Rick Schreurs

43 Cardiac pacing in first degree AV-block Figure 1. Schematic representation of the animal experimental set-up. (A) Overview of the porcine model. Pacemaker leads were transvenously inserted in the right atrial (RA) appendage and right ventricular (RV) apex and attached to the left ventricular (LV) epicardium. Complete atrioventricular (AV)-block was created by radiofrequency ablation of the AV-node. LV pressure and volume were measured using a conductance catheter and RV and left atrial (LA) pressure were measured using a cathetertip manometer. (B) Signal analysis. The first derivative of LV volume was used to calculate forward flow over the mitral valve (grey area under E- and A-wave) and diastolic mitral regurgitation (MR, yellow area). The integral of aortic flow, measured by a flow probe, was used to quantify forward stroke volume and cardiac output (red area). Statistical analysis of clinical and experimental study Statistical analysis was performed using Statistical Package for Social Sciences version 24.0 (SPSS Inc., Chicago, Illinois, USA). Continuous data are presented as mean ± standard deviation (SD). The relative change of the hemodynamic variables at various AV-delays were evaluated using a one-way repeated measures ANOVA. If significant, a Student’s paired samples T-test and Bonferroni correction was used to test significance of the change at individual AV-delays. To evaluate differences between different pacing modes, two-way ANOVA for repeated measurements was used, followed by Student’s paired samples T-test. A two-sided probability value of <0.05 was considered statistically significant. 3