Effect of cardiac resynchronization therapy on longitudinal and circumferential left ventricular mechanics by velocity vector imaging: description and initial clinical application of a novel method using high-frame rate B-mode echocardiographic images.

Cardiac resynchronization therapy (CRT) has emerged as an important method to treat patient with symptomatic heart failure with evidence of intraventricular dyssynchrony. Tissue Doppler imaging by echocardiography has been shown to be an excellent tool for the assessment of mechanical left ventricular dyssynchrony and the selection of patients for CRT. However, there are some patients who do not show symptomatic improvement following CRT. One possible explanation for this is the need to optimize not only longitudinal synchrony, but also improve the circumferential and radial dynamics of the left ventricle. Doppler imaging does not allow reliable assessment of the latter because of the angle-dependency of the technique. Velocity Vector Imaging (VVI) is a newer technique which is angle-independent and thus provides an avenue to evaluate short-axis mechanics of the left ventricle. We describe a case in which VVI was used to assess the left ventricular dynamics in a patient with heart failure who did not respond to CRT.