VENTRICULAR EFFLUENT OF RETROGRADE CARDIOPLEGIA IN HUMAN HEARTS HAS TRAVERSED CAPILLARY BEDS

Background. In human hearts, as much as two thirds of retrograde cardi oplegia is shunted through thebesian and arteriosinusoidal channels in to the ventricular cavities. This ventricular effluent is believed to have bypassed the myocardial capillary beds and is therefore considere d nonnutritive. Methods. To test this hypothesis, we studied the expla nted hearts from 9 cardiac transplant recipients with the diagnosis of idiopathic cardiomyopathy. These hearts were arrested in situ with co ld blood cardioplegia and excised with the coronary sinus intact. The left and right coronary ostia and the coronary sinus then were cannula ted. Colored microspheres (15 +/- 5 mu m) mixed in 37 degrees C blood cardioplegia were administered through the coronary sinus at a pressur e of 30 to 40 mm Hg. Effluents from the coronary arteries and ventricu lar chambers were collected and analyzed for microsphere concentration . Results. Approximately 80% of retrograde cardioplegia solution was r ecovered in the ventricular chambers. Nearly 40% of this ventricular c hambers effluent had traversed capillary beds and, thus, we believe ha s nutritive properties. Almost all of the coronary artery effluent of retrograde cardioplegia solution had traversed capillary beds. The tot al nutritive fraction of retrograde warm blood cardioplegia in this ex planted human heart model was approximately 55%. Conclusions. These fi ndings suggest that the ventricular chamber effluent of retrograde blo od cardioplegia contributes to the metabolic homeostasis of the arrest ed human heart.