Mechanocardiography in evaluation of left ventricular function. Relevance of combined study of apex cardiogram and systolic time intervals in diagnosis of cardiomyopathies.

The study of left ventricular performance by means of systolic time intervals, especially represented by the PEP/LVET ratio and indices drawn from the first derivative of the apex cardiogram, makes possible a good approach to the functional anomalies of patients suffering from hypokinetic cardiomyopathies or hyperkinetic conditions of obstructive or unobstructive hypertrophic cardiomyopathies and of patients with hyperthyroid conditions. In hypokinetic states, the sensitivity and the specificity of the PEP/LVET ratio proved to be good, as was the case for indices taken from the first derivative of the apex cardiogram. However, the sensitivity and the specificity of the cardiogram were much better in the detection and evaluation of hyperkinetic conditions, hypertrophic cardiopathies or hyperthyroiditis. By providing the elements required for analysis of isometric contraction through indices drawn from the first derivative of the apex cardiogram and from the ejection phase, through the PEP/LVET ratio, and by adding exploitation of the diastolic phase, in particular through the A/H ratio exploring diastolic compliance, mechanocardiograms allow an all-round, quasi-physiopathological approach to disorders of left ventricular function during cardiomyopathies.