Carotid endarterectomy without a shunt. Experiences using hyperbaric general anesthesia

Reconstructive surgery of the extracranial arteries

The first carotid endarterectomy (CEA) is usually accredited to Eastcott who reported in 1954 the successful incision of a diseased carotid bulb with end-to-end anastomosis of the internal carotid artery (ICA) to the common carotid artery (CCA). During the following years surgeons were quick to adopt and improve the intuitively attractive procedure. But by the early to mid 1980s several leading neurologists began to question the growing number of CEAs performed at that time. Six major CEA trials were then designed which are now completed or nearing completion. Most conclusive data are available from the North American Symptomatic Carotid Endarterectomy Trial (NASCET) for symptomatic carotid disease, and from the Asymptomatic Carotid Atherosclerosis Study (ACAS) for asymptomatic carotid disease. The key result of these studies is that CEA is beneficial to high grade symptomatic and asymptomatic carotid stenosis. While the benefit in symptomatic disease is clear, it may be negligible in asymptomatic patients suffering from other medical conditions, the most important being coronary artery disease. Since the conclusions from the different studies vary significantly, guidelines and recommendations with regard to CEA have been issued by a number of interest groups, so-called consensus conferences. The best known guidelines are published by the American Heart Association (AHA). However, the practice of interest groups to issue guidelines is currently being criticized, the main reason being that interest groups have different ideas and all claim the right to issue guidelines. At present we recommend CEA for symptomatic high-grade stenosis in patients without significant coincident disease. With regard to asymptomatic stenosis we suggest surgery to otherwise healthy patients if the stenosis is very narrow or progressive. Preoperative evaluation has changed over the years. Currently we recommend duplex sonography in combination with intra- and extracranial magnetic resonance angiography (MRA). Concurrent coronary artery disease is a major consideration in the perioperative management, and the use of a specific algorithm is recommended. Surgery is performed under general anaesthesia with intraoperative monitoring such as electroencephalography (EEG) and transcranial Doppler (TCD). A temporary intraluminal shunt is used selectively if after cross-clamping the flow velocity in the middle cerebral artery (MCA) falls to below 30 to 40% of baseline. For years we employed routine barbiturate neuroprotection during cross-clamping. At the present time we use barbiturate selectively, if the flow velocity in the MCA falls to below 30 to 40% of baseline and if the use of a temporary intraluminal shunt is not possible due to difficult anatomic conditions. The reason to abandon systematic barbiturate protection was to accelerate recovery from anaesthesia. Our patients are monitored overnight on the ICU or a surveillance unit. Routine hospitalization after surgery is 5 to 7 days with a control duplex sonography being performed prior to discharge. A number of details with regard to surgical technique and perioperative management are a matter of discussion. Our surgical routine is described here step by step. Such management resulted in 6 major complications among the 402 cases with 4 of cardiopulmonary and 2 of cerebrovascular origin. For the future we can expect the development of percutaneous transluminal techniques competing with standard carotid endarterectomy. At the present time several comparative studies are under way. Irrespective of the technical approach to treat carotid stenosis, several other issues have to be clarified before long. One of the major unresolved items is the timing of treatment after completed stroke. In this regard prospective trials need to be performed. Although numerically not as important as carotid stenosis, vertebral artery (VA) and subclavian artery (SA) stenoses are more and more accepted as indication for surgical

Comparative results of staged and simultaneous bilateral carotid endarterectomy: a clinical study and surgical treatment

OBJECTIVE

Bilateral carotid stenoses are actually managed by staged endarterectomy. The present study compares the results of the above surgical procedure with simultaneous bilateral carotid endarterectomy.

METHODS

Sixty-four carotid endarterectomies were carried out on two groups of thirty-two patients with bilateral carotid stenoses. Fifteen patients (group A) were subjected to staged and 17 patients (group B) who were subjected to simultaneous bilateral carotid endarterectomies.

RESULTS

The mortality rate was zero in both groups; no statistically significant difference was found concerning complications related to the heart, neurological deficit and postoperative hypertension.

