Implantable myocardial ischemia detection, indication and action technology

• US 20030013974A1
• Filed: 09/15/2002
• Published: 01/16/2003
• Est. Priority Date: 08/07/1998
• Status: Active Grant

• Current Assignee: Ananth Natarajan, Nitish V. Thakor
• Original Assignee: Ananth Natarajan, Nitish V. Thakor
• Inventors: Thakor, Nitish V., Natarajan, Ananth
• Granted Patent: US 7,277,745 B2
• Time in Patent Office: Days
• US Class Current: 600/481
• CPC Class Codes: A61B 5/287 Holders for multiple electrodes, e.g. electrode catheters for electrophysiological study [EPS]
• CPC Class Codes: A61B 5/349 Detecting specific parameters of the electrocardiograph cycle
• CPC Class Codes: A61B 5/4836 Diagnosis combined with treatment in closed-loop systems or methods A61B5/0036 takes precedence
• CPC Class Codes: A61B 5/726 using Wavelet transforms
• CPC Class Codes: A61M 5/1723 using feedback of body parameters, e.g. blood-sugar, pressure measurement of body parameters A61B5/00
• CPC Class Codes: A61N 1/3627 for treating a mechanical deficiency of the heart, e.g. congestive heart failure or cardiomyopathy
• CPC Class Codes: A61N 1/365 controlled by a physiological parameter, e.g. heart potential evoked response A61N1/371
• CPC Class Codes: A61N 1/37 Monitoring; Protecting
• CPC Class Codes: A61N 1/3962 in combination with another heart therapy

Abstract

One embodiment enables detection of MI/I and emerging infarction in an implantable system. A plurality of devices may be used to gather and interpret data from within the heart, from the heart surface, and/or from the thoracic cavity. The apparatus may further alert the patient and/or communicate the condition to an external device or medical caregiver. Additionally, the implanted apparatus may initiate therapy of MI/I and emerging infarction.

Claims

1. A method comprising:

monitoring the heart for evidence of myocardial ischemia/infarction (MI/I) using a device implanted into a subject;

alerting the subject upon detection of MI/I using a signal generated by the implanted device and transmitted to the subject.

2. A method as in claim 1, wherein the detecting MI/I comprises:

sensing an electrogram signal;

determining the occurrence of MI/I based on the electrogram signal.

3. A method as in claim 1, wherein the detecting MI/I comprises:

positioning a plurality of leads and sensors in the subject;

transmitting data from the sensors to a microprocessor; and

determining whether an MI/I event has occurred.

4. A method as in claim 3, wherein the alerting the subject comprises sending the signal to a device external of the subject.

5. A method as in claim 1, further comprising sending a signal to a device external of the subject.

6. A method as in claim 1, further comprising initiating therapy within the subject after detecting MI/I.

7. A method as in claim 1, further comprising providing a supply of a medicine as part of the device implanted into the subject and supplying a dose of the medicine to the subject after detecting MI/I.

21. A method as in claim 3, wherein the positioning a plurality of leads comprises positioning the leads in an Einthoven triangle placement.

22. A method as in claim 3, wherein the positioning a plurality of leads comprises positioning the leads so that the sensors are configured in an orthogonal pattern.

23. A method as in claim 3, wherein the positioning a plurality of leads comprises placing the leads to form sensing configurations in a plurality of regions in the heart that enhance sensitivity to MI/I.

25. A method as in claim 24, further comprising positioning a plurality of leads in a plurality of heart chambers.

26. A method as in claim 24, further comprising positioning a plurality of leads to provide electrical access to a plurality of chambers of the heart.

27. A method as in claim 24, further comprising positioning routing at least one lead inside a heart cavity selected from the group consisting of the atrial and the ventricular.

28. A method as in claim 24, further comprising positioning at least one lead to provide electrical access to epicardial regions of the heart.

29. A method as in claim 24, further comprising positioning at least one lead to provide electrical access to thoracic regions surrounding the heart.

30. A method as in claim 24, further comprising positioning at least one lead to provide electrical access to subcutaneous regions adjacent in the vicinity of the heart.

31. A method as in claim 24, further comprising positioning multiple electrically conductive sensor elements on at least one lead.

