Graphic by chd_doodles (Yaeji Kim)

Fantastic series of graphics by CHD_Doodles (Yaeji Kim) explaining ALCAPA. Huge thanks for sharing these with the NeoCardioLab community — they are clear, creative, and incredibly educational. Be sure to check out her work on Instagram!

Of note, the “steal” mechanism refers to high-pressure, oxygenated blood from the RCA flowing through collateral vessels to the LCA. Rather than adequately perfusing the myocardium, this blood follows the path of least resistance—retrograde through the LCA and into the low-pressure pulmonary artery. For illustrative purposes, the flow was depicted in blue; however, the blood is in fact oxygen-rich, as the RCA originates from the aorta. Many thanks to Dr. Wernovsky for highlighting this important clarification.

Summary of ALCAPA

Although coronary artery abnormalities are commonly described as anomalies of "origin", the term anomalies of connection is embryologically more precise. The coronary arteries develop from a vascular plexus that subsequently connects to the aortic root rather than arising outward from the aorta.

Anomalous origin/connection 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.

While it was first reported as a specific syndrome in 1933, it has become a standard part of routine pediatric echocardiographic screening since the 1990s. The fundamental issue in ALCAPA is not the delivery of deoxygenated blood to the heart muscle, but rather a change in pressure dynamics that occurs as an infant ages. As the pulmonary vascular resistance drops during the first few weeks of life, the pressure in the pulmonary artery becomes lower than the pressure in the coronary system, leading to a reversal of flow where blood is stolen from the myocardium and drained into the pulmonary artery. This physiological state essentially functions as a large coronary pulmonary fistula, where there is a lack of perfusion during diastole. The resulting myocardial ischemia particularly affects the endocardium and the papillary muscles, which are highly vulnerable because they are supplied by end arteries that do not allow for easy collateralization. This often leads to significant dysfunction of the mitral valve, manifesting as mitral regurgitation, along with global left ventricular dilation and profound contractile dysfunction. In many cases, clinicians will observe endocardial fibroelastosis, which appears as echo brightness or sclerosing of the endocardium and papillary muscles on imaging. Because the papillary muscles are so sensitive to ischemia, brightness in these areas can be a critical diagnostic clue even if the overall ventricular function appears normal. ALCAPA must be recognized in new onset cardiomyopathy at 4-8 weeks of life as it is a surgically addressable condition. 

Coronary Steal:

During fetal life, ALCAPA has no clinical effect because the pressures and oxygen saturations in the aorta and pulmonary artery are almost identical. However, after birth, as pulmonary vascular resistance falls and the arterial duct begins to close, the pressure in the pulmonary artery decreases significantly. AThis drop in pulmonary resistance and pressure causes the perfusion pressure of the anomalous left coronary artery (LCA) to become compromised. As the body attempts to compensate for the resulting myocardial ischemia, large collateral vessels develop on the epicardial surface, connecting the normally positioned, high-pressure right coronary artery (RCA) system to the low-pressure LCA system. The actual "steal" happens because blood entering the LCA from these collaterals follows the path of least resistance into the low-pressure pulmonary artery rather than flowing into the higher-pressure vessels that supply the myocardial capillary bed. This creates a net left-to-right shunt where oxygenated blood is diverted away from the heart muscle and into the pulmonary circulation. This retrograde flow from the left coronary system into the pulmonary artery is most prominent during diastole and is a primary driver of the severe left ventricular dysfunction and heart failure seen in affected infants. Coronary steal is dependent on the development of collateral vessels between the right and left coronary systems. If a patient has not yet developed adequate collaterals, the left coronary artery (LCA) remains dependent on the PA for its perfusion pressure. Because the PA pressure is now much lower than the aortic pressure, the perfusion pressure for the LCA becomes compromised. At this stage, the primary issue is myocardial ischemia because the heart muscle is being perfused with deoxygenated blood at a pressure that is too low to meet its metabolic demands. In this scenario, blood from the PA may reach the LCA but provides poor oxygenation and inadequate pressure, which leads to left ventricular dysfunction and potentially frank infarction. This is generally described as coronary insufficiency rather than "steal". As the body attempts to compensate for this ischemia, large collateral vessels develop on the epicardial surface, connecting the high-pressure Right Coronary Artery (RCA) system to the low-pressure LCA system. The coronary steal occurs specifically at this point: 

• Oxygenated blood from the RCA enters the LCA via these collaterals. 

• Instead of flowing into the high-resistance myocardial capillary bed to provide oxygen to the heart muscle, the blood follows the path of least resistance. 

• The path of least resistance is the low-pressure pulmonary artery. 

• Consequently, blood flows retrogradely (backward) through the LCA and "dumps" into the pulmonary artery.

