Accuracy of duplex ultrasound in evaluating carotid artery anatomy before endarterectomy

PURPOSE: Anatomic features, such as a high carotid bifurcation (< 1.5 cm from the angle of the mandible), excessive distal extent of plaque (> 2.0 cm above the carotid bifurcation), or a small diameter (< or = 0.5 cm) redundant or kinked internal carotid artery can complicate carotid endarterectomy. In the past, arteriography was the only preoperative study capable of imaging these features. This study assessed the ability of duplex ultrasound to evaluate their presence before surgery. METHODS: A consecutive series of 20 patients who underwent 21 carotid endarterectomies had preoperative duplex ultrasound evaluations of these anatomic features. These evaluations were correlated with operative measurements from an observer blinded to the duplex findings. RESULTS: The mean difference between duplex and operative measurements for the distance between the carotid bifurcation and the angle of the mandible, the distal extent of plaque, and the internal carotid artery diameter was 0.9 cm, 0.3 cm, and 0.8 mm, respectively. The correlation coefficient between the two methods was 0.86, 0.75, and 0.59, respectively. Duplex ultrasound predicted a high carotid bifurcation, excessive distal extent of plaque, or a redundant or kinked internal carotid artery with 100% sensitivity (p < 0.05, p < 0.01, and p < 0.001, respectively). The sensitivity of duplex ultrasound in predicting a small internal carotid artery diameter was 80%. The specificity of duplex ultrasound for predicting excessive distal extent of plaque, small internal carotid artery diameter, high carotid bifurcation, and a coiled or kinked carotid artery was 92%, 56%, 100%, and 100%, respectively. CONCLUSION: Duplex ultrasound can predict the presence of anatomic features that may complicate carotid endarterectomy. Preoperative duplex imaging of these features may be helpful in patients who undergo carotid endarterectomy without preoperative arteriography.     

Profile of anti-stratum corneum autoantibodies in patients with aural cholesteatoma

A study was performed to evaluate immediate changes in carotid artery blood flow after carotid endarterectomy using a Doppler ultrasonographic flowmeter. Forty-seven consecutive patients aged 49-78 (median 64) years with symptomatic internal carotid artery (ICA) stenosis underwent carotid endarterectomy. Volume flow, resistance and pulsatility index were measured in the common carotid artery (CCA) and ICA both before and after operation. ICA flow increased by 54 per cent (P < 0.01) and resistance decreased by 58 per cent (P = 0.01). CCA flow rose by 17 per cent (P = 0.1) and resistance fell by 21 per cent (P = 0.02). The pulsatility index did not change significantly. The Doppler ultrasonographic flowmeter offers a simple, non-invasive and convenient means of improving understanding of the immediate haemodynamic effects of carotid endarterectomy. It is useful in everyday practice to confirm the adequacy of endarterectomy, particularly in the absence of other methods of quality control. Duplex ultrasonography might still be necessary after surgery if the flowmeter does not demonstrate an increase in flow compared with the preoperative value.     

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 (> or = 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.     

Endoluminal repair of internal carotid artery aneurysm: a feasible but hazardous procedure

PURPOSE: The aim of this study was to report the repair of an aneurysm of the internal carotid artery using the endoluminal method. METHODS: A 70-year-old male patient noted a swelling in the right side of his neck 22 years after endarterectomy of the right internal carotid artery. Duplex ultrasound confirmed the clinical diagnosis of aneurysm of the internal carotid artery. Further investigation included contrast-enhanced computed tomographic (CT) scanning and carotid angiography performed via a retrograde femoral approach. The aneurysm contained thrombus and was 3 cm in diameter and in length. It extended superiorly from a point 0.5 cm above the carotid bifurcation to a point estimated to be 2 cm from the base of the skull. Repair of the aneurysm was undertaken using the endoluminal method. A self-expanding endograft 8 mm in diameter and 4 cm in length was introduced through a 12F sheath in the common carotid artery. An on-table completion angiogram of the right-sided extracranial carotid arteries and the intracranial internal carotid artery and branches was obtained. RESULTS: The completion angiogram and postoperative CT scan confirmed exclusion of the aneurysm sac from the circulation. The patient awoke from anesthesia with complete paralysis of the left arm. Recovery of movement commenced 1 hour later. A brain CT scan demonstrated the event to be an embolic stroke. Strength had returned by 7 days. Function of the arm was good 1 month after operation, but coordination for fine movements was lacking. At the 6-month follow-up, good arm function was maintained. A duplex ultrasound scan demonstrated not only continued exclusion of the aneurysm sac but occlusion of the endograft, also. CONCLUSIONS: Endoluminal repair of aneurysms of the internal carotid artery is feasible but carries the risk of major morbidity as a result of peripheral embolization and early occlusion of the endograft.     

