NORMOTHERMIC RETROGRADE CARDIOPLEGIA IS EFFECTIVE INPATIENTS WITH LEFT-VENTRICULAR HYPERTROPHY - A PROSPECTIVE AND RANDOMIZED STUDY

Twenty patients with left ventricular hypertrophy (LVH) undergoing iso lated aortic valve replacement were prospectively randomized to receiv e either continuous retrograde normothermic (n = 8) or intermittent re trograde hypothermic (n = 12) methods of myocardial protection. Biopsi es of the left ventricular septum were evaluated for ultrastructure an d assayed for ATP. There was no mortality, no requirement for intra-ao rtic 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 significantl y different. Ultrastructure was generally well preserved in the biopsi es from both groups, with the exception of one patient in the normothe rmic group. Systemic lactate sampled after 40 minutes of cardiopulmona ry 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 my ocardial lactate production was not significantly different between th e two groups (extraction ratio: warm 0.01 +/- 0.3; cold 0.13 +/- 0.1; p = 0.45). We conclude that the continuous normothermic retrograde met hod of myocardial protection is effective in patients with left ventri cular hypertrophy; however, the higher systemic lactate levels using t his technique raises concerns regarding the adequacy of systemic perfu sion at 37 degrees C.