Key result
In infarcted dogs, left ventricular apical pacing significantly reduced left ventricular ejection fraction to 35.8% compared to sinus rhythm, accompanied by worsened wall motion and synchrony.
Why the study?
Does the pacing site affect left ventricular function and synchrony in normal and infarcted ventricles?
Does the pacing site affect left ventricular function and synchrony in normal and infarcted ventricles?
The pacing site significantly influences left ventricular function and synchrony, particularly in scarred ventricles, highlighting the importance of optimal lead placement in cardiac resynchronization therapy.
Answers are grounded in this paper and cite their sources.
Apical pacing may impair LV function in infarcted hearts; hypothesis-generating for optimal lead placement in CRT.
BACKGROUND: 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. CONCLUSIONS: Hemodynamic and functional LV changes after infarction were found to vary with the pacing site and associated conduction and synchrony.
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Romeral et al. (2009) studied Myocardial infarction (animal model) (n=15). Ventricular pacing from different sites (high septum, right ventricular free wall, left ventricular apex) vs. Normal sinus rhythm was evaluated on Left ventricular ejection fraction (LVEF) in infarcted dogs (p=<0.01). In infarcted dogs, left ventricular apical pacing significantly reduced left ventricular ejection fraction to 35.8% compared to sinus rhythm, accompanied by worsened wall motion and synchrony.
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