Changes over time in optimal duplex threshold for the identification of patients eligible for carotid endarterectomy

BACKGROUND AND PURPOSE: Two surgical trials established that carotid endarterectomy is beneficial to symptomatic patients who have a severe internal carotid artery (ICA) stenosis on angiograms. Duplex ultrasonography-derived hemodynamic parameters show a good correlation with angiography and are often used for detecting severe ICA stenoses. However, duplex performance is ultrasound machine and operator dependent. Over time both may change, possibly affecting duplex performance. We compared duplex performance of 2 time periods in 1 specific vascular laboratory using angiography as the gold standard. METHODS: Consecutive patients who underwent both angiography and duplex examinations of the ICA were evaluated (first period, 60 patients; second period, 61 patients). Peak systolic velocity and several other hemodynamic parameters and ratios were analyzed by receiver operating characteristic curves in their ability to detect severe ICA stenoses. The optimal parameter and threshold were determined for each period. Subsequently, duplex test characteristics were compared after the optimal thresholds of both the first and the second periods were applied in the second period. RESULTS: In both periods peak systolic velocity of the ICA was the best test parameter; areas under the receiver operating characteristic curve were similar (0.957 and 0.954, respectively). However, the optimal threshold was different. The optimal threshold in the second period was 270 cm/s. When the optimal threshold of 210 cm/s of the first period was applied in the second period, test characteristics changed significantly. Sensitivity increased from 98% to 100%, and specificity decreased from 85% to 71% (P=0.004). CONCLUSIONS: The optimal threshold for detecting severe ICA stenoses with duplex ultrasonography in our laboratory changed over time. Individual laboratories should assess duplex accuracy regularly and adjust adopted criteria if necessary to keep diagnostic performance optimal.     

Complete MR angiography and Doppler ultrasound as the sole imaging modalities prior to carotid endarterectomy

OBJECTIVE: To assess the combination of duplex Doppler ultrasound (DUS) and complete carotid magnetic resonance angiography (MRA) for the non-invasive imaging of carotid disease and their effect on outcomes. Determine inter-reader agreement of carotid MRA. MATERIALS AND METHODS: One-hundred and ten carotid bifurcations were evaluated using DUS, 2D and 3D time-of-flight MRA from the aortic arch to the Circle of Willis in 55 patients. Percentage stenoses were determined by two blinded readers using standardized criteria. Clinical follow-up was by chart review. RESULTS: Correlation of Doppler and MRA was excellent (r=0.903, P<0.001). Inter-reader agreement (K) for MRA was good: internal carotid artery (ICA) (0.750), external carotid artery (ECA) (0.674) and common carotid artery (CCA) (0.410). Differences in CCA readings were due to minor differences in categorizing lesions as CCA versus ICA or ECA. MRA and Doppler detected nine occluded ICAs. Two DUS occlusions had ICA flow by MRA; one due to a reconstituted precavernous ICA, one a near occluded vessel. Five patients (9%) had surgical management modified by MRA with four not having surgery: three distal ICA/Siphon occlusions and one less severe stenosis by MRA. One tandem lesion not visualized by DUS was surgically significant. Nine aortic arch abnormalities had no surgical impact, possibly due to small sample size. Of 41 endarterectomies, there were no complications from errors of diagnosis. CONCLUSION: Carotid MRA correlates well with DUS with good inter-reader agreement. MRA confirms Doppler findings, expands anatomical information and identifies tandem lesions from the aortic arch to the Circle of Willis which can affect surgical management. This approach to carotid artery imaging appears to have no negative effect on surgical outcome.     

