Mahaim and James fibers as a basis for a unique variety of ventricular preexcitation.


Journal Article

This report concerns pathologic findings in a 54 year old woman with intermittent preexcitation who died of carcinoma of the breast. Electrocardiograms revealed predominantly normal sinus rhythm with a normal P-R interval and narrow QRS complex. Episodes of sinus rhythm, short P-R interval and QRS widening (with delta wave) were also recorded. During preexcitation QS complexes were noted in leads II, III, aVF, V1 and V4 to V6. Delta waves were negative in leads II, III, aVF and V1 isoelectric in leads V4 to V6 and positive only in leads I, aVL, V2 and V3. This case thus defies classification into any known variety of preexcitation. Complete serial sections, cut through the entire conduction system and both atrioventricular (A-V) rims, totaled 18,600 sections. These revealed no bundle of Kent. Instead, Mahaim fibers histologically identified as His bundle tissue gave off from the A-V bundle to both the right and the left sides of the septum associated with the normal fibers of James. This case reveals that (1) fibers of James can bypass the A-V node, (2) fibers of Mahaim can conduct, and (3) there are types of preexcitation in addition to types A and B.

Full Text

Cited Authors

  • Lev, M; Fox, SM; Bharati, S; Greenfield, JC; Rosen, KM; Pick, A

Published Date

  • December 1, 1975

Published In

Volume / Issue

  • 36 / 7

Start / End Page

  • 880 - 888

PubMed ID

  • 1199944

Pubmed Central ID

  • 1199944

International Standard Serial Number (ISSN)

  • 0002-9149

Digital Object Identifier (DOI)

  • 10.1016/0002-9149(75)90077-6


  • eng

Conference Location

  • United States