U.S. patent application number 11/903256 was filed with the patent office on 2008-03-20 for method and apparatus for identifying patients with wide qrs complexes.
This patent application is currently assigned to Cardiac Pacemakers, Inc.. Invention is credited to Michael Gebauer, Jay Millerhagen, Brian P. Thomas.
Application Number | 20080071183 11/903256 |
Document ID | / |
Family ID | 36780894 |
Filed Date | 2008-03-20 |
United States Patent
Application |
20080071183 |
Kind Code |
A1 |
Thomas; Brian P. ; et
al. |
March 20, 2008 |
Method and apparatus for identifying patients with wide QRS
complexes
Abstract
A medical device programmer or other external system capable of
programming an implantable CRM device includes a wide-QRS detection
and alerting system. Upon detection of a wide QRS complex, a
wide-QRS indicator produces a visual indication of the detection
using one or more presentation devices such as a display screen and
a printer to alert a physician or other caregiver.
Inventors: |
Thomas; Brian P.; (Blaine,
MN) ; Millerhagen; Jay; (Lino Lakes, MN) ;
Gebauer; Michael; (Woodbury, MN) |
Correspondence
Address: |
SCHWEGMAN, LUNDBERG & WOESSNER, P.A.
P.O. BOX 2938
MINNEAPOLIS
MN
55402
US
|
Assignee: |
Cardiac Pacemakers, Inc.
4100 Hamline Avenue North
ST Paul
MN
55112-5798
|
Family ID: |
36780894 |
Appl. No.: |
11/903256 |
Filed: |
September 20, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11055731 |
Feb 10, 2005 |
7283864 |
|
|
11903256 |
Sep 20, 2007 |
|
|
|
Current U.S.
Class: |
600/516 |
Current CPC
Class: |
G16H 40/63 20180101;
A61N 1/37247 20130101; A61B 5/366 20210101; A61N 1/37258
20130101 |
Class at
Publication: |
600/516 |
International
Class: |
A61B 5/0472 20060101
A61B005/0472 |
Claims
1. An external system configured to be communicatively coupled to
an implantable medical device, the external system comprising: an
external telemetry circuit configured to communicate with the
implantable medical device; a user interface coupled to the
external telemetry circuit, the user interface including a screen;
and a wide-QRS detection and alerting circuit coupled to the user
interface, the wide-QRS detection and alerting circuit including: a
wide-QRS detector including a signal input to receive an
electrocardiogram (ECG) signal, a QRS width measurement module
configured to measure the QRS width using the received ECG signal,
and a QRS width comparator having a first input to receive the
measured QRS width, a second input to receive a threshold QRS
width, and an output indicative of a detection of a wide QRS
complex when the measured QRS width exceeds the threshold QRS
width; and a wide-QRS indicator coupled to the wide-QRS detector,
the wide-QRS indicator including an image generator configured to
present a message window on the screen in response to the detection
of the wide QRS complex, the message window displaying a message
indicative of the detection of the wide QRS complex.
2. The system of claim 1, further comprising a programming circuit
coupled to the external telemetry circuit and the user interface,
the programming circuit configured to program the implantable
medical device, and the user interface comprises a programming
input device configured to receive user input from a user, the user
input related to programming of the implantable medical device.
3. The system of claim 1, further comprising a surface ECG sensing
circuit configured to sense a surface ECG signal using surface ECG
electrodes, and wherein the signal input is programmable for
receiving one of the surface ECG signal and a wireless ECG signal
transmitted from the implantable medical device, the wireless ECG
signal being a signal sensed by the implantable medical device
using implantable electrodes.
4. The system of claim 1, wherein the user interface comprises a
threshold input device configured to receive the threshold QRS
width from a user.
5. The system of claim 4, wherein the threshold input device is
configured to allow the user to type in the threshold QRS
width.
6. The system of claim 4, wherein the threshold input device is
configured to allow the user to select from a plurality of
predetermined threshold QRS widths.
7. The system of claim 1, comprising an external device
communicatively coupled to the implantable medical device via the
telemetry, a remote device, and a telecommunication network coupled
between the external device and the remote device.
8. The system of claim 7, wherein the remote device comprises the
screen.
9. The system of claim 1, wherein the image generator is configured
to cause a text message to be displayed in the message window, the
text message directly indicative of the detection of the wide QRS
complex.
10. The system of claim 9, wherein the image generator is
configured to cause the measured QRS width to be displayed in the
message window.
11. The system of claim 9, wherein the user interface comprises a
printer, and the wide-QRS indicator comprises a message generator
configured to produce a message indicative of the detection of the
wide QRS complex to be printed by the printer.
