Abstract

Background
High-rate short-duration ventricular pacing induces myocardial hypokinesis that persists once the hemodynamic conditions have been recovered. The aim was to study the factors that determine the persistence of myocardial dysfunction when ventricular tachycardia has ceased and hemodynamic conditions have been restored.
Material and Method
An in vivo experimental pig model was used consisting of a ventricular pacing series (n=10), a ventricular pacing and aldosterone blockade (eplerenon) series (n=6), and a control series without ventricular pacing (n=6). Electrical stimulation was performed from the epicardial base of the left ventricle at a frequency 60% above the basal rate for 2 hours followed by a recovery period of 60 minutes. Cardiac and myocardial function parameters were studied. Plasma levels of aldosterone, renin activity, and glutathione were measured.
Results
Electrically induced tachycardia produced hemodynamic and myocardial changes that persisted after stimulation had ceased, accompanied by an increase in aldosterone and a coronary flow decrease. These changes were not seen when aldosterone activity was blocked by eplerenon. There was a non-significant elevation in glutathione levels.
Conclusions
These data show that although participation of other neurohormones cannot be ruled out, aldosterone blockade (eplerenon) ameliorates myocardial dysfunction persisting after ventricular tachycardia by preventing coronary endothelial dysfunction.

Keywords: Spironolactone - therapeutic use, Swine, Mineralocorticoid Receptor Antagonists - therapeutic use, Tachycardia - physiopathology, Cardiomyopathies - prevention & control