The “High Take-Off” Left Main Coronary Artery in a Patient With Acute Type A Aortic Dissection
A 73-year-old woman with a history of hypertension was admitted to the emergency room for chest pain and dyspnea. A chest radiograph showed mediastinal widening and increased cardiothoracic ratio (Figure 1A). Electrocardiography showed normal sinus rhythm without any ST changes (Figure 1B). Preoperative echocardiography was unremarkable except for moderate pericardial effusion. Enhanced computed tomography (CT) revealed acute type A aortic dissection with moderate amount of pericardial effusion and ectopic high origin of the left main coronary artery (LMCA; Figure 1C).
Emergency surgery was performed under cardiopulmonary bypass with cardioplegic arrest. During surgery, we recognized that LMCA originated ≈28 mm above the aortic valve and coursed down extramurally (Figure 2). LMCA was mobilized cautiously and separated from the aortic wall. After strengthening the dissected root by partial wrapping outside the root (the non and left coronary sinuses) with a cylindrical Dacron graft, 3 commissures were resuspended to an outer graft to preserve the aortic valve function. LMCA was reimplanted to the noncoronary sinus using a 6-mm ringed Gore-Tex graft (WL Gore and Associates, Flagstaff, AZ) to avoid kinking and external compression (Figures 2 and 3). After reimplantation, the ascending aorta was replaced under hypothermic circulatory arrest.
Postoperative course was uneventful and she was discharged without any complications. A follow-up CT showed patent graft (Figure 3).
Although it is difficult to estimate the exact prevalence, published data suggest that high take-off of LMCA ostium is an extremely rare anomaly.1,2 Ectopic high origin of coronary arteries has been defined variably in the literature as having ostium originating more than 5 mm above the supravalvular ridge, or 5 to 10 mm above the sinotubular junction.2 In our case, LMCA was located 12 mm above the sinotubular junction and 28 mm above the aortic valve. We believe that there are no other reported cases in the literature of diagnosed acute type A aortic dissection combined with this anomaly.
If not recognized preoperatively, LMCA can result in serious complications during aortic surgery because of inadequate myocardial protection and iatrogenic injury.3 Fortunately, the preoperative detection of this anomaly enabled us to avoid an injury to the coronary artery during aortic cross-clamping and surgical dissection by knowing the spatial relationship and its course of LMCA.
With regard to surgical procedure, this anomaly is 1 of the obstacles to supracommissural replacement of the ascending aorta. An important aspect of this case was how to deal with the high take-off LMCA during supracommissural replacement of the ascending aorta. Some surgical options available for this situation include coronary artery bypass graft, direct reimplantation to the left coronary sinus, reimplantation using a graft, unroofing of the intramural segment, or limited ascending aorta replacement.
Surgical strategy of choice is quite controversial. Coronary artery bypass graft is technically feasible, but should be followed by proximal ligation, which may become a future problem because of long-term patency. Multiple bypasses would be needed because single bypass could lead to hypoperfusion resulting from wide blood supply territories of LMCA. The fact that coronary artery bypass graft requires additional harvesting and multiple anastomoses is a limitation. Direct reimplantation to the left coronary sinus is 1 of the most physiologically beneficial procedures, but is technically difficult and has a risk of kinking of LMCA because of an extralength and a risk of bleeding at the anastomosis site attributable to the weakened root. Unroofing is a considerable procedure but was presently quite difficult because our case had an extramural course. Even if the course were intramural, unroofing would have remained impossible because dissected aorta become thinner and weaker after unroofing.
We undertook a LMCA reimplantation to the noncoronary sinus using a ringed Gore-Tex graft to avoid kinking and external compression by re-expansion of the aortic root. Before reimplantation, we wrapped the outside of the noncoronary and left coronary sinus with a cylindrical Dacron graft to strengthen and reinforce the dissected aortic root. We believe that the advantage of our procedure is its simplicity and more normal physiological character than other procedures. Furthermore, some published reports demonstrated that high takeoff coronary artery may be dangerous and lead to sudden death because of the risk of limited coronary blood flow attributable to an acute angle of origin of the coronary ostium relative to the aortic wall.4 Our procedure may expect a good long-term result because it could be more physiological and resolve an acute angulation problem. The long-term follow-up should be needed to confirm our hypothesis.
In conclusion, we performed ascending aorta replacement and LMCA reimplantation to the reinforced noncoronary sinus for acute type A aortic dissection with high takeoff LMCA. In this situation, detailed preoperative CT check-up and careful dissection are essential to avoid iatrogenic injury.
- © 2014 American Heart Association, Inc.