Source: http://www.google.com/patents/US6314319?ie=ISO-8859-1&dq=U.S.+Patent+No.+4,528,643
Timestamp: 2014-07-10 11:34:54
Document Index: 146345906

Matched Legal Cases: ['art. 38', 'art.\n40', 'art.\n45', 'art. 48', 'art. 90', 'art.\n92', 'art.\n97', 'art. 101']

Patent US6314319 - Method and apparatus for temporarily electrically forcing cardiac output in ... - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign in<nobr>Advanced Patent Search</nobr>PatentsAn electrical method and apparatus for stimulating cardiac cells causing contraction to force hemodynamic output during fibrillation, hemodynamically compromising tachycardia, or asystole. Forcing fields are applied to the heart to give cardiac output on an emergency basis until the arrhythmia ceases...http://www.google.com/patents/US6314319?utm_source=gb-gplus-sharePatent US6314319 - Method and apparatus for temporarily electrically forcing cardiac output in a tachyarrhythmia patientAdvanced Patent SearchPublication numberUS6314319 B1Publication typeGrantApplication numberUS 09/251,553Publication dateNov 6, 2001Filing dateFeb 17, 1999Priority dateMay 31, 1994Fee statusPaidAlso published asUS5735876, US5978703, US6567697Publication number09251553, 251553, US 6314319 B1, US 6314319B1, US-B1-6314319, US6314319 B1, US6314319B1InventorsKai Kroll, Mark W. KrollOriginal AssigneeGalvani, Ltd.Export CitationBiBTeX, EndNote, RefManPatent Citations (1), Referenced by (12), Classifications (12), Legal Events (7) External Links: USPTO, USPTO Assignment, EspacenetMethod and apparatus for temporarily electrically forcing cardiac output in a tachyarrhythmia patientUS 6314319 B1Abstract An electrical method and apparatus for stimulating cardiac cells causing contraction to force hemodynamic output during fibrillation, hemodynamically compromising tachycardia, or asystole. Forcing fields are applied to the heart to give cardiac output on an emergency basis until the arrhythmia ceases or other intervention takes place. The device is used as a stand alone external or internal device, or as a backup to an ICD, atrial defibrillator, or an anti-tachycardia pacemaker. The method and apparatus maintain some cardiac output and not necessarily defibrillation.
We claim: 1. A method for forcing cardiac output during tachyarrhythmia in a patient, comprising the steps of:
(a) attaching a plurality of electrodes to external portions of a patient's body proximate the patient's thoracic region so that the electrodes may deliver electrical pulses which will be transmitted through portions of the patient's upper body; (b) providing means for detecting the presence of tachyarrhythmia in the patient; (c) detecting the presence of tachyarrhythmia in the patient; (d) delivering electrical current pulses through the patient's body, via said electrodes after detecting tachyarrhythmia, at a rate between about 60 and 200 pulses per minute, said electrical current pulses having a voltage less than a normal defibrillation voltage level, to force contraction in the patient's heart and facilitate a minimum level of cardiac output until cessation of the tachyarrhythmia or until other medical intervention is provided; and (e) delivering further medical intervention if the desired minimum level of cardiac output has not occurred, said medical intervention comprising delivering at lease one external defibrillation pulse to the patient following a plurality of said electrical current pulses. 2. The method of claim 1, further comprising the steps of reassessing the presence of an arrhythmia at predetermined intervals and terminating said delivery of electrical current pulses or defibrillation pulses if the arrhythmia is no longer present.
3. The method of claim 1, in which each electrical current pulse has an energy of less than about 360 joules.
7. The method of claim 1, wherein said step of delivering electrical current pulses is repeated for at least thirty minutes to maintain some cardiac output.
8. The method of claim 1, wherein the step of delivering electrical current pulses comprises delivery of a plurality of pulses which are greater than about 250 mA.
9. The method of claim 1, wherein said step of delivering electrical current pulses is performed immediately after detecting tachyarrythmia.
