The natural history of the external carotid artery after carotid endarterectomy: implications for management

Thrombosis of External Carotid Artery after Internal Artery Endarterectomy Causing Ischemic Events

Carotid endarterectomy (CEA) is a widespread and safe procedure associated with very little risk. Only at our hospital surgeons perform nearly 1000 of these surgeries annually, with serious complications occurring extremely rarely[1]. Cerebral ischemic events due to external carotid artery (ECA) thrombosis following a successful internal carotid artery (ICA) endarterectomy is one of such complications. We present a case of ECA thrombosis, following ICA endarterectomy that caused ischemic events.

Impact of external carotid artery occlusion at declamping of the external and common carotid arteries during carotid endarterectomy on development of new postoperative ischemic cerebral lesions

OBJECTIVE

The external carotid artery (ECA) is inadvertently occluded during carotid endarterectomy (CEA). The importance of ECA occlusion has been emphasized as a loss of extracranial to intracranial collaterals, a source of chronic embolization, or a site for extended thrombosis during wound closure. This study aimed to determine whether ECA occlusion that inadvertently developed during endarterectomy and that was eventually detected using blood flow measurement of the ECA after declamping of all carotid arteries is a risk factor for development of new postoperative ischemic lesions at declamping of the ECA and common carotid artery (CCA) while clamping the internal carotid artery (ICA). This study also aimed to determine whether intraoperative transcranial Doppler (TCD) monitoring predicts the risk for development of such lesions.

METHODS

This was a prospective observational study that included patients undergoing CEA for severe stenosis (≥70%) of the cervical ICA. When blood flow through the ECA measured using an electromagnetic flow meter decreased rapidly on clamping of only the ECA before carotid clamping for endarterectomy and was not changed by clamping of only the ECA after carotid declamping following endarterectomy, the patient was determined to have developed ECA occlusion. These patients underwent additional endarterectomy for the ECA. TCD monitoring in the ipsilateral middle cerebral artery was also performed throughout surgery to identify microembolic signals (MESs). Brain magnetic resonance diffusion-weighted imaging (DWI) was performed before and after surgery.

RESULTS

There were 104 patients enrolled in the study. Eight patients developed ECA occlusion during surgery. The incidence of intraoperative ECA occlusion was significantly higher in patients without MESs at the phase of ECA and CCA declamping (8/12 [67%]) than in those with MESs (0/92 [0%]; P < .0001). Six patients exhibited new postoperative ischemic lesions on DWI. The incidence of intraoperative ECA occlusion (P < .0001) and the absence of MESs at declamping of the ECA and CCA while clamping the ICA (P <. 0001) were significantly higher in patients with development of new postoperative ischemic lesions on DWI than in those without. Sensitivity and specificity for the absence of MESs at declamping of the ECA and CCA while clamping the ICA for predicting development of new postoperative ischemic lesions on DWI were 100% (6/6) and 94% (92/98), respectively.

CONCLUSIONS

ECA occlusion at declamping of the ECA and CCA while clamping the ICA during CEA is a risk factor for development of new postoperative ischemic lesions. Intraoperative TCD monitoring accurately predicts the risk for development of such lesions.

Effect of internal carotid artery stenting on superior thyroid artery Doppler flow

OBJECTIVES

Patients with carotid disease are frequently referred for carotid artery stenting based on the results of carotid duplex studies. During carotid artery stenting, the stent is usually extended into the common carotid artery, thereby crossing the external carotid artery. Previous studies have shown conflicting results regarding internal carotid stenting and external carotid artery flow velocities, but the effect of stenting on ipsilateral superior thyroid artery velocities has not been defined. This study examined the effect of internal carotid angioplasty and stenting on the ipsilateral superior thyroid artery Doppler-derived flow parameters.

METHODS

We prospectively studied preinterventional and postinterventional duplex scans obtained from 41 patients (mean age ± SD, 64 ± 10 years) who underwent carotid artery stenting. The Doppler-defined preprocedural peak systolic velocity (PSV) end-diastolic velocity (EDV), resistive index (RI), and pulsatility index (PI) in the ipsilateral external carotid and superior thyroid arteries were compared with postprocedural values.

RESULTS

Among patients with stenting, the preprocedural PSV, EDV, RI, and PI in the ipsilateral superior thyroid artery were 30 ± 11 cm/s, 13 ± 6 cm/s, 0.62 ± 0.11, and 1.04 ± 0.28,respectively; after stenting, they were 36 ± 8 cm/s, 14 ± 9 cm/s, 0.71 ± 0.07, and 1.11 ± 0.19. The preprocedural PSV, EDV, RI, and PI in the ipsilateral external carotid artery were 79 ± 24 cm/s, 17 ± 7 cm/s, 0.77 ± 0.26, and 1.27 ± 0.22; after stenting, they were 94 ± 31 cm/s, 20 ± 6 cm/s, 0.80 ± 0.4, and 1.25 ± 0.31. Despite a slight increase in superior thyroid and external carotid artery flow, there was no statistically significant change from before to after stenting.

CONCLUSIONS

This study showed no differences in blood velocity profiles in the ipsilateral superior thyroid and external carotid arteries after stenting.

