Image of the Month - March 2016 - single coronary artery arising from the right coronary cusp

Submitted by Dr I. Nagra, Consultant Radiologist, Worcestershire Acute Hospital.

Coronary artery anomalies (CAAs) are present in 1-1.96% of the population (1,2).  The significance of single CAA’s differs depending on the course of the artery.  Those that take an inter-arterial route between the aorta and pulmonary artery are considered malignant, often presenting with syncope or sudden death (1,3). This is attributed to myocardial ischaemia from compression of the single coronary artery (SCA) between two high-flow structures in systole. Conversely, those that traverse benign, inter-ventricular paths do not predispose to myocardial ischaemia and hence are often asymptomatic (1,3).

The CT coronary angiography and volume rendered images shows a SCA arising from the right coronary cusp in a 68 year-old male who presented with atypical chest pain. The images show both the right coronary artery (RCA) and left main stem (LMS) arising from the right coronary cusp. A long benign, inter-ventricular course of the LMS is undertaken before bifurcation into the LAD and LCx, both of which contain calcified eccentric plaques. Mixed plaque disease causing moderate to severe stenosis of the RCA was noted. This CAA is rare, with a prevalence of 0.004 - 0.05% (2). According to the Lipton classification system, this represents an R-II S single coronary artery anomaly (4).

Given the benign course of the SCA, the atypical chest pain is likely to be secondary to the significant plaque disease rather than the CAA. Some authors suggest that atherosclerosis is accelerated in those with a SAA (5). Knowledge of anomalous coronary artery anatomy is of considerable benefit especially if invasive treatment for coronary artery disease is required. 

March 2016 IOTM

 

References

  1. Laspas F, Roussakis A, Mourmouris C, Kritikos N, Efthimiadou R, Andreou J. Coronary artery anomalies in adults: imaging at dual source CT coronary angiography. J Med Imaging Radiat Oncol. 2013 Apr;57(2):184-90.
  1. Erol C, Seker M. Coronary artery anomalies: the prevalence of origination, course, and termination anomalies of coronary arteries detected by 64-detector computed tomography coronary angiography. J Comput Assist Tomogr. 2011 Sep-Oct;35(5):618-24.
  1. Angelini P, Flamm SD. Newer concepts for imaging anomalous aortic origin of the coronary arteries in adults. Catheter Cardiovasc Interv. 2007 Jun 1;69(7):942-54.
  1. Lipton MJ, Barry WH, Obrez I, Silverman JF, Wexler L. Isolated single coronary artery: diagnosis, angiographic classification, and clinical significance. Radiology. 1979;130:39-47.
  1. Rigatelli G, Gemelli M, Zamboni A, Docali G, Rossi P, Rossi D, et al. Are coronary artery anomalies an accelerating factor for coronary atherosclerosis development? Angiology 2004;55:29-35.