Which of the following is NOT listed as a reason to use retrograde angiography?

• A. Reduces radiation exposure during the procedure
• B. Significantly enhances visualization of hibernating lumens
• C. Shows true length of occlusions
• D. Enhances morphology of CTO caps

Answer: (A)

Retrograde angiography in CTO procedures is used to visualize the vessel from the distal side through collateral pathways, helping to plan crossing strategies and understand the occlusion more completely. It significantly enhances visualization of hibernating lumens, allowing you to see areas that still have some flow patterns despite the blockage and identify viable channels. It also helps determine the true length of the occlusion by tracing the segment from the distal cap back toward the proximal cap, which is essential for selecting devices and planning the approach. Additionally, it clarifies CTO cap morphology, revealing the shape and borders of the proximal and distal caps to guide entry point and technique. Reducing radiation exposure is not a listed reason to use retrograde angiography; in practice, this approach can increase fluoroscopy time and radiation dose due to the extra steps and collateral-channel work involved.