10. A method for producing minimal cardiac output on an emergency basis in a patient experiencing arrhythmia, comprising the steps of:
(a) attaching a plurality of electrodes to external portions of a patient's chest so that the electrodes may deliver electrical pulses which will be transmitted through portions of the patient's upper body; (b) providing means for detecting the presence of arrhythmia in the patient; (c) detecting the presence of arrhythmia in the patient; (d) delivering a defibrillation pulse to an external portion of the patient's body; and (e) delivering electrical current pulses through the patient's body, via said electrodes after said defibrillation pulse delivery and after detecting arrhythmia, at a rate between about 60 and 200 pulses per minute, said electrical current pulses having a voltage greater than that which would only pace the heart and less than that which would defibrillate the patient's heart, so as to force some contraction in the patient's heart, whereby a minimum level of cardiac output is maintained until cessation of the arrhythmia or until other medical intervention is provided. 11. The method of claim 10, in which the power supply means provides electrical current pulses through the electrodes in a voltage range of greater than about 25 volts and less than about 2000 volts.
12. The method of claim 10, in which the arrythmia includes either tachycardia or bradycardia.
13. The method of claim 10, further comprising the step of electronically interfacing said means for detecting the presence of arrythmia in the patient with said other medical intervention.
14. The method of claim 10, wherein the step of delivering electrical current pulses comprises delivery of a plurality of pulses which are greater than about 250 mA.
15. A system, for external use on a human body, for maintaining some cardiac output of a patient's heart during arrhythmia using electrical forcing fields, comprising:
(a) power supply means; (b) arrhythmia detection means connected to said power supply means; (c) pulse delivery means connected to said power supply means for delivering multiple electrical current pulses through portions of the patient's upper body; (d) output control means connected to said arrhythmia detection means, said power supply means, and said pulse delivery means for controlling the delivery of multiple electrical current pulses to the patient's upper body after the detection of arrhythmia, said electrical current pulses having a voltage greater than about 25 volts and less than the voltage necessary to defibrillate the patient, said output control means providing pulses suitable for only producing contraction in the patient's heart sufficient to maintain a level of cardiac output which is a fraction of the normal maximum cardiac output until cessation of the arrhythmia or until other medical intervention is provided; and (e) external defibrillation means cooperating with said output control means and adapted for delivering at least one external defibrillation pulse to the patient's body when said contraction in the patient's heart is not sufficient to maintain a desired level of cardiac output and when said pulse delivery means is not delivering said electrical current pulses. 16. The system of claim 15, in which said electrical current pulses are delivered at a rate between about 60 and 200 beats per minute.
17. The system of claim 15, further comprising cardiac output sensing means.
18. The system of claim 15, further comprising cardiac pressure sensing means.
19. The system of claim 15, further comprising blood pressure monitoring means connected to said arrhythmia detection means.
20. The system of claim 15, further comprising doppler sensing means for monitoring cardiac output, said doppler sensing means functionally operable with said arrhythmia detection means.
21. The system of claim 15, in which said blood pressure monitoring means monitors cardiac output and further comprises means for adjusting said electrical current pulse amplitude by said output control means to maintain an optimum therapy for maintaining cardiac output.
22. The system of claim 15, wherein a plurality of said electrical current pulses have rounded edges.
23. The system of claim 15, further comprising the step of providing means for forming a plurality of said electrical current pulses as a train of at least 10 narrow pulses.
24. The system of claim 15, in which said arrythmia detection means comprises means for reassessing the presence of arrhythmia at predetermined intervals and stopping said electrical current pulses with said output control means if the arrhythmia is no longer present.
25. The system of claim 15, in which said arrythmia detection means comprises means for reassessing the presence of arrhythmia and cardiac output at predetermined intervals and adjusting said electrical current pulses with said output control means according to said reassessment.
26. The system of claim 15, in which said power supply means and said output control means deliver said electrical current pulses at a level to maintain cardiac output for at least about 30 minutes.
27. The system of claim 15, wherein said output control means comprises means for delivering said electrical current pulses for at least one hour to maintain cardiac output.
28. The system of claim 15, in which additional heart treatment devices are used in combination therewith including means to perform conventional anti-tachycardia pacing, means to perform tachycardia cardioversion, or means to perform various forms of defibrillation.
29. The system of claim 15, in which the power supply means, the output control means, and the arrhythmia detection means operate to produce a cardiac output of between about 10% and about 90% of the normal maximum cardiac output for the patient.