Genetic basis of variation in carotid artery wall thickness

BACKGROUND AND PURPOSE: Other than the documented associations of risk factors and carotid artery wall thickness, the genetic basis of variation in carotid artery intimal-medial thickness (IMT) is unknown. The purpose of this study was to examine the extent to which variation in common carotid artery (CCA) IMT and internal carotid artery (ICA) IMT are under genetic control. METHODS: The sibship data used for this analysis were part of an epidemiological survey in Mexico City. The CCA and ICA analyses were based on 46 and 44 sibships of various sizes, respectively. The CCA and ICA IMTs were measured with carotid ultrasonography. Using a robust variance decomposition method, we performed genetic analyses of CCA IMT and ICA IMT measurements with models incorporating several cardiovascular risk factors (eg, lipids, diabetes, blood pressure, and smoking) as covariates. RESULTS: After accounting for the effects of covariates, we detected high heritabilities for CCA IMT (h2 = 0.92 +/- 0.05, P = .001) and ICA IMT (h2 = 0.86 +/- 0.13, P = .029). Genes accounted for 66.0% of the total variation in CCA IMT, whereas 27.7% of variation was attributable to covariates. For ICA IMT, genes explained a high proportion (74.9%) of total phenotypic variation. The covariates accounted for 11.5% of variation in ICA IMT. CONCLUSIONS: Our results suggest that substantial proportions of phenotypic variance in CCA IMT and ICA IMT are attributable to shared genetic factors.     

The heart rate after inhibition of nitric oxide release in the anaesthetized dog

BACKGROUND AND PURPOSE: The North American Symptomatic Carotid Endarterectomy Trail (NASCET) demonstrated the benefit of carotid endarterectomy for symptomatic patients with > or = 70% carotid stenosis. Screening for detection of significant carotid occlusive disease has relied on duplex Doppler imaging. However, traditional duplex categories (50% to 79%, 80% to 99%) are not directly applicable to NASCET. We sought to evaluate duplex criteria for determination of > or = 70% carotid stenosis. METHODS: Duplex scan and arteriograms of 110 patients (210 carotids), performed within 1 month of each other, were reviewed by blinded readers. Arteriographic stenosis was determined by the NASCET method. Duplex measurements of peak systolic and end-diastolic velocity (PSV, EDV) were recorded, and ratios of velocities in the internal and common carotid arteries (ICA, CCA) were calculated. Receiver-operator characteristic (ROC) curves of sensitivity, specificity, positive and negative predictive values (PPV, NPV), and accuracy were determined. RESULTS: Interobserver agreement for measurement of arteriographic stenosis was "almost perfect" (kappa=0.86). The criteria chosen for detection of > or = 70% stenosis were PSVICA>210 cm/s (sensitivity, 94%; specificity, 77%; PPV, 68% NPV, 96% accuracy, 83%) EDVICA>70 cm/s (sensitivity, 92%; specificity, 60%; PPV, 73%; NPV, 86%; accuracy 77%), PSVica/PSVCCA >3.0 (sensitivity, 91%; specificity, 78%; PPV, 70%; NPV, 94%; accuracy, 83%), and EDVICA/EDVCCA>3.3 (sensitivity, 100%; specificity, 65%; PPV, 65% NPV, 100%; accuracy, 79%). CONCLUSIONS: We conclude that > or = 70% carotid stenosis can be reliably determined by duplex Doppler ultrasound. Individual vascular laboratories must validate their own results.     

Varying impact of common carotid artery digital compression and internal carotid artery balloon test occlusion on cerebral hemodynamics

BACKGROUND: The purpose of this study was to compare the cerebral hemodynamic changes brought about by common carotid artery (CCA) digital compression and angiographic internal carotid artery (ICA) balloon occlusion. METHODS: Bilateral transcranial Doppler ultrasonographic monitoring of the middle cerebral artery blood velocity (VMCA) was performed in 12 subjects with neck neoplasms or traumatic carotid-cavernous fistulas. The MCA pulsatility index (PIMCA) and hemodynamic tension (Uhem MCA) were calculated. RESULTS: Common carotid artery compression provoked the largest drop in ipsilateral VMCA, PIMCA, and Uhem MCA. Common carotid artery compression caused a steal of blood from the intra- to the extracranial circulation, with the discrepancy in hemodynamic findings between CCA and ICA test occlusions being dependent on the quantity of reversed ipsilateral ICA blood flow. CONCLUSION: If the carotid artery is to be sacrificed, permanent ICA closure is the procedure of choice with respect to the occurrence of cerebral ischemic lesions in patients with neck neoplasms and ICA flow reversal during CCA compression.     

