EXPLANATION


An anomalous left coronary artery from the pulmonary artery (ALCAPA) is a rare lesion, with an incidence of 1 per 300,000 births. It is also known as Bland-White-Garland syndrome, named after the first clinical description in 1933. Normally, left ventricular (LV) perfusion occurs during ventricular diastole as ventricular systole limits coronary blood flow. In patients with ALCAPA, left ventricular perfusion occurs with mixed venous blood originating from the pulmonary artery due to elevated pulmonary vascular resistance (PVR) over the first weeks of life. However, once PVR and pulmonary artery (PA) pressure begin to decrease over the first several weeks of life, myocardial perfusion also decreases as coronary perfusion pressure and coronary blood flow decrease. This may lead to a reversal in blood flow in the ALCAPA, leading to a “coronary steal phenomenon” and further increasing the risk of LV ischemia and dysfunction. The right ventricle (RV) remains somewhat protected from ischemia as myocardial perfusion occurs in both systole and diastole. Progression of LV dysfunction will eventually lead to LV dilation and impaired RV filling from interventricular septal shift. Mitral valve regurgitation may also ensue, secondary to annular dilation or papillary muscle ischemia. Mitral regurgitation increases volume load to the LV, thus exacerbating dysfunction and pulmonary congestion. Like other dilated or ischemic cardiomyopathies, patients with ALCAPA are at high risk for ventricular arrhythmias.


The presentation of ALCAPA will vary amongst individuals in terms of symptoms and timing. This is mostly due to variations in coronary artery anatomy. A dominant right coronary artery (RCA) will supply a greater proportion of myocardial blood flow and is more likely to result in a later onset of symptoms with less ventricular dysfunction. Stenosis of the ALCAPA might also be beneficial as it reduces coronary steal and favors collateralization from the RCA to the LCA territory, which may minimize myocardial ischemia. A study by Straka et al compared the presentation and outcome of patients with ALCAPA diagnosed in infancy to those diagnosed later in childhood. Most patients who presented in infancy were between two to six months of age, and 62.5% had heart failure as the primary symptom. As expected, most patients had LV dysfunction, LV dilation, and moderate or severe mitral regurgitation. Patients who presented later were more likely to be asymptomatic (62.2%) or have chest pain (20.8%) with preserved LV function. One patient in that group presented with cardiac arrest.


Treatment consists of re-establishing aortic perfusion to the ALCAPA. It is usually done by reimplantation of the coronary artery to the aorta. The Takeuchi procedure, an alternative surgical technique which can be used in the setting of a short ALCAPA segment, creates an aorto-pulmonary window and an intra-pulmonary baffle from the aorta to the ALCAPA. The study by Stratka and colleagues demonstrated that the early group had surgery between one and three days after diagnosis and that 31.1% required mitral valve repair for more than moderate regurgitation.


Anesthetic considerations in the pre-bypass phase include maintaining systemic blood flow in the face of potentially severe LV dysfunction and adequate coronary perfusion pressure to the ALCAPA, while avoiding excessive tachycardia to minimize myocardial oxygen consumption. Induction is high risk and should be done in a slow, titrated manner. These patients are also at high risk for arrhythmias such as ventricular fibrillation due to myocardial ischemia, such that defibrillation or rapid institution of cardiopulmonary bypass may be required. Finally, maintaining a relatively elevated PVR will promote perfusion to the ALCAPA. Therefore, maintaining a moderately elevated PaCO2 and limiting the inspired oxygen concentration will achieve an elevated PVR. After repair, myocardial recovery is not immediate, and patients are likely to require high doses of vasoactive medications or mechanical circulatory support.


Surgical outcomes are generally excellent but are less favorable in those who present at a younger age. The study by Straka et al demonstrated that only one child in the <1 year of age group died, four (8.9%) required extracorporeal membrane oxygenation, and 29 (64.4%) had delayed sternal closure. However, there was no mortality, no need for mechanical support, and no need for delayed sternal closure in the late onset group. Moreover, hospital length-of-stay was significantly shorter in the late onset group. Interestingly, while the early onset group had more than moderate LV dilation and mitral regurgitation at discharge, these parameters were no longer significant at the one-year follow-up. An additional retrospective analysis of surgical outcomes by El-Louali et al that compared patients with an early onset to a late onset of symptoms demonstrated that early onset patients had a significantly more severe clinical presentation and LV dysfunction, higher incidence of delayed sternal closure, longer duration of mechanical ventilation and longer ICU lengths of stay.


ALCAPA and dilated cardiomyopathy have very similar clinical presentations in the infant population. However, the echocardiographic findings described in the stem are highly suggestive of ALCAPA. Dilated cardiomyopathy is more likely to present with echocardiographic findings of biventricular enlargement and clearly delineated coronary ostia. Kawasaki disease may give rise to coronary anomalies in the form of aneurysms and may lead to myocardial ischemia, but the absence of a viral prodrome and typical rash along with the lack of coronary aneurysms make this diagnosis less likely.


REFERENCES


McKenzie I, Zestos MK, Stayer SA, Kaminski E, Davies P, Andropoulos DB. Anesthesia for Miscellaneous Cardiac Lesions. In: Andropoulos DB, Mossad EB, Gottlieb EA, eds. Anesthesia for Congenital Heart Disease. Fourth edition. John Wiley & Sons, Inc.; 2023: 795-800.


Straka N, Gauvreau K, Huang Y, et al. Analysis of Perioperative and Long-Term Outcomes Among Presentations of Anomalous Left Coronary Artery from the Pulmonary Artery Diagnosed Beyond Infancy Versus During Infancy. Pediatr Cardiol. Published online December 15, 2023. doi:10.1007/s00246-023-03344-1


El-Louali F, Lenoir M, Gran C, Allary C, Fouilloux V, Ovaert C. Early Presentation of Patients with Abnormal Origin of Left Coronary Artery from the Pulmonary Artery is a Predictor of Poor Mid-term Outcomes. Pediatr Cardiol. 2022;43(4):719-725. doi:10.1007/s00246-021-02777-w