Congenital coronary anomalies and ALCAPA — branching viva

Examiner opening (Examiner)

You are the general paediatric registrar in the emergency department. A ten-week-old infant is brought in with pallor, sweating and irritability during feeds, poor weight gain, and increasing breathlessness. He has a gallop rhythm, a pansystolic murmur at the apex, and hepatomegaly. The electrocardiogram shows deep Q waves in the anterolateral leads. Talk me through your assessment and immediate management. [1] [2]

Exemplar opening (Candidate)

This infant has heart failure with a presentation that is highly suggestive of anomalous left coronary artery from the pulmonary artery, and I will move quickly because this is a surgical emergency. The feeding-related pallor, diaphoresis and irritability are the anginal equivalents of infancy, and the anterolateral Q waves on the electrocardiogram reflect the anterolateral infarction that characterises ALCAPA. I will examine for the degree of heart failure and perfusion, take blood for a troponin, full blood count and gases, and arrange an urgent echocardiogram with the explicit request to demonstrate the origin and proximal course of both coronary arteries. While I wait for imaging I will start oxygen, give intravenous furosemide, begin gentle afterload reduction, and involve the paediatric intensive care and cardiology teams, because the definitive treatment is surgery to re-establish a dual coronary system. [1] [2]

Branch 1 — the diagnosis and the steal (Examiner)

What is ALCAPA, and why does it declare itself at two to three months rather than at birth? [1]

Exemplar (Candidate)

ALCAPA is the left coronary artery arising from the pulmonary artery rather than the aorta, also called Bland-White-Garland syndrome. In fetal life and the early neonatal period the pulmonary vascular resistance is high and the pulmonary artery pressure is close to systemic, so blood flows forward from the pulmonary artery into the misoriginated left coronary artery and the left ventricle is protected — though perfused with desaturated blood. As the pulmonary vascular resistance falls over the first weeks of life, the pressure gradient reverses, the left coronary artery drains into the low-pressure pulmonary artery, and the left ventricle is left to be supplied only by collaterals from the right coronary artery at low pressure. The myocardium infarcts at around two to three months, which is why the symptoms appear then rather than at birth. [1]

Branch 2 — investigations and the differential (Examiner)

How will you confirm it, and what is the main differential you must exclude? [2]

Exemplar (Candidate)

The electrocardiogram already carries a near-diagnostic pattern: deep Q waves in leads I, aVL and the left precordial leads with ST and T-wave change, reflecting the anterolateral infarction. The cornerstone is echocardiography, which must show the left coronary artery arising from the pulmonary artery with retrograde colour-Doppler flow into the pulmonary artery, a dilated poorly contracting left ventricle, and mitral regurgitation. If echo is equivocal I would use computed tomography coronary angiography to confirm the origin and course. The main differential is dilated cardiomyopathy of metabolic, genetic or post-viral cause, which produces an identical big floppy ventricle clinically — only the demonstration that the left coronary comes from the aorta separates them. Myocarditis and sepsis are the acute mimics, and colic, reflux and bronchiolitis are the benign mimics that delay diagnosis. The principle is that no infant dilated cardiomyopathy is idiopathic until the coronary origin is shown. [2]

Branch 3 — acute stabilisation (Examiner)

The infant is in cardiogenic shock. How do you stabilise him? [3]

Exemplar (Candidate)

Stabilisation is a bridge to surgery. I will support the airway and breathing with oxygen and positive-pressure ventilation if the work of breathing is high, and treat the heart failure with intravenous furosemide and an afterload reducer such as an angiotensin-converting-enzyme inhibitor, recognising that the failing ventricle is afterload-dependent. In intensive care I will add inotropes such as milrinone and low-dose adrenaline for low cardiac output, correct any metabolic acidosis, and treat arrhythmia. For the infant who cannot be stabilised on inotropes I will use mechanical circulatory support with extracorporeal membrane oxygenation as a bridge to surgery and to recovery of the stunned ventricle after repair. The goal is to restore the circulation well enough to take the child safely to the operating room. [3]

