Source: https://patents.google.com/patent/US7933649?oq=7%2C134%2C016
Timestamp: 2018-03-17 13:52:48
Document Index: 470526805

Matched Legal Cases: ['art 12', 'art 12', 'art 12', 'art.\n3', 'art.\n13', 'art.\n19']

US7933649B1 - Implantable cardiac stimulation device and method for measuring intrinsic activity metrics in multi-site pacing - Google Patents
Implantable cardiac stimulation device and method for measuring intrinsic activity metrics in multi-site pacing
US7933649B1
US7933649B1 US11222722 US22272205A US7933649B1 US 7933649 B1 US7933649 B1 US 7933649B1 US 11222722 US11222722 US 11222722 US 22272205 A US22272205 A US 22272205A US 7933649 B1 US7933649 B1 US 7933649B1
US11222722
Adam F. Atherton
An implantable cardiac stimulation device provides measurement of intrinsic heart activity metrics while sustaining pacing of the heart. The device includes a pulse generator that delivers pacing pulses to a first chamber of corresponding chambers of a heart, and a sensing circuit that senses a conducted evoked response of a second chamber of the corresponding chambers of the heart in response to the pacing pulse to provide an electrical signal representing the conducted evoked response. The device further includes a measuring circuit that measures a metric of the electrical signal to approximate a corresponding metric of an intrinsic electrical feature of the second chamber.
This invention relates generally to a programmable cardiac stimulation device and method for measuring intrinsic activity metrics in multi-site pacing. More specifically the present invention relates to a biventricular stimulation device providing measurement of intrinsic electrical features.
Biatrial pacing has also been suggested to lend in coordinating contractions of the right and left atria. As used herein, the term corresponding chambers is meant to refer to either the right and left atria or the right and left ventricle.
With the ability to pace either or both sets of corresponding heart chambers, it is believed that a wide variety of irregularity of heart rhythms may be most efficiently addressed. For example, in a patient suffering from dilated cardiomyopathy, typically the left ventricle is predominately affected in the earlier stages of the disease. The dilated left ventricle has diminished contractility causing its contraction to be slower and weaker than the still healthy right ventricle. Thus, by selecting the stimulation pathway direction from the left ventricle to the right ventricle, the slower left ventricle contraction is initiated prior to the faster right ventricle contraction, yielding superior synchronization of right ventricle and left ventricle contractions.
Determining intrinsic signal amplitudes is essential for implantable pacemaker and defibrillator devices. Currently, such evaluations generally take the form of manual sense tests performed by an external programmer. Automatic sense tests may also be performed periodically by the device itself. In the future, there will also be a need for automatic sensitivity adjustment, in addition to these measurement tests.
These tests have historically been performed by reducing the pacing rate and waiting for intrinsic activity. However, measurement of intrinsic signal amplitude with traditional methods becomes extremely difficult in patients lacking frequent intrinsic activity. It is even more difficult in patients with a biventricular device typically programmed for triggered continuous pacing. The measurements are often frustrating. More importantly, patients may feel uncomfortable due to long escape intervals. If these measurements are to be made without changing the therapy, then automatic R-wave measurements may be extremely difficult, if not impossible.
As will be seen subsequently, the present invention addresses these and other issues. More particularly, and according to an embodiment of the invention, metrics of intrinsic electrical cardiac activity may be measured without upsetting existing pacing therapy in patients lacking intrinsic activity or when overdrive pacing is recommended.
What is described herein is an implantable cardiac stimulation device comprising a pulse generator that delivers pacing pulses to a first chamber of corresponding chambers of a heart, and a sensing circuit that senses a conducted evoked response of a second chamber of the corresponding chambers of the heart in response to a pacing pulse delivered to the first chamber of the heart to provide an electrical signal representing the conducted evoked response which mimics the intrinsic signal. The device further comprises a measuring circuit that measures a metric of the electrical signal to approximate a corresponding metric of an intrinsic electrical feature of the second chamber.
The pulse generator may be arranged to deliver pacing pulses to a ventricle of the heart. Further, the pulse generator may be arranged to deliver pacing pulses to both of the corresponding chambers in a bi-chamber pacing mode. The corresponding chambers may be the right ventricle and the left ventricle or the right atrium and left atrium.
