Carotid endarterectomy in the elderly: risk factors, intraoperative carotid hemodynamics and short-term complications: a UK tertiary center retrospective analysis.

This retrospective analysis aims to demonstrate the safety of carotid endarterectomy (CE) in patients >75 years with particular attention paid to intraoperative hemodynamics. Four hundred and ninety-six consecutive patients with >70% symptomatic and asymptomatic stenosis who underwent CE were prospectively assessed and divided into those <75 years (n = 408; mean 64 years) and those >75 years (n = 88; mean 78 years). Associated risk factors, hemodynamic parameters, surgical techniques and 30-day perioperative complications were compared. Carotid artery stump pressures of <25 mmHg (13 versus 29%) and middle cerebral artery velocities of <20 cm/sec (46 versus 29%) were more common in those >75 years (P = 0.0001 and P <0.005, respectively). However, there was no difference in the frequency of intraluminal shunt (34% in both groups) or synthetic patch usage (primary patching: 12.5%, older group versus 11%, younger group; secondary patching: 34% in both groups), and no difference in the combined 30-day stroke and death rates (3.4%, >75 years versus 1.1%, <75 years; P = 0.425). CE in this cohort of patients >75 years was not associated with increased morbidity or mortality. Altered intraoperative hemodynamics were not associated with increased use of shunting or patching. This analysis supports CE as a safe procedure in the elderly.

Restenosis after carotid endarterectomy.

Multiple randomised trials over the last decade for both symptomatic and asymptomatic carotid stenosis have proven the efficacy of carotid endarterectomy (CE) in reducing the risk of stroke. The long-term patency of the carotid artery after CE is an important factor in the success of the operation. The incidence of recurrent carotid stenosis (excluding residual lesions) ranges from 1 to 37% with only 0-8% of patients having restenosis-related symptoms (1). Generally, recurrent carotid stenosis is attributed to myointimal hyperplasia during the early postoperative period (within 3 years) or recurrent atherosclerosis thereafter. The management of recurrent carotid stenosis after CE remains a dilemma. It is generally accepted that operation for significant recurrent carotid stenosis is indicated for symptomatic patients, and several authors also recommend CE for >80% asymptomatic recurrent stenosis. Treatment of recurrent carotid stenosis involves repeat endarterectomy with patch angioplasty, although more recently endovascular techniques have been used.

Sequential cohort study of Dacron patch closure following carotid endarterectomy.

BACKGROUND: Carotid endarterectomy reduces the risk of stroke and death in patients with severe carotid artery stenosis. This study examined whether the technique used to close the arteriotomy influenced the rate of perioperative transient ischaemic attack (TIA), stroke or death. METHODS: A cohort of 236 patients undergoing carotid endarterectomy at a single centre was studied; 117 patients had primary closure of the arteriotomy and 119 patients in a sequential series had closure with a Dacron patch. A standard endarterectomy with completion intraoperative duplex imaging and digital subtraction angiography was used throughout. RESULTS: Patch closure was associated with a significant reduction in the 30-day combined death, stroke and TIA rate: 10.3 per cent for primary closure versus 2.5 per cent for patch closure (P = 0.017). The risk of any cerebral event (stroke or TIA) was also significantly reduced (7.7 versus 1.7 per cent; P = 0.033). Residual stenosis on completion angiography was more common after primary closure (24.6 versus 7.4 per cent; P = 0.003). CONCLUSION: Dacron patch closure had a higher technical success rate on completion imaging and was associated with a significant reduction in the risk of perioperative stroke, TIA and death.

Correlation of intra-operative duplex findings during carotid endarterectomy with neurological events and recurrent stenosis at one year.

