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MMCTS
(May 23, 2008). doi:10.1510/mmcts.2008.003285 Copyright © 2008 European Association for Cardio-thoracic Surgery Procedure Anomalous origin of the left coronary artery from the pulmonary artery: surgical treatmentDepartment of Pediatric Cardiac Surgery, Sick Children Hospital, Paris, France * Corresponding author: Service de Chirurgie Cardiaque Pédiatrique, Hôpital Necker, Enfants Malades, 149 rue de Sèvres, 75015 Paris, France. Tel.: +33-1-4438 1867; fax: +33-1-4438 1911pascal.vouhe{at}nck.aphp.fr
Anomalous origin of the left coronary artery from the pulmonary artery is a rare malformation in which the left coronary artery originates from the pulmonary artery. The consequences are variable although, in most cases, this anomaly leads to severe coronary hypoperfusion and left ventricular dysfunction when pulmonary vascular resistances fall in the postnatal period. Surgical correction is indicated as soon as the diagnosis is established. In nearly all cases, the anomalous artery can be excised from its pulmonary origin, mobilized and reimplanted directly into the ascending aorta. In rare circumstances, technical modifications must be used to restore a normal dual coronary perfusion. The operative risk is related mainly to the severity of preoperative left ventricular dysfunction. The current mortality rate is low, but postoperative left ventricular assist device implantation may be necessary in the most severe cases. After successful revascularization, the late results are satisfactory; left ventricular function always recovers; mitral regurgitation, if present, decreases, although reoperation may be necessary for residual ischemic mitral insufficiency.
Key Words: Anomalous origin of left coronary artery from pulmonary artery • Congenital cardiac defect • Coronary anomaly • Surgical correction
Anomalous origin of the left coronary artery from the pulmonary artery is a rare malformation in which the left coronary artery originates from the pulmonary artery. Other, even more uncommon, anomalies include anomalous origin of the right coronary artery, left anterior descending or circumflex artery. Anomalous origin of both the left and right coronary arteries is extremely rare and nearly uniformly lethal. In the absence of surgical correction, the natural prognosis is poor with an 80–90% mortality rate by one year of age. Various surgical techniques have been used to create a dual coronary artery system. Direct aortic reimplantation of the anomalous artery has progressively evolved as the procedure of choice [1].
Surgical anatomy
Pathophysiology If the left coronary artery is dominant and if intercoronary collaterals are inadequate, severe left ventricular dysfunction with ischemic mitral regurgitation develops; the prognosis is poor in the absence of early surgical correction. On the contrary, if the right coronary artery is dominant and if intercoronary collaterals develop efficiently, near normal left coronary perfusion may be maintained while left-to-right shunt from the right coronary artery to the left coronary artery and the pulmonary artery progressively increases; the anomaly may then be discovered during childhood or adulthood in patients with relatively preserved ventricular function.
Diagnosis and indications When the child survives past infancy, the diagnosis may be suspected in a patient with moderate left ventricular dysfunction, mitral regurgitation or ischemic symptoms at exercise. Once the diagnosis is established, surgical correction is indicated to restore a normal dual coronary perfusion.
General principles In most patients, particularly in infants, preoperative left ventricular function is poor, often extremely poor. Everything should be done to minimize further ischemic damage. Normothermic cardiopulmonary bypass is usually used, although moderate hypothermia may be necessary to allow low flow bypass if needed. Myocardial preservation is achieved using multidose blood cardioplegia. As soon as bypass is started, a left ventricular vent is inserted through the superior right pulmonary vein and both pulmonary arteries are snared to avoid runoff of coronary perfusion into the pulmonary circulation. The first cardioplegic administration is performed in the aortic root (and thus right coronary artery) and it is completed by direct administration into the anomalous left coronary ostium as soon as the pulmonary trunk has been opened. Subsequent cardioplegic administrations are performed in both coronary ostia. It is very useful to leave (or to create) a calibrated small atrial septal defect as a way to unload the failing left ventricle during the early postoperative period. Immediately after aortic unclamping, a left atrial line is inserted and weaning from cardiopulmonary bypass is prepared. In some patients, weaning can be achieved with an acceptably low left atrial pressure and minimal inotropic support. In most cases however, cardiopulmonary bypass must be prolonged for a while until left atrial pressure (which is initially high) reaches an acceptably low level, allowing weaning with a moderate inotropic support. If this is not the case, a left heart assist device must be implanted to allow cardiac assistance for a few days until left ventricular function recovers enough to allow weaning in good hemodynamic conditions.
Usual technique of coronary artery reimplantation (Schematic 1)
Using a coronary probe, the main trunk and its division into left anterior descending and circumflex arteries are carefully identified. The main coronary trunk is mobilized down to its bifurcation. This step is performed using electrocautery, great care being taken to achieve perfect hemostasis of the numerous small veins which are usually surrounding the coronary arteries (Video 3).
The ascending aorta is opened vertically and the ideal site of reimplantation in the left posterior wall of the aorta is determined. A hole is created using a punch, care being taken not to injure the aortic valve (Video 4).
The coronary button is reimplanted using a running suture. Coronary reimplantation must be achieved without torsion or excessive tension of the coronary button. According to anatomic conditions, suturing may be performed either from inside the aorta or from outside the vessel. The ascending aorta is closed (Video 5).