CONCLUSIONS

Simultaneous carotid endarterectomy is a challenging and technically demanding operation but with limited indications in strictly selected patients. The development of methods of more effective monitoring and protection of the cerebral cells might broaden the indications of such a surgical tactic in the future. Staged carotid endarterectomy, however, remains the method of choice for the management of bilateral carotid occlusive disease.

Carotid endarterectomy without a shunt for symptomatic lesions associated with contralateral severe stenosis or occlusion

PURPOSE

The purpose of this study was to assess the adequacy of thiopental protection against ischemic cerebral damage in patients undergoing carotid endarterectomy for symptomatic stenosis greater than 70% in association with contralateral stenosis greater than 70% or contralateral occlusion.

METHODS

All patients (n=259) with severe bilateral carotid disease who underwent carotid endarterectomy for symptomatic stenosis greater than 70% were extracted from the database of an ongoing prospective carotid surgery study. Large-dose thiopental sodium without shunting was used for cerebral protection during endarterectomy. Asymmetric electroencephalogram changes during the operation, carotid occlusion time, stroke onset, and neuropathologic outcomes were analyzed.

RESULTS

Three contralateral strokes occurred in the series, producing a cerebral morbidity/mortality rate of 1.2% (major 0.4%, minor 0.8%). Transient morbidity was 1.9% made of two reversible ischemic neurologic deficits and three transient ischemic attacks. New asymmetric electroencephalography changes were seen in 49 (19% patients, one of whom had transient deficit. Average occlusion time was 35 minutes. All strokes occurred within 24 hours of the procedure. Patients with previous stroke and and systemic hypertension seemed at greatest risk, and the contralateral hemisphere was the area at greatest risk. All transient deficits were ipsilateral and related to technical complications rather failed protection.

CONCLUSIONS

Thiopental cerebral protection eliminates strokes caused by complications of shunting, prevents ischemic stroke during carotid occlusion for periods up to 67 minutes (average 35 minutes), allows meticulous management of the operative site, may modify or minimize clinical neurologic deficit, and in our experience has rendered intraluminal shunting obsolete.

Carotid stump pressure, stump pulse, and retrograde flow

In order to obtain a more comprehensive intraoperative hemodynamic profile and to predict hypoperfusion during carotid endarterectomy, stump pressure, stump pulse, and retrograde internal carotid flow were measured in 261 patients. Our results show a significant correlation between stump pressure and retrograde flow (p < 0.001), stump pressure and the presence of a stump pulse (p < 0.001), and retrograde flow and the presence of a stump pulse (p < 0.001). We also demonstrated a significant correlation between stump pressure (lower), retrograde flow (less), and the absence of a stump pulse in patients with contralateral carotid artery occlusion. There was no correlation between the indication for carotid endarterectomy and any hemodynamic measurement. The triad of stump pulse, stump pressure, and retrograde flow accurately reflects collateral blood flow when the carotid is cross-clamped. These determinations can be obtained at low cost and are easily and rapidly performed. A protocol for selective shunting in patients undergoing carotid endarterectomy with general anesthesia is suggested.

Carotid endarterectomy for asymptomatic patients. Assessing results of a quantitative synthesis

Carotid endarterectomy (CE) surgery for asymptomatic patients remains controversial despite hundreds of published studies and recent randomized trials. Safety and efficacy are assessed using a quantitative synthesis method derived from meta-analysis and a "critical multiplist" inference approach. In addition, multivariate analyses reveal that use of a surgical shunt could further improve CE outcomes. Methods are examined for both their "confirmatory" and "exploratory" value.

Perioperative stroke. Part I: General surgery, carotid artery disease, and carotid endarterectomy

