P0392 - Functionally subvalvar origin of the left coronary artery in a patient with Noonan syndrome and bicuspid aortic valve

Introduction: Anomalous aortic origin of the coronary arteries is a rare finding but represents the second most common cause of sudden cardiac death in young people. Multiple anatomical variations exist and can result in myocardial ischemia. Both Noonan syndrome and bicuspid aortic valve have been associated with coronary abnormalities.

Case Description: A 14-year-old with Noonan syndrome, bicuspid aortic valve, and previously repaired coarctation of the aorta presented with progressively symptomatic aortic valve stenosis. Magnetic resonance imaging showed a functionally bicuspid aortic valve with left-right cusp fusion and limited systolic excursion. Cardiac catheterization revealed a peak systolic gradient across the left ventricular outflow tract of 57mmHg. Surgical aortic valve intervention was recommended.
At surgery, two coronary anomalies were discovered. The right coronary artery (RCA) originated from the left side of the aorta above the sinotubular junction, traversed a long intramural course, and exited the anterior right sinus. The left coronary artery (LCA) originated from the left aortic sinus, though its ostia was dilated and flanked by a proximal thin veil of pseudo-leaflet tissue, resulting in a functionally subvalvar location underneath the true left aortic cusp. Imaging demonstrated only systolic antegrade LCA blood flow. Aortic valve repair was accomplished with commissurotomy, nodule resection, and leaflet thinning; concomitant unroofing of the RCA was performed along with resection of the thin tissue near the LCA ostia. Transesophageal echocardiography showed an acceptable aortic valve result.
In the immediate postoperative period, concern increased regarding the potential long-term risk of coronary malperfusion secondary to the persistent subvalvar origin of the LCA. Revision of the LCA to a usual position was recommended. The patient returned to the operating room and underwent a Ross aortic root replacement with a pulmonary autograft including reimplantation of both coronary arteries into the usual sinuses. The remaining hospital course was uneventful. Review of preoperative imaging demonstrated the anomalous aortic origin of the RCA with a long intramural course (Figure 1) and the anomalous origin of the LCA just proximal to the left aortic valve closing edge (Figure 2).

Discussion: Anomalous aortic origin of a coronary artery from a subvalvar position is extremely rare with just a few descriptions involving the RCA and left circumflex coronary origins. A distally displaced left-right fused commissure allowed for the LCA to originate from a subvalvar location underneath the true left coronary cusp. The long-term clinical implications of a subvalvar coronary artery origin are unclear, but absent or decreased diastolic flow may be associated with myocardial malperfusion, ischemia, and sudden death. Establishment of usual coronary anatomy and physiology with antegrade flow in diastole is recommended.

Conclusion: This case highlights the importance of unique coronary artery anatomy on pathophysiology and management strategy.