What is the interventricular septum (IVS) motion in a patient with left bundle branch block (LBBB)?

In patients with left bundle branch block (LBBB), the interventricular septum (IVS) typically exhibits dyskinetic or paradoxical motion during systole. This occurs because LBBB leads to the asynchronous contraction of the ventricles. The left ventricle depolarizes later than the right due to the blockage, causing an abnormal sequence of contraction.

As a result, while the right ventricle contracts normally, the left ventricle lags in its contraction, leading to a scenario where the IVS moves outward instead of the expected inward motion during systole. This paradoxical motion is a direct consequence of the altered electrical conduction and subsequent mechanical contraction of the heart muscle.

This distinct movement can be observed using echocardiographic imaging, helping clinicians identify the effects of LBBB on cardiac function. Understanding the dynamics of IVS motion in this context is crucial for diagnosing and managing patients who present with bundle branch block and associated cardiovascular conditions.