U.S. patent application number 11/386294 was filed with the patent office on 2006-07-20 for vibrational therapy device used for resynchronization pacing in a treatment for heart failure.
This patent application is currently assigned to EBR Systems, Inc.. Invention is credited to Axel F. Brisken, Mark W. Cowan, Debra S. Echt, Richard E. Riley.
Application Number | 20060161061 11/386294 |
Document ID | / |
Family ID | 34657262 |
Filed Date | 2006-07-20 |
United States Patent
Application |
20060161061 |
Kind Code |
A1 |
Echt; Debra S. ; et
al. |
July 20, 2006 |
Vibrational therapy device used for resynchronization pacing in a
treatment for heart failure
Abstract
Systems for pacing the heart include a vibrational transducer
which directs energy at the heart, usually at at least a ventricle,
to pace the heart and to promote synchronized contraction of the
ventricles. Optionally, additional vibrational and/or electrical
stimulation may be provided. The vibrational transducers are
usually implantable at a location proximate the heart.
Inventors: |
Echt; Debra S.; (Woodside,
CA) ; Brisken; Axel F.; (Fremont, CA) ; Riley;
Richard E.; (Palo Alto, CA) ; Cowan; Mark W.;
(Fremont, CA) |
Correspondence
Address: |
TOWNSEND AND TOWNSEND AND CREW, LLP
TWO EMBARCADERO CENTER
EIGHTH FLOOR
SAN FRANCISCO
CA
94111-3834
US
|
Assignee: |
EBR Systems, Inc.
Sunnyvale
CA
|
Family ID: |
34657262 |
Appl. No.: |
11/386294 |
Filed: |
March 21, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10869705 |
Jun 15, 2004 |
7050849 |
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11386294 |
Mar 21, 2006 |
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60528940 |
Dec 10, 2003 |
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60518138 |
Nov 6, 2003 |
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Current U.S.
Class: |
600/439 ;
607/9 |
Current CPC
Class: |
A61N 1/3629 20170801;
A61H 31/006 20130101 |
Class at
Publication: |
600/439 ;
607/009 |
International
Class: |
A61B 8/00 20060101
A61B008/00 |
Claims
1. A method for pacing the heart, the method comprising directing
vibrational pacing energy to at least a portion of ventricular
tissue of the heart, wherein the vibrational energy stimulates
contraction of at least one ventricle.
2. A method as in claim 1, wherein the vibrational energy is
selectively directed at left ventricular tissue.
3. A method as in claim 1, wherein the vibrational energy is
selectively directed at right ventricular tissue.
4. A method as in claim 1, wherein the vibrational energy is
directed at both left and right ventricular tissues.
5. A method as in any one of claims 1 to 4, wherein the vibrational
pacing energy is directed as one or more narrow beams.
6. A method as in any one of claims 1 to 4, wherein the vibrational
pacing energy is directed as one or more wide beams.
7. A method in any one of claims 1 to 4, wherein the vibrational
pacing energy is directed as any combination of one or more narrow
or wide beams.
8. A method as in any one of claims 1 to 4, wherein the vibrational
pacing energy is delivered from a single implanted enclosure.
9. A method as in any one of claims 1 to 4, wherein the vibrational
pacing energy is delivered from two or more implanted
enclosures.
10. A method as in any one of claims 1 to 4, wherein the
vibrational pacing energy is delivered from an external vibrational
transducer.
11. A method as in any one of claims 1 to 4, further comprising
programming delivery of the vibrational energy to promote
synchronized contraction of the left and right ventricles.
12. A method as in any one of claims 1 to 4, further comprising
electrically stimulating one or more regions of the heart in a
coordinated pattern with the delivery of the vibrational pacing
energy.
13. A method as in any one of claims 1 to 4, further comprising
detecting the presence or absence of cardiac signals originating in
the ventricles or atria of the heart and triggering or inhibiting
the delivery of electrical or vibrational energy based on
programmed parameters.
14. A pacing system comprising: an implantable enclosure having
circuitry for controlling a vibrational transducer under conditions
selected to stimulate heart contraction when directed at cardiac
tissue.
15. A pacing system as in claim 14, wherein the circuitry comprises
a power amplifier, an impedance matching circuit, and a signal
generator for controlling the vibrational transducer.
