This document relates generally to medical systems, devices, and methods, and particularly, but not by way of limitation, to a cardiac force sensor and methods of use.
When functioning properly, the human heart maintains a normal sinus rhythm. Its sinoatrial node generates intrinsic electrical cardiac signals that depolarize the atria, causing atrial contractions. Its atrioventricular node then passes the intrinsic cardiac signal to depolarize the ventricles, causing ventricular contractions.
A normal heart is capable of pumping adequate blood throughout the body's circulatory system. However, some people have irregular cardiac rhythms, referred to as cardiac arrhythmias. Moreover, some patients have poor spatial coordination of heart contractions. For these and other reasons, impaired blood circulation may result. For such patients, a cardiac rhythm management (CRM) system may be used to improve the rhythm or spatial coordination of heart contractions. Such systems often include a CRM device that is implanted in the patient to deliver therapy to the heart.
Cardiac rhythm management systems include, among other things, pacemakers, also referred to as pacers. Pacers deliver timed sequences of low energy electrical stimuli, called pacing pulses, to the heart, such as via an intravascular lead wire or catheter (referred to as a “lead”) having one or more electrodes disposed in or about the heart. Heart contractions are initiated in response to such pacing pulses (this is referred to as “capturing” the heart). By properly timing the delivery of pace pulses, the heart can be induced to contract in proper rhythm, greatly improving its efficacy as a pump. Pacers are often used to treat patients with bradyarrhythmias, that is, hearts that beat abnormally slowly. Such pacers may also coordinate atrial and ventricular contractions to improve pumping efficacy.
Cardiac rhythm management systems also include cardiac resynchronization therapy (CRT) devices for spatially coordinating heart depolarizations for improving pumping efficacy. For example, a CRT device may deliver appropriately timed pace pulses to different locations of the same heart chamber to better coordinate the contraction of that heart chamber, or the CRT device may deliver appropriately timed pace pulses to different heart chambers to achieve better synchronization.
Cardiac rhythm management systems also include defibrillators that are capable of delivering higher energy electrical stimuli to the heart. Such defibrillators include cardioverters, which typically synchronize the delivery of such stimuli to sensed intrinsic heart activity signals. Defibrillators are often used to treat patients with tachyarrhythmias, that is, hearts that beat abnormally quickly. Such too-fast heart rhythms can also cause impaired blood circulation. A defibrillator is capable of delivering a high energy electrical stimulus that is sometimes referred to as a defibrillation countershock, also referred to simply as a “shock.” The shock terminates the tachyarrhythmia, allowing the heart to reestablish a normal rhythm for the improved pumping of blood. In addition to pacers, CRT devices, and defibrillators, CRM systems also include CRM devices that combine these functions, as well as monitors, drug delivery devices, and any other implantable or external systems or devices for diagnosing or treating the heart. Cardiac rhythm management systems often include external local or remote user interfaces (sometimes referred to as “programmers” or “patient management systems”) for programming one or more therapy control or other parameters of an implantable cardiac rhythm management device, or for receiving physiological or other data communicated from the implantable cardiac rhythm management device. Accurate measurement of hemodynamic conditions is helpful to developing an effective cardiac rhythm management system.
In the drawings, which are not necessarily drawn to scale, like numerals describe substantially similar components throughout the several views. Like numerals having different letter suffixes represent different instances of substantially similar components. The drawings illustrate generally, by way of example, but not by way of limitation, various embodiments discussed in the present document.
The following detailed description includes references to the accompanying drawings, which form a part of the detailed description. The drawings show, by way of illustration, specific embodiments in which the invention may be practiced. These embodiments, which are also referred to herein as “examples,” are described in enough detail to enable those skilled in the art to practice the invention. The embodiments may be combined, other embodiments may be utilized, or structural, logical and electrical changes may be made without departing from the scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims and their equivalents.
In this document, the terms “a” or “an” are used, as is common in patent documents, to include one or more than one. In this document, the term “or” is used to refer to a nonexclusive or, such that “A or B” includes “A but not B,” “B but not A,” and “A and B,” unless otherwise indicated. Furthermore, all publications, patents, and patent documents referred to in this document are incorporated by reference herein in their entirety, as though individually incorporated by reference. In the event of inconsistent usages between this document and those documents so incorporated by reference, the usage in the incorporated reference(s) should be considered supplementary to that of this document; for irreconcilable inconsistencies, the usage in this document controls.
Sensing electrical cardiac conductions may not provide the desired information about a cardiac contraction. In certain circumstances, it is useful to be able to detect mechanical indications of heart contractions, either in addition to or as an alternative to detecting the electrical cardiac conduction of heart contractions. The present inventors have recognized a need for improved techniques for measuring, monitoring or trending of cardiac conditions, such as by sensing cardiac force.
