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Anomalous left coronary artery
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Pathophysiology
Anomalous left coronary artery is a rare congenital cardiac anomaly in which the left coronary artery arises from the pulmonary artery. The exact site of origin varies, but most frequently the origin is from the proximal main pulmonary artery. During the early postnatal period, elevated pulmonary vascular resistance results in antegrade perfusion of the anomalous coronary artery with desaturated blood. As pulmonary vascular resistance drops during the first few weeks of life, blood shunts retrograde from the anomalous coronary artery into the pulmonary artery. This abnormal blood flow pattern results in decreased perfusion to the left coronary artery system. Decreased myocardial blood supply leads to left ventricular ischemia, and left ventricular failure ensues. Left ventricular dilatation results in mitral insufficiency. Anomalous origin of the left coronary artery must be ruled out in any patient who presents with severe left ventricular dilatation and mitral insufficiency in the first few months of life.
Surgical technique
The goal of surgical repair of anomalous origin of the left coronary artery is to reestablish a two coronary artery system. Cardiopulmonary bypass and aortic cross clamping are required for repair of this defect. Technique for repair varies, but reimplantation of the anomalous coronary artery into the aortic root is performed whenever possible (not shown). Another innovative technique used for repair of anomalous left coronary artery is depicted here. In this technique, an aortopulmonary window is created, and a flap using the anterior wall of the pulmonary artery is made. The flap of anterior pulmonary artery wall is then sutured into place along the posterior pulmonary artery, creating a tunnel that directs aortic blood flow to the orifice of the anomalous coronary ostium. The deficiency left in the anterior wall of the pulmonary artery is then repaired with a patch. Alternatively, a patch of synthetic material or cryopreserved homograft may be used to create thebaffle. Transesophageal echocardiography is used to help assess adequacy of repair. Aortic cross-clamp time and cardiopulmonary bypass time required for this procedure are moderate.
Postoperative considerations
The postoperative course following repair of anomalous left coronary artery is often difficult. Ventricular dysfunction and mitral insufficiency prior to surgery often result in hemodynamic instability in the early postoperative period. Invasive monitors used include arterial and central venous catheters. An LA line is used when needed for hemodynamic management. LA pressure acts as a surrogate for left ventricular end diastolic pressure, an excellent indicator of left ventricular performance. Non-invasive monitors include NIRS (near-infrared spectroscopy) probes to assess adequacy of regional and global perfusion and traditional pulse oximetry. Vasoactive agents might include epinephrine and/or milrinone. Numerous other agents are available and are tailored to the specific needs of the patient, targeting adequate oxygen delivery to the tissues of the body and optimization of cardiac output. Infusions of fentanyl and a neuromuscular blocking agent are used for sedation. Postoperative ventricular support in the form of extracorporeal membrane oxygenation (ECMO) is sometimes required in severe cases of depressed cardiac output. Following repair of anomalous left coronary artery, gradual improvement in ventricular function is the rule.Postoperative arrhythmias are occasionally encountered following this repair. Excessive bleeding is an uncommon complication. With improvement in ventricular function and resolution of left atrial dilatation, intracardiac pressures and oxygen saturations should return to normal. Length of hospital stay varies depending on preoperative myocardial function and postoperative course. Ten days to three weeks is average.