1. Does steal only happen if there are collaterals? 

   • Yes. Without the "bridge" provided by collaterals, there is no source of high-pressure blood to be "stolen" by the low-pressure pulmonary circuit. Without collaterals, the LCA simply suffers from low inflow and low pressure. 

2. What if there are no collaterals? 

   • If collateral flow is initially insufficient, it results in myocardial ischemia and decreased left ventricular function because the LCA is not being adequately perfused by either the aorta or the PA. 

3. Is blood from the PA going directly to the lungs considered steal? 

   • No. Blood flowing from the PA into the lungs is the normal path of pulmonary circulation. "Coronary steal" specifically refers to blood that has already entered the coronary arterial system being diverted away from the myocardial tissue and into the pulmonary artery. This creates a left-to-right shunt, where blood that should have nourished the heart is "stolen" by the lungs.

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. A unique hallmark in the patient history is feeding-induced colic; parents may report that the child becomes extremely distressed while eating, which is believed to be a form of angina or chest pain triggered by the increased metabolic demands of sucking and swallowing. 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%): While many patients are diagnosed in infancy, some survive longer if they develop extensive collateral circulation between the right and left coronary arteries. These older patients might remain asymptomatic or present with a continuous heart murmur and angina during physical exertion, though they remain at risk for sudden cardiac death. 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: 

To confirm the diagnosis, sonographers look for the hallmark feature of retrograde or reversed color flow within the left coronary artery, where blood moves away from the myocardium and toward the pulmonary artery. Other findings include an enlarged right coronary artery, which dilates to compensate for the collateral burden, and visible color jets entering the pulmonary artery. However, a still frame image can be highly misleading because the thin aortic wall and the close proximity of the vessels can make it appear as though the coronary arises normally from the aorta when it does not. Still frame is not acceptable for evaluations of coronary arteries. Because of the diagnostic challenges, there is a need for humility regarding the fact that echocardiography may not be diagnostic, and a multi-modality approach. If a child presents with a dilated cardiomyopathy and the coronaries appear normal on echo, the diagnosis of ALCAPA must still be pursued through other means, such as CT or MRI, because it represents a potentially reversible form of heart disease. CT and MRI are particularly useful for providing a three-dimensional view and identifying the exact origin and course of the vessels, which can be obscured on ultrasound by artifacts or signal dropout. It is also important to differentiate ALCAPA from rare conditions like congenital atresia of the left main coronary artery, which mimics the clinical appearance of ALCAPA but lacks the retrograde flow into the pulmonary artery.

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.

In summary, the definitive treatment for ALCAPA is surgical intervention, which typically involves the re-implantation of the anomalous coronary artery into the aorta. In cases where the coronary artery is located too far from the aorta to be moved safely, surgeons may perform a Takeuchi procedure, which creates a baffle within the pulmonary artery to direct aortic blood into the coronary orifice. Following surgery, patients require close monitoring to ensure the recovery of left ventricular function and to check for complications like supravalvular pulmonary stenosis caused by the surgical baffle. While most patients show substantial improvement after repair, some may have persistent issues such as papillary muscle fibrosis or subtle myocardial perfusion defects that can be detected during long-term follow-up.

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.

Coronary Artery Anomalies in Newborns and Children

ARCAPA and CALM

Anomalous right coronary artery from the pulmonary artery,

Anomalous right coronary artery from the pulmonary artery, or ARCAPA, is a rare congenital coronary anomaly in which the right coronary artery arises from the pulmonary artery rather than the aorta. Compared with ALCAPA, ARCAPA generally presents later and is less likely to cause profound ventricular dysfunction during early infancy. This difference is related to the generally smaller myocardial territory supplied by the anomalous artery and the frequent development of effective intercoronary collateral circulation, which may partially preserve myocardial perfusion. Nevertheless, neonatal and infantile presentations can occur, and affected patients remain at risk for myocardial ischemia, ventricular dysfunction, arrhythmia, and sudden cardiac arrest. Many patients are asymptomatic at diagnosis or present with a continuous cardiac murmur. Older children and adults may experience exertional chest discomfort, dyspnea, palpitations, syncope, or reduced exercise tolerance. Ventricular dysfunction is uncommon but may occur when collateral perfusion is inadequate or when there is significant coronary steal into the low-pressure pulmonary circulation. A characteristic physiological feature of ARCAPA is the development of collateral vessels from the normally connected left coronary system to the anomalous right coronary artery. As a result, the left coronary artery may become markedly dilated and tortuous because it supplies blood to both coronary systems. Blood then travels through the collateral vessels into the right coronary artery and flows retrogradely toward the pulmonary artery, particularly during diastole. On echocardiography, a disproportionately enlarged left coronary artery and prominent intercoronary collateral vessels should raise suspicion for ARCAPA. The anomalous right coronary artery may be visualized entering the proximal main pulmonary artery in the parasternal long-axis or short-axis view. Colour Doppler may demonstrate retrograde diastolic flow within the right coronary artery and abnormal diastolic flow entering the pulmonary artery. The anomalous connection may be difficult to demonstrate, especially when the right coronary artery arises from the lateral aspect of the main pulmonary artery or from a branch pulmonary artery. Moving two-dimensional clips, colour Doppler, and imaging in multiple planes are required, as still images may falsely suggest a normal aortic origin. Echocardiography can establish the diagnosis when the abnormal connection and flow pattern are clearly demonstrated, but it cannot reliably exclude ARCAPA in every patient. When the clinical or echocardiographic findings remain suspicious, computed tomography angiography or cardiac magnetic resonance imaging should be used to define the exact coronary origin, proximal course, collateral circulation, and relationship to the pulmonary arterial tree. Definitive treatment generally involves surgical restoration of a two-coronary system supplied directly by the aorta.

