Contralateral stenosis and stump pressures: parameters to identify the high risk patient undergoing carotid endarterectomy under local anaesthesia

Local Anesthesia in Carotid Angioplasty

Purpose:

To determine the safety and efficacy of local anesthesia for percutaneous carotid angioplasty and stenting performed via a direct common carotid access.

Methods:

Deep cervical plexus blockade was used for anesthesia in 22 of 32 patients (26 males; mean age 66 years) undergoing percutaneous carotid balloon angioplasty and/or stenting via direct carotid puncture. Local anesthesia was selected according to patient preference (n = 9); advanced age (n = 4); ischemic heart disease (n = 4); intended extracorporeal circulation for unstable angina (n = 3); and an incompetent circle of Willis (n = 2). The technique involved injection of bupivacaine hydrochloride along the C2, C3, and C4 transverse processes. No superficial cervical plexus blockade was used.

Results:

No complications of anesthesia were observed, though there were cases in which surgery became necessary under local anesthesia for angioplasty-related complications. These conversions were accomplished without difficulty.

Conclusions:

Cervical nerve blockade appears to be a safe and effective anesthetic method for endovascular carotid interventions performed percutaneously through direct carotid puncture.

Surgical Outcomes for Cervical Carotid Artery Stenosis: Treatment Strategy for Bilateral Cervical Carotid Artery Stenosis

BACKGROUND

Carotid endarterectomy (CEA) and carotid stenting (CAS) are beneficial procedures for patients with high-grade cervical carotid stenosis. However, it is sometimes difficult to manage patients with bilateral carotid stenosis. To decide the treatment strategy, one of the most important questions is whether contralateral stenosis increases the risk of patients undergoing CEA.

METHODS

This retrospective study included 201 patients with carotid stenosis who underwent a total of 219 consecutive procedures (CEA 189/CAS 30). We retrospectively analyzed outcomes in patients with carotid stenosis who were treated with either CEA or CAS and evaluated whether or not contralateral lesions increases the risk of patients undergoing CEA or CAS. Furthermore, we retrospectively verified our treatment strategy for bilateral carotid stenosis.

RESULTS

The incidences of perioperative complications were 5.3% in the CEA patients and 6.7% in the CAS patients, respectively. There was no significant difference between these 2 groups. The existences of contralateral occlusion and/or contralateral stenosis were not associated with perioperative complications in both the groups. There were 32 patients with bilateral severe carotid stenosis (>50%). Of those, 13 patients underwent bilateral revascularizations; CEA followed by CEA in 8, CEA followed by CAS in 3, CAS followed by CEA + coronary artery bpass grafting in 1, and CAS followed by CAS in 1.

CONCLUSIONS

Our date showed that the existence of contralateral carotid lesion was not associated with perioperative complications, and most of our cases with bilateral carotid stenosis initially underwent CEA.

Treatment strategy for bilateral carotid stenosis: 2 cases of carotid endarterectomy for the symptomatic side followed by carotid stenting

Since the introduction of carotid stenting (CAS), a combined treatment for bilateral lesions using carotid endarterectomy (CEA) and CAS has been developed. However, there has been only 1 report about CEA then CAS. Herein we describe 2 patients with bilateral severe carotid stenosis who were treated by CEA for the symptomatic side and CAS for the contralateral asymptomatic side. A 71-year-old man underwent CEA for the symptomatic side. Although the patient suffered hyperperfusion syndrome after CEA, he recovered fully after 3 weeks of rehabilitation. Two months later, CAS was performed for the asymptomatic side, and he was discharged with no deficit. A 67-year-old man underwent CEA for the symptomatic side. The patient developed no postoperative neurologic deficits except for hoarseness. Four weeks later, CAS was performed for the contralateral asymptomatic side. After the procedure, however, severe hypotension occurred, and treatment by continuous injection of catecholamine was necessary to maintain systematic blood pressure. The patient was ultimately discharged with no deficit. The combined therapy of CAS for the asymptomatic side and then CEA for the symptomatic side has been recommended by several authors. However, one of the problems of this strategy is the higher incidence of postprocedural hemodynamic complications, and hypotension after CAS may be dangerous for the symptomatic hemisphere. We suggest a combined therapy using CEA for the symptomatic side and then CAS for the asymptomatic side can be 1 beneficial treatment option for patients with bilateral carotid stenosis without coronary artery disease.

