Cardiovascular examination and murmur assessment — branching viva

Opening framework

My framework has three layers. First, the recognition — a heart murmur is audible turbulent flow, and the task at the bedside is to decide whether it fits the innocent fingerprint or departs from it. Second, the examination — a fixed sequence of inspect, palpate, auscultate, completed by a four-limb blood pressure and a pre- and post-ductal saturation, because these two measurements catch the lesions the stethoscope misses. Third, the disposition — reassurance for the complete innocent fingerprint, referral and echocardiography for any departure, and prostaglandin E1 for the suspected duct-dependent neonate before the echo confirms the lesion. [1]

The well child with an incidental murmur

This murmur is an innocent Still's murmur. It is soft, short, vibratory and systolic, grade two at the lower left sternal edge, and it softens when the child sits forward. It fits the benign fingerprint completely: normal first and second heart sounds with a normally split second sound (ruling 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 and a normal pre- and post-ductal saturation. The Still's murmur is the commonest innocent murmur of early childhood, a low-frequency musical sound produced by normal flow in a normal heart. [1] [4]

The systematic examination and the two non-negotiable measurements

The examination is a fixed sequence. Inspect the colour, the work of breathing, the precordium, the fingers for clubbing and the face for syndromic features. Palpate the apex for site and character, the right ventricle for a heave, any thrill over the precordium, and the femoral and the 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 any murmur. The two measurements that must never be omitted are the four-limb blood pressure (an arm-to-leg systolic gap above twenty millimetres of mercury is coarctation until proven otherwise) and the pre- and post-ductal saturation (a post-ductal saturation below ninety-five per cent or a hand-to-foot gap above three per cent warrants assessment for congenital heart disease). [1] [4]

Branch: the five-day-old cyanotic infant with weak femoral pulses

For the five-day-old cyanotic infant with weak femoral pulses and an arm-to-leg blood pressure gap, the diagnosis is a duct-dependent critical congenital heart lesion, with the findings pointing to coarctation of the aorta or an interrupted arch. The lesion is survivable in utero because the arterial duct carries the blood the obstructed left heart cannot route, and the infant collapses as the duct closes over the first days to weeks. The murmur is soft because little blood crosses the severe obstruction to generate turbulence — the critical-stenosis paradox. [2] [8]

The resuscitation is prostaglandin E1 (alprostadil) at 0.01 to 0.05 micrograms per kilogram per minute, which relaxes the ductal smooth muscle and reopens or maintains the duct. It is started before the echocardiogram confirms the anatomy, because the child recovers when the duct reopens and collapses when it closes. 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]

Closing: the six-month-old who squats and turns cyanotic

The closing branch — a six-month-old with tetralogy of Fallot who suddenly squats and turns deeply cyanotic — is a hypercyanotic (tet) spell. Anything that lowers the systemic vascular resistance, such as crying or exertion, shunts more desaturated blood right-to-left across the ventricular septal defect, and the child becomes deeply cyanotic. 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 and why the knee-to-chest position is the first move in the bundle. [9] [12]

The spell bundle is knee-to-chest, high-flow oxygen, an intravenous fluid bolus to raise the preload, morphine around 0.1 mg/kg to calm the child and reduce the sympathetic tone that drives the infundibular spasm, phenylephrine to raise the systemic vascular resistance, a beta-blocker such as propranolol or esmolol to relax the infundibular spasm, and prostaglandin E1, anaesthesia or surgery if refractory. The bundle is given together, not in sequence, and the child is admitted to a paediatric intensive care setting with the cardiology team involved. The longer lesson is the disposition: every child with a murmur leaves with a clear written plan naming the diagnosis, the red flags, the safety-net and the follow-up. [12] [9]