[Contractile myocardial proteins in patients with acquired heart defects].

The ATP-ase activity of myosin; the level of SH-groups and the concentration of myosin were studied in various clinical groups of patients with mitral, mitral-aortic and mitral-aortic-tricuspid valve defects. Proceeding from the duration of the history of the disease, the mitral cases were grouped in the following way: Group 1 -- heart disease of under 10-years duration; Group 2 -- under 20 years; Group 3 -- over 20 years; Group 4 -- three patients with combined heart diseases; Group 5 -- four lethal cases due to postoperative cardiovascular failure. The papillary muscle was taken for biochemical tests in all surgical procedures for mitral valve replacement. The conducted investigations demonstrated that the ATP-ase activity of myosin was the lowest in those dying after surgery of cardiovascular failure. The earliest sign of the deteriorating structure of the contractile proteins in lasting mitral heart disease is the growing content of thiol compounds of myosin.