Abstract
Background
Surgical repair of transposition of the great arteries (TGA) is most commonly via the arterial switch operation (ASO). This involves translocation of the aorta and pulmonary trunk, typically with anastomosis of the branch pulmonary arteries anteriorly (LeCompte manoeuvre) and re-implantation of the coronary arteries onto the posterior neo-aorta. As such, the position of the coronary ostia may differ from their expected locations.
Purpose
To use ECG-gated CT angiography to describe the anatomic position of coronary ostia in post-switch TGA patients guiding potential catheter interventions in this population.
Methods
All post ASO patients who underwent CT imaging between 2008–2018 were identified. Patients with complex anatomy such as double outlet right ventricle were excluded. The positions of the coronary ostia were measured in degrees from vertical on a double-oblique reconstruction in the aortic valve plane. Ostium positions were compared to those of patients with no congenital heart disease via Watson's two-sample test of homogeneity for circular data. Angular dispersion was compared between groups via the Wallraff test. P<0.05 indicated statistical significance.
Results
Of 206 adult patients with TGA and ASO followed in our adult congenital heart disease centre, 38 (18.4%) had CT imaging available for analysis during the study period (mean age 24±6.8, 75% male).
The control group consisted of 15 patients investigated for chest pain (mean age 54±15.1, 73% male). In the control group, the right and left coronary ostia arose at a mean angle of −19 and +125 degrees from vertical (figure 1a). This was significantly different to the mean ASO coronary ostia clustered at mean angles of −70 and +29 degrees from vertical (Watson p<0.001) (figure 1b, with stenosis at the left coronary anastomosis).
There was no significant difference in spread of left ostia (Rho 0.9 vs 0.99, p=0.12), but right ostia were significantly more variable in ASO patients than controls (0.71 vs 0.96, p=0.003).
Figure 1
Conclusions
Coronary ostial positions in the neo-aorta of post-ASO patients differ significantly from those of normal controls, with considerable variability, especially in right coronary position. CT can demonstrate coronary ostia in 3D space and derive appropriate tube angles to guide catheterisation in post-operative congenital cardiac patients, optimise catheter selection, reduce catheterisation tome, radiation and contrast dose.
State-of-the-Art CT Imaging Techniques for Congenital Heart Disease