ALCAPA

Summary of ALCAPA

Anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA), also known as Bland–White–Garland syndrome, is a rare but potentially fatal congenital heart condition. It is the primary cause of myocardial ischemia in children. ALCAPA occurs when the left coronary artery (LCA) originates from the pulmonary artery (PA) instead of the aorta. The incidence is approximately 1 in 300,000 live births and it comprises between 0.24% and 0.46% of all congenital heart disease. One unit reported an incidence of about 0.35% of congenital heart diseases. ALCAPA should be suspected and excluded in any pediatric patient presenting with left ventricular dysfunction. In infants, classic presentation includes heart failure symptoms, dilated LV, low ejection fraction, and mitral regurgitation, often with a dilated RCA on echo. Early surgery is necessary for both symptomatic infants and asymptomatic children/adolescents to restore normal circulation and prevent long-term myocardial damage.

Anatomy and Pathophysiology:

• The LCA typically arises from the main pulmonary artery (MPA), usually from the left pulmonary valve sinus, but rarely from a branch pulmonary artery.

• Embryologically, this anomaly may result from the failure of cells of the capillary plexus surrounding the pulmonary artery and aorta to reach the normal coronary origins in the aorta, with concomitant persistence of pulmonary buds.

• In utero, pulmonary and aortic pressures are similar, allowing for relatively normal coronary perfusion.

• Postpartum, as pulmonary vascular resistance (PVR) drops drastically and aortic pressure exceeds PA pressure, blood flows preferentially from the higher-pressure systemic circulation (via the Right Coronary Artery and collaterals) into the lower-pressure pulmonary circulation through the anomalous LCA. This phenomenon is called "coronary steal".

• This retrograde flow leads to reduced coronary perfusion and myocardial ischemia in the territory supplied by the LCA. The low perfusion pressure is considered the primary cause of serious problems seen in ALCAPA.

Types and Presentation: 

ALCAPA is typically classified into two types based on age of presentation, which is largely determined by the development of coronary collaterals:

• Infant Type (approximately 85%): These infants have little to no collateral development. As pulmonary artery pressure falls after birth, they develop severe myocardial ischemia. Presentation is usually around 2–3 months of age with symptoms of congestive heart failure. Symptoms may include dyspnea, tachypnea, prolonged or difficult feeding, pallor, diaphoresis, delayed development, and failure to thrive. Infants may also present with sudden, unexplained crying or screaming in the setting of heart failure. Physical examination may reveal varying degrees of mitral regurgitation (MR) and left ventricular (LV) dysfunction. MR can be functional due to LV dilation or a result of papillary muscle ischemia. Untreated, infant mortality is reported to be as high as 90% in the first year of life. Many of these infants have bright (echogenic) papillary muscles and bright LV myocardium with ischemia on echocardiography, they can present severe LV dysfunction.

• Adult Type (approximately 15%): These patients survive infancy due to the development of large, extensive inter-coronary collaterals, often from a dominant RCA. They may remain asymptomatic until childhood or adulthood. Symptoms in older children/adults, when present, include palpitations, syncope, dyspnea, chest pain, and fatigue. This type is a well-known cause of sudden cardiac death in adults. There is an estimated 80% to 90% incidence of sudden death at a mean age of 35 years in those who survive past childhood. Survival beyond 50 years of age without repair is very rare.

Associated Lesions: 

ALCAPA usually occurs in isolation. However, it can be associated with other congenital heart diseases such as atrial septal defect (ASD), ventricular septal defect (VSD), patent ductus arteriosus (PDA), Tetralogy of Fallot (TOF), aorto-pulmonary window, and coarctation of the aorta (CoA).

Diagnostic Evaluation: 

Prompt diagnosis is crucial for guiding surgical intervention and improving prognosis.

• Echocardiography: This is the diagnostic imaging modality of choice. It is safe, readily available, inexpensive, and portable for initial investigation. Key findings include:

  • Direct visualization of the LCA originating from the PA.

