Divided right ventricle: a review of its anatomical varieties.

Abstract

The first examples of muscular division of the morphologically right ventricle were described by Peacock [15] more than 100 years ago. Keith [13] subsequently described cases with a muscular shelf extending into the apical part of the ventricle. More recently, Brock [5] described cases of Fallot's tetralogy with a muscular diaphragm across the base of the pulmonary infundibulum. Tsifutis et al. [18] and Lucas et al. [14] subsequently reported cases of two-chambered right ventricle due to an anomalous muscle bundle, which they considered was produced by displacement of the origin of the moderator band from the septum. They reported this to be a newly recognized entity. Since then, a plethora of cases has been reported [3, 4, 7, 8, 10-12, 16, 17, 20, 21] without providing much further information. We have the impression that the terms "anomalous muscle band" and "double-chambered right ventricle" are now used interchangeably. Some of us have described other varieties of right ventricular division [4, 23] (Zuberbuhler et al., in preparation). It is evident that the so-called anomalous muscle band is only one of several lesions that can produce division of the ventricle. Our observations suggest that an anomalous muscle band is not necessarily associated with a double-chambered ventricle. We would like to reemphasize the concept of an intrinsic "tripartite" composition of the ventricular chambers [1] as a basis for a simple and satisfactory assessment of the types of right ventricular division.