Interpret a paediatric echocardiogram report — OSCE

Candidate brief

You have this station to interpret the paediatric echocardiogram report of a six-year-old boy with a bicuspid aortic valve, apply the systematic read, calculate the valve gradient, interpret the Z-scores, give the differential and the disposition, and outline the prostaglandin resuscitation of a duct-dependent neonate. Treat this as a calm clinic consultation, with an explicit systematic read and a defensible plan. [1] [9]

Key teaching and management objectives

Begin with the systematic read of the report in the order structure, function, valves, flow, pericardium, and special findings. The structure shows a bicuspid aortic valve with otherwise normal connections; the function is normal, with a fractional shortening of 34 percent (within the normal range of about 28 to 44 percent); the left ventricular Z-score of 0.8 is normal, confirming the ventricle is neither dilated nor hypertrophied; the aortic root is normal. The critical calculation is the valve gradient from the peak velocity by the modified Bernoulli equation. [1] [7]

State the modified Bernoulli equation: the peak pressure gradient, in millimetres of mercury, is approximately four times the square of the peak velocity in metres per second. At a peak velocity of 4 metres per second, the gradient is four times 16, which is 64 millimetres of mercury, and a gradient of this magnitude defines severe aortic stenosis. Explain that Doppler measures a velocity, not a pressure, and the equation is the bridge between them, with the assumption that the proximal velocity is negligible. [12]

Give the differential of a bicuspid aortic valve with a high gradient: the gradient reflects the fixed obstruction at the valve, and the surveillance must track the progression of the stenosis, the left ventricular hypertrophy and function, and the aortic root, because bicuspid valves are associated with aortopathy and progressive root dilation. [9]

Close with the disposition: routine paediatric cardiology referral and serial echocardiographic surveillance at intervals guided by the appropriate-use criteria, with the threshold for balloon valvuloplasty or surgical intervention set by the gradient, the ventricular function, and the symptoms. Then, if asked, outline the prostaglandin resuscitation of a duct-dependent neonate: a child who collapses as the ductus closes on day three of life has a duct-dependent lesion until the echo proves otherwise, and the first dose of intravenous prostaglandin E1 at 0.005 to 0.01 micrograms per kilogram per minute, titrated up to 0.05 to 0.1, must not wait for the cardiologist. [9] [12]

Marking domains

• Systematic age- and size-referenced read (4 marks). Names the five-step sequence (structure, function, valves, flow, pericardium); interprets the fractional shortening of 34 percent as normal; correctly reads the Z-score of 0.8 as normal.
• Modified Bernoulli equation and gradient (3 marks). States the equation (four times velocity squared); calculates the gradient of 64 millimetres of mercury; identifies this as severe aortic stenosis.
• Differential and surveillance (3 marks). Names the bicuspid valve lesion, the need to track the gradient, the ventricular hypertrophy and function, and the aortic root for aortopathy.
• Disposition and safety advice (3 marks). Routine cardiology referral and serial surveillance; threshold for intervention set by gradient, function, and symptoms; advice on activity and follow-up.
• Prostaglandin resuscitation of the duct-dependent neonate (2 marks). Names prostaglandin E1 intravenously at 0.005 to 0.01 micrograms per kilogram per minute titrated up to 0.05 to 0.1; states it must not wait for the cardiologist. [9] [1]