Technical Recommendations for Computed Tomography Guidance of Intervention in the Right Ventricular Outflow Tract: Native RVOT, Conduits and Bioprosthetic Valves: A White Paper of the Society of Cardiovascular Computed Tomography (SCCT), Congenital Heart Surgeons’ Society (CHSS), and Society for Cardiovascular Angiography & Interventions (SCAI)

Figures

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  Figure 1. Determining etiology of RVOT dysfunction. Figure 1 illustrates hypoattenuated leaflet thickening (HALT) with restricted leaflet motion (B) causing increased gradient after TPVR. This can be progressive but may be treatable medically. Image C is an example of endocarditis with vegetation in an RVOT conduit after Rastelli procedure. Calcified (D) and non-calcified (E) leaflet thickening are seen within a bioprosthetic pulmonary valve. RVOT, right ventricular outflow tract; TPVR, transcatheter pulmonary valve replacement.

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  Figure 2. Dynamism of the native and patched RVOT: Longitudinal shortening. Longitudinal shortening describes the change in pulmonary annulus to pulmonary bifurcation length in the long axis of the pulmonary artery during the cardiac cycle. On the left (A), 2D images in systole and diastole illustrate longitudinal shortening of the MPA in a patient after transannular patch with an aneurysmal RVOT. The contractile portion of the RVOT is smaller in systole but the patched RVOT and MPA are often enlarged. The RVOT in a patient with an intact annulus tends to be smaller in systole (B). These images illustrate the importance of using the longest linear dimension to determine potential landing zone length and the maximal RVOT dimension to assess feasibility of TPVR. RVOT, right ventricular outflow tract; TPVR, transcatheter pulmonary valve replacement

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  Figure 3. Dynamism of the native and patched RVOT: Pulsatility and eccentricity/ellipticity. This case illustrates circumferential pulsatility and ellipticity of the short axis of the annular plane of a dilated patched RVOT. Note the difference in short axis area and in minor and major diameter during systole and diastole. Major and minor diameter, area, perimeter, perimeter derived (average) diameter should be measured at the distal RVOT, the annular plane and the mid MPA. The maximal dimensions at the potential landing zone are used to assess feasibility of TPVR. RVOT, right ventricular outflow tract; TPVR, transcatheter pulmonary valve replacement.

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  Figure 4. Examples of virtual valve placement for TPVR. These two images are examples of a virtual valve placement within the 3D data set of the native RVOT for the Alterra pre-stent (right) and the Harmony valve (left). RVOT, right ventricular outflow tract; TPVR, transcatheter pulmonary valve replacement.

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  Figure 5. Standard measurement planes in the RVOT. This 3D reconstruction illustrates the standard measurement planes in the RVOT, and example measurements from a short axis image of the RVOT. The landing zone of TPVR valves will be between the annulus to the PA bifurcation, or from the distal RVOT past the PA bifurcation for self-expanding valves. Note the eccentricity of the mid MPA measurement. RVOT, right ventricular outflow tract; TPVR, transcatheter pulmonary valve replacement.

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  Figure 6. Examples of variation in branch pulmonary artery anatomy. (A) A 3D reconstruction illustrating narrowed branch pulmonary arteries from the distal RVOT, (B) Criss-cross branch pulmonary arteries and (C) diffusely narrowed pulmonary arteries from the distal conduit after unifocalization in a patient with major aortopulmonary collateral arteries (MAPCAs). In these cases, there is no significant distance between the branch pulmonary artery take-off and the posterior pulmonary artery (ridge of bifurcation), which has implications for placement of self-expanding valves. (D) The usual orientation of the branch pulmonary arteries after the arterial switch operation and the LeCompte maneuver with the innominate vein overlying the branch pulmonary arteries. There is a relatively short neo-RVOT directly anterior to the neo-aorta and branch pulmonary arteries on the right and left side of the aorta. Note the origin of the coronary arteries from the right and left sides of the neo-aorta. RVOT, right ventricular outflow tract.

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  Figure 7. Classification native RVOT/MPA anatomic shape (Source: Schievano et al).83 Understanding the anatomic substrate of the native RVOT helps determine the optimal landing zone for the proposed TPVR. RVOT, right ventricular outflow tract; TPVR, transcatheter pulmonary valve replacement.

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  Figure 8. Recommended native RVOT reporting elements. ∗ Many patients will have prior advanced imaging and the CT is done specifically to assess the RVOT. Some centers may use an ECG gated CCT scan to both assess RV size and function in addition to planning for percutaneous PVR. If so, the RV volumes and EF can be reported. EF, ejection fraction; IVC, inferior vena cava; MPA, main pulmonary artery; PA, pulmonary artery; RVOT, right ventricular outflow tract.

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  Figure 9. Example native RVOT perimeter plots. Example perimeter plots with the potential valve positions for Alterra (top) during systole (left) and diastole (right) and for Harmony (bottom) displaying both diastolic (blue line) and systolic (red line) measurements. The black lines represent the unconstrained Alterra and Harmony valve within patient plots with the perimeter-derived radius on the x-axis. The perimeter plots are constructed to assess device fit and to evaluate different potential landing zones within the RVOT. The green areas in the inflow and outflow of the THV device represent device interaction (oversizing) with the anatomy, which is needed for anchoring. The valve housing unit is located in the waist of the device. (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)

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  Figure 10. Evaluation of RVOT calcification. The image on the left (A) is a 3D reconstruction showing extensive conduit calcification, which is also visualized on both the short axis and long axis of the RVOT 2D images (B/C). The calcification is noted to be circumferential in the proximal conduit and remains extensive through the lateral conduit and into the branch pulmonary artery, which has been patched. RVOT, right ventricular outflow tract.

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  Figure 11. Recommended RVOT reporting elements (Bioprosthetic Valve or Conduit). ∗ Many patients will have had prior advanced imaging and the CT is done specifically to assess the RVOT. Some centers may use an ECG gated CCT scan to both assess RV size and function in addition to planning for percutaneous PVR. If so, the RV volumes and EF can be reported. IVC, inferior vena cava; MPA, main pulmonary artery; PA, pulmonary artery; RVOT, right ventricular outflow tract.

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  Figure 12. Potential for coronary artery compression based on coronary course related to the RVOT. These images show coronary arteries coursing between the aorta and the RVOT, with potential for compression between the great arteries (A/B), or adjacent to a narrowed conduit (C/D). A coronary artery reimplanted posterior to the neo-RVOT after arterial switch operation may also be at risk for compression from the anterior vessel (E). RVOT, right ventricular outflow tract.