54 results about "Av interval" patented technology

Rate responsive pacing is limited in an atrial based pacing mode by the AV interval in order to avoid or minimize ventricular encroachment of atrial pacing. The AV or VA interval is used to permit rate responsiveness; modulate rate responsiveness or to determine a dynamic upper sensor rate.

This document provides a simple and automatic method for determining an optimal AV interval and / or range of AV intervals for, in an exemplary embodiment, LV-only pacing. Such a method provides significant advantages for patients while reducing burdens related to post-implant follow-up by clinicians in that it greatly reduces the need for doing echocardiographic-based AV interval optimization procedures as well as providing a way to dynamically optimize AV intervals as the patient moves about their activities of daily living (ADL).

An implantable medical device operates to promote intrinsic ventricular depolarization according to a pacing protocol. The medical device monitors the AV interval and adjusts the Ventricular Pacing Protocol if the AV interval exceeds a threshold when the cardiac rate is elevated.

Methods and apparatus of left ventricular pacing including automated adjustment of a atrio-ventricular (AV) pacing delay interval and intrinsic AV nodal conduction testing. Thus, in the event that the AV conduction test reveals a physiologically acceptable intrinsic PR interval then storing the physiologically acceptable PR interval in a memory structure (e.g., a median P-R from one or more cardiac cycles) and delivering fusion pacing using a decremented value of the intrinsic PR interval.

The present invention provides a technique for verifying pacing capture of a ventricular chamber, particularly to ensure desired delivery of a ventricular pacing regime (e.g., “CRT”). The invention also provides ventricular capture management by delivering a single ventricular pacing stimulus and checking inter-ventricular conduction during a temporal window to determine if the stimulus captured. If a loss-of-capture LOC) signal results from the capture management testing, then the applied pacing pulses are modified and the conduction test repeated. If LOC, an alert message can issue. Other aspects include: use of a trend of A-RV / LV and LV-RV timing intervals to monitor changes in the patient's heart conduction properties; bi-ventricular verification test and search—while still pacing BiV by detecting latent sense; single-V pacing threshold search, use of timing of sense in other V chamber to establish capture and LOC windows; (iv) use of a premature V pace rather than short AV interval if VV cannot be discriminated from AV; (v) option to run a threshold search only if the Bi-ventricular verification test fails.

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.

Impedance, e.g. 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. Other methods vary the AA interval to maximize impedance change over the entire cardiac cycle or during the atrial cycle.

A cardiac rhythm management system includes techniques for computing an indicated pacing interval, AV delay, or other timing interval. In one embodiment, a variable indicated pacing interval is computed based at least in part on an underlying intrinsic heart rate. The indicated pacing interval is used to time the delivery of biventricular coordination therapy even when ventricular heart rates are irregular, such as in the presence of atrial fibrillation. In another embodiment, a variable filter indicated AV interval is computed based at least in part on an underlying intrinsic AV interval. The indicated AV interval is used to time the delivery of atrial tracking biventricular coordination therapy when atrial heart rhythms are not arrhythmic. Other indicated timing intervals may be similarly determined. The indicated pacing interval, AV delay, or other timing interval can also be used in combination with a sensor indicated rate indicator.