  • Retrograde flow from the LCA into the PA, particularly noted by color Doppler in diastole.

  • A dilated and often tortuous RCA.

  • Difficulty identifying the LCA arising from the aorta.

  • Significant collateral coronary arteries, sometimes seen in the interventricular septum. Pulse-wave Doppler can differentiate continuous flow in collaterals from systolic flow in VSDs.

  • Mitral regurgitation and left ventricular dysfunction.

  • Echogenic myocardium or papillary muscles.

  • Abnormal diastolic flow entering the PA.

  • The parasternal short-axis view provides the best views of the coronary origins.

  • Echocardiography can make an early diagnosis, including in asymptomatic patients. Suspect ALCAPA when echo shows a large RCA or retrograde flow in the LCA. Limitations include poor spatial resolution and difficulty visualizing the anomalous origin.

• Electrocardiogram (ECG): ECG findings suggestive of ALCAPA include abnormal deep or wide Q waves, inverted T waves, and poor R wave progression in leads I, aVL, and precordial leads V4 to V6. Left ventricular hypertrophy and myocardial injury patterns may also be present. ECG changes were observed in 77.8% of patients aged 5-16 years in one study.

• Chest X-ray (CXR): May show marked cardiomegaly and pulmonary congestion. Enlarged LA and LV may be suggested. Cardiomegaly was present in 77.8% of patients in one series.

• Cross-sectional Imaging (Computed Tomography Angiography - CTA or Magnetic Resonance Angiography - MRA): These modalities provide superior visualization of the coronary arteries compared to echo and can be used for definitive diagnosis, anatomical assessment, and postoperative follow-up. Findings include direct visualization of the LCA originating from the PA, dilated RCA with collaterals, and abnormal LV wall movement. CMR can also assess ventricular size and function. Used for older children or when echo findings are uncertain.

• Cardiac Catheterization (Angiography): While not routinely used for initial diagnosis now, angiography can corroborate the diagnosis. It shows the dilated, tortuous RCA, collaterals to the LCA, and anomalous flow into the PA. Angiography provides detailed visualization of collaterals and can quantify left-to-right shunts. Some sources still recommend corroborating echo findings with angiography. It can help differentiate ALCAPA from other lesions like a coronary fistula to the PA.

• Non-invasive Ischemic Evaluation: Tests like cardiopulmonary exercise testing, stress echocardiography, and myocardial stress perfusion can reveal ischemia.

Management: 

Surgical intervention is the recommended treatment for ALCAPA patients regardless of age and symptoms due to the lifelong risk of ischemia, ventricular dysrhythmias, and sudden cardiac death. The modern objective of surgery is to reestablish a dual coronary system that provides oxygenated blood to the heart.

• Surgical Approaches: Various techniques have been used, including direct reimplantation of the coronary artery into the aorta (coronary button transfer), transpulmonary baffling (Takeuchi technique), subclavian-LCA anastomosis, and coronary artery bypass grafting (CABG) with ligation of the anomalous LCA. Direct reimplantation and its modifications are common modern methods. The Takeuchi technique involves creating an intrapulmonary baffle. CABG is often used in older patients where direct reimplantation is difficult.

• Older Methods: Simple ligation of the anomalous artery was used in the past. While potentially used to delay more intensive surgery in severely ill infants, it is now avoided as an exclusive method due to associated complications, including persistent ischemia and sudden death risk.

• Medical Management: Medications can be used alongside surgery. Preoperative drug treatment may be used in infants with acute myocardial ischemia to help recover cardiac function. In rare high-risk adults, medication might be used instead of surgery.

• Cardiac Transplantation: This is reserved for patients with severe LV dysfunction and refractory heart failure.

