Duplex scanning alone before carotid endarterectomy: a 5-year experience

Carotid near-occlusion frequently has high peak systolic velocity on Doppler ultrasound

PURPOSE

Carotid near-occlusion is a tight atherosclerotic stenosis of the internal carotid artery (ICA) resulting in decrease in diameter of the vessel lumen distal to the stenosis. Near-occlusions can be classified as with or without full collapse, and may have high peak systolic velocity (PSV) across the stenosis, mimicking conventional > 50% carotid artery stenosis. We aimed to determine how frequently near-occlusions have high PSV in the stenosis and determine how accurately carotid Doppler ultrasound can distinguish high-velocity near-occlusion from conventional stenosis.

METHODS

Included patients had near-occlusion or conventional stenosis with carotid ultrasound and CT angiogram (CTA) performed within 30 days of each other. CTA examinations were analyzed by two blinded expert readers. Velocities in the internal and common carotid arteries were recorded. Mean velocity, pulsatility index, and ratios were calculated, giving 12 Doppler parameters for analysis.

RESULTS

Of 136 patients, 82 had conventional stenosis and 54 had near-occlusion on CTA. Of near-occlusions, 40 (74%) had high PSV (≥ 125 cm/s) across the stenosis. Ten Doppler parameters significantly differed between conventional stenosis and high-velocity near-occlusion groups. However, no parameter was highly sensitive and specific to separate the groups.

CONCLUSION

Near-occlusions frequently have high PSV across the stenosis, particularly those without full collapse. Carotid Doppler ultrasound does not seem able to distinguish conventional stenosis from high-velocity near-occlusion. These findings question the use of ultrasound alone for preoperative imaging evaluation.

Extracranial and Transcranial Color-Coded Sonography Reduce the Need for Angiography Prior to Carotid Endarterectomy

The growing need for carotid endarterectomy must be accompanied by safe and reliable methods of imaging the cerebral circulation. The authors used extracranial and tran scranial color-coded sonography to evaluate the cervical carotid arteries and the basal cerebral circulation in 76 patients prior to surgery, aiming to reduce the need for preop erative angiography. In 3 patients (proximal and distal carotid disease; subtotal occlusion) carotid ultrasound failed to define the nature and extent of stenosis adequately, and thus conventional angiography was performed. Transcranial imaging identified intracranial stenotic disease in 4 patients and interhemispheric collateral flow in 29 patients. All patients underwent carotid endarterectomy without any complications due to inadequate preoperative imaging. An ultrasound-based approach eliminated the need for angiography in the majority of patients with significant implications for risk reduction and financial expenditure.

Carotid Endarterectomy Based on Duplex Ultrasonography: A Safe Approach Associated with Long-term Stroke Prevention

To evaluate the short-term and long-term safety of carotid endarterectomy (CEA) based on duplex ultrasound without confirmatory diagnostic arteriography.

A 4-year retrospective review of CEA based on duplex ultrasound alone (n = 653) or with confirmatory arteriography (n = 118) was performed in 244 women and 458 men whose ages ranged from 39 to 92 years (mean, 70 years). Practice patterns, perioperative morbidity, and stroke rate (life-table analysis) of a community-based and university- based vascular surgical practice were analyzed and compared.

Surgical intervention based on duplex ultrasound was judged possible in 85% of the patients (community, 93%; university, 55%). Indications for arteriography included: testing completed prior to surgical consultation (44%), nonfocal extracranial carotid stenosis (23%), nonhemispheric symptoms (13%), and prior stroke (9%). This approach was safe (with a combined operative mortality and neurologic morbidity of 1.8%), asso ciated with long-term stroke prevention (a 95% stroke-free survival at 4 years), and yielded results similar to CEA with arteriography (operative morbidity, 2.6%; 91% stroke- free survival). The incidence and nature of late neurologic deficits were similar after CEA with and without arteriography. Twenty-three (4%) of the patients who underwent CEA based on duplex ultrasound developed late neurologic symptoms including 9 contralat eral and 4 ipsilateral strokes; and 4 ipsilateral and 4 contralateral transient ischemic attacks (TIAs). Cardiac embolism from atrial fibrillation accounted for 6 strokes, lacunar infarct associated with hypertension (3 strokes), intracranial atherosclerosis (3 strokes), and contralateral internal carotid artery (ICA) occlusion (1 stroke). Forty patients (6.8%) died predominantly from cardiac events. After CEA with arteriography 6 (5%) of the patients died. Six late strokes (4 contralateral, and 2 ipsilateral hemisphere) occurred as a result of progressive, untreated ICA stenosis (n = 3), and lacunar infarct (n = 3). Overall, 11% of the patients underwent contralateral CEA for progressive ICA stenosis.