32. A method as in claim 24, further comprising positioning multiple sensor elements selected from the group consisting of unipolar elements and bipolar elements on at least one lead.

33. A method as in claim 24, further comprising mounting at least one sensor element on the container.

34. A method as in claim 24, further comprising:

transmitting at least one signal through at least one of the leads to the circuitry;

amplifying the signal;

filtering the signal; and

converting the signal from an analog signal to a digital signal.

35. A method as in claim 34, wherein a plurality of signals are transmitted through a plurality of leads and are delivered to the circuitry, further comprising feeding the signals to a multiplexer, converting the signal from an analog signal to a digital signal, and delivering the signal to the microprocessor.

36. A method as in claim 1, wherein the detecting myocardial ischemia comprises:

using at least one sensor selected from the group consisting of a cavitary pressure sensor, a myocardial cavitary volume sensor, a blood pO2 sensor, a blood pH sensor, a blood lactate sensor, and a tissue impedance sensor;

wherein the sensor comprises a portion of the device implanted into the subject; and

wherein the sensor is capable of distinguishing a myocardial ischemia condition from a non-myocardial ischemia condition.

37. A method as in claim 36, wherein at least one sensor comprises a myocardial cavitary volume sensor that operates using conductance.

38. A method as in claim 1, wherein the detecting myocardial ischemia includes separating a normal from an ischemic electrogram signal, the method comprising analyzing the electrogram signal using an analysis selected from the group consisting of (1) an electrogram waveform analysis for temporal features, (2) an electrogram waveform analysis using time-domain signal analysis methods, (3) an electrogram waveform analysis using a frequency domain method such as FFT and filtering, and (4) an electrogram waveform analysis using a combined time and frequency analysis method.

39. A method as in claim 38, wherein the analyzing the electrogram signal comprises using an electrogram waveform analysis for at least one temporal feature selected from the group consisting of peaks and inflections.

40. A method as in claim 38, wherein the analyzing the electrogram signal comprises using a frequency domain method selected from the group consisting of fast Fourier transform and filtering.

41. A method as in claim 38, wherein the analyzing the electrogram signal comprises using a combined time and frequency analysis selected from the group consisting of joint time frequency distributions and wavelet analysis.

42. A method as in claim 1, wherein the alerting signal comprises a signal selected from the group consisting of an electrical signal, a magnetic signal, an electromagnetic signal, and an auditory signal.

43. A method as in claim 1, wherein the device comprises a portion of an implanted apparatus selected from the group consisting of a pacemaker, a cardioverter, a defibrillator, a cardiac assist device, and an infusion pump.

53. A method as in claim 24, further comprising a plurality of sensors coupled to the plurality of leads, and detecting the location of a MI/I site by sensing signals from sensors located at different positions within the subject and analyzing the changes in the signal at the different positions.

54. A method as in claim 53, wherein the analyzing comprises calculation of cardiac dipoles of the MI/I site by dipole projection.

55. A method as in claim 53, wherein a plurality of the leads are positioned orthogonal to each other.

56. A method as in claim 53, wherein the detecting the location is determined using leads selected from the group consisting of orthogonal leads, Einthoven triangle leads, chest leads, and endocardial cavitary leads.

58. A method as in claim 57, further comprising detecting MI/I using a plurality of sensors selected from the group consisting of pressure sensors, volume sensors, conductance sensors, impedance sensors, pH sensors, pO2 sensors, temperature sensors, and blood-based biochemical sensors.

60. A method as in claim 59, wherein the pacemaker is positioned at a location selected from the group consisting of atrially, ventrically and dual chambered.

63. A method as in claim 1, wherein the alerting the subject is carried out by electrical stimulation of the subject.

64. A method as in claim 1, wherein the alerting the subject is carried out by a communication selected from the group consisting of auditory communication and vibratory communication.

65. A method as in claim 1, wherein the alerting the subject is carried out using an electromagnetic link to an external device worn by the subject.

66. A method as in claim 1, wherein alerting the subject is carried out by activating a device selected from the group consisting of an external pager and external alarm.