Prognosis and Outcomes: 

With surgical correction, generally positive long-term outcomes with low mortality rates are expected. Long-term survival is excellent, but depends on the recovery of ventricular function and the degree of mitral regurgitation. One study reported an 83.4% Kaplan–Meier survival rate one year post-operation in pediatric patients, with 13.8% hospital deaths. Another series reported 8.5% in-hospital mortality with no late deaths. The 10-year transplant-free survival rate is reported to be 95%. LV function typically recovers, symptoms improve, and MR often ameliorates after surgery. Complete recovery is possible if surgery is performed before irreversible myocardial damage occurs. However, some degree of MR may persist, particularly if severe pre-operatively. Residual MR and LV dysfunction may be more common in those operated on later in infancy. The type of surgical correction has not been found to significantly impact mortality, but different procedures have different complication profiles.

Complications: Potential complications after surgical repair include persistent mitral regurgitation, pulmonary artery stenosis (especially with the Takeuchi technique), baffle leaks or obstruction (Takeuchi technique), aortic regurgitation (Takeuchi technique), LCA tearing or bleeding in adults during reimplantation, and graft occlusion or stenosis (CABG). Mitral valve intervention timing is controversial as MR often improves after ALCAPA repair, but may be warranted if severe. Lifelong follow-up with a cardiologist is necessary to monitor for complications.

References

• Blickenstaff EA, Smith SD, Majdalany DE. Anomalous Left Coronary Artery from the Pulmonary Artery: How to Diagnose and Treat. Journal of Personalized Medicine. 2023;13(11):1561. DOI: 10.3390/jpm13111561. https://doi.org/10.3390/jpm13111561.

• Dipchand AI, et al., editors. Manual of Cardiac Care in Children. Springer Nature Switzerland AG; 2024. ISBN: 978-3-031-70973-9. DOI: 10.1007/978-3-031-70973-9. https://doi.org/10.1007/978-3-031-70973-9.

• Ho SY, Rigby ML, Anderson RH. Echocardiography in Congenital Heart Disease Made Simple. Imperial College Press; 2005. ISBN: 1-86094-124-9.

• Archivos de Cardiología de México. Anomalous origin of the Left Coronary Artery from the Pulmonary Artery. Echocardiographic diagnosis. ISSN: 1405-9940, e-ISSN: 1665-1731. Copyright © 2025 Elsevier España SLU. (URL inferred from publisher and journal title: https://www.elsevier.es/es-revista-archivos-cardiologia-mexico-73?bd=1).

• Jinmei Z, Yunfei L, Yongjun Q, yue W. Anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA) diagnosed in children and adolescents. Orphanet Journal of Rare Diseases. 2020;15:90. DOI: 10.1186/s13019-020-01116-z. https://doi.org/10.1186/s13019-020-01116-z.

• Khalid O, Awad S, editors. Pediatric Electrocardiography: An Algorithmic Approach to Interpretation. Springer International Publishing Switzerland; 2016. ISBN: 978-3-319-26256-7 (Print), 978-3-319-26258-1 (eBook). DOI: 10.1007/978-3-319-26258-1.

• Park IS, editor. An Illustrated Guide to Congenital Heart Disease: From Diagnosis to Treatment – From Fetus to Adult. Springer Nature Singapore Pte Ltd.; 2019. ISBN: 978-981-13-6977-3 (Print), 978-981-13-6978-0 (eBook). DOI: 10.1007/978-981-13-6978-0. https://doi.org/10.1007/978-981-13-6978-0.

• Rudolph AM. Congenital Diseases of the Heart: Clinical-Physiological Considerations. 3rd ed. John Wiley & Sons, Ltd. / Wiley-Blackwell; 2009. ISBN: 978-1-405-16245-6. (URL inferred from title, author, and publisher: https://onlinelibrary.wiley.com/doi/book/10.1002/9781444301549).

Case 1

Case 2

Case 3

In this case, one may observe a neonate who presented at two weeks of life with diaphoresis, difficulty feeding, tachypnea and failure to thrive. The patient was found to have ischemic changes on electrocardiogram and severe LV failure by echocardiography. The coronary artery was found to be attached to the pulmonary artery. Here, you will appreciate by colour Doppler the abnormal implantation of the left coronary artery.