Carotid stenosis--is arteriography necessary in investigation and treatment

The present study was undertaken in order to evaluate whether arteriography changed the planned treatment (carotid endarterectomy) of patients with symptomatic carotid artery disease, who had been investigated primarily by ultrasound Duplex scanning. The material was comprised of 50 consecutive patients admitted for arteriography. All patients were symptomatic and were by ultrasound examination found to have lesions of the relevant internal carotid artery (ICA). In three cases arteriography was performed because ultrasound examination was inconclusive. Of the remaining 47 cases, arteriography only changed the planned treatment in three. In one case, arteriography showed a long stenosis continuing into the intracranial part of the ICA, which was not observed by ultrasound. In two cases of minor disease ultrasound overestimated the degree of stenosis. The study concludes that carotid endarterectomy may be performed based on ultrasound duplex scanning, without prior arteriography, if the degree of stenosis is 70% or greater and if the distal end of the stenosis is clearly extracranial.     

Collateralization of an occluded internal carotid artery via a vas vasorum

BACKGROUND: Reopening of an occluded internal carotid artery (ICA) is often seen in dissections but only rarely occurs in atherothrombotic occlusion of the internal carotid artery. CASE DESCRIPTION: A 60-year-old man suffered a minor stroke with dysphasia in March 1995. Color-coded duplex ultrasonography of his neck arteries revealed a left ICA occlusion. He was placed on a regimen of aspirin and followed up clinically and with ultrasonography. At follow-up 18 months later, the patient was asymptomatic. On duplex ultrasonography his left occluded ICA was found to be reopened, with a residual, proximal, high-grade stenosis. However, intra-arterial digital subtraction angiography demonstrated a persistent ICA occlusion and a vas vasorum originating from the carotid bulb and draining into the ICA distal to the occlusion. CONCLUSIONS: The rare collateralization of an occluded ICA by vasa vasorum seems to take several months. It can be a pitfall in the ultrasound diagnosis of carotid artery occlusive disease.     

Clinical and laboratory experience with heparin-impregnated silicone shunts for carotid endarterectomy

Our experience with use of a Silastic shunt for carotid endarterectomy is reviewed briefly, and the complication of shunt thrombosis despite intraoperative administration of heparin is noted. Of obvious importance are the reduction of blood flow and the possibility of embolization caused by accumulating thrombus. Shunt thrombosis has been abolished by the use of heparin-impregnated Silastic shunts. In experiments in dogs, such heparin-treated shunts showed greater thromboresistance than did untreated shunts.     

Macroscopic and pathohistological investigation of endarterial plaque after intraoperative balloon dilatation of the carotid artery during carotid endarterectomy

