Coarctation and interrupted aortic arch — formative SAQs

SAQ 1 — Neonatal collapse on day three (10 marks, 15 minutes)

A three-day-old term infant, previously feeding well, is brought to the emergency department with poor feeding, tachypnoea, mottled skin and oliguria. On examination the baby is shocked with cool peripheries, a heart rate of 180, a respiratory rate of 70, and a capillary refill of five seconds. The brachial pulses are strong but the femoral pulses are weak and delayed. Pre-ductal (right arm) saturation is 95% and post-ductal (leg) saturation is 72%. The blood gas shows a pH of 7.10 with a base excess of minus twelve and a lactate of 8 mmol per litre. A ductal-dependent arch obstruction is suspected. [4]

a) What is the most likely diagnosis, and what single bedside sign makes it most likely? (2 marks) [3]

b) Outline your immediate resuscitation, including the specific drug, its dose and its mechanism of action. Name the most important side effect and how you would manage it. (5 marks) [4]

c) Explain the pathophysiology of why this child was well for three days and then collapsed. (3 marks) [3]

SAQ 2 — Adolescent girl with coarctation and Turner syndrome (10 marks, 15 minutes)

A fourteen-year-old girl is referred for investigation of hypertension found at a school health check. Her blood pressure is 150/90 in the right arm and 148/92 in the left arm, but only 110/70 in both legs. Her femoral pulses are weak with radio-femoral delay. She is on the third centile for height, with a webbed neck, widely spaced nipples and a low posterior hairline. An echocardiogram confirms a juxtaductal coarctation with a bicuspid aortic valve. [9]

a) What is the significance of the four-limb blood-pressure findings, and what additional genetic investigation is now essential and why? (3 marks) [9]

b) Outline the surgical management of the coarctation and the role of balloon angioplasty in this age group. (4 marks) [10]

c) Describe the lifelong follow-up this patient will need, including the cardiovascular and non-cardiovascular considerations. (3 marks) [11]