A method for simultaneous epicardial monophasic action potential recordings from the dog heart in situ.

In order to record epicardial monophasic action potentials (MAP) simultaneously from different regions of intact beating hearts, we developed a tripodal suction electrode device (total weight 1.5 g, distance between the flexible silicone legs 25 mm) which we tested in pentobarbital anaesthetized open chest dogs. The device was easy to apply and gave stable and reproducible recordings. Repolarization times for epicardial left ventricular and endocardial right ventricular MAPs correlated well (r = 0.97, P less than 0.001). There was no correlation between MAP amplitude and repolarization times. The beta 1-adrenergic agonist prenalterol decreased MAP duration, while the new class III antiarrhythmic drug melperone increased MAP duration. Mild ischaemia effected MAP prolongation and severe ischaemia MAP shortening, compared to simultaneous recordings from non-ischaemic ventricular regions. We conclude that the new tripodal suction electrode is a simple device for simultaneous recording of multiple MAPs. The method should be suitable for studies of electrophysiological effects of drugs and other interventions in intact beating hearts.