Masquerading and Left BBB: BBBB

Report:

Atrial fibrillation with rapid ventricular response 150/min

Right bundle branch block

Left anterior hemiblock

Left bundle branch block

Bilateral bundle branch block.

Nonspecific ST/T changes

Comment:

In this case one can diagnose BBBB directly from the original trace.

In the limb leads there is hardly any difference between RBBB/LAHB complexes and those with LBBB (as seen from the rhythm strip on V1 below). This is the standard masquerading bundle branch block: RBBB and a very high grade of LAHB. Maybe it would also be a precordial masquerade with V7 and V8 taken, since the two blocks look remarkably similar in V6.

In this patient RBBB conduction predominated at faster rates and LBBB at slower rates, including sinus rhythm. Below (Fig 41a) is another fast trace with the rarely seen alternating BBB at the end.

Fig 41a.

Fig 42. 54 year old man with chronic renal failure.

If you have any suggestions for or feedback on this report, please let us know.