Effects of Testosterone on Myocardial Repolarization

Overview

The main of the study is to evaluate the effect of testosterone on ventricular repolarization in patients with mild heart failure, at risk for sudden cardiac death. The electrocardiographic markers studied are QT variability index, the short term variability index.

Background: It has been widely demonstrated in experimental cardiology that estrogen may play a protective role on cardiovascular system, reducing myocardial damage in ischemia-reperfusion injury. Poor are the contributions of the effects of estrogen in the presence of testosterone which also showed potentially cardioprotective effects. Recently it has emerged strong evidence showing that the increase in the repolarization phase of myocardial duration and its temporal dispersion are predictive markers of cardiac death in post-ischemic dilated cardiomyopathy. In addition, the temporal dispersion of the final part of the repolarization phase (Tpeak-Tend) is specifically predictive for sudden cardiac death. In fact, the investigators propose the following plan of experimental study. It will be measured by the duration of the repolarization phase and its basal temporal dispersion and the peak of the heart rate obtained during stress test, in male subjects before and during testosterone replacement therapy. Patients evaluation baseline, after 1 month and after 6 months of follow up: Endocrinological evaluation with measurement of body weight, height, BMI calculation and (digital rectal examination) DRE, blood sample. Laboratory: Dosage of serum total testosterone, total and free PSA, blood count. Cardiological evaluation: 1. Patient's clinical objective examination: measurement of blood pressure and basal heart rate. 2. Traditional resting electrocardiogram 12-lead ECG in the supine position and 50 to 25 mm / sec, 10 millivolts. 3. Electrocardiographic single lead computerised registration (DI, D II and D III) of 5 minutes baseline and 5 minutes with controlled breathing (15 breaths / min), using the Spectralink 2011 program, which allows us to identify and calculate the variables object of this study; 4. Stress cycle electrocardiogram by modified Bruce protocol (25 watts every 2 minutes). The test is interrupted reaching 90% of the maximum heart rate, calculated based on the age of the patient, or to muscular exhaustion. A single lead electrocardiographic recording is started in the 10 minutes period after stress test, using Spectralink 2011 which allows investigators to calculate the variables studied. 5. trans thoracic echocardiogram with assessment of ejection fraction and any kinetic alterations in contractility and / or valvular heart disease, degree of possible diastolic dysfunction (E / A), size (interventricular septum, posterior wall, end-systolic and end-diastolic diameter in mm) and volumes (end-diastolic and end-systolic volume) of the left and right ventricle sections.

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