Houston BA, et al. - Researchers assessed the acute biventricular hemodynamic response of cardiac resynchronization therapy (CRT) and other pacing configurations, including the effects of AV delay and atrial pacing, in patients with right bundle branch block (RBBB) and with LBBB, in order to determine the impacts of CRT in RBBB patients. They found a complex link between pacing configuration, AV delay and hemodynamic responses. Optimization of pacing modalities and AV delays might improve biventricular hemodynamic response among HF patients with RBBB. They also noted that in patients with diseases in which RV failure predominates, such as pulmonary hypertension and after left ventricular assist device, this may be particularly important.