Effect of early changes in functional geometry of left ventricular contraction on the development of ventricular fibrillation during acute myocardial ischaemia. An experimental study.

Objective: The early appearance of ventricular fibrillation (VF) following acute myocardial infarction (MI) is associated with adrenergic effects and electrical interactions although some early "mechanical" changes may also occur. The aim of the present experimental study was to examine whether early changes in the functional geometry of left ventricular (LV) contraction may be associated with ventricular arrhythmias occurring during the first 120min of MI.

Methods: In 11 swine left anterior descending (LAD) coronary artery ligation was performed.

Pacing within the ischemic area significantly decreases the left ventricular ejection fraction during experimental acute myocardial infarction.

Background: The aim of this study was to examine the effects on left ventricular (LV) function of LV apical or/and lateral wall pacing during an experimental acute myocardial infarction.

Methods: In 12 anesthetized pigs, epicardial LV pacing at the apex or lateral wall, or at both sites simultaneously, was performed before and after left anterior descending (LAD) ligation. Data concerning LV function were obtained by two-dimensional echo during spontaneous sinus rhythm (SR) and during pacing before and 15, 45, 60, and 90 minutes after LAD ligation.

The association of coronary flow changes and inflammatory indices to ischaemia-reperfusion microvascular damage and left ventricular remodelling.

Background: The aim of this study was to investigate the effect of coronary flow (CF) changes and inflammatory indices on myocardial microcirculation--assessed by myocardial contrast echocardiography (MCE)--and on left ventricular remodelling, in an experimental ischaemia-reperfusion model.

Methods: In 15 pigs, weighing 30 +/- 5 kg, ligation of the left anterior descending (LAD) coronary artery was performed, followed by reperfusion for 120 min. Peak, mean, duration and volume of systolic and diastolic components of CF distal to the LAD ligation were measured using a butterfly flowmeter and their ratio was calculated.

The acute effect of an echo-contrast agent on right ventricular dimensions and contractility in pigs.

Background: : The aim of the present study was to examine the effect of the second-generation ultrasound contrast agent (2nd GUCA) SonoVue on right ventricular (RV) dimensions and contractility and to investigate whether a dose-related interaction exists between the contrast agent and RV function.

Methods: : Twenty-eight pigs were randomly assigned to 3 groups for intravenous administration: a low-dose group (0.5 cc of SonoVue), a high-dose group (1 cc of SonoVue), and a control group (2 cc of normal saline).

Preservation of coronary sinus flow after complete ligation of all coronary arteries.

Introduction: The contribution of the collateral network to myocardial oxygenation under normal circumstances is not clear. However, it is possible that in diseased myocardium this network may be activated and contributes significantly to cardiac blood supply. The purpose of this study was to examine the coronary sinus flow after acute, synchronous, complete occlusion of all epicardial coronary arteries and to investigate methods to increase the flow in the setting of ischaemia.

Effect of dobutamine on left ventricular functional geometry after acute myocardial infarction: experimental study.

Introduction: Acute myocardial infarction causes left ventricular (LV) remodelling, which forms the substrate for its early and late complications. The aim of this experimental study was to evaluate the acute changes in LV functional geometry after acute myocardial infarction using echocardiography and to investigate the effect of continuous intravenous dobutamine administration on those changes.

Methods: In 22 pigs acute myocardial infarction was induced by ligation of the anterior descending branch of the left coronary artery.