CEA, based on duplex scanning, is safe and applicable for the majority of patients undergoing surgical evaluation. Short-term and long-term outcomes were similar to outcomes in patients having CEA based on diagnostic arteriography.

Correlation between Doppler velocities and duplex ultrasound carotid cross-sectional percent stenosis

RATIONALE AND OBJECTIVES

Cross-sectional imaging is being increasingly proposed as a suitable tool to characterize carotid plaques. The aim of this work was to correlate the Doppler velocity parameters with the cross-sectional percent stenosis (CPoS) of internal carotid artery (ICA) and to identify the cutoff values of these parameters in five progressive classes of stenosis area severity (ie, 40%-49%, 50%-59%, 60%-69%, 70%-79%, 80%-90%).

MATERIALS AND METHODS

High-quality scans from 90 patients (mean age, 74 ± 9 years) with 43%-90% ICA stenosis were analyzed. ICA peak-systolic (PSV) and end-diastolic (EDV) velocities were measured at maximum stenosis level. Total ICA area and residual lumen (RL) were measured to derive the CPoS. A simple physical model described by the equation Velocity = Flow rate/Area was considered. Effectively, the CPoS is expected to negatively correlate with the inverse of velocity parameters, assuming flow rate to be constant. Multiple stepwise regression analyses were used to investigate the relationships between velocity and echographic measures.

RESULTS

With CPoS as the dependent variable, the first significant regressor was the inverse ICA-EDV (r(2) = 0.64; P < .0001) followed by inverse ICA-PSV (r(2) = 0.43; P < .0001). ICA-EDV mean values throughout five progressive classes of stenosis were: 28 cm/second for 40%-49% stenosis, 35 cm/second for 50%-59%, 43 cm/second for 60%-69%, 69 cm/second for 70%-79%. and 103 cm/second for 80%-90%. ICA-PSV mean values were: 97 cm/second for 40%-49%, 110 cm/second for 50%-59%, 136 cm/second for 60%-69%, 224 cm/second for 70%-79%, and 286 cm/second for 80%-90%.

CONCLUSION

ICA-EDV is the parameter that better correlates with CPoS. Nevertheless, ICA-PSV maintained a highly significant correlation with CPoS. Moreover, the categorization of Doppler parameters in five progressive classes of severity of stenosis could provide physicians with an easily accessible tool in clinical practice, complementary to the morphological evaluation of cross-sectional stenosis.

Critical review of non- or minimally invasive methods (duplex ultrasonography, MR- and CT-angiography) for evaluating stenosis of the proximal internal carotid artery

OBJECTIVE

to assess the performance of non- or minimally invasive methods (duplex ultrasonography, MR- and CT-angiography) in measuring stenosis of the proximal internal carotid prior to endarterectomy without preoperative intra-arterial digital subtraction angiography (DSA).

METHODS

systematic review of the literature (five databases, 1990 to February 2001). The value of each imaging technique was studied through its reproducibility and its sensitivity/specificity compared to DSA.

RESULTS

sensitivity exceeded 80% and specificity 90% in over two-thirds of the methodologically sound studies, regardless of technique, although direct comparisons between results had to be avoided since the findings originated from different populations. The main drawback of duplex ultrasonography is its levels of reproducibility. In contrast, only a few studies have addressed the reproducibility of MR- and CT-angiography. When the results of duplex and MR-angiography agree, the combination use of these two techniques provides a better diagnosis than either technique taken alone.

CONCLUSIONS

all three techniques appear suitable for measuring stenosis of the proximal internal carotid when compared to DSA.