16. A pacing system as in claim 15, further comprising circuitry
for generating electrical pulse(s) for stimulating heart
contraction and circuitry for detection of intrinsic cardiac
signals.
17. A pacing system as in claim 16, further comprising circuitry
which analyzes detected intrinsic heart signals and which controls
the electrical pulses and vibrational pacing to synchronize
contraction of the left and right ventricles.
18. A pacing system as in claim 17, wherein the electrical pulse
circuitry and detection circuitry is located in the same enclosure
as the vibrational transducer circuitry.
19. A pacing system as in claim 14, wherein the vibrational
transducer is located within the enclosure.
20. A pacing system as in claim 14, wherein the vibrational
transducer is connected to the enclosure by a cable.
21. A pacing system as in claim 14, wherein one or more vibrational
transducers are located on a lead and positioned in the right
ventricle.
22. A pacing system as in claim 14, wherein one or more transducers
are located on a lead and positioned in a subcutaneous
location.
23. A pacing system as in claim 14, wherein one or more transducers
are located on a lead and positioned in the right atrium.
24. A pacing system as in claim 14, wherein a vibrational
transducer is directed to ventricular tissue.
25. A pacing systems as in claim 14, wherein a vibrational
transducer is directed to atrial tissue.
26. A pacing system as in claim 14, wherein a vibrational
transducer is directed to both atrial and ventricular tissue.
27. A system as in claim 14, wherein the enclosure is adapted to
include a cardioverter defibrillator.
28. A system as in claim 27, wherein the cardioverter defibrillator
uses electrical energy.
29. A system as in claim 27, wherein the cardioverter defibrillator
uses vibrational energy.
30. A pacing system comprising: a vibrational transducer; and
control circuitry for activating the vibrational transducer in
order to deliver controlled vibrational energy to a target region
of the heart under conditions selected to promote synchronized
contraction of the ventricles.
31. A pacing system as in claim 30, wherein the vibrational
transducer is adapted to contact an exterior surface of the
patient's skin and deliver the vibrational energy through the
tissue overlying the target region of the heart.
32. A pacing system as in claim 31, wherein the control circuitry
comprises a power amplifier, an impedance matching circuit, and a
signal generator for activating the vibrational transducer.
33. A pacing system as in claim 32, further comprising control
circuitry which analyzes detected intrinsic heart signals and which
controls the vibrational energy to promote synchronized contraction
of the ventricles.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] The present application is a divisional of U.S. patent
application Ser. No. 10/869,705 (Attorney Docket No.
021834-000620US), filed Jun. 15, 2004, which claimed priority from
U.S. Patent Application Ser. No. 60/518,138 (Attorney Docket No.
021834-000600US), filed Nov. 6, 2003; and U.S. Patent Application
Ser. No. 60/528,940 (Attorney Docket No. 021834-000610US), filed
Dec. 10, 2003, the full disclosures of which are incorporated
herein by reference.
[0002] The disclosure of the present application is also related to
the following applications being filed on the same day as the
present application: U.S. patent application Ser. No. 10/869,776
(Attorney Docket No. 021834-000130US); filed Jun. 15, 2004 (now
U.S. Pat. No. 7,006,864); U.S. patent application Ser. No.
10/869,242 (Attorney Docket No. 021834-000210US), filed Jun. 15,
2004; and U.S. patent application Ser. No. 10/869,631 (Attorney
Docket No. 021834-000310US), filed Jun. 15, 2004, the full
disclosures of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0003] 1. Field of the Invention
[0004] The systems and methods of this invention relate to pacing
treatment of the heart comprising applying vibrational energy.
[0005] Heart Failure (HF) currently affects over 5 million patients
in the United States alone. This population has been steadily
increasing due to overall demographic aging and, in particular, the
effects of new life-prolonging treatments to patients with chronic
cardiac conditions. HF is defined by ACC/AHA Task force as a
complex clinical syndrome that impairs the ability of the ventricle
to fill with or eject blood. New medications developed to treat HF
have been generally ineffective, and device-based solutions appear
to present a significant opportunity for afflicted patients.
[0006] HF generally results from one or more underlying factors
including hypertension, diabetes, valvular disease, cardiomyopathy,
coronary artery disease, or structural changes to the heart muscle.
