CT Imaging for Valvular Interventions

Abstract

Physician-led computed tomography (CT) imaging for valvular interventions has directly contributed to the safety and scalability of transcatheter aortic valve interventions globally. As the shift of the global population's valvular heart disease extends into the transcatheter aortic, mitral, pulmonic, and tricuspid space, CT imaging for valvular interventions in new anatomical pathophysiologies becomes more important than ever. Health systems dedicated to investing in physician-led structural heart imaging CT procedural planning expertise and transcatheter treatment advancements can bring life-saving innovative care to patients in need.

Keywords: 3D; CT; Mitral; TAVR; Transcatheter; Tricuspid.

Figure 1

Artifact seen due to poor bolus tracking by scanner. Improper region of interest (ROI) placement at the level of the pulmonary veins, highlighted in red dotted circles on the baseline scan setup seen in panel (a) results in poorly enhanced CT images at the level of the left atrial appendage (LAA) in panel (c). Repeat CT scan with the ROI correctly placed within the center of the left atrium, green dotted circle as depicted in panel (b), results in optimal contrast opacification of the left heart and LAA as seen in panel (d). Figure adapted from Kaafarani M, Wang DD et al. “Role of CT Imaging in left atrial appendage occlusion for the WATCHMAN device.” 2019 https://doi.org/10.21037/cdt.2019.12.01. Abbreviation: CT, computed tomography; HU, Hounsfield unit; LA, left atrium; LV, left ventricle; RA, right atrium; RV, right ventricle; SVC, superior vena cava.

Figure 2

Impact of challenging body habitus anatomy on wire selection. Anterior-posterior and sagittal scout images obtained prior to the TAVR CT scan are of clinical benefit in access planning for transcatheter interventions. In the presence of challenging body habitus for a transfemoral approach, review of scout images may prompt the team to request additional equipment and extra-long wires for optimizing procedural access success. Abbreviation: CT, computed tomography; TAVR, transcatheter aortic valve replacement.

Figure 3

Optimizing CT femoral overlay presentation. 3D segmentation of the femoral vessels with measurement overlays on the patient’s skeletal overview allows for mimicking of intraprocedural cardiac catheterization fluoroscopic projections used at the time to obtain femoral access. Incorporation of the humerus, pelvic bones, and spinal anatomy provides anatomical landmarks for the implanting team to assist with optimizing delivery sheath positioning and arterial access. Abbreviations: 3D, three-dimensional; CT, computed tomography.

Figure 4

Challenging femoral anatomy. Panel (a) demonstrates extensive endovascular stenting extending into the bilateral common iliac arteries. Panel (b) demonstrates the presence of severe peripheral arterial disease and prior patent surgical femoral-femoral bypass tract. Panel (c) demonstrates a renal transplant grafted to the right common iliac artery. Abbreviation: HU, Hounsfield unit.

Figure 5

3-dimensional CT planning for cerebral embolic protection. Panel (a) demonstrates a bovine aortic arch. Panel (b) demonstrates separate ostiums of the brachiocephalic artery, the left common carotid artery, and the left subclavian artery. Panel (c) demonstrates a challenging carotid tortuosity. Abbreviation: CT, computed tomography.

Figure 6

Double-oblique method for TAVR annulus sizing. Using the multiplanar reformat-guided double-oblique method of the aorta at the level of the aortic annulus, the double-oblique crosshairs are optimized in the sagittal (Panel a) and coronal (Panel b) planes of the aortic annulus to generate the image of the aortic annulus (Panel c) in the axial window. Abbreviation: TAVR, transcatheter aortic valve replacement.

Figure 7

Key TAVR CT aortic root measurements. (a) Double-oblique multiplanar reformat measurements of the aortic annulus are obtained inclusive of diameters, area, and perimeter. (b) Left main and right coronary heights are measured from the inferior rim of the ostium of the coronary vessels to the level of the native aortic annulus plane. (c) Sinus of Valsalva dimensions are assessed in the diastolic phases of the cardiac cycle. Measurements are taken from the center of the left coronary cusp to the opposing wall and repeated for each additional cusp. (d) Sinotubular junction dimensions are measured in diastole to ensure the STJ is wider than the proposed delivery balloon and width of the potential transcatheter heart valve. (e) Three-dimensional transparency postprocessing segmentation of the aorta, the left ventricle, and calcification allows for visualization of the presence or absence of infra-annular LVOT calcification (purple arrow). Abbreviations: CT, computed tomography; HU, Hounsfield unit; LCC, left coronary cusp; LVOT, left ventricular outflow tract; NCC, noncoronary cusp; RCC, right coronary cusp; STJ, sinotubular junction; TAVR, transcatheter aortic valve replacement.

