Carotid bruit: a follow-up report on its significance in patients undergoing an abdominal aortic operation

Stroke in the postoperative period

Stroke in the postoperative period requires a certain level of sophistication in dealing not only with the patient, but also with the family and significant others. The consultant who is called in to assess the patient must deal with the delicate matter of addressing a presumably unforeseen complication; this often requires political deftness when the surgeon is reluctant to acknowledge that anything possibly could go awry. It is the ultimate hope of all involved that the patient will have a speedy and full recovery. It is important for the patient to be evaluated properly and thoroughly in an effort to prevent a minor, reversible deficit from becoming a major, irreversible neurologic disability. Family members should have all findings and the implications of such findings thoroughly explained to them. Efforts to minimize the potential ramifications of a postoperative stroke generally are not well received and can lead to questions about the integrity of the surgical team as well as the quality of care.

The haemodynamic effect of internal carotid artery stenosis on cerebral perfusion during aortic surgery

OBJECTIVES

to determine the impact of the extracranial internal carotid stenosis on cerebral perfusion during aortoiliac surgery.

DESIGN

prospective study.

MATERIAL AND METHODS

of 432 consecutive patients undergoing aortoiliac reconstruction, 16/86 (18%) with >70% internal carotid artery stenosis, underwent inverted surgical timing (aortic reconstruction first and carotid endarterectomy second). Preoperative Transcranial Doppler (TCD) with and without acetazolamide was used to evaluate cerebrovascular reserve capacity (CRC). Intraoperatively, middle cerebral artery flow velocity (mean MCAv) and systemic blood pressure (SBP) were recorded.

RESULTS

preoperatively, all 16 patients had good CRC (increase in mean MCAv: 66% right and 72% left). Intraoperatively, the mean MCAv (from 49+/-13 to 45+/-14 cm/s p=0.0249) and SBP decreased (from 127+/-25 to 113+/-22 mmHg p=0.0016). In patients with unilateral carotid disease, declamping had no effect on left mean MCAv despite a significant decrease of SBP (129+/-44 to 113+/-21 mmHg p=0.0211). In those with bilateral disease, declamping decreased both mean MCAv: from (48+/-12 to 39+/-10 cm/s p=0.011) and SBP (123+/-26 to 111+/-25 mmHg p=0.0479). No perioperative neurological deficit occurred.

CONCLUSIONS

if CRC is normal or still effective, aortoiliac reconstruction does not impair cerebral perfusion.

Carotid stenosis and perioperative stroke risk in symptomatic and asymptomatic patients undergoing vascular or coronary surgery

BACKGROUND AND PURPOSE

The management of asymptomatic carotid stenosis found before vascular or coronary surgery is unclear from the literature. We aimed to define the relation of carotid stenosis to perioperative stroke in all patients, symptomatic and asymptomatic, and so determine a policy for the management of asymptomatic carotid stenosis in patients requiring major surgery.

METHODS

We conducted a prospective clinical and Duplex ultrasound study of 358 consecutive noncarotid major vascular or coronary artery bypass operations, with a moratorium on endarterectomy for asymptomatic carotid stenosis.

RESULTS

There were 145 vascular and 213 coronary bypass operations. Ten of the 49 cases with prior symptoms of cerebral ischemia (38 carotid, 11 vertebrobasilar) had symptomatic stenosis of 50% or greater or occlusion, and 3 of these (30%) had ipsilateral perioperative cerebral infarction (95% confidence interval, 6.67% to 65.25%). Two of these occurred ipsilateral to symptomatic carotid occlusions, and 1 occurred ipsilateral to an 80% symptomatic stenosis. One symptomatic patient with bilateral 30% stenosis had a perioperative infarct in the asymptomatic hemisphere. Among the 309 asymptomatic patients, 1 perioperative infarct occurred ipsilateral to carotid stenosis of 30%. In all there were 5 (1.4%) perioperative (within 72 hours) and 2 late (after 18 days) strokes. All strokes were hemisphere infarcts confirmed by computed tomography. There were 53 cases with 50% or greater asymptomatic carotid stenosis or occlusion, including 28 with 80% or greater stenosis or occlusion. None had an ipsilateral perioperative stroke (95% confidence interval, 0% to 6.72%).

