Recurrent stenosis at site of carotid endarterectomy

Vascular anastomosis using controlled phase transitions in poloxamer gels

Vascular anastomosis is the cornerstone of vascular, cardiovascular and transplant surgery. Most anastomoses are performed with sutures, which are technically challenging and can lead to failure from intimal hyperplasia and foreign body reaction. Numerous alternatives to sutures have been proposed, but none has proven superior, particularly in small or atherosclerotic vessels. We have developed a new method of sutureless and atraumatic vascular anastomosis that uses US Food and Drug Administration (FDA)-approved thermoreversible tri-block polymers to temporarily maintain an open lumen for precise approximation with commercially available glues. We performed end-to-end anastomoses five times more rapidly than we performed hand-sewn controls, and vessels that were too small (<1.0 mm) to sew were successfully reconstructed with this sutureless approach. Imaging of reconstructed rat aorta confirmed equivalent patency, flow and burst strength, and histological analysis demonstrated decreased inflammation and fibrosis at up to 2 years after the procedure. This new technology has potential for improving efficiency and outcomes in the surgical treatment of cardiovascular disease.

Surgical treatment of recurrent carotid artery stenosis

Ninety-two surgical procedures were performed in 82 patients for recurrent carotid artery stenosis. The etiology was recurrent atherosclerosis in 45 cases, myointimal hyperplasia in 20, organized thrombus without a significant underlying plaque in 20, and scarring along the proximal arteriotomy site in seven. The operations included a repeat endarterectomy in 66 cases and reconstruction with an interposition graft in 22. All five major neurological complications occurred in symptomatic patients, and included three instances of intraoperative embolization during exposure of the carotid artery. The majority of neurological complications occurred in symptomatic patients who had intraluminal thrombus confirmed at surgery. There were four perioperative deaths, due to cerebral hemorrhage in two patients and myocardial infarction in two. In the patients whose original surgery was performed at the Mayo Clinic, the risk of recurrent carotid artery stenosis was 3.1% with a primary closure compared to 1.6% when a patch graft was used. These results indicate that surgery for recurrent carotid artery stenosis is technically more difficult and carries a significantly higher risk than surgery for primary disease. The difficulty is due to the friable recurrent plaque associated with intraluminal thrombus, which increases the risk of embolization during carotid artery exposure. In the majority of patients with recurrent atherosclerosis, a repeat endarterectomy can be achieved. However, in some patients, there is scarring without a definite plane of cleavage between the recurrent disease and the underlying media, making an endarterectomy difficult. In these cases, excision of the diseased segment and reconstruction with an interposition graft is the best treatment. The findings presented here also suggest that closure of the original arteriotomy with a patch graft decreases the risk of recurrent carotid artery stenosis.

Doppler colour flow imaging after carotid endarterectomy

Sixty-six patients (72 carotid arteries) were examined after carotid endarterectomy (CEA) using Doppler colour flow imaging (DCFI). Examinations were performed 4-18 days (mean: 7 days) after surgery (32 patients, 34 arteries) or between 2 and 100 months (mean: 39 months) after CEA (34 patients, 38 arteries). Minor vessel wall abnormalities were found in 36% in the internal carotid artery (ICA) and in 55% in the common carotid artery (CCA) or bifurcation. One patient had a minor residual ICA stenosis after surgery; two low-grade stenoses and three ICA-occlusions were diagnosed at follow-up. Altered flow patterns occurred most in CCA (90%) and were predominantly located adjacent to the vessel wall and in dilated vascular segments of the CCA. Disturbed haemodynamics in the ICA were less marked (57%) and frequently found in the central vessel lumen or diffusely distributed. We conclude that surgically induced changes of the vessel geometry and residual or recurrent vascular wall abnormalities are often associated with distinct haemodynamic disturbances, which can reliably be detected by DCFI.

