Effects of Proximal Ventricular Septal Pacing on Hemodynamics and Ventricular Activation

Abstract

Recently the use of alternate site pacing to improve cardiac function in patients with bradyarrhythmias has increased. In the present study, hemodynamics of right ventricular septal pacing were studied in seven dogs. A bipolar screw-in lead and endocardial lead were placed in the proximal right ventricular septum and right ventricular apex, respectively. The right ventricle was paced from each site. A conductance catheter and Millar catheter were inserted into the left ventricle to determine the left ventricular pressure and the pressure-volume loop. Cardiac output was measured using the thermodilution method. In five of the seven dogs, ventricular activation was documented by isochronal epicardial activation mapping during each pacing mode. Mean arterial pressure and cardiac output during septal pacing were significantly higher than during apical pacing (110 +/- 17 mmHg vs 100 +/- 18 mmHg; 1.00 +/- 0.39 L/min vs 0.89 +/- 0.33 L/min). The positive dp/dt during septal pacing was significantly higher than during apical pacing (2137 +/- 535 mmHg/s vs 1911 +/- 404 mmHg/s). End-systolic elastance during septal pacing was significantly higher compared to apical pacing (13.1 +/- 0.3 mmHg/mL vs 8.9 +/- 4.0 mmHg/mL). The ventricular activation time during septal pacing was significantly shorter than during apical pacing. The epicardial maps generated during septal pacing were similar to those from atrial pacing. We conclude that hemodynamics and interventricular conduction are less disturbed by proximal right ventricular septal pacing than apical pacing in dogs with normal hearts.

Upgrading Pacemaker Patients with Right Ventricular Apical Pacing to Right Ventricular Septal Pacing Improves Left Ventricular Performance and Functional Capacity

“…RV septal pacing is a more simple and feasible alternative permanent pacing site than LV‐based or biventricular pacing in patients with bradycardia 3 . Experimental studies 19–21 demonstrate that pacing at RV septal sites that are closer to the proximal portion of His bundle resulted in a shorter LV activation time and induced lesser disturbances on LV performances and structures. Furthermore, recent clinical studies 7,22–25 also suggest that pacing in the midseptal region of RV may lead to a lesser degree of abnormal LV electrical and mechanical activation, and thus can potentially avoid the adverse effects on LV function related to permanent RV apical pacing.…”

Upgrade to biventricular pacing in patients with pacing-induced heart failure: can resynchronization do the trick?

“…The differential effects of alternative RV pacing sites on QRS duration and ventricular systolic function have been studied in the past: Takagi et al 39 showed in a normal heart canine model that haemodynamics and interventricular conduction are less disturbed by proximal RV septal pacing than apical pacing. In contrast, Peschar et al 40 have demonstrated, also using a normal heart canine model, that although septal or apical LV pacing did not affect LV systolic function, RV septal pacing was not superior to RV apical pacing.…”

Sequential deformation and physiological considerations in unipolar right or left ventricular pacing

“…This observation has led to development of alternate pacing sites (right ventricular outflow tract (RVOT) or left ventricular (LV)) for electrical stimulation in patients with heart block and/or bradycardia [2], especially when congestive heart failure is present [5,6]. In spite of progress in evaluating myocardial function at the hemodynamic and electrophysiological levels [7][8][9], the influence of different pacing sites on the organized synchrony of contraction has not yet been defined.…”