CONCLUSIONS

We conclude that the risk of perioperative stroke related to symptomatic carotid stenosis may be high, but for asymptomatic carotid stenosis the risk is low and does not justify preoperative prophylactic carotid endarterectomy.

Advanced carotid disease in patients requiring aortic reconstruction

Perioperative stroke is a devastating complication of abdominal aortic operations. Patients requiring aortic reconstruction with advanced carotid occlusive disease pose a particularly challenging management problem regarding timing of operations. All patients (n = 121) undergoing both carotid artery endarterectomy (CEA) and abdominal aortic reconstruction (AAR) within 1 year of each other between 1979 and 1989 were reviewed. The sequence of operation was analyzed to determine its effect on early and late outcome. CEA was the first operation in 99 patients (group I); AAR was performed first in 22 patients (group II). Age, gender, number, types of risk factors, and associated medical problems were similar in both groups. Indications for CEA were: transient ischemic attacks (TIAs), recent ipsilateral stroke, or high-grade asymptomatic carotid artery stenosis exceeding 80%. Indications for aortic operation included: abdominal aortic aneurysm, aortoiliac occlusive disease, and combined aortic and renovascular disease. There were five perioperative strokes, two in group I (2%) and three in group II (14%) (p < 0.04). All strokes occurred after AAR. There were five perioperative deaths (4%), four in group I (4%) and one in group II (5%). Overall survival was significantly greater in group I compared to group II (p < 0.04); 5-year survival was 77% and 51%, respectively. Multivariate analysis demonstrated age, hypertension, and diabetes to adversely affect survival; CEA as the first procedure, however, had a protective effect. Importantly, eight strokes occurred in group I in late follow-up, but only one was ipsilateral to the CEA. We conclude that CEA in selected patients who require AAR is safe, and, when performed prior to abdominal aortic repair, reduces perioperative stroke and may improve long-term survival.

Anesthetic management of abdominal aortic surgery: a retrospective review of perioperative complications

The incidence of perioperative complications was retrospectively reviewed in 103 patients who underwent replacement of the abdominal aorta from 1981 to 1987. Eighty-nine of the patients had associated systemic diseases, with hypertension being the most frequent (63%). Ischemic heart disease and cerebrovascular disease had an incidence of 12% and 13%, respectively. Combined anesthesia with lumbar epidural and light general anesthesia (group I) was compared with general anesthesia alone (group II). Excluding patients with a ruptured aneurysm, 39 of 97 patients (40%) had associated intraoperative hypertension, which was related to the presence of preexisting hypertension, but not to the anesthetic technique. Postoperative hypertension also occurred in 39 patients, but the incidence was not related to preoperative hypertension. More patients in group I had postoperative hypertension than in group II (P less than 0.05). In group I, 6 of 22 patients who received epidural morphine developed hypertension compared to 23 out of 37 patients not given epidural morphine (P less than 0.01). There were no significant differences in the overall complication rate between the two groups; however, the incidence of liver dysfunction was significantly higher in group II. Deterioration in renal function occurred in 6 patients, but with no difference between groups. There were three perioperative deaths (2.9%), with two of them resulting from cerebrovascular accidents in patients with a history of cerebrovascular disease. The overall morbidity and mortality were independent of the anesthetic technique.

Asymptomatic carotid disease in patients undergoing major cardiovascular operations: can prophylactic endarterectomy be justified?

This article reviews the published experience supporting or refuting the value of prophylactic endarterectomy in patients with asymptomatic carotid disease who are candidates for major cardiovascular operations. Reports of 1,483 patients subjected to staged or concomitant carotid endarterectomy and coronary artery bypass grafting reveal a perioperative stroke rate of 2.9%. Timing of carotid endarterectomy did not influence stroke rate, but staged procedures were associated with a significantly greater incidence of perioperative myocardial infarction and death. Studies of patients undergoing major cardiovascular surgical operations without prophylactic carotid endarterectomy reported a perioperative stroke rate of 2.7%, which is not significantly different from that of patients undergoing prophylactic carotid endarterectomy. However, the author's prospective study of such patients showed a significant incidence of late postoperative neurologic deficits, which are usually transient ischemic attacks. There is no evidence to justify routine prophylactic carotid endarterectomy of asymptomatic carotid disease before major cardiovascular operations. Patients not undergoing endarterectomy, however, should be given careful postoperative follow-up, because transient ischemic attacks may occur that require surgical intervention.