HF is characterized by reduced ventricular wall motion in systole
and/or diastole, and low ejection fraction. As the heart becomes
less able to pump sufficient volume to the system, patients develop
symptoms of fluid retention, shortness of breath, and fatigue.
[0007] Approximately one third of patients with HF have poor timing
of contraction between the right and the left ventricle and within
the left ventricle, called interventricular and intraventricular
dyssynchrony, respectively. This is sometimes also manifest by a
wider than normal QRS interval on a surface electrocardiogram (ECG)
taken of a HF patient. The wider than normal QRS interval is called
conduction delay because there is a prolonged time interval for the
normal electrical impulse to travel ("conduct") to all parts of
both ventricles. This is also sometimes manifest by conduction
delay between the atria and ventricles (A-V delay). Ventricular
dyssynchrony and conduction delays can contribute to weak left
ventricular function by causing delayed and/or abnormal left
ventricular contraction. There may be inadequate filling and
emptying of the left ventricle, as well as backflow of blood into
the left atrium, resulting in decreased cardiac output and
increased symptoms for the patient. This dysfunction causes
increased mortality and morbidity among patients with HF.
[0008] Cardiac resynchronization therapy is the use of pacing to
coordinate the contraction of the ventricles in order to reduce
heart failure and improve prognosis in HF patients. Recently,
devices that pace both ventricles, referred to as bi-ventricular
pacing, have been adopted to provide cardiac resynchronization
therapy. A bi-ventricular pacing system utilizes conventional dual
chamber, right atrium and right ventricle, pacing technology but
adds a third lead, usually in a coronary vein, to sense and pace
the epicardial surface of the left ventricle. The pacing device can
then, at an appropriate time interval after right atrial activity,
synchronize contraction of both right and left ventricles either
simultaneously or at coordinated time intervals. The synchronous
contraction of the ventricles facilitates more adequate filling of
the left ventricle and less backflow (mitral valve regurgitation to
the left atrium), resulting in more oxygenated blood being pumped
to the body. Alternatively, it has been shown that pacing only the
left ventricle at a location near the apex is associated with
improvement in left ventricular function. However, this location is
not accessible from the coronary veins in current pacing
systems.
[0009] Clinical studies have shown a sustained improvement of
symptoms and exercise tolerance in patients using bi-ventricular
pacing devices to improve left ventricular function. Cardiac
resynchronization therapy has also been incorporated into
implantable cardioverter defibrillator (ICD) devices, allowing for
the simultaneous treatment of heart failure and the prevention of
sudden cardiac death caused by life-threatening ventricular
arrhythmias in HF patients.
[0010] Pacemaker leads are typically placed through the skin into a
subclavian vein to access the venous side of the cardiovascular
system. In bi-ventricular pacing systems, one lead is placed in
contact with the right ventricular wall and one lead is placed in
contact with the right atrial wall. To access the left ventricle,
the third lead is passed into the right atrium, into the orifice of
the coronary sinus, and then maneuvered through the coronary veins
to a position on the epicardial aspect of the lateral wall of the
left ventricle. Some work has been done exploring minimally
invasive methods of alternatively placing the lead/electrode
directly on the epicardium of the left ventricle.
[0011] Placement of the third lead to contact the left ventricle
has been a significant problem for application of this therapy. The
coronary sinus is a complicated venous pathway with multiple
branches which bend and narrow with considerable variation as they
extend distally onto the epicardium of the left ventricle.
Placement of this lead requires significant skill on the part of
the physician. In order to provide adequate steerability and
pushability, the design of the left ventricular lead or a lead
introduction system/device is much more complicated than for
regular pacing leads. Often the left ventricular lead
positioning/placement can take over an hour to perform exposing the
patient to increased fluoroscopy radiation and increased procedure
risks. Furthermore, in some patients (7.5% in the MIRACLE study),
an acceptable lead placement is not possible due to anatomic
constraints or undesirable phrenic nerve pacing. Additionally, lead
dislodgement and loss of pacing capture have been a common
complication in the use of these coronary sinus leads (e.g., 10-20%
complication rates have been reported within the first 6 months of
device placement).
[0012] It would be beneficial to eliminate the third pacing lead
and yet provide resynchronization within the left ventricle and/or
between the left and right ventricles. Moreover, it would be
beneficial to provide more physiological pacing of the right
ventricle. In normal physiology, the right ventricle is first
stimulated in the upper septal area, and then the impulse travels
down specially conducting pathways to the right ventricular apex.
