Algorithm for the automatic determination of optimal AV and VV intervals
First Claim
1. A method for finding the minimum impedance time point within an AV interval in a heart, the method comprising:
- setting the AV interval to a substantially longer time period than physiologically optimal;
measuring the impedance at a plurality of time points over the AV interval to find a time of minimal impedance; and
setting AV interval as a function of the time of minimal impedance.
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Accused Products
Abstract
Methods and devices for determining optimal Atrial to Ventricular (AV) pacing intervals and Ventricular to Ventricular (VV) delay intervals in order to optimize cardiac output. Impedance, preferably sub-threshold impedance, is measured across the heart at selected cardiac cycle times as a measure of chamber expansion or contraction. One embodiment measures impedance over a long AV interval to obtain the minimum impedance, indicative of maximum ventricular expansion, in order to set the AV interval. Another embodiment measures impedance change over a cycle and varies the AV pace interval in a binary search to converge on the AV interval causing maximum impedance change indicative of maximum ventricular output. Another method varies the right ventricle to left ventricle (VV) interval to converge on an impedance maximum indicative of minimum cardiac volume at end systole. Another embodiment varies the VV interval to maximize impedance change.
120 Citations
56 Claims
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1. A method for finding the minimum impedance time point within an AV interval in a heart, the method comprising:
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setting the AV interval to a substantially longer time period than physiologically optimal;
measuring the impedance at a plurality of time points over the AV interval to find a time of minimal impedance; and
setting AV interval as a function of the time of minimal impedance. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for setting an optimal atrial to ventricular (AV) interval in a pacing device, the method comprising:
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measuring the impedance for at least two points in a cardiac cycle to produce measured impedance data;
calculating an impedance change using the measured impedance data;
searching for an AV interval causing the largest impedance change, wherein the AV interval searching includes varying the AV interval responsive to the measured impedance change to converge on the largest impedance change; and
setting the AV interval in the pacing device to the AV interval causing the largest impedance change. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32)
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33. A method for setting an optimal right ventricle to left ventricle (VV) pacing interval for use in a pacing device, the method comprising:
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searching for a VV interval causing the largest cardiac cycle maximum impedance, wherein the VV interval searching includes measuring the impedance in the cardiac cycle, determining the cardiac cycle maximum impedance, and varying the paced VV interval responsive to the cardiac cycle maximum impedance to converge on the largest cardiac cycle maximum impedance; and
setting the VV interval pacing interval in the pacing device to the VV interval causing the largest cardiac cycle maximum impedance. - View Dependent Claims (34, 35, 36, 37, 38, 39, 40)
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41. A method for setting an optimal right ventricle to left ventricle (VV) pacing interval for use in a pacing device, the method comprising:
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searching for a VV interval causing the largest cardiac cycle impedance change, wherein the VV interval searching includes measuring impedance in the cardiac cycle, calculating a cardiac cycle impedance change, and varying the paced VV interval responsive to the cardiac cycle impedance change to converge on the largest cardiac cycle impedance change; and
setting the VV interval pacing interval in the pacing device to about the VV interval causing the largest cardiac cycle impedance change. - View Dependent Claims (42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55)
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56. A processor readable medium containing instructions to cause the processor to utilize an implantable medical device (IMD for cardiac output optimization, the combination comprising:
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means for setting an AV interval to a substantially longer time than physiologically optimal;
means for pacing and sensing at least one atrial chamber of a heart;
means for measuring impedance at multiple times over said AV interval for a plurality of cardiac cycles;
means for setting an AV optimal contraction time equal to a time when said impedance is at a minimum; and
means for setting said AV interval equal to said AV optimal contraction time adjusted by a constant.
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Specification