Twelve patients associated with stenosis of the extracranial carotid artery underwent intraluminal balloon dilatation during carotid endarterectomy (CEA). There were 11 men and 1 woman, and age ranged from 56 to 73 years old. The rate of stenosis, shown by angiography, in each patient was from 60 to 85% in width. After securing carotid blood flow by a T-shaped shunt tube, a balloon catheter was inserted from the exposed common carotid artery into the internal carotid artery. The balloon was inflated three or four times with 2.5-3.5 atm. for 30-40 seconds. Immediately after balloon dilatation, endoscopic investigation was performed (Wolf; hard type endoscope, 2.7 mm diameter). Then CEA was performed using the usual procedure. The removed endarterial plaque was investigated pathohistologically. In macroscopic and endoscopic findings, there were 6 patients with mural thrombosis, 4 patients with laceration of the intima, and one patient with outflow of atheroma from the intima. Only 3 patients had increase in lumen after balloon dilatation. In pathohistological appearance, all patients had a moderate degree of fibrosis, calcification, and atheroma in the cross section of the plaque. Ten patients had intramural hemorrhage. Three typical patients were revealed by the use of angiographical, ultrasonographical, endoscopic, and pathohistological presentation. Case 10 showed laceration of the intima by balloon dilatation, and had moderate increase in lumen size macroscopically and endoscopically. There were moderate cases of fibrosis, calcification, atheroma, and intramural hemorrhage. Dilatation of the lumen seemed to be accomplished by a decrease in thickness of the atheroma and intramural hemorrhage. Case 8 demonstrated an increase in lumen size, but also laceration of the intima and outflow of atheroma from the arterial wall. There were much atheroma and large intramural hemorrhage in the intima, which might become a source of enbolism. Case 7 revealed no laceration of the intima and no increase in lumen size. Preoperative ultrasonography showed hyperechoic finding and postoperative pathohistological findings showed severe fibrosis and calcification, which were thought to have interrupted balloon dilatation. There have been small numbers of reports about pathohistological presentation after percutaneous transluminal angioplasty (PTA), because it is very difficult to take a specimen after PTA. In this report we were able to present the necessity of preoperative investigations by angiography, ultrasonography, and 3D-CT.     

Evaluation of carotid endarterectomy with sequential MR perfusion imaging: a preliminary report

BACKGROUND AND PURPOSE: Current indications for carotid endarterectomy are determined by balancing the relative risks of surgery with the benefits of reduced risk of subsequent stroke. Our purpose was to use MR perfusion imaging to assess patients being considered for carotid endarterectomy and to monitor sequential changes in MR perfusion characteristics after surgery. In particular, we wished to determine whether this technique could be used to detect changes that might be related to post-carotid endarterectomy hyperemia. METHODS: We used a single-section gradient-recalled echo sequence to investigate 14 patients being examined before possible surgery for carotid artery disease. In the 12 patients in whom carotid endarterectomy was performed, sequential studies were performed 3 to 5 days after surgery and at 3 months. Analysis of bolus-arrival-time (BAT) images was performed. RESULTS: Significant delays in preoperative BAT images of 0.89 seconds (range, 0.05 to 3.22 seconds) were apparent between hemispheres. Excluding the two patients with contralateral internal carotid artery (ICA) occlusion, early arrival, possibly indicating postoperative hyperemia, was seen in five patients immediately after carotid endarterectomy but resolved within 3 to 5 months after surgery. CONCLUSION: MR perfusion imaging shows differences in BAT between hemispheres in patients with ICA stenosis. Changes in perfusion characteristics after carotid endarterectomy are complex, and early BAT on the operative side can occur soon after endarterectomy in over half those patients without an occluded contralateral vessel. The significance of these findings with regard to patient outcome and risk of postoperative hyperemia requires further investigation.     

Acute platelet deposition after carotid endarterectomy in sheep: vein patch compared with gelatin-sealed Dacron and polytetrafluoroethylene patch closure

PURPOSE: Patch angioplasty is commonly used to close the arteriotomy after carotid endarterectomy is performed. The purpose of this study was to determine whether any significant variations were present in platelet deposition for different patch sizes and materials. METHOD: The study measured 111-indium-labeled uptake in the sheep to compare thrombus deposition for three different patch materials: autologous vein, gelatin-sealed Dacron, and polytetrafluoroethylene and for 6- and 12-mm patch widths. Platelet uptake was measured on the patch itself and on the artery wall that was opposite to the patch and that had undergone endarterectomy. Scanning electron microscopy was used to confirm the localization of the labeled platelets on the patch and on the surface that had undergone endarterectomy. RESULTS: Although considerable variation was seen among animals, platelet accumulation was lowest in the vein patches compared with the prosthetic patches (p < 0.01), but the deposition on the gelatine-sealed Dacron was not significantly different from that on polytetrafluoroethylene patches. Platelet deposition on the artery wall that had undergone endarterectomy was considerably less than on the patch but was higher when a synthetic patch was used rather than a vein patch (p < 0.05). CONCLUSIONS: Acute thrombus deposition after carotid endarterectomy was considerably less for vein patch closure than for synthetic patches. A 6-mm patch width caused less thrombus deposition both on the patch itself and on the artery wall compared with a 12-mm patch, but the difference was proportional to the patch width.     

