An Illustrative Case of a Frequently-Held Misconception: The “Absent” RCA

• A “coronary artery” is one of the main arteries of the heart (different than coronary “branches”);
• The “right coronary artery” is the one that normally feeds the right ventricle (free wall) and, when dominant, the postero-basal septum;
• The nature of a coronary artery is defined by the dependent myocardial territory, and not by its origin — a normal heart has 3 coronary arteries: the left anterior descending (LAD), the circumflex (CX) and the RCA.
• What may vary is the dominance of a given artery and its origin.

Quite clearly, in Hussain’s patient,¹ there was:
a. A single coronary ostium (but not a single coronary artery!⁵);
b. A mixed, common proximal trunk off the left sinus of Valsalva, providing the LAD (first artery) and the CX - RCA artery (posterior branch off the common proximal trunk). The RCA was indeed not absent, but a prominent distal branch of the CX and its continuation behind the atrioventricular (AV) valves.⁵ The RCA had a normal, dominant, dependent territory with the posterior descending artery and the right ventricular and conal terminal branches. This is called the posterior (to the AV valves) course of an ectopically originating RCA from the left coronary artery.⁵ An “absent coronary artery” is generally a misnomer and likely a biologically impossibility, since myocardium of any sizeable thickness cannot develop in humans without its feeding coronary artery.
The use of the word “absent” implies ischemia2–4 and should generally be avoided without proper documentation. The patient described by Hussain and colleagues indeed had “apical” ischemia due to an acquired obstruction of the proximal LAD, and no ischemia of the pseudo-absent RCA territory.
Words are important, especially because they are the means to communicate concepts.

Paolo Angelini, MD
Texas Heart Institute
Houston, Texas
E-mail: pangelini@rr.houston.com

Author’s Response

We appreciate the comments of Dr. Angelini and value his suggestions. We respectfully disagree, however, with his assertion that an “absent” vessel implies ischemia, as he emphasized in his letter. We believe the distinction between naming the vessel that supplies the right ventricle in our patient as a branch of the left circumflex artery (LCX) and an aberrant right coronary artery (RCA) is overemphasized. However, as Dr. Angelini stated in his letter, “words are important as a means to communicate concepts”, we feel that the vessel should be labeled as a branch of the LCX, as it would be difficult to accurately delineate the transition point between the origin of the RCA and the termination of the LCX.

Sayed T. Hussain, MD
Division of Cardiovascular Diseases
University of Cincinnati
Cincinnati, Ohio
E-mail: hussaist@ucmail.uc.edu

References

1. Hussain ST, Khoury SF. An illustrative case of an absent right coronary artery. J Invasive Cardiol 2008;20:150.
   
2. Susmano A, Colandrea MA, Bogdonoff ML, Muenster JJ. Congenital absence of the circumflex coronary artery. Clinical and cinearteriographic observations. Am Heart J 1973;86:811–816.
   
3. Donaldson RM, Raphael MJ. Missing coronary artery. Review of technical problems in coronary arteriography resulting from anatomical variants. Br Heart J 1982;47:62–70.
   
4. Ilia R, Jafari J, Weinstein JM, Battler A. Absent left circumflex coronary artery. Cathet Cardiovasc Diagn 1994;32:349–350.
   
5. Angelini P. Normal and anomalous coronary arteries in humans. In: P. Angelini (ed): Coronary Arteries Anomalies. Philadelphia: Lippincott, Williams & Wilkins. 1999, pp. 27–79.