Congenital atresia of the left main coronary artery (CALM)

CALM syndrome, an acronym for congenital atresia of the left main coronary artery, is an extremely rare coronary anomaly characterized by the absence of a patent left coronary ostium. The proximal left main coronary artery ends blindly and has no functional connection to the aorta. The distal left coronary system, including the left anterior descending and circumflex coronary arteries, is generally present but depends on retrograde perfusion through collateral vessels arising from an enlarged right coronary artery. Because myocardial perfusion depends on collateral circulation, CALM syndrome can cause significant myocardial ischemia and closely mimic the clinical and echocardiographic presentation of ALCAPA. Findings may include marked left ventricular dilation and systolic dysfunction, mitral regurgitation, increased echogenicity of the endocardium and papillary muscles, a dilated right coronary artery, prominent intercoronary collateral vessels, and retrograde flow within the left coronary system. The key distinction from ALCAPA is the absence of an anomalous connection between the left coronary artery and the pulmonary artery. Consequently, CALM syndrome does not produce retrograde coronary flow entering the pulmonary artery. The left main coronary artery instead terminates blindly near the aortic root. Because the abnormality can be difficult to distinguish from ALCAPA using echocardiography alone, additional coronary imaging is usually required. Computed tomography angiography, cardiac magnetic resonance imaging, or occasionally invasive angiography can confirm the absence of a left coronary ostium, demonstrate the blind-ending proximal left main coronary artery, characterize the collateral circulation, and exclude an anomalous origin from the pulmonary artery.

General Principles and Coronary Artery Anomalies Beyond ALCAPA, ARCAPA, and CALM

Congenital coronary artery anomalies encompass a broad spectrum of abnormalities involving the origin, number, position, course, calibre, patency, branching pattern, or termination of the coronary arteries. They may occur in an otherwise structurally normal heart or in association with congenital heart disease. The term coronary artery origin is conventionally used in clinical practice. From an embryological perspective, coronary artery connection is more precise because the developing coronary arteries connect to the aortic root rather than growing outward from it. Both terms are therefore encountered in the literature. The clinical consequences of a coronary anomaly vary considerably. Some variants are incidental and remain asymptomatic throughout life. Others interfere with myocardial perfusion, complicate cardiac surgery or transcatheter intervention, cause myocardial ischemia or ventricular dysfunction, or increase the risk of ventricular arrhythmia and sudden cardiac arrest. ALCAPA, ARCAPA, and congenital atresia of the left main coronary artery, or CALM, are discussed in dedicated sections above on this page and are not repeated here.

Classification

Coronary artery anomalies can be organized into four broad categories. Anomalies of origin include origin from the pulmonary arterial circulation, origin from the inappropriate aortic sinus, direct connection to a cardiac chamber, a single coronary artery, multiple coronary ostia, and an abnormally high or tangential aortic origin. 

• Intrinsic coronary abnormalities include ostial or proximal stenosis, coronary atresia, hypoplasia, absence of a coronary artery, ectasia, aneurysm, calcification, and thrombosis.

• Abnormal coronary courses include interarterial, intramural, intraseptal, intraconal, intramyocardial, prepulmonary, retroaortic, and subendocardial courses. Myocardial bridging is also included in this category.

• Abnormal coronary communications include coronary artery fistulas, coronary cameral fistulas, coronary pulmonary fistulas, and ventriculo-coronary connections or sinusoids.