The intrinsic electrical feature may be an R wave. The metric may be an amplitude of the electrical signal, as for example, the R wave. The amplitude may be a peak amplitude of the electrical signal. The metric may alternatively or additionally be a conduction time from the pacing pulse to a peak amplitude of the electrical signal. The device may further comprise a memory that stores a value of the measured metric.
The pulse generator may be arranged to repeatedly vary one of amplitude and width of the pacing pulses delivered to the first chamber. The measuring circuit may then be arranged to correspondingly repeatedly measure the metric of the electrical signal.
The invention may further provide an implantable cardiac stimulation device comprising a pulse generator that delivers pacing pulses to a first ventricle of a heart, and a sensing circuit that senses a conducted evoked response of a second ventricle of the heart in response to a pacing pulse delivered to the first ventricle of the heart to provide an electrical signal representing the conducted evoked response which mimics the intrinsic signal. The device further comprises a measuring circuit the measures a metric of the electrical signal to approximate a corresponding intrinsic R wave metric of the first ventricle.
The invention further provides a method for use in an implantable cardiac stimulation device for approximating a metric of intrinsic heart activity of a given chamber of a heart. The method comprises delivering pacing pulses to a first chamber of the heart, the first chamber being a corresponding chamber with respect to the given chamber of the heart, sensing a conducted evoked response of the given chamber of the heart in response to a pacing pulse delivered to the first chamber of the heart to provide an electrical signal representing the conducted evoked response which mimics the intrinsic signal, and measuring a metric of the electrical signal to approximate the metric of the intrinsic heart activity of the given chamber.
The stimulation device 10 is also shown in electrical communication with the patient's heart 12 by way of an implantable right ventricular lead 30 having, in this embodiment, a right ventricular tip electrode 32, a right ventricular ring electrode 34, a right ventricular (RV) coil electrode 36, and an SVC coil electrode 38. Typically, the right ventricular lead 30 is transvenously inserted into the heart 12 so as to place the right ventricular tip electrode 32 in the right ventricular apex so that the RV coil electrode will be positioned in the right ventricle and the SVC coil electrode 38 will be positioned in the superior vena cava. Accordingly, the right ventricular lead 30 is capable of receiving cardiac signals, and delivering stimulation in the form of pacing to the right ventricle and shock therapy to the heart.
As illustrated in FIG. 2, a simplified block diagram is shown of the multi-chamber implantable stimulation device 10 according to an embodiment of the present invention, which is capable of treating both fast and slow arrhythmias with stimulation therapy, including cardioversion, defibrillation, and pacing stimulation. While a particular multi-chamber device is shown, this is for illustration purposes only, and one of skill in the art could readily duplicate, eliminate or disable the appropriate circuitry in any desired combination to provide a device capable of treating the appropriate chamber(s) with cardioversion, defibrillation and pacing stimulation.
To achieve left chamber sensing and pacing and shocking delivery with vectors using electrodes in the left heart, the connector includes at least a left ventricular tip terminal (VL TIP) 44, a left atrial ring terminal (AL RING) 46, and a left atrial shocking terminal (AL COIL) 48, which are adapted for connection to the left ventricular ring electrode 26, the left atrial tip electrode 27, and the left atrial coil electrode 28, respectively.
To support right chamber sensing and pacing and shocking delivery with vectors using electrodes in the right heart, the connector further includes a right ventricular tip terminal (VR TIP) 52, a right ventricular ring terminal (VR RING) 54, a right ventricular shocking terminal (RV COIL) 56, and an SVC shocking terminal (SVC COIL) 58, which are adapted for connection to the right ventricular tip electrode 32, right ventricular ring electrode 34, the RV coil electrode 36, and the SVC coil electrode 38, respectively.
