New echocardiographic techniques in the evaluation of left ventricular mechanics in subclinical thyroid dysfunction.

The new echocardiographic techniques for the study of physiopathological intramyocardial phenomena include video densitometry (VD), integrated backscatter (IBS), and color Doppler myocardial imaging (CDMI). Being more independent from cardiac load and from rotational and translational heart motion, these new sensible, noninvasive techniques such as CDMI and IBS show a real incremental value in comparison with conventional echocardiography and allow to detect subtle functional and textural abnormalities of intramural myocardium, partially undetectable by conventional two-dimensional Doppler echocardiography. Subclinical thyroid dysfunction (STD), both in its hypo- and hyperthyroidism form, has a relatively high prevalence in general population (9-15% with a lower percentage of adult males), hence it could be very useful to study more deeply heart involvement in these physiopathological conditions and understand the complex relationship between thyroid and heart. The use of these new ultrasonic techniques in subclinical hypothyroidism helps to detect the early simultaneous involvement of both cardiac cycle phases, which causes a decrease of intramyocardial contractility and an impairment of both active and passive phases of diastole. In subclinical hyperthyroidism, these new ultrasonic techniques permitted to discover more complex and different early cardiac abnormalities of both systolic and diastolic phases.