What CT scan protocol is recommended for Transcatheter Aortic Valve Replacement (TAVR) evaluation?

CT Scan Protocol for TAVR Evaluation

For TAVR evaluation, a CTA chest with IV contrast for aortic root assessment and CTA abdomen and pelvis with IV contrast for vascular access evaluation are the recommended imaging protocols. 1

Comprehensive CT Protocol Components

Aortic Root Assessment

• CT Type: ECG-synchronized cardiac CT with IV contrast
• Image Acquisition Parameters:
  • Thin slice collimation ≤1 mm for the aortic root 1
  • ECG-gated acquisition for the aortic root to minimize motion artifacts 1
  • Contrast enhancement focused on the aortic root and valve apparatus

Vascular Access Evaluation

• CT Type: CTA of abdomen and pelvis with IV contrast
  • Can be performed without ECG synchronization 1
  • Reconstructed slice thickness ≤1.5 mm for peripheral vasculature 1
  • Coverage from aortic arch through femoral arteries

Technical Considerations

Contrast Administration

• Use at least a 20-gauge IV access, preferably in an antecubital vein 1
• Contrast volume typically between 50-100 cc 1
• For patients with impaired renal function:
  • Consider lower flow rates (as low as 3 ml/s)
  • Use lower tube potential (down to 80kVp)
  • Implement multi-phasic contrast injection protocols 1
  • Consider spectral CT with monoenergetic 40 keV reconstruction which allows for lower contrast volumes while maintaining image quality 2

Patient Preparation

• Maintain adequate fluid intake prior to examination
• For patients with eGFR ≥30 ml/min/1.73 m², no pre-hydration is required 1
• For patients with eGFR <30 ml/min/1.73 m², consider pre-hydration and contrast volume reduction 1
• Important: Routine beta-blockade is not recommended due to risk in severe aortic stenosis patients 1
• Contraindication: Sublingual nitrates are contraindicated in patients with significant aortic stenosis 1

Imaging Volume Coverage

• The complete imaging volume should include the aortic root, aortic arch, and ilio-femoral access route 1
• For comprehensive evaluation, ensure visualization of:
  • Entire aortic root for annular measurements
  • Coronary ostia height and orientation
  • Ascending aorta, arch, and descending thoracic aorta
  • Abdominal aorta and iliofemoral vessels for access planning 3

Special Considerations

Renal Impairment

• In patients with advanced CKD, consider:
  • Ultra-low contrast protocols using spectral CT techniques 2
  • In extreme cases, "zero contrast" TAVR planning has been described using calcifications as landmarks, though this is not standard practice 4
  • Single low-volume contrast injection protocols (as low as 60 mL) have shown comparable image quality to standard protocols 5

Key Measurements Required

• Aortic annulus dimensions (area, perimeter, diameters)
• Distance from annulus to coronary ostia
• Aortic root dimensions (sinus of Valsalva, sinotubular junction)
• Aortic valve calcification pattern and severity
• Iliofemoral vessel diameters, tortuosity, and calcification 6

Common Pitfalls to Avoid

• Inadequate contrast timing leading to poor opacification of the aortic root
• Insufficient ECG-gating causing motion artifacts in the aortic root assessment
• Failing to assess alternative access routes (subclavian/axillary, direct aortic) in patients with unsuitable iliofemoral access
• Underestimating the impact of vessel tortuosity and calcification on access site selection
• Inadequate coverage of the entire vascular pathway from access site to aortic valve

By following this comprehensive CT protocol, you will obtain the necessary anatomical information for appropriate valve sizing and access route planning, which are critical for successful TAVR outcomes and reduced procedural complications.