In the example of
In this example, the force sensor 212 includes a force transducer 210. The force transducer 210 includes a displacement sensor 205 and a spring or other contractile structure that contracts (or expands) in response to an applied force. To convert displacement into force, the contractile structure typically includes a specified linear or non-linear force-displacement relationship, such as a specified spring constant, for example. In the example of
The electronics unit 203 can be configured to determine an indication of cardiac force directly, or as a function of the sensed displacement, such as by using a controller, processor, or other circuit. In a linear displacement sensor example, since the spring constant of the contractile material is known, force can be determined as the multiplicative product of the spring constant and the sensed displacement. The electronics unit 203 can be separate from or integrated with the force sensor 212.
One or more of the leads 301 are adapted to communicate measurements taken by the one or more force sensors 305, and any electrical signals communicated with the one or more electrodes 307. In various examples, the controller 303 is adapted to initiate or adjust one or more responses, such as a delivered electrical energy or a delivered substance, based on one or more sensed forces and/or one or more other physiological parameters. As an example, the controller 303 may cycle through various parameter settings (e.g., electrode selection, pacing location, pacing rate, AV-delay, interventricular delay, intraventricular delay, or the like) to test how strongly the heart contracts in response to a particular combination of parameter settings. The parameter settings corresponding to the desired contraction or contraction pattern can then be selected for ongoing use. Such testing can be carried out recurrently or periodically, such as in case physiological conditions change so that the current parameter settings no longer obtain the desired heart contraction or contraction pattern. If so, the parameter settings can be adjusted as desired. The parameter settings need not be based exclusively on the sensed force; in other examples, the sensed force is just one factor among others in determining the parameter settings.
The force sensor signals can also be processed to determine contraction time, expansion time, a relative figure of merit of the two, or a “pause” time between contraction and expansion. Such information can be used as a patient diagnostic indicator (e.g., by comparison to a threshold value), or to control adjustment of one or more therapy control parameter settings, as discussed above.
A direction or magnitude of an acute or chronic trend in such measurements can also be obtained. Such information can be used as a patient diagnostic indicator (e.g., by comparison to a threshold value), or to control adjustment of one or more therapy control parameter settings, as discussed above.
The force (or derived characteristic) information can also be used in combination with information from an electrogram signal to determine ventricular uptake or relaxation behavior. The electrogram signal includes depolarization information about a ventricular contraction, and repolarization information about a ventricular expansion. For example, a time interval between the onset or peak of the electrogram-indicated ventricular depolarization and the onset or peak of the mechanically-indicated contractive force can provide diagnostic information about the heart contraction. Such information can be used as a patient diagnostic indicator (e.g., by comparison to a threshold value), or to control adjustment of one or more therapy control parameter settings, as discussed above. Similar information can be developed from a time interval between the electrogram-indicated depolarization and the force-indicated ventricular expansion.
For example, a timing between peak contractive forces at such different locations within the same heart chamber can indicate the mechanical contraction delay of that heart chamber at such different locations of that heart chamber. As an illustrative example, a time between peak contractive forces of two right ventricular (RV) force sensors at different RV locations (e.g., RV freewall and RV septum) provides an indication of intraventricular mechanical delay. Another illustrative example includes a left ventricular force sensor (e.g., within a coronary vein) and an RV septum force sensor (e.g., as a proxy, at the common septal wall in RV, for an LV septum force sensor) to provide an indication of intraventricular mechanical delay. Regardless of whether such an intraventricular mechanical delay exists, if a contraction force at a first location of a heart chamber is inappropriate in magnitude or direction relative to a second location of that heart chamber, an intraventricular dyssynchrony exists. Such intraventricular dyssynchrony can be measured using the force sensors at the different locations of the heart chamber, such as by comparing the force at one location to the force at another location, or by computing a ratio, difference, or other relative indication of the forces at the different locations and comparing that relative indication to a certain threshold value. Additionally or alternatively, these examples can provide similar indications for heart chamber expansion forces, rather than heart chamber contractive forces. The measurement of intraventricular delay or intraventricular dyssynchrony can be used to provide a patient diagnostic indicator, or to automatically or otherwise control therapy delivery by the device.
For example, a timing between occurrences of peak contractive forces at different locations in different heart chambers can indicate the mechanical delay of the contraction between heart chambers. As an illustrative example, a time between a peak contractive force of an RV force sensor and a peak contractive force of an LV force sensor will provide an indication of interventricular mechanical delay. Regardless of whether such an interventricular mechanical delay exists, if an RV contraction force is inappropriate in magnitude or direction relative to an LV contraction force, an interventricular dyssynchrony exists. Such interventricular dyssynchrony can be measured using the RV and LV force sensors, such as by comparing the RV and LV forces, or by computing a ratio, difference, or other relative indication of the RV and LV forces and comparing that relative indication to a threshold value. Additionally or alternatively, these examples can provide similar indications for heart chamber expansion forces, rather than heart chamber contractive forces. The measurement of interventricular delay or interventricular dyssynchrony can be used to provide a patient diagnostic indicator, or to automatically or otherwise control therapy delivery by the device.
