Cardiac resynchronization therapy: Biventricular pacing for heart failure

Heart failure is a chronic progressive syndrome, which impairs quality of life and is associated with frequent hospitalizations and a high mortality rate despite optimal medical therapy. Ventricular dyssynchrony is characteristic of systolic heart failure in some of the patients and is recognized as an interventricular conduction abnormality on the ECG, commonly in the form of left bundle branch block. This contributes to abnormal ventricular contraction pattern, which further reduces cardiac output and exacerbates symptoms. Data from clinical trials have demonstrated that by pacing the right and left ventricle simultaneously, as in cardiac resynchronization therapy, ventricular contraction improves with a resultant reduction in symptoms and an improvement in cardiac output and quality of life in the majority of patients. This article provides an overview of ventricular dyssynchrony and the effect cardiac resynchronization therapy has on ventricular function and on quality of life and symptoms.