Usefulness of ECG-gated multi-detector computed tomography for the diagnosis of mechanical prosthetic valve dysfunction

A 70-year-old woman who had an aortic valve replacement with a bileaflet mechanical prosthetic aortic valve 14 months earlier, presented with congestive heart failure. She was operated for intestinal carcinoma that resulted in an inadequate anticoagulation management. On presentation, the international normalized ratio was 1.9. Initial examination revealed a loud systolic aortic murmur and muffling of the valve click. Echocardiography coupled with Doppler showed an increased valvular mean pressure gradient (Panel A) as compared with the previous values (45 vs. 18 mmHg) associated with a grade I aortic regurgitation. As the patient was haemodynamically unstable, a transoesophageal echocardiography could not be performed. To clarify the mechanism of the valve dysfunction, a 16-slice spiral computed tomography (CT) with three-dimensional volume rendering reconstruction centered on the aortic prosthetic valve was performed (scan parameters: rotation time, 0.5 s; slice thickness, 0.625 mm; increment reconstruction, 0.5 mm; retrospective reconstruction of 20 phases of the R–R interval). On these views, one hemidisk was totally immobile and stayed open during diastole (white arrow) (Panel B: lateral view, Panel C: upper view).