Cardiac signals are also applied to the inputs of an analog-to-digital (A/D) data acquisition system 90. The data acquisition system 90 is configured to sense cardiac activity to acquire intracardiac electrogram signals (IEGMs), convert the raw analog data into a digital signal, and store the digital signals for later processing and/or telemetric transmission to an external device 102. The data acquisition system 90 is coupled to the right atrial lead 20, the coronary sinus lead 24, and the right ventricular lead 30 through the switch 74 to sample cardiac signals across any pair of desired electrodes. As will be seen subsequently, the data acquisition system 90 may be coupled to appropriate electrodes and used for sensing a conducted evoked response of a second heart chamber in response to an applied stimulus to a first and corresponding heart chamber. The IEGM thus acquired may then be used for measuring heart activity metrics approximating corresponding metrics of intrinsic activity of the second chamber. The corresponding chamber may be the ventricles, for example, with the first chamber being the left ventricle and the second chamber being the right ventricle. The measured metrics may be, for example, amplitudes, such as peak R wave amplitudes, or time periods, such as conduction times from the applied stimulus, such as a pacing pulse, to the peak R wave amplitude. Still further, stimulation parameters, such stimulation energy or pulse width may be continuously varied and the metrics correspondedly and repeatedly measured to determine the effects resulting from the varied parameters.
With continued reference to FIG. 2, it will be noted that the device 10 further includes a measuring circuit 62 and a morphology detector 64. The morphology detector 64 may be utilized for isolating those features of the IEGM signals having the metric or metrics to be measured. Morphology detectors capable of providing this function are known in the art.
The measuring circuit 62 may, according to this embodiment, measure the metrics of interest. As previously mentioned, the metrics may be, for example, peak R wave amplitudes and conduction times. Other metrics may also be of interest as may be appreciated by those skilled in the art.
The microcontroller 60 is further coupled to a memory 94 by a suitable data/address bus 96, wherein programmable operating parameters used by the microcontroller 60 may be stored and modified, as required, in order to customize the operation of the stimulation device 10 to suit the needs of a particular patient. Such operating parameters define, for example, pacing pulse amplitude, pulse duration, electrode polarity, rate, sensitivity, automatic features, arrhythmia detection criteria, and the amplitude, waveshape and vector of each shocking pulse to be delivered to the patient's heart 12 within each respective tier of therapy. The memory 94 may also be used to temporarily store the conducted evoked response IEGMs and, more permanently, the measured metric values for later analysis and/or use.
According to this embodiment, conducted evoked responses of one chamber (an evoked response resulting from a paced event in the opposite and corresponding chamber) are used to approximate intrinsic activity of the one chamber. Conducted evoked responses of a chamber can represent normal R-waves of that same chamber since it is transmitted through the tissue globally. The resulting conducted evoked response signal should correlate to the intrinsic signal in the ventricle. Hence, the conducted evoked response might also be referred to as the “far-field R-wave that results from a paced event in the opposite chamber”. Traditionally, it is difficult, if not impossible, to use a paced evoked response for measuring the amplitudes of intrinsic activities. That is, there is no basis for the “paced evoked response” to correlate to the intrinsic signal. However, with bi-ventricular/multi-site pacing, when pacing in one ventricle/one-site and sensing in the other ventricle/other-site, the conducted evoked response detected in the opposite non-paced chamber will be at least similar to the intrinsic contraction events of the non-paced chamber (site) and hence may be used to approximate the intrinsic activity of the non-paced chamber (site).
Thus, according to this embodiment, the measurement of a conducted R wave in a heart chamber can be considered equivalent to the measurement of the intrinsic events in that same chamber or site. For example, when pacing in the right ventricle or the left ventricle only (referred to as the ‘paced chamber’) and sensing in the other ventricle (referred to as the ‘sensed chamber’), the conducted evoked response in the sensed chamber can be considered to be equivalent to an R wave in the sensed chamber. Using bi-ventricular pacing system and a method embodying the invention, the clinician may now avoid modifying patient therapy, i.e. changing the pacing rate, changing from atrioventricular to ventricular pacing, etc., for the sole purpose of determining R wave amplitudes. It can provide an opportunity to determine the signal amplitudes even when patients lack any intrinsic activities and have only infrequent pre-mature contractions.
The process of FIG. 3 initiates with an activity block 120. Here, a pacing pulse is applied to one chamber of corresponding chambers. In accordance with this embodiment, the chamber receiving the pacing pulse is the left ventricle. However, as may be appreciated, the chamber receiving the pulse could alternatively be the right ventricle. Furthermore, the present invention is not limited to strictly biventricular pacing. It could, for example, be utilized to advantage in biatrial pacing as well and as may be appreciated by those skilled in the art.
