Table 1.
Evidence of alterations in blood velocity and blood flow as a consequence of insonation angle
| Theoretical | ||||||
|---|---|---|---|---|---|---|
| Insonation Angle |
Velocity (cm/s) |
Blood Flow (ml/min) |
% Δ from 60° | FMD (%) | Shear (s−1) | FMD/Shear |
| 40° | 3.52±0.46 | 24.8±8.3 | −49% | 7.0 | 33.52 | 0.21 |
| 50° | 4.24±0.57 | 29.5±9.9 | −25% | 7.0 | 40.38 | 0.17 |
| 60° | 5.27±0.50 | 36.7±11.1 | 0% | 7.0 | 50.19 | 0.14 |
| 70° | 7.97±1.07* | 55.5±18.7 | 51% | 7.0 | 75.90 | 0.09 |
| 80° | 15.69±2.12* | 109.4±36.8* | 197% | 7.0 | 149.43 | 0.05 |
*
Significant (p< 0.05) from 60°. Values are mean ±SD.
This table documents the actual blood velocity and blood flow as a function of different insonation angles and the theoretical degree of potential error associated with different angles of insonation that will occur when normalizing FMD for shear.