Importance of systematic coronary assessment

The coronary arteries should be assessed as part of every comprehensive neonatal and pediatric echocardiogram. This assessment is particularly important in newborns, infants, and children with unexplained ventricular dysfunction, myocardial ischemia, mitral regurgitation, congenital heart disease requiring surgery, exertional symptoms, or a personal or family history of sudden cardiac arrest. Coronary arteries are small structures located near several highly reflective interfaces. Echocardiographic dropout from the thin aortic wall can create the false impression that a coronary artery arises normally from the aorta. Conversely, an adjacent structure or the transverse pericardial sinus may be mistaken for a coronary artery. A still image is therefore insufficient to establish coronary anatomy. Coronary origins and proximal courses should be documented using moving two-dimensional clips, colour Doppler, multiple imaging planes, and complete sweeps through the aortic root and great arteries. PW-Doppler should even be considered to evaluate timing of flow in the structure designated as "coronary". Echocardiography is an excellent first-line screening modality and may establish the presence of a coronary anomaly. However, it cannot reliably exclude every coronary abnormality. When the clinical presentation, ventricular phenotype, electrocardiogram, or indirect echocardiographic findings suggest a coronary disorder, apparently normal coronary origins on echocardiography should not end the investigation.

Normal echocardiographic appearance

In a heart with normally related great arteries, the right coronary artery arises from the right aortic sinus and courses anteriorly toward the right atrioventricular groove. The left main coronary artery arises from the left aortic sinus and divides into the left anterior descending and circumflex coronary arteries. The parasternal short-axis view at the level of the aortic root is generally the principal view for examining the coronary origins. Parasternal long-axis, high parasternal, apical, and subcostal views provide complementary information and are particularly useful for tracing proximal and epicardial coronary courses. The imaging sector should be narrowed and the highest appropriate transducer frequency should be used. Colour Doppler settings should be adjusted for low-velocity coronary flow. The colour box can be positioned over the coronary origins, within the myocardium, and between the aorta and pulmonary artery. Coronary perfusion is most prominent during diastole, particularly within the left coronary system.

Indirect evidence of a coronary abnormality

A coronary artery anomaly may first be recognized through its myocardial consequences rather than through direct visualization of the abnormal vessel. Important indirect findings include unexplained global or regional ventricular dysfunction, ventricular dilation, regional wall-motion abnormalities, an ischemic myocardial appearance, increased echogenicity of the papillary muscles, mitral regurgitation, endocardial echogenicity, a disproportionately enlarged coronary artery, extensive epicardial or septal collateral vessels, abnormal diastolic flow within the myocardium, and continuous or diastolic flow entering the pulmonary artery or a cardiac chamber. Multiple colour Doppler signals within the ventricular septum should not automatically be interpreted as muscular ventricular septal defects. Coronary collateral vessels or coronary sinusoids can produce a similar appearance. Spectral Doppler may help distinguish predominantly systolic interventricular shunting from continuous or predominantly diastolic coronary flow.

Clinical red flags

A coronary abnormality should be actively considered in the following situations:

1. Unexplained left or right ventricular dysfunction in a newborn, infant, or child.

2. A dilated cardiomyopathy phenotype, particularly when accompanied by mitral regurgitation or echogenic papillary muscles.

3. Regional ventricular dysfunction or evidence of myocardial infarction.

4. Ischemic electrocardiographic abnormalities or unexplained elevation of myocardial injury biomarkers.

5. A continuous murmur associated with coronary artery dilation.

6. Exertional chest discomfort, exertional syncope, palpitations, unexplained seizure-like collapse, or cardiac arrest.

7. Unexpected hemodynamic instability, ventricular dysfunction, myocardial ischemia, or arrhythmia following congenital heart surgery.

8. Planned surgery or catheter intervention involving the aortic root, pulmonary root, great arteries, or right ventricular outflow tract.

Multimodality imaging

• Echocardiography is usually the first investigation because it is portable, does not use ionizing radiation, and provides simultaneous assessment of ventricular function, valvar function, hemodynamics, and proximal coronary anatomy. 

• Computed tomography angiography provides excellent spatial resolution and rapid three-dimensional delineation of coronary origins, ostial morphology, proximal narrowing, and the relationship of a coronary artery to the aorta, pulmonary artery, myocardium, and cardiac chambers. It is particularly useful when echocardiography cannot confidently define the proximal coronary course.

• Cardiac magnetic resonance can assess coronary anatomy in selected patients while also evaluating ventricular size and function, myocardial viability, scar, perfusion, and inducible ischemia. Its spatial resolution for very small coronary arteries may be more limited than computed tomography, particularly in newborns and young infants.

• Cardiac catheterization is no longer required for the initial diagnosis of most congenital coronary anomalies. It remains valuable when non-invasive imaging is inconclusive, when detailed hemodynamic assessment is required, or when a transcatheter intervention is being considered.

