1Echo Laboratory, Ootsubokai Towa Hospital, 2Department of Clinical Laboratory, The University of Tokyo Hospital, 3Department of Computational Diagnostic Radiology and Preventive Medicine, The University of Tokyo Hospital, 4Department of Cardiovascular Surgery, The University of Tokyo Hospital
left ventricular flow, right ventricular apical pacing, intraventricular dyssynchrony, strain rate imaging, tissue Doppler imaging
Timing of regional LV myocardial excitation and contraction could be altered by the location of the RV pacing lead. To our knowledge, late-systolic LV abnormal flow caused by RV pacing has never been reported. We report two cases with late-systolic LV abnormal flow from the mid-LV toward the apex during RV apical pacing. The abnormal flow disappeared with cessation of pacing and reappeared with resumption of pacing. Tissue Doppler imaging (TDI) and strain rate imaging (SRI) revealed that both contraction and relaxation occurred earlier in the apex than those in the basal LV during RV pacing. These findings suggested that the apex started relaxation in late systole while mid-to-basal LV was still contracting, which caused the abnormal pressure gradient leading to the abnormal intra-LV flow towards the apex in late-systole during RV apical pacing.