12. A method for operating an external system configured to
communicate with an implantable medical device implanted in a
patient, the method comprising: receiving an electrocardiogram
(ECG) signal sensed from the patient; measuring a QRS width from
the received ECG signal; detecting a wide QRS complex by comparing
the measured QRS width to a threshold QRS width; and presenting a
message window on a display screen of the external system in
response to a detection of the wide QRS complex, the message window
displaying a message indicative of the detection of the wide QRS
complex.
13. The method of claim 12, comprising sensing a surface ECG signal
using surface ECG electrodes attached onto an exterior surface of
the patient's skin, and wherein receiving the ECG signal comprises
receiving the sensed surface ECG signal.
14. The method of claim 12, comprising sensing a wireless ECG
signal using the implantable medical device and implantable ECG
electrodes implanted in the patient, and wherein receiving the ECG
signal comprises receiving the sensed wireless ECG signal from the
implantable medical device via telemetry.
15. The method of claim 14, wherein sensing the wireless ECG signal
comprises sensing the wireless ECG signal using subcutaneous
electrodes attached to the implantable medical device.
16. The method of claim 12, further comprising programming the
implantable medical device to adjust one or more therapy parameters
in response to the detection of the wide QRS complex.
17. The method of claim 12, comprising receiving the threshold QRS
width from a user using a user input device of the external
system.
18. The method of claim 12, comprising displaying a text message in
the message window, the text message directly indicative of the
detection of the wide QRS complex.
19. The method of claim 18, comprising displaying the measured QRS
width in the message window.
20. The method of claim 18, comprising printing a message
indicative of the detection of the wide QRS complex using a printer
of the external system.
Description
RELATED APPLICATION
[0001] This application is a continuation of U.S. patent
application Ser. No. 11/055,731, filed Feb. 10, 2005, which is
incorporated herein by reference in its entirety.
TECHNICAL FIELD
[0002] This document generally relates to cardiac rhythm management
(CRM) systems and particularly, but not by way of limitation, to
such a system that identifies patients with wide QRS complexes.
BACKGROUND
[0003] The heart is the center of a person's circulatory system.
The left portions of the heart, including the left atrium (LA) and
left ventricle (LV), draw oxygenated blood from the lungs and pump
it to the organs of the body to provide the organs with their
metabolic needs for oxygen. The right portions of the heart,
including the right atrium (RA) and right ventricle (RV), draw
deoxygenated blood from the body organs and pump it to the lungs
where the blood gets oxygenated. These mechanical pumping functions
are accomplished by contractions of the heart. In a normal heart,
the sinoatrial (SA) node, the heart's natural pacemaker, generates
electrical impulses, called action potentials, that propagate
through an electrical conduction system to various regions of the
heart to cause the muscular tissues of these regions to depolarize
and contract at a normal sinus rate.
[0004] Electrocardiography (ECG) is known to indicate the functions
of the electrical conduction system by monitoring the action
potentials at various portions of the heart. A QRS complex is a
segment of an ECG signal that indicates depolarization of the
ventricles. An abnormally wide QRS complex is an indication that
the conduction of the electrical impulses through the ventricles is
prolonged. The prolonged conduction may result from conditions
related to heart failure, including hypertrophy or dilatation of
one or both ventricles and/or blockage of the Purkinje fibers that
conduct the electrical impulses in the ventricles. Thus, physicians
and other caregivers use the width of the QRS complex as an
indication of abnormal cardiac conditions, including heart failure,
that may need medical treatments.
[0005] Implantable CRM devices such as pacemakers and
defibrillators are used to treat cardiac arrhythmias, heart
failure, and other cardiovascular disorders by delivering
electrical energy to the heart. An abnormally wide QRS complex is
one of the factors that prompt a physician or other caregiver to
consider an application or adjustment of a cardiac electrical
therapy using an implantable CRM device.
[0006] For these and other reasons, there is a need for an easy and
convenient way to detect wide QRS complexes and, if detected,
communicate the result to a physician or other caregiver for
consideration of applying or adjusting the cardiac electrical
therapy.
SUMMARY
[0007] A medical device programmer or other external system capable
of programming an implantable CRM device includes a wide-QRS
detection and alerting system. Upon detection of a wide QRS
complex, a wide-QRS indicator produces a visual indication of the
detection using one or more presentation devices such as a display
screen and a printer to alert a physician or other caregiver.
[0008] In one embodiment, a CRM system includes an implantable
medical device and an external system communicatively coupled to
the implantable medical device via telemetry. The implantable
medical device includes a pacing circuit to deliver pacing pulses
and an implant controller to control the delivery of the pacing
pulses. The external system includes a user interface, a
programming circuit, and a wide-QRS detection and alerting circuit.
