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An improved pacing system and related method for use in an implantable pacemaker or defibrillator are disclosed which operate using a predetermined subset of combinations of possible combinations for pacing stimulus pulse amplitude and pulse width, which subset of combinations are the most energy-ef

An improved pacing system and related method for use in an implantable pacemaker or defibrillator are disclosed which operate using a predetermined subset of combinations of possible combinations for pacing stimulus pulse amplitude and pulse width, which subset of combinations are the most energy-efficient pairs, thereby ensuring reduced battery current drain. This is accomplished by ensuring that each combination has the lowest battery charge drain of any combination having at least the rheobase value of that particular combination as a function of cardiac chronaxie. The preferred embodiment of the pacing system of the present invention includes capture verification to enable a substantially reduced safety margin to further minimize the level of battery charge drain. The preferred embodiment of the pacing system of the present invention also includes the capability to produce a safety backup pulse, to ensure that the pacing system never misses a beat. The preferred embodiment of the pacing system of the present invention further includes the capability to initially and periodically determine the stimulation threshold and cardiac chronaxie.

대표청구항 ▼

An improved pacing system and related method for use in an implantable pacemaker or defibrillator are disclosed which operate using a predetermined subset of combinations of possible combinations for pacing stimulus pulse amplitude and pulse width, which subset of combinations are the most energy-ef

