Evaluation of myocardial performance with conventional single-site ventricular pacing and biventricular pacing in a canine model of atrioventricular block.

Abstract

INTRODUCTION:

The aim of this study was to evaluate epicardial biventricular pacing as a means of maintaining synchronous ventricular activation in an acute canine model of AV block with normal ventricular anatomy and function. Chronic single-site ventricular pacing results in dyssynchronous ventricular activation and may contribute to ventricular dysfunction. Biventricular pacing has been used successfully in adult patients with congestive heart failure.

METHODS AND RESULTS:

This was an acute study of open chest mongrel dogs (n = 13). ECG, left ventricular (LV), aortic, and pulmonary arterial pressures were measured. LV impedance catheters were used to assess cardiodynamics using instantaneous LV pressure-volume relations (PVR). Following radiofrequency ablation of the AV node, a temporary pacemaker was programmed 10 beats/min above the intrinsic atrial rate, with an AV interval similar to the baseline intrinsic PR interval. The pacing protocol consisted of 5-minute intervals with the following lead configurations: right atrium-right ventricular apex (RA-RVA), RA-LV apex (LVA), and RA-biventricular using combinations of four ventricular sites (RVA, RV outflow tract [RVOT], LVA, LV base [LVB]). RA-RVA was used as the experimental control. LV systolic mechanics, as measured by the slope of the end-systolic (Ees) PVR (ESPVR, mmHg/cc), was statistically greater (P < 0.05) with all modes of biventricular pacing (RA-RVA/LVA 20.0 +/- 2.9, RA-RVA/LVB 18.4 +/- 2.9, RA-RVOT/LVA 15.1 +/- 1.8, RA-RVOT/LVB 17.6 +/- 2.9) compared to single-site ventricular pacing (RA-RVA 12.8 +/- 1.6). Concurrent with this improvement in myocardial performance was a shortening of the QRS duration (RA-RVA 97.7 +/- 2.9 vs RA-RVA/LVA 75.7 +/- 4.9, RA-RVA/LVB 70.3 +/- 4.9, RA-RVOT/LVA 65.3 +/- 4.4, and RA-RVOT/LVB 76.7 +/- 5.9, P < 0.05).

CONCLUSION:

In this acute canine model of AV block, QRS duration shortened and LV performance improved with epicardial biventricular pacing compared to standard single-site ventricular pacing.

• Authors: Patricio A Frias, Joel S Corvera, Laura Schmarkey, Margaret Strieper, Robert M Campbell, Jakob Vinten-Johansen
• Journal: Journal of cardiovascular electrophysiology (J Cardiovasc Electrophysiol) Vol. 14 Issue 9 Pg. 996-1000 (Sep 2003) ISSN: 1045-3873 [Print] United States
• PMID: 12950546 (Publication Type: Comparative Study, Journal Article, Research Support, Non-U.S. Gov't)

Topics

• Animals
• Aorta (physiopathology)
• Blood Volume
• Cardiac Pacing, Artificial (methods)
• Catheter Ablation
• Dogs
• Electrocardiography
• Heart (physiopathology)
• Heart Block (physiopathology, surgery)
• Pressure
• Pulmonary Artery (physiopathology)
• Time Factors
• Ventricular Function, Left