30. The system of claim 15, in which the power supply means, the output control means, and the arrhythmia detection means operate to produce a cardiac output of between about 20% and about 80% of the normal maximum cardiac output for the patient.
31. The system of claim 15, in which the power supply means, the output control means, and the arrhythmia detection means operate to produce a cardiac output of greater than about 30% of the normal maximum cardiac output for the patient.
32. The system of claim 15, wherein the electrical current pulses are greater than about 250 mA.
33. A device, for external attachment to a human body, for maintaining some cardiac output of a patient's heart during dysrhythmia using electrical forcing fields, comprising:
(a) power supply means for providing power to pulse delivery means, arrythmia detection means, and output control means; (b) arrhythmia detection means operatively connected to said power supply means; (c) first pulse delivery means operatively connected to said power supply means for delivering multiple electrical current pulses through portions of the patient's upper body, said multiple electrical pulses comprising cardiac therapy responsive to the particular patient's cardiac rhythm; (d) output control means operatively connected to said arrhythmia detection means, said power supply means, and said first pulse delivery means for controlling the delivery of multiple electrical current pulses to the human heart after the detection of arrhythmia; said electrical current pulses having an amplitude suitable for delivery through the patient's upper body and for contributing to the mechanical and electrical mechanisms adequate to produce contractions in the patient's heart and to cause only a fraction of the normal maximum cardiac output but enough cardiac output to maintain cardiac viability until cessation of the dysrhythmia or until other medical intervention is provided; and (e) second pulse delivery means operably interfaced with at least said output control means for delivering at least one external defibrillation pulse to the patient's body when further medical intervention is required. 34. The device of claim 33 in which the amplitude of the electrical current pulses is greater than a cardiac pacing level of about 20 volts and less than a normal cardiac defibrillating voltage of about 2000 volts.
35. The device of claim 33, in which said electrical current pulses comprise pulses which are greater than about 140 mA.
36. The device of claim 33, in which said electrical current pulses comprise pulses which are less than about 20 ms.
37. A method for providing hemodynamic output of a heart during arrythmia, comprising the steps of:
(a) attaching a plurality of electrodes to external portions of a patient's body proximate the patient's chest so that the electrodes may deliver or receive electrical pulses transmitted through portions of the patient's upper body; (b) providing means for detecting the presence of arrhythmia in the patient; (c) detecting the presence of arrhythmia in the patient; (d) delivering a first series of electrical current pulses for a first period of time, through the patient's body, via said electrodes after detecting arrhythmia; said electrical current pulses having a voltage less than a normal defibrillation voltage level but enough to force hemodynamic activity by mechanical and electrical responses of the patient's body to facilitate contraction of the patient's heart and to facilitate a minimum level of cardiac output; (e) determining the output status of the heart; (f) if the output status of the heart requires, then delivering at least one electrical defibrillation pulse having a voltage level sufficient to defibrillate the patient's heart; and (g) determining the output status of the heart. 38. The method of claim 37, in which the step of determining the output status of the heart comprises detecting whether arrythmia still exists.
39. The method of claim 37, in which the step of determining the output status of the heart comprises detecting whether there is an abnormal low pressure within the heart.
40. The method of claim 37, further comprising the step of delivering at least one further series of electrical current pulses, after delivering said first electrical defibrillation pulse, and after determining the output status of the heart, and if said determination indicates a continued existence of arrythmia or the presence of a low pressure in the heart indicative of inadequate cardiac output.
41. The method of claim 37, in which the electrical current pulses are timed to coincide with the natural pumping of the patient's atria.
42. The method of claim 37, in which said step of determining the output status of the heart comprises initiation by said output control means of an adjustment of the characteristics of said electrical current pulses according to said determined output status.