Results of carotid endarterectomy performed with preoperative duplex ultrasound assessment alone

Contrast injection cerebral angiography has been considered for several decades the "gold-standard" technique for diagnosis and operative planning of carotid disease. More recently, however, an increasing number of institutions are using duplex ultrasound as the single independent preoperative test. The objective of this investigation was to evaluate the impact of the utilization of duplex ultrasonography as the only preoperative test on the outcome of the procedure. Between 1993 and 1996, the authors performed 1,149 carotid procedures. Duplex ultrasound as the only preoperative test was employed with increasing frequency in a total of 728 cases. In 1995 and 1996, a cerebral arteriogram was performed only if duplex ultrasound was technically inadequate or questionable or showed an atypical pattern of disease. During the 4 years analyzed in this study, the number of the procedures increased from 165 in 1993 to 412 in 1996. The thirty-day mortality rate was 0.43%, and neurologic morbidity was 1.65%. According to the year in which the procedure was performed, the mortality/morbidity rates were 1.2/2.4 in 1993, 0.52/2.08 in 1994, 0.26/1.57 in 1995, and 0.24/1.21 in 1996. Indication to perform an arteriogram became very selective in 1995. Regardless of these changes in the diagnostic work-up, some degree of reduction in both 30-day mortality and neurologic morbidity was recorded. Considering a cost of 724 European Currency Units (ECU) per arteriogram, 527,072 ECU were saved in this period. In the last 4 years, duplex ultrasound has replaced arteriography as the first-choice technique for preoperative assessment of carotid disease at the authors' institution. There was definitely no detrimental effect on the clinical results that, on the contrary, improved during the same period. This policy has allowed a significant reduction in the cost of the procedure and has most likely prevented several arteriography-related complications. The authors recommend this policy to all institutions in which accurate duplex ultrasound is available.

Carotid endarterectomy without angiography: a prospective randomised pilot study

OBJECTIVES

to determine whether duplex ultrasonography alone is an adequate examination prior to carotid endarterectomy.

DESIGN

prospective, randomised, single centre study.

MATERIAL AND METHODS

all patients with carotid bifurcation stenosis greater than 70% - based on duplex scanning - were randomised to arteriography followed by carotid surgery (Group A n=96) or carotid surgery alone (Group B n=90). Study endpoints were neurological complications or death occurring between the day of randomisation and until 30 days after surgery.

RESULTS

major neurological complications of death in 1 (1%) vs 3 (3.3%) patients in group A and B, respectively (n.s.). Minor neurological complications (only TIA) were observed in 0 and 3 (3.3%) patients, respectively.

CONCLUSIONS

complication rates were low in both groups and within the generally accepted rate after carotid surgery in asymptomatic and symptomatic patients.

Effect of contralateral disease on duplex measurements of internal carotid artery stenosis

BACKGROUND

Duplex ultrasonography is increasingly used as the sole method of imaging before carotid endarterectomy. This study investigated the measured degree of stenosis in the contralateral carotid artery before and after operation.

METHODS

Duplex-derived peak systolic velocity (PSV), end-diastolic velocity (EDV) and internal carotid artery/common carotid artery (ICA/CCA) velocity ratios were measured in the contralateral unoperated ICA before 131 consecutive unilateral endarterectomies and compared with preoperative angiographic findings. Three months later duplex scans were repeated to assess whether there had been any alteration in the severity of the stenosis in the contralateral unoperated artery.

RESULTS

Bilateral ICA disease (greater than 50 per cent stenosis) was present in 50 patients (38 per cent). Three months after operation, ultrasonography of the 105 unoperated, patent, contralateral arteries showed a decrease in mean(s.d.) PSV (1.21(0. 83) versus 1.07(0.69) m/s; P < 0.01) and EDV (0.41(0.29) versus 0. 35(0.24) m/s; P < 0.01). This resulted in 14 (42 per cent) of 33 patients with contralateral disease being downgraded to a less severe category of stenosis. Use of the ICA/CCA velocity ratio prevented overestimation in eight of the 14 patients, while preoperative angiography correctly classified 13 of the 14 patients.

CONCLUSION

Bilateral carotid artery disease can cause overestimation of the severity of stenosis by duplex ultrasonography if absolute velocity is used as the main criterion.

Carotid endarterectomy without angiography: can clinical evaluation and duplex ultrasonographic scanning alone replace traditional arteriography for carotid surgery workup? A prospective study

BACKGROUND

The aim of this study was to determine whether clinical evaluation and duplex ultrasonography (DUS) alone can replace contrast cerebral arteriography (CA) for the detection of patients suitable for surgery at our institution.

METHODS

During an 18-month period, 100 patients underwent DUS and CA during evaluation for carotid endarterectomy (CEA). All patients were studied prospectively; in each case an initial decision for or against CEA on the basis of DUS evaluation of the internal carotid arteries (ICAs) was subsequently compared with the surgeon's final management plan after CA. Of the 200 ICAs evaluated, 113 were considered for CEA but 14 were excluded from the study because the patient could not be evaluated before and after CA. This left 99 ICAs (86 patients) available for comparative analysis.

