Dual chamber pacemaker with automatically optimized AV delay

A method of dual chamber operation by a pacing system implanted in a patient, said pacing system having atrial sense means for sensing natural atrial events (AS) and atrial pace means for delivering atrial pace pulses (AP), ventricular pace means for delivering ventricular pace pulses (VP), synchronizing means for controlling delivery of a said VP at an AV interval following either an AS or AP according to a function AV=f(rate), said method of operation further comprising determining an optimum AV interval at at least one rate, and adjusting said function in accordance with said optimum AV interval, said determining step comprising:

• switching said implanted pacing system into a mode wherein AP and VP pulses are delivered to the patient at a predetermined rate, each VP following a prior AP by an AV interval,
• testing the AV interval by adjusting the AV interval to a plurality of adjusted intervals, and determining a measure of the patient QT interval corresponding to each respective adjusted AV interval, and
• determining from said measures of QT intervals whether the AV interval at said predetermined rate should be changed, and changing the value of the AV interval corresponding to said predetermined rate in accordance with said testing.

A dual chamber pacemaker having means for sensing atrial heartbeats (AS) and for generating ventricular pace pulses (VP) each synchronized to a preceding AS, comprising means for determining the QT intervals following a series of delivered VPs, means for analyzing said QT intervals, and AV means for setting the AV interval between an AS and a following VP, said AV means having adjusting means for adjusting said AV interval as a function of said analyzed QT intervals.

A rate responsive dual chamber pacemaker having means for sensing atrial heartbeats (AS), means for generating atrial pace pulses (AP) at a rate variable through a rate range, means for generating ventricular pace pulses (VP) at a rate variable through said rate range, means for synchronizing a VP to a preceding AS, AV means for setting the AV interval between an AS or AP and a following VP, and variable means for sensing the value of a predetermined variable representative of patient cardiac hemodynamics, characterized by

• determining means for determining the variation of said predetermined variable with variation of AV interval, and
• said AV means having adjusting means for adjusting said AV interval in accordance with said determined variation.

A dual chamber pacemaker having means for sensing atrial heartbeats (AS), means for generating atrial pace pulses (AP), means for generating ventricular pace pulses (VP), lead means for delivering said pace pulses and sensing ventricular heartbeats (VS), means for synchronizing a VP to a preceding AS, AV means for setting the AV interval between an AS or AP and a following VP, variable means for sensing the value of a predetermined variable representative of patient cardiac hemodynamics, rate control means for controlling the rate of said ventricular pace pulses as a function of said variable, and characterized by

• change means for changing said AV interval in a predetermined manner,
• determining means for determining the change in said variable attributable to said AV interval change, and said AV means having adjust means for adjusting the AV interval in accordance with said attributable variable change.