The anatomical arrangement of the myocardial cells making up the ventricular mass

Abstract

The architectural arrangement of the myocytes within the ventricular mass remains a highly contentious topic. It has recently been suggested by several distinguished surgeons that the overall myocardial structure is disposed in the form of a 'ventricular myocardial band'. There are, however, major anatomic deficiencies in this hypothesis, because the heart is formed on the basis of a modified blood vessel, rather than a collection of discrete muscular entities resembling the skeletal musculature. There is ample alternative evidence, nonetheless, already existing to provide a suitable explanation for the 'forceful reciprocal twisting' of the ventricular mass that is seen by cardiac surgeons during operative procedures. We provide here, therefore, a review of the anatomical studies we have performed separately and conjointly over a period of nearly 30 years. As before, we show that there is no anatomic evidence to support the concept of the 'ventricular myocardial band'. The overall arrangement is for the myocytes to be supported as the muscular components of a continuous and complex mass, the supporting collagenous fibrous matrix possessing epimysial, perimysial, and endomysial components. It had already been discussed at length during the previous century why there was no anatomic evidence to support the existence of separate 'muscles' within the ventricular continuum. There are no fibrous sheaths within the ventricular walls that permit the myofibres to be dissected on the basis of muscle bundles having a discrete origin and insertion, as is the case with the arrangement of the skeletal muscles. We have never sought ourselves, however, to deny the central helical nature of the overall architecture of the ventricular walls. The anatomic evidence supporting an overall helical nature for the ventricular myocardium has existed for over 150 years. All the available evidence, nonetheless, shows that these helical patterns are to be found throughout the walls, and in no way constitute a unique myocardial band.