Computed tomography in the evaluation for transcatheter aortic valve implantation (TAVI)

Abstract

If left untreated, symptomatic, severe aortic stenosis (AS) is associated with a dismal prognosis. Open-heart surgical valve replacement is the treatment of choice and is associated with excellent short and long-term outcome. However, many older patients with multiple co-morbidities and anticipated increased surgical risk are excluded from surgical intervention. For these patients, transcatheter aortic valve implantation (TAVI) is emerging as a viable treatment alternative. Transcatheter valvular heart procedures are characterized by lack of exposure and visualization of the operative field, therefore relying on image guidance, both for patient selection and preparation and the implantation procedure itself. This article describes the role of multi-detector row computed tomography (MDCT) for detailed assessment of the aortic valve, aortic root, and iliac arteries in the context of TAVI.

Keywords: Aortic stenosis; computed tomography; imaging; transcatheter aortic valve implantation.

Figures

Figure 1

Valvular and LV function: retrospective gated image acquisition allows 4-D image reconstruction of multiple adjacent reconstructions along the cardiac cycle displayed as cine-loops for evaluation of valvular and LV ventricular function. This figure shows images of LV analysis (left panel) and images focused on the mitral valve

Movie 1

Retrospective gated image acquisition allows 4-D image reconstruction of multiple adjacent reconstructions along the cardiac cycle displayed as cine-loops for evaluation of valvular function. This movie shows the star-shaped opening of a tricuspid valve

Movie 2

In contrast to Movie 1, this movie shows an example of a bicuspid valve with fusion of the non- and right coronary cusp and eccentric, slit-like opening

Figure 2

Annulus Measurements: this figure demonstrates measurements at the annulus. For imaging, the annulus is defined at the level immediately below the lowest insertion point of the aortic leaflets. Measurements are taken from the phase with maximum valve opening. In this plane minimal, maximal, and mean diameter are described, with the mean diameter having the best correlation with echocardiography

Figure 3

Coronary Ostia: CT allows to assess the relationship between leaflet height and distance between annulus and coronary ostia, which identifies patients at risk for coronary occlusion during the TAVI procedure. This figure demonstrated measurements of the distance between the annulus and ostia of the left main (LM) and right coronary artery (RCA)

Movie 3

Coronary ostia and relationship to valve leaflets: CT allows to assess the relationship between leaflet height and distance between annulus and coronary ostia, which identifies patients at risk for coronary occlusion during the TAVI procedure. The movie files demonstrate cine-loops reconstructed at multiple phases of the cardiac cycle. This movie shows the relationship between the coronary ostia and the valve leaflets

Figure 4

Aortic Valve Area: detailed analysis of data in reconstructions along the cardiac cycle allows to identify the systolic phase with maximum valve opening (typically 20-30% RR-interval). In this reconstruction, a plane perpendicular to the valve plane is placed at the leaflet tips to measures the aortic valve opening area (AVA) by planimetry. This figure shows the star-shaped opening of a tricuspid valve

Figure 5

Bicuspid Aortic Valve: in contrast to Figure 4, this figure shows an example of a bicuspid valve with fusion of the non- and right coronary cusp and eccentric, slit-like opening. A systolic (left panel) and diastolic (right panel) reconstruction is shown

Figure 6

Aortic Valve Commisure Calcification: while CT is limited by blooming artifact from dense calcification, CT allows quantification and precise localization of calcification. The relationship between the calcification and postprocedural aortic regurgitation are unclear

Figure 7

Mitral Annular Calcification: CT allows precise localization of mitral annular calcification. The impact of mitral annular calcification remains unclear

Figure 8

Root Angulation: for the description of the aortic valve plane, double oblique transverse multiplanar reconstructions at the level of the aortic root are performed and rotated through a series of any angles. The right hand images show images perpendicular to the valve plane corresponding to angiographic images

Figure 9

Iliac Arteries: at least 1/3 of patients with critical aortic stenosis have unfavorable iliofemoral arteries. Centerline image processing of the iliac arteries (left panels) and cross-sectional images at the different levels allow assessment of dimensions, calcification, and angulation (right)