Hemodynamic Benefits of Right Ventricular Outflow Tract Pacing: Comparison with Right Ventricular Apex Pacing

Abstract

To assess optimal hemodynamics in relation to stimulation site during right ventricular pacing, 17 consecutive patients who underwent cardiac catheterization were studied. In all patients, right ventricular apex and right ventricular outflow tract stimulation was performed at 85, 100, and 120 beats/min. Cardiac index at both pacing sites was compared using the left ventricular outflow tract continuous wave Doppler technique. Comparison of the two stimulation sites demonstrated that right ventricular outflow tract pacing resulted in a higher cardiac index at 85 beats/min (2.42 +/- 1.2 vs 2.04 +/- 1.0 L/min per m2, P < 0.002) at 100 beats/min (2.78 +/- 1.4 vs 2.35 +/- 1.1 L/min per m2, P < 0.001) and 120 beats/min (3.00 +/- 1.5 vs 2.61 +/- 0.9 L/min per m2, P < 0.001). From a total of 51 paired observations, 45 showed an increase in cardiac index during outflow tract pacing as compared to apex pacing. Right ventricular outflow tract pacing at 120 beats/min resulted in a lower cardiac index than right ventricular apex pacing in patients with significant coronary artery disease and/or impaired left ventricular function (ejection fraction < or = 50%), whereas right ventricular outflow tract pacing produced higher cardiac indices in the absence of these abnormalities. Right ventricular outflow tract pacing resulted in higher cardiac indices as compared to apex pacing in all other subgroups at all other pacing sites tested. It is concluded that stimulation of the right ventricular outflow tract offers a significant hemodynamic benefit during single chamber pacing as compared to conventional apex pacing, particularly in the absence of significant coronary artery disease and/or left ventricular dysfunction.

Short-Term Effects of Right-Left Heart Sequential Cardiac Resynchronization in Patients With Heart Failure, Chronic Atrial Fibrillation, and Atrioventricular Nodal Block

“…19 Several recent studies have suggested a potential advantage of using an alternative RV pacing site instead of the apex, specifically placement along the mid to upper infundibular tract. 20,21 In addition, some have suggested that simultaneous RV stimulation at both the apex and outflow tract can led to sufficient resynchronization effect to potentially obviate the need for an LV lead. 22 The latter hypothesis is particularly attractive given the complexity of LV lead placement.…”

Optimizing the pacing site in the ventricular septum by fluoroscopy and morphology of the paced QRS complex

“…Most short-term studies found significant differences in hemodynamic parameters in favor of the RVOT (ref. [5][6][7] ). Some studies, however, reported only insignificant positive hemodynamic changes 8,9 and also insignificant differences in functional performance in favor of the RVOT (ref.…”

Chronic Left Ventricular Pacing Preserves Left Ventricular Function in Children

“…Pacing at the His bundle is likely the superior approach [8], but appears to be technically difficult, especially in children. Right ventricle outflow tract pacing does not provide a consistent beneficial hemodynamic effect compared with RV apex pacing [6]. During pacing at different RV septal sites, hemodynamic function varies widely, and the location of the RV septal site that leads to the less pronounced decrease in pump function also varies between hearts in canine experiments [22].…”

“…However, RV apex pacing causes an acute decrease in left ventricular (LV) function in animals [26], adults [6] and children [14,36]. During chronic RV pacing in children, LV function, morphology [30,31], and histology [15] are at risk for deterioration over time (for review see Karpawich [16]).…”