Unroofing of Left Main Coronary Artery with Trans-septal Course
Trans-septal/Intraconal Left
Main Coronary Artery (LMCA) is a rare form of coronary arterial anomalies. It
has been linked to increase risk of myocardial ischemia and sudden death. In
this anomaly, the proximal portion of LMCA is surrounded by the myocardium of
the interventricular septum. Usually there is a single anterior coronary artery
that gives origin to both right and left coronaries. Repair of such anomaly has
been challenging.
We present a 12-year-old boy who presented to the emergency room with
exertional chest pain. Initial evaluation with electrocardiogram,
echocardiography and stress test did not show evidence of ischemia and
otherwise structurally normal heart. Computed tomography scan shows single
anterior coronary artery that divides into both right and left branches. The
left main then dips towards the interventricular septum and travels for a
distance below the level of the pulmonary valve prior to exiting to the
epicardial surface and bifurcating.
The procedure was performed through a median sternotomy and mild hypothermic
cardiopulmonary bypass. After cardioplegic arrest, the main pulmonary artery
was transected proximal to its bifurcation and retracted caudally. A limited
aortotomy was performed and a probe is placed through the left main artery. The
pulmonary root in these cases require extensive mobilization similar to the
Ross procedure. Using a combination of Potts scissors and electrocautery at low
settings, unroofing is performed guided by the coronary probe. The second part
of the procedure require anterior translocation of the right main branch
pulmonary artery to maintain the inter-arterial space and avoid recurrence of
the compression by the pulmonary root.
The postoperative course was uneventful and the patient was discharged on the
fourth postoperative day.
In conclusion, trans-septal (intraconal) LMCA is a rare anomaly, that is linked
to myocardial ischemia and sudden death. It is important to understand the
3-dimensional location of the anomalous LMCA to facilitate the unroofing
procedure. Coronary artery bypass grafting is not advised in these cases and is
committed to fail. The two main principles of the procedure include (1)
Unroofing, and (2) anterior Translocation of the right main branch pulmonary artery.
References
1. Said SM, Cetta F. Pulmonary Root Mobilization and
Modified Lecompte Maneuver for Transseptal Course of the Left Main Coronary
Artery. World J Pediatr Congenit Heart Surg. 2020 Nov;11(6):792-796
2. Mainwaring RD, Hanley FL. Surgical treatment of anomalous left main coronary
artery with an intraconal course. Congenit Heart Dis. 2019 Jul;14(4):504-510
