Alternating bundle branch block (ABBB) is a less commonly encountered phenomenon with the advent of re-perfusion therapy for acute myocardial infarction. ECGs simulating the appearance of an ABBB need to be carefully analysed. We present an ECG showing a baseline Left Bundle Branch Block(LBBB) progressing to a high grade AV block with escape complexes having a Right Bundle Branch Block (RBBB) m...

Gaps" in bundle-branch conduction were observed in three patients using the combined technic of premature atrial stimulation and His bundle recordings. In type I gap a complete LBBB pattern disappeared at shorter coupling intervals because the premature atrial impulses encountered enough delay at the A-V node to reach the left bundle branch after the end of its effective refractory period. When...

The authors thank Dr. N.H.G. Holford, assistant professor of Medicine, Pharmacy and Pharmacological Chemistry, University of California, San Francisco, for his constructive review of this manuscript, and Dr. S. Lee, Director, Hematology Department, Cedars-Sinai Medical Center. In addition, we express our gratitude to Joye Nunn for secretarial assistance, to Lance Laforteza for graphics, and to ...

Bundle branch block is a common cause of a widened QRS complex, and, as indicated in Table 1, different mechanisms may be responsible. Three are rate related and one is based upon retrograde invasion into the bundle branch. Those four mechanisms lead to the intermittent appearance of a bundle branch block pattern. Most commonly, bundle branch block is continuously present, so-called fixed bundl...

The three major coronary arteries of 10 normal human hearts were injected with differentially colored gelatin mass for histologic determination of the blood supply to the His bundle and proximal bundle branches. The His bundle was dually supplied by the A-V node artery and the first septal branch of the left anterior descending artery in nine hearts, but entirely by the A-V node artery in one. ...