67. A method as in claim 1, further comprising alerting a person other than the subject upon detection of a MI/I using a method selected from the group consisting of electrical communication via RF links, modulation of a magnetic field signal, electromagnetic transmission, auditory transmission, digital encoding and transmission of a signal, and analog modulation and transmission of a signal.

70. A method as in claim 69, wherein a modem protocol is used to communication between the implanted container and a telephone.

74. A method as in claim 69, wherein the device external to the subject comprises a device selected from the group consisting of a telephone and a pager.

8. A method for monitoring the heart of a subject for MI/I inside of the subject, comprising:

implanting into a subject'"'"'s chest a container including circuitry and a microprocessor;

providing a plurality of sensors electrically connected to the circuitry;

positioning at least one sensor in or on the heart of the subject; and

determining whether MI/I has occurred.

9. A method as in claim 8, wherein the plurality of sensors includes at least one sensor from a group consisting of electrical, mechanical and hemodynamic sensors.

10. A method as in claim 9, wherein the microprocessor includes at least one algorithm for interpreting a signal generated by the at least one sensor and determining whether MI/I has occurred.

11. A method as in claim 9, wherein the container is implanted subcutaneaously.

12. A method as in claim 9, wherein the container is implanted with intracavitory connections.

13. A method as in claim 9, wherein the container is implanted with epicardial connections.

14. A method as in claim 9, wherein the container is implanted with electrical access to a plurality of chambers of the heart.

15. A method as in claim 9, wherein the container is fully implanted within the blood vessels and cavity of the heart.

16. A method as in claim 9, wherein the container is implanted with access to intracavitary blood.

17. A method as in claim 9, wherein the container is implanted with access to intravascular blood.

18. A method as in claim 8, wherein at least one sensor is mounted on the container.

19. A method as in claim 8, wherein the sensors are attached to leads extending from the container, the method further comprising positioning leads at three orthogonal locations on the container.

20. A method as in claim 8, wherein the sensors are positioned in a configuration selected from the group consisting of orthogonal, Einthoven triangle, and chest lead configuration.

68. A method as in claim 8, further comprising communicating between the implanted container and a device external to the subject, comprising positioning the external device adjacent to the torso of the subject.

69. A method as in claim 8, further comprising communicating between the implanted container and a device external to the subject.

71. A method as in claim 8, further comprising communicating between the implanted container and a device external to the subject, wherein the communicating is carried out using radiotelemetry.

72. A method as in claim 8, further comprising communicating between the implanted container and a device external to the subject, wherein the communicating is carried out using links between the implanted container and a computer system.

73. A method as in claim 8, further comprising communicating between the implanted container and a device external to the subject, wherein the communicating is carried out using links between the implanted container and a healthcare provider'"'"'s computer system.

75. A method as in claim 8, further comprising communicating between the implanted container and a device external to the subject, wherein the device external to the subject includes an emergency care network.

24. A method for monitoring a heart in a subject for evidence of MI/I comprising:

implanting a container including circuitry and a microprocessor in the subject; and

providing a plurality of leads extending from the container, wherein at least one lead extends to a position inside of the heart.

44. A method for monitoring electrogram signals, comprising sensing changes in depolarization resulting from MI/I.

45. A method as in claim 44, further comprising sensing changes in repolarization resulting from MI/I.

48. A method as in claim 47, wherein determining its temporal features synchronous to the Q, R, S, and T waves includes providing a plurality of leads for delivering signals to a device implanted in the subject, storing an electrogram signal morphology from each lead into a digital memory, and comparing the stored electrogram morphology to the stored electrogram signal.

49. A method as in claim 48, wherein the analyzing includes:

identifying changes in the morphology of depolarization upstroke synchronous with the Q and R waves;

identifying changes in the morphology of depolarization downstroke synchronous with the R and S waves; and

identifying changes in the morphology of repolarization synchronous with the S and T waves.

50. A method as in claim 49, further comprising obtaining the electrogram signal from at least one lead positioned in a location selected from the group consisting of endocardial, pericardial, thoracic cavity, subpectorial and subcutaneous.

51. A method as in claim 50, wherein the analyzing comprises analyzing a unipolar electrogram signal.

52. A method as in claim 50, wherein the analyzing comprises analyzing a bipolar electrogram signal.

46. A method for monitoring electrogram signals, comprising sensing changes in combined depolarization and repolarization and determining whether a MI/I has occurred.

