Abnormal motion of Interventricular septum (IVS) in a patient with LBBB in Apical four chamber view

This echocardiography clip is showing an abnormal motion of Interventricular septum (IVS) in a patient with LBBB in Apical four chamber view (A4CH). In a majority of patients with left bundle-branch block (LBBB), there is abnormal leftward motion of the interventricular septum during the pre-ejection phase. This motion was considered to be passive, caused by early rise in right ventricular (RV) pressure.