Outcome of the external carotid artery following carotid endarterectomy with added external carotid artery eversion endarterectomy

OBJECTIVE

To study the results of eversion endarteterctomy of the external carotid artery (ECA) performed as part of standard CEA at a tertiary referral center using duplex ultrasonography.

MATERIALS AND METHODS

Sixty patients (18 women and 42 men) who underwent 65 carotid endarterectomies at Waikato Hospital between January 2006 and July 2007 for significant internal carotid artery (ICA) disease were studied. The procedure also included eversion endarterectomy of the ECA with sharp transection at eversion end point. Preoperative and postoperative duplex scans were performed for all patients using Acuson (USA) ultrasound machine and by one sonographer. Postoperative follow-up scans at periods between 6 weeks and 18 months were reviewed and analyzed with Ascer et al. Doppler ultrasound-scan peak systolic velocity (PSV) criteria.

RESULTS

Preoperative scans revealed significant bifurcation disease involving both ICA and ECA in all patients. The first post operative scan, done six weeks post-operatively, revealed one incomplete ECA endarterectomy, resulting in moderate (50%-74%) stenosis, while the rest had no evidence of residual ECA disease at the site of ECA endarterectomy. Over the post-operative period, sixteen (24.6%) ECA lesions and no occlusions were reported. The degree of ECA stenosis ranged from moderate to severe with PSVs ranging from 120 to 461 cm per second. All ECA lesions were ostial. Only 3 (18.7%) lesions were detected in the first nine months post operatively. Fifteen lesions were smooth and regular on duplex, while one had features of irregular residual stenosis. Eight (50%) were isolated ECA lesions, while the rest was associated with either ICA restenosis or occlusion.

CONCLUSION

ECA disease progression detected by Duplex ultrasound following eversion endarterectomy, as a part of CEA, commonly happens after 9 months and results in recurrent ECA stenosis, in most cases. Timing and features of the lesions suggest an intimal reaction as the aetiology in most cases. Eversion endarterectomy of the ECA does not predispose to ECA occlusion.

External Carotid Artery Stenting to Treat Patients With Symptomatic Ipsilateral Internal Carotid Artery Occlusion

BACKGROUND

The external carotid artery (ECA) anastomoses in many distal territories supplied by the internal carotid artery (ICA) and is an important source of collateral circulation to the brain. Stenosis of the ECA in ipsilateral ICA occlusion can produce ischemic sequelae.

OBJECTIVE

To examine the effectiveness of ECA stenting in treating symptomatic ipsilateral ICA occlusion.

METHODS

We retrospectively reviewed patient databases from 5 academic medical centers to identify all individuals who underwent ECA stenting after 1998. For all discovered cases, coinvestigators used a common submission form to harvest relevant demographic information, clinical data, procedural details, and follow-up results for further analysis.

RESULTS

Twelve patients (median age, 66 years; range, 45–79 years) were identified for our cohort. Vessel disease involvement included severe ECA stenosis ≥ 70% in 11 patients and ipsilateral ICA occlusion in all patients. Presenting symptoms included signs of transient ischemic attack, stroke, and amaurosis fugax. ECA stenting was associated with preservation of neurological status in 11 patients and resolution of symptoms in 5 patients at a median follow-up time of 26 months (range, 1–87 months; mean, 29 months). Symptomatic in-stent restenosis did not occur within any patient during the follow-up course.

CONCLUSION

We found ECA stenting in symptomatic ipsilateral ICA disease to be a potentially effective strategy to preserve neurological function and to relieve ischemic symptoms. Further investigation with larger studies and longer follow-up periods is warranted to elucidate the true indications of this management strategy.

External carotid artery angioplasty and stenting followed by superficial temporal artery to middle cerebral artery anastomosis

A 31-year-old man presented with right hemiparesis, and magnetic resonance imaging revealed a small infarct at left basal ganglia. Digital subtraction angiography showed left cervical internal carotid artery (ICA) occlusion and severe stenosis of the ipsilateral external carotid artery (ECA) with collateral cerebral circulation fed by ECAs. Based on the results of a functional evaluation of cerebral blood flow, we performed preventive ECA angioplasty and stenting for advanced ECA stenosis to ensure sufficient blood flow to the superficial temporal artery. Eight weeks later, superficial temporal artery to middle cerebral artery (STA-MCA) anastomosis was performed. His postoperative course was uneventful and no additional transient ischemic attacks have occurred. To our knowledge, this is the first report of preventive angioplasty and stenting for advanced narrowing of an ECA before STA-MCA anastomosis for ipsilateral ICA occlusion.

Fate of the external carotid artery following carotid interventions

OBJECTIVE

The external carotid artery (ECA) is an important collateral pathway for cerebral blood flow. Carotid artery stenting (CAS) typically crosses the ECA, while carotid endarterectomy (CEA) includes deliberate ECA plaque removal. The purpose of the present study was to compare the long-term patency of the ECA following CAS and CEA as determined by carotid duplex ultrasound.

