Efficacy of a proximal occlusion catheter with reversal of flow in the prevention of embolic events during carotid artery stenting: an experimental analysis

OBJECTIVE: The role of percutaneous angioplasty and stenting of carotid bifurcation lesions has been limited by its potential for producing embolic debris. We evaluated the efficacy of a proximal occlusion catheter (POC) in the prevention of embolic events during carotid artery stenting. In addition, pressure measurements relevant to the clinical application of this device were obtained from 10 patients undergoing carotid endarterectomy. METHODS: The POC is a guiding catheter with an occlusion balloon attached on the outside of the catheter at its distal end. Occlusion of the common carotid artery (CCA) was achieved by inflating the balloon while access to carotid bifurcation lesions was obtained through the inner lumen. The POC was inserted in the CCA of 10 dogs via the femoral artery. The side port of the POC was connected to a sheath placed in the femoral vein, thereby creating an external arteriovenous shunt. Ten artificial radiopaque particles simulating embolic particles and contrast agent were introduced in the CCA and monitored fluoroscopically. As a control, the same procedure was performed with a standard guiding catheter without an occlusion balloon. In 10 patients undergoing carotid endarterectomy, the internal carotid artery (ICA) and external carotid artery stump pressures and the pressure in the internal jugular vein were measured. RESULTS: Without the external arteriovenous shunt, in all animals there was prograde flow in the distal CCA despite CCA occlusion. This flow was derived from the thyroid artery. However, once the arteriovenous shunt was activated, reversal of flow in the distal CCA was achieved in each animal, and all the artificial particles were recovered from the side port of the POC. In the control group, each particle embolized to the brain (100%, P <.01). In the patients, the mean stump pressures in the ICA and external carotid artery and the jugular vein pressure were 51.8 +/- 14.2, 62.2 +/- 15.1, and 6.5 +/- 3.5 mm Hg, respectively. In each case, the jugular vein pressure was the lowest among the three. CONCLUSIONS: Obtaining proximal CCA control by inflating the POC does not sufficiently prevent embolization. However, reversal of flow in the ICA can always be created with the external shunt, which effectively prevents embolization. Thus, POC may markedly lower procedural stroke rates during carotid artery stenting. The ability of POC to prevent embolization before crossing the lesion with a guidewire may be an important advantage over other distal protection devices.     

Cerebral protection during retrograde carotid artery stenting for proximal carotid artery stenosis: technical note

Carotid artery stenting for carotid bifurcation stenosis usually uses the transfemoral approach. However, in patients with proximal common carotid artery (CCA) stenosis, the guiding catheter is difficult to introduce into the narrow origin of the CCA without risking cerebral embolization before activation of the protection device. A technique of cerebral protection by internal carotid artery (ICA) clamping with or without simultaneous external carotid artery (ECA) clamping was used to treat patients with proximal CCA stenosis by the retrograde direct carotid approach. The carotid bifurcation was surgically exposed and retrograde catheterization was performed to approach the stenosis. The ICA was clamped during angioplasty and stenting to avoid cerebral embolization. The ECA was clamped simultaneously if any extracranial-intracranial anastomosis was present. None of five patients treated with this technique experienced ischemic complications attributable to this technique.     

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.     

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.

The haemodynamic value of external carotid artery collateral blood supply in carotid artery disease

In the presence of severe obstruction of the internal carotid artery (ICA) blood supply to the ipsilateral hemisphere may be provided by collaterals. Whereas the circle of Willis in many cases makes a substantial contribution to cerebral perfusion, the value of collateral blood supply originating from the external carotid artery (ECA) is not clear. In thirty-five patients undergoing carotid endarterectomy (24 with proven external carotid artery collaterals) intra-arterial blood pressures were measured across the ICA stenosis, prior to endarterectomy. In order to evaluate the haemodynamic value of ECA collaterals, the distal ICA pressure was measured with and without the ECA clamped. In addition, volume blood flow in the common carotid artery was measured with and without the ECA clamped, before and after endarterectomy. No significant change in distal ICA pressure was observed when the ECA was clamped, whether or not external carotid artery collaterals had been demonstrated preoperatively. The greatest reduction in mean distal ICA pressure observed upon ECA clamping was 8 mmHg. However, this only occurred in three of 11 patients with a severe pressure reduction across the stenosis. ICA blood flow increased significantly following endarterectomy whereas ECA flow was reduced. This study indicates that ECA collaterals in most cases do not contribute substantially to cerebral perfusion. Endarterectomy of the ECA, in order to improve cerebral circulation, seems justified only in selected cases, where the distal ICA pressure has been shown to be severely reduced.     