Concomitant cerebral and myocardial revascularization

Patients who present with concomitant coronary artery disease and hemodynamically significant carotid artery occlusive disease represent a subset of individuals at high risk for myocardial infarction and stroke. Whether the combined surgical approach favorably influences the outcome of patients requiring major cardiovascular surgical procedures remains controversial. However, it is clear that coronary artery bypass procedure and carotid endarterectomy are each beneficial to patients who have the appropriate indications for each procedure individually. The coincidence of carotid and coronary occlusive disease varies with the type of diagnostic tests involved. Angiographic data suggest a coincidence in the range of 1 to 6 per cent, while vascular laboratory screening data in some studies have indicated a coincidence as high as 12 to 14 per cent--a range that appears to be higher than one might expect from clinical experience. It is clear from analyzing the patient profile of this subset of patients from large clinical reviews that in general they are older and sicker and have a higher incidence of cardiovascular risk factors representing more extensive atherosclerosis. It is also well documented that the neurologic complication rate for all patients undergoing coronary bypass is in the range of 2 per cent. Therefore, it should not be expected that the operative mortality rate and risk of perioperative stroke in patients undergoing the combined reconstructive procedure can equal those for either procedure alone. These patients represent a separate clinical subset at higher risk for perioperative complications and need to be evaluated individually.

Correlation of hemodynamically significant internal carotid stenosis with pulsed Doppler frequency analysis

Systolic and mean pressure gradients across internal carotid stenoses were measured at the time of carotid endarterectomy in the arteries of 90 patients, all of whom underwent angiography. Eighty-two of these patients also had pulsed Doppler ultrasonic arteriography with real-time spectrum analysis. There were 71 (79%) high grade stenoses of greater than 50% diameter reduction by angiography. Significant systolic pressure gradients (greater than or equal to 10 mmHg) were identified in 41 patients (46%), 38 (46%) of whom underwent ultrasonic evaluation. A pulsed Doppler frequency measured within the stenosis equal to or greater than 6.5 kiloHertz had a sensitivity of 94.7% (36/38) in identifying pressure reducing lesions with a specificity of 47.7% (21/44). Positive predictive value was 61% (36/59). Angiographic criteria (50% diameter reduction) exhibited a sensitivity of 97.6% (40/41), a specificity of 36.7% (18/49) and a positive predictive value of 56.3% (40/71). Negative predictive value was 94.7% for angiography and 91.3% for ultrasonic arteriography. A pulsed Doppler frequency equal to or greater than 6.5 kiloHertz appears to accurately identify lesions that are at risk to reduce distal internal carotid pressure under operative conditions with a sensitivity similar to angiography. This criterion has a positive predictive value and specificity that is slightly superior to angiography and a high negative predictive value. Pulsed Doppler spectrum analysis provides physiologic information relative to blood flow velocity that is complimentary to the anatomic data provided by angiography for assessing the potential for hemodynamic significance of internal carotid stenoses.

Mechanisms of perioperative cerebral infarction

Perioperative cerebral infarction occurs in less than 1% of general surgical procedures; the mechanism is usually unknown. The clinical features of 12 consecutive perioperative strokes were retrospectively reviewed. Although intraoperative hypotension was frequent, onset of deficit occurred postoperatively in 83% and intraoperatively in 17%. Cardiogenic embolism was a common cause of stroke (42%), with atrial fibrillation present in 4 patients (33%) at the time of stroke. The potential roles of hypercoagulability, hypotension and carotid occlusive disease are discussed. Future reports concerning perioperative stroke should consider the multiple mechanisms and temporal relationship of stroke to the operative procedure.