OBJECTIVES: Carotid endarterectomy has been used to treat both asymptomatic and symptomatic disease and this has meant that recurrent stenosis and its effect on late stroke risk have become increasingly important. In this study we compared anatomical defects and residual stenosis identified intra-operatively with recurrent stenosis and new symptoms developing in the first year after surgery. DESIGN, MATERIALS & METHODS: Two hundred and forty-four consecutive patients undergoing carotid endarterectomy were studied prospectively. Residual anatomical defects were noted; residual stenosis was defined by intra-operative duplex ultrasound as >50%. New stenoses and clinical events during the one-year surveillance period were documented. RESULTS: There was an increased incidence of recurrent stenosis at one year in vessels with residual stenoses (p<0.001) and in vessels containing a residual anatomical defect (p=0.037). There was no significant difference in recurrent stenosis rate with respect to closure (primary or patch) or seniority of surgeon but recurrent stenosis was increased in females (p=0.026). The majority (70%) of restenotic lesions were localised to the origin of the internal carotid artery. The late stroke rate was 0.9% and was not related to recurrent stenosis or symptoms. CONCLUSIONS: Residual stenosis and intra-luminal defects at completion increase the recurrent stenosis rate at one year. The aetiology of recurrent stenosis is multi-factorial and further studies are required to determine whether it is justified to modify the criteria for re-exploration with a view to reducing recurrent stenosis.

Value of intraoperative duplex imaging during supervised carotid endarterectomy.

BACKGROUND: For overall benefit, carotid endarterectomy requires low perioperative morbidity and mortality rates. Carotid thrombosis is usually secondary to technical error, which may be related to the experience of the operator. In this retrospective study the clinical and technical outcome of carotid endarterectomies performed by one consultant and five trainees were compared. METHODS: Some 149 patients underwent carotid endarterectomy; 89 were operated on by the consultant and 60 by trainees. Intraoperative duplex imaging of the carotid repair was performed before wound closure, and re-exploration was carried out when there was a residual severe stenosis associated with an intimal flap. RESULTS: There was no significant difference in clinical outcome between operations done by consultant or trainees. There was a significant increase in the number of stenoses, kinks and flaps in carotid endarterectomies performed by trainees compared with those of the consultant both before (chi2 = 12.0, 1 d.f., P < 0.001) and after (chi2 = 10.1, 1 d.f., P < 0.001) correction. CONCLUSION: Intraoperative duplex imaging may facilitate training by providing an objective assessment of the quality of the operation.

Cost-effective carotid endarterectomy.

BACKGROUND: Although carotid endarterectomy is increasing in the UK, there is evidence that the procedure is still underused. Methods of reducing cost in a single vascular unit have been assessed using a continuous audit including outcome measures. METHODS: A consecutive series of 333 patients admitted over 7 years under a single consultant surgeon were studied. Outcome measures included the rate of perioperative neurological complication of any kind, and death. The length of hospital stay and the number of readmissions within 30 days were recorded prospectively by computerized audit. RESULTS: Over the interval of the study, the number of preoperative investigations was reduced; angiography and cerebral computed tomography were reserved for specific indications. The median duration of hospital stay decreased from 7 to 2 days. There was no change in the stroke and death rate (3 per cent) during the study and only two patients required readmission within 30 days. CONCLUSION: Carotid endarterectomy can be performed cost-effectively using non-invasive preoperative investigations for the majority of patients. In-hospital stay has been reduced and the routine use of intensive care replaced by a 2-h stay in theatre recovery. These changes have been achieved without compromising patient safety.

Comparison of intra-arterial digital subtraction angiography, magnetic resonance angiography and duplex ultrasonography for measuring carotid artery stenosis.

