Recurrent stenosis by duplex scan following carotid endarterectomy

Between June 1984 and January 1986, 155 carotid endarterectomies were performed with routine shunting. Serial duplex scanning was performed during an 18-month period on 124 vessels. The results of this duplex scan review revealed the following data: A normal scan was obtained in 87/124 (70.1%). Recurrent stenosis was identified in 35/124 (28.1%), and an occluded vessel was identified in 2/124 (1.6%). Of the total recurrent stenosis group, recurrent stenosis was graded mild in 22/124 (17.7%), moderate in 7/124 (5.6%), and severe in 6/124 (4.8%). Of the 35 vessels with recurrent stenosis by duplex scanning, 22/35 (62.8%) were in female patients, and 13/35 (37.2%) were in male patients. Of the vessels with severe recurrent stenosis, 5/6 (83%) were in female patients. Recurrent stenosis following carotid endarterectomy is more common than appreciated clinically, and female patients in particular may be more prone to recurrent stenosis.     

Intraoperative duplex ultrasound during carotid endarterectomy.

The purpose of this study was to examine the technical aspects of intraoperative duplex ultrasound (DUS) following carotid endarterectomy (CEA), suggest criteria to differentiate significant lesions requiring immediate surgical revision from normal or benign defects, and evaluate how frequently intraoperative DUS provides useful or unsuspected information. A retrospective study was performed on all patients who had both CEA and intraoperative carotid DUS between January 1, 1990, and January 1, 1995. A total of 155 DUS examinations were performed in 149 patients. Findings were grouped into three categories: normal; minor/insignificant lesions; and hemodynamically significant lesions based on the presence or absence of elevated peak systolic velocities, visible stenosis/thrombus, or intimal flap/dissection. Postoperative status was correlated with intraoperative DUS findings. Ninety-one (59%) examinations performed on 87 patients produced normal findings. Forty-seven (30%) examinations performed on 45 patients showed minor abnormalities consisting of insignificant residual plaque, residual external carotid artery stenoses, small intimal flaps, elevated velocities with no associated anatomic lesion, or an arterial kink. Fourteen patients (9%) had significant findings requiring immediate surgical revision. These consisted of large intimal flaps or dissection in six patients, marked residual plaque and significant stenosis in five patients, thrombus in two patients, and a kink in one patient. Three additional patients (2%) had significant findings but were not revised for various reasons. No significant difference was identified in morbidity or mortality rates between those patients with normal findings, those patients with minor technical defects, and those patients with significant abnormalities undergoing immediate surgical revision. However, two of three patients who had significant abnormalities within the common carotid artery that were not revised suffered perioperative ipsilateral strokes. Intraoperative DUS is a safe and accurate method to assess the technical adequacy of CEA. Intraoperative DUS showed significant lesions in 11% of patients. Identification and immediate repair of significant technical defects may decrease perioperative complication rate and long-term restenosis rate.     

Is routine duplex examination after carotid endarterectomy justified?

Routine follow-up of patients after carotid endarterectomy with duplex scanning is commonly practiced, yet the clinical significance of identifying those with asymptomatic restenosis is unclear. To address this issue we reviewed 120 consecutive patients who underwent 143 carotid endarterectomies from August 1983 to December 1988. One hundred one patients (118 operations) were available for clinical follow-up, and the overall incidence of recurrent symptoms was 6% (6/101). Sixty-three of these patients (78 carotid endarterectomies) had postoperative duplex examination. Two had evidence of residual disease from the time of surgery and were not included in further analysis. Significant recurrent stenosis (greater than 50% diameter reduction) developed in 14 of the remaining 76 arteries (18.2%). Twelve of 14 stenoses remained asymptomatic during follow-up from 18 to 72 months (mean 47.0 months) and did not undergo reoperation. Recurrent ipsilateral hemispheric symptoms developed in two patients with restenosis (14.3%). Four of the 62 arteries without significant recurrent stenosis developed ipsilateral symptoms (6.5%), but none required reoperation during follow-up from 1 to 71 months (mean 31.6 months). Life-table analysis showed no increased risk of transient ischemic attack, stroke, or death in patients with restenosis. This study supports regular clinical follow-up after carotid endarterectomy with emphasis on patient education in the recognition of symptoms. Although duplex scanning may be useful to follow known contralateral asymptomatic disease or evaluate those with recurrent symptoms, its routine use to identify patients with asymptomatic restenosis after carotid endarterectomy may be unnecessary.     

