Source: http://www.google.com/patents/US20080249583?dq=5754119
Timestamp: 2015-03-30 14:02:43
Document Index: 294152996

Matched Legal Cases: ['art.\n7', 'art.\n8', 'art 105', 'art 105', 'art 105', 'art 105', 'art 615', 'art 615', 'art 615']

Patent US20080249583 - Therapy control based on the rate of change of intracardiac impedance - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inAdvanced Patent SearchPatentsA system comprising a medical device that includes an impedance measurement circuit adapted to be coupled to implantable electrodes to obtain an intracardiac impedance signal between electrodes, a therapy circuit operable to deliver a therapy to a subject, and a controller circuit coupled to the impedance...http://www.google.com/patents/US20080249583?utm_source=gb-gplus-sharePatent US20080249583 - Therapy control based on the rate of change of intracardiac impedanceAdvanced Patent SearchPublication numberUS20080249583 A1Publication typeApplicationApplication numberUS 12/105,219Publication dateOct 9, 2008Filing dateApr 17, 2008Priority dateJun 29, 2005Also published asUS7376463, US7953485, US20070005114Publication number105219, 12105219, US 2008/0249583 A1, US 2008/249583 A1, US 20080249583 A1, US 20080249583A1, US 2008249583 A1, US 2008249583A1, US-A1-20080249583, US-A1-2008249583, US2008/0249583A1, US2008/249583A1, US20080249583 A1, US20080249583A1, US2008249583 A1, US2008249583A1InventorsRodney W. Salo, Joseph M. Pastore, Jeffrey E. Stahmann, Jesse W. HartleyOriginal AssigneeCardiac Pacemakers, Inc..Export CitationBiBTeX, EndNote, RefManReferenced by (8), Classifications (6), Legal Events (1) External Links: USPTO, USPTO Assignment, EspacenetTherapy control based on the rate of change of intracardiac impedance
US 20080249583 A1Abstract
an impedance measurement circuit adapted to be communicatively coupled to implantable electrodes to provide an intracardiac impedance signal between electrodes; a therapy circuit configured to deliver pacing therapy to a right ventricle and a left ventricle of a subject; and a controller circuit communicatively coupled to the impedance measurement circuit and the therapy circuit, wherein the controller circuit is configured to determine a time rate of change of the intracardiac impedance signal, and to adjust a time delay between pacing of the right ventricle and pacing of the left ventricle in order to controllably increase or maximize a magnitude of the time rate of change in a closed feedback loop manner. 2. The system of claim 1, wherein the controller circuit is configured to adjust the time delay between pacing of the right and left ventricles in order to controllably increase or maximize a magnitude of the negative time rate of change in a closed feedback loop manner.
3. The system of claim 1, wherein the controller circuit is configured to adjust the time delay between pacing of the right and left ventricles in order to controllably increase or maximize both a magnitude of the negative time rate of change and a magnitude of the positive time rate of change in a closed feedback loop manner.
4. The system of claim 1, wherein the impedance measurement circuit is adapted to be communicatively coupled to:
a first set of electrodes adapted for placement to correspond to a first impedance vector at a first site of a heart of a subject; and a second set of electrodes adapted for placement to correspond to a different second impedance vector at a second site of the heart, wherein the impedance circuit is configured to provide a first intracardiac impedance signal from the first set of electrodes and a second intracardiac impedance signal from the second set of electrodes, and wherein the controller circuit is configured to:
determine a time rate of change of the first and second intracardiac impedance signals; and
adjust a time delay between pacing of the right and left ventricles in a closed loop feedback arrangement to controllably increase or maximize a magnitude of the time rate of change of both the first and second intracardiac impedance signals.
5. The system of claim 4, wherein the controller circuit is configured to controllably increase or maximize both a positive and a negative magnitude value of the time rate of change of the first and second intracardiac impedance signals.
6. The system of claim 4, wherein the first set of electrodes is adapted for placement in or near a left ventricle of the heart and the second set of electrodes is adapted for placement in a right ventricle of the heart.
7. The system of claim 4, wherein the first set of electrodes adapted for placement in a right atrium of the heart and the second set of electrodes is adapted for placement in a right ventricle of the heart.
8. The system of claim 4, wherein the controller circuit is configured to give more weight to increasing or maximizing the magnitude of the time rate of change of the first intracardiac impedance signal than to increasing or maximizing the time rate of change of the second intracardiac impedance signal.
9. A system comprising a medical device including:
an impedance measurement circuit adapted to be coupled to implantable electrodes to obtain an intracardiac impedance signal between electrodes; a therapy circuit configured to deliver pacing therapy to a subject; and a controller circuit communicatively coupled to the impedance measurement circuit and the therapy circuit, wherein the controller circuit is configured to:
determine a time rate of change of the intracardiac impedance signal;
derive a time duration from a cardiac event to a time of peak wall thickness for a ventricle free wall using the time rate of change of the intracardiac impedance signal; and
adjust a therapy parameter provided to the patient to controllably adjust the time duration in a closed feedback loop manner.