Although stroke, defined as a focal neurological deficit lasting more than 24 hr, is uncommon in the perioperative period, its associated mortality and long-term disability are high. No large-scale data are available to identify the importance of recognized risk factors for stroke in the perioperative period. A review of the literature shows that the incidence and mechanism of its occurrence are influenced by the presence of cardiovascular disease and the type of surgery. The most common cause of perioperative stroke is embolism. In non-cardiac surgery, the incidence of perioperative stroke is higher among the elderly. Properly administered, controlled hypotension is associated with minimal risk of stroke. Cerebral vasospasm may be the cause of focal cerebral ischaemia in eclamptic patients, and the aggressive treatment of hypertension may exacerbate the neurological damage. The risk of stroke associated with carotid endarterectomy is closely related to the preoperative neurological presentation, and the experience of the surgical/anaesthetic team. Symptomatic cerebrovascular disease, acute stroke, asymptomatic carotid lesions, preoperative assessment of risk, local and general anaesthesia, cerebral protection and monitoring during carotid endarterectomy are discussed with reference to reducing the risk of perioperative stroke. Adequate monitoring and protection have minimized the risk of ischaemia from carotid clamping, and the major mechanism of stroke is embolization.

Declining morbidity and mortality of carotid endarterectomy. The Wake Forest University Medical Center experience

The 30-day mortality as well as morbidity for stroke and myocardial infarction were determined by review of the charts for every carotid endarterectomy (N = 389 operations on 356 patients) performed at Wake Forest University Medical Center from 1979 through 1983 to ascertain whether the 16% morbidity and 6% mortality documented in our previous report of 1978 had changed over time. For endarterectomies performed on asymptomatic patients (n = 155), major morbidity included 2 myocardial infarctions and 1 stroke (1.9%). There were 3 fatalities--2 myocardial infarctions and 1 stroke (1.9%). For the symptomatic group (n = 234), major morbidity was 2.1%, mortality 2.6%. The combined morbidity for asymptomatic and symptomatic carotid stenosis was 2%, mortality 2.3%. Perioperative stroke rate (morbidity plus mortality) was 2.6%, 9 ipsilateral to the carotid endarterectomy, suggesting distal embolism as its probable cause. We contend that quality control measures implemented to correct the unacceptable rates reported in 1978 have contributed to dramatic and sustained reductions in complication rates.

Carotid endarterectomy for cerebrovascular insufficiency: long-term results in 592 patients followed up to thirteen years

Seven hundred forty-eight carotid endarterectomies were performed on 592 patients with cerebrovascular insufficiency during a 13-year period. Overall operative procedure mortality was 2.7%. In the last 6 years, using a shunt routinely and avoiding operation on acute strokes, mortality was 1.47%. In frank strokes it was 3.7%; in transient ischemia, 0.77%; and zero for chronic ischemia and asymptomatic bruits. Incidence of operation-related deficits among transient ischemia and asymptomatic bruit patients was 0.9% for transient weakness and 2% for permanent deficits. Of 172 long-term deaths, 23 were due to cerebral causes, or 3.9% of the entire series. Among frank stroke survivors, 30.2% are normal and 58.7% improved. In transient ischemia survivors 81% are normal and 15.7% improved. In 65 asymptomatic bruit patients operated upon electively, two had strokes during follow-up, one mild and one severe. Among 37 asymptomatic bruit control patients, 24 or 65% developed symptoms of transient ischemia or frank strokes. Of 118 totally occluded carotid arteries explored, flow was restored in 48 (40.7%) but could not be restored in 70 (59.3%). For cerebral protection during carotid endarterectomy the routine use of a temporary inlying bypass shunt with general anesthesia is advocated for all partial occlusions. Endarterectomy is most useful for transient ischemia and selected patients with mild frank strokes and asymptomatic bruits. Acute profound and rapidly progressing strokes should not be operated upon as an emergency, but allowed to stabilize for several weeks and then be considered for possible operation.

Life expectancy and late stroke following carotid endarterectomy

A review of the UCSD experience with 456 consecutive carotid endarterectomy procedures confirms the acceptably low operative mortality and morbidity associated with this operation. Immediate complications were not different when routine or selective shunting was performed, but the patients with a low internal carotid artery back pressure had higher operative complication rates. The coexistence of atherosclerosis in other parts of the body severe-enough to warrant surgery for them was not associated with either higher early or late carotid surgery complication rates. Following both coronary bypass and carotid procedures, the late mortality was decreased, and the late incidence of stroke was particularly low in comparison to the remainder of the patient group. Late follow-up emphasized the high continuing attrition rate from all causes in these patients. Late strokes continued to occur, particularly in patients with prior strokes and severe preoperative bilateral carotid disease. The late course of patients with posterior circulation transient ischemic attacks treated by carotid endarterectomy was quite similar to that of patients treated for anterior circulation transient ischemia attacks (TIAs). Newer postoperative screening procedures may decrease the incidence of late postoperative stroke by identifying recurrent carotid stenosis while it is still in the asymptomatic stage.

