Intraoperative duplex monitoring of the carotid bifurcation for the detection of technical defects.

OBJECTIVES: Intraoperative Duplex examination can be used to identify technical imperfections during carotid endarterectomy. The objectives of this study were: (1) to evaluate the technical feasibility of intraoperative Duplex; (2) to compare Duplex findings with contrast arteriography; (3) to correlate intraoperative Duplex findings with postoperative complications and with Duplex data obtained during follow-up. DESIGN: Prospective clinical study. SETTING: Department of Vascular Surgery, Catharina Hospital, Eindhoven, The Netherlands. MATERIALS: 44 patients underwent Duplex scanning at the completion of carotid endarterectomy. In addition intraoperative arteriography was performed in the first 16 consecutive patients. Follow-up included a Duplex examination at three monthly intervals during the first postoperative year. OUTCOME MEASURES: Technical defects and flow disturbance at the time of surgery, and postoperative restenosis. RESULTS: At contrast arteriography a distal intimal ridge with 15-20% diameter reduction was observed in two, an occlusion of the external carotid artery in three and moderate kinking in one patient. All abnormalities were identified at Duplex imaging. In none of the cases were the Duplex findings considered an indication to re-explore the endarterectomised internal carotid artery. Postoperative complications occurred in six patients: three strokes, two transient ischaemic attacks and two internal carotid occlusions (in one patient combined with a stroke). Severe spectral broadening (spectral class D) correlated significantly with early postoperative complications (p = 0.027). In contrast, moderate defects on Duplex imaging did not correlate significantly with early complications. Duplex examination during the first year of follow-up demonstrated recurrent stenosis in four patients. Intraoperative spectral broadening did not correlate significantly with the development of common or internal carotid restenosis. However, external carotid recurrent stenosis was positively related to intraoperative flow disturbance (p = 0.0003). CONCLUSION: Duplex scanning is easy to use after completion of carotid endarterectomy. There is good agreement between intraoperative Duplex scanning and contrast arteriography. Extensive spectral broadening of the Doppler velocity signal is associated with an increased prevalence of early postoperative complications. Restenosis at follow-up appears to be related to severe flow disturbance as was demonstrated for the external carotid artery.

Stenosis development at the distal anastomosis of prosthetic bypasses for aortoiliac occlusive disease. Incidence and accuracy of colour flow duplex in the diagnosis.

When bypasses for aortoiliac occlusive disease fail they often do so because of a stenosis at the distal anastomosis. To assess the incidence of stenotic lesions and to establish the diagnostic reliability of colour-flow Duplex scanning, we investigated 103 aortoiliac and aortofemoral bypasses using intravenous (i.v.) digital subtraction angiography (DSA) as the reference method. Stenotic lesions at or just beyond the distal anastomosis were identified by i.v. DSA in 30 patients. The stenosis had a 30-49% diameter reduction (DR) in 10, 50-79% DR in 17 and 80-99% DR in three patients. The incidence of stenoses identified within the first 3 years following the operation was 33%, in the period of 3-6 years 20%, in the period of 6-9 years 32% and for bypasses longer than 9 years after the operation 50%. Colour-flow imaging had a 89% sensitivity in identifying the presence and location of distal anastomotic stenosis and a 95% specificity of ruling out significant lesions. A threshold value of 0.65 of the index between the peak systolic velocity (PSV) at a normal vascular segment and the maximum PSV at the side of stenosis demonstrated lesions with a sensitivity of 86% and a specificity of 90%. Prophylactic repair of a high grade stenosis (> 70% DR) was performed in only two patients. Colour-flow Duplex is accurate in identifying distal anastomotic stenoses. Although the precise incidence of these lesions can be determined only by a prospective surveillance study, available data suggests a low yield of cases requiring prophylactic repair.(ABSTRACT TRUNCATED AT 250 WORDS)

Impact of a color-flow duplex surveillance program on infrainguinal vein graft patency: a five-year experience.

PURPOSE AND METHODS: The contribution of color-flow duplex surveillance to improving vein graft patency was evaluated in two patient groups after 201 infrainguinal bypass procedures were performed during a 5-year period. Incidence of revision procedures and the primary and assisted primary patency rates were compared for 160 bypass grafts monitored during the first 2 years by use of color-flow duplex scanning of the vein graft and adjacent arterial segments (color-flow surveillance group) versus 41 bypass grafts monitored by use of clinical assessment alone (clinical follow-up group). Only grafts that were patent after the first postoperative month are considered. RESULTS: The two groups were comparable with regard to most of the pertinent clinical factors. Stenotic lesions were identified in 58 bypass grafts, and severity was determined by use of intraarterial digital subtraction angiography. Eighteen bypass grafts with stenoses did not undergo a revision for reasons that were determined by the doctor, the hospital, or the patient. The occlusion rates of revised and nonrevised stenotic grafts were compared for lesions of different severity. None of the grafts for stenoses with 30% to 49% diameter reduction (DR) failed during follow-up. Occlusion occurred in 57% of the nonrevised and 9% of revised grafts (p = 0.047) for stenoses with 50% to 69% DR. Stenoses with 70% or greater DR were associated with graft failure in 100% of nonrevised bypasses and in 10% of revised grafts (p = 0.004). The assisted primary patency rate was higher in grafts that underwent color-flow surveillance compared with grafts with that underwent clinical follow-up (3-year patency rates of 91% and 72%, respectively; p = 0.004). The independent correlation of color-flow surveillance with higher patency rates was demonstrated in a proportional hazard analysis. The relative risk (probability of occlusion) in color-flow surveillance grafts is less than one third of the relative risk in bypass grafts that underwent clinical follow-up. CONCLUSIONS: We conclude that revision procedures were more optimally used during color-flow surveillance, whereas asymptomatic stenotic graft lesions are missed with clinical follow-up, which results in a higher percentage of graft failures. Overall graft patency rates can be improved with use of color-flow duplex surveillance and repair of significant stenotic lesions.