Intra-operative assessment of technical defects after carotid endarterectomy: a comparison between angiography and colour duplex scan

We compared the intra-operative diagnostic value of CDS vs IA-DSA in identifying major and minor technical defects after CEA. Between August 1997 and December 1998, 138 consecutive patients undergoing 141 carotid endarterectomies were intra-operatively investigated with colour duplex scan and intra-arterial digital subtraction angiography. Thirty-six (25.5%) technical defects were identified. Four (11.1%) major defects were detected by both methods and they were immediately corrected. Fifteen (41.6%) minor defects were detected by both methods, thirteen (36.1%) minor defects were detected by colour duplex but ignored by angiography. Angiography detected four (11.1%) kinkings missed with the colour duplex. The overall sensitivity of both methods for major defect was 100%. The sensitivity of colour duplex for minor defects was 87% vs 59% for angiography. On the basis of our study, colour duplex could be considered the choice method for quality control after carotid endarterectomy.     

Duplex scan surveillance after carotid angioplasty and stenting: a rational definition of stent stenosis

OBJECTIVE: A duplex ultrasound (DUS) surveillance algorithm used after carotid endarterectomy (CEA) was applied to patients after carotid stenting and angioplasty (CAS) to determine the incidence of high-grade stent stenosis, its relationship to clinical symptoms, and the outcome of reintervention. METHODS: In 111 patients who underwent 114 CAS procedures for symptomatic (n = 62) or asymptomatic (n = 52) atherosclerotic or recurrent stenosis after CEA involving the internal carotid artery (ICA), DUS surveillance was performed 300 cm/s, diastolic velocity >125 cm/s, internal carotid artery stent/proximal common carotid artery ratio >4) involving the stented arterial segment prompted diagnostic angiography and repair when >75% diameter-reduction stenosis was confirmed. Criteria for >50% CAS stenosis was a PSV >150 cm/s with a PSV stent ratio >2. RESULTS: All 114 carotid stents were patent on initial DUS imaging, including 90 (79%) with PSV <150 cm/s (94 +/- 24 cm/s), 23 (20%) with PSV >150 cm/s (183 +/- 34 cm/s), and one with high-grade, residual stenosis (PSV = 355). During subsequent surveillance, 81 CAS sites (71%) exhibited no change in stenosis severity, nine sites demonstrated stenosis regression to <50% diameter reduction, and five sites developed velocity spectra of a high-grade stenosis. Angiography confirmed >75% diameter reduction in all six CASs with DUS-detected high-grade stenosis, all patients were asymptomatic, and treatment consisted of endovascular (n = 5) or surgical (n = 1) repair. During the mean 33-month follow-up period, three patients experienced ipsilateral, reversible neurologic events at 30, 45, and 120 days after CAS; none was associated with severe stent stenosis. No stent occlusions occurred, and no patient with >50% CAS stenosis on initial or subsequent testing developed a permanent ipsilateral permanent neurologic deficit or stroke-related death. CONCLUSION: DUS surveillance after CAS identified a 5% procedural failure rate due to the development of high-grade in-stent stenosis. Both progression and regression of stent stenosis severity was observed on serial testing, but 70% of CAS sites demonstrated velocity spectra consistent with <50% diameter reduction. The surveillance algorithm used, including reintervention for asymptomatic high-grade CAS stenosis, was associated with stent patency and the absence of disabling stroke.     

Restenosis following carotid endarterectomy. Evaluation by duplex ultrasonography

This study evaluated the efficacy of duplex ultrasonographic scanning in assessing the status of carotid arteries after 155 endarterectomies in 131 patients. Duplex studies were done as early as one month and as late as 96 months postoperatively; 33 patients had serial studies. Only 59 (42%) of 142 arteries had no evidence of irregularity or reduction in diameter at the operative site. An additional 41 (29%) had a reduction in diameter between 10% and 29%; 19 (13%) had reductions of 30% to 49%; nine (6%) from 50% to 69%; six (4%) from 70% to 99%; and eight (6%) were occluded. In 51 vessels, angiographic studies confirmed the duplex findings. Symptoms suggestive of recurrent cerebrovascular disease occurred postoperatively in 25 instances; in only three were the anatomic findings suggestive of lesions appropriate to the symptoms. We conclude that duplex ultrasonographic scanning is a useful technique for assessing carotid arteries after endarterectomy and that postoperative narrowing of vessels occurs more commonly than suspected.     

