What is in a Name? Methods and Discipline in the Subject of Coronary Artery Anomalies

The accompanying paper by Alhasan et al describes an unusual coronary pattern in a 56-year-old patient. Coronary artery angiograms revealed what was referred to as: “congenital absence of coronary ostium”, “congenital absence of a single ostium”, “absent right coronary artery”, or “single coronary artery”. Here we will briefly suggest some general principles and a discipline in an unusual field of cardiology: normality and abnormality in coronary artery anatomy and function.

1. The name and nature of coronary arteries refers to the dependent territory they feed, rather than their origin.¹

Indeed, a normal heart has three basic territories: the right atrioventricular (AV) groove and free wall of the right ventricle [the right coronary artery (RCA) territory], the left AV groove and obtuse margin of the heart [circumflex (CX) territory] and the anterior AV groove and anterior interventricular septum [left anterior descending coronary artery (LAD) territory]. Normally (in more than 99% of human cases), the CX and the LAD originate jointly from the same “common trunk” (the left main). It is unusual (an anomaly present in less than 1% of cases) not to have a single left main trunk, but such entity is compatible with normal coronary function (to feed the CX and LAD territories).¹

2. Coronary function depends on coronary stenosis. 

Coronary function is related not to coronary pattern, by itself, but to coronary lumen and blood flow.² Several coronary anomalies have been observed (some 80 of them!), and most are not cause of any functional impairment, clinical event, or mortality risk. However, a few congenital anomalies occasionally or systematically can cause myocardial ischemia manifestations, and lethal events.³ Anomalous origin of the coronary arteries should be classified essentially by the course of the anomalous proximal course. There are five different ways nature has solved the problem of anomalous origin coronary artery: 

1. Pre-pulmonic (in front of the pulmonary artery); 
2. Intraseptal (inside the ventricular septum); 
3. Intramural or pre-aortic (in front of the aortic root); 
4. Retro-aortic (behind the aortic root, it the space between aorta and the atria); 
5. Retro-cardiac (located in the posterior AV groove, at the crux of the heart).¹ 

The fundamental defect associated in the human adult with ischemia is the entity now called ACAOS, or anomalous coronary artery origin from the opposite sinus of Valsalva, with intramural course (inside the aortic media!).^3,4 This abnormal course of the ectopic artery (meaning: born at a unusual site) was initially called “between aorta and pulmonary artery”, but intravascular ultrasound imaging (IVUS) has clearly shown that the real location of this initial segment of the artery is inside the wall of the aortic root.^3,4 That intramural course causes lateral compression of the proximal ectopic coronary artery (RCA or LCA) and possible ischemia. The severity of such narrowing is variable in each patient and only the precision afforded by IVUS can establish it, at present.^3,4

The case of coronary anomaly presented by Alhasan et al in this issue of Cath Lab Digest is essentially a case of “anomalous origin of the right coronary artery from the left, with a retro-cardiac course”. This entity is rare and is a case of ectopic origin of the RCA, without any functional consequence: no ischemia is produced by such course (only the length of the RCA blood flow trajectory is a little longer than usual, when it runs at the right AV groove).² Unfortunately, the patient had the bad luck and risk factors of developing coronary arteriosclerotic disease at a site that normally would affect only the CX territory, but in his case, it was affecting also the RCA: a similar pattern to a left main trunk stenosis! Such a circumstance made dyspnea (and not typical angina) the initial manifestation when anatomic stenosis was not so critical (70% cross-sectional area stenosis by IVUS corresponds to some 50% diameter stenosis by angiography).

The Center for Coronary Artery Anomalies is a unique center that is part of the Texas Heart Institute in Houston, Texas. This non-profit entity is dedicated to the clinical study of coronary arteries anomalies, and to the prevention of sudden death in the athletes and the young, in general.

References

1. Angelini P, Villason S, Chan AV, Diez JG. Normal and anomalous coronary arteries in humans. In: Angelini P, ed. Coronary Artery Anomalies: A Comprehensive Approach. Philadelphia: Lippincott Williams & Wilkins; 1999:27–150. Available on the net, at: <texasheart.org.centerforcoronaryarteryanomalies>
2. Angelini P: Coronary artery anomalies: an entity in search of an identity. Circulation. 2007;115(10):1296-305
3. Angelini P, Walmsley RP, Libreros A, Ott DA: Symptomatic anomalous origination of the left coronary artery from the opposite sinus of Valsalva. Clinical presentations, diagnosis, and surgical repair. Tex Heart Inst J. 2006;33(2):171-9
4. 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