METHODS

Duplex ultrasounds and hospital records were reviewed for consecutive patients undergoing CAS between February 2002 and April 2008, and were compared with those undergoing CEA in the same time period. Preoperative and postoperative ECA peak systolic velocities were normalized to the common carotid artery (CCA) as ECA/CCA ratios. A significant (80% or greater) ECA stenosis was defined as an ECA/CCA ratio of 4.0. A change of ratio by more than 1 was defined as significant. Data were analyzed using Student's t test and χ(2) analysis.

RESULTS

A total of 86 CAS procedures in 83 patients were performed (81 men, mean age 69.9 years). Among them, 38.4% of patients had previous CEA, 9.6% of whom had contralateral internal carotid artery occlusion. Sixty-seven CAS and 65 CEA patients with complete duplex data in the same time period were included in the analyses. There was no difference in the incidence of severe ECA stenosis on preoperative ultrasound evaluations. During a mean follow-up of 34 months (range four to 78 months), three postprocedure ECA occlusions were found in the CAS group. The likelihood of severe stenosis or occlusion following CAS was 28.3%, compared with 11% following CEA (P<0.025). However, 62% of CEA patients and 57% of CAS patients had no significant change in ECA status. Reduction in the patient's degree of ECA stenosis was observed in 9.4% of CAS versus 26.6% of CEA patients. Overall, immediate postoperative ratios of both groups were slightly improved, but there was a trend of more disease progression in the CAS group during follow-up.

CONCLUSION

CAS is associated with a higher incidence of post-procedure ECA stenosis. Despite the absence of neurological symptoms, a trend toward late disease progression of ECA following CAS warrants long-term evaluation.

External carotid endarterectomy followed by superficial temporal artery to middle cerebral artery anastomosis for internal carotid artery occlusion with advanced ipsilateral external carotid stenosis

OBJECTIVE

For patients with internal carotid artery occlusion with advanced narrowing of the ipsilateral external carotid artery (ECA), we performed preventive carotid endarterectomy (CEA) for the ECA stenosis before superficial temporal artery (STA) to middle cerebral artery (MCA) anastomosis for internal carotid artery occlusion.

METHODS

Between August 2002 and July 2005, we treated seven patients with such lesions, six men and one woman, ranging in age from 52 to 66 years (median, 60 yr). Before STA-MCA anastomosis, we performed preventive CEA for advanced ECA stenosis (>70%) to ensure sufficient blood flow to the STA. STA-MCA double anastomoses were performed more than 1 month after the CEA. Postoperative cerebrovascular complications and carotid restenosis were investigated.

RESULTS

All patients in the present series had an excellent postoperative course without cerebrovascular complications during either the CEA or STA-MCA anastomosis phase. Furthermore, no postoperative carotid restenosis occurred, and all STA-MCA anastomoses were patent during a mean follow-up period of 35.6 months.

CONCLUSION

The present study suggests that surgical management by external CEA followed by STA-MCA anastomosis is safe and effective for patients with internal carotid artery occlusion and advanced stenosis of the ipsilateral ECA.

The Fate of the External Carotid Artery after Carotid Artery Stenting. A Follow-up Study with Duplex Ultrasonography

OBJECTIVE

To evaluate the long-term effect of carotid angioplasty and stenting (CAS) of the internal carotid artery (ICA) on the ipsilateral external carotid artery (ECA).

SUBJECTS AND METHODS

We prospectively registered the pre- and post-interventional duplex scans obtained from 312 patients (mean age 70 years) who underwent CAS. Duplex scans were scheduled the day before CAS, 3 and 12 months post-procedurally and yearly thereafter, to study progression of obstructive disease in the ipsilateral ECA compared to the contralateral ECA. The duplex ultrasound criteria used to identify ECA stenosis >or=50% were Peak Systolic Velocities of >or=125 cm/s.

RESULTS

Preprocedural evaluation of the ipsilateral ECA demonstrated >or=50% stenosis in 32.7% of cases vs 30% contralateral. Both ipsilateral and contralateral 3 (1%) ECA occlusions were noted. After stenting 5 (1.8%) occlusions were seen vs 1% contralateral. No additional ipsilateral occlusions and 2 additional contralateral occlusions were noted at extended follow-up. The prevalence of >or=50% stenosis of the ipsilateral ECA (Kaplan-Meier estimates) progressed from 49.1% at 3, to 56.4%, 64.7%, 78.2%, 72.3%, and 74% at 12, 24, 36, 48, and 60 months respectively. Contralateral prevalences were 31.3%, 37.7%, 41.7%, 43.1%, 46.0%, and 47.2% respectively (p<0.001). Progression of stenosis was more pronounced in 234 patients (75%) with overstenting of the carotid bifurcation (p=0.004).

CONCLUSION

Our results show that significant progression of >or=50% stenosis in the ipsilateral ECA occurs after CAS. There was greater progression of disease in the ipsilateral compared with the contralateral ECA. Progression of disease in the ECA did not lead to the occurrence of occlusion during follow up.

Endovascular repair of symptomatic external carotid artery stenosis

The treatment of external carotid artery stenosis has been described with a variety of operative interventions. We present a patient who presented with amaurosis fugax and a critical left external carotid artery stenosis with known left internal carotid artery occlusion. We treated this stenosis with angioplasty and stenting rather than endarterectomy. Our patient did well and had no complications from the procedure. Endovascular repair of symptomatic external carotid artery stenosis provides an alternative treatment method to conventional endarterectomy for patients with high surgical risk.