Superficial or deep cervical plexus block for carotid endarterectomy: a systematic review of complications †

Carotid endarterectomy is commonly conducted under regional (deep, superficial, intermediate, or combined) cervical plexus block, but it is not known if complication rates differ. We conducted a systematic review of published papers to assess the complication rate associated with superficial (or intermediate) and deep (or combined deep plus superficial/intermediate). The null hypothesis was that complication rates were equal. Complications of interest were: (1) serious complications related to the placement of block, (2) incidence of conversion to general anaesthesia, and (3) serious systemic complications of the surgical-anaesthetic process. We retrieved 69 papers describing a total of 7558 deep/combined blocks and 2533 superficial/intermediate blocks. Deep/combined block was associated with a higher serious complication rate related to the injecting needle when compared with the superficial/intermediate block (odds ratio 2.13, P = 0.006). The conversion rate to general anaesthesia was also higher with deep/combined block (odds ratio 5.15, P < 0.0001), but there was an equivalent incidence of other systemic serious complications (odds ratio 1.13, P = 0.273; NS). We conclude that superficial/intermediate block is safer than any method that employs a deep injection. The higher rate of conversion to general anaesthesia with the deep/combined block may have been influenced by the higher incidence of direct complications, but may also suggest that the superficial/combined block provides better analgesia during surgery.

Blood pressure in the artery distal to an intraarterial embolus during thrombolytic therapy for occlusion of a major artery: a predictor of cerebral infarction following good recanalization

Object. The aim in this study was the investigation of back pressure in arteries distal to the occlusion site during intraarterial thrombolysis as well as the usefulness of back pressure measurement in combination with diffusion-weighted (DW) magnetic resonance (MR) imaging to predict the occurrence of ischemic lesions following good recanalization.

Methods. Twenty-five consecutive patients with severe hemiparesis caused by embolism of the internal carotid artery (10 patients) and the proximal middle cerebral artery (15 patients) were treated using intraarterial thrombolysis. Systolic back pressure, measured through a microcatheter in the artery just distal to the emboli, ranged from 22 to 78 mm Hg. According to an angiographic inclusion criterion for good recanalization—that is, recanalization of the M2 or more distal arteries at the end of thrombolysis—21 of 25 patients underwent evaluation in this study. In 14 patients volumes of low-density areas on computerized tomography (CT) scans obtained 2 months postthrombolysis were smaller in comparison with volumes of hyperintense areas on DW MR images acquired before treatment, whereas these low-density areas were larger in seven patients. Compared with those on initial DW MR images, the volume of abnormalities on CT scans obtained 2 months posttreatment were significantly reduced in patients with a systolic back pressure greater than 30 mm Hg (16 patients) than in those with a back pressure of 30 mm Hg or less (five patients) (p < 0.05). Systolic back pressures greater than 30 mm Hg were associated with significantly better modified Rankin Scale scores than those 30 mm Hg or less (p < 0.05).

Conclusions. Back pressure measurement in combination with DW MR imaging can be used to predict the occurrence of infarction as demonstrated on CT scans following thrombolysis.

The value and limitations of magnetic resonance angiography of the circle of Willis in patients undergoing carotid endarterectomy

Magnetic resonance angiography is a useful technique to determine the patency of the circle of Willis when compared with conventional four-vessel angiography. The purpose of this study is to determine whether the integrity of the circle of Willis, assessed by magnetic resonance angiography, provides adequate collateral cerebral circulation during carotid endarterectomy and correlates with internal carotid artery back pressure. Over a recent 20-month period, 35 patients were studied preoperatively with magnetic resonance angiography of the carotid bifurcations of the circle of Willis and the vertebrobasilar system. All patients underwent standard carotid endarterectomy with intraoperative measurement of internal carotid artery back pressure. Patients with an internal carotid artery back pressure < 50 mmHg had an intraluminal shunt placed. Deficiencies in branches of the circle of Willis, the carotid bifurcation and the vertebrobasilar system determined by magnetic resonance angiography were correlated with internal carotid artery back pressure using Fisher's exact test. Only one patient had a completely intact circle of Willis. Eleven of 16 patients (69%) who had an internal carotid artery back pressure < 50 mmHg had an occluded A1 segment of the anterior cerebral artery combined with an occluded posterior communicating artery, whereas only five of 19 patients (26%) who had an internal carotid artery back pressure > 50 mmHg had similar findings (P < 0.03). Severity of occlusive disease of the contralateral internal carotid artery and the basilar artery did not independently predict internal carotid artery back pressure. An occluded anterior branch of the circle of Willis in combination with an occluded posterior branch of the circle of Willis is associated with an internal carotid artery back pressure < 50 mmHg. Although magnetic resonance angiography of the circle of Willis may provide valuable anatomic information, it is not sufficiently accurate to predict the need for carotid shunting and therefore its use cannot be justified on a routine basis.

Carotid endarterectomy. Lessons from intraoperative monitoring--a decade of experience

OBJECTIVE

The authors analyzed a single institution's 10-year experience with intraoperative monitoring during 709 primary carotid endarterectomies and investigated the impact of contralateral internal carotid artery stenosis on carotid artery stump pressure (SP).

SUMMARY BACKGROUND DATA

Stump pressure reflects the combination of contralateral carotid artery anatomy, collateral intracranial vasculature, and systemic blood pressure. By controlling for blood pressure with a stump index (SI) (SI = [SP/mean arterial pressure] x 100), a correlation between pressure and contralateral carotid artery anatomy can be demonstrated. Although the use of SP has long been advocated as an indicator of adequate cerebral perfusion, its correlation with perioperative complications while using an intraluminal shunt has not been evaluated completely.

