[Hemolysis and platelet function in patients with prosthetic heart valves. Changes during exercise and with propranolol].

10 control subjects and 27 patients with prosthetic valves (15 with Björk aortic valves, 6 with mitral prostheses, 4 with aortic and mitral valves, 1 with a Björk mitral and a Starr aortic valve, and 1 with a Beall mitral valve) underwent, at intervals of 24 hours, two maximal exercise tests, initially without (day J) and subsequently with (day J + 2) propranolol in a dose of 80 mg/24 h, haemolysis and platelet function being assessed immediately before and immediately after each test. Exercise tolerance was not altered by propranolol in this dose, provided the heart size was not more than 1500 ml. Haemolysis, as assessed by the level of lactic dehydrogenase (LDH1) was increased by exercise, especially in the aortic prosthesis cases in which the LDH1 was increased by 21.6% (p less than 0.025). The increase was less marked under propranolol treatment, when it was 12.3% (p less than 0.05). Propranolol did not correct the platelet clumping caused by the prosthetic mitral valves, but did decrease platelet stickiness on exercise in the patients with prostheses (delta = -11.7%; p less than 0.05). Propranolol can not therefore be recommended for increased haemolysis if there is no demonstrable dysfunction of the prosthetic valve. Neither would we advise its use at present with the aim of reducing thrombotic accidents.