Contribution to the V-V interval optimization in patients with cardiac resynchronization therapy

The present study proposed procedure for predicting an optimalleft and right ventricular pacing interval delay (V-V interval). In16 patients (heart failure, left bundle branch block, biventricularpacing) two methods (A and B) identifying optimal V-V intervalwere tested. Method A: predicted optimal V-V interval A (POVVA) = electromechanical delay of the segment paced by leftventricle lead minus electromechanical delay of the segmentpaced by right ventricle lead. Method B: predicted optimal V-Vinterval B (POVV-B) = difference in the onset of aortic andpulmonary flows. Both methods were validated usingechocardiography and right-sided heart catheterization. Cardiacoutput during POVV-A (4.6 l.min-1) was significantly better thanthat during POVV-A minus 20 ms (4.3 l.min-1, p<0.01) and POVVA plus 20 ms (4.3 l.min-1, p<0.01), and than that during POVV-B(4.4 l.min-1, p<0.05). LV dP/dt during POVV-A (818 mm Hg.s-1)exceeded that during POVV-A plus 20 ms (717 mm Hg.s-1,p<0.05) and POVV-A minus 20 ms (681 mm Hg.s-1, p<0.05), andthat during POVV-B (727 mm Hg.s-1, p<0.01). The timedifference in onsets of myocardial deformation of left ventriclesegment paced by the left ventricle and right ventricle leadallows identifying the optimal V-V interval and improves leftventricle performance.