Other anomalous coronary origins from the pulmonary arterial tree

In addition to ALCAPA and ARCAPA, an isolated coronary branch may rarely arise from the pulmonary arterial circulation. Reported variants include anomalous origin of the circumflex coronary artery, the left anterior descending coronary artery, or another coronary branch from the main pulmonary artery or one of its branches. The abnormal origin may be located on the lateral aspect of the main pulmonary artery, the right pulmonary artery, or the left pulmonary artery. These locations can make echocardiographic diagnosis substantially more difficult than when the anomalous coronary artery arises from the proximal main pulmonary artery. The entire main pulmonary artery and the proximal portions of both branch pulmonary arteries should therefore be examined when an anomalous pulmonary coronary origin is suspected. Relevant findings may include dilation of the normally connected coronary system, extensive intercoronary collateral vessels, retrograde diastolic coronary flow, and abnormal diastolic flow entering the pulmonary arterial circulation. When the anomalous origin cannot be demonstrated confidently by echocardiography, computed tomography angiography or another appropriate form of coronary imaging should be performed to define the complete anatomy.

Rare coronary connections to a cardiac chamber

A coronary artery may very rarely connect directly to the right or left ventricular cavity. Coronary perfusion may then depend on ventricular pressure, the timing of ventricular filling, and occasionally the presence of a valve-like fold of tissue near the abnormal connection. These anomalies can produce severe neonatal myocardial ischemia and biventricular or regional ventricular dysfunction. Their anatomy is frequently difficult to define with echocardiography alone and usually requires detailed cross-sectional or angiographic imaging.

Anomalous aortic origin of a coronary artery

Anomalous aortic origin of a coronary artery, or AAOCA, occurs when a coronary artery arises from the inappropriate aortic sinus. The most clinically important configurations are an anomalous left coronary artery arising from the right sinus and an anomalous right coronary artery arising from the left sinus. The anomalous origin alone does not determine clinical risk. The morphology of the coronary ostium and the proximal course of the vessel are essential components of the assessment.

Interarterial course

An interarterial coronary artery travels between the aorta and pulmonary artery. Expansion of the great arteries during physical exertion may contribute to dynamic coronary compression. However, the interarterial position is frequently accompanied by other anatomical abnormalities that may be more important determinants of impaired coronary perfusion.

Intramural course

An intramural coronary artery travels for a variable distance within the wall of the aorta. The intramural segment is frequently narrowed and elliptical rather than circular. It may be associated with an acute takeoff angle and a slit-like or eccentric ostium. Interarterial and intramural are not interchangeable terms. A coronary artery may pass between the great arteries without travelling within the aortic wall, although many high-risk anomalies have both interarterial and intramural components.

Other potentially important anatomical features

Features associated with impaired coronary perfusion include a slit-like orifice, an acute takeoff angle, a tangential origin, an elongated intramural segment, proximal coronary narrowing, an elliptical proximal lumen, an ostial ridge, a course crossing an aortic valve commissure, and marked asymmetry between the proximal and distal calibre of the vessel.

An anomalous left coronary artery from the right sinus with an interarterial or intramural course generally carries greater risk than an anomalous right coronary artery from the left sinus. Management of an anomalous right coronary artery remains more individualized because its absolute risk is lower and surgical intervention can itself produce complications.

Clinical presentation

Many children with AAOCA are asymptomatic. When symptoms occur, they may include exertional chest discomfort, dyspnea, palpitations, dizziness, syncope, seizure-like collapse, ventricular arrhythmia, or cardiac arrest. The absence of preceding symptoms does not exclude a clinically important anomaly.

Ischemic events are commonly associated with physical exertion. Proposed mechanisms include dynamic narrowing of an intramural segment, closure of a slit-like ostium, compression or distortion of an interarterial segment, increased angulation at the coronary origin, and reduced coronary perfusion during periods of increased myocardial oxygen demand.

Echocardiographic assessment

Echocardiography can often identify that a coronary artery arises from the inappropriate sinus and may demonstrate a proximal course between the great arteries. A persistent colour Doppler signal between the aorta and pulmonary artery is an important diagnostic clue. The examination should determine which sinus contains each coronary ostium, whether there appear to be one or two ostia, the direction and angle of takeoff, the relationship to the sinotubular junction, and the course of the coronary artery relative to the aorta and pulmonary artery. Echocardiography is substantially less reliable for determining whether the coronary artery has an intramural segment, measuring the length of that segment, and defining subtle ostial morphology or proximal luminal narrowing. A normal-appearing coronary origin in a single still image should not be considered definitive.

Computed tomography is commonly used to define the complete three-dimensional anatomy. Cardiac magnetic resonance and stress perfusion imaging may provide complementary information regarding myocardial ischemia, scar, and the functional significance of the anomaly.

