[The dynamics of functional heart volumes in the descents of divers to depths of up to 15 m].

In an underwater environment at a depth up to 15 m the cardiodynamic parameters of resting and exercising man were recorded echocardiographically. Increased functional volumes of the heart and decreased ejection fraction (EF) have been noted. Underwater reactions of the cardiac functional volumes in response to exercise were characterized by: a maximum rise in systolic volume on exposure to low level loading; decreases of end diastolic and end systolic blood volumes; an elevation of EF lower than on the surface. With an increase in diving depth the functional reserves of the heart of exercising man are exhausted more rapidly.