TAVR (Transcatheter Aortic Valve Replacement) is a non-surgical alternative for replacing a calcified, stenotic aortic valve. Comprehensive CT planning is mandated before the procedure to evaluate several critical anatomical metrics.
1 Aortic annulus sizing
The aortic annulus is a non-circular structure — 2D echocardiography frequently underestimates its size. CT provides accurate 3D planimetric measurements.
- Measurements are taken during mid-systole (20–40% of the R-R interval) to capture the maximal and stabilized valve opening.
- Sizing rules. The prosthesis generally should not be > 15% oversized or > 5% undersized compared to the native annulus.
Improper sizing risks post-procedural paravalvular leak (undersizing) or annular rupture (oversizing) — both of which can be catastrophic.
2 Coronary ostia heights
If the coronary ostia are located too low, deploying the new valve could displace the native calcified leaflets over the ostia — causing a catastrophic coronary occlusion.
Measure the height of both LCA and RCA ostia from the annulus plane. Low ostia (typically < 10–12 mm) may require alternative valve selection or coronary protection during deployment.
3 Vascular access
A non-gated CT angiogram of the chest, abdomen, and pelvis determines if a transfemoral approach is viable. Most transcatheter valves require:
- Minimum common femoral artery diameter ≥ 6 mm
- Minimal calcification and tortuosity of the iliofemoral tree
- Absence of dissection
If transfemoral access is unsuitable, alternative routes include transapical, subclavian, or transcaval.
4 Co-planar angles
CT datasets can predict the optimal fluoroscopic projection angles (orthogonal to the native valve plane) for the catheterization lab. This simulation:
- Substantially reduces the need for repeat aortograms
- Saves procedural time
- Reduces radiation exposure
- Lowers contrast administration