43. A method for providing hemodynamic output of a heart during arrythmia, comprising the steps of:
(a) attaching a plurality of electrodes to external portions of a patient's body proximate the patient's chest so that the electrodes may deliver or receive electrical pulses transmitted through portions of the patient's upper body; (b) providing means for detecting the presence of arrhythmia in the patient; (c) detecting the presence of arrhythmia or low cardiac output in the patient; (d) delivering a first series of electrical current pulses for a first period of time, through a portion of the patient's body, via electrodes after detecting said arrhythmia, said first series of electrical current pulses comprising at least one electrical current pulse having a voltage level suitable for defibrillating the patient's heart; (e) delivering a second series of electrical current pulses for a first period of time, through a portion of the patient's body, via said electrodes after detecting arrhythmia; said second series of electrical current pulses comprising a plurality of pulses having a voltage level less than a normal defibrillation voltage level but enough to force hemodynamic activity by contraction of the patient's heart and to facilitate a minimum level of cardiac output. 44. The method of claim 43 further comprising the step of determining the output status of the heart.
45. The method of claim 43 in which the arrythmia is of an asystole type relating to absence of cardiac contraction and leading to cardiac arrest.
46. The method of claim 43, in which the pulse widths of said second series pulses are between about 1 ms and about 50 ms.
47. A method for conducting emergency electrical cardiac output in a human, comprising the steps of:
(a) attaching a plurality of electrodes to external portions of a patient's body so that the electrodes may deliver electrical pulses which will be transmitted through portions of the patient's upper body; (b) providing means for detecting the presence of arrhythmia in the patient; (c) detecting the presence of arrhythmia in the patient; (d) delivering electrical current pulses through the patient's body to the patient's heart, via said electrodes after detecting arrhythmia, at a voltage level of less than a defibrillating voltage level, to force contraction in the patient's heart and to facilitate a minimum level of cardiac output until cessation of the arrhythmia or until other medical intervention is provided; and (e) providing further medical intervention by delivering a series of defibrillation pulses through the patient's body, said series comprising at least one electrical current pulse having a voltage level sufficient to defibrillate the patient's heart. 48. The method of claim 47 in which the electrical current pulses are delivered at a rate of less than about 200 pulses per minute.
49. A method for forcing cardiac output during tachyarrhythmia in a patient, comprising the steps of:
(a) positioning a plurality of electrodes proximate portions of a patient's heart so that the electrodes may deliver electrical pulses which will be transmitted through the patient's heart; (b) providing means for detecting the presence of tachyarrhythmia in the patient; (c) detecting the presence of tachyarrhythmia in the patient; (d) delivering electrical current pulses through the patient's heart, via said electrodes after detecting tachyarrhythmia, said electrical current pulses having a voltage less than a normal defibrillation voltage level, to force contraction in the patient's heart and to facilitate a minimum level of cardiac output until cessation of the tachyarrhythmia or until other medical intervention is provided; and (e) delivering further medical intervention if the desired minimum level of cardiac output has not occurred, said medical intervention comprising delivering at lease one defibrillation pulse to the patient following a plurality of said electrical current pulses. 50. The method of claim 49, further comprising the steps of reassessing the presence of an arrhythmia at predetermined intervals and terminating said delivery of electrical current pulses or defibrillation pulses if the arrhythmia is no longer present.
51. The method of claim 49, in which each electrical current pulse has an energy of less than about 360 joules.
52. The method of claim 49, further comprising the steps of monitoring cardiac output and adjusting said electrical current pulse with respect to amplitude to maintain a predetermined level of cardiac output, thereby conserving electrical energy.
53. The method of claim 49, wherein a plurality of said electrical current pulses have rounded edges.
54. The method of claim 49, further comprising the step of forming a plurality of said electrical current pulses as a train of at least about 10 narrow pulses.
55. The method of claim 49, wherein said step of delivering electrical current pulses is repeated for at least thirty minutes to maintain some cardiac output.
56. The method of claim 49, wherein the step of delivering electrical current pulses comprises delivery of a plurality of pulses which are greater than about 250 mA.
57. The method of claim 49, wherein said step of delivering electrical current pulses is performed immediately after detecting tachyarrythmia.
