International Medical Case Reports Journal (Nov 2020)
Left Ventricular Contraction Sequence in a Case Where the QRS Changed from Left to Atypical Right Bundle Branch Block
Abstract
Hideyuki Hara,1 Takako Nagata,2 Hiroshi Ito,1 Shinichi Niwano,2 Junya Ako2 1Division of Cardiology, Numazu City Hospital, Numazu, Japan; 2Department of Cardiovascular Medicine, Kitasato University School of Medicine, Sagamihara, JapanCorrespondence: Hideyuki HaraDivision of Cardiology, Numazu City Hospital, Aza-Harunoki 550, Higashi-Shiiji, Numazu City, Shizuoka Prefecture 410-0302, JapanTel +81-55-924-5100Fax +81-55-924-5133Email [email protected]: A subgroup of right bundle branch block (RBBB) patients may exhibit a significant left ventricular (LV) activation delay. We evaluated echocardiography in a non-ischemic heart failure patient whose QRS morphology changed from left bundle branch block (LBBB) to atypical RBBB. The septum to posterior wall motion delay (SPWMD) measured using the M-mode was 196 ms while the patient presented with LBBB but decreased to 32 ms after the morphology changed to RBBB. These changes were also associated with delayed appearance of the septal displacement peak. Speckle tracking longitudinal strain was evaluated using three standard apical views after the morphology changed to RBBB. The LV contraction initially appeared in the basal inferior wall and there was delayed anterior wall contraction. The LV contraction pattern in our patient changed when the QRS morphology changed to atypical RBBB. A specific LV contraction sequence observed in atypical RBBB may reflect a significant LV activation delay between the inferior and anterior wall.Keywords: left bundle branch block, right bundle branch block, masquerading bundle branch block, bilateral bundle branch block, activation delay, longitudinal strain