However, pacing from the right ventricle is virtually always
accomplished from a lead tip located in the right ventricular apex,
such that the conduction pathway is abnormal and slow. Clinical
trials have recently shown that in patients with and without A-V
block, pacing from the right ventricular apex can result in
increased total mortality and re-hospitalization for heart failure
compared to non-paced patients. The possible adverse effects of
pacing the right ventricular apex in patients without
bi-ventricular pacemakers is unknown, but a source of growing
concern.
[0013] 2. Description of the Background Art
[0014] This application has disclosure related to prior commonly
assigned provisional applications 60/479,347 (Attorney Docket No.
21834-000100US), filed on Jun. 17, 2003; 60/496,184 (Attorney
Docket No. 21834-000110US), filed on Aug. 18, 2003; 60/496,179
(Attorney Docket No. 21834-000200US), filed on Aug. 18, 2003; and
60/507,719 (Attorney Docket No. 21834-000300US), filed on Sep. 30,
2003. The full disclosures of each of these prior filings are
incorporated herein by reference. [0015] U.S. Pat. No.
4,928,688/RE38,119 Mower; Method and apparatus for treating
hemodynamic dysfunction. [0016] U.S. Pat. No. 5,174,289 Cohen:
Pacing systems and methods for control of the ventricular
activation sequence. [0017] U.S. Pat. No. 5,018,523 Bach et al.;
Apparatus for common mode stimulation with bipolar sensing. [0018]
U.S. Pat. No. 6,070,101 Struble et al.; Multiple channel,
sequential, cardiac pacing systems. [0019] U.S. Pat. No. 6,439,236
Porter and Xie; Methods of inducing atrial and ventricular rhythms
using ultrasound and microbubbles. [0020] PCT WO 03/070323 Adam et
al; Ultrasound Cardiac Stimulator. [0021] U.S. Pat. No. 6,223,079
Bakels et al.; Bi-ventricular pacing method. [0022] U.S. Pat. No.
4,651,716 Forester et al.; Method and device for enhancement of
cardiac contractility. [0023] PCT WO 9961058 Van der Wouw; Method
of altering heart beat. [0024] ACC/AHA Task Force on Practice
Guidelines. Evaluation and Management of Chronic Heart Failure in
the Adult. JACC 2002;38:2101-13. [0025] Daubert et al., "Use of
Specifically Designed Coronary Sinus Leads for Permanent Left
Ventricular Pacing: Preliminary Experience", PACE, 1997; 20: II-
NASPE Abstract 17, Apr., 1997. [0026] Leclerq C et. al., "Acute
Hemodynamic Effects of Biventricular DDD Pacing in Patients with
End-Stage Heart Failure", JACC 1998;32: 1825-1831. [0027] Daubert
et al., "Permanent Left Ventricular Pacing With Transvenous Leads
Inserted Into The Coronary Veins", PACE 1998;21;239-245. [0028]
Daoud et al., "Implantation Techniques and Chronic Lead Parameters
of Biventricular Pacing Dual-chamber Defibrillators", J Cardiovasc
Electrophysiology 2002; 13:964-970. [0029] Valls-Bertault et al.,
"Adverse Events with Transvenous Left Ventricular Pacing in
Patients with Severe Heart Failure: Early Experience from a Single
Centre", Europace 2001 ;3:60-63. [0030] Leclercq C et al.,
"Systolic Improvement and Mechanical Resynchronization does not
Require Electrical Synchrony in the Dilated Failing Heart with Left
Bundle-Branch Block", Circulation 2002; 106:1760-1763. [0031] Linde
C et al., "Long-Term Benefits of Biventricular Pacing in Congestive
Heart Failure: From the Multisite Stimulation In Cardiomyopathy
(MUSTIC) Study", J Am Coll Cardiol 2002;40:111-118. [0032] Abraham
WT et al., "Cardiac Resynchronization in Chronic Heart Failure", N
Engl J Med 2002;346: 1845-1853. [0033] Bradley DJ et al., "Cardiac
Resynchronization and Death from Progressive Heart Failure: A
Meta-Analysis of Randomized Controlled Trials," JAMA
2003;289:730-740. [0034] Nielsen JC et al., "A Randomized
Comparison of Atrial and Dual-Chambered Pacing in 177 Consecutive
Patients with Sick Sinus Syndrome," J Am Coll Cardiol
2003;42:614-623. [0035] DAVID Trial Investigators, "The Dual
Chamber and VVI Implantable Defibrillator (DAVID) Trial," JAMA
2002;288:3115-3123. [0036] MIRACLE Trial Investigators, "Combined
Cardiac Resynchronization and Implantable Cardioversion
Defibrillation in Advanced Heart Failure: the MIRACLE ICD Trial,"
JAMA 2003;289:2685-2694.
