Cardiac pacemaker with hysteresis behavior
First Claim
1. In a pacemaker having a programmable lower rate and upper rate, a programmable lower rate hysteresis (LRH) corresponding to a lower rate hysteresis interval (LRHI), and a programmable intermediate pacing rate (IR) the improvement comprising:
- A. means for measuring rate of change MAVG of successive cardiac intrinsic escape intervals;
B. means for comparing MAVG to a first predefined limit SL1 ;
C. means for comparing the last intrinsic escape interval to the lower rate hysteresis interval (LRHI); and
D. means for stimulating a heart at the lower rate hysteresis (LRH) and for gradually incrementing a pacing rate until the pacing ratio reaches the intermediate pacing rate (IR) if the last intrinsic escape interval is longer than the lower rate hysteresis interval (LRHI) and if said MAVG is greater than SL1.
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Accused Products
Abstract
A pacemaker having a hysteresis feature which permits intrinsic heart activity, controlled by the sinus node to resume optimally after pacing. The pacemaker has a programmable lower rate and upper rate, a programmable lower hysteresis rate (LRH) corresponding to a lower rate hysteresis interval (LRHI), and a programmable rate (IR) intermediate an upper pacing rate (UR) and a lower pacing rate (LR). A microprocessor measures the average rate of change MAVG in the intervals between consecutive ventricular depolarizations, and compares the last intrinsic escape interval RRN to the lower rate hysteresis interval (LRHI).
If the last intrinsic escape interval RRN is longer than the lower rate hysteresis interval (LRHI), and if the value of MAVG is greater than a first preselected value SL1 but less than a second preselected value SL2, the pacemaker stimulates at the lower rate hysteresis (LRH) and thereafter gradually increases the pacing rate up to the intermediate rate (IR). A time counter maintains a continuous pacing at the intermediate rate (IR) for a predefined period of time, and the pacing rate is gradually decreased toward the lower pacing rate (LR).
247 Citations
22 Claims
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1. In a pacemaker having a programmable lower rate and upper rate, a programmable lower rate hysteresis (LRH) corresponding to a lower rate hysteresis interval (LRHI), and a programmable intermediate pacing rate (IR) the improvement comprising:
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A. means for measuring rate of change MAVG of successive cardiac intrinsic escape intervals; B. means for comparing MAVG to a first predefined limit SL1 ; C. means for comparing the last intrinsic escape interval to the lower rate hysteresis interval (LRHI); and D. means for stimulating a heart at the lower rate hysteresis (LRH) and for gradually incrementing a pacing rate until the pacing ratio reaches the intermediate pacing rate (IR) if the last intrinsic escape interval is longer than the lower rate hysteresis interval (LRHI) and if said MAVG is greater than SL1. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A method for pacing with a pacemaker having a programmable lower rate and upper rate, a programmable lower hysteresis rate (LRH) corresponding to a lower rate hysteresis interval (LRHI), and a programmable intermediate pacing rate (IR), the pacing method comprising the steps of:
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A. measuring a rate of change of MAVG of successive intrinsic escape intervals; B. comparing MAVG to a first predetermined limit SL1 ; C. comparing a last intrinsic escape interval RRN to the lower rate hysteresis interval (LRHI); and D. stimulating at the lower rate hysteresis (LRH) and gradually incrementing a pacing rate until it reaches the intermediate pacing rate (IR) if the RRN interval will be longer than the lower rate hysteresis interval (LRHI) and if said MAVG is greater than SL1. - View Dependent Claims (17, 18, 19, 20, 21, 22)
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Specification