Assessment of intraoperative duplex sonography during carotid endarterectomy]

INTRODUCTION: Carotid endarterectomy (CEA) for prevention of strokes mandates a high amount of experience and a meticulous surgical technique. Intraoperative morphologic as well as hemodynamic monitoring of the endarterectomized arteries is rarely performed. The purpose of this study was to determine the value of intraoperative colour-coded-duplex-sonography to recognize eventual intraoperative technical problems that might result in serious cerebral damage. METHODS: Prospective analysis of the medical data of all patients who underwent CEA for treatment of high-grade carotid stenosis between 1996 and 1999. Adequacy of the repair was assessed intraoperatively by duplexsonography. RESULTS: Of 142 consecutive patients with a median age of 68 (43-84) years, 104 (73 %) were men and 38 (27 %) were women. 9 patients (6 %) had bilateral CEAs. Intraoperative duplexsonography revealed abnormalities during 11 (7 %) of 151 CEAs. 4 (3 %) were considered major and underwent immediate revision. There was one (0.7 %) temporary neurologic deficit (hyperperfusion syndrome) and 2 (1.3 %) cases of fatal intracerebral hemorrhage. 6 (4 %) postoperative surgical complications occurred, i. e. 3 cases of major wound hematoma (with revision) and 3 cases of temporary cranial nerve palsy. Median length of follow-up was 11 (3-35) months. No late neurologic event occurred during follow-up. 5 (3 %) patients developed asymptomatic restenosis. DISCUSSION: Routine intraoperative duplexsonography is a valuable and reliable diagnostic tool to detect correctable technical problems during CEA that subsequently may lead to neurological deficits, fatal stroke or a high incidence of restenosis.     

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.     

彩色多普勒超声在颈动脉内膜剥脱术中的应用

目的探讨术中超声检查在颈动脉内膜剥脱术（CEA）中应用的价值。方法收集因颈内动脉重度狭窄而接受颈动脉内膜剥脱术的21例患者,术中应用超声扫查确定斑块位置、病变长度,判断颈动脉管腔内有无游离动脉内膜及小血栓等。参照Panetton标准,将术中超声检查结果分为正常、轻度异常和显著异常。结果9例患者于颈动脉缝合后超声检查发现细条带状高回声,共14处,12处轻度异常均为长度〈3mm的游离内膜片,未予特殊处理;2处显著异常,其中1处为缝入动脉管腔内的动脉外膜,1处为细带状血栓,对此2例患者均于超声引导下再次切开颈动脉、去除游离物。术后3天复查超声显示游离内膜片均自行愈合。结论CEA术中应用超声监测可以明确颈动脉斑块位置、病变范围及形态、颈动脉狭窄程度,及时发现内膜损伤等手术并发症,有助于降低术后脑卒中率及死亡率。     

Comparison of intraoperative completion flowmeter versus duplex ultrasonography and contrast arteriography for carotid endarterectomy

Intraoperative completion studies of the internal carotid artery following carotid endarterectomy are recommended to ensure technical perfection of the repair. Transit time ultrasound flowmeter does not require trained technicians, requires less time than other completion studies such as duplex ultrasonography and contrast arteriography, and is noninvasive. Flowmetry was compared with duplex ultrasonography and contrast arteriography to determine if the relatively simpler flowmetry could replace these two more widely accepted completion studies in the intraoperative assessment of carotid endarterectomy. Comparative intraoperative assessment was performed in 116 carotid endarterectomies using all three techniques between December 1, 2000 and November 30, 2003. Eversion endarterectomy was performed in 51 cases and standard endarterectomy with prosthetic patching in 65 cases. Patients underwent completion flowmetry, duplex ultrasonography, and contrast arteriography studies of the exposed arteries, which were performed by vascular fellows or senior surgical residents under direct supervision of board-certified vascular surgeons. Duplex ultrasonography surveillance was performed 1 and 6 months postoperatively and annually thereafter. Mean follow-up was 18 months (range, 6-42 months). The combined ipsilateral stroke and death rate was 0%. The mean internal carotid artery flow using flowmetry was 249 mL/min (range, 60-750 mL/min). Five (4.3%) patients had flow < 100 mL/min as measured with flowmetry, but completion contrast arteriography and duplex ultrasonography were normal and none of the arteries were re-explored. One carotid endarterectomy was re-explored based on completion duplex ultrasonography that showed markedly elevated internal carotid artery peak systolic velocity (> 500 cm/sec); however, exploration was normal and completion flowmetry and contrast arteriography were normal. Duplex ultrasonography studies revealed internal carotid artery peak systolic velocities > 150 cm/sec in 15 patients, but flowmetry and contrast arteriography were normal in all 15 cases and none of the arteries were re-explored. There was no correlation between flow rates measured using flowmetry and peak systolic velocities measured using duplex ultrasonography. One abnormal contrast arteriogram showed an intimal flap that was revised, but duplex ultrasonography and flowmetry were normal. Severe recurrent internal carotid artery stenosis developed in 2 patients at 6 and 9 months, but all 3 completion intraoperative studies at the time of the original operation were normal. Based on these results, wide variability in flowmetry values limits its potential usefulness to detect non-flow-limiting lesions and replace contrast arteriography or duplex ultrasonography as an intraoperative carotid endarterectomy completion study. Duplex ultrasonography was also of limited to no value, whereas contrast arteriography rarely documented a lesion that required repair.     