10. The system of claim 9, wherein the cardiac event includes an atrial depolarization.
11. The system of claim 9, wherein the implantable electrodes are adapted for placement in a coronary vein, and wherein controller circuit is configured to determine an occurrence of peak wall thickness of the left ventricle.
12. The system of claim 9, wherein the implantable electrodes are adapted for placement in a left anterior descending artery, and wherein controller circuit is configured to determine an occurrence of peak wall thickness of the left ventricle.
13. The system of claim 9, wherein the therapy circuit is configured to deliver pacing therapy to a right ventricle and a left ventricle of a subject; and
wherein the controller circuit is configured to adjust a time delay between pacing of the right and left ventricles in order to controllably adjust the time duration. 14. The system of claim 9, wherein the therapy circuit is configured to deliver pacing therapy to an atrium and a left ventricle of a subject; and
wherein the controller circuit is configured to adjust a time delay between pacing of the atrium and the left ventricle in order to controllably adjust the time duration from the cardiac event to the time of peak wall thickness. 15. A system comprising a medical device including:
an impedance measurement circuit adapted to be communicatively coupled to a first set of electrodes adapted for placement to correspond to a first impedance vector at a first site of a heart of a subject, and a second set of electrodes adapted for placement to correspond to a different second impedance vector at a second site of the heart, wherein the impedance circuit is configured to provide a first intracardiac impedance signal from the first set of electrodes and a second intracardiac impedance signal from the second set of electrodes; a therapy circuit configured to deliver pacing therapy to a right ventricle and a left ventricle of a subject; and a controller circuit communicatively coupled to the impedance measurement circuit and the therapy circuit, wherein the controller circuit is configured to: derive a time to a peak value of the rate of change of the first intracardiac impedance signal and a time to a peak value of the rate of change of the second intracardiac impedance signal, and adjust a time delay between pacing of the right and left ventricles in a closed loop feedback arrangement to controllably decrease or minimize a difference in the time to peak values. 16. The system of claim 15, wherein the controller circuit is configured to measure the time to peak values relative to a sensed atrial depolarization.
17. The system of claim 15, wherein the controller circuit is configured to determine a peak value using the peak-to-peak value of a time rate change of an intracardiac impedance value.
18. The system of claim 15, wherein the controller circuit is configured to determine a peak value using the baseline-to-peak value of a time rate change of an intracardiac impedance value.
19. The system of claim 15, wherein the first set of implantable electrodes includes an electrode adapted for placement in a right ventricle, and the second set of implantable electrodes include an electrode adapted for placement in a coronary vein.
20. The system of claim 15, wherein the first set of implantable electrodes include an electrode adapted for placement in a right ventricle and the second set of implantable electrodes include an electrode adapted for placement in a left anterior descending artery. Description
This application is a Continuation of U.S. application Ser. No. 11/169,339, filed on Jun. 29, 2005, which is incorporated herein by reference.
Cardiac lead 108 includes a proximal end that is coupled to MD 110 and a distal end, coupled by an electrode or electrodes to one or more portions of a heart 105. The electrodes typically deliver cardioversion, defibrillation, pacing, or resynchronization therapy, or combinations thereof to at least one chamber of the heart 105. The electronics unit of the IMD 110 typically includes components that are enclosed in a hermetically-sealed canister or �can.� Other electrodes may be located on the can, or on an insulating header extending from the can, or on other portions of IMD 110, such as for providing pacing energy, defibrillation energy, or both, in conjunction with the electrodes disposed on or around a heart 105. The lead 108 or leads and electrodes may also typically be used for sensing electrical activity of the heart 105.
The peak positive amplitude of the derivative, or the peak value of the rate of change, is labeled �B.� The peak negative amplitude of the derivative is labeed �C.�
According to some examples, cardiac electrodes placed in or around the heart (e.g., the right ventricle) and an electrode on the IMD (e.g., the IMED �can� electrode) are used to measure impedance. The impedance measurement circuit 310 measures the intrathoracic impedance of the heart and lungs between the cardiac electrodes and the IMD electrode. Impedance measurement circuit 310 includes a filter circuit to remove any pulmonary component of the measurement while retaining the cardiac component of the measurement.
An example of a lead configuration 500 used with the system 300 to monitor intracardiac impedance in both ventricles is shown on FIG. 5. A first cardiac lead 510 is placed in the right atrium 505A and right ventricle 505B. The first cardiac lead includes tip electrode 515, ring electrodes 520 and 525, and atrium electrode 530. A second cardiac lead 535 is placed through the coronary sinus and into a coronary vein. The second cardiac lead 535 includes proximal ring electrode 540 and distal ring electrode 545. In some examples, the second cardiac lead is disposed via the thorax to the epicardium.