Carotid endarterectomy under regional (conductive) anesthesia

Carotid endarterectomy is reliable in the prevention of strokes due to arteriosclerotic disease at the carotid bifurcation. This is a retrospective review of 314 carotid endarterectomies performed at the University Health Center of Pittsburgh. The objectives of the study were to determine if regional anesthesia was a safe technique for carotid endarterectomy and to determine whether the neurologic complications that occurred were embolic or ischemic in origin. In patients who were neurologically intact before operation, the perioperative mortality was 0.88% and the incidence of neurologic complications was 3.1%. This is comparable to the current literature. Observations of the awake patient suggested that half the neurologic deficits that occurred in this series were due to embolization rather than to cerebral ischemia. Further more, the incidence of non-neurologic complications under general anesthesia was 12.9%. Under regional anesthesia, the incidence of non-neurologic complications was 2.8%. The data supports carotid endarterectomy under regional block as safe and reliable method.

The current status of carotid artery surgery

The natural history of extracranial cerebrovascular disease and available alternatives in its treatment are reviewed. An evaluation of the evidence suggests that carotid endarterectomy is the treatment of choice in patients with transient ischemic deficits, provided that an anatomically appropriate lesion can be identified. These patients have a 25-38% chance of stroke if untreated, which can be reduced to 5-10% by carotid endarterectomy. Patients with asymptomatic carotid stenosis who are good operative risks are also candidates for surgery, although this issue remains controversial. Patients with small asymptomatic ulcerated carotid plaques have a relatively benign prognosis and should not undergo preventive carotid surgery. Carotid surgery is occasionally indicated in patients with vertebral basilar insufficiency and carotid stenoses, fibromuscular dysplasia, or carotid kinks associated with symptoms of ischemia. Carotid endarterectomy may be performed with an overall mortality of 1-2% and morbidity of 2-5% if the patients are carefully selected and the surgical team is expert.

David M. Hume Memorial Lecture. An overview of the stroke problem in the carotid territory

In a review of 1,000 carotid endarterectomies performed over a 20 year period, there was relief of transient ischemic attacks in approximately 85% of patients, an operative mortality of 1.3%, due almost exclusively to myocardial infarction, and a recurrent stenosis rate of 3.1%. Coexisting cardiac disease constitutes the greatest operative hazard. Continuous electroencephalographic monitoring is a reliable method of detecting inadequate cerebral perfusion during carotid cross clamping and for the selective use of a temporary inlying carotid shunt. An atherosclerotic plaque in the carotid system constitutes a greater risk than elsewhere in the peripheral arterial system and should not be considered an innocent lesion. Prophylactic carotid endarterectomy can be performed with almost no mortality and morbidity. Antiplatelet agents, while useful in reducing the incidence of transient ischemic attacks, do not seem to provide equal protection against stroke and death from stroke.

An expedient shunt for the small internal carotid artery

A simple and readily available device was used as a shunt during carotid endarterectomy in four cases in which difficulty in inserting a conventional shunt into the internal carotid artery was encountered. It was also used preferentially in one case of external carotid endarterectomy. No apparent injuries occurred in conjunction with its use, and in none of the four patients did neurologic complications develop. For those who wish to use a shunt in all cases of carotid endarterectomy, this device provides an expedient means of shunting in cases in which difficulty in inserting a conventional shunt is encountered.