If the interventricular mechanical delay or interventricular dyssynchrony exists, one or more bi-ventricular pacing or other response parameters (e.g., electrostimulation voltage, electrode selection for electrostimulation, LV offset (timing between LV and RV paces) or the like) may be initiated or adjusted, either automatically or by user-programming.
The interventricular mechanical delay or interventricular dyssynchrony can be measured using the force signals, or one or more characteristics derived from such force signals, such as acceleration, velocity, displacement, or pressure. For example, a time derivative of pressure (DP/DT) can provide an indicator of interventricular dyssynchrony.
Such information can be obtained from an intrinsic heart contraction, or from an evoked response to one or more delivered electrostimulations. In addition or as an alternative to adjusting a cardiac resynchronization parameter, the evoked response information can be used, for example, in an autothreshold or autocapture technique, such as to reduce or adjust electrostimulation energy, such as to promote longevity of the implanted device.
Although the above description has emphasized sensing force, the present force sensor techniques also permit sensing of displacement or motion, which is also useful for the various applications discussed herein.
It is to be understood that the above description is intended to be illustrative, and not restrictive. For example, the above-described embodiments (and/or aspects thereof) may be used in combination with each other. Many other embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope of the invention should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Also, in the following claims, the terms “including” and “comprising” are open-ended, that is, a system, device, article, or process that includes elements in addition to those listed after such a term in a claim are still deemed to fall within the scope of that claim. Moreover, in the following claims, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects.
The Abstract is provided to comply with 37 C.F.R. §1.72(b), which requires that it allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. Also, in the above Detailed Description, various features may be grouped together to streamline the disclosure. This should not be interpreted as intending that an unclaimed disclosed feature is essential to any claim. Rather, inventive subject matter may lie in less than all features of a particular disclosed embodiment. Thus, the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separate embodiment.
This application is a Division of U.S. application Ser. No. 11/559,702, filed on Nov. 14, 2006, now issued as U.S. Pat. No. 7,848,822, the benefit of priority of which is claimed herein, and which is incorporated herein by reference in its entirety.
Number | Name | Date | Kind |
---|---|---|---|
3724274 | Millar | Apr 1973 | A |
3958588 | Huddle | May 1976 | A |
3971364 | Fletcher et al. | Jul 1976 | A |
4979510 | Franz et al. | Dec 1990 | A |
5255679 | Imran | Oct 1993 | A |
5300106 | Dahl et al. | Apr 1994 | A |
5353800 | Pohndorf et al. | Oct 1994 | A |
5405337 | Maynard | Apr 1995 | A |
5423883 | Helland | Jun 1995 | A |
5496361 | Moberg et al. | Mar 1996 | A |
5589563 | Ward et al. | Dec 1996 | A |
5607996 | Nichols et al. | Mar 1997 | A |
5628777 | Moberg et al. | May 1997 | A |
5683447 | Bush et al. | Nov 1997 | A |
5693081 | Fain et al. | Dec 1997 | A |
5782841 | Ritz et al. | Jul 1998 | A |
5800497 | Bakels et al. | Sep 1998 | A |
5843153 | Johnston et al. | Dec 1998 | A |
5938603 | Ponzi | Aug 1999 | A |
5991661 | Park et al. | Nov 1999 | A |
6205359 | Boveja | Mar 2001 | B1 |
6215231 | Newnham et al. | Apr 2001 | B1 |
6254568 | Ponzi | Jul 2001 | B1 |
6301507 | Bakels et al. | Oct 2001 | B1 |
6324414 | Gibbons et al. | Nov 2001 | B1 |
6327492 | Lemelson | Dec 2001 | B1 |