Carotid endarterectomy in patients with chronic renal insufficiency: A recent series of 184 cases

BACKGROUND

The published results of carotid endarterectomy (CEA) in chronic renal insufficiency (CRI) patients are contradictory, mostly because of the relatively small number of patients in these studies. To better assess the neurologic complications and mortality, we reviewed a recent and substantially larger series of CRI patients who underwent CEAs.

METHODS

From March 2000 to March 2003, 675 consecutive primary CEAs were performed in 609 patients (346 men, 57%) under general anesthesia. Asymptomatic carotid artery stenosis accounted for 71% of cases. CRI (serum creatinine level > or = 1.5 mg/dL) was detected in 166 patients (27%) who underwent 184 CEAs. The remaining 443 patients (73%) had 491 CEAs.

RESULTS

Patients with CRI were different in age (76 +/- 8 years vs 72 +/- 9 years, P < .001), male gender (73% vs 51%, P < .001), coronary artery disease (50% vs 28%, P < .001), and diabetes mellitus incidence (38% vs 27%, P < .02). No significant difference in stroke rates was observed between the CRI patients and the control group (1.2% vs 0.5%). The mortality rate for CRI patients was 3%, whereas it was 0% for the control group ( P < .002). The 143 CRI patients with serum creatinine levels from 1.5 to 2.9 mg/dL had a 0.7% mortality rate, whereas it was 17% for 23 patients with serum creatinine levels of 3 mg/dL or more ( P < .001). The stroke rate for the former group was 0.7% and 4.3% for the latter group (NS). Asymptomatic (16) and symptomatic (7) patients with serum creatinine levels of 3 mg/dL or more had mortality rates of 13% and 28%, respectively, with P = .6.

CONCLUSION

The high mortality rate observed in patients with serum creatinine levels of 3 mg/dL or more after CEA calls for a nonoperative approach in the management of asymptomatic patients.

Particle-Hemodynamics Simulations and Design Options for Surgical Reconstruction of Diseased Carotid Artery Bifurcations

Based on the hypothesis that aggravating hemodynamic factors play a key role in the onset of arterial diseases, the methodology of “virtual prototyping” of branching blood vessels was applied to diseased external carotid artery (ECA) segments. The goals were to understand the underlying particle-hemodynamics and to provide various geometric design options for improved surgical reconstruction based on the minimization of critical hemodynamic wall parameters (HWPs). First, a representative carotid artery bifurcation (CAB) and then CABs with stenosed ECAs, i.e., a distally occluded ECA and an ECA stump, were analyzed based on transient three-dimensional blood flow solutions, employing a user-enhanced commercial finite volume code. Specifically, the HWPs, i.e., oscillatory shear index, wall shear stress angle gradient, near-wall residence time of monocytes, and near-wall helicity angle difference were evaluated to compare the merits of each design option, including a reconstructed near-optimal junction which generates the lowest HWP-values. The results provide physical insight to the biofluid dynamics of branching blood vessels and guide vascular surgeons as well as stent manufacturers towards interventions leading to high sustained patency rates.

Intraoperative carotid artery duplex scanning in a modern series of 650 consecutive primary endarterectomy procedures

PURPOSE

Thromboembolic complications after carotid endarterectomy are frequently associated with technical defects. We analyzed the effect of intraoperative duplex scanning in detection of significant but clinically unsuspected technical defects and residual common carotid artery (CCA) disease as a potential source of postoperative transitory ischemic attack (TIA) and stroke.

METHODS

From April 2000 to April 2003, 650 consecutive primary carotid endarterectomy procedures were performed in 590 patients at a single institution by two vascular surgeons. Patients included 335 men (57%) and 255 women (43%). Indications for surgery were asymptomatic internal carotid artery (ICA) stenosis (>or=70%) in 464 patients (71%). All procedures were performed with the patient under general anesthesia, with synthetic patch angioplasty in 644 (99.1%). Major technical defects at intraoperative duplex scanning (>30% luminal internal carotid artery stenosis, free-floating clot, dissection, arterial disruption with pseudoaneurysm) were repaired. CCA residual disease was reported as wall thickness (0.7-4.8 mm; mean, 1.7 +/- 0.7) and percent stenosis (16%-67%; mean, 32% +/- 8%) in all cases. Postoperative 30-day TIA, stroke, and death rates were analyzed.

RESULTS

There were no clinically detectable postoperative thromboembolic events in this series. All 15 major defects (2.3%) identified with duplex scanning were successfully revised. These included 7 intimal flaps, 4 free-floating clots, 2 ICA stenoses, 1 ICA pseudoaneurysm, and 1 retrograde CCA dissection. Diameter reduction ranged from 40% to 90% (mean, 67 +/- 16%), and peak systolic velocity ranged from 69 to 497 cm/s (mean, 250 +/- 121 cm/s). Thirty-one patients (5%) with the highest residual wall thickness (>3mm) in the CCA and 19 (3%) with the highest CCA residual diameter reduction (>50%) did not have postoperative stroke or TIA. Overall postoperative stroke and mortality rates were 0.3% and 0.5%, respectively; combined stroke and mortality rate was 0.8%. One stroke was caused by hyperperfusion, and the other occurred as an extension of a previous cerebral infarct. No patients had TIAs. Two deaths were caused by myocardial infarction, and one death by respiratory insufficiency.