The user interface includes one or more user input devices and one
or more presentation devices. The programming circuit allows for
programming of the implantable medical device. The wide-QRS
detection and alerting circuit includes a wide-QRS detector and a
wide-QRS indicator. The wide-QRS detector receives an ECG signal
and detects a wide QRS complex from the ECG signal. The wide-QRS
indicator produces a wide-QRS indication using the one or more
presentation devices when the wide QRS complex is detected.
[0009] In one embodiment, a medical device programmer includes an
external telemetry circuit, a user interface, a programming
circuit, a surface ECG sensing circuit, and a wide-QRS detection
and alerting circuit. The external telemetry circuit allows the
medical device programmer to communicate with an implantable
medical device. The user interface includes one or more user input
devices and one or more presentation devices. The programming
circuit allows for the programming of the implantable medical
device. The surface ECG sensing circuit senses at least one surface
ECG signal. The wide-QRS detection and alerting circuit includes a
wide-QRS detector and a wide-QRS indicator. The wide-QRS detector
receives the surface ECG signal and detects a wide QRS complex from
the surface ECG signal. The wide-QRS indicator produces a wide-QRS
indication using the one or more presentation devices when the wide
QRS complex is detected.
[0010] In one embodiment, an external system communicates with an
implantable medical device coupled to implantable electrodes. The
external system includes an external telemetry circuit, a
programming circuit, a user interface, and a wide-QRS detection and
alerting circuit. The external telemetry circuit receives at least
one wireless ECG signal from the implantable medical device. The
wireless ECG signal is a signal sensed through the implantable
electrodes and approximating a surface ECG signal. The programming
circuit allows for programming of the implantable medical device.
The user interface includes one or more presentation devices. The
wide-QRS detection and alerting circuit includes a wide-QRS
detector and a wide-QRS indicator. The wide-QRS detector receives
the wireless ECG signal and detects a wide QRS complex from the
wireless ECG signal. The wide-QRS indicator produces a wide-QRS
indication using the one or more presentation devices when the wide
QRS complex is detected.
[0011] In one embodiment, a method is provided for operating a
medical device programmer communicating with an implantable medical
device. A surface ECG signal is sensed by using a surface ECG
sensing circuit of the medical device programmer. A QRS width is
measured from the surface ECG signal. A wide QRS complex is
detected by comparing the measured QRS width to a predetermined
threshold QRS width. When the QRS width exceeds the predetermined
threshold QRS width, a visual indication of a detection of the wide
QRS complex is presented using a presentation device of the medical
device programmer.
[0012] In one embodiment, a method is provided for operating an
external system communicating with an implantable medical device
coupled to implantable electrodes. A wireless ECG signal is
received from the implantable medical device. The wireless ECG is a
signal sensed through the implantable electrodes and approximating
a surface ECG. A QRS width is measured from the wireless ECG
signal. A wide QRS complex is detected by comparing the QRS width
to a predetermined threshold QRS width. When the QRS width exceeds
the predetermined threshold QRS width, a visual indication of a
detection of the wide QRS complex is presented using a presentation
device of the external system.
[0013] This Summary is an overview of some of the teachings of the
present application and not intended to be an exclusive or
exhaustive treatment of the present subject matter. Further details
about the present subject matter are found in the detailed
description and appended claims. Other aspects of the invention
will be apparent to persons skilled in the art upon reading and
understanding the following detailed description and viewing the
drawings that form a part thereof, each of which are not to be
taken in a limiting sense. The scope of the present invention is
defined by the appended claims and their equivalents.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] In the drawings, which are for illustrative purposes only
and not necessarily drawn to scale, like numerals describe similar
components throughout the several views. The drawings illustrate
generally, by way of example, but not by way of limitation, various
embodiments discussed in the present document.
[0015] FIG. 1 is an illustration of an embodiment of a CRM system
and portions of an environment in which the CRM system is used.
[0016] FIG. 2 is a block diagram illustrating an embodiment of a
circuit of the CRM system.
[0017] FIG. 3 is a block diagram illustrating an embodiment of a
user interface of the CRM system.
[0018] FIG. 4 is a block diagram illustrating an embodiment of a
wide-QRS detection and alerting circuit of the CRM system.
[0019] FIG. 5 is an illustration of an embodiment of the CRM system
including an external patient management system and portions of the
environment in which the CRM system is used.
[0020] FIG. 6 is a flow chart illustrating one embodiment of a
method for detecting and indicating wide QRS complexes using a
medical device programmer.