Effects of Furegrelate (Upjohn 63557A) on patency and platelet deposition after canine carotid endarterectomy

Platelet deposition upon endarterectomy sites is a likely cause for early postoperative thrombosis, embolism and restenosis. Platelets aggregate by the thromboxane-prostacycline mechanism. Thromboxane synthetase inhibitors which have been safely administered to humans should reduce platelet deposition after surgical therapy and therefore reduce peri-operative mortality and the prevalence of stroke. A randomized prospective controlled trial was designed to determine vessel patency and platelet deposition associated with the use of 3 mg/kg and 30 mg/kg of Furegrelate (Upjohn U63557A) daily in dogs, who were to have carotid endarterectomy. The 46 treated and 46 control dogs had total carotid patency of 96% and 76% respectively (P less than 0.01). Fourteen dogs treated with 30 mg/kg Furegrelate had no occlusions, compared with a 19% prevalence in 13 controls (P less than 0.02). Furegrelate 10 mg/kg significantly lowered platelet aggregation. Platelet deposition was not significantly changed, however. The reason for this disparity was a probable persistence of vessel wall factors which promoted platelet deposition. This approach might therefore lower rates of peri-operative thrombosis but it would be very unlikely to alter the incidence of restenosis or embolism. Further research could be directed towards modifying the stimuli for platelet deposition upon the endarterectomy site.

Does carotid restenosis predict an increased risk of late symptoms, stroke, or death?

The identification of carotid restenosis as an unexpected late complication of carotid endarterectomy has prompted concerns regarding its importance as a source of new cerebral symptoms, stroke, and death. To investigate these concerns, we analyzed a consecutive series of 507 patients undergoing 566 carotid endarterectomies, each documented as technically satisfactory. Post-operative duplex Doppler examination data at 3 days, 1, 3, 6, 12 months, and annually thereafter in 484 arteries (85.5%) permitted classification of these arteries according to the most severe degree of postoperative stenosis: normal (n = 306); 1% to 19% (n = 89); 20% to 50% (n = 40); more than 50% (n = 49, including 8 occluded). The incidence of more than 50% restenosis was 14.5% in female and 7.7% in male patients (p = 0.003). Life table analyses to 10 years revealed a significantly greater life expectancy among those with restenosis (p = 0.05). Stroke was also less likely in patients with restenosis, although this difference did not reach statistical significance. When survival and stroke were both endpoints, the likelihood of patients with more than 50% restenosis remaining alive and stroke free was also greater than the less than 20% stenotic group (p = 0.03). Thus patients with carotid restenosis were less likely than patients with normal postoperative scans to have late symptoms, stroke, or early death.

Basic fibroblast growth factor stimulates endothelial regrowth and proliferation in denuded arteries

A large percentage of vascular reconstructions, endarterectomies, and angioplasties fail postoperatively due to thrombosis and restenosis. Many of these failures are thought to result from an inability of the vascular endothelium to adequately regenerate and cover the denuded area. After balloon catheter denudation of the rat carotid artery, regrowth of endothelium ceases after approximately 6 wk, leaving a large area devoid of endothelium. Here we show that this cessation of reendothelialization can be overcome by the systemic administration of basic fibroblast growth factor (bFGF). Administration of 120 micrograms bFGF over an 8-h period caused a highly significant increase in the replication rate of endothelial cells at the leading edge of 38.5 vs. 2.1% in controls, and, when given over a longer period of time (12 micrograms daily for 12 d), resulted in a significant increase in the extent of endothelial outgrowth onto the denuded surface. Furthermore, total regrowth could be achieved within 10 wk after balloon catheter denudation when 12 micrograms bFGF was injected twice per week for a period of 8 wk. Endothelium in unmanipulated arteries responded to bFGF with a significant increase in replication, but no increase in endothelial cell density was observed in these arteries. These data demonstrate that bFGF can act as a potent mitogen for vascular endothelial cells in vivo, and add considerably to our understanding of the mechanism underlying endothelial repair after in vivo vascular injuries.