RESULTS

The outcome of the 2 diagnostic modalities was perfectly consistent in 95.3% of the ICAs (kappa = 0.969). The clinical management decision was altered by the CA findings in only 2 cases (2%). Of the 99 ICAs considered suitable, 97 underwent CEA. No arteriographic complications occurred among the 100 patients undergoing CA. The perioperative stroke risk and mortality rates were 0%.

CONCLUSIONS

Ninety-eight percent of the ICAs considered for surgery would have received appropriate clinical treatment on the strength of the patients' neurologic history and the outcome of DUS alone. Our results indicate that DUS is sufficient to establish the need for surgery in symptomatic and asymptomatic patients being considered for CEA and can replace CA in most clinical circumstances.

Duplex scanning and CT angiography in the diagnosis of carotid artery occlusion: a prospective study

OBJECTIVES

Differentiating total occlusion from tight stenosis of the internal carotid artery is crucial with regard to treatment and prognosis. At our institution, the diagnosis of carotid stenosis is based on duplex scanning. In cases of occlusion, duplex is not reliable, and angiography is performed, thereby increasing morbidity. We tried to determine whether a combination of duplex scanning and CT angiography (CTA) can replace angiography in the diagnosis of carotid occlusion.

DESIGN

Prospective study.

MATERIALS AND METHODS

From 1995 to 1997, 148 patients were diagnosed as having carotid occlusion by duplex scanning. CTA was performed on all patients. Forty-four patients underwent angiography and 10 patients were surgically explored. Both procedures were considered "gold standard" for the diagnosis of occlusion.

RESULTS

Arteries found to be occluded by both CTA and duplex scan were confirmed as occluded by angiography or operation in 95% of the cases (42/44). Arteries found to be occluded by duplex but patent by CTA were confirmed as patent in 100% of cases (10/10). CTA has a significantly higher positive predicting value for diagnosing occlusion than duplex scan (95% vs. 77%, p value < 0.01).

CONCLUSIONS

Combination of duplex scanning and CTA is safe and accurate in the diagnosis of carotid occlusion and can replace angiography in most cases, thereby reducing morbidity.

Can duplex ultrasonography select appropriate patients for carotid endarterectomy?

OBJECTIVES

This study investigated the reliability of carotid duplex ultrasound (DUS) to identify appropriate candidates for carotid endarterectomy (CEA) according to a panel of vascular specialists.

DESIGN

Prospective study.

MATERIAL

102 patients with 145 carotid bifurcation stenosis or occlusions.

METHODS

All patients who required a carotid angiogram were evaluated using DUS followed by carotid angiography. A blinded panel of four vascular specialists individually decided whether CEA would be appropriate for each patient based on pre-angiographic information. Angiograms were then shown to panelists to see if their management decision was altered by the angiogram.

RESULTS

For stenosis > or = 80% on DUS (n = 60), panelists unanimously agreed on CEA without angiography in 57 lesions. In 50 lesions (87.7%), angiography showed > or = 70% stenosis and the management plan remained unchanged. For the other seven lesions, intracranial aneurysms (n = 2), tandem intracranial lesion (n = 1), unsuspected proximal common carotid lesion (n = 1), a 40% stenotic lesion (n = 1), and high carotid bifurcations (n = 2) were seen. In lesions with 50-79% stenosis on DUS (n = 66), none of the panelists recommended CEA without prior angiography. Eighteen (27%) of these lesions were > or = 70% stenosed on angiogram. Complications of angiograms included one stroke, one haematoma, and one severe allergic reaction.

CONCLUSION

Carotid duplex ultrasonography without angiography can reliably select lesions appropriate for surgery only when critical stenosis > or = 80% is chosen. Routine angiography is recommended for carotid stenosis of 50-79% when CEA is considered.

