Answer: C. Right atrial pressure >10 mm Hg

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Figure 1

(A) Pulsed-wave Doppler tracing of transpulmonic flow. (B) Continuous-wave Doppler tracing of transtricuspid flow.

Figure 1A demonstrates significant pulmonary regurgitation into a restrictive right ventricle (RV). During early diastole, regurgitation from the pulmonary artery (PA) into the RV is present. In late diastole, antegrade flow from the RV into the PA is present, a finding seen in restrictive RV filling. In the setting of restrictive physiology, atrial contraction in late diastole forces blood into a poorly compliant RV resulting in premature opening of the pulmonic valve with antegrade flow on spectral and colour Doppler.1 2 Restrictive RV physiology is common in patients with congenital RV outflow tract obstruction, seen in conditions such as Tetralogy of Fallot and pulmonary atresia, sometimes even after timely repair.3 Delayed repair of the obstruction may result in myocardial fibrosis and restrictive physiology, which is associated with poor clinical outcomes in some, but not all, studies.4 High right atrial pressures would be expected in the presence of a non-compliant RV, therefore, answer C is correct. There is no flow from the LVOT to RVOT in figure 1A to suggest a supracristal VSD, so answer A is incorrect. Figure 1B shows the transtricuspid pressure gradient to be 19 mm Hg, inconsistent with pulmonary hypertension, so B and D are incorrect. Near equalisation of diastolic PA pressures and RV end-diastolic pressures is expected in the setting of severe pulmonary regurgitation. Since RV end-diastolic pressures are likely to be high given RV restriction, answer E is incorrect.