Myocardial perfusion during warm antegrade and retrograde cardioplegia: a contrast echo study.

BACKGROUND: We evaluated distribution of warm antegrade and retrograde cardioplegia in patients undergoing coronary artery bypass grafting (CABG). METHODS: Myocardial perfusion was evaluated pre- and post-CABG using transesophageal echocardiography with injection of sonicated albumin microbubbles (Albunex) during warm antegrade and retrograde cardioplegia. The left ventricle (LV) was evaluated in five segments and the right ventricle (RV) was evaluated in two segments. Segmental contrast enhancement was graded as absent (score = 0), suboptimal or weak (score = 1), optimal or excellent (score = 2), or excessive (score = 3). RESULTS: Pre-CABG cardioplegic perfusion correlated weakly with severity of coronary artery stenoses (r = -0.331 and 0.276 for antegrade and retrograde cardioplegia, respectively). Antegrade cardioplegia administration resulted in 98% and 96% perfusion to the left ventricle pre- and post-CABG, respectively. Retrograde cardioplegic administration resulted in reduced LV perfusion, with 86% (p = 0.032 from antegrade) and 59% (p<0.001 from antegrade) pre- and post-CABG, respectively. The average LV perfusion score (mean +/- SEM) was greater with antegrade than retrograde cardioplegia both pre-CABG (1.93+/-0.04 vs. 1.53+/-0.11, p<0.001) and post-CABG (1.63+/-0.07 vs. 1.19+/-0.13, p = 0.004). RV perfusion was poor with both techniques pre-CABG, but improved significantly with antegrade cardioplegia post-CABG. CONCLUSIONS: We conclude that warm antegrade cardioplegia results in better left ventricular perfusion than warm retrograde cardioplegia. Right ventricular cardioplegic perfusion was suboptimal, but the best delivery was achieved with antegrade cardioplegia after coronary bypass. We therefore recommend construction of the saphenous vein graft to the right coronary artery early in the operative procedure.