Abstract
Objectives: To study the heart remodeling process in patients with thyro¬toxi¬co¬sis.
Materials and methods: Geometric parameters of the left ventricle (LV) and tissue characteristics at Doppler echocardiography (TDE) were compared in 27 women aged 53.3+-9.2 years with newly diagnosed moderate thyrotoxicosis in the absence of concomitant cardiac pathology and in 16 healthy subjects aged 45.1+-4.7 years. Initial clinical characteristics and those recorded in the gradually increasing treadmill workload test were analyzed.
Results: Remodeling in the relatively early period of thyrotoxicosis led to longitudinal and transverse reduction of the LV cavity and a decrease of the LV wall thickness without changes in LV sphericity and taper. The loss of body mass associated with a decreased heart size and lessened velocities of local heart wall movements, peak systolic and early diastolic motion of the mitral ring. The treadmill test showed an abrupt lowering of the physical stress tolerance threshold compared with the healthy subjects (57.8+-14.7 and 148.3+-11.7 Wt respectively). Six months after return to euthyroidism, the myocardial mass increased significantly parallel to a rise in the peak systolic and early diastolic velocity of mitral ring motion. Also, the linear size of LV tended to increase, and the functional cardiac reserve was twice the initial value (105 and 57 Wt respectively, р<0,001).
Conclusions: In spite of an absence of the reliable differences in the most of the LV geometry indicators, the functional reserve in the heart increased two times from an initial on eythyroidism reaching, but it was below the control level (148,3±11,7 Wt, р><0,05), what in definite conditions may determine the cardiac failure development in the future.