Management

Management should be individualized by a multidisciplinary team with expertise in congenital coronary artery disease. The coronary artery involved, symptoms, evidence of myocardial ischemia, ostial morphology, proximal narrowing, intramural course, and planned level of physical activity should be considered together. An anomalous left coronary artery arising from the right sinus with high-risk anatomy commonly leads to surgical treatment. Decisions regarding an anomalous right coronary artery arising from the left sinus are more variable and may incorporate symptoms and the results of functional ischemia testing. When an intramural segment is present, surgical unroofing can create a larger coronary opening within the appropriate aortic sinus. Other approaches include coronary reimplantation, ostioplasty, or alternative reconstruction depending on the individual anatomy. Postoperative evaluation should assess coronary patency, residual narrowing, aortic valve function, ventricular function, and evidence of residual or inducible myocardial ischemia.

High coronary takeoff

A high coronary takeoff describes a coronary origin located above the sinotubular junction. It may involve either coronary artery. An isolated high origin is not necessarily pathological. Its significance depends on the associated anatomy. A high takeoff may be accompanied by a tangential ostium, an acute takeoff angle, an intramural segment, proximal narrowing, or an abnormal relationship to the pulmonary artery or one of its branches. Imaging should therefore define the precise ostial height and the complete proximal coronary course rather than simply reporting a high origin.

Single coronary artery and anomalous epicardial courses

In a single coronary artery, the entire coronary circulation arises from the aorta through one ostium. The clinical significance depends on how the coronary branches reach their expected myocardial territories. A coronary branch may pass anterior to the pulmonary artery, behind the aorta, between the great arteries, or through the conal or interventricular septum. A single coronary artery is not inherently high risk, but an associated interarterial, intramural, or severely stenotic segment may be clinically important.

• A circumflex coronary artery arising from the right coronary artery or right aortic sinus usually follows a retroaortic course. This is often an incidental finding but remains important for surgical and interventional planning. 

• A prepulmonary coronary artery passes anterior to the pulmonary artery. An intraseptal or intraconal coronary artery enters the conal or interventricular septum before reaching its usual epicardial territory. On echocardiography, the proximal artery may appear to hang beneath the pulmonary artery, producing the so-called hammock appearance.

• Intraseptal anatomy may be difficult to distinguish from a prepulmonary or interarterial course by echocardiography. Cross-sectional imaging is useful when the course cannot be defined confidently or when symptoms or evidence of myocardial ischemia are present.

Myocardial bridging and intramyocardial courses

A myocardial bridge occurs when a segment of an otherwise epicardial coronary artery travels within the myocardium. The tunneled segment may undergo systolic compression. Most myocardial bridges in children are incidental, although a deep or long bridge may occasionally be associated with myocardial ischemia, chest discomfort, or arrhythmia. An intramyocardial or intraconal coronary course may also have major surgical relevance even when it does not cause spontaneous ischemia. The artery may be difficult to identify or protect during ventricular, septal, or outflow tract surgery.

Subendocardial coronary courses

A coronary artery may rarely travel immediately beneath the endocardial surface of an atrium or ventricle. These courses are usually clinically silent but can create an important risk during intracardiac surgery. A subendocardial right coronary artery along the right atrioventricular groove or a subendocardial circumflex coronary artery may be vulnerable during atrial, atrioventricular valve, or ventricular procedures. Recognition before surgery allows modification of the operative approach.

Coronary artery fistulas

A coronary artery fistula is an abnormal communication between a coronary artery and a cardiac chamber or vascular structure. The receiving site may be the right atrium, right ventricle, pulmonary artery, coronary sinus, left atrium, or left ventricle. The feeding coronary artery is commonly dilated and tortuous. A fistula may have a single drainage site or multiple small communications. Small fistulas are frequently asymptomatic and discovered because of a continuous murmur or an incidental colour Doppler finding. Large fistulas can create a significant left-to-right shunt, chamber dilation, heart failure, coronary steal, myocardial ischemia, coronary aneurysm, thrombosis, arrhythmia, or rarely rupture or infective endarteritis. Echocardiographic evaluation should identify the dilated feeding coronary artery, trace the fistulous pathway when possible, locate the receiving chamber or vessel, characterize the flow pattern, assess chamber enlargement, and evaluate ventricular function. Complete anatomical characterization may be difficult because the fistula can be long, tortuous, and complex. Computed tomography or angiography is often required for procedural planning. Observation, transcatheter closure, and surgical closure are selected according to the size and anatomy of the fistula, symptoms, shunt magnitude, coronary dilation, evidence of myocardial ischemia, aneurysm formation, thrombosis, and the potential effect of closure on normal coronary branches.

