THE MICROVASCULAR DISTRIBUTION OF CARDIOPLEGIC SOLUTION IN THE PIGLETHEART - RETROGRADE VERSUS ANTEGRADE DELIVERY

The uniform distribution of cardioplegic solution to all areas of the microvasculature is considered critical for myocardial protection. Des pite this, little information exists regarding the ability of retrogra dely infused cardioplegic solution to perfuse the microvasculature of the heart. In this report, the microvascular distribution of retrograd ely delivered cardioplegic solution was studied by means of a techniqu e to quantitatively demonstrate capillary perfusion. Duroc piglet hear ts were subjected to either antegrade (n = 4) or retrograde (n = 8) pe rfusion fixation with 2.5% glutaraldehyde and subsequently perfused wi th NTB-2 (an intracapillary marker). The results indicate that retrogr adely delivered NTB-2 consistently perfused the anterior half of the i ntraventricular septum and the anterior and lateral free walls of the left ventricle but inconsistently perfused the posterior half of the i ntraventricular septum, the posterior wall of the left ventricle, and a small paraseptal region of the right ventricle. The remainder of the right ventricle was not perfused. In contradistinction, all regions o f the heart were consistently perfused by the antegrade technique. In regions of the heart in which retrograde microvascular perfusion occur red, no statistical difference was found in the quantitative degree of capillary perfusion achieved by either the antegrade or retrograde te chnique. These results have important implications for planning strate gies of myocardial protection and suggest that further investigation c oncerning the microvascular distribution of retrogradely delivered car dioplegic solution in human beings is merited.