Intraoperative ultrasonic imaging of the carotid artery during carotid endarterectomy

Intraoperative real-time B-mode ultrasonography was used to evaluate the technical results of 155 carotid endarterectomies in 143 patients. Technical defects created as a result of the endarterectomy were detected in 43 of the 155 endarterectomies (27.7%) and included intimal flaps (73% of defects); strictures (18%); and arterial kinks, residual plaque, and intraluminal thrombi (9% collectively). Eleven of the 43 endarterectomy sites (7% of all endarterectomies) were reentered to correct a defect; none of these patients had neurologic deficits, which suggests that reentering an endarterectomy and correcting a defect does not, in and of itself, lead to a higher incidence of stroke. The incidence of stroke in patients with normal results of intraoperative ultrasonography was 3.8%, whereas the incidence of perioperative stroke in those patients with insignificant and thus uncorrected defects was 3.3%; this suggests that intraoperative ultrasonography is sufficiently sensitive to detect defects that, when left uncorrected, do not lead to a higher than usual incidence of stroke. Because intraoperative ultrasonography is safe and highly sensitive, we believe it is the method of choice for assessing the technical results of carotid endarterectomy.     

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.     

Neurological evaluation by intraoperative wake-up during carotid endarterectomy under general anesthesia

Although general anesthesia allows relief from stressors such as pain, discomfort, or anxiety for patients undergoing carotid endarterectomy, neurologic assessment is less reliable than under local anesthesia. We describe a unique anesthetic management strategy for carotid endarterectomy patients incorporating the advantages of both general and local anesthesia. The technique allows thorough assessment of neurologic function during carotid cross-clamping by intraoperative wake-up, and guarantees airway management by tracheal intubation.     

Internal carotid artery flow volume measurement and other intraoperative duplex scanning parameters as predictors of stroke after carotid endarterectomy

PURPOSE: Intraoperative duplex scanning (IDS) after carotid endarterectomy (CEA) has been shown to reliably identify major defects either by significant changes in peak systolic velocities or by B-mode imaging. To evaluate whether IDS could also predict postoperative strokes in technically flawless CEAs, we analyzed several hemodynamic parameters and correlated them with patient outcome. METHODS: From March 2000 to February 2001, 226 consecutive primary CEAs were performed in 208 patients (120 men). Of these, 153 lesions were asymptomatic. General anesthesia and synthetic carotid artery patches were used routinely. Intraluminal shunts were used when internal carotid artery (ICA) back-pressures were <50 mm Hg (35% of cases). IDS consisted of B-mode and color-flow imaging and spectral analyses of the common, external, and internal carotid arteries. Volume flows were measured three times, and the mean flow rate was used for this study. RESULTS: The first set of data was analyzed when the twenty-ninth patient had the second immediate postoperative stroke. It was noted that the two patients who had postoperative strokes had mean ICA volume flows (MICAVF) of 48 mL/min and 85 mL/min. Only two additional patients had MICAVF <100 mL/min. The remaining 25 cases had MICAVF ranging from 102 to 299 mL/min, with a mean of 165 +/- 57 mL/min (+/-SD) (P <.02). Although there was a significant correlation between MICAVF and ICA peak systolic velocity (P <.01), the latter was not found to be a significant predictor of postoperative stroke. Moreover, end-diastolic velocities, resistive index, ICA diameter, and ICA back-pressure also did not correlate with neurologic events. These findings led us to change our protocol for patients with MICAVF <100 mL/min. This included a repeat set of volume flow measurements after 15 to 20 minutes, withholding the reversal of heparin, and the liberal use of completion arteriography. Of the following 197 CEAs, 26 (13%) were found to have MICAVF <100 mL/min (range 55 to 99 mL/min; mean 79 +/- 18 mL/min). Of these, five had arteriography that documented spasm of the intracranial portion of the ICA in four and a small-diameter ICA (<2 mm) in one. Except for the five cases, the remaining 21 cases had MICAVF >100 mL/min (range 105 to 158 mL/min, mean 127 +/- 20 mL/min [+/-SD]) on repeat study. Four patients with persistent ICA low flow (70 to 99 mL/min) were treated with postoperative anticoagulation. One of the last 197 patients had a stroke caused by hyperperfusion syndrome 2 weeks after operation. Overall, six of 226 cases (2.7%) required revision on the basis of abnormal B-mode imaging results or peak systolic velocities >150 cm/s. There were two common carotid artery flaps, two ICA stenoses, one ICA flap, and one localized thrombus. All six were successfully revised and had repeat normal IDS study results, and none of these patients had a postoperative stroke. CONCLUSIONS: IDS is helpful in identifying residual lesions or defects that may contribute to postoperative neurologic deficits. MICAVF <100 mL/min are suggestive of spasm that could lead to thrombus formation and stroke, particularly in the presence of synthetic patches. We suggest that heparin reversal should not be used unless ICA flow rates are >100 mL/min. ICA spasm is short lived in most patients undergoing CEA.     