Upon delivery of the pacing pulse to the left ventricle in accordance with activity block 120, the process then immediately advances to activity block 122 wherein the data acquisition system 90 senses cardiac activity in the right ventricle for sensing the conducted evoked response from the pacing pulse delivered to the left ventricle. The data acquisition system 90, upon sensing the conducted evoked response in the right ventricle generates an IEGM signal representing the conducted evoked response and stores the same in memory 94. After the IEGM of the conducted evoked response is stored, the morphology detector 64 and measuring circuit 62 combine to measure a first metric of the conducted evoked response. The first metric may be the peak amplitude of the evoked response, for example. After the first metric is measured in accordance with activity block 124, the process advances to decision block 126 where it is determined if there are other metrics to be measured. If there are, the process then advances to activity block 128 for measuring the next metric of the conducted evoked response. The metric to be measured in accordance with activity block 128 may be, for example, the conduction time from the delivery of the pacing pulse to the left ventricle to the peak amplitude of the conducted evoked response. When all of the metrics are measured, the process then advances to activity block 130 wherein it is determined if the pacing parameters are to be varied. Under some circumstances, it may be desirable to vary the pacing parameters, such as pacing output or pacing pulse width incrementally over a number of cardiac cycles to determine the effect on the measured metrics of the conducted evoked responses. If pacing parameters are to be varied, the process advances to activity block 132 wherein the pacing parameter or parameters are varied and the process then returns to activity block 120 wherein the next pacing pulse is applied to the left ventricle. If there are no pacing parameters to be varied, the process then returns. The metric or metrics, as they are measured, may of course be stored in memory 94 for later analysis and use.
The measured metrics such as evoked response amplitude and conduction time of the conducted evoked response will approximate corresponding metrics of R wave amplitude and conduction time for intrinsic activity of the right ventricle. As a result, intrinsic R wave features may be measured without the need for varying pacing therapy delivered to a patient.
By virtue of the present invention, important information may be gathered which otherwise has not been obtainable. For example, by measuring the peak amplitude of the conducted evoked response, the peak R wave amplitude of the sensing chamber is now known. This can be used in the critical application of discriminating between a normal R wave and a premature ventricular contraction, for example. Such discrimination is particularly important in being able to avoid pacing during a T wave of the heart.
As previously mentioned, the present invention may be extended to the atria as well wherein the corresponding chambers would be the left and right atria. With the present invention extended to the atria, amplitudes of intrinsic atrial activity may be measured to determine atrial sensitivity, for example, in patients with silent sinus node.
While the invention has been described by means of specific embodiments and applications thereof, it is understood that numerous modifications and variations could be made thereto by those skilled in the art without departing from the spirit and scope of the invention. It is therefore to be understood that within the scope of the claims, the invention may be practiced otherwise than as specifically described herein.)
a pulse generator that delivers pacing pulses to a first chamber of corresponding left and right chambers of a heart;
a sensing circuit that senses a conducted evoked response in a second one of the left and right chambers opposite the first chamber in response to a pacing pulse delivered to the first chamber of the heart to provide an electrical signal representing the conducted evoked response; and
a measuring circuit that measures a metric of the electrical signal to approximate a corresponding metric of an intrinsic signal in the second chamber.
2. The device of claim 1, wherein the pulse generator is arranged to deliver pacing pulses to a ventricle of the heart.
3. The device of claim 1, wherein the pulse generator is arranged to deliver pacing pulses to both of the corresponding chambers in a bi-chamber pacing mode.
4. The device of claim 1, wherein the corresponding chambers are a right ventricle and a left ventricle.
5. The device of claim 4, wherein the intrinsic electrical feature is an R wave.
6. The device of claim 1, wherein the metric is an amplitude of the electrical signal.
7. The device of claim 6, wherein the metric is a peak amplitude of the electrical signal.
8. The device of claim 1, wherein the metric is a conduction time from the pacing pulse to a peak amplitude of the electrical signal.
