Effect of collateral blood flow on cardioplegia distribution in patients with an occluded right coronary artery

Introduction. The distribution of cardioplegia to the myocardium is a predictor of immediate recovery of ventricular function after cardiopulmonary bypass (CPB). An occluded right coronary artery (RCA) can impede antegrade cardioplegia (ACP) delivery to the right ventricle (RV), and the delivery of retrograde cardioplegia (RCP) to the RV is not always predictable. Adequate protection of the RV can therefore be challenging. We used myocardial contrast echocardiography (MCE) to assess the effect of collateral blood flow on the distribution of ACP and RCP in patients with an occluded RCA. Methods. Following institutional approval and informed consent, 15 patients were studied during CABG surgery. Moderate hypothermic CPB was instituted in the routine manner. ACP and RCP catheters were placed. A long-axis TEE view was monitored (5MHz probe, HP, Andover, MA). While ACP was being given, 4cc of Albunex™ (Mallinckrodt Medical, St. Louis, MO), an albumin-based contrast agent, was given through the antegrade cannula. Similarly, Albunex was also given during the subsequent RCP. Contrast-enhanced perfusion images were obtained during cardioplegia delivery. Contrast enhancement was judged by a trained observer in 3 areas: apex, septum, and RV free-wall. Results. There was a total of 30 contrast injections. I Septum I APEX I RV I CE NCE TD CE NCE TD CE NCE TD RCP 10 0 5 10 0 5 6 2 7 ACP 9 3 3 8 3 4 3 6 6 CE = contrast enhancement; NCE = no contrast enhancement; TD = could not determine contrast distribution because of technical difficulty/limitations. Discussion. The mechanism of RV free-wall protection in patients with an occluded RCA is unpredictable. Antegrade protection may occur due to well-developed collateral vessels, whereas retrograde protection is not always successful. MCE is useful in patients with a RCA occlusion to define the best cardioplegic strategy. The surgical strategy may need to be modified to ensure early revascularization of the area supplied by the RCA.

Duke Scholars

Author Solomon Aronson Anesthesiology, Cardiothoracic