Assessment of ocular perfusion after carotid endarterectomy with color-flow duplex scanning

PURPOSE: The purpose of this study was to assess the effect of carotid endarterectomy (CEA) on ocular perfusion with the measurement of the ophthalmic artery (OA) and the central retinal artery (CRA) flow velocities with color-flow ocular duplex scanning (ODS). Ocular hemodynamics also were examined in a subset of patients with visual symptoms in an attempt to characterize the origin of the ocular symptoms and their response to surgery. METHODS: Twenty-five patients with internal carotid artery stenoses (>/=70%) underwent 29 CEAs. All the patients underwent ODS for the measurement of the peak systolic velocity (PSV) in the OA and the CRA of the ipsilateral eye before and after CEA. The preoperative and postoperative flow velocities were compared in all the patients and in the patients with and without visual symptoms. RESULTS: The preoperative PSV in the OA was 21.6 +/- 2.2 cm/s and in the CRA was 7.7 +/- 0.7 cm/s. These values were reduced as compared with normative values (OA, 37.8 cm/s; CRA, 10.7 cm/s). After CEA, the PSV increased significantly in both vessels (postoperative OA, 38.6 +/- 2.5 cm/s, P <.0001; postoperative CRA, 12.1 +/- 0.9 cm/s, P =.0008). Fifteen of the 29 CEAs were performed for visual symptoms. The patients with ocular symptoms had significantly lower preoperative PSVs in the CRA as compared with those patients without visual symptoms (CRA with ocular symptoms, 6.5 +/- 0.8 cm/s; CRA with no ocular symptoms, 9.4 +/- 0.9 cm/s; P =.02). The PSV in the OA was not significantly lower in the patients with ocular symptoms. Eight patients (28%) were found to have reversed OA flow before surgery, but only three patients had ocular symptoms. All eight patients had normal antegrade flow in the OA after surgery. CONCLUSION: Severe carotid stenosis may be associated with reduced ocular perfusion, which can be quantitatively evaluated with ODS. Reduced OA and CRA flow velocities are corrected with successful CEA. The patients with ocular symptoms were observed to have significant reductions in CRA flow velocities. Reversed flow in the OA was not a marker for ocular symptoms in this study. ODS can identify global ocular ischemia and may be helpful in the evaluation of patients with atypical visual symptoms or with amaurosis fugax and no evidence of retinal emboli.     

Impact of duplex scanning on carotid endarterectomy

Duplex ultrasound permits safe and accurate assessment of the extracranial vasculature. This paper reports the change in patterns of referral to a specialized vascular unit following its introduction; increased referrals were seen in all specialties except neurology. A widely available and reliable duplex service has revealed more extracranial vascular disease than was previously recognized, and has increased referrals for carotid endarterectomy, thereby increasing surgical workload.     

Magnetic resonance angiography is an accurate imaging adjunct to duplex ultrasound scan in patient selection for carotid endarterectomy

PURPOSE: The purpose of this study was to evaluate the accuracy of magnetic resonance angiography (MRA) for categorizing the severity of carotid disease relative to duplex ultrasound scan and cerebral contrast arteriography (CA) to determine if MRA imaging could replace the need for cerebral angiography in cases of indeterminate or inadequate duplex scan imaging. METHODS: Seventy-four carotid bifurcations in 40 patients undergoing 45 carotid endarterectomies from 1996 to 1998 were imaged with duplex ultrasound scan; MRA (two-dimensional neck and three-dimensional intracranial, time-of-flight technique); and biplanar, digital subtraction cerebral arteriography. Studies were blindly reviewed by one reader who used established threshold velocity criteria for the duplex scan and the North American Symptomatic Carotid Endarterectomy Trial method for MRA and CA to determine the percentage of diameter reduction of the internal carotid artery (ICA). Disease severity was grouped into four categories (< 50%, 50%-74%, 75%-99% stenosis and occlusion), and the results of MRA and duplex ultrasound scan were compared with CA. RESULTS: Sensitivity, specificity, positive predictive value, and negative predictive value for detection of > 50% ICA stenosis were 100%, 96%, 98%, and 100% for MRA and 100%, 72%, 88%, and 100% for duplex ultrasound scan, respectively; similarly, for detection of > 75% ICA stenosis values were 100%, 77%, 76%, and 100% for MRA and 90%, 74%, 72%, and 91% for duplex ultrasound scan, respectively. Both MRA and duplex ultrasound scan accurately differentiated all cases of > 95% stenosis (n = 7) from occlusion (n = 4). Short length ICA flow gaps were present on MRA in all cases of 75% to 99% stenosis and one half of cases of CA-defined 50% to 74% stenosis. In patients with 50% to 74% stenosis, the mean angiographic stenosis was significantly greater when a flow gap was present on MRA (64% +/- 6%) versus no flow gap (57% +/- 7%) (P =.04). There was overall agreement among duplex ultrasound scan, MRA, and CA in 73% of carotids imaged. Of the 24% discordant results between MRA and duplex ultrasound scan, MRA correctly predicted disease severity in all cases, and inaccurate duplex ultrasound scan results were due to overestimation in 83% of cases. The operative plan was altered by CA findings in only one patient (2%) after duplex ultrasound scan and MRA. CONCLUSIONS: MRA can accurately categorize the severity of carotid occlusive disease. Duplex ultrasound scan facilitates patient selection for carotid endarterectomy in most cases, but adjunct use of MRA improves diagnostic accuracy for > 75% stenoses and may obviate the need for cerebral arteriography when duplex scan results are inconclusive or demonstrate borderline disease severity.     

