**6.2.3 Angiographic diagnosis of preaortic course**

The LCA courses initially between the aorta and subpulmonary infundibulum, and behind the pulmonary trunk at left coronary sinus level. Then, the LMCA follows a normal course to its bifurcation. Therefore, all segments of the LAD coronary artery are visualized, and the

Proximal Anomalous Connections of Coronary Arteries in Adults 205

type A preinfundibular anterior and upward yes no short no type B retroinfundibular anterior and downward yes no short yes

and D preaortic posterior and upward no yes normal no type E retroaortic posterior and downward no yes normal no Table 7. Main angiographic characteristics of ectopic courses of anomalous connections of the left coronary artery with the opposite sinus or contralateral artery. LAD: left anterior

IVUS is an intracoronary imaging technique which provides qualitative and quantifiable features of the coronary anatomy in ANOCOR. Its high spatial resolution about 0.15 mm achieves a good anatomic visualization of the coronary artery wall. Other imaging modalities are not too competitive to analyse the shape and area of the ectopic orifice, and to identify an intramural segment. In this field, the contribution of the group of Angelini has been essential with a routinely use of IVUS in ANOCOR with a suspected intramural course (Angelini et al., 2003, Angelini et al., 2006, Angelini, 2007, Angelini & Flamm, 2007). In ANOCOR with intramural segment, IVUS imaging often visualizes the aortic wall at the level of the ectopic orifice. Several features, similar to histological and anatomical characteristics of ANOCOR with an intramural course, are well depicted by IVUS. Pharmacologic provocative tests may be associated during IVUS procedure. IVUS use is mentioned in ACC/AHA 2008 guidelines for adults with congenital heart disease, with a recommendation of class IIa and a level of evidence C, in order to delineate potential mechanisms of flow restriction (Warnes et al., 2008). Angelini et al. have defined several consistent IVUS characteristics regarding to ANOCOR with intramural segment

The orifice is never circular with an ovoid or ellipsoidal shape. The area of the slit-like ostium is not necessary significantly reduced, like during selective coronary angiography. It is the fact that the longest diameter of the orifice may be as long as the diameter of the distal segment. Importantly, the IVUS shows a normal intima tunica without

An IVUS hypoplasia of the intramural segment is demonstrated with a ratio <1.0 between the intramural minimal circumference and the distal reference circumference. The length of the intramural segment, generally ranged from 5 to 15 mm, may vary depending of the site of the ectopic orifice. The narrowing diameters and surfaces must be compared with the distal reference parameters. The baseline area of stenosis is the ratio between the distal area (mm2) minus the intramural area (mm2), and the distal area (mm2). The degree of area

**sign**

**dot sign**

**LAD length** 

**septal branches** 

 **ectopic course initial loop eye** 

types C

descending coronary artery.

(Angelini & Flamm, 2007).

**7.1 Abnormal orifice** 

atherosclerotic plaque.

**7.2 Intramural hypoplasia** 

obstruction varies between 30 and 70%.

**7. Intravascular ultrasonography (IVUS)** 

orientation of the CX coronary artery is normal. The initial course of the LMCA is upward and slightly posterior in RAO and LAO projections (figure 16). During 30° RAO ventriculography, the distal LMCA appears as a radiopaque "dot", anterior to the aorta.

Fig. 16. Angiographic view (right anterior oblique projection) showing a preaortic course of a left main coronary artery (white arrow) arising from the right sinus with a posterior and upward loop (star).