METHODS

From a series of 886 primary carotid endarterectomy cases, SP and mean arterial pressure were measured prospectively in 709 procedures. Temporary intraluminal shunts were used in cases with demonstrated contralateral carotid occlusion, prior cerebrovascular accident (CVA), or SPs less than 35 mmHg. Ipsilateral and contralateral angiographic degree of carotid stenosis was recorded at the time of the operation. Neurologic status was recorded prospectively for all 709 procedures. Operative electroencephalogram (EEG) changes and SP then were compared with the neurologic status of the patient in the perioperative period.

RESULTS

The mean SP for the group (n = 709) was 46.7 +/- 15.3 mmHg (mean +/- standard deviation [SD]) with a mean SI of 54.9 +/- 22.6. The distribution for the SI is a more gaussian curve than that for SP. There were 19 ipsilateral CVAs (2.7%). The mean SP in the nonstroke group was 47.1 +/- 15.2 mmHg (mean SI = 54.7 +/- 16.5) compared with 31.9 +/- 13.2 mmHg (mean SI = 38.8 +/- 18.2) in the stroke group (P < 0.0001). Stroke rate for SP < or = 35 mmHg was 7% (13/185) versus 1.1% (6/524) for SP > 35 (p < 0.0001). Stump index and SP are related to contralateral carotid artery stenosis. The pattern of SI or SP versus contralateral stenosis is biphasic, with an increase at 75%. If SI is < or = 40, the mean contralateral stenosis is 55.1%; if SI is > 40, the mean contralateral stenosis is 35.1% (p < 0.05). Continuous EEG monitoring was completed for the 549 most recent operations. Patients who had a perioperative stroke had EEG changes observed during the procedure in only 6 of 12 cases (50% sensitivity), with 76% specificity. Using SP < or = 35 mmHg, sensitivity was 68% and specificity was 75%.

Local anesthesia in carotid angioplasty

PURPOSE

To determine the safety and efficacy of local anesthesia for percutaneous carotid angioplasty and stenting performed via a direct common carotid access.

METHODS

Deep cervical plexus blockade was used for anesthesia in 22 of 32 patients (26 males; mean age 66 years) undergoing percutaneous carotid balloon angioplasty and/or stenting via direct carotid puncture. Local anesthesia was selected according to patient preference (n = 9); advanced age (n = 4); ischemic heart disease (n = 4); intended extracorporeal circulation for unstable angina (n = 3); and an incompetent circle of Willis (n = 2). The technique involved injection of bupivacaine hydrochloride along the C2, C3, and C4 transverse processes. No superficial cervical plexus blockade was used.

RESULTS

No complications of anesthesia were observed, though there were cases in which surgery became necessary under local anesthesia for angioplasty-related complications. These conversions were accomplished without difficulty.

CONCLUSIONS

Cervical nerve blockade appears to be a safe and effective anesthetic method for endovascular carotid interventions performed percutaneously through direct carotid puncture.

Stump pressure, electroencephalographic changes, and the contralateral carotid artery: another look at selective shunting

BACKGROUND

Selective shunting during carotid endarterectomy is associated with the lowest operative stroke rate; therefore, patient selection for carotid shunting is critical. Electroencephalography (EEG) can detect ischemic brain cell dysfunction before irreversible injury. The carotid stump back pressure (CSP) has been inconsistent in determining the need for shunting, and contralateral carotid disease has had a variable impact. The purpose of this study was to evaluate CSP and operative EEG changes, and to determine the effect of contralateral carotid artery disease on determining the need for carotid shunting.

METHODS

In 140 consecutive carotid procedures, operative EEG and CSP were monitored, and contralateral carotid disease was documented. The carotid stump pressure/mean arterial pressure index (CSP/MAP) was also calculated to determine if this was a better indicator of the need for shunting than the CSP alone.

RESULTS

There was a 58% incidence of EEG changes when the CSP was < or = 25 mm Hg, 32% with a CSP of 26 to 50 mm Hg, and 4% with a CSP > 50 mm Hg. There was a 43% incidence of EEG changes and lower CSP among patients with a contralateral occlusion, both of which were significantly different from patients with a patent contralateral carotid artery. Three patients with CSP > 50 mm Hg had EEG changes, but none had a contralateral occlusion. Two patients had permanent neurologic deficits, and 2 had transient deficits. Excluding combined procedures, operative stroke rate was 0.8%.

CONCLUSIONS

A CSP of < 50 mm Hg achieved a sensitivity of 89% in patients who developed ischemic EEG changes during carotid clamping, and a pressure > 50 mm Hg had a negative predictive value of 96%. However, a CSP of < 50 mm Hg had a positive predictive value of only 36%. Neither the addition of the status of the contralateral carotid artery or the calculation of the CSP/MAP improved the sensitivity of the CSP in determining the need for shunting. Operative EEG monitoring remains the most sensitive guide to carotid shunting in patients undergoing carotid endarterectomy under general anesthesia.