Carotid angioplasty with internal carotid artery flow reversal is well tolerated in the awake patient

OBJECTIVE: The purpose of this study was to evaluate the neurologic tolerance and changes in ipsilateral hemispheric oxygen saturation during transcervical carotid artery stenting with internal carotid artery (ICA) flow reversal for embolic protection. PATIENTS AND METHODS: This was a prospective study of 10 patients (mean age 68 years) undergoing transcervical carotid angioplasty and stenting. All ICA stenoses were greater that 70%. Seven patients had an ipsilateral hemispheric stroke (3) or transient ischemic attack (4), two patients had a contralateral stroke, and one patient was asymptomatic. Nine procedures were done under local anesthesia. Cerebral protection was established through a cervical common carotid (CCA) cutdown to create an external fistula between the ICA and the internal jugular vein with temporally CCA occlusion. Venous oxygen saturation (SVO(2)) was continuously monitored through a catheter placed in the distal internal jugular vein. Mental status and motor-sensory changes were categorized and assessed throughout and after the procedure. RESULTS: All procedures were technically successful without significant residual stenosis. Mean ICA flow reversal time was 22 minutes (range, 15 to 32). Common carotid artery (CCA) occlusion produced a slight (SVO(2) = 72.6%+/-9.4) but significant decrease (P =.012) in SVO(2), compared with baseline (SVO(2) = 77% +/-10.5). During ICA flow reversal (SVO(2) = 72.4% +/-10.1) cerebral oxygen saturation did not change compared with CCA occlusion alone (P =.85). Transient balloon occlusion during angioplasty of the ICA (SVO(2) = 64.6%+/-12.9) produced a significant decrease in cerebral SVO(2) compared with CCA occlusion (P =.015) and compared with CCA occlusion with ICA flow reversal (P =.018). No mental status changes or ipsilateral hemispheric focal symptoms occurred during CCA occlusion with ICA flow reversal. One patient with contralateral ICA occlusion sustained brief upper extremity weakness related to the contralateral hemisphere. Five patients sustained a vasovagal response during balloon dilatation, four did not require treatment, and one had asystole requiring atropine injection. Mean SVO(2) saturation was not different in these five patients compared with the five who did not sustain a vasovagal response. No deaths or neurologic deficits occurred within 30 days after the procedure. CONCLUSIONS: Our data suggest that transcervical carotid angioplasty and stenting with ICA flow reversal is well tolerated in the awake patient, even in the presence of symptomatic carotid artery disease. Cerebral oxygenation during ICA flow reversal is comparable to that during CCA occlusion. ICA angioplasty balloon inflation produces a decrease in cerebral SVO(2) significantly greater than that occurring during ICA flow reversal.     

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.     

Protection of anastomotic pathways to the vertebral artery during stenting of external carotid artery stenosis

A 61-year-old man presented with a severe external carotid artery (ECA) stenosis with concomitant ipsilateral internal carotid artery (ICA) occlusion manifesting as amaurosis fugax. The left ophthalmic artery was supplied from the left ECA. The left intracranial ICA was supplied by the collateral flow from the contralateral ICA and ipsilateral ECA through the ophthalmic artery. The left vertebral artery also participated in the latter collateral pathway through the left occipital artery and ascending pharyngeal artery. Percutaneous revascularization of the ECA was performed using a nitinol self-expanding stent. To prevent embolic complications through the ophthalmic or vertebral arteries, distal protection was performed using a balloon. During a 22-month follow-up period, the patient was completely free from any ocular or neurological symptoms. The present case of severe ECA stenosis with ipsilateral ICA occlusion showed that percutaneous balloon angioplasty with stenting is feasible and effective. This intervention requires cautious evaluation of the anastomotic pathways connecting the ECA to the cerebral circulation to avoid embolic complications.     

