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]