Electrophysiologic evaluation of cardiovascular agents in the isolated intact rabbit heart

A modification of the Langendorff perfused rabbit heart is described. This model can be used to perform electrophysiologic studies in the isolated heart and is ideally suited for acute pharmacologic evaluation. His bundle electrograms were measured with a plunge electrode and allowed atrioventricular (AV) nodal physiology to be directly and precisely evaluated. Atrial conduction and refractoriness, atrioventricular node conduction and refractoriness, His-Purkinje conduction, and ventricular conduction and refractoriness could be accurately measured. Verapamil had a depressant effect on AV nodal conduction and refractoriness without affecting His--Purkinje conduction or myocardial refractoriness. Flecainide prolonged atrial conduction and His-Purkinje conduction with less effect on AV nodal physiology. The use of this isolated perfused rabbit heart model is an inexpensive and reliable technique for the evaluation of the electrophysiologic effects of pharmacologic agents on the conduction system of the heart. A major advantage of the isolated heart model is the absence of autonomic reflexes, which can confound studies performed in intact animals.