Common carotid occlusion for unclippable carotid aneurysms: an old but still effective operation

We present a selected series of nine patients with unclippable internal carotid artery aneurysms to illustrate our current approach to this problem. Eight of the nine underwent common carotid ligation after preoperative angiographic evaluation. Tolerance to carotid occlusion was determined intraoperatively by awake examination, electroencephalogram (EEG) monitoring, and carotid stump pressure measurements. No patient developed a permanent deficit; seven of eight treated aneurysms have thrombosed. Our experience and review of the literature indicate that most ischemic complications after carotid ligation seem to be thromboembolic, rather than due to "low flow" from poor collateral circulation. For this reason, we have gradually come to favor common carotid (CCA) over internal carotid (ICA) occlusion in many of these patients. After CCA occlusion, the ICA frequently remains open and embolic complications are therefore less likely. An extracranial-intracranial bypass procedure is performed only in those patients with poor collateral circulation demonstrated by cross compression angiographic studies, by the development of new deficits during test occlusion, or by the appearance of EEG changes during test occlusion. We suggest that CCA ligation remains a useful alternative in the management of unclippable internal carotid aneurysms.     

Surgical management of acute complications and critical restenosis following carotid artery stenting

Carotid artery angioplasty with stenting (CAS) is being increasingly used in the treatment of extracranial carotid artery stenosis. As in other catheter-based approaches to the treatment of arterial disease, surgical intervention may be required because of either acute complications or correct critical restenosis. We have reviewed our experience managing early complications and critical in-stent restenoses after CAS in a tertiary care university hospital and a Veterans Affairs Medical Center. During the last 5 years, 22 carotid arteries (21 patients) underwent CAS. One patient developed thrombosis and rupture of the carotid artery during stenting. Two other patients (3 arteries) developed critical restenosis within 12 months. Subsequent surgical reconstructions included an internal carotid artery (ICA)–to–external carotid artery (ECA) transposition and a common carotid artery (CCA)–to–ICA bypass with reversed saphenous vein (RSV). The patient who underwent CCA–to–ICA bypass later required subclavian–to–ICA bypass because of rapidly progressive intimal hyperplasia and subsequent occlusion of the CCA. The other patient has not had surgical repair because of his deteriorating condition and significant co-morbidities. During the same time period, two additional patients were referred from outside institutions specifically for surgical intervention after carotid stenting. One had delayed rupture of the carotid artery 1 day after stenting and underwent urgent surgical repair. Another patient had early, critical restenosis within the stent and underwent placement of a CCA–to–ICA interposition graft using RSV. Acute treatment failures after CAS can be successfully managed using standard surgical techniques. Patients who develop critical in-stent restenosis requiring surgical repair may need more challenging surgical reconstructions to maintain cerebral perfusion.     

Influence of poststenotic collateral pressure on blood flow velocities within high-grade carotid artery stenosis: differences between morphologic and functional measurements

PURPOSE: The driving force for blood flow through a high-grade stenosis in the internal carotid artery can be expressed as the pressure gradient over the stenosis itself, which, however, might be reduced by the back pressure exerted by distal collateral vessels. Theoretically the maximum blood flow velocity as a measure of the functional grade of obstruction may therefore be lower than what is expected from morphologic gradations of the stenosis. This study was designed to test prospectively the influence of intracranial collateral vessels on blood flow velocities within high-grade internal carotid artery stenoses. PATIENTS AND METHODS: Forty-five consecutive patients (age 66 +/- 11) with high-grade internal carotid artery stenoses were investigated before and during carotid endarterectomy. The preoperative investigations included duplex ultrasound scanning of the neck vessels, transcranial Doppler scanning for assessment of collateral flow to the middle cerebral artery and angiography. Carotid endarterectomy was performed with patients under deep general anesthesia without a shunt. Systolic and diastolic internal carotid artery blood pressures were measured before and during intraoperative cross-clamping (ie, stump pressure) of the carotid arteries. RESULTS: Within high-grade internal carotid artery stenoses, maximum systolic and end-diastolic blood flow velocities showed a significant inverse correlation to the corresponding systolic and diastolic stump blood internal carotid artery blood pressures. All patients with spontaneous collateral flow to the ipsilateral anterior part of the circle of Willis were divided into a group with relatively high and another one with low end-diastolic blood flow velocities. The stump pressure was significantly lower in patients with high end-diastolic blood flow velocities in spite of the fact that the mean angiographic grade of stenosis did not differ significantly between the groups. CONCLUSIONS: Flow velocities within a high-grade internal carotid artery stenosis are inversely dependent on the stump pressure, that is the poststenotic collateral perfusion pressure. This should be taken into consideration in case of discrepancies between angiography and ultrasound outcome.     