In some examples, the system 300 is able to monitor synchrony between the ventricles. A first impedance vector is between a ring electrode 520 placed in the right ventricle 505B and a ring electrode 545 placed in the coronary vein and is sensed with sense amplifier 555. The second impedance vector is between the tip electrode 515 placed in the apex of the right ventricle 505B and between the electrode 525 placed in the base of the right ventricle 505B and is sensed with sense amplifier 550. Alternatively, the first impedance vector is between the electrodes 525 and 545 and the second impedance vector is between right ventricle electrodes 515 and 525. The excitation current can be applied using the same electrodes or different electrodes such as ring electrode 520 and tip electrode 530. The controller circuit 320 of FIG. 3 uses the time to peak rate of change of the impedance vectors to determine synchrony between the left ventricle and the right ventricle. The time is measured from occurrence of a cardiac event such as, for example, from a sensed P-wave. In one example, the controller circuit 320 improves or optimizes the ventricle synchrony, as part of resynchronization therapy, by adjusting pacing times of each ventricle (i.e., interventricular pacing delay offset) to decrease or minimize the difference in time between the signals reaching their peak rate of change value. In another example, the controller circuit 320 optimizes synchrony by maximizing both positive and negative peak values of rate of change.
FIG. 6 is an illustration of portions of another example of a system 600 to control cardiac therapy using sensed intracardiac impedance. In this example, the system 600 includes an IMD 605 that is a cardiac rhythm management device. The IMD 605 is coupled to heart 615 by cardiac leads 610 that include lead tip and ring electrodes 620, 622, 625, 627. The cardiac leads 610 are connected to the IMD at header 640. The IMD 605 includes components that are enclosed in a hermetically-sealed canister or �can� 630. A therapy circuit 670 is used to provide cardiac function management therapy such as pacing and/or defibrillation energy in conjunction with the electrodes disposed in or around heart 615. The leads 610 and lead electrodes 620, 622, 625, 627 are used in conjunction with sense amplifiers 675 for sensing electrical activity of a heart 615.
In some examples, the EMD 605 further includes a memory circuit coupled to the controller circuit 665 for storing trends in measured peak values of rates of change of an intracardiac impedance signal. According to some examples, the system 600 further includes an external device 690 operable to communicate with the IMD 605 using the communication circuit 685. The communication is through wireless signals such as telemetry signals or RF signals. In some examples, the external device 690 is part of, or in communication with, a computer network such as a hospital computer network or the internet. The IMI 605 communicates wirelessly with the external device 690 and the IMD 605 communicates the trend data to the external device 690. In some examples, the external device 690 includes a display to display the trend data.
Referenced byCiting PatentFiling datePublication dateApplicantTitleUS7702389 *Nov 14, 2006Apr 20, 2010Biotronik Crm Patent AgCardiac pacemakerUS8050760 *Nov 13, 2008Nov 1, 2011Pacesetter, Inc.System and method for evaluating mechanical cardiac dyssynchrony based on multiple impedance vectors using an implantable medical deviceUS8639328 *Oct 29, 2010Jan 28, 2014Medtronic, Inc.Cardiac therapy based upon impedance signalsUS8750981Aug 25, 2011Jun 10, 2014Pacesetter, Inc.Systems and methods for assessing heart failure and controlling cardiac resynchronization therapy using hybrid impedance measurement configurationsUS8868184Sep 2, 2011Oct 21, 2014Pacesetter, Inc.System and method for evaluating mechanical cardiac dyssynchrony based on multiple impedance vectors using an implantable medical deviceUS8868185 *Nov 27, 2012Oct 21, 2014Medtronic, Inc.Use of thoracic and extra-thoracic impedance for diagnostic monitoringUS20120109245 *Oct 29, 2010May 3, 2012Hettrick Douglas ACardiac therapy based upon impedance signalsWO2010071488A1 *Dec 17, 2008Jun 24, 2010St. Jude Medical AbImplantable medical device and method for monitoring synchronicity of the ventricles of a heart* Cited by examinerClassifications U.S. Classification607/11, 607/17International ClassificationA61N1/368Cooperative ClassificationA61N1/30, A61N1/36521European ClassificationA61N1/365B2Legal EventsDateCodeEventDescriptionOct 29, 2014FPAYFee paymentYear of fee payment: 4RotateOriginal ImageGoogle Home - Sitemap - USPTO Bulk Downloads - Privacy Policy - Terms of Service - About Google Patents - Send FeedbackData provided by IFI CLAIMS Patent Services