Coronary sinusoids and ventriculo-coronary connections

Coronary sinusoids are small communications between the ventricular cavity and the coronary arterial system. They may appear as multiple colour Doppler signals within the myocardium. These communications are particularly important when associated with a hypoplastic ventricle or a coronary circulation that depends on ventricular pressure. Their presence may alter surgical strategy and should prompt careful assessment of coronary perfusion, proximal coronary patency, and the direction of flow through the communications.

Coronary arteries in transposition of the great arteries and double-outlet right ventricle

Coronary anatomy is a central component of the preoperative assessment before an arterial switch operation. The surgeon must transfer the coronary arteries from the native aortic root to the neoaorta. The number of ostia, branching pattern, distance from the valve commissures, proximal course, and relationship to the great arteries can affect the complexity and safety of coronary transfer. The usual pattern consists of the left coronary system arising from one facing sinus and the right coronary artery arising from the other facing sinus. Important variants include a circumflex coronary artery arising from the right coronary artery, a single right coronary artery, a single left coronary artery, inverted coronary origins, and an intramural coronary artery. A coronary artery passing behind the pulmonary artery may represent a circumflex coronary artery arising from the right coronary artery, the entire left coronary system arising from a single right coronary artery, or an inverted left coronary origin. A coronary artery passing anterior to the aorta may represent the right coronary artery arising from a single left coronary system or an inverted right coronary origin. A coronary artery passing between the great arteries raises concern for an interarterial or intramural segment. High parasternal views and complete subcostal sweeps are particularly useful for recognizing these patterns. After an arterial switch operation, follow-up should include assessment of ventricular function, regional wall motion, coronary flow when visible, neoaortic valve function, and evidence of myocardial ischemia. Cross-sectional or functional imaging may be needed when coronary patency cannot be established or when symptoms, ventricular dysfunction, arrhythmia, or electrocardiographic abnormalities develop.

Coronary arteries in tetralogy of Fallot

The most surgically important coronary anomaly in tetralogy of Fallot is a left anterior descending coronary artery arising from the right coronary artery and crossing the right ventricular outflow tract. A coronary artery crossing the outflow tract may limit or prevent a conventional transannular incision and patch. Alternative surgical strategies may include placement of a right ventricle to pulmonary artery conduit or a repair specifically designed to avoid injury to the coronary artery. A prominent conal branch or a dual left anterior descending coronary system can resemble this anomaly. Echocardiography may identify the crossing vessel but may not always define its exact identity or complete course. Coronary anatomy remains important later in life. A coronary artery crossing the right ventricular outflow tract can be compressed during transcatheter pulmonary valve implantation. Coronary compression testing and detailed cross-sectional imaging may therefore be required before intervention.

Coronary arteries in common arterial trunk

The coronary ostia in common arterial trunk can have variable positions relative to the truncal valve and the origin of the pulmonary arteries. The left coronary origin may be displaced posteriorly because the pulmonary arterial component occupies part of the truncal root. The coronary ostia may be slit-like, pinpoint, stenotic, or unusually close to a valve commissure. Bilateral ostial stenosis can cause severe neonatal myocardial ischemia, ventricular dysfunction, or sudden cardiovascular deterioration even before definitive surgical repair. The coronary origins, ostial calibre, proximal course, and relationship to the pulmonary arterial origin should therefore be examined carefully before surgery.

Coronary ostial and proximal stenosis

Congenital ostial stenosis may occur as an isolated lesion or in association with common arterial trunk and other congenital abnormalities. Severe stenosis or atresia can cause myocardial ischemia, ventricular dysfunction, myocardial infarction, arrhythmia, or sudden cardiac arrest. Coronary stenosis can also develop as part of an arterial wall disorder. In Williams syndrome and other elastin arteriopathies, thickening of the aortic root and sinotubular region may narrow or engulf a coronary ostium. Coronary involvement may coexist with supravalvar aortic stenosis and stenoses of other systemic arteries. Generalized arterial calcification of infancy can involve the coronary arteries and produce diffuse calcification, coronary narrowing, myocardial ischemia, and severe cardiac dysfunction. In homozygous or compound heterozygous familial hypercholesterolemia, extensive lipid deposition can affect the aortic root, sinuses of Valsalva, sinotubular junction, valve leaflets, and coronary ostia. Proximal coronary obstruction and supravalvar aortic stenosis may develop during childhood.

Coronary aneurysm and ectasia

Coronary dilation may be congenital or acquired. Kawasaki disease is an important acquired cause of coronary ectasia and aneurysm in children. Large or giant coronary aneurysms are associated with abnormal flow, blood stasis, thrombosis, distal embolization, stenosis during vascular remodelling, myocardial ischemia, and infarction. Echocardiography should evaluate proximal coronary dimensions, aneurysm morphology, luminal appearance, flow, and the presence of possible thrombus. Computed tomography, cardiac magnetic resonance, or angiography may be required when distal coronary segments cannot be evaluated adequately or when thrombosis, stenosis, or myocardial ischemia is suspected.