CONCLUSION

We believe intraoperative duplex scanning had a major role in these improved results, because it enabled detection of clinically unsuspected significant lesions. Residual disease in the CCA does not seem to be a harbinger of stroke or TIA.

Effect of carotid artery stenting on the external carotid artery

OBJECTIVE

We studied the fate of the ipsilateral external carotid artery (ECA) after stenting of the internal carotid artery (ICA) compared with the contralateral ECA.

SUBJECTS AND METHODS

One hundred twenty-one ipsilateral ECAs in 112 consecutive patients who underwent carotid artery Wallstent placement were prospectively studied with color-coded duplex sonographic scanning (CCDS) and compared with 83 contralateral ECAs over 2 years. CCDS was scheduled for the day before (day 0), the day after (day 1) and 3, 6, 12, and 24 months after stenting. Development of ECA occlusive disease was evaluated with ECA-common carotid artery flow ratio (peak systolic velocity). For estimation of ECA stenosis 70% or greater, flow ratio 4.1 was used as the cutoff point.

RESULTS

Before and after stenting, two and three (one additional) ECA occlusions were seen. Median grade of ECA stenosis on day 1 did not significantly change at angiography (P = 1.0; tendency of increase) or CCDS (P =.27; tendency of decrease).At follow-up (day 1-24 months, CCDS only), frequency of stenosis 70% or greater in the ipsilateral ECA was 21 of 120 (17.5%) on day 1 and 41 of 107 (38.32%) at 24 months, and 3 of 107 (2.5%) and 5 of 107 (4.67%) ECA occlusions were registered at the two time points. Progression of disease, as demonstrated by increase in flow ratio over time, was much more pronounced in the ipsilateral ECAs compared with the contralateral ECAs (P =.0002). In stented ICA, 2 (1.85%) asymptomatic recurrent stenoses 70% or greater were found at CCDS. One of three patients with new ECA occlusions reported jaw claudication for 10 days. Perioperative stroke (one major, four minor) occurred in 5 of 121 patients (4.46%). Two minor strokes caused by embolization occurred during the first year.

CONCLUSION

The more pronounced progression of arteriosclerotic disease at the orifice of the ipsilateral ECAs during the first year after carotid stenting might be due to local factors of the ICA stent. Its clinical significance in respect to the effect of the ECA as collateral supply to the brain might depend on the incidence of carotid stent rerecurrent stenosis, which was low in the present study.

Computational analysis of effects of external carotid artery flow and occlusion on adverse carotid bifurcation hemodynamics

OBJECTIVE

This is a computational analysis of the effects of external carotid artery (ECA) flow, waveform, and occlusion geometry on two hemodynamic wall parameters associated with intimal hyperplasia and atherosclerosis. Study design Transient three-dimensional fluid mechanics analysis was applied to a standard carotid artery bifurcation. Mean internal carotid artery (ICA) flow was maintained at 236 mL/min with a normal waveform. ECA flow was increased from zero to 151 mL/min (64% of ICA flow) with both a normal biphasic waveform and a damped waveform. Geometry of five ECA occlusions was studied: distal, proximal stump, smooth, smooth without carotid sinus, and optimal reconstruction.Primary outcome measures Two time-averaged and area-averaged hemodynamic wall parameters were computed from the velocity and wall shear stress (WSS) solutions, ie, wall shear stress angle gradient (WSSAG) and oscillatory shear index (OSI). Both local and area-averaged hemodynamic wall parameters were computed for the distal common carotid artery (CCA) and the proximal ICA.

RESULTS

When ECA flow with a normal waveform is increased from zero to 151 mL/min, area-averaged WSS values increase in the CCA, from 3.0 to 4.4 dynes/cm(2) (46%), and in the ICA, from 16.5 to 17.1 dynes/cm(2) (4%); minimum local WSS values in the carotid sinus remain less than 1 dyne/cm(2); maximum local values of WSSAG and OSI are observed in the carotid sinus and increase from 3.5 to 9.1 radian/cm (160%) and 0.23 to 0.46 (100%), respectively; CCA plus ICA area-averaged WSSAG increases by 52%, and OSI increases by 144%; and damping of the ECA waveform has little effect on local or area-averaged WSSAG but reduces OSI to 68%. When the ECA is occluded, the minimum local WSS in the carotid sinus is less than 1 dyne/cm(2). However, if the carotid sinus is removed or the CCA-ICA geometry hemodynamically optimized, the minimum WSS is approximately 4 dynes/cm(2). Similarly, eliminating the carotid sinus markedly reduces local maximum WSSAG, from 3.0-3.5 radian/cm to 0.3 radian/cm, and reduces local maximum OSI from 0.22-0.49 to 0.04. Area-averaged WSSAG and OSI over the CCA and ICA are reduced by approximately 50% with elimination of the carotid sinus.