Carotid eversion endarterectomy revisited

Carotid eversion endarterectomy appears to be a safe and anatomically acceptable alternative to the standard carotid bifurcation endarterectomy, as evidenced by the absence of permanent neurologic morbidity and mortality in 98 operations. Preliminary clinical, angiographic, and noninvasive laboratory parameters suggest that there is a significant reduction of both residual technical defects and early recurrent stenosis. Specifically, no perioperative thrombosis or early restenosis was encountered in the 98 endarterectomies. Furthermore, only two technical defects have been noted, and one of these occurred in one patient who required a longitudinal arteriotomy and attendant suture line when the common carotid artery was transected too proximally and the eversion maneuver could not be accomplished. Serial long-term clinical and noninvasive laboratory follow-up evaluation, in addition to indicated postoperative angiography, will continue in an effort to assess the durability of a technical approach to carotid endarterectomy that may minimize residual defects and early restenosis.

Reoperative carotid surgery

Fourteen patients underwent carotid reoperation for symptomatic recurrent carotid stenosis after previous ipsilateral carotid endarterectomy. Eight of these patients presented with focal transient ischemic attacks, two with strokes, and four with vertebrobasilar insufficiency. Recurrent symptoms in eight patients were similar to those prompting the initial carotid endarterectomy. Symptoms recurred early after previous carotid endarterectomy in 2 patients and late in 12 patients. Eleven patients underwent repeat endarterectomy and carotid patch angioplasty, two patients underwent patch angioplasty alone, and one patient underwent carotid artery replacement with a vein graft. Persistent or recurrent focal symptoms referable to the reoperated carotid artery were not present during follow-up (mean 27.4 months, range 4 to 79 months). Vertebrobasilar symptoms were relieved by carotid reoperation in each patient. Although the natural history of asymptomatic postoperative carotid restenosis is unknown, reluctance to reoperate on symptomatic patients is unwarranted, since carotid reoperation can be performed safely with the expectation that recurrent focal and nonfocal vertebrobasilar symptoms will be relieved.

Is duplex follow-up cost-effective in the first year after carotid endarterectomy?

Recent reports have suggested that duplex scanning is an ideal method to noninvasively assess the incidence of recurrent carotid stenosis. However, the timing and frequency of the follow-up studies are controversial. In the present study, 150 patients underwent 173 carotid endarterectomy procedures over a 2 year period. In the postoperative period, a total of 210 duplex studies were carried out on 117 carotid arteries. 21.4 percent of the 117 arteries studied had recurrent stenosis of 16 percent or greater at a mean postoperative follow-up of 15.2 +/- 3 months. Recurrent stenoses were detected early after operation; 96 percent were detected at or before 15 months postoperatively. Patients with recurrent stenoses remained stable and had infrequent symptoms. Several risk factors placed the patient at increased risk for recurrent carotid stenosis: presence of contralateral disease (defined as stenosis of 50 percent or greater), use of tacking sutures, and continued smoking in the postoperative period. Although it remains important for researchers to thoroughly investigate the natural history of atherosclerosis of the extracranial carotid artery, including those changes that occur after carotid endarterectomy, our results indicate that frequent duplex scanning in the first postoperative year is unnecessary and is not cost-effective. Duplex follow-up studies 1 and 12 months after carotid endarterectomy are sufficient for assessing the problem of recurrent stenosis in the first postoperative year.

Prospective assessment of carotid endarterectomy by clinical and ultrasonic methods

Sixty-three carotid endarterectomies in 60 patients were followed by clinical and duplex scanning at 2 weeks postoperatively and at 3-monthly intervals for 3 years (mean 18 months). Four patients died (two of stroke, two of myocardial infarction) and four survivors had recurrent ipsilateral symptoms. Two had an immediate mild hemiparesis which recovered completely within 36 h; in both, the endarterectomized arteries were patent on scanning. The other two experienced amaurosis fugax for 2-3 weeks at 2 and 24 weeks; scanning showed that the sites of both endarterectomies had become occluded. Ultrasound assessment at 2 weeks showed that 43 of 61 (70.5 per cent) endarterectomized arteries were widely patent. There were three occlusions, one stenosis of greater than 75 per cent, three stenoses of greater than 50 per cent and eleven stenoses of less than 50 per cent. At 6 months a total of five vessels were occluded, with greater than 75 per cent stenosis in three and greater than 50 per cent stenosis in eight. At latest follow-up, six of eight arteries with greater than 50 per cent stenosis shown earlier had scans which had reverted to normal. Tacking down of the distal intima was associated with higher incidence of restenosis and occlusion (P less than 0.01). Women were more predisposed to restenosis by neointimal hyperplasia (P less than 0.05). All restenosis occurred within the first 6 months postoperatively (26.2 per cent) and fell to 16.4 per cent at the end of the study.