47. A method of detecting a myocardial ischemia signal in a subject, comprising analyzing an electrogram signal by determining its temporal features synchronous to the Q, R, S, and T waves in a surface ECG signal.

57. A method for distinguishing normal and ischemic sensor information comprising analyzing temporal and spectral sensor signals derived from a plurality of sensors implanted in a subject.

59. A method for monitoring a subject for MI/I, wherein a pacemaker is connected to the subject'"'"'s heart, the method comprising:

analyzing a paced electrogram signal;

monitoring MI/I related to changes during a depolarization event in the paced electrogram signal; and

monitoring MI/I related to changes during a repolarization event in the paced electrogram signal.

61. A method for reading, storing and relaying information from an apparatus implanted in a subject, the information being relating to a MI/I event in the subject, the method comprising:

providing a plurality of analog signals relating to the myocardial event to circuitry connected to a analog to digital converter controlled by a microprocessor implanted in a subject;

converting the analog signals to digital data;

storing the digital data in a memory of the microprocessor;

recording the digital data into a continuous loop in the memory and overwriting old data therein;

recovering stored MI/I information; and

transmitting the stored MI/I information to an external device as an electromagnetic code.

62. A method as in claim 61, further comprising displaying the electromagnetic code on the external device and analyzing the displayed electromagnetic code.

76. A method for treating a subject comprising:

implanting a device in the subject;

detecting MI/I using the device;

initiating a therapy in the subject based on a signal generated by the device.

77. A method as in claim 76, wherein the therapy comprises delivering at least one drug selected from the group consisting of bicarbonate, epinephrine, heparin, TPA, streptokinase, and beta blockers.

78. A method as in claim 76, wherein the at least one drug comprises an anti-arrhythmic drug.

79. A method as in claim 76, wherein the device includes at least one drug embedded in a polymer matrix and initiating therapy includes the release of the drug through the polymer matrix.

80. A method as in claim 76, wherein the device includes at least one drug embedded in a portion of the device selected from a lead, a catheter and tubing, and initiating therapy includes releasing a drug from the portion of the device.

81. A method as in claim 76, wherein initiating the therapy includes delivering an electrical shock to the subject.

82. A method as in claim 76, wherein the therapy is initiated immediately after detecting MI/I.

83. A method as in claim 76, wherein the therapy includes treatment that can be carried out by the implanted device.

84. A method as in claim 83, wherein the treatment that can be carried out by the implanted device is initiated immediately after detecting MI/I.

85. A method as in claim 83, wherein the treatment that can be carried out by the implanted device is initiated within one hour after detecting MI/I.

86. A method as in claim 81, wherein the device includes a plurality of leads and positioning the leads at one or more positions selected from the group of intracavitary, epicardial, thoracic, and subcutaneous positions in the subject and therapy includes delivering a shock to the subject through at least one of the leads.

90. A method as in claim 76, wherein detecting MI/I comprises detecting MI/I selected from the group consisting of transient MI/I, permanent MI/I, and recurrent MI/I.

91. A method as in claim 76, wherein detecting MI/I comprises detecting MI/I following an event selected from the group consisting of cardiac arrest, cardioversion, and defibrillation.

92. A method as in claim 76, wherein detecting MI/I comprises detecting MI/I following an event selected from the group consisting of drug infusion and angioplasty therapy.

93. A method as in claim 76, wherein detecting MI/I comprises detecting MI/I in the presence of an event selected from the group of arrhythmia and normal sinus rhythm.

87. A method of manufacturing an implantable device elected from the group consisting of pacemakers, cardio-defibrillators, atrial defibrillators, ventrical defibrillators, cardiac assist devices, and drug infusion devices, the method including the steps of incorporating circuitry for monitoring the occurrence of a MI/I in a subject and providing a signal indicating the occurrence of a MI/I.

88. A method as in claim 87, further comprising delivering the signal to a device external to the implantable device.

89. A method as in claim 87, further comprising alerting the subject of the occurrence of a MI/I.

94. An apparatus for detecting MI/I in a subject, comprising:

an implantable container;

at least one lead adapted for insertion into the heart;

at least one sensor adapted for insertion into the heart; and

a microprocessor in the container to analyze data from the at least one sensor.

