Ultrastructural and electrophysiologic changes of experimental acute cardiac lymphostasis.

Experimental impairment of cardia lymph flow in dogs produced histologic and electrophysiologic changes in the heart. Interstitial edema, lipid swelling of myofibrils, dilatation of lymph vessels, and fibrinoid degeneration of small coronary arteries occurred in and near the sinus node and the atrioventricular conduction system. On electrical stimulation of the heart, significant shortening of the atrial and ventricular effective refractory periods, increases in the sinus node recovery time and in the atrioventricular conduction time, and ventricular extrasystoles and ventricular fibrillation were observed. Many of these EKG changes are similar to those observed in sick sinus syndrome in man. An attempt was made to create dynamic lymphatic insufficiency by rapid electrical stimulation of the heart. EKG abnormalities observed in these cases could be prevented by intravenous injection of calcium dobesilate.