CONCLUSIONS

The degree of adverse carotid bifurcation hemodynamics as measured with WSSAG and OSI is directly proportional to ECA flow. The marked difference in normal ICA and ECA flow waveforms does not contribute to adverse wall hemodynamics. Location of an ECA occlusion (distal, proximal, stump, smooth) does not affect adverse carotid hemodynamics; however, marked improvement is obtained with elimination of the carotid sinus.

Carotid surgery without external carotid endarterectomy: a 6-year clinical experience with 1027 cases

PURPOSE

previously we routinely performed endarterectomy of the external carotid artery (ECA) during carotid surgery. However, discouraging experience and lack of supportive data in the literature made us question its necessity. The present report describes our experience with a modified carotid endarterectomy (CEA) technique where the ECA is left undisturbed regardless of its degree of stenosis.

METHODS

from January 1996 to June 2001, 1027 CEAs were performed in 905 patients with this technique at our institution. All operations were performed for at least 60% internal carotid artery (ICA) stenosis. A preoperative carotid duplex scan was available for review in 990 cases (96%). Follow-up duplex scans were recovered from 0 to 1 months in 851 cases (83%) and from >1 month in 655 cases (64%). Seventy percent of these cases were performed for asymptomatic lesions.

RESULTS

the perioperative (30-day) mortality rate for the entire group of patients was 0.5% and the stroke rate was 0.7%. Mean follow-up was 18 months (range: 2-66 months). Only two ECAs occluded in the first postoperative month. During the follow-up period, 37 additional ECAs (5.6%) were found to progress from mild to severe (>75%) stenosis postoperatively. In addition, 7% of the cases were found to have worsened the degree of stenosis, 8% improved and 85% remained unchanged.

CONCLUSION

these data support sparing of the ECA during CEA.

Cerebral hyperperfusion syndrome after carotid endarterectomy: predictive factors and hemodynamic changes

PURPOSE

It is believed that cerebral hyperperfusion syndrome (CHS) is caused by loss of cerebral autoregulation resulting from chronic cerebral ischemia and that factors including increased intraoperative cerebral blood flow, ipsilateral or contralateral carotid disease, and postoperative hypertension may cause CHS. We describe our experience with CHS, which diverges from published reports.

MATERIALS AND METHODS

From March 2000 to February 2002 we performed 455 carotid endarterectomy (CEA) procedures in 404 patients at our institution. CHS developed 1 to 8 days (mean, 3.2 +/- 2.5 days) postoperatively in 9 patients (2%), 6 women and 3 men, whose age ranged from 52 to 84 years (mean, 69 +/- 8 years). Indications for surgery in 8 patients without neurologic symptoms were ipsilateral internal carotid artery (ICA) stenoses ranging from 70% to 99% (mean, 80% +/- 7%); the remaining patient had an ipsilateral stroke, with good clinical recovery, 7 weeks before CEA. Only 1 patient had significant contralateral ICA stenosis (70%). However, 5 patients had undergone contralateral CEA within the previous 3 months. CHS symptoms were severe headache in 5 patients, seizures in 3 patients (1 stroke), and visual disturbance and ataxia in 1 patient. All 404 patients (455 cases) underwent intraoperative and early (2 weeks) postoperative carotid artery duplex scanning. The 9 patients with CHS also underwent carotid artery duplex scanning at the time of the neurologic event.

RESULTS

Mean intraoperative ICA volume flow (MICAVF) in the 9 CHS cases was not significantly different from that in the other 446 cases (170 +/- 47 mL/min and 182 +/- 81 mL/min, respectively). However, mean ICA volume flow (481 +/- 106 mL/min) and peak systolic velocity (PSV) (108 +/- 33 cm/s) for the 9 CHS cases measured at onset of symptoms were higher than those for the remaining 446 cases (267 +/- 87 mL/min and 80 +/- 26 cm/s, respectively) (P <.01). Of the 9 patients with CHS, only 3 had systolic blood pressures more than 160 mm Hg at onset of symptoms. Severity of ipsilateral and contralateral ICA stenoses was not significantly different between the 9 CHS cases and the remaining 446 cases.

CONCLUSIONS

These data do not corroborate the common belief that CHS occurs preferentially in patients with severe ipsilateral or contralateral carotid disease, increased intraoperative cerebral perfusion, or severe hypertension. Recently performed contralateral CEA (<3 months) appears to be predictive of CHS.

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

PURPOSE

Intraoperative duplex scanning (IDS) after carotid endarterectomy (CEA) has been shown to reliably identify major defects either by significant changes in peak systolic velocities or by B-mode imaging. To evaluate whether IDS could also predict postoperative strokes in technically flawless CEAs, we analyzed several hemodynamic parameters and correlated them with patient outcome.

METHODS

From March 2000 to February 2001, 226 consecutive primary CEAs were performed in 208 patients (120 men). Of these, 153 lesions were asymptomatic. General anesthesia and synthetic carotid artery patches were used routinely. Intraluminal shunts were used when internal carotid artery (ICA) back-pressures were <50 mm Hg (35% of cases). IDS consisted of B-mode and color-flow imaging and spectral analyses of the common, external, and internal carotid arteries. Volume flows were measured three times, and the mean flow rate was used for this study.