Figure 8

TAVR-in-TAVR redo CT planning assessment for coronary risk obstruction. There are 4 main search patterns for assessing risk of coronary obstruction from TAVR-in-TAVR procedures: (1) coronary obstruction by the initial TAVR device’s leaflet (pink arrow showing long TAVR leaflet with risk of obstructing flow to left main coronary ostia), (2) obstruction of coronary ostia by the frame of the transcatheter heart valve (assessed as distance between the frame of the transcatheter heart valve to associated coronary ostia), (3) presence or absence of commissural alignment: defined as orientation of the implanted transcatheter heart valve’s leaflets away from or opposed to the takeoff of coronary ostia (in this image the TAVR leaflets have commissural misalignment), and (4) risk of sinotubular junction sequestration of blood flow by the implanted transcatheter heart valve. Abbreviation: CT, computed tomography; STJ, sinotubular junction; TAVR, transcatheter aortic valve replacement.

Figure 9

CT-guided coronary risk evaluation. (Panel a) Left main stent is noted to protrude into the level of the sinus of Valsalva of the aortic root. The distance from the left main stent to the opposing wall is 23.8 mm. (Panel b) Balloon inflation of an early generation Sapien TAVR device is noted with the left main stent demarcated. (Panel c) Captures the balloon rupture after contact with the left main stent. Abbreviation: CT, computed tomography; TAVR, transcatheter aortic valve replacement.

Figure 10

Complex CT planning and virtual modeling for TAVR in surgical aortic valve replacement. Panel (a) demonstrates bilateral low coronary heights < 5 mm in height from the base of the SAVR sewing ring to the inferior borders of the left and right coronary arteries. Panel (b) additionally demonstrates coronary obstruction risk from the SAVR leaflets of both the left and right coronary artery ostiums (with each SAVR leaflet measuring >10 mm in length). Panel (c) demonstrates the virtual transcatheter heart valve modeled at the level of the left and right coronary ostium takeoffs with a frame of the virtual valve to opposing coronary ostium distance of <2 mm each. Panel (d) demonstrates CT computer-aided design-generated virtual implant of a balloon-expanded transcatheter heart valve at a 50:50 position. Panel (e) demonstrates a self-expanding Evolut Valve implanted in the SAVR device. Abbreviation: CT, computed tomography; SAVR, surgical aortic valve replacement; TAVR, transcatheter aortic valve replacement.

Figure 11

CT-generated leaflet modification angles for left and right coronary interrogation. Panel (a) demonstrates C-arm angle of LAO 20 CRA 2 as the projection of the long-axis of the catheter (pink arrow) when engaged with maximal coaxiality with the left main, and RAO 35 CAU 4 as the barrel view of the left main catheter to fluoroscopically confirm catheter coaxiality to the angulation of the left main ostium (as depicted by the pink arrow). Panel (b) demonstrates the C-arm angle of LAO 49 CRA 37 as the optimal right coronary catheter angulation for the long-axis view of the sheath (pink arrow) and LAO 1 CAU 16 as the barrel view down the center of the catheter (pink dot) to ensure maximal catheter coaxiality with the axis of the right coronary artery in multiple projections. Abbreviation: CAU, caudal; CRA, cranial; CT, computed tomography; LAO, left anterior oblique; RAO: right anterior oblique.

Figure 12

Multilevel underexpansion of the TAVR valve implantation. Panel (a) shows the 3D volumetric segmentation of the post-TAVR CT in transparency mode. Panel (b) depicts the TAVR device sizing at the level of the aortic rim. Panel (b) depicts the smaller sizing of the TAVR device along the LVOT rim of implantation. Abbreviations: CT, computed tomography; LVOT, left ventricular outflow tract; TAVR, transcatheter aortic valve replacement.