MR imaging of the liver with Resovist: safety, efficacy, and pharmacodynamic properties

PURPOSE: To determine whether ultrasound (US) is a sensitive follow-up method after placement of a carotid artery stent for the detection of significant stenosis, occlusion, and other complications at early and intermediate follow-up. MATERIALS AND METHODS: Doppler US examinations were performed after stent placement in 170 carotid arteries in 119 patients with angiographic correlation. Prospective diagnostic US criteria for stenosis were peak-systolic velocity greater than 1.25 m/sec, internal carotid artery (ICA) to common carotid artery (CCA) peak-systolic velocity ratio of greater than or equal to 3:1, and intrastent doubling of peak-systolic velocity. Retrospective criteria for stenosis were also applied: peak-systolic velocity greater than 1.7 m/sec, ICA end-diastolic velocity greater than 0.4 m/sec, ICA/CCA peak-systolic velocity ratio greater than 2.0, and ICA/CCA end-diastolic velocity ratio greater than 2.4. RESULTS: Eighty-seven immediate and 83 intermediate (average, 7.3 months) follow-up US examinations were performed. Two stent occlusions were detected. One or more prospective US criteria were abnormal in 26 arteries with a stent. One or more retrospective criteria were positive in 47 arteries. Angiography showed corresponding findings, with only one significant stenosis (63%) in the ICA stents. Moderate collapse of a CCA stent was depicted at US. CONCLUSION: Only one significant recurrent stenosis was detected, and no significant stenoses were missed at US. US successfully depicted carotid artery stent occlusion and a moderate stent collapse. Sensitivity in the detection of intrastent stenosis is promising. Further study to refine US criteria in a study with longer term follow-up is needed owing to the lack of significant recurrent stenosis in the intermediate follow-up group.     

Differences in strategies for carcinoma of the pancreas between Japan and western countries

This study defines normative flow velocity (FV) ranges for the common carotid (CCA), internal carotid (ICA) and middle cerebral arteries (MCA), compares them to subjects with nonfocal vascular disease (mild to moderate hypertension, diabetes, hyperlipidemia or coronary artery disease), and clarifies the association between carotid and MCA FVs. FVs were measured by carotid and transcranial Doppler ultrasonography in 278 healthy and 190 vascular-disease subjects. Normative FV ranges for CCA, ICA and MCA were large in healthy subjects, with modest gender and age differences. Vascular-disease subjects had similar FVs to healthy controls. MCA FVs were significantly correlated with carotid FVs (r ranged 0.26-0.50), but were only weakly or not significantly associated with them (beta ranged 0.08-0.18) when controlling for age and gender. These findings suggest that normative FVs are not affected by the presence of nonfocal vascular disease, but carotid FVs do not aid in assessing MCA FVs.     

Multiple pregnancy and microelements: zinc (preliminary report)

Incidence, causes and results of permanent ICA clipping during arterial cerebral aneurysm surgery were analyzed in randomized group of 470 patients. Permanent ICA clipping was performed in 6 cases (1.3% of all surgeries). The causes of permanent ICA clipping were ICA wall rupture in 4 (0.9%) cases, bleeding from aneurysms of the ophthalmic segment of the internal carotid artery (ICA) in 2 (0.4%). Atherosclerotic changes of ICA were found and verified by biopsy in all cases of ICA rupture. Two variants of rupture were identified. ICA aneurysm avulsion from the artery in the area of aneurysmal neck with vascular wall defect development in 2 (0.6%) cases; in the second variant, ICA rupture was caused by frontal lobe traction. In the study group aneurysms of ophthalmic segment of ICA were found in 19 cases: intraoperative bleeding rate was 31% (6 cases). ICA was clipped in 33% of all cases of intraoperative bleeding. Among 6 patients with permanent ICA clipping, 5 died. Deaths were caused by cerebral infarction in 4 cases and acute blood loss in 1 case.     

