[Phonomechanographic evaluation of left ventricular function in hyperthyroid states].

Hyperthyroidism is associated with a hyperkinetic syndrome, the mechanisms of which are not fully understood but which include an increase in heart rate, a reduction in systemic arterial resistance and a debatable increase in myocardial contractility. The limitations of radioimmunological assay of the hormonal mediators underline the diagnostic value of an atraumatic method of quantifying left ventricular systolic function. In view of the variable sensitivity of phonomechanographic and echocardiographic indices with respect to changes in heart rate, pre- and after load, we studied apex cardiographic indices during the phase of isovolumetric contraction. Fifty-eight patients with hyperthyroidism but without patent cardiovascular disease were divided into two subgroups: Grave's disease: 38 cases, and toxic adenoma: 22 cases. The results of the measurements of systolic time intervals and the calculation of "indices of contractility" obtained from the apex cardiogram and its first derivative, were compared with those of 36 young, normal subjects. The results show that: the pre-ejection period of the study population was much shorter than normal (65,7 ms +/- 2,5 vs 84,6 ms +/- 3,4; p less than 0,001); this was clearly related to the chronotropic factor (p less than 0,05). The pre-ejection/ejection period ratio did not differentiate hyperthyroid from normal subjects (0,265 vs 0,283, p greater than 0,20), except in Graves' disease (0,249, p less than 0,02). On the other hand, measurements made from the apex cardiogram showed significant differences in both types of hyperthyroidism. (Formula: see text). In conclusion, phonomechanography may be used to quantify the increase in left ventricular function in hyperthyroidism.(ABSTRACT TRUNCATED AT 250 WORDS)