Branch 4 — definitive surgery (Examiner)

What is the operation, and what governs the long-term outcome? [3] [6]

Exemplar (Candidate)

The definitive treatment is surgical re-establishment of a dual coronary system. The preferred operation is direct reimplantation, in which the left coronary artery is detached from the pulmonary artery with a button of arterial wall and re-implanted into the aorta, restoring antegrade systemic perfusion. Where the anatomy does not allow direct reimplantation, the Takeuchi operation creates an aortopulmonary window and tunnels a flap of pulmonary artery wall to redirect aortic blood into the left coronary ostium. Severe mitral regurgitation is repaired at the index operation, but moderate regurgitation is often deferred because the ischaemic papillary muscles recover once coronary flow is restored. The long-term outcome is driven by the timeliness of repair — earlier repair means better left ventricular recovery — together with residual mitral regurgitation and the burden of ventricular arrhythmia. The ECHSA database and long-term follow-up show good left ventricular recovery and low late mortality with timely repair, and these children need lifelong surveillance with transition to adult congenital care. [3] [6]

Branch 5 — the young athlete (Examiner)

Now switch. A fourteen-year-old footballer collapses with chest pain during a match and his left coronary arises from the right sinus. How does this differ, and what is the danger? [4] [5]

Exemplar (Candidate)

This is anomalous aortic origin of a coronary artery, and the danger is sudden cardiac death, frequently as the first symptom. The coronary arises from the opposite sinus and runs an interarterial, intramural course between the aorta and pulmonary artery with a slit-like ostium. At rest the flow is adequate, so the resting electrocardiogram and examination may be normal, but under the high cardiac output, tachycardia and aortic distension of exercise the intramural segment is compressed and the ostium deforms, producing exertional ischaemia and malignant arrhythmia. A left coronary from the right sinus carries the highest risk because it supplies the whole left ventricle, which is why the surgical threshold is far lower than for a right coronary from the left sinus. My immediate management is to restrict exercise, arrange computed tomography coronary angiography and exercise testing, and refer urgently to a congenital cardiologist for a surgical decision. [4] [5]

Branch 6 — exercise and shared decisions (Examiner)

The family want him back in the team. How do you counsel them? [4] [5]

Exemplar (Candidate)

I would acknowledge how much the sport means to him and be honest about the risk: the lesion carries a real risk of sudden death with competitive exercise, and an ischaemic event in the territory of a left coronary is usually fatal. The decision to operate, restrict or clear must be shared, evidence-based, and made with a congenital cardiologist. For a left-sided interarterial lesion the consensus generally favours surgery, after which many athletes return to play under a structured supervised protocol. For a right-sided lesion without symptoms or ischaemia, exercise restriction and surveillance is an option, carrying a small residual risk. I would explain the surgery and the surveillance plan, address the psychological cost of restriction, and give the family a clear contact in the congenital service, because the long-term decisions are subspecialty decisions. [4] [5]

Examiner wrap-up (Examiner)

Thank you. Summarise the three points you most want the examiner to remember. [1] [4]

Exemplar (Candidate)

First, ALCAPA presents at two to three months with feeding-related pallor and anterolateral Q waves, and the mechanism is the steal as pulmonary vascular resistance falls; the left coronary origin must be shown before any infant dilated cardiomyopathy is called idiopathic. Second, ALCAPA is a surgical emergency — direct reimplantation or the Takeuchi tunnel re-establishes dual coronary flow, and earlier repair means better left ventricular recovery. Third, exertional syncope or chest pain in a young athlete is a coronary anomaly until proven otherwise, and an interarterial left coronary from the right sinus carries the highest sudden-death risk and the lowest surgical threshold; never reassure an ischaemic child. [1] [4] [3]