TIMI flow grading of distal runoff in coronary vessels

• Distal runoff is the blood flow in the post stenotic region of a blood vessel
• Adequate distal runoff is an important factor in the success of vascular grafts
• Poor distal runoff promotes thrombosis formation within the graft – the risk is even more in prosthetic grafts

How to assess distal runoff?

• Angiography can be used to assess distal runoff – TIMI (Thrombolysis In Myocardial Infarction) flow grading
• Based on the amount of contrast material that reaches the distal segment and the rate of clearance of contrast in distal segment, there are 4 TIMI flow grades
  • Grade 3 – Good opacification of distal segment with rapid clearance of contrast material as in the proximal segment
  • Grade 2 – Good opacification of distal segment with slow clearance of contrast material
  • Grade 1 – Poor opacification of distal segment
  • Grade 0 – Contrast material does not reach distal segment