[0021] FIG. 7 is a flow chart illustrating one embodiment of a
method for detecting and indicating wide QRS complexes based on a
wireless ECG signal sensed by an implantable medical device.
DETAILED DESCRIPTION
[0022] In the following detailed description, reference is made to
the accompanying drawings that form a part hereof, and in which is
shown by way of illustration specific embodiments in which the
invention may be practiced. These embodiments are described in
sufficient detail to enable those skilled in the art to practice
the invention, and it is to be understood that the embodiments may
be combined, or that other embodiments may be utilized and that
structural, logical and electrical changes may be made without
departing from the spirit and scope of the present invention. The
following detailed description provides examples, and the scope of
the present invention is defined by the appended claims and their
equivalents.
[0023] It should be noted that references to "an", "one", or
"various" embodiments in this document are not necessarily to the
same embodiment, and such references contemplate more than one
embodiment. In this document, "electrogram" or "intracardiac
electrogram" refers to a cardiac electrical signal sensed with one
or more implantable sensing electrodes placed in or on the heart.
"Surface ECG" refers to a cardiac electrical signal sensed with
electrodes attached onto the exterior surface of the skin.
"Wireless ECG" refers to a signal approximating the surface ECG,
acquired without using surface (non-implantable, skin contact)
electrodes. "Subcutaneous ECG" is a form of wireless ECG and
includes a cardiac electrical signal sensed through electrodes
implanted in subcutaneous tissue, such as through electrodes
incorporated onto an implantable medical device that is
subcutaneously implanted. A surface ECG is morphologically
different from an intracardiac electrogram because of the
difference in the sources that produce these signals. As reflected
in their corresponding morphologies, the surface ECG results from
electrical activities of the entire heart, while the intracardiac
electrogram primarily results from the spread of electrical
activity in a region in close proximity to the one or more
implantable sensing electrodes placed in or on the heart. The
wireless ECG, including but not being limited to the subcutaneous
ECG, has a morphology that approximates that of the surface ECG and
reflects electrical activities of a substantial portion of the
heart, up to the entire heart.
[0024] This document discusses, among other things, a CRM system
that automatically identifies patients with wide QRS complexes. A
wide QRS complex is a QRS complex having a width that exceeds a
threshold QRS width. The CRM system includes an implantable medical
device and a medical device programmer or other external system
communicating with the implantable medical device. When a wide QRS
complex is detected, the medical device programmer or other
external system provides a physician or other caregiver with a
conspicuous visual indication using one or more presentation
devices such as a display screen and a printer.
[0025] FIG. 1 is an illustration of one embodiment of a CRM system
100 and portions of the environment in which CRM system 100 is
used. System 100 includes an implantable medical device 110, a lead
system 108, an external system 130, a wireless telemetry link 125,
surface ECG electrodes 106A-D, and an ECG lead cable 107.
[0026] After implantation, implantable medical device 110 operates
within a body 102 to sense activities of a heart 105 and deliver
one or more therapies to heart 105. Implantable medical device 110
includes, but is not limited to, one or more of a pacemaker, a
cardioverter/defibrillator, a cardiac resynchronization therapy
(CRT) device, a cardiac remodeling control therapy (RCT) device, a
drug delivery device, and a biological therapy device.
[0027] Lead system 108 provides one or more electrical and/or other
connections between implantable medical device 110 and heart 105.
In one embodiment, lead system 108 includes one or more pacing
and/or defibrillation leads each having one or more electrodes for
sensing cardiac electrical signals and/or delivering electrical
pulses to heart 105. In one embodiment, one or more intracardiac
sensors are incorporated into lead system 108 to sense signals such
as heart sounds, intracardiac pressures, and chemical parameters of
the blood.
[0028] In one embodiment, implantable medical device 110 is capable
of sensing one or more wireless ECG signals and transmitting them
to external device 130. The one or more wireless ECG signals are
sensed using electrodes incorporated into lead system 108 and/or
electrodes incorporated onto implantable medical device 110. In one
specific embodiment, the one or more wireless ECG signals include
one or more subcutaneous ECG signals sensed through implantable
subcutaneous electrodes.
[0029] External system 130 communicates with implantable medical
device 110 through telemetry link 125. External system 130 allows a
physician or other caregiver to communicate with implantable
medical device 110. External system 130 includes a programming
circuit 140, a wide-QRS detection and alerting circuit 160, and a
user-interface 180. Programming circuit 140 allows the physician or
other caregiver to program implantable medical device 110. Wide-QRS
detection and alerting circuit 160 detects a wide QRS complex,
i.e., a QRS complex having a width or duration that is longer than
a predetermined threshold, from an ECG signal indicative of cardiac
electrical activities of heart 105 and produces a visual indication
of each detection of a wide QRS complex for presentation on user
interface 180. In one embodiment, the ECG signal is a wireless ECG
signal sensed by implantable medical device 110. In another
embodiment, the ECG signal is sensed through surface electrodes
106A-D, which are connected to external system 130 through an ECG
lead cable 107.
