Abstract
Cardiac resynchronization therapy is effective in patients with a low ejection fraction and left bundle branch block, but 20%–30% do not respond despite selection of the optimal site for pacing on the left ventricle. We investigated whether optimizing the site for placement of the pacing lead on the right ventricle could further improve left ventricular function during cardiac resynchronization in 19 patients (mean age, 63 ± 5 years) undergoing coronary artery bypass with post-ischemic dilated myocardiopathy (ejection fraction, 25.8% ± 2%) and left bundle branch block. The hemodynamic response to pacing was tested with the right ventricular lead positioned at the interventricular septum, atrioventricular junction, acute margin, and the pulmonary trunk. Biventricular stimulation improved left ventricular function. When the right ventricular lead was sited at the interventricular septum, a significant improvement in all hemodynamic parameters compared to the other sites was obtained. Biventricular pacing is important to optimize cardiac resynchronization. Although further studies are needed to confirm these findings, accurate lead placement is recommended for cardiac resynchronization therapy in patients with poor cardiac function and left bundle branch block.
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