Radiofluorinated L-m-tyrosines: new in-vivo probes for central dopamine biochemistry

PURPOSE: Recent information indicates that large, sustained wall shear stress gradients are a dominant hemodynamic parameter associated with the location and severity of atherosclerosis and myointimal hyperplasia. This study computes the spatial values of wall shear stresses and their gradients for three carotid artery bifurcation geometries. METHODS: A computational fluid dynamics program was used to solve the transient two-dimensional partial differential equations that describe fluid flow. Blood was treated as both a Newtonian and a non-Newtonian incompressible fluid. Solutions for the velocities, wall shear stresses, and wall shear-stress gradients were obtained for three carotid bifurcation geometries: a normal carotid bifurcation (similar to a primarily reconstructed carotid endarterectomy), a patch-reconstructed carotid endarterectomy, and a gradually tapered, low-angle carotid bifurcation (no carotid bulb). RESULTS: Computed velocity profiles closely match published experimental ones. Disturbed flow velocities are largest in the bulb segment of the normal carotid bifurcation. Peak and minimum wall shear stresses and peak shear stress gradients occurred in the lateral internal carotid artery wall. These were binodal in the normal or primarily reconstructed carotid artery, localized at the distal end of the patch-reconstructed carotid bifurcation, and minimal in the smooth, tapered carotid bifurcation. Wall shear stresses and their gradients were slightly higher for non-Newtonian than Newtonian fluids in the normal carotid artery but were similar in the other two geometric configurations. CONCLUSION: These results indicate that flow disturbances in general and wall shear stress gradients in particular are markedly reduced in carotid artery bifurcations that are smooth and gradually tapered and do not have a bulb. Abrupt geometric wall changes such as those occurring in the normal carotid bulb and at the distal end of a patch-reconstruction after carotid endarterectomy are harbingers of disturbed flow and high wall shear stress gradients. These results suggest that carotid endarterectomy reconstruction geometry characterized by a gradually tapered internal carotid artery may minimize the hemodynamically induced component of early myointimal hyperplasia and thrombosis and late atherosclerotic restenosis.     

Ultrasonographically assessed maximum carotid artery wall thickness in Mexico City residents and Mexican Americans living in San Antonio, Texas. Association with diabetes and cardiovascular risk factors

Measurements of carotid artery wall thickness are often used as a surrogate for atherosclerosis. However, few studies have performed these measurements in populations of Mexican origin. Since Mexicans in Mexico City consume high-carbohydrate diets and have carbohydrate-induced dyslipidemia (high triglyceride and low HDL cholesterol levels) compared with Mexican Americans living in San Antonio, Tex, we questioned whether they also had more atherosclerosis than San Antonio Mexican Americans. Mean maximum intimal-medial thickness (IMT) of the common (CCA) and internal (ICA) carotid arteries were measured in 867 subjects aged 35 to 64 years (40% men) in two Mexican-origin populations, one from San Antonio (n = 202) and the other from Mexico City (n = 665). IMT's in the two cities were compared, and their associations with cardiovascular risk factors were analyzed. Older age, male sex, high levels of total cholesterol, low levels of HDL cholesterol, and high systolic blood pressure were positively associated with both CCA IMT and ICA IMT. Cigarette smoking was significantly associated with ICA IMT. CCA and ICA IMTs in diabetic subjects were thicker than in nondiabetic subjects in both men and women (all P < = .05). CCA IMT was thicker in the San Antonio than the Mexico City subjects after adjustment for cardiovascular risk factors (0.81 versus 0.76 mm in men and 0.77 versus 0.71 mm in women; P < .001 for city difference). San Antonio men also had thicker ICA IMT than their counterparts in Mexico City (0.88 versus 0.83 mm), but the reverse was true for women (0.73 versus 0.77 mm; interaction between sex and city, P < .05). Our results indicate that men had higher carotid IMTs than women. CCA IMT was thicker in San Antonio Mexican Americans than in Mexico City residents. The differences in ICA IMTs between San Antonio and Mexico City were inconsistent. Thus, since Mexico City residents consume high-carbohydrate diets, the data do not support an atherogenic effect of such diets. The interaction between sex and city on ICA IMT deserves further study.