EFFICACY OF THE LEFT ANTERIOR OBLIQUE (LAO) VIEW OF THE LEFT CORONARY ARTERY WITH CRANIAL ANGULATION

Abstract

To assess the efficacy of cranial angulation of the X-ray beam in studying the left coronary artery (LCA) tree during coronary cineangiography (CCA), 975 CCAs were reviewed retrospectively. In 297 cases, the study included a cranially angulated left coronary arteriogram in the LAO projection (LAO-C). Results: In 121 of the 297 cases (41%), the LAO-C view significantly enhanced coronary artery imaging. Among these 121, this view provided 204 specific instances of additional diagnostic information, which in turn could be divided into 5 different types: (a) In 92 instances, the LAO-C projection provided the clearest view of a lesion so that its severity could be graded with confidence. (b) In 47 instances, the anatomy of the proximal LCA tree was clarified so that it became more apparent in which branch a lesion was located. (c) In 29 instances, the LAO-C projection revealed that a lesion was significantly more severe than had been suspected on the standard views. (d) In 18 instances, the LAO-C projection allowed exclusion of a lesion which had been initially suspected on the standard views. (e) In the final 18 instances, the LAO-C projection was the only view to demonstrate a lesion. Among these 204 instances, the affected vessels were the left anterior descending artery (LAD) in 84 cases, a ramus medianus or diagonal branch of the LAD in 90 cases, the proximal circumflex artery or one of its obtuse marginal branches in 23 cases, and the main LCA in 7 cases. Conclusions: (1) The LAO-C projection should be routinely obtained on all CCAs. (2) If the LAO-C projection of the LCA can be quickly and simply obtained (depending upon the equipment available), it should be the first view obtained and can in most cases replace the standard LAO projection. (3) If only a single view of the LCA can be obtained (e.g. in a critically ill patient with unstable angina or suspected main LCA stenoses), it should be the LAO-C view. (4) A major explanation for the finding in earlier studies that CCA underestimates the severity of coronary disease is that many lesions were suboptimally demonstrated before the introduction of angulated views.