BACKGROUND: Duplex ultrasonography and magnetic resonance angiography (MRA) are becoming competitive alternatives to angiography for determining the degree of internal carotid artery (ICA) stenosis. Varying reports have been published regarding the suitability of each technique for grading ICA disease. This retrospective study compared the merits of these three modalities for measuring ICA stenosis. METHODS: One hundred and eleven patients being considered for carotid endarterectomy underwent intra-arterial digital subtraction angiography (DSA) via arch injection. Duplex imaging was performed in all patients and MRA in 50. The degree of carotid stenosis estimated by the three modalities was compared. RESULTS: There was good correlation between subjectively graded MRA and DSA images (r = 0.87, P < 0.001, n = 82 carotids) but poor correlation for objective estimates. MRA tended to underestimate the degree of stenosis (bias - 4.5 per cent) compared with DSA, but showed good correlation with duplex ultrasonography estimates (r = 0. 86, P < 0.001, n = 87 carotids). Both non-invasive modalities produced high values of sensitivity and specificity in estimating stenoses of greater than 70 per cent. MRA was less sensitive for distinguishing between severe stenosis and complete occlusion. CONCLUSION: This study did not resolve the debate regarding the method of choice as both MRA and duplex ultrasonography were accurate for imaging carotid stenoses.

The results of routine primary closure in carotid endarterectomy.

PURPOSE OF STUDY: The aims of this study were to determine the incidence of restenosis following carotid endarterectomy with primary closure of the arteriotomy and to observe the natural history of disease progression in the 1st postoperative year. METHODS: The study group consisted of a consecutive series of 126 patients undergoing carotid endarterectomy. Duplex imaging was performed preoperatively and at 8 weeks, 6 months and 1 year postoperatively. RESULTS: Five patients (4%) had a residual stenosis. At 12 months, the overall restenosis rate was 15%: 8.5% for males and 28.9% for females. None of these restenoses were symptomatic. There was no significant difference in the diameter of the internal carotid artery between male and female patients (U = 896, P = 0.60) and no significant difference in the diameter of the arteries that had restenosed at 12 months and those that had remained patent (U = 391, P = 0.33). CONCLUSIONS: Carotid endarterectomy with primary closure is associated with a low incidence of restenosis in men, but not in women. Criteria for selective patching should consider both gender and vessel calibre.

Carotid plaque characterization by duplex scanning: observer error may undermine current clinical trials.

BACKGROUND AND PURPOSE: Clinical studies currently in progress are using subjective methods to characterize plaque morphology from ultrasound images. However, there are few studies on the intraobserver and interobserver variability of these classifications. This study was designed to assess these variables. METHODS: Grading of plaque morphology from ultrasound images, stored both digitally and to hard copy, was performed by 2 classification schemes. Interobserver agreement was determined by 4 observers. Within-observer agreement was performed at intervals for up to 6 months. Accuracy of the 2 methods was determined by comparison with histology. RESULTS: Within- and between-observer agreement was moderate to good for full-color digital image analyses, with pooled kappa values of kappap=0.49+/-0.10 and kappap=0.62+/-0.07 for the 2-category method and kappap=0.53+/-0.06 and kappap=0.52+/-0.05 for the 4-category method, respectively. Hard copy data analyses gave lower kappa values. The more experienced observers produced higher within-observer agreements and higher correlation with histology. CONCLUSIONS: Reproducible grading of ultrasound images is not consistently achievable among experienced observers, and within-observer agreement may vary with time. The current subjective ultrasound characterization of carotid plaque morphology used in clinical trials may be associated with unacceptable levels of reproducibility in some centers. Variability between observers may be reduced by using the simpler 2-category grading of plaque morphology to interrogate full-color digitally stored images. Observer agreement should be audited regularly.

Intraoperative high resolution duplex imaging during carotid endarterectomy: which abnormalities require surgical correction?

OBJECTIVES: This study evaluates high resolution, duplex ultrasound imaging for quality control of carotid endarterectomy in order to determine which technical factors were linked to residual stenosis and to define duplex criteria for re-exploration. DESIGN, MATERIAL AND METHODS: A consecutive series of 100 patients undergoing carotid endarterectomy were evaluated. Duplex imaging was performed prior to wound closure and repeated at 6-8 weeks postoperatively. Stenoses were classified as non-significant, moderate or severe based on duplex criteria. Intimal flaps, shelves, kinks, clamp damage and fronds were identified by ultrasound imaging. RESULTS: Five moderate stenoses were noted in the proximal endarterectomy site (PES), and at follow-up three had resolved. Adherent fronds were detected in 83% of vessels and resolved in all but three cases. At the distal endarterectomy site there were 10 severe and 12 moderate stenoses. Intimal flaps were associated with an increased incidence of residual stenosis (p = 0.010). CONCLUSIONS: We conclude that severe stenoses with an intimal flap should be corrected immediately. Further data is required to establish the significance of kinks. Residual intimal flaps in the PES appear to remodel. The role of completion duplex may lie in the modification of surgical technique to eradicate anatomical and haemodynamic imperfections.