58. The method of claim 49, wherein said defibrillation pulse is delivered to the patient internally.
59. A method for producing minimal cardiac output on an emergency basis in a patient experiencing arrhythmia, comprising the steps of:
(a) positioning a plurality of electrodes to enable delivery of electrical pulses which will be transmitted through portions of the patient's upper body; (b) providing means for detecting the presence of arrhythmia in the patient; (c) detecting the presence of arrhythmia in the patient; (d) delivering a defibrillation pulse within the patient's body; and (e) delivering electrical current pulses through the patient's body, via said electrodes after said defibrillation pulse delivery and after detecting arrhythmia, said electrical current pulses having a voltage greater than that which would only pace the heart and less than that which would defibrillate the patient's heart, so as to force some contraction in the patient's heart, whereby a minimum level of cardiac output is maintained until cessation of the arrhythmia or until other medical intervention is provided. 60. The method of claim 59, in which the power supply means provides electrical current pulses through the electrodes in a voltage range of greater than about 25 volts and less than about 2000 volts.
61. The method of claim 59, in which the arrythmia includes either tachycardia, asystole, or bradycardia.
62. The method of claim 59, further comprising the step of electronically interfacing said means for detecting the presence of arrythmia in the patient with said other medical intervention.
63. The method of claim 59, wherein the step of delivering electrical current pulses comprises delivery of a plurality of pulses which are greater than about 250 mA.
64. An at least partially implantable system, for internal use on a human body, for maintaining some cardiac output of a patient's heart during arrhythmia using electrical forcing fields, comprising:
(a) power supply means; (b) arrhythmia detection means connected to said power supply means; (c) pulse delivery means connected to said power supply means for delivering multiple electrical current pulses through portions of the patient's upper body; (d) output control means connected to said arrhythmia detection means, said power supply means, and said pulse delivery means for controlling the delivery of multiple electrical current pulses to the patient's upper body after the detection of arrhythmia, said electrical current pulses having a voltage level less than the voltage necessary to defibrillate the patient, said output control means providing pulses suitable for only producing contraction in the patient's heart sufficient to maintain a level of cardiac output which is a fraction of the normal maximum cardiac output until cessation of the arrhythmia or until other medical intervention is provided; and (e) internal defibrillation means cooperating with said output control means and adapted for delivering at least one internal defibrillation pulse to the patient's body when said contraction in the patient's heart is not sufficient to maintain a desired level of cardiac output and when said pulse delivery means is not delivering said electrical current pulses. 65. The system of claim 64, in which said electrical current pulses are delivered at a rate between about 60 and 200 beats per minute.
66. The system of claim 64, further comprising cardiac output sensing means.
67. The system of claim 64, further comprising cardiac pressure sensing means.
68. The system of claim 64, further comprising blood pressure monitoring means connected to said arrhythmia detection means.
69. The system of claim 64, further comprising doppler sensing means for monitoring cardiac output, said doppler sensing means functionally operable with said arrhythmia detection means.
70. The system of claim 64, in which said blood pressure monitoring means monitors cardiac output and further comprises means for adjusting said electrical current pulse amplitude by said output control means to maintain an optimum therapy for maintaining cardiac output.
71. The system of claim 64, wherein a plurality of said electrical current pulses have rounded edges.
72. The system of claim 64, further comprising the step of providing means for forming a plurality of said electrical current pulses as a train of at least 10 narrow pulses.
73. The system of claim 64, in which said arrythmia detection means comprises means for reassessing the presence of arrhythmia at predetermined intervals and stopping said electrical current pulses with said output control means if the arrhythmia is no longer present.
74. The system of claim 64, in which said arrythmia detection means comprises means for reassessing the presence of arrhythmia and cardiac output at predetermined intervals and adjusting said electrical current pulses with said output control means according to said reassessment.
75. The system of claim 64, in which said power supply means and said output control means deliver said electrical current pulses at a level to maintain cardiac output for at least about 30 minutes.
76. The system of claim 64, wherein said output control means comprises means for delivering said electrical current pulses for at least one hour to maintain cardiac output.
77. The system of claim 64, in which the power supply means, the output control means, and the arrhythmia detection means operate to produce a cardiac output of between about 10% and about 90% of the normal maximum cardiac output for the patient.
78. The system of claim 64, in which the power supply means, the output control means, and the arrhythmia detection means operate to produce a cardiac output of between about 20% and about 80% of the normal maximum cardiac output for the patient.