BRIEF SUMMARY OF THE INVENTION
[0037] For this invention, the use of a device to effect left
ventricular pacing and/or to synchronize left ventricular pacing
with right ventricular activation provides an improved method of
treating patients with heart failure or possibly of preventing
heart failure. The improvement uses vibrational energy to effect
left ventricular pacing to the left ventricle without the use of an
implanted intracardiac or epicardial lead in contact with the left
ventricle. Optionally, a system and method of the present invention
may rely on delivery of the vibrational energy from an external
source to provide temporary left ventricular pacing treatment for
heart failure. The system described is a fully implanted
subcutaneous device that provides ultrasound energy at frequencies,
amplitudes, and treatment durations that stimulate cardiac tissue
without the use of leads contacting left ventricular tissue.
[0038] A treatment regime for providing synchronized beating of the
left and right ventricle is accomplished in part by applying a
vibrational energy wave. The vibrational wave stimulates the heart.
Once stimulated, a QRS complex can be seen on an electrocardiogram
and contraction of the heart chamber(s) is initiated. In this
invention, the wave will either a) simultaneously stimulate both
ventricles to contract, b) stimulate the ventricles in a preferred,
more physiologic, conduction pattern, or c) be delivered in
coordination with an electrical pacing and sensing lead, such that
one ventricle is electrically paced and the vibrational wave
stimulates the other ventricle. Vibrational energy offers the
potential benefit of being able to stimulate without tissue
contact, and, therefore, is not limited to the right ventricular
apex as a pacing site nor does it require direct placement and
contact of a lead in or on the left ventricle.
[0039] The vibrational wave can be applied to stimulate each heart
beat with ultrasound as a single burst or as multiple bursts with
appropriate selection of the following parameters: TABLE-US-00001
Parameter Value Range Ultrasound frequency 20 KHz-5 MHz Burst
Length (#cycles) 3-250 Pace Pulse Duration 0.12 .mu.S-13 mS Duty
Cycle 0.1-100% Intensity >0.2 W/cm.sup.2
[0040] The device would contain one or more ultrasound transducers
of appropriate size and aperture to stimulate heart tissue within
the ultrasound beam. The transducer portion of the device would be
implanted subcutaneously in the anterior chest surface of the body
in such fashion as to target the desired heart tissue within the
beam profile of the transducer. The beam profile would need only
target a sufficient volume of tissue to generate a
vibrationally-induced paced beat. If the tissue volume required for
stimulation is small, a narrow beam could used. However, a wide
beam could also be used and could successfully stimulate multiple
chambers simultaneously. Furthermore, multiple beams could be
utilized to stimulate multiple sites within the heart, either
simultaneously or sequentially per a programmable delay
function.
[0041] In a combined electrical pacing and vibrational pacing
device, the synchronization of the delivery could be accomplished
either within a single enclosure or in two separate enclosures.
Separate enclosures would require communication between the devices
to synchronize the beats or detection of an electrically-paced beat
by one device and an immediate vibrationally-paced beat response by
the other device, or vice-versa.
[0042] As in all pacemaker devices, which include a variety of
pacing modalities, the delivery of the vibrational pacing energy
could be triggered based on sensed or programmed heart rates or
inhibited by sensed cardiac events in the atrium or ventricle. When
used for bi-ventricular pacing, with vibrational pacing of the left
ventricle in combination with electrical pacing of the right
ventricle, the vibrational energy would be triggered to be
synchronous, i.e. simultaneous or at a programmable delay, from the
right ventricle electrically-paced beat. Fundamentally, if a right
ventricular beat is triggered or sensed by the vibrational device,
then vibrational energy is delivered to the left ventricle to
synchronize the chambers.