RESULTS

The first set of data was analyzed when the twenty-ninth patient had the second immediate postoperative stroke. It was noted that the two patients who had postoperative strokes had mean ICA volume flows (MICAVF) of 48 mL/min and 85 mL/min. Only two additional patients had MICAVF <100 mL/min. The remaining 25 cases had MICAVF ranging from 102 to 299 mL/min, with a mean of 165 +/- 57 mL/min (+/-SD) (P <.02). Although there was a significant correlation between MICAVF and ICA peak systolic velocity (P <.01), the latter was not found to be a significant predictor of postoperative stroke. Moreover, end-diastolic velocities, resistive index, ICA diameter, and ICA back-pressure also did not correlate with neurologic events. These findings led us to change our protocol for patients with MICAVF <100 mL/min. This included a repeat set of volume flow measurements after 15 to 20 minutes, withholding the reversal of heparin, and the liberal use of completion arteriography. Of the following 197 CEAs, 26 (13%) were found to have MICAVF <100 mL/min (range 55 to 99 mL/min; mean 79 +/- 18 mL/min). Of these, five had arteriography that documented spasm of the intracranial portion of the ICA in four and a small-diameter ICA (<2 mm) in one. Except for the five cases, the remaining 21 cases had MICAVF >100 mL/min (range 105 to 158 mL/min, mean 127 +/- 20 mL/min [+/-SD]) on repeat study. Four patients with persistent ICA low flow (70 to 99 mL/min) were treated with postoperative anticoagulation. One of the last 197 patients had a stroke caused by hyperperfusion syndrome 2 weeks after operation. Overall, six of 226 cases (2.7%) required revision on the basis of abnormal B-mode imaging results or peak systolic velocities >150 cm/s. There were two common carotid artery flaps, two ICA stenoses, one ICA flap, and one localized thrombus. All six were successfully revised and had repeat normal IDS study results, and none of these patients had a postoperative stroke.

CONCLUSIONS

IDS is helpful in identifying residual lesions or defects that may contribute to postoperative neurologic deficits. MICAVF <100 mL/min are suggestive of spasm that could lead to thrombus formation and stroke, particularly in the presence of synthetic patches. We suggest that heparin reversal should not be used unless ICA flow rates are >100 mL/min. ICA spasm is short lived in most patients undergoing CEA.

Influence of anatomical location on arterial thrombosis

Atherosclerosis manifests as a systemic disease with near global involvement of the named segments of the arterial tree. Acute thrombotic arterial occlusion, however, is not equally distributed. To evaluate intra-individual regional differences in arterial thrombogenicity, we compared (111)In-platelet deposition in porcine carotid and femoral arteries after a standardized crush injury. Within the unidirectional flow conditions of elastic carotid arteries, platelet deposition was more than 3-fold higher compared with predominantly muscular femoral arteries with triphasic arterial flow. To determine the influence of rheology on platelet deposition after crush injury, carotid arteries were transplanted into the femoral position and compared with the paired native carotid and femoral arteries. Similarly, femoral arteries transposed to the carotid position were compared with the paired native carotid artery. In each of these experiments, arterial transposition to a new anatomic location imparts a predilection for platelet deposition indigenous to the new location. In the controlled environment of two high-shear thrombin-independent and -dependent flow chambers, porcine carotid and femoral arterial substrates were indistinguishable from one another with respect to platelet deposition. Regional differences in arterial hemodynamics may account for substantial differences in thrombosis arising from deep arterial injury.

Changing characteristics of carotid endarterectomy

We have noted significant differences in terms of our preoperative work-up, length of stay, morbidity, and mortality of patients undergoing carotid endarterectomy (CEA) from findings reported in large published randomized clinical trials. To further investigate these differences, we have reviewed our recent experience. CEA has proved to be the most effective approach to avert stokes caused by significant atherosclerotic disease of the carotid bifurcation. Between January 1, 1996 and December 31, 1998, 552 patients underwent CEA at our institution. Forty percent were performed in symptomatic patients with stenotic lesions > 60% in diameter by duplex ultrasonography. The remainder were performed for asymptomatic lesions > 60% in diameter. No patient underwent contrast angiography. Fifty-two percent of the patients were males. The mean age was 74 +/- 8 years old. General anesthesia was used in 97% of the cases and regional block, in 3%. All patients underwent routine postoperative measurement of serum creatinine phosphokinase (CPK) isoenzymes. Patients were discharged when deemed clinically stable. The patients' follow-up visits at 1 week and at 3-5 months after the procedure (mean, 3.4 months) included a neurological exam and duplex exam. Patient results suggest that CEAs can be performed in the modern era without contrast arteriography. Most patients can be discharged on the first postoperative day. In addition, previously acceptable rates of postoperative morbidity and mortality should perhaps be revised to meet current standards. Contrary to the previous concept that most postoperative strokes are due to embolic phenomena, hyperperfusion syndrome played an increasingly important role in this review.

Use of intraoperative duplex ultrasonography and routine patch angioplasty in patients undergoing carotid endarterectomy

OBJECTIVE

To determine the value of routine patch angioplasty and intraoperative duplex ultrasonography (US) during carotid endarterectomy (CEA) for high-grade internal carotid artery stenosis.