Preoperative testing before carotid endarterectomy: a survey of vascular surgeons' attitudes

Traditional surgical practice and published consensus statements from major vascular surgery specialty societies have considered contrast arteriography to be a routine part of the diagnostic evaluation prior to carotid endarterectomy (CEA). However, some surgeons now omit routine preoperative arteriography if a technically adequate carotid duplex scan is performed and indications for CEA are clear. To better establish current practice patterns and to characterize vascular surgeons' opinions about the role of preoperative arteriography, the Peripheral Vascular Surgery Society membership was surveyed by mail. Eighty-six percent of the members responded (430 of 502). Ninety-three percent of all patients considered for CEA are evaluated with duplex scanning; 82% with arteriography. While the majority of surgeons typically obtain both a duplex scan and an arteriogram, 70% have performed CEA without a preoperative arteriogram. Brain imaging studies (CT or MRI) are obtained in 26% and MR angiograms in 10% of cases. Seventy-five percent of the surgeons agreed with the statement that CEA without preoperative arteriography is an acceptable practice if appropriate indications for surgery are present. Furthermore, one third believed that CEA without a preoperative arteriogram is generally acceptable (acceptable more than half the time). Respondents were stratified by surgical experience time in practice and practice type. No significant differences in responses were found, suggesting the acceptance of CEA without preoperative arteriography is broad-based. This survey demonstrates changing attitudes among practicing vascular surgeons regarding the necessity for routine arteriography prior to CEA. Carotid endarterectomy on the basis of duplex scanning and clinical assessment should be considered an accepted alternative.

The practice of carotid endarterectomy in Australasia

BACKGROUND

Carotid endarterectomy (CEA) is a frequently performed surgical procedure and there are variations in the preoperative, operative and postoperative management related to this operation.

METHODS

Questionnaires were sent to all 191 members of the Division of Vascular Surgery, Royal Australasian College of Surgeons, and the Australasian Chapter of the International Society of Cardiovascular Surgery.

RESULTS

The questionnaire was returned by 179 surgeons (94%). One hundred and fifty-nine were vascular surgeons, of whom 139 perform CEA. Most surgeons reported performing more CEA than 5 years previously. Surgery for asymptomatic carotid stenosis was performed by 78% of surgeons at the time of the survey. Routine carotid angiography is performed pre-operatively for symptomatic patients by 61% of surgeons and for asymptomatic patients by 56%. Intra-operative shunting is used routinely by 37% of surgeons, selectively by 58% and never by 5%. Arteriotomy patch closure is performed routinely by 16%, usually by 30%, rarely by 52% and never by 3%. The favoured patch material is Dacron 39%, PTFE 19%, ankle long saphenous vein (LSV) 22%, thigh LSV 18% or other materials 2%. Compared to their practice 5 years previously, arterial patch closure is used more often by 42% of surgeons, the same by 51% and less by 7%. Postoperatively, patients are nursed mainly in intensive care (34%) or a high-dependency unit (33%).

CONCLUSIONS

The practice of CEA by Australasian vascular surgeons reflects the recent trends reported in the world literature. Most Australasian surgeons perform CEA for asymptomatic disease. Forty per cent are performing CEA on the basis of duplex scanning alone. There is a trend towards increased use of patch closure. Most patients are managed in intensive care or high-dependency units.

Cost-efficient carotid surgery: a comprehensive evaluation

PURPOSE

This study was performed to determine whether comprehensive cost-cutting strategies adversely affect the outcome in patients undergoing carotid endarterectomy.

METHODS

From December 1994 to December 1995, 237 consecutive patients undergoing 260 carotid endarterectomies were prospectively studied. The following variables were assessed: carotid arteriography, preoperative laboratory tests, electrocardiograms and chest x-ray films, use of carotid shunts during operation, use of pathology department, intensive care, oxygen therapy, telemetry, and hospital stay. In addition, complications were tabulated.

RESULTS

Previously, all variables evaluated were routinely ordered. Subsequent to initiating the cost-containment strategies, the following results were achieved: arteriography in 52 (22%) of 237 patients, preoperative complete blood cell count and SMA-7 in 161 (62%) of 260 cases, preoperative electrocardiograms in 185 (71%) of 260 cases, preoperative chest x-ray films in 190 (73%) of 260 cases, carotid shunts in 83 (32%) of 260 cases, disease in no cases (0%), intensive care in 29 (11%) of 260 cases, oxygen therapy in 34 (13%) of 260 cases, telemetry in 17 (7%) of 260 cases, and hospital stay was decreased from an average of 2.6 to 1.3 days. Total savings based on average hospital and physician charges was $2.3 million. Complications included four strokes, one myocardial infarction, and no deaths. No patient required readmission. No recurrent or new neurologic or cardiac findings were identified clinically in follow-up at 1 and 4 weeks after surgery.

CONCLUSIONS

The results clearly demonstrate that comprehensive cost-cutting strategies can reduce charges significantly while maintaining patient safety.

Accuracy of duplex sonography before carotid endarterectomy--a comparison with angiography

OBJECTIVES

The aim of this prospective study was to contribute to the evaluation of the reliability of Duplex sonography (DS) before carotid endarterectomy (CEA).