[0043] In the simplest form, the device would contain a vibrational
energy delivery mechanism to stimulate the left ventricle. It would
provide a fixed programmable heart rate that stimulates a paced
beat of the left ventricle via vibrational energy. The paced beat
would then normally conduct to the right ventricle. This would be
analogous to a ventricular pacing and sensing (with inhibition)
referred to as a VVI pacing modality. An enhanced pacing modality
referred to as VVI/T also includes programmability to trigger a
paced beat in response to a sensed beat.
[0044] In a more complex form, the device would contain multiple
vibrational energy mechanisms to stimulate the heart tissue at
multiple points, e.g., at multiple locations within the left
ventricle, and/or within both the left and right ventricles.
Stimulation could occur either simultaneously, or sequentially per
a programmable function.
[0045] In the most complex form, the device would contain a
vibrational energy delivery mechanism for left ventricular
stimulation and also contain electrical capabilities for pacing and
sensing of both right atrial and right ventricular chambers with
programmable capabilities for all combinations of pacing modalities
(e.g. DDDR+, Dual chamber pacing, Dual chamber sensing, Dual
chamber triggered and inhibited modes with Rate responsive sensors
and mode adaptation). Optionally, the device would contain the
capability for high energy delivery used for cardioversion and
defibrillation, using either electrical energy or vibrational
energy.
BRIEF DESCRIPTION OF THE DRAWINGS
[0046] FIGS. 1A and 1B illustrate two embodiments with one or more
right-sided transvenous leads; a left-sided transducer over or
between the ribs with a left-sided canister implant (FIG. 1A), and
a medial transducer placement over the sternum with a right-sided
canister implant (FIG. 1B).
[0047] FIG. 2A and 2B illustrate an alternative embodiment without
leads and a canister housing the ultrasound transducer implanted in
the left precordial subcutaneous space.
[0048] FIGS. 3A and 3B illustrate an alternative embodiment with
one or more subcutaneous leads attached to a canister implanted in
the left precordial subcutaneous space.
[0049] FIG. 4 illustrates an alternative embodiment with two
right-sided transvenous leads, a ventricular lead incorporating a
transducer within the lead body and an atrial lead, and a canister
in the right subcutaneous space.
[0050] FIG. 5 illustrates a lead design incorporating an electrode
pair at the distal end for pacing and sensing, and one or more
transducers within the body of the lead.
[0051] FIG. 6 is a block diagram showing an embodiment of the
control circuitry implementation of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0052] In one exemplary embodiment, all the device sensing, logic
and energy source components are housed within a single canister 10
implanted beneath skin and adipose tissue in the left (FIG. 1A) or
right (FIG. 1B) subclavian region of the chest wall. In this
embodiment, electrical leads 12 containing electrodes are passed
transvenously through the superior vena cava into the right atrium
and/or right ventricle. An ultrasound transducer 14 is separately
connected to the canister by a cable 16. The transducer is encased
in an appropriate housing and is subcutaneously implanted over the
ribs, over the sternum, or between the ribs in order to target the
preferred region of the left or right ventricle within the
ultrasound beam profile. The connecting cable 16 is tunneled
subcutaneously to the canister and connected.
[0053] Alternatively, two canisters may be implanted subcutaneously
beneath skin and adipose tissue (not shown). The first canister
houses the device sensing, logic and energy source components
required for the electrical pacemaker/cardioverter/defibrillator
and may be implanted on the left or right subclavian regions. The
second canister is located in the left anterior chest region over
the ribs or between the ribs or it is located over the sternum. The
second canister houses the transducer, device sensing, logic, and
energy source for pacing using vibrational energy. A connecting
cable is tunneled subcutaneously between the two canisters.
[0054] In another embodiment, (FIGS. 2A and 2B), the device 20 is a
single canister with no transvenous leads. As previously disclosed
the device can be subcutaneously implanted in the left anterior
chest region or over the sternum with the ultrasound beam(s)
directed to the ventricle(s) from a transducer within the canister.