[0030] In one embodiment, external system 130 includes an external
medical device programmer. The medical device programmer includes
programming circuit 140, the wide-QRS detection and alerting
circuit 160, and user interface 180. In another embodiment,
external system 130 is a patient management system including an
external device, a telecommunication network, and a remote device.
The external device is placed within the vicinity of implantable
medical device 110 and communicates with implantable medical device
110 bi-directionally via telemetry link 125. The remote device is
in a remote location and communicates with the external device
bi-directionally through the telecommunication network, thus
allowing a physician or other caregiver to monitor and treat a
patient from a distant location. In one embodiment, the remote
device includes at least portions of programming circuit 140, the
wide-QRS detection and alerting circuit 160, and user interface
180.
[0031] Telemetry link 125 provides for communication between
implantable medical device 110 and external system 130. In one
embodiment, telemetry link 125 is an inductive telemetry link. In
an alternative embodiment, telemetry link 125 is a far-field
radio-frequency telemetry link. Telemetry link 125 provides for
data transmission from implantable medical device 110 to external
system 130. This may include, for example, transmitting information
indicative of the device type of implantable medical device 110,
transmitting data indicative of the current operational mode(s) and
parameter values, transmitting real-time physiological data
acquired by implantable medical device 110, extracting
physiological data acquired by and stored in implantable medical
device 110, extracting therapy history data, and extracting data
indicating an operational status (e.g., battery status and lead
impedance). Telemetry link 125 also provides for data transmission
from external system 130 to implantable medical device 110. This
may include, for example, parameters for programming implantable
medical device 110 to acquire physiological data, to perform at
least one self-diagnostic test (such as for a battery status and
lead impedance status), and/or to deliver at least one therapy. The
physiological data represent signals acquired by implantable
medical device 110. The signals include, but are not limited to,
one or more of electrograms, wireless ECG signals, heart sounds or
signals indicative of heart sounds, activity level signals,
impedance signals, pressure or pressure-indicating signals, and
respiratory signals. In one embodiment, the physiological data also
include parameters measured from one or more of these signals. In
one embodiment, external system 130 or the physician or other
caregiver determines parameter values for programming implantable
medical device 110 based on these physiological data.
[0032] FIG. 2 is a block diagram illustrating an embodiment of a
circuit of a CRM system 200. CRM system 200 represents one
embodiment of CRM system 100 and includes an implantable medical
device 210 coupled to implantable ECG electrodes 209 and lead
system 108, an external system 230 coupled to surface ECG
electrodes 206, and wireless telemetry link 125. As illustrate in
FIG. 2, CRM system 200 is capable of detecting wide QRS complexes
from either a wireless ECG signal sensed by implantable medical
device 210 through implantable ECG electrodes 209 or a surface ECG
signal sensed by external system 230 through surface ECG electrodes
206. In various specific embodiments, CRM system 200 detects wide
QRS complexes from the wireless ECG signal, the surface ECG signal,
or both.
[0033] Implantable medical device 210 is a specific embodiment of
implantable medical device 110 and includes a pacing circuit 212,
an electrogram sensing circuit 214, a wireless ECG sensing circuit
216, an implant controller 218, and an implant telemetry circuit
224. Pacing circuit 212 delivers pacing pulses to the heart. In one
embodiment, implantable medical device 210 includes one or more
additional therapy delivery devices such as a
cardioversion/defibrillation circuit to deliver
cardioversion/defibrillation pulses, a substance delivery device to
deliver chemical and/or biological agents, and a biological therapy
device to deliver signals controlling a gene therapy. Electrogram
sensing circuit 214 senses one or more electrograms. Wireless ECG
sensing circuit 216 senses one or more wireless ECG signals through
implantable ECG electrodes 209. Implantable ECG electrodes 209
include intracardiac electrodes, epicardial electrodes,
subcutaneous electrodes, or any combination of such electrodes. In
one embodiment, implantable ECG electrodes 209 include subcutaneous
electrodes that are incorporated onto implantable medical device
210. Examples of a circuit and implantable electrodes for sensing
the wireless ECG is discussed in U.S. patent application Ser. No.
