, Volume 16, Issue 6, pp 904-913,
Open Access This content is freely available online to anyone, anywhere at any time.
Date: 04 Sep 2009

The variable functional effects of the pacing site in normal and scarred ventricles



The pacing site has been shown to influence functional improvement with cardiac resynchronization therapy. We evaluated the effects of the pacing site on left ventricular (LV) function in an animal model.

Methods and Results

Equilibrium radionuclide angiography was acquired in sinus rhythm (NSR) and with ventricular pacing, from three pacing sites in seven normal and eight infarcted dogs. QRS duration, electrical activation pattern, wall motion, LV ejection fraction (EF), synchrony of ventricular contraction, and mean arterial pressure (MAP), were related to the pacing site and infarct size, during each of 120 episodes. Little changed during pacing in normals. In infarcted dogs, LV wall motion, and synchrony worsened, LVEF and MAP often fell. These changes related to altered activation patterns which were influenced by the pacing site but were not related to infarct size.


Hemodynamic and functional LV changes after infarction were found to vary with the pacing site and associated conduction and synchrony.
Supported by a Research Fellowship from the American Heart Association, California Affiliate.