6332089 | Acker et al. | Dec 2001 | B1 |
6340588 | Nova et al. | Jan 2002 | B1 |
6514237 | Maseda | Feb 2003 | B1 |
6522909 | Garibaldi et al. | Feb 2003 | B1 |
6699186 | Wolinsky et al. | Mar 2004 | B1 |
6809462 | Pelrine et al. | Oct 2004 | B2 |
6871088 | Chinchoy | Mar 2005 | B2 |
6881516 | Aamodt et al. | Apr 2005 | B2 |
6915162 | Noren et al. | Jul 2005 | B2 |
6939313 | Saadat et al. | Sep 2005 | B2 |
6980866 | Yu et al. | Dec 2005 | B2 |
7072703 | Zhang et al. | Jul 2006 | B2 |
7203541 | Sowelam et al. | Apr 2007 | B2 |
20020111662 | Iaizzo et al. | Aug 2002 | A1 |
20020116043 | Garibaldi et al. | Aug 2002 | A1 |
20030055360 | Zeleznik | Mar 2003 | A1 |
20030065373 | Lovett et al. | Apr 2003 | A1 |
20030139794 | Jenney et al. | Jul 2003 | A1 |
20040049255 | Jain et al. | Mar 2004 | A1 |
20040127889 | Zhang et al. | Jul 2004 | A1 |
20040225332 | Gebhardt et al. | Nov 2004 | A1 |
20050240233 | Lippert et al. | Oct 2005 | A1 |
20050288727 | Penner | Dec 2005 | A1 |
20060041298 | Yu et al. | Feb 2006 | A1 |
20060178586 | Dobak, III | Aug 2006 | A1 |
20080114256 | Zhang et al. | May 2008 | A1 |
20080255629 | Jenson et al. | Oct 2008 | A1 |
20080262473 | Kornblau et al. | Oct 2008 | A1 |
Number | Date | Country |
---|---|---|
WO-9502359 | Jan 1995 | WO |
WO-9503086 | Feb 1995 | WO |
WO-9503086 | Feb 1995 | WO |
WO-2005011803 | Feb 2005 | WO |
WO-2005118056 | Dec 2005 | WO |
WO-2005118056 | Dec 2005 | WO |
Entry |
---|
“U.S. Appl. No. 11/559,702, Final Office Action mailed Apr. 16, 2010”, 15 pgs. |
“U.S. Appl. No. 11/559,702, Non-Final Office Action mailed Nov. 9, 2009”, 15 pgs. |
“U.S. Appl. No. 11/559,702, Notice of Allowance mailed Jul. 30, 2010”, 8 pgs. |
“U.S. Appl. No. 11/559,702, Response filed Feb. 9, 2010 to Non Final Office Action mailed Nov. 9, 2009”, 15 pgs. |
“U.S. Appl. No. 11/559,702, Response filed Jul. 15, 2010 to Final Office Action mailed Apr. 16, 2010”, 15 pgs. |
“U.S. Appl. No. 11/559,702, Response filed Sep. 1, 2009 to Restriction Required mailed Aug. 13, 2009”, 10 pgs. |
“U.S. Appl. No. 11/559,702, Restriction Requirement mailed Aug. 13, 2009”, 7 pgs. |
“U.S. Appl. No. 11/559,702, Supplemental Notice of Allowability Mailed Oct. 14, 2010”, 5 pgs. |
Bennett, T., et al., “Development of implantable devices for continuous ambulatory monitoring of central hemodynamic values in heart failure patients”, Pacing Clin Electrophysiol, vol. 28, No. 6, (Jun. 2005), 573-584. |
Bongiorni, M. G, et al., “Is local myocardial contractility related to endocardial acceleration signals detected by a transvenous pacing lead?”, Pacing Clin Electrophysiol, (11 Pt 2), (Nov. 1996), 1682-1688. |
Measurand Inc., “S700 & S710 Joint Angle ShapeSensor Spec Sheet, S720 Miniature Joint Angle Shape Sensor, S290 12 Bit Data Acquisition System”, www.measurand.com/products/shapesensors-literature.html, (Sep. 12, 2002), 5 pgs. |
Measurand Inc., “ShapeRecorder Software User Instructions”, www.measurand.com, (2002), 66 pgs. |
Measurand Inc., “ShapeTape Manual”, Cautions, Description of Hardware and software options, Description and use of hardware, Instructions for ShapeWare software, Theory, (Aug. 15, 2003), i/143-114/143, I-XIX. |
SRI International, “Research of Artificial Muscles”, www.mmc.or.jp/info/magazine/14e/act/11/sri1.htm, (Mar. 1996), 6 pgs. |
Theres, Heinz P, et al., “Detection of acute myocardial ischemia during percutaneous transluminal coronary angioplasty by endocardial acceleration.”, Pacing Clin Electrophysiol., vol. 27, No. 5, (May 2004), 621-625. |
www.designinsite.dk, “Material Dielectric Eastomers”, web.archive.org/web/20010306073022/www.designinsite.dk/htmsider/insptour.htm, Copyright 1996-2003 Torben Lenau. This page is part of Design inSite, (Copyright 1996-2003), 2 pgs. |
Number | Date | Country | |
---|---|---|---|
20110046496 A1 | Feb 2011 | US |
Number | Date | Country | |
---|---|---|---|
Parent | 11559702 | Nov 2006 | US |
Child | 12940172 | US |