10/795,126, entitled "WIRELESS ECG IN IMPLANTABLE DEVICES," filed
on Mar. 5, 2004, assigned to Cardiac Pacemakers, Inc., which is
incorporated herein by reference in its entirety. Implant
controller 218 controls the sensing of the electrograms and
wireless ECG signals and the delivery of pacing pulses and/or other
therapies. In one embodiment, implantable controller 218 includes a
CRT algorithm execution module 220 that controls the delivery of
pacing pulses by executing a CRT algorithm. The CRT pacing
algorithm is executed with one or more pacing parameters
approximately optimized to maximize a measure of hemodynamic
performance. Implant telemetry circuit 224 provides implantable
medical device 210 with the telemetry capability required for
communicating with external device 230 via telemetry link 125.
[0034] External system 230 is a specific embodiment of external
system 130 and includes an external telemetry circuit 226, a
programming circuit 240, a surface ECG sensing circuit 234, a
wide-QRS detection and alerting circuit 260, and a user interface
280. External telemetry circuit 226 provides external system 230
with the telemetry capability required for communicating with
implantable medical device 210 via telemetry link 125. Programming
circuit 240 programs implantable medical device 210 by producing
programming instructions based on user input received through user
interface 280. External telemetry circuit 226 receives these
programming instructions and transmits them to implantable medical
device 210. In one embodiment, external telemetry circuit 226
receives one or more wireless ECG signals from implantable medical
device 210. Surface ECG sensing circuit 234 senses one or more
surface ECG signals using surface ECG electrodes 206. Wide-QRS
detection and alerting circuit 260 includes a wide QRS detector 262
and a wide-QRS indicator 264. Wide QRS detector 262 receives an ECG
signal and detects wide QRS complexes from the ECG signal. In one
embodiment, the ECG signal is a surface ECG signal received from
surface ECG sensing circuit 234. In another embodiment, the ECG
signal is a wireless ECG signal received from external telemetry
circuit 226, which receives that wireless ECG signal from
implantable medical device 210. Wide QRS detector 262 detects the
wide QRS complexes by detecting QRS complexes, measuring the width
of each QRS complex, and comparing the width to a predetermined
threshold QRS width. When a wide QRS complex is detected, wide-QRS
indicator 264 produces a wide-QRS indication for presentation using
user interface 280. Additional details of wide-QRS detection and
alerting circuit 260 are discussed below with reference to FIG. 4.
User interface 280 includes one or more user input devices 282 and
one or more presentation devices 284. User input device(s) 282
allow the physician or other caregiver to control the operation of
implantable medical device 210, and to control the operation of
external system 230 including wide-QRS detection and alerting
circuit 260. Presentation device(s) 282 displays and/or prints
information related to the patient's physiological activities and
conditions, including the wide-QRS indication and information
related to the operation of implantable medical device 210.
Additional details of user interface 280 are discussed below with
reference to FIG. 3.
[0035] FIG. 3 is a block diagram illustrating an embodiment of a
user interface 380. User interface 380 is a specific embodiment of
user interface 280 and includes user input devices 382 and
presentation devices 384. User input devices 382 includes a
programming input device 386 and a threshold input device 387.
Programming input device 386 receives user inputs related to the
programming of implantable medical device 210, such as therapy
commands and parameters, from the physician or other caregiver and
sends the user inputs to programming circuit 240. Threshold input
device 387 receives the threshold QRS width from the physician or
other caregiver and sends the threshold QRS width to wide-QRS
detector 262. In one embodiment, threshold input device 387 allows
the physician or other caregiver to type in the threshold QRS
width. In another embodiment, threshold input device 387 allows the
physician or other caregiver to select from a plurality of
predetermined threshold QRS widths. Presentation devices 384
include a screen 388 and a printer 389. In response to a wide-QRS
indication produced by wide-QRS indicator 264, an alert message
indicating a wide QRS complex is displayed on screen 388 and/or
printed by printer 389. In one embodiment, presentation devices 384
further include a speaker to produce an audio tune to attract
attention from the physician or other caregiver to the detection of
the wide QRS complex.
[0036] FIG. 4 is a block diagram illustrating an embodiment of a
wide-QRS detection and alerting circuit 460. Wide-QRS detection and
alerting circuit 460 is a specific embodiment of wide-QRS detection
and alerting circuit 260 and includes a wide-QRS detector 462 and a
wide-QRS indicator 464. In one embodiment, wide-QRS detection and
alerting circuit 460 detects wide QRS complexes from a surface ECG
signal. In another embodiment, wide-QRS detection and alerting
circuit 460 detects wide QRS complexes from a wireless ECG signal.
