Patent EA-003443-B1 (EA)
Title: Antitachycardial pacing
Inventor: MOWER M D MORTON M
IPC: A61N1/362
Filed: 2000-01-14
Abstract: 1. A method of operating as implantable cardioverter-defibrillator (ICD), the ICD having output means for delivering electrical stimulation of a predetermined polarity, amplitude, shape and duration, the method comprising: sensing the onset of arrhythmia; applying stimulation selected from the group consisting of biphasic stimulation and conventional stimulation at a first intensity level selected from the group consisting of at the diastolic depolarization threshold, below the diastolic depolarization threshold or above the diastolic depolarization threshold; determining whether capture has occurred; increasing the stimulation intensity level by predefined increments until capture does occurs; and upon capture, continuing stimulation selected from the group consisting of biphasic stimulation and conventional stimulation at a second intensity level below the diastolic depolarization threshold. 2. A method of operating an implantable cardioverter-defibrillator (ICD), the ICD having output means for delivering electrical stimulation of a predetermined polarity, amplitude, shape and duration, the method comprising: defining a first stimulation phase with a positive polarity, a first phase amplitude, a first phase shape and a first phase duration, wherein said first phase amplitude is about 0.5 to 3.5 volts, wherein said first phase duration is about one to nine milliseconds and wherein said first stimulation phase is initiated greater than 200 milliseconds after completion of a cardiac beating cycle; defining a second phase with a negative polarity, a second phase amplitude, a second phase shape and a second phase duration, wherein said second phase amplitude is about four volts to twenty volts and wherein said second phase duration is about 0.2 to 0.9 milliseconds; and sensing the onset of arrhythmia; applying the first stimulation phase and the second stimulation phase in sequence to the cardiac tissue; determining whether capture has occurred; and increasing the stimulation intensity level by predefined increments until capture occurs. 3. A method of operating an implantable cardiac stimulator device, the stimulator device having output means for delivering electrical stimulation of a predetermined polarity, amplitude, shape and duration, the method comprising: sensing the onset of arrhythmia; applying biphasic stimulation at a first intensity level selected from the group consisting of at the diastolic depolarization threshold, below the diastolic depolarization threshold or above the diastolic depolarization threshold, wherein biphasic stimulation comprises: a first stimulation phase with a first phase polarity, a first phase amplitude, a first phase shape and a first phase duration; and a second stimulation phase with a second phase polarity, a second phase amplitude, a second phase shape and a second phase duration; wherein the first phase polarity is positive; and determining whether capture has occurred. 4. A method of operating an implantable cardiac stimulator device as in claim 3, wherein, in the event that the detecting circuitry determines that capture has not occurred, the pulse generating circuitry increases the stimulation intensity level by predefined increments until capture occurs. 5. A method of operating an implantable cardiac stimulator device as in claim 3, wherein, in the event that the detecting circuitry determines that capture has occurred, the pulse generating circuitry continues biphasic stimulation for a predetermined period of time. 6. A method of operating an implantable cardiac stimulator device as is claim 3, wherein, in the event that the detecting circuitry determines that capture has occurred, the pulse generating circuitry halts biphasic stimulation. 7. A method of operating an implantable cardiac stimulator device as in claim 3, wherein the first Abase amplitude is less than the second phase amplitude. 8. A method of operating an implantable cardiac stimulator device as in claim 3, wherein the first phase amplitude is ramped from a baseline value to a second value. 9. A method of operating an implantable cardiac stimulator device as is claim 3, wherein the first stimulation phase further comprises a series of stimulating pulses of a predetermined amplitude, polarity and duration. 10. A method of operating an implantable cardiac stimulator device as in claim 3, wherein the first phase amplitude is at a maximum subthreshold amplitude. 11. A method of operating an implantable cardiac stimulator device as in claim 3, wherein the first phase duration is at least as long as the second phase duration. 12. A method of operating an implantable cardiac stimulator device as in claim 3, wherein the first phase duration is about one to nine milliseconds. 13. A method of operating an implantable cardiac stimulator device as in claim 3, wherein the second phase duration is about 0.2 to 0.9 milliseconds. 