DESIGN

The study was performed prospectively in a university hospital setting.

METHODS

Eighty-one consecutive patients aged 49-83 years were examined with DS and carotid angiography (CAG) before CEA. The results of the DS were judged as either confident, or CAG was assessed to be necessary preoperatively. The results from the DS and the CAG were then compared.

RESULTS

DS was judged as confident in 148 of the 162 arteries examined. In none of these 148 arteries did CAG change patient management in any way, and the agreement between DS and CAG was good. In the remaining 14 arteries CAG was judged necessary, in 11 arteries because DS assessed the internal carotid artery (ICA) as occluded, which was confirmed by CAG in 10 arteries. In three arteries the reason was poor quality of the DS, however these three arteries were correctly assessed as severely diseased.

CONCLUSIONS

This study confirms that DS alone is sufficient in the preoperative evaluation before CEA, provided that CAG is performed whenever DS shows occlusion of the ICA, or when the quality of the DS is poor.

The changing face of carotid endarterectomy

PURPOSE

The economic milieu and improvements in care have altered the diagnostic and therapeutic algorithm of the patient with carotid stenosis. This study analyzes the efficacy and safety of these changes.

METHODS

The records of patients who underwent 320 consecutive carotid endarterectomies performed by three surgeons at our institution from 1990 to 1994 were reviewed retrospectively. Use of diagnostic angiography, use of carotid duplex ultrasound, length of hospital stay, postanesthesia recovery observation, intensive care unit (ICU) observation, complications, and hospital charges were analyzed.

RESULTS

The average length of hospital stay decreased from 6.18 days to 2.00 days (p < or = 0.001). The day of discharge decreased from 3.10 days to 1.24 days after surgery (p < or = 0.01). By 1993, 68% were discharged by the first day after surgery, increasing to 73% by 1994. From 1990 to 1992, average postoperative ICU observation time fluctuated between 18 and 25 hours; this time decreased to 12.2 hours by 1994. In 1993, only 12.5% of patients were admitted to the ICU, down from 94.8% in 1990; by 1994, only 7.3% were admitted to the ICU (p < or = 0.001). Postanesthesia recovery observation time decreased from 3.77 hours to 1.63 hours during this time (p < or = 0.04). With regard to preoperative diagnosis, angiography was performed in 93.1% of patients in 1990; by 1994, only 32.8% underwent this procedure (p < or = 0.0001). Average hospital charges decreased significantly (1990, $14,378; 1994, $10,436) with these modifications in patient care (p < or = 0.001). The complication rate reflected no significant changes over the course of the study. There were six incidences of cerebrovascular accident (6/320, 1.9%), including one death. There were four incidences of transient ischemic attack (4/320, 1.3%), with no significant differences noted from year to year.

CONCLUSIONS

This study confirms the changing nature of carotid endarterectomy and documents that these changes have not adversely affected the safety of the operation.

Carotid endarterectomy--when to do it, how to do it?

With the completion of the major carotid endarterectomy trials the indications for this procedure can be defined. The procedure, if done by experienced teams, has been shown to improve the chance of stroke free survival in symptomatic and asymptomatic patients with a high-grade stenosis of the internal carotid artery. In asymptomatic patients the risk reduction gained by prophylactic carotid endarterectomy may be small in relation to the risk of coincident factors particularly coronary artery disease. The benefit gained by carotid endarterectomy depends closely on the risk of the procedure itself, and a single little flaw during the management can annulate the benefit of the operation in asymptomatic patients. There are still considerable controversies with regard to peri-operative management and surgical technique, e.g., the necessity of routine pre-operative arteriography has recently been questioned. Quality control programmes become a requirement with the publication of performance standards for carotid endarterectomy. According to a consensus of the American Heart Association, the surgical morbidity/mortality must be less than 6% for symptomatic carotid lesions and less than 3% for asymptomatic lesions. The present review discusses the steps of the pre-operative work-up, the procedure itself and the post-operative management with the aim to identify accepted safety standards as well as areas of uncertainty.

Short-stay carotid endarterectomy is safe and cost-effective

BACKGROUND

Carotid endarterectomy (CEA) is conventionally performed following a contrast arteriogram, under general anesthesia, and with postoperative admission to an intensive care unit (ICU). We investigated whether any of these traditional adjuncts to CEA is necessary.

