Detection of sub-critical arterial stenoses by hyperaemic Doppler.
OBJECTIVE
This study assessed the potential of hyperaemic Doppler to detect sub-critical stenoses using a flowrig model.


METHODS
Pulsatile flow of a blood substitute was produced in a compliant circuit. A cadaver carotid artery, constricted by a silk suture produced a variable, focal stenosis. Forty-seven stenoses were created in five arteries. Pressure gradients and Doppler measurements were recorded simultaneously across each stenosis at low (200 ml/min) and high (400 ml/min) flow rates. The change in peak velocities between the arterial segment 2cm proximal to the stenosis (V1), and the stenotic jet (V2) were used to calculate three Doppler indices: (i) V2/V1 ratio, (ii) V2-V1 difference, (iii) a modified 'Bernoulli' value. A high flow pressure gradient of > or = 15% of the resting distal pressure (% delta P), represented a significant stenosis.


RESULTS
There was improved correlation between Doppler indices and % delta P at high flow (r = 0.87 to 0.88) compared to low flow rates (r = 0.81 to 0.84). Optimum V2/V1 cut off values were determined by received operator characteristics (ROC) curve analysis. At low flow five sub-critical stenoses were not detected (sensitivity 82.8%) yet all but one of these lesions were identified at high flow (sensitivity of 96.6%). The V2-V1 and Bernoulli indices did not improve on the discriminant ability of the V2/V1 ratio.


CONCLUSIONS
The V2/V1 ratio is sensitive to haemodynamic changes at enhanced flow rates across ideal arterial stenoses. The potential of hyperaemic Doppler to detect sub-critical lesions and so avoid intraarterial pressure measurements deserves further in vivo study.
Currie
I C
IC
Department of Vascular Surgery, Bristol Royal Infirmary, U.K.
Wilson
Y G
YG
Baird
R N
RN
Lamont
P M
PM
D001157:Arterial Occlusive Diseases / Q000000981:diagnostic imaging* / Q000503:physiopathology; D001783:Blood Flow Velocity; D003251:Constriction, Pathologic; D006801:Humans; D006940:Hyperemia; D066298:In Vitro Techniques; D008955:Models, Cardiovascular; D008961:Models, Structural; D011673:Pulsatile Flow; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D018608:Ultrasonography, Doppler