Cardiovascular examination and murmur assessment — formative SAQs

SAQ 1 (10 marks)

A four-year-old boy is brought to the clinic because his general practitioner heard a heart murmur at a routine check. He is thriving, asymptomatic and fully active. On examination he is pink and well, with normal brachial and femoral pulses, a blood pressure of 95/55 mmHg in the right arm and 98/58 mmHg in the legs, and an oxygen saturation of 99 per cent in the right hand and 98 per cent in the foot. The apex is undisplaced and non-heaving, there is no thrill, and the heart sounds are normal with a normally split second sound. There is a soft, short, vibratory systolic murmur of grade two at the lower left sternal edge that softens when he sits forward. [1] [4]

a) Describe the murmur, state whether it is innocent or pathological, and give the reasons for your call. (3 marks) [1]

b) Outline the systematic cardiovascular examination you would perform in any child with a murmur, naming the five auscultation areas and the two bedside measurements that must never be omitted. (3 marks) [1] [4]

c) Give the diagnosis, state what further investigation is needed, and explain to the family what the murmur means and the safety-net for return. (2 marks) [1]

d) Contrast this murmur with a pansystolic murmur at the lower left sternal edge in a six-week-old infant, naming the likely lesion and the features that would suggest a large defect and heart failure. (2 marks) [1]

SAQ 2 (10 marks)

A five-day-old term infant is brought to the emergency department pale, grunting and tachypnoeic. She has been feeding poorly for a day. On examination she is centrally cyanotic with an oxygen saturation of 78 per cent in air that rises only to 84 per cent on high-flow oxygen, a respiratory rate of 70, weak femoral pulses with brachial pulses that feel stronger, a blood pressure of 70/40 in the right arm and 50/30 in the legs, and a soft, barely audible systolic murmur at the left sternal edge. The liver is palpable three centimetres below the costal margin. [2] [11]

a) Give the working diagnosis, name the bedside finding that points to coarctation of the aorta, and explain why the murmur is soft rather than loud. (3 marks) [2] [8]

b) Outline the immediate resuscitation, naming the drug, the dose range, its mechanism, and its common adverse effects. (3 marks) [2] [11]

c) Describe how you would distinguish a cyanotic cardiac lesion from a pulmonary cause of neonatal cyanosis, and interpret the differential cyanosis finding (a higher saturation in the right hand than in the foot). (2 marks) [2]

d) Contrast this presentation with a hypercyanotic (tet) spell in a six-month-old with tetralogy of Fallot, describing the clinical features, why squatting helps, and the spell bundle. (2 marks) [9] [12]

Marking guide

SAQ 1. The murmur is a soft, short, vibratory systolic murmur of grade two at the lower left sternal edge that softens on sitting forward — a textbook Still's murmur. It is innocent, because it fits the benign fingerprint completely: soft and short, systolic, grade two or less, at the left sternal edge, with normal first and second heart sounds (a normally split second sound rules out an atrial septal defect and pulmonary stenosis), no thrill, no radiation, and an asymptomatic thriving child with normal pulses, a normal four-limb blood pressure (no arm-to-leg gap) and a normal pre- and post-ductal saturation. [1] [4]

The systematic examination is the fixed sequence: inspect (colour, work of breathing, precordium, syndromic features, clubbing); palpate (the apex for site and character, the right ventricle for a heave, any thrill, and the femoral and brachial pulses together); auscultate the five areas — aortic (right upper sternal edge), pulmonary (left upper sternal edge), Erb's point (left sternal edge), tricuspid (lower left sternal edge) and mitral (apex) — with the diaphragm for high-pitched sounds and the bell for low-pitched sounds, listening to the heart sounds before the murmur. The two measurements that must never be omitted are the four-limb blood pressure (to catch coarctation) and the pre- and post-ductal oxygen saturation (to catch the ductal right-to-left shunt). [1] [4]

The diagnosis is an innocent (Still's) murmur. No further investigation is needed: the fingerprint is complete and the pulses, blood pressure and saturation are normal, so an echocardiogram is not indicated and would almost certainly be normal. The family is told that a murmur is a sound and not a disease, that the heart is structurally normal, and that the child can do everything a child without a murmur can do. The safety-net is to return urgently with cyanosis, poor feeding, breathlessness, sweating with feeds or poor growth. [1]

A pansystolic murmur at the lower left sternal edge in a six-week-old is a ventricular septal defect. The features that suggest a large defect and evolving heart failure are a loud harsh murmur with a thrill, bounding pulses and a wide pulse pressure from the large shunt, tachypnoea, sweating with feeds, hepatomegaly and failure to thrive as the pulmonary vascular resistance falls over the first weeks and the left-to-right shunt grows. [1]

SAQ 2. The working diagnosis is a duct-dependent critical congenital heart lesion, with the weak femoral pulses, the stronger brachial pulses and the arm-to-leg systolic blood pressure gap (70/40 against 50/30) pointing specifically to coarctation of the aorta or an interrupted arch. The murmur is soft rather than loud because the obstruction is so severe that little blood crosses it to generate turbulence, and the duct carries the flow instead — the critical-stenosis paradox and the reason the sickest duct-dependent neonates are the quietest. [2] [8]

The immediate resuscitation is prostaglandin E1 (alprostadil) at 0.01 to 0.05 micrograms per kilogram per minute to reopen or maintain the arterial duct. Its mechanism is relaxation of the ductal smooth muscle, restoring the ductal flow that the obstructed left heart cannot provide. The common adverse effects are apnoea, hypotension, fever and irritability, so the infant is monitored in a neonatal or paediatric intensive care setting and intubated early if apnoea develops; the fever can be mistaken for sepsis. Oxygen, intravenous access, correction of the metabolic acidosis and the glucose, and transfer to a paediatric cardiology centre complete the resuscitation. [2] [11]

A cyanotic cardiac lesion is distinguished from a pulmonary cause by a saturation that does not rise on one hundred per cent oxygen (the hyperoxia test) alongside a normal or near-normal chest X-ray, and by the weak pulses, the arm-to-leg blood pressure gap and the hepatomegaly. A differential cyanosis — a higher saturation in the right hand than in the foot — localises the right-to-left shunt to the duct, as in coarctation or an interrupted arch with ductal right-to-left flow. [2]

A hypercyanotic (tet) spell in a six-month-old with tetralogy of Fallot presents as a sudden deepening of cyanosis with inconsolable crying, tachypnoea and irritability, often triggered by crying, fever or exertion. Squatting (or the knee-to-chest position) raises the systemic vascular resistance, reduces the right-to-left shunt and increases pulmonary blood flow, which is why the child self-corrects. The spell bundle is knee-to-chest, high-flow oxygen, an intravenous fluid bolus, morphine around 0.1 mg/kg, phenylephrine to raise the systemic vascular resistance, a beta-blocker to relax the infundibular spasm, and prostaglandin E1, anaesthesia or surgery if refractory. [9] [12]