Algorithm for the automatic determination of optimal AV and VV intervals

A method for setting an optimal atrial to ventricular (AV) interval in a pacing device, the method comprising:

• 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 and wherein the measuring impedance includes measuring the impedance near the V-pace and at a plurality of time points after the V-pace and to find a cardiac cycle impedance maximum, and the calculating includes taking the difference of the largest measured impedance and the impedance measured near the V-pace.

A method for setting an optimal atrial to ventricular (AV) interval in a pacing device, the method comprising:

• 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 and wherein the measuring impedance includes measuring the impedance near an A-event and near a V-pace, and the calculating includes taking the difference of the A-event and V-pace measured impedances.

A method for setting an optimal atrial to ventricular (AV) interval in a pacing device, the method comprising:

• 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 in the largest impedance change;
• and
• setting the AV interval in the pacing device to the AV interval causing the largest impedance change and wherein the pacing device is implanted in a patient and the patient has a breathing cycle including an inhaled maximum impedance time region and an exhaled minimum impedance time region, the method further comprising tracking the breathing cycle of the patient to produce breathing cycle data indicating a position within the breathing cycle, wherein at least part of the measuring impedance occurs during the exhaled minimum impedance time region to produce the measured impedance data.

A method for setting an optimal atrial to ventricular (AV) interval in a pacing device, the method comprising:

• 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 and wherein the pacing device is implanted in a patient and the patient has a breathing cycle including an inhaled maximum impedance time region and an exhaled minimum impedance time region, further comprising tracking the breathing cycle of the patient to produce breathing cycle positional data indicating the position within the breathing cycle, wherein at least part of the measuring cardiac impedance occurs during period of substantially unchanging breathing impedance contribution to produce an impedance measurement data set less affected by breathing.