Evaluation of advancing the standard valve dysfunction by multidetector-row CT

Cardiac Computed Tomography for Structural Heart Disease Assessment and Therapeutic Planning: Focus on Prosthetic Valve Dysfunction

Of the 100,000-plus valve surgeries performed each year in the United States, up to 6% of those develop complications from prosthetic valve dysfunction. Prosthetic valve dysfunction (PVD) can be life threatening and often challenging to diagnose. In this review, we discuss the prevalence and incidence of PVD, explore its different etiologies, and assess the role of multimodality imaging with an emphasis on cardiac multidetector computed tomography (MDCT) for evaluating patients with PVD. We also investigate the utility of MDCT in preprocedural planning for transcatheter devices and redo surgical planning and discuss management strategies for patients with PVD.

Effects of pannus formation on the flow around a bileaflet mechanical heart valve

Some patients with a bileaflet mechanical heart valve (BMHV) show significant increases in the transvalvular pressure drop and abnormal leaflet motion due to a pannus (an abnormal fibrovascular tissue) formed on the ventricular side, even in the absence of physical contact between the pannus and leaflets. We investigate the effects of the pannus shape (circular or semi-circular ring), implantation location and height on the leaflet motion, flow structure and transvalvular pressure drop using numerical simulations. The valve model considered resembles a 25 mm masters HP valve. The mean systolic pressure drop is significantly increased with increasing pannus height, irrespective of its implantation orientation. Near the peak inflow rate, the flow behind the pannus becomes highly turbulent, and the transvalvular pressure drop is markedly increased by the pannus. At the end of valve opening and the start of valve closing, oscillatory motions of the leaflets occur due to periodic shedding of vortex rings behind the pannus, and their amplitudes become large with increasing pannus height. When the pannus shape is asymmetric (e.g., a semi-circular ring) and its height reaches about 0.1D (D (= 25 mm) is the diameter of an aorta), abnormal leaflet motions occur: two leaflets move asymmetrically, and valve closing is delayed in time or incomplete, which increases the regurgitation volume. The peak energy loss coefficients due to panni are obtained from simulation data and compared with those predicted by a one-dimensional model. The comparison indicates that the one-dimensional model is applicable for the BMHV with and without pannus.

Value of Computed Tomography Radiomic Features for Differentiation of Periprosthetic Mass in Patients With Suspected Prosthetic Valve Obstruction

Background:

We aimed to determine whether quantitative computed tomography radiomic features can aid in differentiating between the causes of prosthetic valve obstruction (PVO) in patients who had undergone prosthetic valve replacement.

Methods:

This retrospective study included 39 periprosthetic masses in 34 patients who underwent cardiac computed tomography scan from January 2014 to August 2017 and were clinically suspected as PVO. The cause of PVO was assessed by redo-surgery and follow-up imaging as standard reference, and classified as pannus, thrombus, or vegetation. Visual analysis was performed to assess the possible cause of PVO on axial and valve-dedicated views. Computed tomography radiomic analysis of periprosthetic masses was performed and radiomic features were extracted. The advantage of radiomic score compared with visual analysis for differentiation of pannus from other abnormalities was assessed.

Results:

Of 39 masses, there were 20 cases of pannus, 11 of thrombus, and 8 of vegetation on final diagnosis. The radiomic score was significantly higher in the pannus group compared with nonpannus group (mean, −0.156±0.422 versus −0.883±0.474; P <0.001). The area under the curve of radiomic score for diagnosis of pannus was 0.876 (95% CI, 0.731–0.960). Combination of radiomic score and visual analysis showed a better performance for the differentiation of pannus than visual analysis alone.

Conclusions:

Compared with visual analysis, computed tomography radiomic features may have added value for differentiating pannus from thrombus or vegetation in patients with suspected PVO.

Use of multidetector-row computed tomography scan to detect pannus formation in prosthetic mechanical aortic valves

Obstruction of a mechanical aortic valve by pannus formation at the subvalvular level is a major long-term complication of aortic valve replacement (AVR). In fact, pannus is sometime difficult to differentiate from patient-prosthesis mismatch or valve thrombosis. In most cases cine-angiography and echocardiography, either transthoracic or transesophageal, cannot correctly visualize the complication when the leaflets show a normal mobility. Recent technological refinements made this difficult diagnosis possible by ECG-gated computed tomography (CT) scan which shows adequate images in 90% of the cases and can differentiate pannus from fresh and organized thrombus.

Multimodality Imaging Assessment of Prosthetic Heart Valves

Echocardiography and fluoroscopy are the main techniques for prosthetic heart valve (PHV) evaluation, but because of specific limitations they may not identify the morphological substrate or the extent of PHV pathology. Cardiac computed tomography (CT) and magnetic resonance imaging (MRI) have emerged as new potential imaging modalities for valve prostheses. We present an overview of the possibilities and pitfalls of CT and MRI for PHV assessment based on a systematic literature review of all experimental and patient studies. For this, a comprehensive systematic search was performed in PubMed and Embase on March 24, 2015, containing CT/MRI and PHV synonyms. Our final selection yielded 82 articles on surgical valves. CT allowed adequate assessment of most modern PHVs and complemented echocardiography in detecting the obstruction cause (pannus or thrombus), bioprosthesis calcifications, and endocarditis extent (valve dehiscence and pseudoaneurysms). No clear advantage over echocardiography was found for the detection of vegetations or periprosthetic regurgitation. Whereas MRI metal artifacts may preclude direct prosthesis analysis, MRI provided information on PHV-related flow patterns and velocities. MRI demonstrated abnormal asymmetrical flow patterns in PHV obstruction and allowed prosthetic regurgitation assessment. Hence, CT shows great clinical relevance as a complementary imaging tool for the diagnostic work-up of patients with suspected PHV obstruction and endocarditis. MRI shows potential for functional PHV assessment although more studies are required to provide diagnostic reference values to allow discrimination of normal from pathological conditions.

A reoperation of thrombosed On-X valve detected by multidetector-row computed tomography

A 62-year-old female patient underwent mitral valve replacement with a 31/33-mm On-X valve for ischemic mitral valve regurgitation. Three months later, transthoracic echocardiography incidentally showed a blocked leaflet with 6 mmHg of mean pressure gradient and 2.4 cm(2) of mitral valve orifice area. Transesophageal echocardiography could not detect thrombus. Electrocardiographically gated multidetector-row computed tomography (MDCT) clearly demonstrated a blocked leaflet in the close position and thrombus (2 cm in length, 0.4 cm(2) in area) attached onto the atrial aspect of the leaflet. These findings observed by MDCT were confirmed at reoperation. MDCT was useful diagnostic method for visualizing prosthetic valve thrombosis.