Which statement is not a valid criterion for stenosis in a graft assessment?

Which statement is not a valid criterion for stenosis in a graft assessment?

• A. 2:1 velocity increase
• B. Focal velocity acceleration
• C. Peak systolic velocity alone
• D. Severe post-stenotic turbulence

Answer: (C)

In graft assessment, diagnosing stenosis relies on how blood flow behaves across a narrowed segment, not on a single velocity value. A true narrowing causes three telltale signs: flow accelerates at the stenosis so the peak velocity is markedly higher there, the velocity at the narrowed site compared with the pre-stenotic segment yields a velocity ratio (often about 2:1 or greater) that signals a hemodynamic gradient, and the downstream flow becomes disturbed, producing turbulence beyond the stenosis. This combination—a focal velocity rise, a substantial velocity ratio, and post-stenotic turbulence—supports the presence of a hemodynamically significant stenosis. Peak systolic velocity by itself, however, is not a reliable criterion. It can be influenced by many factors such as the angle of insonation, overall flow demands, heart function, and graft orientation, without reflecting the true severity of narrowing. Therefore, using PSV alone does not adequately define stenosis, whereas incorporating velocity ratios, focal acceleration, and post-stenotic turbulence provides a more accurate assessment.

In graft assessment, diagnosing stenosis relies on how blood flow behaves across a narrowed segment, not on a single velocity value. A true narrowing causes three telltale signs: flow accelerates at the stenosis so the peak velocity is markedly higher there, the velocity at the narrowed site compared with the pre-stenotic segment yields a velocity ratio (often about 2:1 or greater) that signals a hemodynamic gradient, and the downstream flow becomes disturbed, producing turbulence beyond the stenosis. This combination—a focal velocity rise, a substantial velocity ratio, and post-stenotic turbulence—supports the presence of a hemodynamically significant stenosis.

Peak systolic velocity by itself, however, is not a reliable criterion. It can be influenced by many factors such as the angle of insonation, overall flow demands, heart function, and graft orientation, without reflecting the true severity of narrowing. Therefore, using PSV alone does not adequately define stenosis, whereas incorporating velocity ratios, focal acceleration, and post-stenotic turbulence provides a more accurate assessment.