Figure 13

Virtual modeling of TAVR-in-TAVR. In panel (a), the frozen leaflet of the initial CoreValve TAVR implant is highlighted in purple. A balloon-expandable valve is then modeled with a landing zone at the most basilar leaflet insertion portion of the initial TAVR device to show virtual device implantation. In panel (b), given concern for left coronary obstruction, optimal pathway into the left coronary artery ostium is depicted by the pink arrow in multiple C-arm angles. With the CT-guided roadmap, the optimal entry crossing point into the left coronary artery ostium is counted as the third diamond from the aortic rim of the CoreValve device for optimal coaxial entry point into the left main coronary. Abbreviation: CRA, cranial; CT, computed tomography; LAO, left anterior oblique; RAO, right anterior oblique; TAVR, transcatheter aortic valve replacement.

Figure 14

CT-guided neo-LVOT prediction modeling. From left to right, degenerated surgical mitral bioprosthesis is segmented in the confines of the left atrium and the left ventricle. The LVOT cross-sectional area is depicted by the red-dashed line in the central figure. On the far right image, the LVOT cut-plane reflecting the cross-sectional neo-LVOT area is visualized from the surgeon’s perspective from the aortic root into the LVOT. Subtraction of the transcatheter heart valve area from the LVOT area generates the predicted neo-LVOT area demarcated in maroon. Abbreviations: CT, computed tomography; LVOT, left ventricular outflow tract; TMVR, transcatheter mitral valve replacement.

Figure 15

CT-generated TMVR fluoroscopic angles. CT-generated fluoroscopic deployment angle for TMVR valve-in-valve separates the aortic outflow tract from the surgical mitral bioprosthesis to enable implanting physicians to have an alternative imaging modality to visualize the size of the LVOT during valve-in-valve implant. Abbreviations: CRA, cranial; CT, computed tomography; LAA, left atrial appendage; LVOT, left ventricular outflow tract; RAO, right anterior oblique; TMVR, transcatheter mitral valve replacement.

Figure 16

Fluoroscopic visibility of each type of bioprosthesis. Panel (a) demonstrates the different bioprostheses' fluoroscopic visibility by CT. The Epic bioprosthesis has a light annular rim (orange dashed arrow) visible at its atrial portion of the mitral cuff; the Mosaic has radiopaque circles (black arrows) within each distal strut. The entire Mitris frame is radiopaque (black dashed arrows) and visible under fluoroscopy. Panel (b) demonstrates the presence or absence of fluoroscopic landmarks of each bioprosthesis (Color figure can be viewed at wileyonlinelibrary.com) Adapted with permission from CCI Wiley 2021 Wang et al. Comparative differences of mitral valve-in-valve implantation. Abbreviation: CT, computed tomography.

Figure 17

Consistency of TMVR VIV deployment landing zone vs. type of bioprosthesis. The TMVR VIV Epic implantation trended toward greater protrusion into the LVOT across all 3 surgical struts as compared to the Mosaic and the Mitris bioprostheses. The TMVR VIV in Mitris demonstrated greatest ability to land within the depth of the bioprosthesis frame across all 3 surgical struts. Letter 'x' within each plot depicts the mean marker. (Color figure can be viewed at wileyonlinelibrary.com) Adapted with permission from CCI Wiley 2021 Wang et al. Comparative differences of mitral valve-in-valve implantation. Abbreviations: LVOT, left ventricular outflow tract; TMVR, transcatheter mitral valve replacement; VIV, valve-in-valve.

Figure 18

CT-guided planning for transcatheter pulmonic interventions. CT sizing of the pulmonic bioprosthesis is first visualized on axial cross-sections on the left. On the right, CT-generated C-arm fluoroscopic angle of RAO 10 CRA 26 demonstrates the long-axis of the main trunk of the pulmonary artery to the level of the RVOT through the pulmonic bioprosthesis. Note the left main and left anterior descending artery are both segmented in the 3D image to depict the position of the coronary artery with respect to potential balloon inflation and valve implantation at the level of the pulmonic annulus. Abbreviations: 3D, three-dimensional; CRA, cranial; CT, computed tomography; HU, Hounsfield unit; LAD, left anterior descending artery; PA, pulmonary artery; RA, right atrium; RAO, right anterior oblique; RVOT, right ventricular outflow tract.

