Role of computed tomography imaging for transcatheter valvular repair/insertion

Abstract

During the last decade, the development of transcatheter based therapies has provided feasible therapeutic options for patients with symptomatic severe valvular heart disease who are deemed inoperable. The promising results of many nonrandomized series and recent landmark trials have increased the number of percutaneous transcatheter valve procedures in high operative risk patients. Pre-procedural imaging of the anatomy of the aortic or mitral valve and their spatial relationships is crucial to select the most appropriate device or prosthesis and to plan the percutaneous procedure. Multidetector row computed tomography provides 3-dimensional volumetric data sets allowing unlimited plane reconstructions and plays an important role in pre-procedural screening and procedural planning. This review will describe the evolving role of multidetector row computed tomography in patient selection and strategy planning of transcatheter aortic and mitral valve procedures.

Figures

Fig. 1

Aortic valve calcification assessed using multidetector row computed tomography (MDCT): implications for transcatheter aortic valve implantation. a shows a calcified tricuspid aortic valve with bulky calcification mainly in the left cusp, left–right commissure and extending to the base of the anterior mitral valve leaflet (indicated by arrows in b). Following TAVI, paravalvular leak was observed with colour Doppler transesophageal echocardiography in the long-axis view (c) that coincided with the location of bulky calcification at the left–right commissure on MDCT (in a). In this example, the bulky calcified cusp and commissure might pose resistance during transcatheter prosthesis deployment, resulting in subsequent paravalvular leak (arising from the gap between the prosthesis and native valve). LA left atrium, RV right ventricle

Fig. 2

Aortic valve annular dimensions. Multidetector row computed tomography (MDCT) permits excellent visualization of the oval-shaped aortic annulus with correct alignment of the orthogonal multiplane reformation planes (a and b). The correct aortic annular plane is defined at the lowest attachment point of all the three valve leaflets (c) and multiple measurements of the aortic annulus can be made: minimum (Dmin), maximum (Dmax), mean (Dmean = [Dmin + Dmax]/2) diameters and cross-sectional areas (CSA)

Fig. 3

Assessment of the height of the coronary ostia relative to the aortic annular plane. Multidetector row computed tomography (MDCT) permits accurate orientation of the aortic annular plane (a) and precise measurement of the distance between the left and right coronary ostia and the annular plane (b and c). In addition, the length of the valvular leaflet, measured from the aortic annulus to the cusp tip, can be obtained on MDCT (red arrow in b)

Fig. 4

Evaluation of peripheral arteries with multidetector row computed tomography (MDCT). a shows an example of infrarenal aorta, iliac and femoral arteries in a 3-dimensional volume rendering view. Using the center-line approach, the curved multiplanar reformation (MPR) permits reconstruction of the curved planes, following the course of the vessels. Subsequently, the true cross-sectional internal diameter and area of the iliac artery can be measured from the double oblique transverse view in (c and d). With the current MDCT post-processing imaging software (3mensio Valves™, version 4.2., 3mensio Medical Imaging BV, Bilthoven, The Netherlands), the minimum diameter threshold required for the currently available transfemoral devices is 6 mm (18 Fr) and this minimum requirement is simultaneously displayed side-by-side in the curved MPR views (b). Therefore, the presence of a minimal luminal diameter of the iliofemoral arteries <6 mm does not favor the transfemoral approach. In contrast, the example in d shows a vessel with a minimal luminal diameter >6 mm, as indicated by the dotted green circle which is larger than the size of a simulated 18 Fr sheath (in solid red circle). In addition, the 3-dimensional reconstruction volume rendering technique of MDCT allows rotations and displays the tortuous course of the iliofemoral arteries. e gives the precise measurement of one of the angulations seen in the left external iliac artery (51°), rendering it unsuitable for the transfemoral approach

Fig. 5

Planning of angiographic planes. Using reformation reconstruction of multidetector row computed tomography (MDCT), the appropriate aortic valve plane for transcatheter aortic valve implantation can be anticipated (a). The ideal angiographic projection should be one that aligns all the three aortic cusps in a straight line, perpendicular to the aortic valve plane (b). LCC left coronary cusp, NCC non-coronary cusp, RCC right coronary cusp

Fig. 6

Assessment of the left ventricular geometry may be of relevance in the planning of the transapical approach. The relation of the left ventricular apex and the aortic annulus valve plane (the so called “ventriculo-aortic angle”) can be reliably measured on multidetector row computed tomography (MDCT). Insert a shows the direction of a simulated delivery system through the left ventricular apex, towards the aortic valve. In addition, the thickness of the left ventricular septum wall can be measured on MDCT (arrow in insert b). Post-processing imaging software (3mensio Valves™, version 4.2., 3mensio Medical Imaging BV, Bilthoven, The Netherlands)

Fig. 7

Evaluation of underlying mechanism of mitral regurgitation with multidetector row computed tomography (MDCT). Mitral valve prolapse can be identified accurately with MDCT. a shows an example of a patient with prolapse of the posterior leaflet (arrow). Color Doppler echocardiography permits quantification of the regurgitant volume and the direction of the regurgitant jet (b). Modified with permission from Feutchner et al. [44]

Fig. 8

Mitral valve geometry assessment with multidetector row computed tomography (MDCT) in functional mitral regurgitation. From the short-axis view of the mitral valve at the level of the mitral leaflets and commissures, the orthogonal planes across the anterolateral (A1–P1), central (A2–P2) and posteromedial (A3–P3) provide the apical views of the mitral valve apparatus and permits the measurement of the leaflet angles and tenting heights (arrows)

Fig. 9

Multidetector row computed tomography (MDCT) prior to coronary sinus-based mitral valve annuloplasty. Combination of 3-dimensional volume rendering and axial views of the mitral valve annulus permit assessment of the key anatomic relationships of the coronary sinus: its position relative to the mitral annular plane and the circumflex coronary artery. a shows an example of a patient with the coronary sinus properly aligned with the mitral annulus (as seen with the 3-dimensional volume rendering). However, at the level of the distal part of the coronary sinus, where the distal anchor is positioned, the circumflex coronary artery courses between the mitral annulus and the coronary sinus. The risk of coronary impingement in this example may contraindicate the procedure. In contrast, b shows an example where the coronary sinus courses superiorly to the posterior mitral annulus. The coronary sinus-based mitral annuloplasty may be less effective in this case, since the tension is applied to the posterior wall of the left atrium rather than the mitral annulus. In addition, there is a potential risk of circumflex coronary artery compromise as the distal part of the coronary sinus courses over the artery (arrow). CS coronary sinus, CX left circumflex artery