This represents a programmable rate VVI/T device that paces only
the left ventricle or simultaneously or sequentially paces the left
and right ventricles using vibrational energy. An electrocardiogram
sensing circuit would preferably be provided in this embodiment
with electrodes on the surface of the canister, and would provide
either an inhibited pacing operation with a detected ventricular
beat or a synchronized pacing operation with a detected ventricular
beat.
[0055] In another embodiment, (FIGS. 3A and 3B), the device 22 is a
single canister housing the sensing, logic, and energy source
components for pacing using vibrational energy. One or more
subcutaneous leads 24 and 26 containing one or more vibrational
energy elements arranged linearly or in another pattern are
connected to device 22. Electrodes for sensing of the
electrocardiogram (sensors) are provided on either or both leads 24
and 26 or the surface of the canister. This represents an
alternative programmable rate VVI/T device that paces either the
left ventricle or simultaneously or sequentially paces the left and
right ventricles using vibrational energy.
[0056] In another embodiment (FIG. 4), the device 30 is a single
canister with transvenous lead 32 containing capability for
electrical sensing and pacing and transvenous lead 34 containing
capability for electrical sensing and pacing and vibrational
pacing. The single canister 30 would be implanted beneath skin and
adipose tissue in the left or right subclavian region. In this
embodiment, the right ventricular lead 34 (FIG. 5) containing both
electrical and vibrational energy components, and a right atrial
lead 32 containing electrical energy components are utilized. The
leads are passed transvenously through the superior vena cava into
the right ventricle and the right atrium. In this embodiment
transducer(s) 36 would be contained within the body of the right
ventricular lead. The transducer(s) 36 would deliver vibrational
energy to pace one or both ventricles. The electrical component of
the right ventricular lead would primarily be used for sensing, but
could optionally be used for electrical pacing. The right atrial
lead would be used for both sensing and pacing.
[0057] Another embodiment would be similar to FIG. 4, except that
both the right atrial lead 32 and right ventricular lead 34 would
contain both electrical 37 and 38 and vibrational 36 energy
components as shown in FIG. 5. In this embodiment, the right atrial
lead would function in a manner similar to the right ventricular
lead, to accomplish pacing and sensing of the right and left
atria.
[0058] Alternatively, the right atrial lead 32 would not be
present, and the right ventricular lead would be as shown in FIG. 5
with an added electrical sensing electrode (not shown) located on a
proximal portion of the lead such that the electrode would be
positioned within the right atrium.
[0059] Alternatively, the right atrial lead would not be present,
and the right ventricular lead would be as shown in FIG. 5 with an
added electrical sensing electrode (not shown) and with an added
vibrational energy transducer (not shown) located on a proximal
portion of the lead such that the components would be positioned
within the right atrium. In this embodiment a single lead could
provide pacing and sensing of the right and left atria and
separately pacing and sensing of the right and left ventricles.
[0060] FIG. 6 provides a block diagram of circuitry for
implementing the most complex version of the device including dual
chamber sensing, dual chamber electrical pacing, electrical
cardioversion and defibrillation, and vibrational energy pacing.
Alternatively, the cardioversion and defibrillation may be provided
by vibrational energy.
[0061] The device designs and implementations referred to thus far
are generally useful for the treatment of patients with heart
failure. The treatment of heart failure, however, may be
accomplished with systems which may be somewhat simpler that those
described above to promote temporary synchronized contraction of
the ventricles. In particular, the vibrational transducers may be
adapted for manual control by either the patient or by a doctor or
other medial personnel. Most simply, the vibrational transducer may
be incorporated into external units capable of being applied to the
anterior chest (not shown). Usually, the patient will be reclining
on the table or bed, the vibrational transducer, attached by a
cable to an external generator, is applied over the patient's
chest, preferably using a gel layer to enhance contact. Usually,
the transducer will be placed generally over the ventricular region
of the heart and the transducer may be configured to direct energy
over specific ventricular regions.
[0062] Systems embodied for external use have sensor circuitry,
control circuitry, power supply, and burst generation incorporated
into the generator (not shown). The ECG sensors may be incorporated
into the transducer housing or optionally standard transcutaneous
electrodes may be connected to the body and to the generator via
cables. Alternatively, the generator may accept ECG signals
directly from an external electrocardiogram system. Intrinsic heart
signals detected from ECG sensors are analyzed by control circuitry
and are used to control pacing using the vibrational energy as
discussed above for implantable systems.
* * * * *