PATIENTS AND METHODS

The charts of 102 consecutive patients who underwent CEA with routine patching and intraoperative duplex US for treatment of high-grade carotid stenosis between June 1991 and January 1997 were reviewed retrospectively. Recurrent stenosis was defined as a narrowing in the common or internal carotid artery of more than 40%.

RESULTS

Of 102 patients, 65 (63.7%) were men, and 37 (36.3%) were women (mean age, 72.4 years). Thirteen patients (12.7%) had bilateral CEAs. Intraoperative duplex US revealed abnormalities during 29 (25.2%) of 115 CEAs; 14 abnormalities (12.2%) were major and underwent immediate revision. No perioperative neurologic events or deaths occurred. Mean length of follow-up was 21.3 months (range, 1.3-72.6 months). Late neurologic events occurred in 2 patients, and 5 patients died during follow-up. All neurologic events and deaths were unrelated to the patients' carotid surgery. Twelve patients (11.8%) developed moderate restenosis (40%-69%). In 4 of these patients restenosis resolved during further follow-up. No patient developed severe recurrent carotid stenosis.

CONCLUSION

Morbidity and mortality following CEA with routine patch angioplasty and intraoperative duplex US appear to be low. Routine intraoperative duplex US detects correctable technical problems that subsequently lead to a low incidence of symptomatic stenosis. The low incidence of recurrent stenosis suggests that routine postoperative follow-up may not be necessary or cost-effective unless the patient has symptoms or a contralateral stenosis.

The outcome of external carotid endarterectomy during routine carotid endarterectomy

PURPOSE

This study is an analysis of the outcome of a common method of management of the external carotid artery (ECA) during routine carotid endarterectomy (CEA).

METHODS

Between 1986 and 1997, 1069 primary CEAs were performed with a combination of proximal eversion technique and blind distal endarterectomy on the ECA. Of these, 973 CEAs (91%) had 1 or more postoperative duplex scans that included the ECA. Both preoperative and early postoperative studies were performed on 313 of these CEAs. Intraoperative post-CEA continuous-wave Doppler scans identified low flow or occlusion of the ECA in 37 CEAs (4%). These ECAs were isolated and repaired.

RESULTS

The early post-CEA duplex scan velocities were 143 +/- 81 cm/s (mean +/- 1 standard deviation of the mean). In the first 6 months after the CEAs, 692 ECAs (72%) had <50% stenosis, 175 (18%) had 50% to 74% stenosis, 90 (9%) had > or =75% stenosis, and 9 (1%) were occluded. Of the 37 repaired ECAs, 20 (54%) had <50% stenosis, 10 (27%) had 50% to 74% stenosis, 5 (14%) had > or =75% stenosis, and 2 (5%) were occluded. The cumulative life-table > or =50% stenosis rate was 36% at 1 year, 40% at 3 years, 48% at 5 years, and 81% at 10 years. The cumulative > or =75% stenosis rate was 12% at 1 year, 12% at 3 years, 15% at 5 years, and 37% at 10 years. Preoperative studies showed <50% stenosis in 152 of the 313 ECAs (48%). In the early postoperative period, 102 of these ECAs (66%) had <50% stenosis, 35 (23%) had 50% to 74% stenosis, 13 (9%) had > or =75% stenosis, and 3 (2%) were occluded. Of the 161 ECAs with > or =50% preoperative stenosis, 66 (41%) had <50% stenosis in the first 6 months after CEA, 61 (38%) had 50% to 74% stenosis, 32 (20%) had > or =75% stenosis, and 2 (1%) were occluded.

CONCLUSIONS

Combined proximal eversion technique and blind distal ECA endarterectomy during routine CEA gives poor and unacceptable early and late outcomes. The repair of severely obstructed or occluded ECA identified during surgery after CEA has a similarly poor outcome. The technique and management of the ECA during routine CEA needs further investigation and modification.

Completion angiography, is it really necessary?

BACKGROUND

Routine completion imaging after carotid endarterectomy (CEA) has been advocated by many investigators to detect and repair unsuspected defects with the goal of reducing perioperative morbidity and residual disease. However, completion imaging has been performed rarely in our practice. Our carotid registry was interrogated to determine whether omitting routine completion imaging adversely affected outcome.

METHODS

A retrospective review of 229 consecutive CEAs performed by one vascular surgeon during 1988 to 1996 was completed. Duplex follow-up was used to identify persistent residual defects, which were classified as 50% to 74%, 75% to 99%, and occlusion in the common (CCA), internal (ICA), and external (ECA) arteries and was available in 192 cases.

RESULTS

During the study period, eight completion angiograms were performed (3.5%) and 5 arteries were reopened. Combined stroke and death rate was 3.1% (7 of 229). Duplex follow-up, available on 192 patients, showed residual lesions in 29 patients (15%), but only 7 (3.6%) involving the internal or common carotid.

CONCLUSION

Routine completion imaging is not required to achieve acceptable morbidity and mortality and minimize residual problems after CEA. Attention to operative details with selective imaging will give excellent results.