95. An apparatus as in claim 94, further comprising circuitry to transmit a signal from the sensor to the microprocessor.

96. An apparatus as in claim 95, further comprising means to alert the subject after detecting MI/I.

97. An apparatus as in claim 95, further comprising means to communicate with at least one device external to the subject.

98. An apparatus as in claim 94, further comprising means for initiating therapy after detecting MI/I.

99. An apparatus as in claim 95, further comprising a supply of at least one drug adapted for insertion into the body, wherein the supply is released upon receiving a signal from the microprocessor.

100. An apparatus as in claim 94, wherein the container comprises a can that is adapted to fit inside of the subject'"'"'s heart.

101. An apparatus as in claim 94, wherein the container comprises a can comprising the shape of an implanted device selected from the group consisting of a pacemaker, a cardioverter, a defibrillator, a cardiac assist device, and an infusion pump.

102. An apparatus as in claim 94, wherein the container comprises a can having a triangular shape.

103. An apparatus as in claim 94, wherein the container comprises a can shaped in the form of a pouch adapted to surround a portion of a heart.

104. An apparatus as in claim 94, wherein the container comprises a can shaped to include three orthogonal locations for mounting electrodes.

105. An apparatus as in claim 94, wherein the container comprises a can shaped to include locations to permit Einthoven triangle electrode placement.

106. An apparatus as in claim 94, wherein the container comprises a can, wherein at least one sensor is mounted on the can.

107. An apparatus as in claim 94, further comprising an electrode, wherein the sensor is attached to the lead through the electrode.

108. An apparatus as in claim 94, wherein the sensor includes an electrode coupled to the lead.

109. An apparatus as in claim 108, comprising a plurality of electrodes adapted for insertion into the heart in a variety of locations.

110. An apparatus as in claim 94, wherein the lead is configured to transmit electrogram signals from at least two locations selected from the group consisting of atrial heart cavity locations, ventricular heart cavity locations, epicardial heart locations, thoracic locations surrounding a heart, and subcutaneous locations adjacent to a heart.

111. An apparatus as in claim 94, wherein at least one lead includes a plurality of sensors coupled thereto.

112. An apparatus as in claim 94, wherein at least one lead includes a plurality of electrically conductive sensor elements thereon.

113. An apparatus as in claim 94, wherein at least one lead includes multiple unipolar elements.

114. An apparatus as in claim 94, wherein at least one lead includes multiple bipolar elements.

115. An apparatus as in claim 94, wherein the container acts as a reference for electrical common.

116. An apparatus as in claim 94, wherein at least one sensor is mounted on the container and at least one sensor is mounted to a lead a distance away from the container.

118. An apparatus as in claim 117, wherein the logic device comprises a microprocessor.

119. An apparatus as in claim 117, further comprising at least one amplifier disposed within the container.

120. An apparatus as in claim 119, further comprising at least one filter disposed within the container.

121. An apparatus as in claim 117, further comprising at least one sensor to recognize a MI/I condition, the sensor being coupled to a lead.

122. An apparatus as in claim 121, wherein the sensor comprises a sensor selected from the group consisting of a blood pO₂ sensor, a blood pH sensor, a blood lactate sensor, a blood temperature sensor, and a tissue impedance sensor.

123. An apparatus as in claim 117, wherein the monitoring for MI/I includes separating normal from ischemic electrogram signals by means to perform electrogram waveform analysis for temporal features including peaks and inflections.

124. An apparatus as in claim 117, wherein the monitoring for MI/I includes separating normal from ischemic electrogram signals by means to perform electrogram waveform analysis using time-domain signal analysis.

125. An apparatus as in claim 117, wherein the monitoring for MI/I includes separating normal from ischemic electrogram signals by means to perform electrogram waveform analysis using frequency domain methods.

126. An apparatus as in claim 117, wherein the monitoring for MI/I includes separating normal from ischemic electrogram signals by means to perform electrogram waveform analysis using combined time and frequency analysis.