Accuracy of duplex scanning in the detection of stenosis after carotid endarterectomy

The results of duplex ultrasonography in grading stenosis after carotid endarterectomy (78 sites) were compared with those of contrast angiography in 71 patients studied for recurrent or contralateral occlusive disease of the carotid bifurcation. Duplex and angiographic studies were performed within one month of each other at a mean postoperative interval of 44 months (range 3 to 122 months). Stenosis of the common carotid (CCA) and internal carotid artery (ICA) was classified into five disease categories (normal or less than 15% diameter reduction [DR], 16% to 49% DR, 50% to 75% DR, greater than 75% DR, and occlusion). The overall accuracy of duplex scanning compared with angiography in predicting recurrent carotid bifurcation disease was 83%, a level of agreement similar to classification of disease involving the nonoperated, contralateral bifurcation (overall accuracy 87%). Recurrent stenosis (greater than 50% DR) or occlusion of the CCA or ICA after endarterectomy was identified with an accuracy of 97%. Overestimation of severity of recurrent stenosis accounted for 11 of 13 duplex classification errors (85%). Presence of moderate (30% to 50% DR) recurrent stenosis of the CCA, tortuosity of the ICA, and severe contralateral carotid bifurcation disease were associated with velocity spectra that predicted a more severe recurrent stenosis at the endarterectomy site compared with angiographic grading. The level of agreement between duplex scanning and angiography was comparable to the interobserver variability in angiographic interpretation. The accuracy reported justifies the use of duplex scanning to grade the severity of carotid bifurcation recurrent stenosis and to follow these lesions for disease progression.     

Is duplex follow-up cost-effective in the first year after carotid endarterectomy?

Recent reports have suggested that duplex scanning is an ideal method to noninvasively assess the incidence of recurrent carotid stenosis. However, the timing and frequency of the follow-up studies are controversial. In the present study, 150 patients underwent 173 carotid endarterectomy procedures over a 2 year period. In the postoperative period, a total of 210 duplex studies were carried out on 117 carotid arteries. 21.4 percent of the 117 arteries studied had recurrent stenosis of 16 percent or greater at a mean postoperative follow-up of 15.2 +/- 3 months. Recurrent stenoses were detected early after operation; 96 percent were detected at or before 15 months postoperatively. Patients with recurrent stenoses remained stable and had infrequent symptoms. Several risk factors placed the patient at increased risk for recurrent carotid stenosis: presence of contralateral disease (defined as stenosis of 50 percent or greater), use of tacking sutures, and continued smoking in the postoperative period. Although it remains important for researchers to thoroughly investigate the natural history of atherosclerosis of the extracranial carotid artery, including those changes that occur after carotid endarterectomy, our results indicate that frequent duplex scanning in the first postoperative year is unnecessary and is not cost-effective. Duplex follow-up studies 1 and 12 months after carotid endarterectomy are sufficient for assessing the problem of recurrent stenosis in the first postoperative year.     