9. The device of claim 1, further comprising a memory that stores a value of the measured metric.
10. The device of claim 1, wherein the pulse generator is arranged to repeatedly vary amplitude and/or width of the pacing pulses delivered to the first chamber and wherein the measuring circuit is arranged to correspondingly repeatedly measure the metric of the electrical signal.
11. An implantable cardiac stimulation device comprising:
a pulse generator that delivers pacing pulses to a first ventricle of a heart;
a sensing circuit that senses a conducted evoked response of a second ventricle of the heart in response to a pacing pulse delivered to the first ventricle of the heart to provide an electrical signal representing the conducted evoked response; and
a measuring circuit that measures a metric of the electrical signal to approximate a corresponding intrinsic R wave metric of the first ventricle.
12. The device of claim 11, wherein the pulse generator is arranged to deliver pacing pulses to a left ventricle of the heart.
13. The device of claim 11, wherein the pulse generator is arranged to deliver pacing pulses to both ventricles of the heart in a bi-ventricular pacing mode.
14. The device of claim 11, wherein the corresponding chambers are a right ventricle and a left ventricle.
15. The device of claim 11, wherein the metric is an amplitude of the electrical signal.
16. The device of claim 11, wherein the metric is a conduction time from the pacing pulse to a peak amplitude of the electrical signal.
17. In an implantable cardiac stimulation device, a method of approximating a metric of intrinsic heart activity, the method comprising:
delivering pacing pulses to a first chamber of the heart, the first chamber being one of a corresponding left or right chamber of the heart;
sensing a conducted evoked response of in a second one of the left or right chambers opposite the first chamber in response to a pacing pulse delivered to the first chamber of the heart to provide an electrical signal representing the conducted evoked response; and
measuring a metric of the electrical signal to approximate the metric of the intrinsic heart activity of the given chamber.
18. The method of claim 17, wherein delivering pacing pulses comprises delivering pacing pulses to a ventricle of the heart.
19. The method of claim 17, wherein measuring a metric comprises measuring an amplitude of the electrical signal.
20. The method of claim 17, wherein measuring a metric comprises measuring a conduction time from the pacing pulse to a peak amplitude of the electrical signal.
US11222722 2005-09-08 2005-09-08 Implantable cardiac stimulation device and method for measuring intrinsic activity metrics in multi-site pacing Active 2027-01-18 US7933649B1 (en)
US11222722 US7933649B1 (en) 2005-09-08 2005-09-08 Implantable cardiac stimulation device and method for measuring intrinsic activity metrics in multi-site pacing
US13049677 US8521279B2 (en) 2005-09-08 2011-03-16 Implantable cardiac stimulation device and method for measuring intrinsic activity metrics in multi-site pacing
US13049677 Continuation US8521279B2 (en) 2005-09-08 2011-03-16 Implantable cardiac stimulation device and method for measuring intrinsic activity metrics in multi-site pacing
US7933649B1 true US7933649B1 (en) 2011-04-26
ID=43880507
US11222722 Active 2027-01-18 US7933649B1 (en) 2005-09-08 2005-09-08 Implantable cardiac stimulation device and method for measuring intrinsic activity metrics in multi-site pacing
US13049677 Active US8521279B2 (en) 2005-09-08 2011-03-16 Implantable cardiac stimulation device and method for measuring intrinsic activity metrics in multi-site pacing
US (2) US7933649B1 (en)
US20140135866A1 (en) * 2011-07-05 2014-05-15 Cardioinsight Technologies, Inc. System and methods to facilitate providing therapy to a patient
US8521279B2 (en) * 2005-09-08 2013-08-27 Pacesetter, Inc. Implantable cardiac stimulation device and method for measuring intrinsic activity metrics in multi-site pacing
US9186515B2 (en) * 2011-07-05 2015-11-17 Cardioinsight Technologies, Inc. System and methods to facilitate providing therapy to a patient
US20110166617A1 (en) 2011-07-07 application
US8521279B2 (en) 2013-08-27 grant
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:ATHERTON, ADAM F.;PEI, XING;SIGNING DATES FROM 20051004 TO 20051005;REEL/FRAME:017131/0081