Figure 19

Asymmetric shape of the pulmonic annulus and surrounding structures. Inverted mip, 3D volumetric, and 3D computer-aided design CT-generated images at the C-arm angle of RAO 24 CRA 52 demonstrate the asymmetrical flaring of the pulmonary arterial trunk and the right ventricular outflow tract. Abbreviations: 3D, three-dimensional; CRA, cranial; CT, computed tomography; PA, pulmonary artery; RA, right atrium; RAO, right anterior oblique; RVOT, right ventricular outflow tract.

Figure 20

Variation in right atria and caval anatomy. Panel (a) demonstrates significantly more superior vena cava to right atrium to inferior vena caval angulation than the patient in Panel (b). Panel (a) additionally demonstrates a smaller IVC than the patient in panel (b). Abbreviation: IVC, inferior vena cava; LAA, left atrial appendage; RA, right atrium; SVC, superior vena cava.

Figure 21

Three patients with severe tricuspid regurgitation and their CTs. Patient (a) has severe volume overload of the right atrium and right ventricle. Patient (b) has enlargement of the right atrium in the superior to inferior dimension, and enlargement of the right ventricle in the mid-RV cavity. Patient (c) has interventricular septal flattening with the right ventricle pointed in a downward direction towards 4 pm consistent with right ventricular volume and pressure overload. Patient (c) additionally has right atrial enlargement in the superior to inferior and z-axis directions. Abbreviation: CT, computed tomography; IVC, inferior vena cava; SVC, superior vena cava.

Figure 22

Depicting right heart failure by 2D TEE vs. angiography vs. CT. 2D transesophageal 4-chamber view of the right ventricle and 2D RAO view of the right ventricular angiogram are not capable of projecting the full 3-dimensional view of the right atrium, right ventricle, and right ventricular outflow tract as demonstrated on CT-generated computer-aided design of the same patient’s right heart. Abbreviations: 2D, two-dimensional; CT, computed tomography; LA, left atrium; LV, left ventricle; RAA, right atrial appendage; RAO, right anterior oblique; RVOT, right ventricular outflow tract; SVC, superior vena cava; TEE, transesophageal echocardiogram.

Figure 23

Step-by-step CT-guided tricuspid evaluation. (a) On the axial cross-sections in the yellow box. The green crosshair is counter-clocked (left panel) until the blue crosshairs are aligned to the basal insertion of the native tricuspid leaflets (yellow box, right panel). (b) On the sagittal cross-sections in the blue box. The red crosshair is counter-clocked (left panel) until the blue crosshairs are aligned to the basal insertion of the native tricuspid leaflets (blue box, right panel). (c) On the coronal cross-sections in the green box. The green crosshair is counter-clocked until the red crosshair matches the parallax of the ascending aorta (green box, right panel). Upon completion of Step C, diameters, area, and perimeter can be measured on the visualized tricuspid annulus. Abbreviation: CT, computed tomography; IVC, inferior vena cava; RV, right ventricle.

Figure 24

CT-generated fluoroscopic angles of the right heart chambers. In the RAO view, the right atrium and the right ventricular long axis are in optimal view. Panning of the C-arm between a RAO cranial and caudal projection alternates between 3-chamber and 4-chamber views of the right ventricle. LAO views of the incomplete tricuspid ring reflect the short-axis transgastric transesophageal view of the tricuspid leaflets. In the LAO view, panning the C-arm angulation between a cranial and caudal orientation helps demonstrate septal to lateral wall sheath and delivery system trajectories and positioning. Lastly, in the AP view, the RA-IVC junction starts to become separated from the right ventricle to help optimize the beginnings of the distinctive RA-IVC landing zone for caval valve implantation. Abbreviation: AP, anteroposterior; CAU, caudal; CRA, cranial; CT, computed tomography; IVC, inferior vena cava; LA, left atrium; LAO, left anterior oblique; LV, left ventricle; RA, right atrium; RA-IVC, right atrium-inferior vena cava; RAO, right anterior oblique; RV, right ventricle.