[Protection of the myocardium by hypothermia during extracorporeal circulation. Experimental and clinical study]

Hypothermic protection of myocardia during E.C.C. has been estimated on a 35 dogs experimental series and on a clinical series of 700 acquired cardiopathies of adult, including 400 valvular replacements and 300 aorto-coronary by-pass. Experimental results have been estimated by biochemic and morphologic controls done on myocardic samples took up by drillbiopsy. The biochemical study includes among others a dosing of the high-energy phosphorus compounds (P.C. and A.T.P.). Morphological study was done by optic and electronic microscopy. Results made clear the superiority of the hypothermic ischemia at 10 degrees C on the continued perfusion at 32 degrees C with fibrillative heart. An hypothermic protection method with successively cold perfusion of the coronary system and a heart immersion in a salted solution at 4 degrees C has been utilized during valvular and coronary surgery on human in 700 cases. The total mortality was of 5,8 p. 100. The rate of post-operative infarcts was 2,4 p. 100. Incidence of intra-ventricular conduction troubles has been 1,1 p. 100. There was no relation between mortality and morbidity of myocardic origin and the lasting of the ischemic clamp, which were of 21 mn up to 165 mn. The low incidence of complications of myocardic origin is due to the hypothermic protection of the myocardia.