The mechanical atrioventricular time of isolated hearts as a correlate of the atrioventricular conduction time.

The time difference between onset of contraction in right atrium and left ventricle of isolated guinea pig hearts (mechanical AV time) was measured continuously by an impulse-triggered interval counter and taken as an equivalent of the electrophysiological AV conduction time derived from the epicardial ECG. Excellent correlation between these two parameters was established over a broad range of experimentally modified conduction times. The method was used to analyze the influence of electrical pacing, epinephrine, Ca2+ ions, and adenosine both on the AV conduction and on functional parameters of the hearts and revealed advantages in comparison to separate tests of single parameters in different experimental arrangements.