Changes in coronary blood flow and myocardial metabolism during aortic balloon valvuloplasty

Abstract

The effects of balloon inflation on myocardial perfusion and metabolism were studied during aortic valvuloplasty in 17 patients with aortic stenosis, including 6 with associated coronary artery disease. Coronary sinus flow and blood samples were obtained before and during the first inflation, and 5 to 10 minutes after the last inflation. During inflation, coronary blood flow decreased (272 ± 111 standard deviation to 166 ± 92 ml/min; p < 0.05), myocardial oxygen uptake fell and transcardiac lactate handling shifted from extraction to production (35 ± 54 to −41 ± 48 μmol/min; P < 0.01). At the end of the procedure, aortic valve area had increased from 0.51 ± 0.22 to 0.81 ± 0.48 cm 2 (p < 0.002). Coronary sinus flow increased slightly above control values (+6%; difference not significant) and myocardial oxygen and lactate uptakes were back to control values. However, myocardial alanine production had increased from −3.6 to −6.6 μmol/min (p < 0.05) and glutamine production was reduced or replaced by extraction (−3.3 ± 2.1 to 3.5 ± 3.8 μmol/min; p < 0.05). Recovery of coronary flow, oxygen and lactate uptakes was not significantly different in patients with or without coronary artery disease, although the former patients tended to have less glutamine extraction and less improvement in their ejection fraction at the end of the procedure. Thus, aortic balloon valvuloplasty produces brief episodes of low-flow ischemia. Recovery of oxidative metabolism is almost immediate after deflation and no detrimental effect seems to persist at the end of the procedure. These data show not only the relative safety of this procedure but also its potential as a model to improve our understanding of the pathophysiology of low-flow ischemia.