Sum of effects of myocardial ischemia followed by electrically induced tachycardia on myocardial function.

Background: The alteration of contractile function after tachyarrhythmia ceases is influenced by the type of prior ischemia (acute coronary syndrome or ischemia inherent in a coronary revascularization procedure). We aimed to analyze cardiac dysfunction in an acute experimental model of supraphysiological heart rate preceded by different durations and types of ischemia.

Material And Methods: Twenty-four pigs were included in: (S1) series of ventricular pacing; (S2, A and B) series with 10 or 20 min, respectively, of coronary occlusion previous to ventricular pacing; S3 with 20 brief, repeated ischemia/reperfusion processes prior to ventricular pacing and; (S4) control series.

Experimental study of the so called left ventricular isovolumic relaxation phase.

Introduction And Objectives: Left ventricular filling begins in the ventricular isovolumic relaxation phase. According to the Torrent-Guasp myocardial band theory, this phase results from the contraction of the final portion of the myocardial band: the ascending segment of the apical loop. The objectives were to study the myocardial mechanisms influencing transmitral flow during early diastole and to determine whether the rapid ventricular filling phase involves contraction or relaxation.

Prevention of myocardial dysfunction by Eplerenon in experimental tachycardiomyopathy.

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/methods: 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).

Effect of short-duration electrically induced tachycardia on regional myocardial contractility.

Background: Tachycardia is a physiological mechanism for adapting cardiac output to modifications in energy consumption in the organism. The repercussions that short-duration tachycardia has on myocardial contractility have not been sufficiently studied.
To study the effects of short-duration tachycardia on regional myocardial function in the anterior face of the left ventricle depending on the rate, duration, and origin of the electrical stimulation producing the tachycardia.