Hemodynamic Effects of Left Ventricular Pacing Site in an Animal Model of Heart Failure

Abstract BACKGROUND: This study investigates how different left ventricular epicardial and endocardial pacing sites influence hemodynamic performance in an animal model of heart failure (HF). METHODS: In six adult sheep, dilated HF was induced by rapid pacing. Subsequently, endocardial left ventricular stimulation was performed using a 64-electrode basket catheter. Epicardial pacing was achieved with temporary electrodes. RESULTS: Baseline cardiac output (CO) was 2.7 ± 0.4 l/min and improved significantly with lateral wall epicardial and endocardial stimulation (3.6 ± 0.7 and 3.8 ± 0.65 l/min), whereas right ventricular pacing led to lower CO (2.1 ± 0.5 and 2.0 ± 0.9 l/min). In the optimal pacing location arterial pressure, pulmonary capillary wedge pressure (pcwp) and LV diameters improved significantly. Right ventricular pacing impaired hemodynamics, while no change was observed in the LV inferior wall and apex pacing. CONCLUSION: Endocardial and epicardial pacing of the lateral wall led to an improvement in LV function while right ventricular pacing induced a further reduction of LV performance. As this optimal pacing site cannot always be reached via the coronary sinus, surgical implantation of epicardial electrodes should be considered in all non-responding patients.