Carotid artery endarterectomy solely based on duplex scan findings

The purpose of this study was to review experience with carotid artery surgery based on findings obtained solely from duplex scanning with special regard to unexpected findings during surgery and the early outcome. From January 1993 through December 1999, 271 consecutive patients underwent 287 carotid endarterectomies (CEAs), 229 (80%) of which were performed solely based on duplex scan findings. During the study period 5,932 carotid artery duplex scans were performed in 4,466 patients. Of 589 patients with internal carotid artery (ICA) stenosis 70%, 246 underwent CEA compared to 25 of 156 with 50-69% ICA stenosis. The indications for CEA were transient ischemic attack (TIA) in 88 (30.7%), amaurosis fugax in 60 (20.9%), previous stroke in 91 (31.7%) and asymptomatic disease in 48 (16.7%) cases. There were no statistically significant differences between the groups operated on with and without preoperative angiography with respect to the indications for surgery, associated risk factors, or the degree of stenosis on the contralateral side. In patients undergoing surgery without angiography, there were no unexpected findings that influenced the performance of surgery, in all except 1. There were no significant differences in perioperative morbidity and mortality in patients undergoing surgery with and without conventional angiography. The combined mortality and major stroke rates were 3.4% and 2.2%, respectively. It is concluded that CEA can safely be performed without preoperative angiography in cases with conclusive duplex scan findings.     

The post endarterectomy carotid bruit. Evaluation by Duplex scan

The presence of a bruit after carotid endarterectomy may indicate a persistent or recurrent lesion. The authors noninvasively evaluated, by Duplex scanning, 18 asymptomatic postoperative patients who underwent a total of 23 carotid endarterectomies and who developed a postoperative bruit to determine the significance of the bruit. Eleven men and seven women were studied from 6 weeks to 2 years postsurgery. Ages ranged from 49 to 75 years (63.6 +/- 8.0 years). Indications for endarterectomy were: transient ischemic attacks (including amaurosis fugax), 17 vessels; completed stroke with significant functional recovery and residual carotid disease, 3 vessels; and asymptomatic bruit with hemodynamically significant carotid stenosis, 3 vessels. Each patient had a Duplex scan performed to noninvasively evaluate the carotid artery. All scans were independently reviewed by two observers. Real-time B images were interpreted as normal in 14 vessels, mild thickening in eight vessels, and moderate thickening in only one vessel. Doppler recordings demonstrated a spectral range of 15-40 cm/sec (26 +/- 8 cm/sec). Ratio of velocity in the internal carotid artery to common carotid artery (VIC/VCC) ranged from 0.389 to 1.281 (0.779 +/- 0.250). This study demonstrates that the presence of a postoperative carotid bruit does not necessarily signify the presence of residual carotid disease or a hemodynamically significant lesion.     

Outcome after carotid endarterectomy for asymptomatic carotid stenosis

Objective: To compare the long-term outcome in patients with asymptomatic carotid stenosis (ACS) among those treated with carotid endarterectomy (CE) or medical therapy.

Background: Until randomized trials are completed, treatment of ACS will depend on identification of subgroups likely to benefit from CE.

Methods: A retrospective cohort study was done on 215 patients with ACS: 107 underwent CE, and 108 were treated medically (MED). A neurologist reviewed medical records and performed a telephone interview to detect outcome (stroke and death). Mean follow-up was 3.8 years; only 4% were lost to follow-up.

Results: Among CE patients, there was a 4.7% risk of postoperative ipsilateral stroke within 30 days. Four of five postoperative strokes occurred among patients with prior contralateral symptoms. There was no significant difference between CE and MED in the cumulative lifetable 5-year risk of ipsilateral stroke, any stroke, or survival free of any stroke. Among diabetics, however, there were no ipsilateral strokes at 5 years after CE compared to 20% in MED (p = 0.03). Excluding postoperative complications, the 5-year risk of ipsilateral stroke was reduced among CE patients who “ever smoked” (CE 1%, MED 8%, p = 0.03) and the 5-year risk of any stroke was reduced among CE patients who had no prior myocardial infarction (CE 6%, MED 16%, p=0.02). Among those with prior contralateral carotid territory symptoms, the 5-year risk of any stroke was worse in the MED patients (CE 5% MED 32%, p=0.004). Among CE patients, a Cox proportional hazards model determined that the independent predictors of worse long-term outcome were: a history of myocardial infarction; admission systolic blood pressure greater than 160 mm Hg; and age greater than 65.

Conclusion: The approach to patients with ACS will await completion of large, randomized clinical trials, now in progress. Even if these studies are negative, there may remain specific subgroups of patients who show clear benefit from carotid endarterectomy.