Relationship between intraoperative color-flow duplex findings and early restenosis after carotid endarterectomy: A preliminary report

Purpose: This study was undertaken to examine the relationship between intraoperative color-flow duplex (CFD) findings and the development of restenosis in patients undergoing carotid endarterectomy (CEA).Methods: Seventy-eight patients (43 male and 35 female; mean age, 65 years) underwent 86 CEAs (eight staged bilateral) and intraoperative CFD during a 31-month period. Three patients (three CEAs, 3%) underwent both CFD and a completion arteriographic scan. Patients were observed in a postoperative protocol using CFD surveillance. The follow-up interval ranged from 6 to 24 months (average, 12 months).Results: After undergoing CEA, 10 patients (10 CEAs, 11%) had an abnormality detected by intraoperative CFD; one was confirmed with a completion arteriographic scan. These abnormalities consisted of elevated peak systolic velocities (PSV) with a mosaic color pattern suggesting turbulence seen in six CEAs, including one internal carotid artery (ICA) with abnormal hemodynamics and an unremarkable completion arteriogram. Intimal defects on B-mode were seen in another four CEAs. These carotid arteries were reexplored, defects (intimal flaps with platelet thrombus) were confirmed by direct examination, and all were repaired with or without a patch (six ICAs, three external carotid arteries, and one common carotid artery). No cerebrovascular events occurred in the perioperative period. No carotid restenosis (≥50% diameter reduction) was identified during follow-up of 43 patients (48 CEAs, 56%). Two patients had recurrent neurologic symptoms.Conclusion: Intraoperative CFD is an effective test for detecting flow abnormalities or intimal defects in patients undergoing CEA. Ensuring normal intraoperative hemodynamics after CEA may be a major factor associated with decreased incidence of perioperative cerebrovascular events and subsequent carotid artery restenosis. (J Vasc Surg 1996;24:588-96.)     

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.     

Clinical benefit of carotid endarterectomy based on duplex ultrasonography

Carotid endarterectomy has been shown to significantly reduce the risk of stroke caused by carotid artery stenosis in selected patients. Limiting the morbidity and costs of this process without increasing the risks should further improve the benefits of this procedure. Results were prospectively collected from 123 consecutive carotid endarterectomies performed at a community teaching hospital. All patients underwent duplex ultrasonography for preoperative evaluation. Catheter angiography was used on a selective basis. Preferential use of regional anesthetic and selective use of the intensive care unit were applied. The mortality, morbidity, complications, and costs were then compared for the group receiving only preoperative duplex ultrasonography with those undergoing catheter angiography preoperatively. Age, comorbid risk factors, indications for carotid endarterectomy, and incidence of stroke were similar in both patient groups. The rates of mortality, morbidity, and stroke for carotid endarterectomy were low (mortality 0%, morbidity 6.5%, stroke 0.8%). For preoperative evaluation all patients underwent duplex ultrasonography (100%) and 28 (23%) underwent preoperative catheter angiography in addition to duplex ultrasonography. The complication rate associated with catheter angiography was 6/28 (21%). Complications included groin hematoma (7%), pseudoaneurysm (3.6%), bradycardia (7%), and unstable angina (3.6%). Costs for duplex ultrasonography averaged 165 US dollars and additional costs incurred by the use of catheter angiography averaged 4,200 US dollars. Intraoperative assessment of the carotid endarterectomy site did not change based on the use of preoperative catheter angiography. Morbidity, mortality, and stroke rates were the same for the 2 groups. The preoperative use of duplex ultrasonography for the sole evaluation in carotid endarterectomy is well established. The use of preoperative catheter angiography is still preferred by a subset of surgeons. The use of catheter angiography is associated with significant morbidity and additional costs when compared to performing carotid endarterectomy based solely on preoperative duplex ultrasonography. The added costs and morbidity of angiography increase the societal cost of this procedure without significant clinical improvement in patient outcome.     

