Aortic and pulmonary stenosis — formative SAQs

SAQ 1 (10 marks) — The collapsed neonate

Stem: A three-day-old term infant presents to the emergency department with poor feeding, grey pallor, weak pulses, tachypnoea, and a capillary refill of five seconds. The blood gas shows a pH of 7.10 with a lactate of 8 mmol per litre. A harsh systolic murmur is heard at the upper right sternal border. Discuss the immediate management, the likely diagnosis, and the definitive intervention. [3] [2]

Model answer

Recognise duct-dependent critical aortic stenosis and start prostaglandin E1 (3 marks). The clinical picture — a neonate in the first week of life with shock, poor perfusion, weak pulses, and a metabolic acidosis — is the classic presentation of a duct-dependent left-heart obstruction. Critical aortic stenosis is the leading diagnosis, though coarctation and hypoplastic left heart syndrome are in the differential. Start prostaglandin E1 at 0.01 to 0.05 mcg per kg per minute immediately, without waiting for echocardiographic confirmation, because the cost of unnecessary prostaglandin is far lower than the cost of a missed duct-dependent lesion. Secure the airway, because prostaglandin-induced apnoea is common. [3]

Stabilise and investigate (2 marks). Obtain venous access, check blood gas and lactate, start inotropes if myocardial dysfunction is present, and arrange urgent echocardiography. The echocardiogram confirms the level of the obstruction (valvar, subvalvar, or supravalvar), the severity (peak gradient), the left-ventricular size and function, and any associated lesions. Four-limb blood pressures and pre- and post-ductal saturations are checked to narrow the differential. [3]

Definitive intervention — balloon aortic valvuloplasty (3 marks). Once stabilised on prostaglandin, the definitive intervention for critical valvar aortic stenosis is balloon aortic valvuloplasty, performed urgently by the interventional cardiologist. The balloon is advanced across the stenotic valve and inflated to split the fused commissures and reduce the gradient. The VACA Registry data established the predictors of success and the complication profile, with aortic regurgitation as the main concern. If the left ventricle is too small or hypoplastic to support the systemic circulation, a single-ventricle (Norwood) pathway may be needed instead. [4]

Long-term surveillance and family screening (2 marks). After successful intervention, the child needs lifelong cardiology follow-up for restenosis, aortic regurgitation, and aortic root dilation. Bicuspid aortic valve is the commonest underlying cause and is familial with autosomal dominant inheritance, so first-degree relatives should be screened with echocardiography. Structured transition to adult congenital heart disease services begins in early adolescence. [1]

SAQ 2 (10 marks) — The upper-left-sternal-border murmur

Stem: A four-year-old child is referred by the general practitioner after a systolic murmur was heard at the six-month check. On examination, there is an ejection systolic murmur at the upper left sternal border radiating to the back, with a widely split second heart sound and an ejection click that varies with respiration. The child is asymptomatic and growing normally. The echocardiogram shows a peak gradient of 55 mmHg across a domed pulmonary valve with fused commissures. Discuss the classification, the severity grading, and the management. [5] [2]

Model answer

Classification — valvar pulmonary stenosis (2 marks). The lesion is classified by anatomic level as valvar, because the ejection click localises the obstruction to the valve and the echo confirms a domed valve with fused commissures at the pulmonary valve level. The widely split second heart sound reflects delayed pulmonary valve closure from prolonged right-ventricular ejection, and its width correlates with severity. The respiratory-varying click is characteristic of pulmonary valve origin, distinguishing it from the fixed aortic click heard at the apex. [1]

Severity grading — moderate (2 marks). The severity is graded by the echocardiographic peak systolic gradient: mild below 40 mmHg, moderate 40 to 64 mmHg, and severe above 64 mmHg. This child's gradient of 55 mmHg places the lesion in the moderate category, which is the threshold for referral to the interventional cardiologist. The child is currently asymptomatic, which is typical of moderate pulmonary stenosis, because the right ventricle adapts with hypertrophy that preserves function for years. [5]

Management — balloon pulmonary valvuloplasty (4 marks). Balloon pulmonary valvuloplasty is the first-line and definitive intervention for valvar pulmonary stenosis and is one of the most successful procedures in congenital interventional cardiology. The long-term outcome data show sustained gradient reduction with low rates of restenosis and a low complication rate. The procedure is indicated for moderate and severe gradients and for symptomatic disease. The dysplastic Noonan valve is the main exception — it responds poorly to ballooning and usually needs surgical valvotomy, but this child's domed commissural-fusion valve is the classic indication. [5]

Surveillance and counselling (2 marks). After successful balloon valvuloplasty, the child needs serial echocardiography for restenosis and pulmonary regurgitation, which is usually well tolerated in childhood but may require pulmonary valve replacement in adulthood. The child can return to normal activities, including competitive sport, once the gradient is reduced. The family is counselled that the prognosis is excellent and that lifelong cardiology follow-up is expected, with structured transition to adult congenital heart disease services in adolescence. [1] [5]