Correlation of postoperative and two-year follow-up angiography with neurological function in 99 carotid endarterectomies in 86 consecutive patients.

Eighty-six consecutive patients in 1982 underwent 99 endarterectomies and routine postoperative digital subtraction angiography. Ten vessels were closed primarily and 89 with a patch graft. Minor morbidity was 2%, major morbidity 0%, and mortality 1%, but these varied according to the patient's preoperative medical and neurological function and angiographic findings. Postoperative patency for the common carotid artery (CCA) and internal carotid artery (ICA) was 100% and for the external carotid artery (ECA) 97%. Seventy-nine vessels were evaluated by a DSA 2 years after surgery. There was one asymptomatic occlusion in follow-up and one symptomatic re-stenosis in a patient with a proven heparin induced hypercoagulability state. The three postoperative ECA occlusions were associated with a lethal postoperative stroke, the only ICA occlusion in follow-up, and a 50% stenosis of the CCA in follow-up at the site of ECA occlusion. Vein patch grafting protected the ICA but not the CCA from recurrent stenosis. The carotid slim sign on preoperative angiograms is judged to indicate a patient at high risk of stroke morbidity.     

The contribution of the external carotid artery to cerebral perfusion in carotid disease

PURPOSE: In the presence of carotid occlusion, the external carotid artery (ECA) becomes an important source of cerebral blood flow, especially if the circle of Willis is incomplete. The contribution of the ECA to hemispheric blood flow in patients with severe ipsilateral carotid stenosis has never been previously investigated. METHODS: One hundred eight patients were monitored during sequential cross-clamping of the external (ECA) and then ipsilateral internal carotid artery (ICA) during carotid endarterectomy using transcranial Doppler sonography (TCD) (Neuroguard CDS, Los Angeles, Calif), to measure middle cerebral artery blood flow velocity, and near-infrared spectroscopy, to measure regional cerebral oxygen saturation (CsO(2)) (Invos 3100A; Somanetics, Troy, Mich). RESULTS: On the ipsilateral ECA cross-clamp, the median fall in CsO(2) was 3% (interquartile range, 1%-4%; P <.0001). On addition of the ICA cross-clamp there was a further fall of 3% and a total fall of 6% (3%-9%; P <.0001). The median percentage fall in middle cerebral artery blood flow velocity on ECA clamping was 12% (4%-24%; P <.0001); on ICA clamping it was 48% (25%-74%; P <.0001). Falls in TCD on ECA clamping were greater with increasing severity of ipsilateral ICA stenosis. The correlation between CsO(2) and TCD on external clamping, although less strong than that on internal clamping, was statistically significant r = 0.32; P =.01; Spearman rank correlation). CONCLUSIONS: The falls in TCD and CsO(2) were of a similar order of magnitude and must therefore reflect a fall in cerebral perfusion. The ipsilateral ECA contributes significantly to intracranial blood flow and oxygen saturation in severe carotid stenosis.     

Dynamic cerebral autoregulation in carotid stenosis before and after carotid stenting

BACKGROUND: Impaired dynamic cerebral autoregulation (DCA) has been shown in patients with severe (> or =70%) internal carotid artery (ICA) stenosis, but DCA in moderate (50% to 69%) ICA stenosis, especially its response to carotid revascularization, has rarely been reported. Our study aimed to characterize DCA in severe and moderate ICA stenosis before and after carotid stenting. METHODS: This study included 21 patients with ICA stenosis > or =50% who received carotid stenting. Data of arterial blood pressure and cerebral blood flow velocity of the middle cerebral artery, measured by transcranial Doppler, were collected for 10 minutes < or =24 hours before and after stenting. The DCA index, represented as aMx, was assessed by calculating the Pearson product-moment correlation coefficient of spontaneous arterial blood pressure and cerebral blood flow velocity fluctuations. The relationship between aMx and stenotic severity and also alternations of aMx before and after stenting were assessed. RESULTS: Carotid stenting was effective to improve the DCA in the stenting side but not in the contralateral nonstenting side. In considering individual ICAs, the average aMx (mean +/- SD) increased significantly from ICA stenosis <50% (0.117 +/- 0.091) to 50% to 69% (0.349 +/- 0.144), 70% to 99% (0.456 +/- 0.147), and total occlusion (0.557 +/- 0.210; P < .05, P < .01, and P < .01, compared with 50% to 69%, 70% to 99%, or total occlusion with <50% stenosis). The correlation between the degree of ICA stenosis and the aMx was also significant (r = 0.693, P < .005). The aMx improved significantly in the stented side after carotid stenting in both moderate and severe ICA stenosis, and this finding was not affected by age, sex, risk factors, or clinical symptoms. CONCLUSIONS: In addition to patients with severe carotid stenosis, patients with moderate carotid stenosis may also have impaired DCA that can be restored after carotid stenting.     

