic options available, one for assessing the right side conduction condition and a second for evaluating the best LV pacing support vector in implementations that provide ambulatory adaptation capabilities.

[0119] In automated modes that determine the appropriate LV pacing sites based on right-side conduction status, a periodic survey of RV to LV conduction values would occur. This capability would amount to an automated, implant-executed LVQC conduction algorithm that actively seeks the longest conduction sites within the LV as is illustrated in FIGS. 4 and 5. Within this routine the implant would be configured to measure the RV to LV conduction times at each pole of the LV pacing lead subject to conditions where right-side conduction prevailed and also subject to conditions where right-side conduction was absent. One could readily envision an elongation of the programmed AV delay facilitating the measurements for cases where right-side conduction prevailed and conversely employing an overdriven RV pacing routine (with shortened AV delays) as a means for collecting intraventricular conduction measurements in the absence of right-side AV conduction. The collected measurements could then be used to determine the appropriate LV pacing vector for each right-side conduction condition. In sophisticated implementations the selection of the LV vector could furthermore be influenced by restrictions imposed by the clinician at follow-up such as those that restricted vector selections that could instate problematic service lifetime implications. In simplified formats, establishing the appropriate LV vector could be limited to test-based data collection efforts coordinated at follow-up. The established vectors could then be held fixed within the implant until changes were made through subsequent follow-up test interactions.

[0120] A further simplification still may embody a method for tying the selection of a left ventricular stimulation electrode pole to mode selection. BiV modes could then employ the pacing site (left ventricular electrode pole selection) associated with paced inter-ventricular (RVp to LVs) maximum propagation delays and all LV-only BiV modes would leverage the pacing site (left ventricular electrode pole selection) associated with intrinsic inter-ventricular (RVs to LVs) maximum propagation delays.

[0121] The best implementation of this invention embodies a continual adaptation of the pacing vector to right-side conduction status on a beat-by-beat basis. Such a strategy ensures that each CRT supported cardiac cycle is paced from an optimal left ventricular site whether the cycle happened to present conducted right ventricular activity or not.

[0122] FIGS. 6A to 6C illustrate the effect of bad or good ventricular coordination, respectively. FIGS. 6A and 6B illustrate cases where the right ventricular and the left ventricular contractions are not well coordinated and thus the septal wall moves away from the central plane in the non-physiologic fashion during ventricular contraction activities. In the example illustrated FIG. 6A the left ventricular contraction occurs too early with respect to the right ventricular contraction, while in the example depicted in FIG. 6B the right ventricular contraction occurs too early with respect to the left ventricular contraction.

[0123] Ideally, the right ventricular and the left ventricular conductions are well coordinated so that the septal wall maintains a fixed, centered position; see FIG. 6C.

[0124] The implantable medical device 100 may further be configured for selective manual enablement or disablement of the automatic left ventricular pacing site selection altogether to thus provide a clinician with the freedom to choose whether or not to administer this adapted pacing site capability at all. Such freedom would afford maximal end-user discretion with regard to this feature's use/implementation. The specific pacing vectors used in each condition can either be clinician determined and selected at follow-up (likely as an offshoot of the LVQC test) or stem from an automated implant-administered survey of inter-ventricular conduction times. In turn, the feature can dynamically update the pacing vector based upon: 1.) need (A to RV conduction present?), and 2.) inter-ventricular conduction times (either Max[RVs to LVs] or Max[RVp to LVs], respectively).

[0125] According to this invention, implantable medical devices offering CRT can dynamically update the pacing site location in response to emergent patient conduction behaviors. Such coordination can occur even in ambulatory conditions outside of clinical settings, in ways that avoid unwanted lag between device output and patient demand. This proposed adaptation of left ventricular pacing site locations additionally facilitates device/patient interactions that better mimic intrinsic, physiological septal wall motions and as such promote opportunities for substrate remodeling beyond what present CRT therapies can provide.

[0126] It will be apparent to those skilled in the art that numerous modifications and variations of the described examples and embodiments are possible in light of the above teachings of the disclosure. The disclosed examples and embodiments are presented for the purpose of illustration only, and other alternate embodiments may include some or all of the features disclosed herein. Therefore, it is the intent to cover all such modifications and alternate embodiments as may come within the true scope of this invention, which is to be given the full breadth thereof. Additionally, the disclosure of a range of values is a disclosure of every numerical value within that range, including the end points.