Measurement of flow in small vessels by magnetic resonance phase mapping techniques: an in vitro and in vivo study.

The measurement of blood flow in small arteries is a potential extension of magnetic resonance (MR) angiography. We have compared flow measurements based on MR phase mapping with those obtained by Doppler ultrasound and electromagnetic flowmetry in both phantom and animal models. Correlation between modalities was high for in vitro studies (R2 = 0.93-0.98). In vivo, electrocardiogram-gated MR and Doppler ultrasound flow measurements compared to electromagnetic flowmetry showed fair correlation coefficients (R2 = 0.73 and 0.66, respectively). However, limits of agreement indicated that in small vessels flow measured by the three modalities could differ by up to +/-90 mL/min. For both models, arteries in the range of 3-6.5 mm in diameter produced complementary errors in area and velocity measurements in MR studies. Ungated MR studies showed a reduced agreement (R2 = 0.88 in vitro, 0.54 in vivo), which may in part be due to poor sampling of the velocity pattern. The results show that the high correlation obtained in vitro cannot be extrapolated to the in vivo situation, where additional physiological and anatomical variables are encountered.

The measurement of internal carotid artery stenosis: comparison of duplex with digital subtraction angiography.

OBJECTIVES: To compare the subjective (eyeballed) method for measuring internal carotid artery (ICA) stenosis by non-selective intra-arterial digital subtraction angiography (IA-DSA) with objective and duplex methods. DESIGN: Retrospective study. MATERIALS AND METHODS: Fifty-three consecutive patients underwent IA-DSA prior to carotid endarterectomy providing 103 carotid angiograms. Objective assessment of ICA stenosis was by the North American Symptomatic Carotid Endarteectomy Trial (NASCET) criterion and the Carotid Stenosis Index (CSI). Duplex estimation of stenosis was derived from peak systolic and diastolic velocities in the ICA and common carotid artery (CCA). RESULTS: The coefficient of repeatability was poorest for NASCET stenosis estimates (40%), whilst the improved values for CSI (20%) were consistent with the lower variability recorded for measuring the CCA diameter. Correlation and agreement levels between subjective (r = 0.80, -41% to +33%) or objective assessments and duplex (NASCET: r = 0.76; -52 to +28%; CSI: r = 0.72; -27 to +39%) showed similar values. CONCLUSIONS: We conclude that the inter-observer variability for assessing angiograms obtained by arch injection is considerable and precludes high agreement when IA-DSA is compared with other methods. As the agreement of duplex ultrasound with IA-DSA is similar to the agreement between DSA methods, duplex can be offered as the first stage assessment of ICA stenosis, with the proviso that the duplex assessment is performed consistently by an experienced operator.

A one-stop vascular clinic: a practical proposition with non-invasive assessment.

One-stop clinics are becoming increasingly popular with both patients and their general practitioners. Traditionally, vascular patients have needed to attend hospital two or three times for clinical examination and investigations. We have introduced a one-stop clinic for patients with lower limb arterial disease (LLAD) and aortic aneurysms. In 92 clinics over 2 years, 1194 new patients and 1409 follow-up patients were seen, with LLAD being the largest single category comprising 40% of the patients seen, followed by varicose veins (25%), carotid disease (12%), and aortic aneurysms (8%). Overall, 57% of patients had non-invasive imaging performed, either in the clinic or on a separate visit. Performing all LLAD and aortic scans in the clinic requires 1.9 h of imaging time per clinic. Extending in-clinic scanning to patients with varicose veins and carotid disease would increase this to 3.9 h of scanning per clinic and require a duplex scanner and an additional technologist in the clinic.

