Dual chamber pacing with interchamber delay

Claim 3

The method of claim 1 further comprising the steps of: positioning said second electrode to sense a signal from a left atrium of said heart; providing said third electrode as a ground electrode; sensing for said cardiac signal in said unipolar configuration between said second electrode and said third electrode.

Claim 4

The method of claim 1 further comprising the step of pacing said first chamber if said cardiac signal originates in said second chamber.

Claim 5

The method of claim 1 further comprising the steps of: providing said first electrode for one of sensing and pacing a first chamber of said heart; providing said second electrode for one of sensing and pacing a second chamber of said heart; commencing a conduction time interval if said cardiac signal originates in said first chamber; sensing for said cardiac signal in said second chamber between said second electrode and said third electrode while in said unipolar configuration; and pacing said second chamber if after said conduction time interval elapses said cardiac signal is not sensed in said second chamber.

Claim 6

The method of claim 4 in which: said first chamber is a right atrium of said heart; said second chamber is a left atrium of said heart; and said conduction time interval is equal to an intra-atrial conduction time.

Claim 7

The method of claim 4 in which: said first chamber is a right ventricle of said heart; said second chamber is a left ventricle of said heart; and said conduction time interval is equal to an intra-ventricular conduction time.

Claim 10

The method of claim 7 further comprising the step of pacing said second chamber if after said conduction time interval elapses said cardiac signal is not sensed in said second chamber.

Claim 11

The method of claim 7 further comprising the step of switching said first and second electrodes back to said bipolar configuration after sensing for said cardiac signal in said unipolar configuration.

Claim 12

The method of claim 9 in which: said conduction time interval is about equal to a time required for said cardiac signal to propagate from said first chamber to said second chamber; and said switching occurs after said conduction time interval elapses.

Claim 13

An implantable medical device for determining the origin of a cardiac signal in a heart, comprising: a conductive housing; control circuitry enclosed within said housing; a first electrode electrically connected to said control circuitry, and electrically connectable with a first chamber of said heart; a second electrode electrically connected to said control circuitry, and electrically connectable with a second chamber of said heart; an indifferent electrode electrically connected to said housing; means for connecting said first and second electrodes in a bipolar configuration, wherein sensing for said cardiac signal occurs between said first and second electrodes; means for switching said first and second electrodes to a unipolar configuration after said cardiac signal is sensed in said bipolar configuration, wherein sensing for said cardiac signal occurs between said indifferent and second electrodes: and means responsive to a detected signal at one said first or second electrodes in unipolar configuration for determining the origin of said signal in said first or second chamber of said heart.

Claim 14

An implantable medical device for determining the origin of a cardiac signal in a heart, comprising: a conductive housing; control circuitry enclosed within said housing; a first electrode electrically connected to said control circuitry, and electrically connectable with a first chamber of said heart; a second electrode electrically connected to said control circuitry, and electrically connectable with a second chamber of said heart; an indifferent electrode electrically connected to said housing; means for connecting said first and second electrodes in a bipolar configuration, wherein sensing for said cardiac signal occurs between said first and second electrodes; means for switching said first and second electrodes to a unipolar configuration after said cardiac signal is sensed in said bipolar configuration, wherein sensing for said cardiac signal occurs between said indifferent and second electrodes: and means responsive to a detected signal at one said first or second electrodes in unipolar configuration for determining the origin of said signal in said first or second chamber of said heart.

Claim 15

The implantable medical device of claim 11 further comprising means for paging said first chamber if said cardiac signal originates in said second chamber.

Claim 16

The implantable medical device of claim 11 in which: said first chamber is the right atrium of said heart; and said second chamber is the left atrium of said heart.

Claim 17

The implantable medical device of claim 13 further comprising means for stimulating said left atrium after an intra-atrial conduction time so said left atrium contracts before the left ventricle of said heart.

Claim 18

The implantable medical device of claim 13 further comprising means for stimulating said right atrium, means for stimulating said left atrium; and means for controlling said stimulating means to stimulate said left atrium before said right atrium in order to reduce occurrence of an atrial arrhythmia in said left and right atria.

Claim 19

The implantable medical device of claim 11 in which: said first chamber is a right ventricle of said heart; and said second chamber is a left ventricle of said heart.