In another embodiment, wide-QRS detection and alerting circuit 460
is selectively programmable for detecting wide QRS complexes from
one of a surface ECG and a wireless ECG.
[0037] Wide-QRS detector 462 is a specific embodiment of wide-QRS
detector 262 and includes a signal input 466, a QRS width
measurement module 467, and a QRS width comparator 468. Signal
input 466 receives an ECG signal from which wide QRS complexes are
to be detected. In one embodiment, signal input 466 receives a
surface ECG signal from surface ECG sensing circuit 234. In another
embodiment, signal input 466 receives a wireless ECG signal from
external telemetry circuit 226. In another embodiment, signal input
466 is programmable for either receiving the surface ECG signal
from surface ECG sensing circuit 234 or receiving the wireless ECG
signal from external telemetry circuit 226. QRS width measurement
module 467 measures the QRS width from the ECG signal received by
signal input 466. In one embodiment, QRS width measurement module
467 includes a peak detector and a deviation detector. The peak
detector detects R-wave peaks. The deviation detector detects
points on the ECG signal where the amplitude deviates from its
baseline value. Upon detection of an R-wave peak, QRS width
measurement module 467 measures the time interval between two
adjacent deviation points detected before and after the R-wave
peak. This time interval is the QRS width. In one embodiment, to
measure a QRS width, the peak detector detects an R-wave peak, and
the deviation detector detects the deviation points by assessing a
series of digitized points of the ECG signal before and after the
R-wave peak to determine when the ECG signal deviates from the
baseline by a predetermined percentage, such as approximately 10%.
The deviation points include two points, one before the R-wave peak
and one after the R-wave peak, that are the points closest to the
R-wave peak and where the ECG signal deviates from the baseline by
the predetermined percentage. In one specific embodiment, the
percentage is programmable. The QRS width equals the sampling rate
multiplied by the number of the digitized points (samples) between
the two deviation points. In a further embodiment, QRS width
measurement module 467 measures the QRS width when the R-wave peaks
are detected at a rate between approximately 30 beats per minute to
300 beats per minute, which corresponding to a rate interval of 200
milliseconds to 2 seconds. QRS width comparator 468 has a first
input, a second input, and an output. The first input of QRS width
comparator 468 receives the QRS width from QRS width measurement
module 467. The second input of QRS width comparator 468 receives a
predetermined threshold QRS width. In one embodiment, the second
input receives a predetermined threshold QRS width from threshold
input device 387. In another embodiment, the predetermined
threshold QRS width is a built-in or default value stored in a
storage circuit of external system 230. In one embodiment, the
built-in or default values is used unless and until the physician
or caregiver changes it using threshold input device 387. In one
embodiment, the built-in or default value is about 120
milliseconds. The output of QRS width comparator 468 indicates a
detection of the wide QRS complex when the QRS width exceeds the
predetermined threshold QRS width.
[0038] Wide-QRS indicator 464 is a specific embodiment of wide-QRS
indicator 264 and includes an image generator 470 and a message
generator 471. Image generator 470 produces a visual indication of
the detection of the wide QRS complex to present on screen 388. In
one embodiment, upon detection of the wide QRS complex, image
generator 470 causes a message window to pop up on screen 388. The
window displays a conspicuous message such as "Wide QRS Complex" or
"Attention: Wide QRS." In a further embodiment, image generator 470
also causes the measured QRS width to be displayed in the message
window. Message generator 471 produces a message indicative of the
detection of the wide QRS complex to print by printer 389. In one
embodiment, the message includes a conspicuously printed header
such as "Wide QRS Complex" or "Attention: Wide QRS" followed by the
measured QRS width.
[0039] In one embodiment, external system 230 includes a medical
device programmer. In a specific embodiment, the medical device
programmer detects the wide QRS complex from the surface ECG
signal. The implantable medical device communicating with the
medical device programmer does not necessarily sense a wireless
ECG. In another specific embodiment, the medical device programmer
detects the wide QRS complex from the wireless ECG signal. When the
medical device programmer communicates with an implantable medical
device that senses a wireless ECG, there is no need to attach
surface ECG electrodes and connecting the surface ECG electrodes to
the medical device programmer using an ECG lead cable. In another
specific embodiment, as illustrated in FIG. 2, the medical device
programmer is capable of detecting QRS width from either the
surface ECG signal or the wireless ECG signal. One of the surface
ECG signal and the wireless ECG signal is selected for detecting
wide QRS complexes based on whether the wireless ECG signal is
available and/or the quality of each available ECG signal.