Comparison of indirect and direct blood pressure measurements with Osler's manoeuvre in elderly hypertensive patients.

Indirect (cuff) and direct (intra-arterial) BPs were measured in 15 normotensive (mean age 79 years, range 72-88 years) and 21 hypertensive (mean age 76 years, range 65-89 years) elderly patients. Osler's test and arm arterial compliance, measured using Doppler-shifted ultrasound, were also assessed. In the normotensive, cuff systolic pressures were less than the direct by > 20 mmHg in 10 of the 15 (mean cuff systolic 139 +/- 13: direct 160 +/- 20 mmHg, P < 0.001); there was no statistical difference between the cuff and direct mean diastolic pressures (mean cuff diastolic 75 +/- 8; direct 70 +/- 10 mmHg). In the hypertensives, one had pseudohypertension (cuff systolic 186: direct 152 mmHg). However, cuff systolic pressures were less than the direct by > 20 mmHg in 11 (mean cuff systolic 205 +/- 26: direct 224 +/- 31 mmHg, P < 0.05); cuff diastolic pressures were greater than the direct by > 10 mmHg in 10 (mean cuff diastolic 102 +/- 14; direct 93 +/- 16 mmHg, P < 0.05). There was no significant difference between cuff and direct mean arterial pressures or the compliance in the normotensive and hypertensive groups. Osler's test was negative in the pseudohypertensive patient while in the four positive tests cuff systolic pressures were less than the direct measurements. In elderly patients there was no significant difference between the mean BP for cuff and direct measurements; systolic pseudohypotension and diastolic pseudohypertension are common and Osler's test is misleading.

A variable pitch oxygen saturation indicator designed for use in the magnetic resonance environment.

Many commercially available pulse oximeters have a variable pitch blood oxygen saturation indicator, which emits a 'beep' between 175 Hz and 675 Hz with each heart beat. The frequency of this beep is dependent on the blood oxygenation measured by the oximeter, higher frequencies corresponding to higher blood saturation percentages. This is a useful feature for an anaesthetist, rapidly communicating potentially life-threatening situations in an easily detectable manner. Most available oximeters with an audio output feature are vulnerable to the effects of magnetic resonance scanning. In this article an add-on module is described for generating a beep to indicate the blood oxygen saturation which has been specifically designed to operate in the MR environment.

Non-invasive assessment of the Circle of Willis using transcranial pulsed Doppler ultrasound with angiographic correlation.

The ability of transcranial pulsed Doppler ultrasound (TCD) to provide a dynamic assessment of the functional capability of the Circle of Willis was assessed using conventional cerebral angiography for anatomic correlation. Eleven patients had normal four-vessel cerebral angiography prior to being investigated with ultrasound. Angiography and ultrasound both demonstrated a functional anterior communicating artery in nine of the eleven patients, giving complete agreement between the two techniques. Posterior communicating arteries were visualized angiographically in all eleven patients. Ultrasound identified bilateral functional vessels in nine, the other two patients having non-functional vessels. In these latter two patients, angiography demonstrated three of the four posterior communicating arteries to be hypoplastic and it was uncertain whether these vessels carried significant blood flow. The fourth posterior communicating artery was shown to have an absent proximal segment of the ipsilateral posterior cerebral artery, with a persistent fetal posterior communicating artery. This anatomical variation is a potential limitation of ultrasound for assessing functional posterior communicating arteries. These preliminary results indicate that a combination of the anatomical (angiographic) and dynamic (ultrasonic) data may prove to be complementary for assessing the Circle of Willis.

Dural sinus thrombosis. Diagnosis and follow-up by magnetic resonance angiography and imaging.

Magnetic resonance imaging has been reported to have advantages over conventional angiography in the diagnosis of dural sinus thrombosis. A case report is presented describing the application of MR techniques including MR angiography, to diagnose and monitor therapy for dural sinus thrombosis.