79. The system of claim 64, in which the power supply means, the output control means, and the arrhythmia detection means operate to produce a cardiac output of greater than about 30% of the normal maximum cardiac output for the patient.
80. The system of claim 64, wherein the electrical current pulses are greater than about 250 mA.
81. An implantable device for maintaining some cardiac output of a patient's heart during dysrhythmia using electrical forcing fields, comprising:
(a) power supply means for providing power to pulse delivery means, arrythmia detection means, and output control means; (b) arrhythmia detection means operatively connected to said power supply means; (c) first pulse delivery means operatively connected to said power supply means for delivering multiple electrical current pulses through portions of the patient's upper body, said multiple electrical pulses comprising cardiac therapy responsive to the particular patient's cardiac rhythm; (d) output control means operatively connected to said arrhythmia detection means, said power supply means, and said first pulse delivery means for controlling the delivery of multiple electrical current pulses to the human heart after the detection of arrhythmia; said electrical current pulses having an amplitude suitable for delivery through portions of the patient's upper body and for contributing to the mechanisms that produce contractions in the patient's heart which to cause only a fraction of the normal maximum cardiac output but enough cardiac output to maintain cardiac viability until cessation of the dysrhythmia or until other medical intervention is provided; and (e) second pulse delivery means operably interfaced with at least said output control means for delivering at least one defibrillation pulse to the patient's body when further medical intervention is required. 82. The device of claim 81 in which the amplitude of the electrical current pulses is greater than a cardiac pacing level of about 20 volts and less than a cardiac defibrillating voltage.
83. The device of claim 81 in which the voltage is less than about 2000 volts.
84. The device of claim 81 in which the voltage is less than about 1000 volts.
85. The device of claim 81 in which the voltage is less than about 500 volts.
86. The device of claim 81, in which said electrical current pulses comprise pulses which are greater than about 140 mA.
87. The device of claim 81, in which said electrical current pulses comprise pulses which are less than about 20 ms.
88. The device of claim 81 in which said second pulse delivery means is an implantable cardioverter defibrillator.
89. A method for providing hemodynamic output of a heart during arrythmia, comprising the steps of:
(a) positioning a plurality of electrodes in a patient's body proximate the patient's heart so that the electrodes may deliver or receive electrical pulses transmitted through portions of the patient's upper body and heart; (b) providing means for detecting the presence of arrhythmia in the patient; (c) detecting the presence of arrhythmia in the patient; (d) delivering a first series of electrical current pulses for a first period of time via said electrodes after detecting arrhythmia; said electrical current pulses having a voltage less than a normal defibrillation voltage level but enough to force hemodynamic activity by mechanical and electrical responses of the patient's body to facilitate contraction of the patient's heart and to facilitate a minimum level of cardiac output; (e) determining the output status of the heart; (f) if the output status of the heart requires, then delivering at least one electrical defibrillation pulse having a voltage level sufficient to defibrillate the patient's heart; and (g) determining the output status of the heart. 90. The method of claim 89, in which the step of determining the output status of the heart comprises detecting whether arrythmia still exists.
91. The method of claim 89, in which the step of determining the output status of the heart comprises detecting whether there is an abnormal low pressure within the heart.
92. The method of claim 90, further comprising the step of delivering at least one further series of electrical current pulses, after delivering said first electrical defibrillation pulse, and after determining the output status of the heart, and if said determination indicates a continued existence of arrythmia or the presence of a low pressure in the heart indicative of inadequate cardiac output.
93. The method of claim 91, in which the electrical current pulses are timed to coincide with the natural pumping of the patient's atria.
94. The method of claim 92, in which said step of determining the output status of the heart comprises initiation by said output control means of an adjustment of the characteristics of said electrical current pulses according to said determined output status.
