Normothermic retrograde cardioplegia is effective in patients with left ventricular hypertrophy. A prospective and randomized study.

Abstract

Twenty patients with left ventricular hypertrophy (LVH) undergoing isolated aortic valve replacement were prospectively randomized to receive either continuous retrograde normothermic (n = 8) or intermittent retrograde hypothermic (n = 12) methods of myocardial protection. Biopsies of the left ventricular septum were evaluated for ultrastructure and assayed for ATP. There was no mortality, no requirement for intra-aortic balloon pump nor neurological events in any of the patients from either group. Myocardial ATP (warm 23.2 +/- 1.8 nmol/mg protein; cold 22.4 +/- 1.2 nmol/mg protein; p = 0.72) and myocardial CPK-MB (warm 43.6 +/- 5.2 U/l; cold 39.0 +/- 2.5 U/l; p = 0.67) were not significantly different. Ultrastructure was generally well preserved in the biopsies from both groups, with the exception of one patient in the normothermic group. Systemic lactate sampled after 40 minutes of cardiopulmonary bypass was significantly higher in the normothermic group (warm 3.4 +/- 0.27 mmol/l; cold 2.3 +/- 0.21 mmol/l; p = 0.01), however, the myocardial lactate production was not significantly different between the two groups (extraction ratio; warm 0.01 +/- 0.3; cold 0.13 +/- 0.1; p = 0.45). We conclude that the continuous normothermic retrograde method of myocardial protection is effective in patients with left ventricular hypertrophy; however, the higher systemic lactate levels using this technique raises concerns regarding the adequacy of systemic perfusion at 37 degrees C.