Neonatal coronary thrombosis

Primary neonatal coronary thrombosis is rare but may cause extensive myocardial infarction and severe ventricular dysfunction. A thrombus can obstruct the proximal branches of an otherwise normally connected coronary artery. The presentation may include sudden cardiovascular collapse, unexplained ventricular dysfunction, regional akinesis, mitral regurgitation, ischemic electrocardiographic abnormalities, elevation of myocardial injury biomarkers, or ventricular arrhythmia. Echocardiography may demonstrate echogenic material within a proximal coronary artery, absent or abnormal coronary flow, and the downstream myocardial consequences. However, the coronary thrombus itself may be difficult to visualize. The underlying cause is not always identified. Diagnosis generally requires integration of echocardiography, electrocardiography, myocardial injury biomarkers, and cross-sectional or angiographic imaging.

Practical echocardiographic checklist

1. Demonstrate both coronary origins using moving two-dimensional clips and colour Doppler.

2. Determine the number of coronary ostia and the sinus from which each coronary artery arises.

3. Assess ostial height, direction, angle of takeoff, and relationship to the sinotubular junction and aortic valve commissures.

4. Trace each proximal coronary artery relative to the aorta, pulmonary artery, ventricular outflow tracts, septum, and myocardium.

5. Look specifically for interarterial, intramural, intraseptal, intraconal, prepulmonary, retroaortic, intramyocardial, and subendocardial courses.

6. Compare the calibre of the right and left coronary systems and search for ectasia, aneurysm, stenosis, hypoplasia, or thrombosis.

7. Search for epicardial, septal, and intramyocardial collateral vessels.

8. Examine the main pulmonary artery and both branch pulmonary arteries for abnormal diastolic coronary flow.

9. Examine the cardiac chambers, coronary sinus, and pulmonary artery for fistulous drainage.

10. Assess global and regional ventricular function, papillary muscle echogenicity, mitral regurgitation, wall-motion abnormalities, and endocardial echogenicity.

11. In congenital heart disease, define the relationship of every important coronary branch to the planned surgical or transcatheter pathway.

12. When the anatomy remains uncertain or indirect findings raise concern, recommend cross-sectional imaging rather than reporting the coronary arteries as normal.

Suggested reporting elements: A complete coronary report should describe the number and location of the coronary ostia, the artery arising from each ostium, the proximal course, the relationship to the great arteries, ostial height and morphology, proximal calibre, suspected narrowing, branching pattern, collateral vessels, fistulous communications, and any associated myocardial consequences. The report should also state whether the coronary anatomy was completely visualized. When the coronary origins or proximal courses are not confidently demonstrated, this limitation should be documented explicitly and additional imaging should be recommended when clinically indicated.

Conclusion

Coronary artery anomalies in newborns and children range from incidental anatomical variants to lesions capable of causing severe myocardial ischemia, ventricular dysfunction, surgical complications, and sudden cardiac arrest. Echocardiography is the essential first-line examination, but confidence in a single image should never replace a systematic evaluation using multiple views, moving clips, colour Doppler, and assessment of indirect myocardial findings. A coronary abnormality may be confirmed by echocardiography, but it cannot always be excluded by echocardiography alone. When the clinical or myocardial phenotype remains suspicious, computed tomography, cardiac magnetic resonance, functional ischemia testing, or angiography should be pursued until the coronary anatomy and its physiological significance are adequately understood.

ECG in ALCAPA

Q waves: 

• Pathologic Qs in I, aVL, V5, V6 Suggest anterolateral infarction pattern (see ECG below).

• Abnormal Qs in infants should raise red flags. These Q waves are deep and wide, supporting anterolateral myocardial injury or infarction, which is common in ALCAPA due to poor perfusion of the left ventricle.

• Deep, narrow, dagger-like Q waves are typically seen in leads I, aVL, and the left precordial leads (V4–V6), often much deeper than physiologic Q waves of healthy infants, with Q waves in V5–V6 and aVL >3 mm considered highly suggestive of ALCAPA.

Chest radiography in ALCAPA Cases

Echocardiographic Example - Case 1 - ALCAPA

Echocardiographic Example - Case 2 - ALCAPA

Echocardiographic Example - Case 3 - ALCAPA

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. 

• Coronaires M3C Academy 2022 Corrélations anatomie et imagerie L. Houyel D. Bonnet - M3C Academy (YouTube) - Français / French

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