[0040] In another embodiment, external system 230 is a patient
monitoring system that is illustrated in FIG. 5 as external system
530. FIG. 5 is an illustration of an embodiment of a CRM system 500
and portions of an environment in which CRM system 500 is used. CRM
system 500 is a specific embodiment of CRM system 100. External
system 530 includes an external device 590, a remote device 594,
and a telecommunication network 592 coupled between external device
590 and remote device 594. In one embodiment, external system 530
includes the elements of external 230 as illustrated in FIG. 2
except for surface ECG sensing circuit. The distribution of the
elements in external system 530 depends on design and patient
management considerations. In one exemplary embodiment, external
device 590 includes at least external telemetry circuit 226 to
receive the wireless ECG signal from implantable medical device
210. Remote device 594 includes at least wide-QRS indicator 264 and
presentation device(s) 284. Upon detection of the wide QRS complex,
remote device 592 informs the physician or other caregiver in a
location remote from the patient. This allows prompt medical
attention, for example, when the patient's cardiac condition
worsens. In one embodiment, upon detection of the wide QRS complex,
external system 530 programs implantable medical device 210 to
adjust a therapy, such as to start delivering pacing pulses by
executing the CRT algorithm.
[0041] FIG. 6 is a flow chart illustrating one embodiment of a
method for detecting and indicating wide QRS complexes using a
medical device programmer communicating with an implantable medical
device. A surface ECG is sensed, at 600, using a surface ECG
sensing circuit of the medical device programmer. A QRS width is
measured from the surface ECG signal at 610. A wide QRS complex is
detected by comparing the QRS width to a predetermined threshold
QRS width at 620. When the QRS width exceeds the predetermined
threshold QRS width, a visual indication of a detection of the wide
QRS complex is presented, at 630, using a presentation device of
the medical device programmer. In one embodiment, the visual
indication of the detection of the wide QRS complex is presented on
a display screen of the medical device programmer. In another
embodiment, a message indicative of the detection of the wide QRS
complex is printed using a printer of the medical device
programmer.
[0042] In one embodiment, the predetermined threshold QRS width is
stored in the medical device programmer. In a further embodiment,
the store threshold QRS threshold is a default value that is
changed when another threshold QRS width is received through a user
input device of the medical device programmer.
[0043] In one embodiment, the implantable medical device is
programmed to adjust a therapy delivery, and the QRS width is
measured after the therapy delivery is adjusted. For example, to
detect wide QRS complexes based on intrinsic (non-paced) QRS widths
of a patient receiving a pacing therapy, the physician or other
caregiver programs the implantable medical device to stop the
delivery of the pacing therapy using the medical device programmer.
To evaluate the effect of pacing or one or more pacing parameters
in the QRS width, the physician or other caregiver programs the
implantable medical device to start the delivery of the pacing
therapy and/or to adjust one or more pacing parameters using the
medical device programmer.
[0044] FIG. 7 is a flow chart illustrating one embodiment of a
method for detecting and indicating wide QRS complexes based on a
wireless ECG signal sensed by an implantable medical device. The
wireless ECG signal is received from the implantable medical device
at 700. In one embodiment, the wireless ECG is a subcutaneous ECG
signal sensed through subcutaneous electrodes attached to the
implantable medical device. A QRS width is measured from the
wireless ECG signal at 710. A wide QRS complex is detected, at 720,
by comparing the QRS width to a predetermined threshold QRS width.
When the QRS width exceeds the predetermined threshold QRS width, a
visual indication of a detection of the wide QRS complex is
presented, at 730, using a presentation device of an external
system communicating with the implantable medical device. In one
embodiment, the visual indication of the detection of the wide QRS
complex is presented on a display screen of the external system. In
another embodiment, a message indicative of the detection of the
wide QRS complex is presented using a printer of the external
system.
[0045] In one embodiment, the predetermined threshold QRS width is
pre-stored. In a further embodiment, the pre-stored threshold QRS
threshold is a default value that is changed when another threshold
QRS width is entered by the physician or other caregiver.
[0046] In one embodiment, the detection of the wide QRS complex is
indicated to the physician or other caregiver at a location remote
from the patient. The physician or other caregiver determines the
need to start, stop, or adjust a therapy delivery, such as based on
additional information acquired by the implantable medical device
and transmitted to the remote location through the external system.
In a further embodiment, the external system starts, stops, or
adjusts a therapy delivery based on the information received from
the implantable medical device. In one embodiment, in response to
the detection of the wide QRS complex, the implantable medical
device is programmed to adjust therapy parameters.
[0047] It is to be understood that the above detailed description
is intended to be illustrative, and not restrictive. Other
embodiments, including any possible permutation of the system
components discussed in this document, will be apparent to those of
skill in the art upon reading and understanding 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.
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