The influence of non-coronary collateral blood supply on the electively arrested heart during ischemia and reperfusion

Abstract

To study the influence of non-coronary collateral blood circulation (NCCBC) on the integrity of the ischemic myocardium a right-sided thoracotomy was performed on 15 anesthetized dogs. Following a total cardiopulmonary bypass (CPB), ventricular fibrillation was induced, during which 2,000 ml calcium-free cardioplegic solution LK 352 was given at the aortic root over an 8-10 min period. Precautions were taken to prevent retrograde blood flow into the coronary system via the coronary sinus. After 90 min of ischemia, ten of the dog hearts were reperfused with systemic blood for the next 30 min. Transmural biopsies were taken from the apex of the left ventricle at the following intervals: (1) before CPB, (2) immediately after the infusion of LK 352, (3) following 90 min of ischemia, (4) after 5 min, (5) after 15 min, and finally (6) after 30 min of reperfusion and were then studied ultrastructurally. The presence of NCCBC was documented by the observation of erythrocyte-filled blood vessels in the biopsies corresponding to nos. 2 and 3 of the above. To assess the degree of ischemic injury and the extent of myocardial recovery during reperfusion, a scoring system based on a semiquantitative assessment of the characteristic morphological changes was used. The average result of the separately assessed subendo- and subepicardial layers represented the score, which was plotted on the ischemic injury and the recovery scale, thus making a direct comparison of the hearts possible. All the hearts generously supplied with blood via extracoronary routes during ischemia showed minimal and reversible ischemic injuries. They recovered more quickly and more completely following reperfusion than those hearts without NCCBC. From these results we conclude that despite its warming-up effect on the myocardium and its tendency to wash out the cardioplegic solution, the NCCBC generally protects the myocardium from serious ischemic injuries and shortens the period of recuperation during the reperfusion.

Blood Cardioplegia Serves as a Bicarbonate Donor to the Myocardium during Ischemia: Effects of Anoxia and Hypercapnia on Acid-Base Characteristics of Blood Cardioplegic Solution

“…The influence of noncoronary collateral flow [20,21] during cardioplegic arrest on the [Cl – ] and [K + ] decrease of the coronary sinus effluent cannot be ignored because the [Cl – ] and [K + ] of circuit blood were lower than those of the BCP solution. Although noncoronary collateral flow obviously affected our results, the relative contribution of the noncoronary collateral flow to the results of the present study could not be determined because the exact volume of noncoronary collateral flow circulating in the myocardium during cardioplegic arrest during aortic cross-clamping is unknown.…”

Noncoronary Collateral Myocardial Blood Flow: The Human Heart’s Forgotten Blood Supply

“…This suggests that the increase in NCCMBF provided an alternative blood supply during myocardial ischemia. In myocardial biopsies from dogs subjected to cardiopulmonary bypass and cardioplegic arrest, the presence of erythrocyte-filled blood vessels pointed to the possibility of direct access of NCCMBF to the heart, despite correct aortic cross-clamping [ 55 ]. Notwithstanding the compensatory effect of NCCMBF in ischemic heart disease, its role in cardiac surgery may be detrimental.…”

“…Notwithstanding the compensatory effect of NCCMBF in ischemic heart disease, its role in cardiac surgery may be detrimental. Very few authors suggested that NCCMBF could reduce ischemic injury [ 55 ]. The majority believed NCCMBF could be detrimental because it can cause cardioplegic solution wash out, which in turn precipitates renewed electromechanical activity and the failure of perioperative heart protection [ 4 , 5 , 33, 34 ].…”