| Autor: |
Currie, I.C., Wilson, Y.G., Baird, R.N., Lamont, P.M. |
| Zdroj: |
European Journal of Vascular and Endovascular Surgery; January 1996, Vol. 11 Issue: 1 p29-35, 7p |
| Abstrakt: |
Objectives:: 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 (200ml/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 >= 15% of the resting distal pressure (% @DP), represented a significant stenosis. Results:: There was improved correlation between Doppler indices and %@DP 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 receiver operator characteristic (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. |
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