Classification of carotid bifurcation disease using quantitative Doppler spectrum analysis

Spectrum analysis of continuous-wave Doppler recordings from the region of the carotid bifurcation was used to classify the degree of stenosis in the internal (ICA) and external (ECA) carotid arteries. Measurements of systolic peak frequency, end-diastolic frequency, and the degree of spectral broadening were used to define five ICA disease categories: 0% to 15% diameter reduction (DR), 16% to 49% DR, 50% to 80% DR, greater than 80% DR, and occlusion. The results were compared to contrast arteriography in 122 patients (243 arteries). The agreement with angiography in classifying ICA stenosis was 82%. Doppler spectrum analysis identified 96% of hemodynamically significant disease (greater than 50% DR) in the ICA and ECA and 97% of ICA occlusions. Attention to the common carotid artery waveform and the ICA diastolic frequency improved the accuracy of predicting greater than 80% DR and occlusion of the ICA. Noninvasive classification of carotid bifurcation disease is useful in clinical decision making to select the angiographic technique most likely to accurately define disease morphology and to follow up patients for disease progression.     

One patent intracranial collateral predicts tolerance of flow reversal during carotid angioplasty and stenting

Internal carotid artery (ICA) flow reversal is an effective means of cerebral protection during carotid stenting. Its main limitation is that in the absence of adequate collateral flow it may not be tolerated by the patient. The purpose of this study was to determine if preoperative identification of intracranial collaterals with computerized tomographic (CTA) or magnetic resonance (MRA) angiography can predict adequate collateral flow and neurological tolerance of ICA flow reversal for embolic protection. This was a study of patients undergoing transcervical carotid angioplasty and stenting. Neuroprotection was established by ICA flow reversal. All patients underwent preoperative cervical and cerebral noninvasive angiography with CTA or MRA and had at least one patent intracranial collateral. Mean carotid artery back pressure was measured. Neurological changes during carotid clamping and flow reversal were continuously monitored with electroencephalography (EEG). Thirty-seven patients with at least one patent intracranial collateral on brain imaging with CTA or MRA were included. Mean carotid artery back pressure was 58 mm Hg. All procedures were technically successful. No EEG changes were present with common carotid artery occlusion and ICA flow reversal. One patent intracranial collateral provides sufficient cerebral perfusion to perform carotid occlusion and flow reversal with absence of EEG changes. Continued progress in noninvasive imaging modalities is becoming increasingly helpful in our understanding of cerebral physiology and selection of patients for invasive carotid procedures.     

Direct and primary carotid endarterectomy for common carotid artery occlusion. Report of 2 cases

BACKGROUND: Cerebral ischemia associated with chronic CCA occlusion is a rare condition and raises strategic dilemma when the revascularization is needed. METHODS: Two patients with CCA occlusion presented with ischemic symptom associated with the affected side. Both patients underwent vascular reconstruction by direct carotid endarterectomy to achieve primary restoration of CCA to ICA flow. RESULTS: Successful reopening of the vessels was obtained in both patients without the evidence of postsurgical ischemic event. Follow-up MRA was obtained at later than 6 months after surgery, which demonstrated patent CCA-ICA in both patients. CONCLUSIONS: Direct carotid endarterectomy of the occluded CCA can be safely performed if the preoperative angiography suggest still patent vessels distal to carotid bifurcation and the substantial "back flow" is obtained from ICA during arteriotomy.     

High diastolic flow velocities in severe internal carotid artery stenosis: a sign of increased surgical risk?

