Left ventricular and biventricular pacing in congestive heart failure

Dual-chamber pacing improved hemodynamics acutely in a subset of patients w ith left ventricular (LV) dysfunction but conveyed no long-term symptomatic benefit in most. More recently, LV pacing and biventricular (multisite) pa cing have been used to improve systolic contractility by altering the elect rical and mechanical ventricular activation sequence in patients with sever e congestive heart failure (CHF) and intraventricular conduction delay or l eft bundle branch block (LBBB). Intraventricular conduction delay and LBBB cause dyssynchronous right ventricular and LV contraction and worsen LV dys function in cardiomyopathies. Both LV and biventricular cardiac pacing are thought to improve cardiac function in this situation by effecting a more c oordinated and efficient ventricular contraction. Short-term hemodynamic st udies have shown improvement in LV systolic function, which seems more pron ounced with monoventricular LV pacing than with biventricular pacing. Recen t clinical studies in limited numbers of patients suggest long-term clinica l benefit of biventricular pacing in patients with severe CHF symptoms. Con tinuing and future studies will demonstrate whether and in which patients L V and biventricular pacing are permanently effective and equivalent and whi ch pacing site within the LV produces the most beneficial hemodynamic resul ts.