Myocardial Effects of Type 2 Diabetes, Co-morbidities, and Changing Loading Conditions : a Clinical Study by Tissue Velocity Echocardiography
Abstract: Ever since the validation of the tissue velocity echocardiography (TVE) technique more than a decade ago the modality has been used rather successfully in various clinical situations, at rest as well as during stress echocardiography. Hitherto, dobutamine stress echocardiography has been the hallmark of all forms of stress procedures, now with TVE, quantification of the longitudinal motions of the left ventricle shows far superiority, with improved sensitivity and specificity in the functional diagnosis of coronary artery disease. Morever there has been continued interest in this technique for even assessing subclinical myocardial systolic and diastolic function in clinical scenarios like diabetes, hypertension and chronic kidney disease. The aim of the present study was to evaluate left ventricular myocardial functions by applying TVE in human subjects having type 2 diabetes with or without co-morbidities and during changing loading conditions. The effects of changing loading conditions were analyzed during hemodialysis and following oral administration of an AT1 receptor blocker. The studied subjects included individuals with diabetes as well as those with associated hypertension, coronary artery disease, microalbuminuria and end-stage renal disease. All patients with type 2 diabetes and co-morbidities underwent TVE enhanced dobutamine stress echocardiography while load dependant left ventricular functions were analyzed at rest. There were 270 subjects in the study of type 2 diabetes and associated cardiovascular diseases and 101 subjects in the study of changing loading conditions. Patients with type 2 diabetes revealed subclinical left ventricular dysfunction characterized by reduced functional reserve. This influence becomes quantitatively more pronounced in the presence of coexistent coronary artery disease and hypertension. The coexistence of type 2 diabetes and hypertension appears to have additive negative effect on both systolic and diastolic left ventricular function, even in the absence of coronary artery disease. The presence of microalbuminuria in type 2 diabetes patients does not worsen diminished myocardial functional reserve. A single session of hemodialysis improves left ventricular function in patients with end-stage renal disease only in the absence of type 2 diabetes and co-morbidities, while a single dose of an AT1 receptor blocker valsartan results in reduction of afterload and, subsequently, in improvement of left ventricular function. TVE appears to be a sensitive tool for objective assessment of left ventricular function and can be successfully applied for the clinical evaluation of the effect of type 2 diabetes and co-morbidities on myocardial performance.
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