Reduced leaflet motion refers to an abnormally decreased mobility of one or more valvular leaflets and is a phenomenon that has been observed after (transcatheter) implantation of prosthetic heart valves and gained clinical significance for the diagnosis of subclinical leaflet thrombosis.
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Epidemiology
Reduced leaflet motion has been observed in up to 13% of transcatheter aortic valve implantations (TAVI) and up to 4% of patients with surgical aortic valve replacements (SAVR) 1,2.
Associations
Reduced leaflet motion is associated with hypoattenuated leaflet thickening and (subclinical) leaflet thrombosis.
Radiographic features
Echocardiography
Transthoracic echocardiography is used for the evaluation of regurgitation and/or stenosis, but its role in the assessment of reduced leaflet motion is limited 3. In the setting of inconclusive results and/or abnormal transvalvular gradients transesophageal echocardiography might be considered 3-7.
CT
Cardiac CT for the evaluation of heart valves should be acquired with retrospective acquisition and no dose modulation 4. A high spatial and temporal resolution is required 4. Reduced leaflet motion can be assessed by multiphasic CT acquisition of the affected valve leaflet with the evaluation of the phase with the maximal leaflet excursion for the aortic valve during systole. It can be depicted on 4D volume rendering and calculated as follows 4:
- reduced leaflet motion [%] = affected leaflet width / frame radius x 100%
Reduced leaflet motion can be then classified as follows 4,5:
- mild <50%
- moderate 50-70%
- severe >70%
- immobile no motion
A moderately reduced leaflet motion (>50%) is considered significant.
Practical points
Leaflet motion can be evaluated on cardiac CT in the setting of hypoattenuated leaflet thickening and suspected leaflet thrombosis after leaflet coaptation has been established 4,5. If leaflet coaptation cannot be seen or findings are inconclusive transesophageal echocardiography should be considered for further evaluation 3,4.
The association of reduced leaflet motion with hypoattenuated leaflet thickening allows the diagnosis of subclinical leaflet thrombosis especially also in the setting of elevated transvalvular gradients 6.
Depending on the density of the prosthetic valve it might be considered to increase tube voltage to 140 kV 4.