What is the clinical evidence from this study?

Study design: Observational. Population: Prosthetic valve obstruction (n=9). Intervention: Multidetector-row computed tomography (MDCT) vs. Interventricular septum (internal control for CT attenuation). Primary outcome: Mean CT attenuation (Hounsfield units) (p=<0.0001).

October 31, 2012Open Access

Evaluation of Prosthetic Valve Obstruction on Electrocardiographically Gated Multidetector-Row Computed Tomography

Q: What are the key findings of this study?

MDCT clearly visualized subprosthetic pannus causing prosthetic valve obstruction, with the mean CT attenuation of pannus (170 HU) being significantly higher than that of the interventricular septum (108 HU, P<0.0001).

Key Result

MDCT clearly visualized subprosthetic pannus causing prosthetic valve obstruction, with the mean CT attenuation of pannus (170 HU) being significantly higher than that of the interventricular septum (108 HU, P<0.0001).

Study Design

Type

Observational (n=9)

Multicenter

Structured PICO

Does electrocardiographically gated MDCT accurately visualize and characterize the cause of prosthetic valve obstruction in patients with aortic bileaflet mechanical valves?

Population

9 patients (mean age 65.4 years, 78% female) with prosthetic valve obstruction of an aortic mechanical valve who underwent MDCT prior to reoperation.

Exposure

Electrocardiographically gated multidetector-row computed tomography (MDCT)

Comparator

Intraoperative findings (reference standard)

Outcome

Morphologic periprosthetic abnormalities and CT attenuation (Hounsfield units) of the underlying cause of PVOsurrogate

ECG-gated MDCT can effectively visualize subprosthetic pannus causing aortic prosthetic valve obstruction and characterize it using CT attenuation.

Main Result

Absolute Event Rate: 170% vs 108%

p-value: p=<0.0001

Limitations

Small number of patients with prosthetic valve obstruction (only 9 patients).
Few data available on MDCT appearance in a normally functioning prosthetic valve without obstruction.
MDCT was not available for the other 21 patients who received replacement of the aortic prosthetic valve for obstruction before 2002.

Abstract

BACKGROUND: This study was performed to evaluate the diagnostic role of electrocardiographically gated multidetector-row computed tomography (MDCT) for prosthetic valve obstruction (PVO) in the aortic position. METHODS AND RESULTS: Between 2002 and 2006, 9 patients were diagnosed with PVO of an aortic bileaflet mechanical valve based on echocardiographic and cineradiographic criteria. These 9 patients were examined using MDCT before replacement of the mechanical valve, and intraoperative findings were compared to morphologic periprosthetic abnormalities observed on MDCT. CT attenuation (Hounsfield units; HU) of the periprosthetic abnormalities was measured to investigate the underlying cause of the PVO. MDCT showed subprosthetic masses extending beyond the prosthetic ring into the orifice of the valve. At reoperation, presence of subprosthetic pannus was confirmed in all of the 9 patients, but no periprosthetic thrombus was found. The mean CT attenuation of the subprosthetic pannus was 170 HU, and it was significantly greater than that obtained from the interventricular septum (108 HU; P<0.0001). CONCLUSIONS: MDCT can be used to clearly visualize subprosthetic pannus causing PVO and the mean CT attenuation of subprosthetic pannus is significantly higher than that of the interventricular septum on MDCT.

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