British Heart Journal, I973, 35, 796-798. Length of left main coronary artery

The length of the left main coronary artery has been measured in IOO coronary cineangiograms and in IOO postmortem hearts. The results indicate that an early bifurcation of the left main coronary artery is very much more common than previously suspected. The risks of aortic valve operation in cases with an early bifurcation are discussed. One of the advances in aortic valve surgery has been perfusion of the coronary arteries by direct cannula-tion during valve replacement. It has been suggested (Furlong et al., 1972) that a short left main coronary artery or a wide angle between its two main branches may result in underperfusion of the left circumflex artery or less commonly the left anterior descending artery. In such cases with an early bifurcation of the left main coronary artery the coronary cannula may selectively perfuse one main branch and to a greater or lesser degree occlude the other. Thus, a portion of myocardium remains underperfused throughout the bypass and infarction may result. The incidence of short left main coronary artery was therefore determined (a) in ioo coronary cine-angiograms and (b) in ioo postmortem specimens with normal hearts. Methods The ioo coronary cineangiograms were carried out in the cardiac department at St. Thomas ' Hospital, using Judkins or Sones techniques. The orifice of the main coronary artery could usually be visualized by spill-back of contrast medium during selective injection. The dis-tance between this point and the bifurcation of the left main coronary artery was measured in a single frame of the left selective coronary cineangiogram in the right anterior oblique position. Errors of magnification were corrected by photographing a perforated metal ruler (i cm perforations) at midchest level and adjusting the coronary artery measurement to this standard. In 6 cases, measurement of the left main coronary artery was technically impossible either because the vessel overlay some radio-opaque structure in this projection, or else because of very severe aortic regurgitation whic