|
| Classification | Velocity (cm/sec) | Image characteristics |
|
| Normal | Mid graft PSV > 150 cm/sec | No visible narrowing |
| Distended outflow veins |
| Anastamosis PSV > 300 cm/sec, chaotic, disorganized flow | Aneurysms, puncture sites, perigraft |
| fluid may be visible |
|
| Moderate stenosis | Ratio of PSV at stenosis to PSV at 2 cm | Decrease in lumen diameter |
| beyond anastamosis if normal-appearing <3 | Echogenic narrowing |
| Wall abnormalities |
|
| Severe stenosis | Marked velocity acceleration at stenotic area | Intraluminal echogenicity < 2 mm |
| lumen >50% diameter reduction |
| Ratio of PSV at stenosis to PSV at 2 cm | Marked reduction in lumen |
| beyond anastamosis if normal-appearing >3 | diameter with color doppler |
|
| Inflow Stenosis | Peak systolic velocities will increase at the site of | Intraluminal echogenicity |
| stenosis with monophasic and diminished | < 2 mm lumen at velocity acceleration |
| waveforms distal |
| Flow acceleration with graft compression at |
| outflow anastamosis |
|
| Outflow stenosis | Mid graft PSV < 100 cm/s | Intraluminal echogenicity |
| Distal vein > 300 cm/sec | < 2 mm lumen velocity acceleration |
| Velocity at the proximal anastamosis will diminish | Prominent collateral veins around outflow |
| in proportion to severity of venous outflow stenosis |
|
| Occlusion | No doppler signal | Intraluminal echogenicity |
| Graft walls appear collapsed |
| Occluded vein may not be visible |
|
