[Heart insufficiency. Physiology and physiopathology of muscle contraction of the heart].

To understand physiopathology of contractibility in heart failure is needed the previous knowledge of normal muscle contractibility, calcium regulation, methods of assessment of isolated cardiac muscle and in situ heart contraction. Models of calcium movements during rest and contraction are presented and concepts of preload, afterload, Vmax and Po introduced. The importance of assessment of cardiac diastolic function is referred. Biochemical alterations in the failing myocardium are presented.