127. An apparatus as in claim 117, wherein the monitoring for MI/I includes separating normal from ischemic electrogram signals by means to analyze changes in depolarization and repolarization.

128. An apparatus as in claim 117, wherein the monitoring for MI/I includes means for detecting a MI/I signal by determining its temporal features synchronous to the Q, R, S, and T waves in an electrogram signal.

130. An apparatus as in claim 129, further comprising means for determining the location using dipole projection.

132. An apparatus as in claim 131, further comprising an external source and means for receiving the transmitted signal by the external source.

135. An apparatus as in claim 134, wherein the transmitter comprises a device selected from the group consisting of an RF transmitter, an electrical transmitter, and an electromagnetic transmitter.

136. An apparatus as in claim 134, wherein the transmitter comprises means to transmit a signal to the subject.

137. An apparatus as in claim 136, wherein the transmitter comprises means to transmit a signal to a device external from the subject.

139. An apparatus as in claim 138, wherein the supply comprises at least one drug selected from the group consisting of bicarbonate, epinephrine, heparin, TPA, streptokinase, and beta blockers.

140. An apparatus as in claim 138, wherein at least a portion of the supply is housed in a polymeric matrix.

141. An apparatus as in claim 139, wherein at least a portion of the supply is housed in a structure selected from the group consisting of a lead, an indwelling catheter, and tubing.

143. An apparatus as in claim 142, wherein the means comprises means for delivering an electric shock to the subject.

144. An apparatus as in claim 142, wherein the means comprises means for controlling the delivery of one or more drugs to the user.

146. An apparatus as in claim 145, further comprising a structure selected from the group consisting of a pacemaker, a cardioverter-defibrillator, an atrial defibrillator, a cardiac assist device, and a drug infusion device.

147. An apparatus as in claim 134, wherein the implantable container is adapted to fit within a heart cavity.

148. An apparatus as in claim 134, wherein the implantable container is adapted to fit transvenously within a subject.

117. An implantable apparatus for monitoring a subject for MI/I comprising:

a hermetically sealed container;

circuitry disposed within the container;

an analog to digital converter disposed within the container;

a logic device disposed within the container; and

a feed-through interface between at least one lead extending from the container and the circuitry.

129. An apparatus for determining the location of a myocardial ischemic event comprising an implantable device including a plurality of sensors adapted to be positioned in various locations in and on the heart, the device further including means for analyzing the changes in electrogram signals received from the sensors.

131. An apparatus for recording and storing MI/I information, comprising:

an implantable device comprising;

means for digitizing electrogram signals

means for storing the signals;

means for recording the digitized electrogram signals in memory;

means for recovering the digitized electrogram signals in memory; and

means for transmitting a signal from the apparatus to an external source.

133. An apparatus for detecting MI/I in a subject, comprising:

means for detecting MI/I; and

means for generating a signal to alert the subject about the MI/I;

wherein the means for detecting and the means for generating the signal are implanted in the subject.

134. An apparatus for detecting MI/I in a subject, comprising:

an implantable container;

at least one lead adapted for insertion into the heart and electrically connected to circuitry in the container;

at least one sensor coupled to the at least one lead and adapted for insertion into the heart;

a microprocessor in the container to analyze data from the at least one sensor; and

a transmitter.

138. An implantable apparatus for detecting and treating MI/I in a subject, comprising:

a container;

at least one lead adapted for insertion in the user and electrically connected to circuitry in the container;

at least one sensor coupled to the at least one lead;

a logic device in the container to analyze data from the at least one sensor; and

a supply of at least one drug to treat MI/I.

142. An implantable apparatus for detecting and treating MI/I in a subject, comprising:

a container;

a plurality of leads electrically connected to circuitry in the container;

a plurality of sensors coupled to the plurality of leads;

a logic device in the container to analyze data from the plurality of leads; and

means for treating the subject in response to a determination that a MI/I has occurred.

145. An implantable apparatus for detecting and treating MI/I in a subject, comprising:

a plurality of sensors coupled to the plurality of leads, wherein at least one sensor is adapted for placement in or on the subject'"'"'s heart; and

a logic device to analyze data from the plurality of leads and determine if a MI/I has occurred.