Echocardiographic evaluation of regional mechanical dyssynchrony and candidates for cardiac resynchronization therapy

Biventricular pacemaker is a novel alternative approach in the management of patients with end-stage refractory heart failure. The fact that regional mechanical dyssynchrony is the major determinant in the selection of candidates for cardiac resynchronization therapy and that QRS duration is not a reliable marker of the regional mechanical dyssynchrony has expanded the role of echocardiography in this field. Echocardiography enables non-invasive quantification of both the hemodynamic status and regional left ventricular contractile function. Conventional echocardiography combined with two-dimensional and tissue Doppler modalities proved to be useful in the assessment of regional mechanical dyssynchrony and atrioventricular, interventricular, and intraventricular delays. Hence, echocardiography has become an indispensable imaging guide to cardiac resynchronization therapy for patient selection, evaluation of the response to resynchronization, and optimal lead localization.