**5.3.2 Retroinfundibular course (type B)**

A clear understanding of the retroinfundibular course remains difficult. Due to a low risk of lethal cardiac events, examinations of heart specimens with a retroinfundibular course are rare. However, tomographic imaging allowed a better analysis of their relationships with the adjacent structures (figure 10). The retroinfundibular course, without exception, involves the LCA and their branches. The ectopic vessel first courses behind the subpulmonary infundibulum, then crosses between the latter and the ventricular septum, and finally emerges from the interventricular space to join the left ventricle on the epicardial surface at the mid LAD level. In the literature, the retroinfundibular course is also known as

**SPI SPI** 

**C** 

**LS** 

**LS** 

**SPI SPI** 

**D** 

Fig. 9. Anatomic representation of the courses of an anomalous left coronary artery arising from the right sinus. A: preinfundibular course, B: retroinfundibular course, C: preaortic

**RS RS** 

**RS RS** 

The prepulmonary course involves the ectopic paths coursing on the surface of the pulmonary trunk or subpulmonary infundibulum. The latter is mostly concerned. In case of a long and sinuous course, both pulmonary trunk and subpulmonary infundibulum may be in contact with the ectopic vessel. The vessel coursing with a prepulmonary path, almost without exception, is the left coronary artery (LMCA or LAD or septal branch arising from

A clear understanding of the retroinfundibular course remains difficult. Due to a low risk of lethal cardiac events, examinations of heart specimens with a retroinfundibular course are rare. However, tomographic imaging allowed a better analysis of their relationships with the adjacent structures (figure 10). The retroinfundibular course, without exception, involves the LCA and their branches. The ectopic vessel first courses behind the subpulmonary infundibulum, then crosses between the latter and the ventricular septum, and finally emerges from the interventricular space to join the left ventricle on the epicardial surface at the mid LAD level. In the literature, the retroinfundibular course is also known as

course, D: retroaortic course. LS: left sinus, RS: right sinus.

**LS** 

**A** 

**B** 

**LS** 

**5.3.1 Preinfundibular course (type A)** 

**5.3.2 Retroinfundibular course (type B)** 

the opposite sinus or the RCA).

subpulmonic or intraseptal or intraconal course. The nomenclature used in this review appears more appropriate regarding the cardiac anatomy. The left coronary artery (LMCA or LAD) with retroinfundibular course provide always one or more septal branches in the floor of the right ventricular outflow tract.

Fig. 10. Computed tomography imaging of an ectopic left main coronary artery (arrow) arising from the right sinus with a retroinfundibular course. AO: aorta, SPI: subpulmonary infundibulum.

#### **5.3.3 Preaortic course with intramural segment (type C)**

The typical preaortic course is tangential to the aorta through the fibroadipose tissue separating the arterial roots, (figure 11). Nomenclatures using the so-called interarterial course, in other words between the aorta and the pulmonary artery, may be ambiguous. In fact, a LCA connected in the opposite sinus or contralateral artery, and coursing anterior to the aorta, is in contact first with the subpulmonary infundibulum. A close contact with the pulmonary trunk is also possible because a LCA arising from the opposite sinus with a preaortic path, courses distally near the usual origin of the vessel before to join the interventricular groove. Conversely, an ectopic RCA is in contact first with the pulmonary trunk and then with the subpulmonary infundibulum before to join the atrioventricular groove. ANOCOR with high take-off from the aorta above the sinuses have, by definition, a preaortic course. The presence of an intramural segment, as defined above, must be systematically looked for in order to stratify the risk.

Proximal Anomalous Connections of Coronary Arteries in Adults 199

Fig. 12. Computed tomography imaging of anomalous connection of the left main coronary artery (arrow) with the right sinus close to the right coronary artery (arrowhead). LA : left

**LA**

As mentioned above, a single coronary artery is never associated with an abnormal proximal course. The myocardium usually dependant on the absent coronary artery is fed by a retrograde flow using a coronary network, near normal. Besides, a coronary artery, connected with the contralateral artery far from the proximal segment of the latter, may

Rare ANOCOR, such as abnormal origin from the aortic arch, may have another ectopic course, often complex, in contact with several structures. A LMCA with an anomalous connection with the pulmonary trunk courses usually facing the left side of the latter.

The diagnosis of ANOCOR in adult patients is usually suspected or achieved during a selective coronary angiography scheduled to evaluate or to rule out a CAD. The invasive coronary angiography is no longer considered the method of choice, in other terms *the gold standard*, for an accurate diagnosis of ANOCOR. Studies have described the correlations between invasive angiography and CT angiography but always in small populations. Correct identification of the ectopic vessel was achieved by conventional angiography in 69% (9/13) of ANOCOR (Shi et al., 2004). Selective catheterization and precise vessel determination was possible in only 53% (8/15) of ANOCOR (Schmitt et al., 2005). The coronary abnormality was accurately depicted in 44% (4/9) of ANOCOR (de Jonge et al., 2008). Several shortcomings of the conventional angiography are obvious, such as a difficult canulation of the abnormal orifice, a two-dimensional interpretation of the ectopic course, or

atrium.

**5.3.6 Absent proximal ectopic course (type F)** 

have normal relationships with the cardiac structures.

**6.1 Angiographic diagnosis of ectopic vessels** 

**6. Angiographic diagnosis of ectopic vessels and courses** 

**5.3.7 Other ectopic courses (type G)** 

Fig. 11. Volume-rendered computed tomography images of an ectopic right coronary artery (arrow) arising from the left sinus with a preaortic course tangential to the aorta.