14. A method of operating an implantable cardiac stimulator device as in claim 3, wherein the second phase amplitude is about two volts to twenty volts. 15. A method of operating an implantable cardiac stimulator device as in claim 3, wherein the second phase duration is less than 0.3 milliseconds and the second phase amplitude is greater than 20 volts. 16. A method of operating an implantable cardiac stimulator device as in claim 3, wherein the first stimulation phase is initiated greater than 200 milliseconds after completion of a cardiac beating cycle. 17. An implantable cardiac stimulator device comprising: plural electrodes (10, 12, 24); sensing circuitry connected to the plural electrodes (10, 12, 24) and adapted to sense the onset of arrhythmia; and detecting circuitry connected to the sensing circuitry (2) and adapted to detect whether capture has occurred; wherein the device is characterized by: pulse generating circuitry (2) connected to the plural electrodes (10, 12, 24) and adapted to generate, in response to the sensing circuitry, electrical pulses (102, 108, 302, 402, 408, 502, 510) of a predetermined polarity, amplitude, shape and duration to cause application of biphasic stimulation at a first intensity level selected from the group consisting of: at the diastolic depolarization threshold, below the diastolic depolarization threshold, and above the diastolic depolarization threshold; and wherein biphasic stimulation comprises: a first stimulation phase (102, 302, 402, 502) with a first phase polarity, a first phase amplitude, a first phase shape and a first phase duration; and a second stimulation phase (108, 308, 408 510) with a second phase polarity, a second phase amplitude, a second phase shape and a second phase duration; wherein the first phase (102, 302, 402, 502) polarity is positive. 18. The implantable cardiac stimulator device as in claim 17, wherein, in the event that the detecting circuitry determines that capture has not occurred, the pulse generating circuitry increases the stimulation intensity level by predefined increments until capture occurs. 19. The implantable cardiac stimulator device as in claim 17, wherein, in the event that the detecting circuitry determines that capture has occurred, the pulse generating circuitry continues biphasic stimulation far a predetermined period of time. 20. The implantable cardiac stimulator device as is claim 17, wherein, in the event that the detecting circuitry determines that capture has occurred, the pulse generating circuitry halts biphasic stimulation. 21. The implantable cardiac stimulator device as in claim 17, wherein the first Abase amplitude (302, 402, 502)is less than the second phase amplitude (308, 408, 510). 22. The implantable cardiac stimulator device as in claim 17, wherein the first phase amplitude (402) is ramped from a baseline value to a second value. 23. The implantable cardiac stimulator device as in claim 22, wherein the second value is equal to the second phase (408) amplitude. 24. The implantable cardiac stimulator device as in claim 22, wherein the second value is at a maximum subthreshold amplitude. 25. The implantable cardiac stimulator device as is claim 24, wherein the maximum subthreshold amplitude is about 0.5 to 3.5 volts. 26. The implantable cardiac stimulator device as in claim 22, wherein the first phase (102, 202, 302, 402) duration is at least as long as the second phase (108, 208, 308, 408) duration. 27. The implantable cardiac stimulator device as in claim 22, wherein the first phase (102, 202, 302, 402) duration is about one to nine milliseconds. 28. The implantable cardiac stimulator device as in claim 22, wherein the second phase (108, 208, 308, 408, 510) duration is about 0.2 to 0.9 milliseconds. 29. The implantable cardiac stimulator device as in claim 22, wherein the second phase amplitude phase (108, 208, 308, 408, 510) is about two volts to twenty volts. 30. The implantable cardiac stimulator device as in claim 22, wherein the second phase duration phase (108, 208, 308, 408, 510) is less than 0.3 milliseconds and the second phase amplitude is greater than 20 volts. 31. The implantable cardiac stimulator device as is claim 17, wherein the first stimulation phase (502) further comprises a series of stimulating pulses of a predetermined amplitude, polarity and duration. 32. The implantable cardiac stimulator device as in claim 31, wherein the first stimulation phase (502) further comprises a series of rest periods. 33. The implantable cardiac stimulator device as in claim 32, wherein applying the first stimulation phase (502) further comprises applying a rest period of a baseline amplitude after at least one stimulating pulse. 34. The implantable cardiac stimulator device as in claim 33, wherein the rest period is of equal duration to the duration of the stimulating pulse. 35. The implantable cardiac stimulator device as in claim 17, wherein the first phase amplitude (102, 202, 302, 402, 502 is at a maximum subthreshold amplitude. 36. The implantable cardiac stimulator dev