Acute Hemodynamic Effects of Atrioventricular Pacing at Differing Sites in the Right Ventricle Individually and Simultaneously

Abstract

We hypothesized that pacing, which provided a rapid uniform contraction of the ventricles with a narrower QRS, would produce a better stroke volume and cardiac output (CO). We sought to study whether pacing simultaneously at two sites in the right ventricle (right ventricular apex and outflow tract) would provide a narrower QRS and improved CO in 11 patients undergoing elective electrophysiology studies. Patients were studied by transthoracic echocardiography measurement of CO using the Doppler flow velocity method in normal sinus rhythm, AOO pacing (rate 80), DOO pacing in the right ventricular apex (AV delay 100 ms), DOO pacing in the right ventricular outflow tract, and DOO pacing at both right ventricular sites simultaneously in random order. The COs were 5.42 +/- 1.83, 5.61 +/- 1.97, 5.67 +/- 1.6, 5.84 +/- 1.68, and 5.86 +/- 1.52 L/min, respectively (no significant difference by repeated measures analysis of variance [ANOVA]). The QRS durations were 0.09 +/- 0.02, 0.09 +/- 0.02, 0.13 +/- 0.027, 0.13 +/- 0.03, and 0.11 +/- 0.03 secs respectively. Repeated measures ANOVA showed that the QRS duration significantly increased with right ventricular apex or right ventricular outflow tract pacing compared to sinus rhythm and AOO pacing (P < 0.001) but then diminished with pacing at both sites (P < 0.01). QRS duration was not correlated with CO, however the change in QRS duration correlated significantly with the change in CO when pacing was performed at the two right ventricular sites simultaneously. In conclusion, during DOO pacing, there was a trend for pacing in the right ventricular outflow tract or both sites to improve the CO compared to the right ventricular apex. With simultaneous pacing at both ventricular sites, the QRS narrowed. Further studies will be required to see if this approach has value in patients with poor left ventricular function or congestive heart failure.

Atrium-driven Mitral Annulus Motion Velocity Reflects Global Left Ventricular Function and Pulmonary Congestion During Acute Biventricular Pacing

“…This is in accordance with previous reports of acute biventricular pacing in which the QRS width did not reflect any improvement in the LV performance and cardiac output. 34,35 Saxon et al 33 could not find a significant difference in QRS duration between the paced QRS complexes achieved with intraoperative simultaneous RV and LV pacing and the native QRS duration. It is increasingly recognized that identification of candidates for biventricular pacing solely on the basis of QRS duration, which is only a surrogate parameter of electromechanical dyssynchrony, is inadequate, whereas inclusion of some direct measurements of inter-or intraventricular dyssynchrony by echocardiography may be helpful in identifying potential long-term responders.…”

Right ventricular bifocal stimulation in the treatment of dilated cardiomyopathy with heart failure

“…Because short AV delay was not clearly useful in the treatment of the heart failure, a greater interest exists in "ventricular resynchronization" 4 .…”

Selective site ventricular pacing

“…This does not necessarily translate, however, into shorter total ventricular activation time, as manifest by QRS duration. Data are conflicting on the effect of RVOT pacing on QRS duration compared with apical pacing, with several studies demonstrating no significant difference in QRS duration [33][34][35][36][37][38][39][40][41], whereas others have shown a small, but significant, shortening of QRS duration [42][43][44], although all remained prolonged at greater than 120 ms. Data on paced QRS duration can be found in Tables 1 and 2.…”