PATIENTS AND METHODS

Eighteen consecutive patients had CEA performed according to a protocol of duplex scanning only, operation under regional anesthesia, and admission to the ICU only in cases of a proven need for services unique to the ICU (group I). Utilization of preoperative arteriography, admission to the ICU, postoperative complications, total hospital length of stay, and hospital charges were calculated for this group and results were compared with a group of 178 patients undergoing conventional CEA (arteriography, general anesthesia, routine ICU admission) during the same period (group II).

RESULTS

In group I, 1 patient (6%) underwent preoperative arteriography and 4 patients (22%) were admitted to the ICU after CEA. Most group II patients (114 of 178, or 64%) underwent preoperative arteriography and virtually all (175 of 178, or 98%) were admitted to the ICU. Compared with group II, the average hospital length of stay for group I was significantly shorter (1.3 +/- 0.1 versus 3.1 +/- 0.3 days, P = 0.03) and hospital charges were significantly reduced ($5,861 +/- 229 versus $11,140 +/- 729, P = 0.02).

CONCLUSIONS

This pilot study suggests that CEA can be safely performed without routine preoperative carotid arteriography; that routine ICU admission is unnecessary for the majority of cases; and that elimination of routine arteriography and ICU admission can reduce hospital charges for CEA by nearly one half.

Colour duplex scanning versus angiography: a retrospective assessment of carotid stenosis

A retrospective study was performed to investigate the reliability of colour duplex scanning as a screening method in detecting carotid artery disease. The results of this technique and digital subtraction arteriography of 100 carotid bifurcations in 50 patients undergoing carotid endarterectomy were compared. In accordance with suggested standard reports dealing with cerebrovascular disease, the diameter reduction was classified in one of five categories: < 20%, 20-59%, 60-79%, 80-99% and total occlusion. In 78% the gradings determined using digital subtraction arteriography and duplex scanning correlated perfectly, and in 99% of the studied bifurcations the difference was not more than one grade. The sensitivity and specificity of colour duplex scanning in detecting a stenosis with a diameter reduction of more than 60% was 98% and 87.7%, respectively. The best non-invasive method to identify carotid bifurcation disease is duplex scanning. Although the role of duplex scanning as an alternative to angiography is currently evolving, the authors still advocate carotid angiography when surgery is considered.

Comparison of magnetic resonance angiography, duplex ultrasound, and digital subtraction angiography in assessment of extracranial internal carotid artery stenosis

The results of a prospective study comparing ultrasound, intra-arterial digital subtraction angiography, and magnetic resonance angiography in the assessment of the degree of extracranial internal carotid artery stenosis are reported in patients with symptoms of recent carotid territory ischaemia. A total of 70 patients and 137 vessels were examined by all three techniques. The results obtained by each technique were reported blind. The mean difference (SD) for the comparison of magnetic resonance angiography and digital subtraction angiography was -0.7 (14)%, for ultrasound and digital subtraction angiography 3.1 (15)%, and for magnetic resonance angiography and ultrasound -3.8 (15)%. The level of agreement was greater for the more tightly stenosed vessels. With the assumption that the results of the digital subtraction angiogram reflect the true situation, the sensitivity and specificity in the detection of > or = 30% stenoses were 93% and 82% with ultrasound and 89% and 82% with magnetic resonance angiography; for stenoses > or = 70% 93% and 92% with ultrasound and 90% and 95% with magnetic resonance angiography; and for stenoses of 70-99% 89% and 93% with ultrasound and 86% and 93% with magnetic resonance angiography. For occlusion the values were 93% and 99% with ultrasound and 80% and 99% with magnetic resonance angiography. Increased sensitivity and specificity were obtained when analysis was confined to those vessels in which ultrasound and magnetic resonance angiography were in agreement over classification. It is thus possible to accurately categorize the degree of stenosis of the extracranial internal carotid artery from a combination of ultrasound and magnetic resonance angiography. The adoption of this combination for the investigation of patients before carotid endarterectomy removes the risk associated with conventional angiography and represents an important advance in the management of carotid stenosis.

Magnetic resonance angiography or IADSA for diagnosis of carotid pseudo occlusion?

