[Heart function and phonomechanocardiography (author's transl)]

The phonomechanocardiographic parameters most closely associated with heart failure are reviewed and a critical judgement is made of the method. The conclusion is drawn that phonomechanocardiographic measurements help to establish approximate limits of functional normality in cases of moderate abnormality. When acute phonomechanocardiographic alterations appear following infection or toxic heart disease or the use of potentially cardiotoxic drugs, the diagnosis of miocarditis can be made on an objective basis. To control the clinical course of heart failure the following parameters are useful: variations in the period of expulsion, "a" and "telediastolic" indices of the apexcardiogram, and the expulsion period/pre-expulsion period and expulsion period/systolic isovolumetric phase coefficients. Although phonomechancardiography lacks exact biological precision, it represents a rational and no invasive method for estimating heart function. It provides a means for recognizing diverse functional anomalies at their onset and for controlling their development. It thus helps in choosing adequate preventive and therapeutic measures to keep an early functional miocardial disease from becoming a serious case of heart failure.