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Physiology · Cardiovascular system: Eisenmenger syndrome
Sample itemA 25-year-old woman with an untreated large ventricular septal defect since childhood now has cyanosis and clubbing, and the murmur has become soft. Which haemodynamic change explains the cyanosis?
Original practice item, not a recalled exam question. Nothing here is recorded.
The answer and the reasoning
B. Pulmonary vascular resistance exceeding systemic resistance, reversing the shunt
Years of left-to-right flow damage the pulmonary vessels and raise resistance. Once pulmonary pressure exceeds systemic pressure the shunt reverses to right-to-left, which causes central cyanosis and softening of the murmur.
Option by option
A. Obstruction to right ventricular outflow
RV outflow obstruction describes Fallot tetralogy, a separate lesion.
B. Pulmonary vascular resistance exceeding systemic resistance, reversing the shunt (correct)
Correct. Reversal of the shunt from raised pulmonary resistance causes cyanosis.
C. Loss of the septal defect
The defect persists; it is the direction of flow that changes.
D. Increased left-to-right flow with pulmonary oedema
A left-to-right shunt does not cause cyanosis.
Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.
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