Accurate diagnosis of internal carotid artery (ICA) occlusion is essential in the investigation of carotid disease yet may be difficult using Duplex. Traditionally contrast arteriography has been used to confirm the diagnosis despite its cost and potential dangers. Twenty-one patients with 23 ICA occlusions were evaluated by a 3-dimensional time of flight magnetic resonance angiography (MRA) technique. The cervical carotids and circle of Willis were imaged during the MRA examination which lasted 30 minutes. Confirmatory conventional angiography was performed in all patients. Using angiography as the gold standard, all occlusions were correctly diagnosed by MRA and 22 of 23 occlusions correctly diagnosed by Duplex. There was good agreement between MRA and angiography for all 42 ICAs imaged (Kappa statistic 0.83). Diagnosis of internal carotid artery occlusion is critical as it determines the need for operation. In this situation MRA provides a useful non-invasive complement to Duplex. A combination of non-invasive studies may enable arteriography to be rejected with greater confidence in this high risk group.

The diagnostic accuracy of duplex ultrasonography for evaluating carotid bifurcation

BACKGROUND

In many medical centers the standard preoperative study for patients undergoing carotid endarterectomy is four-vessel carotid arteriography, but duplex scanning of the carotid bifurcation is also reported to be highly accurate for detecting stenotic or occluded carotid arteries.

METHODS

The diagnostic accuracy of duplex ultrasonography was evaluated in a study of 774 carotid bifurcations, in 400 patients comparing the degree of predicted internal carotid artery (ICA) stenosis found using that technique, with that found by contrast arteriography. Agreement between the predicted degree of ICA stenosis and the arteriographic measurement was evaluated using the Spearman rank order correlation. Accuracy statistics for duplex scanning as a diagnostic modality were assessed using 2 x 2 tables.

RESULTS

The Spearman rank order correlation coefficient was 0.74 (P = 0) for the symptomatic group, 0.65 (P = 0) for the asymptomatic group, and 0.68 (P = 0) for the total group. The accuracy of duplex ultrasonography for detecting all grades of ICA stenosis ranged from 80% to 97%.

CONCLUSIONS

Duplex ultrasonography of the carotid bifurcation is a reliable diagnostic tool and can be used as the sole preoperative study for selected patients with extracranial cerebrovascular disease. Our current algorithm is discussed in conjunction with a critical analysis of this large database.

Carotid endarterectomy without arteriography

Arteriography has been considered the "gold standard" for evaluation of the cerebrovascular circulation prior to carotid endarterectomy. However, arteriography is associated with a neurologic complication rate of up to 12% in certain high-risk groups. Previous studies have shown that the duplex scanner has greater sensitivity than arteriography when both are correlated to the surgical specimen. From January 1986 to December 1991 a total of 174 carotid endarterectomies were performed in 152 patients, of which 61% were symptomatic. A total of 110 carotid endarterectomies in 92 patients were performed without the use of arteriography. Of the 64 patients in whom arteriograms were obtained, 33 were made at consultation and the others for various indications. Operative findings confirmed the duplex scan findings in all cases. A total of 91% of patients had intraoperative completion arteriograms. Of the 55 patients who also had intracranial views taken, two had a 50% siphon stenosis and one patient had a small intracranial aneurysm. None of these findings would have changed our management. The overall neurologic complication rate was one (0.66%) death due to stroke and four (2.6%) patients with transient ischemic attacks. Carotid endarterectomy can be safely performed without preoperative arteriography based on a detailed history and physical examination that includes bilateral upper extremity blood pressures and a duplex scan performed by a validated laboratory.

Duplex ultrasound in patients with suspected aorto-iliac occlusive disease

Duplex ultrasound scanning was used to localise and classify aorto-iliac occlusive disease. The study included 76 consecutive examinations of 73 patients with signs suggestive of proximal occlusive disease either by history or from traditional non-invasive laboratory investigation. Duplex ultrasound scanning indicated the presence of significant proximal occlusive disease in 70/101 limbs with suspected aorto-iliac disease. In total, 383/393 proximal arterial segments were assessed. A complete evaluation of the aorto-iliac region was possible in 91% of the patients. Duplex scanning was superior to oscillometric amplitude measurements and to CW Doppler examination, especially in patients with concomitant disease of the proximal superficial and deep femoral arteries. Duplex classification of stenoses correlated well with angiographic results obtained in 60 limbs with exact agreement in 194/211 (92%) arterial segments. Three of the patients with disparity between ultrasonography and angiography were investigated with intraarterial pressure measurements demonstrating that these lesions were underestimated by angiography. We conclude that Duplex ultrasound is feasible and accurate in detecting and grading lesions in the aorto-iliac region. This method provides important clinically useful haemodynamic information non-invasively in patients with suspected aorto-iliac occlusive disease.