An improved pacing system and related method for use in an implantable pacemaker or defibrillator are disclosed which operate using a predetermined subset of combinations of possible combinations for pacing stimulus pulse amplitude and pulse width, which subset of combinations are the most energy-efficient pairs, thereby ensuring reduced battery current drain. This is accomplished by ensuring that each combination has the lowest battery charge drain of any combination having at least the rheobase value of that particular combination as a function of cardiac chronaxie. The preferred embodiment of the pacing system of the present invention includes capture verification to enable a substantially reduced safety margin to further minimize the level of battery charge drain. The preferred embodiment of the pacing system of the present invention also includes the capability to produce a safety backup pulse, to ensure that the pacing system never misses a beat. The preferred embodiment of the pacing system of the present invention further includes the capability to initially and periodically determine the stimulation threshold and cardiac chronaxie. lly removing the pacing therapy after a predetermined amount of time.11. The method of claim 1, wherein the cross-check parameter comprises a first cross-check parameter and further comprising: determining a second cross-check parameter affected at least in part by the change in the patient's position; and selectively administering pacing therapy to the patient based on the position parameter, the first cross-check parameter, and a second cross-check parameter. 12. One or more computer-readable media having computer-readable instructions thereon which, when executed by a programmable stimulation device, cause the stimulation device to execute the method of claim 1.13. A method of administering pacing therapy for orthostatic hypotension, comprising: detecting a postural change in a patient from a horizontal position to an upright position; confirming the postural change using a cross-check parameter; and adjusting a cardiac pacing rate from a first pacing rate to a second pacing rate effective to counteract effects of orthostatic hypotension in response to detection of the postural change in the patient's position and confirmation of the postural change via the cross-check parameter. 14. The method of claim 13, wherein the detecting comprises: monitoring positional data generated by a 3D accelerometer; and detecting, from the positional data, the change from the horizontal position to the upright position. 15. The method of claim 13, wherein the detecting comprises detecting the change for a specified period of time.16. The method of claim 13, wherein the confirming comprises detecting changes in an evoked response amplitude.17. The method of claim 13, wherein the determining a cross-check parameter is selected from a group of parameters comprising stroke volume, a cardiac impedance parameter, evoked response integral, ventricular wall thickness, ventricular pressure, atrial evoked response amplitude, and atrial evoked response integral.18. The method of claim 13, wherein the confirming comprises: monitoring an evoked response parameter (ERP) functionally related to an evoked response amplitude (ERA); computing a delta ERP (&Dgr;ERP) as a function of the ERP and a moving average of the ERP; and evaluating the &Dgr;ERP computed at approximately a time when the position parameter indicates the change in the patient's position. 19. The method of claim 13, further comprising adjusting the cardiac pacing rate back toward the first pacing rate.20. The method of claim 13, further comprising adjusting the cardiac pacing rate back toward the first pacing rate after a predetermined amount of time.21. One or more computer-readable media having computer-readable instructions thereon which, when executed by a programmable stimulation device, cause the stimulation device to execute the method of claim 13.22. A method comprising: detecting a postural change in a patient; evaluating an evoked response parameter functionally related to an evoked response amplitude for an indication of the postural change; and applying cardiac pacing therapy in response to detection of the postural change that is additionally confirmed by the evoked response parameter. 23. The method of claim 22, wherein the evaluating comprises: monitoring the evoked response parameter (ERP); computing a delta ERP (&Dgr;ERP) as a function of the ERP and a moving average of the ERP; examining the &Dgr;ERP computed at approximately at time when the postural change is detected; and in an event that the &Dgr;ERP changes by a predetermined amount, confirming that the postural change did occur. 24. One or more computer-readable media having computer-readable instructions thereon which, when executed by a programmable stimulation device, cause the stimulation device to execute the method of claim 22.25. A method comprising: increasing a pacing rate in a cardiac stimulation device from a first rate to a higher second rate upon (1) detect ion of a change in patient's position and (2) confirmation of the change using a non-position parameter; and subsequently decreasing the pacing rate back toward the first rate. 26. The method of claim 25, wherein the non-position parameter is selected from a group of parameters comprising stroke volume, a cardiac impedance parameter, evoked response integral, ventricular wall thickness, ventricular pressure, atrial evoked response amplitude, and atrial evoked response integral.27. The method of claim 25, further comprising decreasing the pacing rate after a predetermined period of time.28. One or more computer-readable media having computer-readable instructions thereon which, when executed by a programmable stimulation device, cause the stimulation device to execute the method of claim 25.29. A cardiac stimulation device comprising: a position sensor to sense a position parameter indicative of changes in a patient's position; a processor operably coupled to the position sensor, the processor being configured to determine when to administer cardiac pacing therapy to the patient based on the position parameter and a second cross-check parameter that is affected by the change in the patient's position and is used to confirm a position change sensed by the position sensor; and a pacing generator configured to administer the cardiac pacing therapy as directed by the processor. 30. The cardiac stimulation device of claim 29, wherein the position sensor comprises a 3D accelerometer.31. The cardiac stimulation device of claim 29, wherein the position sensor is configured to sense a change from a horizontal position to an upright position.32. The cardiac stimulation device of claim 29, wherein the cross-check parameter comprises a ventricular evoked response amplitude.33. The cardiac stimulation device of claim 29, wherein the cross-check parameter comprises a cross-check parameter is selected from a group of parameters comprising stroke volume, a cardiac impedance parameter, evoked response integral, ventricular wall thickness, ventricular pressure, atrial evoked response amplitude, and atrial evoked response integral.34. The cardiac stimulation device of claim 29, wherein the processor determines to administer cardiac pacing therapy when the position sensor detects a postural change from a horizontal position to an upright position and the cross-check parameter confirms the postural change.35. The cardiac stimulation device of claim 34, wherein the pacing generator increases a pacing rate from a first rate to a higher second rate.36. The cardiac stimulation device of claim 34, wherein the pacing generator generates a pacing rate effective to counteract effects of orthostatic hypotension.37. The cardiac stimulation device of claim 34, wherein the pacing generator administers the cardiac pacing therapy for a predetermined period of time.38. An implantable cardiac rhythm management device, comprising: position sensing means for sensing a change in a patient's position from a horizontal position to an upright position; evaluation means for evaluating a cross-check parameter affected by the change in the patient's position; and therapy delivery means, responsive to the position sensing means and the evaluation means, for generating cardiac stimulating pulses at an increased rate effective to treat orthostatic hypotension when the position sensing means senses a postural change from a horizontal position to an upright position and the evaluation means confirms the postural change. 39. The implantable cardiac rhythm management device of claim 38, wherein the evaluation means comprises detecting means for detecting changes in an evoked response amplitude.40. The implantable cardiac rhythm management device of claim 38, wherein the therapy delivery means systematically reduces the pulse rate following treatment of the orthostatic hypotension.41. A programmable cardiac stimulation device having a memory and a processor, the cardiac stimulation device being programmed to perform tasks comprising: administering pacing therapy to a patient when the device (1) detects a postural change from a horizontal position to an upright position and (2) confirms the postural change using a cross-check parameter; and subsequently removing the pacing therapy in a systematic manner. 42. The programmable cardiac stimulation device of claim 41, wherein the cross-check parameter comprises an evoked response amplitude.43. The programmable cardiac stimulation device of claim 41, wherein the cross-check parameter comprises a cross-check parameter is selected from a group of parameters comprising stroke volume, a cardiac impedance parameter, evoked response integral, ventricular wall thickness, ventricular pressure, atrial evoked response amplitude, and atrial evoked response integral.44. The programmable cardiac stimulation device of claim 41, wherein the cardiac stimulation device is programmed to perform additional tasks comprising: monitoring an evoked response parameter (ERP) functionally related to an evoked response amplitude (ERA); computing a delta ERP (&Dgr;ERP) as a function of the ERP and a moving average of the ERP; examining the &Dgr;ERP computed at approximately at time when the postural change is detected; and in an event that the &Dgr;ERP changes by a predetermined amount, confirming that the postural change did occur.