The Annals of Thoracic Surgery, Vol 40, 599-613, Copyright © 1985 by The Society of Thoracic Surgeons
A histological study of surgical landmarks for the specialized atrioventricular conduction system, with particular reference to the papillary muscle
T Tamiya, T Yamashiro, T Matsumoto, S Ogoshi and H Seguchi
Surgical landmarks of the conduction system were histologically evaluated
in 29 cardiac specimens. The distribution of the system was grossly
inherent to the type of ventricular septal defect as classified by Soto and
coworkers, although it varied individually. The relationship of the right
bundle branch (RBB) to the papillary muscles was of surgical interest. In
defects unrelated to maldevelopment of the septum of the conus, the RBB
passed beneath or slightly anterior to upper accessory papillary muscles
(AcPMs) and posterior to the medial papillary muscle (MPM), regardless of
the subtype of defect. In defects caused by maldevelopment, such as
tetralogy of Fallot, it passed anterior to the MPM. Such data support the
hypothesis that the RBB descends beneath or anterior to embryological upper
AcPMs, whatever the morphological role may be, because of the supposedly
independent developmental origin of the MPM and AcPMs. The relationship
between the RBB and upper AcPMs appeared further modified by the attitude
of the trabecula septomarginalis. Our improved clinical results have
demonstrated that such information offers a gross but practical guide for
prevention of conduction disturbances.
