This week we are pleased to introduce our guest writer, Dr. Sukhvinder Singh. He will discuss the role of echocardiography in the presence of Left Bundle Branch Block Dr. Singh is a board certified cardiologist in India with 10 years of experience. He has worked at St. Stephen Hospital and Delhi Heart and Lung Institute and sits on the editorial board of many journals including International Journal of Diagnostic Imaging and Indian Journal of Cardiobiology and Clinical Sciences. He is Review Board Member for cardiology and cardiovascular sciences for many international journals including BMJ group. He has a book chapter and more than 15 papers in various national and international journals to his credit. His key areas of interest are Tele-cardiology, preventive cardiology, echocardiography, stress testing and non-interventional cardiology. Dr. Singh currently runs a tele-cardiology web portal www.telecardiologyindia.com.
Regional wall motion abnormalities are a common abnormality encountered by cardiac sonographers and interpreters. Regional wall motion abnormalities are often easier to recognize in clinical circumstances suggestive of coronary artery disease (CAD) versus non-coronary scenarios. Some reasons for non-coronary wall motion abnormalities being difficult to distinguish are because they are uncommon and less discussed, thus decreasing our experience with them. One such abnormality is Left Bundle Branch Block (LBBB). LBBB produces a wall motion abnormality that may mimic ischemic wall motion abnormality of the interventricular septum. Therefore, it is important for careful evaluation of wall motion in the presence of LBBB.
What is LBBB?
LBBB is a common conduction disorder that may be present with or without any structural heart disease. LBBB is identified on ECG by the following criteria.
LBBB produces a wall motion abnormality that may mimic ischemic wall motion abnormality of interventricular septum. With careful evaluation of wall motion in the presence of LBBB, we can identify signs that help us to better differentiate ischemic wall motion abnormalities from LBBB.
The normal motion of interventricular septum (IVS):
In all cases of LBBB it is important to record M-Mode through the anterior septum and the Mitral valve in Parasternal Long Axis (PLAX) with ECG gating. There is a beak like projection of IVS in M-mode in early systole
Below Figure 1 – Red Arrow
Below Figure 2 – Purple Arrow
Besides these characteristic finding, there may be inter-segmental temporal dys-synchrony in the left ventricle that may not always be apparent to eyes in every case. What is temporal dyssynchrony? This simply means that some of the LV segments contract later than other segments of the LV. In a normal LV, all segments tend to contract simultaneously. With LBBB there is an increase of total time taken to activate the left ventricle (increased QRS duration) and the inferolateral and anterolateral segments contract later than the other segments.
Let’s review some video images and pay specific attention to the motion of the anterolateral and inferolateral wall segments.
Parasternal Short Axis of the LV
Apical 4 Chamber
Apical 4 Chamber
In patients presenting with symptoms suggestive of CAD, echocardiographic conclusion that wall motion is explained by LBBB only is not sufficient to close the case. However, in those cases where patients are asymptomatic or have symptoms of some other disease (Non-CAD), a conclusion that the wall motion abnormality is due to LBBB only, helps clinicians to make the correct interpretation.
1. Early systolic beaking of IVS followed by transient or prolonged paradoxical motion
2. Preserved wall thickening of IVS
3. The wall motion abnormality will be restricted to basal and mid segments and will not extend to apical segments.
4. Intersegmental temporal dys-synchrony
5. No area of wall thinning
Dr. Singh currently runs a telecardiology web portal www.telecardiologyindia.com
1. Dillon JC, Chang S, Feingenbaum H. Echocardiographic manifestations of Left bundle branch block. Circulation (May 1974). Vol 49. 876-80.
By: Sukhvinder Singh, MD, DM (Cardiology). www.telecardiologyindia.com