George Kottis

Effect of dobutamine combined with intra-aortic balloon counterpulsation on left ventricular function early after acute myocardial infarction: experimental study.

Acute myocardial infarction (AMI) causes left ventricular (LV) remodeling, which forms the substrate for its early and late complications. The purpose of this study was to compare the acute effect of dobutamine or intra-aortic balloon pumping (IABP), alone or in combination, on LV function in the early phase of an experimental AMI. In 18 pigs, AMI was induced by ligation of the left anterior descending artery (LAD). IABP or dobutamine infusion at a rate of 5 µg/kg/min, or a combination of the two, was applied immediately after ligation of the LAD. Echocardiographic measurements of the long and short LV axes were obtained before (baseline) and post LAD ligation and at the end of each intervention for 5, 15, and 30 min. The fractional shortening (FS) of both axes, as well as the ejection fraction (EF), was calculated. The combination of dobutamine with IABP increased the EF significantly after the AMI in comparison to dobutamine or IABP alone, and improved the stroke volume, cardiac output, and long axis FS in comparison to IABP alone. Dobutamine alone produced a significantly higher increase of EF in comparison to IABP alone. These results indicate that the combination of dobutamine with IABP may be useful during AMI.

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.

Atrioventricular Left Ventricular Apical Pacing Improves Haemodynamic, Rotational, and Deformation Variables in Comparison to Pacing at the Lateral Wall in Intact Myocardium: Experimental Study

Aim. To assess the effect on left ventricular (LV) function of atrioventricular (AV) and ventricular pacing at the LV apical or lateral wall and to compare the normal torsional and deformation pattern of the intact LV myocardium with those created by the aforementioned LV pacing modes and sites. Methods. Experiments were conducted in pigs (n = 21) with normal LV function to investigate the acute hemodynamic effects of epicardial AV and ventricular LV pacing at the LV apical or lateral wall. Torsional and deformation indices of LV function were assessed using speckle tracking echocardiography. Results. AV pacing at the apex revealed a significant reduction in the radial strain of the base (P < 0.03), without affecting significantly the ejection fraction and the LV torsion or twist. In contrast, AV pacing at the lateral wall produced, in addition to the reduction of the radial strain of the base (P < 0.01), significant reduction of the circumferential and the radial strain of the apex (both P < 0.01) as well as of the ejection fraction (P < 0.002) and twist (P < 0.05). Conclusions. In pig hearts with intact myocardium, LV function is maintained at sinus rhythm level when AV pacing is performed at the LV apex.