95. A method for providing hemodynamic output of a heart during arrythmia, comprising the steps of:
(a) positioning a plurality of electrodes within portions of a patient's body proximate the patient's heart for delivery or receipt of electrical pulses transmitted through portions of the patient's upper body and heart; (b) providing means for detecting the presence of arrhythmia in the patient; (c) detecting the presence of arrhythmia or low cardiac output in the patient; (d) delivering a first series of electrical current pulses for a first period of time, through the patient's heart, via electrodes after detecting said arrhythmia, said first series of electrical current pulses comprising at least one electrical current pulse having a voltage level suitable for defibrillating the patient's heart; and (e) delivering a second series of electrical current pulses for a first period of time, through a portion of the patient's upper body and heart, via said electrodes after detecting arrhythmia; said second series of electrical current pulses comprising a plurality of pulses having a voltage level less than a normal defibrillation voltage level but enough to force hemodynamic activity by contraction of the patient's heart and to facilitate a minimum level of cardiac output. 96. The method of claim 95 further comprising the step of determining the output status of the heart.
97. The method of claim 95 in which the arrythmia is of an asystole type relating to absence of cardiac contraction and leading to cardiac arrest.
98. The method of claim 95, in which the pulse widths of said second series pulses are between about 1 ms and about 50 ms.
99. The method of claim 95, in which the pulse widths of said second series pulses are greater than about 1 ms and less than about 20 ms.
100. A method for conducting emergency electrical cardiac output in a human, comprising the steps of:
(a) providing means for detecting the presence of arrhythmia in the patient; (b) detecting the presence of arrhythmia in the patient; (c) delivering electrical current pulses through the patient's body to the patient's heart via electrodes, after detecting arrhythmia, at a voltage level of less than a defibrillating voltage level, to force contraction in the patient's heart and to facilitate a minimum level of cardiac output until cessation of the arrhythmia or until other medical intervention is provided; and (d) providing further medical intervention by delivering a series of defibrillation pulses through the patient's body, said series comprising at least one electrical current pulse having a voltage level sufficient to defibrillate the patient's heart. 101. The method of claim 100 in which the electrical current pulses are delivered ata rate of less than about 200 pulses per minute.
This application is a continuation of Ser. No. 08/754,712 filed Dec. 6, 1996, now U.S. Pat. No. 5,978,703 which is a continuation of Ser. No. 08/543,001 filed Oct. 13, 1995, now abandoned, which is a continuation of Ser. No. 08/251,349 filed May 31, 1994, now abandoned.
SUMMARY OF THE INVENTION The invention provides an electrical method of stimulating cardiac cells causing contraction to force hemodynamic output during fibrillation, hemodynamically compromising tachycardia, or asystole. Forcing fields are applied to the heart to give cardiac output on an emergency basis until the arrhythmia ceases or other intervention takes place. The device is usable as a stand alone external or internal device or as a backup to an ICD, atrial defibrillator, or an anti-tachycardia pacemaker.
Implantable batteries are also limited to a certain power output and energy storage. If an output pulse is 50 V and the electrode impedance is 50 Ω, the power during the pulse is P=V2/R=50 V*50 V/50 Ω=50 W. If the pulse has a duration of 2 ms then the energy per pulse is 0.1 J. If two pulses are delivered every second, the charger must be capable of delivering 0.2 J per second which is 200 mW. This is well within the limits of an implantable battery. An implantable battery can typically deliver 5 W of power. However, 200 V pulses at 3 per second would require 4.8 W which is near the limit of the battery and charging circuitry. A typical implantable battery energy capacity is 10,000 J. Delivering forcing pulses at a rate of 4.8 W would deplete the battery in only 35 minutes (10,000 J/4.8 W=2083 seconds). Thirty five minutes may not be enough time to transport the patient to a hospital. Therefore 200 V represents the highest practical voltage for continuous operation in an implantable embodiment, although voltages of up to 350 V could be used for short periods and adjusted down when hemodynamic output is verified. A practical lower limit is about 10 V. During normal sinus rhythm, 10 V delivered through the patches would pace. However, during fibrillation the 10 V could not pace and only cells very near the electrodes would be captured. This would be insufficient for forcing cardiac output.
For an external ECOF the calculations are similar, but scaled up. The typical ECOF pulse would have a voltage of 100 V with a range of 25-500 V. With electrode impedances of 50 Ω the power during the pulse is P=V2/R=100 V*100 V/50 Ω=200 W with a range of 12.5-5,000 W. If the pulse has a duration of 2-5 ms, then the energy per pulse is 0.02-25 J. This is much less than the American Heart Association recommended output of 360 J for an external defibrillator.
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