PURPOSE: We reviewed the history and preoperative investigations of patients with early postoperative neurologic events after carotid thromboendarterectomy in an attempt to identify risk factors for neurologic complications. METHODS: Patients with neurologic events/complications (S group, n = 14 patients) were compared with an age- and disease-matched control group (C group, n = 42 patients) selected from the whole carotid thromboendarterectomy material between 1987 and 1996. In this retrospective study, we re-evaluated the maximum systolic and end diastolic flow velocities within the internal carotid artery (ICA) using video recordings of preoperative Duplex ultrasound scan investigations. The flow velocity variables were compared with preoperative carotid angiography and intraoperative ICA stump pressure measurement. RESULTS: S-group did not differ from C-group concerning either cardiovascular risk factors or diseases, ipsilateral and contralateral angiographic grade of ICA stenosis, or history of cerebral infarctions. Nevertheless, in contrast to control subjects, patients with early postoperative major stroke had higher end diastolic flow velocities and lower ICA stump pressures. Patients with postoperative minor stroke, transient ischemic attack, or amaurosis fugax did not differ significantly from the control subjects. Among patients with ICA stenosis of 75% or more, end diastolic flow velocities were correlated to the diastolic stump pressures. CONCLUSION: Diastolic flow velocities within severe internal carotid artery stenosis are dependent on the level of the collateral perfusion pressure distally to the stenosis (ie, high values indicate a low internal carotid artery stump pressure), which seems to be a risk factor for early postoperative strokes.     

Endovascular treatment of carotid blowout syndrome: who and how to treat

Carotid blowout syndrome (CBS) is a high-risk condition associated with significant morbidity and mortality that may result from invasion and destruction of the cervical carotid vasculature from head and neck squamous cell carcinoma. Endovascular approaches offer multiple modalities for treatment to prevent morbidity and death. In this paper we review our experience in addressing CBS and present an up-to-date algorithm of endovascular management. 16 lesions were identified in 8 patients treated with 9 procedures over the past year. Pseudoaneurysm and/or active extravasation were documented in at least one vessel in all 8 cases presenting with acute CBS. There were 13 pseudoaneurysms in external carotid artery (ECA) trunk (5), ECA branches (4), internal carotid artery (ICA) (1) and common carotid artery (CCA) (3). There were 3 additional ICA lesions due to tumor infiltration, resulting in ICA occlusion (2) and long segment stenosis (1). Permanent vessel occlusion was performed in 11 lesions of the ECA trunk (4), ECA branches (4) and ICA (3). Stent-grafts were placed in 5 lesions in the CCA (3), ICA (1) and ECA trunk (1). Technical success and immediate hemostasis were achieved in all patients. There were no procedural deaths or immediate complications. With a median follow-up of 2 months (range, 1-13 months), three patients died: one from recurrent CBS, one from global brain ischemia after a cardiac arrest event unrelated to CBS and one from systemic disease. There was no other recurrence of bleeding or neurological complication. Endovascular techniques offer an armamentarium to effectively address CBS, significantly affecting the care and outcome in this particular oncologic population. These techniques should be offered as early as possible in the context of a multidisciplinary approach.     

Common carotid occlusion. Assessment of the distal vessels

In patients with common carotid artery (CCA) occlusion, successful vascular reconstruction can be performed if there is a patent internal or external carotid distal to the occlusion. Preoperative selection of suitable candidates is often difficult because of the inability to visualize patent distal vessels with conventional angiography. In reviewing 24 patients operated upon for CCA occlusion since 1962, the distal internal or external carotid arteries were visualized in only four (17%) of the preoperative angiograms. When these 24 patients were explored, the internal carotid was found to be patent in 11 (46%) patients and the external patent in 15 (62%) cases. Of the 15 patients reconstructed, thromboendarterectomy was performed in six and saphenous vein bypass in nine. In the remaining nine patients, exploration revealed both the internal and external carotids to be thrombosed and unsuitable for CCA reconstruction. Recently we have used rapid sequential computerized tomography (RSCT) scanning to aid in the evaluation of the nonvisualized internal carotid artery (ICA). In two patients with CCA occlusion, RSCT correctly diagnosed patency of the ICA although it appeared to be occluded on angiography. Preliminary data suggest that RSCT will permit accurate preoperative selection of those CCA occlusion patients who are suitable surgical candidates and eliminate the need for surgical exploration.