The outcome of external carotid endarterectomy during routine carotid endarterectomy

Purpose: This study is an analysis of the outcome of a common method of management of the external carotid artery (ECA) during routine carotid endarterectomy (CEA). Methods: Between 1986 and 1997, 1069 primary CEAs were performed with a combination of proximal eversion technique and blind distal endarterectomy on the ECA. Of these, 973 CEAs (91%) had 1 or more postoperative duplex scans that included the ECA. Both preoperative and early postoperative studies were performed on 313 of these CEAs. Intraoperative post-CEA continuous-wave Doppler scans identified low flow or occlusion of the ECA in 37 CEAs (4%). These ECAs were isolated and repaired. Results: The early post-CEA duplex scan velocities were 143 ± 81 cm/s (mean ± l standard deviation of the mean). In the first 6 months after the CEAs, 692 ECAs (72%) had <50% stenosis, 175 (18%) had 50% to 74% stenosis, 90 (9%) had ≥75% stenosis, and 9 (1%) were occluded. Of the 37 repaired ECAs, 20 (54%) had <50% stenosis, 10 (27%) had 50% to 74% stenosis, 5 (14%) had ≥75% stenosis, and 2 (5%) were occluded. The cumulative life-table ≥50% stenosis rate was 36% at 1 year, 40% at 3 years, 48% at 5 years, and 81% at 10 years. The cumulative ≥75% stenosis rate was 12% at 1 year, 12% at 3 years, 15% at 5 years, and 37% at 10 years. Preoperative studies showed <50% stenosis in 152 of the 313 ECAs (48%). In the early postoperative period, 102 of these ECAs (66%) had <50% stenosis, 35 (23%) had 50% to 74% stenosis, 13 (9%) had ≥75% stenosis, and 3 (2%) were occluded. Of the 161 ECAs with ≥50% preoperative stenosis, 66 (41%) had <50% stenosis in the first 6 months after CEA, 61 (38%) had 50% to 74% stenosis, 32 (20%) had ≥75% stenosis, and 2 (1%) were occluded. Conclusions: Combined proximal eversion technique and blind distal ECA endarterectomy during routine CEA gives poor and unacceptable early and late outcomes. The repair of severely obstructed or occluded ECA identified during surgery after CEA has a similarly poor outcome. The technique and management of the ECA during routine CEA needs further investigation and modification. (J Vasc Surg 1998;28:585-90.)     

Pitfalls during carotid endarterectomy

Summary It is estimated that between 1971 and 1987 the number of carotid endarterectomies has increased from 15,000 to over 85,000 per year. Unless the procedure can be performed safely with a combined morbidity and mortality which is below the yearly risk of stroke (5%) for patients with symptomatic carotid artery disease, one should reconsider this operation as a therapeutic option.We review our experience with 891 carotid endarterectomies performed between January 1979 and June 1987. There were 579 (65%) men and 312 (35%) women of ages from 34 to 82 (median 65); risk factors included diabetes mellitus 213 (14%), hypertension 603 (68%), and smoking 630 (70%). Clinical presentation consisted of transient ischemic attacks 506 (57%), cerebral infarction with minimal neurological residual 252 (28%), stroke in evolution 3 (0.3%) and, asymptomatic stenosis 130 (15%). All patients were operated on under endotracheal anesthesia with transoperative monitoring of intra-arterial pressure, central venous pressure and arterial blood gases. Thiopental (3–5 mg/kg) and lidocaine (1 mg/kg) were given for induction and at 15 minute intervals during carotid cross-clamping. Intraluminal shunts were used in 13 (2%). A conventional (open) endarterectomy was performed in 561 (63%) and a limited endarterectomy (closed) in 330 (37%). Complications included 11 (1%) deaths, 26 (3%) developed a major neurological deficit that persisted, 30 (3%) had perioperative TIA's which resolved completely. Of the patients with preoperative neurological deficits, 33 (4%) recovered. Therefore, at one month after surgery, 854 (96%) were either as well or better than preoperatively. Of 514 (58%) postoperative angiograms, 23 (5%) showed an internal carotid artery occlusion; six of them developed an immediate postoperative cerebral infarction and one of them died, Non-neurologic complications were: cardiac 43 (5%), peripheral nerve 33 (3%), and local wound problems 20 (2%).We believe a carotid endarterectomy can be performed safely when it is done with meticulous attention to detail and consistent surgical technique founded on frequent exposure to the procedure.