The anatomic variability of the coronary vasculature of the human heart--part I: functional vascular zones--a morphological view.

The myocardium may be divided into distinct zones which act as functional units of the coronary vascular network. The basic principle of this functional systematization of cardiac blood vessels is a constant relationship between the "distributing" and the "delivering" vessels. Six arterial zones of the myocardium are identified under this scheme: anterior right ventricular, lateral left ventricular, posterior left ventricular, interventricular septal, posterior right ventricular, and atrial. The distributing vessels of functional myocardial zones are most frequently both arterial and venous. However, between the lateral and posterior left ventricular zones there is sometimes only the left marginal vein (24%) or left marginal artery (20%). Between the atrial and posterior right ventricular zones there is sometimes only the right coronary artery (52%), or only the small cardiac vein (14%) as a distributing vessel. Between the left and the right posterior ventricular zones there is sometimes an arterial and sometimes a venous distributing vessel (10%). Between the posterior and anterior right ventricular zones there is either the artery (21%) or the right marginal vein (8%) as a distributing vessel. The permanence of the six functional myocardial zones is determined not only by the arterial but also by the venous distributing vessels, and in some cases the venous vessels are the only distributing vessels between certain zones.