Cardioplegic infusion is administrated into the aorta to insure that coronary perfusion is adequate and perfect hemostasis achieved. The ligamentum arteriosum is divided and the main pulmonary arteries are fully mobilized (Video 6).
A fresh piece of autologous pericardium is used to close the gap created in the pulmonary root. The pulmonary trunk is reconstructed, avoiding any risk of compression of the reimplanted left main coronary artery (Video 7).
Technical variants The previously described technique can be used in nearly all cases. There are, however, two rare circumstances in which technical modifications may be necessary. Anomalous origin from the anterior pulmonary sinus (Schematic 2).
The anomalous coronary ostium is harvested with a circular portion of the pulmonary artery wall. The segment of pulmonary artery is used to create a tubular neo-left main trunk thus allowing standard reimplantation into the aorta. A valvular commissure must occasionally be taken down and repaired subsequently. Alternatively, a flap of pulmonary wall may be used to create the posterior wall of the new left coronary trunk while the anterior wall is constructed using a patch of fresh autologous pericardium (Videos 8 and 9).
Anomalous origin from the right pulmonary artery with an intramural aortic course [3] (Schematic 3).
Very rarely, the anomalous coronary artery originates from the posterior wall of the right pulmonary artery and presents an initial intramural segment within the aortic wall. The ascending aorta and the pulmonary artery are opened and the anomalous ostium is identified. Using a coronary probe, the intramural segment is carefully located. The common wall between the aorta and the coronary artery is excised and the intimas of both vessels are approximated using a series of interrupted absorbable sutures, thus creating a neo-coronary ostium within the aortic lumen. The anomalous ostium in the pulmonary artery is then sutured or the artery ligated at its origin.
Between 1986 and 2007, 62 consecutive patients with anomalous left coronary artery arising from the pulmonary artery, underwent isolated aortic reimplantation. There were 23 boys and 39 girls. Mean age was 16 months (range 10 days to 11 years). There were six early deaths (9.7%). The causes of death were: arrhythmias in 2, neurologic complication in 1, multiorgan failure in 1 and intractable low cardiac output syndrome in 2 patients. A left heart assist device was implanted in 4 patients. All were weaned from assistance but two died after weaning (neurologic complication in one, multiorgan failure in one). Early mortality was influenced by the severity of preoperative congestive heart failure, the severity of left ventricular dysfunction and the date of operation. Mean follow-up was 116±78 months (range 3 months to 20 years). There were two sudden deaths at three and seven months. Global left ventricular function recovered to normal in all survivors. Five patients underwent reoperation (three for mitral valvuloplasty, one for surgical angioplasty of the reimplanted left coronary artery and one for mammary bypass).
Surgical technique Simple ligation of the anomalous coronary artery has been the first procedure to be used; this cannot be recommended because of high early and late mortality rates. Various procedures have been described to revascularize the anomalous artery using saphenous vein, mammary artery or left subclavian artery. They all have been abandoned except the mammary artery which may be used as a bypass in adult patients when direct aortic reimplantation is deemed technically difficult. The Takeuchi procedure involves creation of a fistula between the aorta and the pulmonary artery and construction of a tunnel within the pulmonary artery to direct blood flow from the aorta to the anomalous coronary ostium [4]. Late complications are not uncommon including progressive stenosis of the intrapulmonary coronary tunnel, aortic valve insufficiency, baffle leak creating coronary–pulmonary artery fistula and supravalvar pulmonary stenosis [5, 6, 7, 8]. This procedure cannot be recommended anymore. The development of the arterial switch operation for transposition of the great arteries has shown that manipulating the coronary arteries was feasible even in infants and neonates. Therefore, direct aortic reimplantation of the anomalous left coronary artery has become the procedure of choice. In most cases, the anomalous ostium is arising from the left posterior sinus; aortic reimplantation is usually technically easy. It is crucial to select the ideal site of reimplantation in order to avoid any kinking at the anastomotic site. Opening the ascending aorta provides excellent exposure to achieve this goal. In unusual situations (origin from another pulmonary sinus, pulmonary trunk or right pulmonary artery), technical modifications allow aortic reimplantation [9]. The only situation in which coronary transfer is impossible is represented by anomalous origin from the right pulmonary artery with an intramural aortic course; in this condition, creation of a neo-left coronary ostium is recommended [3].
Indications
Results Global left ventricular function always improves but normalization of left ventricular function may take several months. Recovery is more rapid and more complete when surgery is performed early to reduce the duration of the initial ischemic insult. Although postoperative normalization of left ventricular function is the rule, some degree of chronic impairment may persist definitively (Table 1, [6, 7, 8, 10, 11, 12, 13, 14, 15]).
Along with left ventricular function improvement, mitral regurgitation, if present, always decreases. In many cases, it even disappears completely. This is the reason why attempting to repair the mitral valve at the time of the initial operation cannot be recommended. However, recovery of normal mitral valve function is usually less rapid than that of left ventricular function. It may even be incomplete and significant mitral regurgitation due to irreversible ischemic damage may persist and need reoperation. When recovery of left ventricular function or improvement in mitral valve regurgitation are slow and incomplete, the suspicion of inadequate coronary revascularization should be raised, which needs to be confirmed by coronary angiography. Stenosis or occlusion of the reimplanted coronary artery may then lead to reoperation.
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