Carotid endarterectomy without temporary intraluminal shunt. Study of 309 consecutive operations

A prospective study was undertaken to determine the efficacy of performing carotid endarterectomy without an intraluminal shunt. During a two-year period, 240 patients, ranging in age from 36 to 89 years, underwent 309 consecutive carotid endarterectomies. The indication for operation was transient ischemic attacks in 151 (63%) patients, asymptomatic carotid bruit in 67 (28%), and previous stroke in 22 (9%). Internal shunts were not used in any patients and all arteriotomies were patched with a preclotted knitted Dacron velor patch. Systemic heparinization was used during the procedure. The early postoperative mortality was 0.64% (2/309). Both deaths were caused by myocardial infarction. The incidence of stroke after operation was 1.29% (4/309). Neither carotid clamp time nor the presence of contralateral disease correlated with the occurrence of postoperative stroke. According to results of angiography, 22 patients had total occlusion of the contralateral internal carotid artery with satisfactory intracranial circulation. No postoperative strokes occurred in this subgroup. Results of this study revealed that equally good or superior results may be obtained without a temporary shunt in performing carotid endarterectomy.

Surgical experience with simultaneous bilateral carotid endarterectomies

Eighty patients who had undergone bilateral carotid endarterectomy at the same operation were reviewed. All operative procedures were performed under general anaesthesia and during systemic heparinization and in all but six cases by using internal shunt. There were three deaths related to the operation representing 3.8% hospital mortality. Transient neurological deficits were noted in four patients (5% incidence) and permanent neurological deficits in four patients (also 5% incidence). A 100% late follow-up after an average period of 48 months revealed that 85.7% of the long-term survivors were functionally normal or improved. There were ten late deaths with heart disease accounting for 50% and stroke 30%.

Stroke associated with carotid endarterectomy

Between 1966 and 1976, eleven strokes occurred in association with 509 carotid endarterectomies performed at Walter Reed Army Medical Center. Contralateral carotid arterial occlusion with unilateral stenosis, bilateral carotid stenoses, or multiple extracranial (with or without intracranial) stenoses were present in all patients in whom stroke developed. Preventable technical factors contributing to or directly causing stroke were identifiable in six of the eleven patients. Better appreciation of the high risks associated with the above arteriographic patterns and elimination of technical mishaps should lead to an improvement in our already respectably low stroke rate of 2.2 per cent.

EEG surveillance as a means of extending operability in high risk carotid endarterectomy

Some patients who have transient ischemic attacks are denied operation because severe occlusive lesions in other extra-cranial arteries may be inappropriately interpreted as constituting an unacceptable surgical risk, or because the lesion is so distal as to make its removal hazardous. Failure of endarterectomy is usually due to incomplete removal of the lesion or to thrombosis upon the frayed intima. Such lesions require excellent visualization and meticulous surgical technique -- not always possible with a shunt. Among 130 consecutive carotid endarterectomies performed under general anesthesia, EEG changes consistent with cerebral ischemia appeared in only nine (7%). These patients required a shunt. In 11 patients normal EEG tracings were obtained during endarterectomy despite contralateral carotid occlusion. None of these patients had a neurological deficit. Continuous EEG monitoring is a reliable method of detecting changes in cerebral perfusion, permits a more meticulous endarterectomy in high-lying lesions without a shunt, and extends operability in high risk patients. Angiographical findings may be an unreliable predictor concerning risk of endarterectomy.

Carotid endarterectomy

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Carotid endarterectomy: Is a shunt necessary?

Seventy-seven carotid endarterectomies performed on fifty-nine patients, using induced systemic hypertension during carotid artery clamping, were reviewed. The risk of cerebral ischemia is reduced to a minimum by this technic. The measurement of the internal carotid artery stump pressure is an excellent guideline for the need of additional brain protection. An internal shunt is rarely necessary. Thromboembolic phenomena contributed to the major neurologic complications encountered (two deaths and one stroke). Extreme gentleness and careful surgical technic cannot be overemphasized.

Carotid endarterectomy

During the last 20 years carotid endarterectomy has become an important method of treatment for selected patients with arteriosclerotic cerebrovascular disease. Improvement in selection of patients for operation, in anesthetic management, and in surgical techniques has resulted in a decline in complications associated with the operation. The steps of the operation are described in detail. The causes, prevention, and treatment of the surgical complications are discussed.

Surgical aspects of carotid-vertebral insufficiency

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Carotid endarterectomy for cerebrovascular insufficiency: long-term results in 592 patients followed up to thirteen years

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