Intravenous digital subtraction angiography and duplex ultrasonography in postoperative assessment of carotid endarterectomy

Seventy-four consecutive patients who had undergone carotid endarterectomy procedures were examined with intravenous digital subtraction angiography (IV-DSA) and duplex ultrasonography (DUS) at intervals ranging from 1 to 14 months postoperatively. Ninety-one percent of the DUS and 74% of the DSA images were of diagnostic quality. The two modalities agreed in the assessment of the endarterectomy appearance in 84% of the arteries, with 85% showing no evidence of significant residual disease. There were no arteries with severe restenosis or complete occlusion. In the 10 vessels in which the two modalities disagreed in disease assessment, the IV-DSA images were often degraded by artifact or vessel overlap leading to underestimation of disease. The authors conclude that DUS is the examination of choice for routine follow-up studies of carotid endarterectomy.

Recurrent versus residual carotid stenosis. Incidence detected by Doppler ultrasound

A sterile Doppler probe was used for intraoperative monitoring of the integrity of carotid endarterectomy of 125 vessels of 107 patients. Our objective was to reduce the contribution of residual carotid lesions to recurrent stenosis, which was evaluated by Doppler spectrum analysis in the early (less than 3 months, 66 arteries) and late (3-77 months, mean 32 months, 47 arteries) postoperative period. Intraoperative Doppler monitoring detected residual occlusion in six (4.8%) external carotid arteries and stenosis in ten (8.0%) internal carotid arteries permitting selected arteriography and correction of all significant lesions. Follow-up revealed one (1.5%) asymptomatic common carotid occlusion at 6 weeks and three (6.4%) asymptomatic internal carotid stenoses at 6, 10 and 25 months after operation. When compared to previous published experience, these results suggest that intraoperative correction of residual carotid obstruction detected by Doppler ultrasound may reduce the incidence of postoperative "recurrent" carotid stenosis.

Recurrent carotid stenosis. Results and complications of 57 operations

Among 1992 patients undergoing carotid endarterectomy from January 1972 through December 1984, 57 operations were performed in 51 patients for recurrent carotid stenosis. Thirty-four of these cases had undergone initial surgery at this institution while 23 had endarterectomy elsewhere. Fifty-two of the 57 operations were for symptomatic disease while five were for evidence of a progressing lesion. All operative procedures were monitored with intracerebral blood flow measurements and continuous electroencephalograms. Twenty-three patients required intraoperative shunting. There were no complications related to shunt usage or to the period of temporary occlusion in patients who did not require shunting. Recurrent stenosis was related to intimal hyperplasia in 14 cases, recurrent atherosclerosis with interluminal thrombi or degenerated plaque in 27, unexplained soft thrombus in eight, proximal scarring in six, and to aneurysms in two. Intimal hyperplasia was the most common cause for restenosis within 2 years from the date of surgery and developed earlier in patients with a primary closure than in patients closed with a patch graft. The operative complication rate was 10.5% or 4 times the risk of surgery for primary atherosclerosis at this institution. Complications were attributed primarily to intraoperative and postoperative thromboembolic events related to apparent increased thrombogenicity of these vessels. The highest complication rate occurred in the group of patients undergoing surgery for thrombotic material in the internal carotid artery, either primary or with underlying atherosclerosis. There were no neurological complications in the group with myointimal hyperplasia. The authors' experience suggests that on-lay patch grafting without endarterectomy should be used in patients with myointimal hyperplasia. Patients with complicated recurrent atherosclerosis can be treated with endarterectomy and patch grafting, but interposition vein grafts should be considered in cases in which the vessels are extensively damaged by the recurrent plaque or with an unexplained thrombus at the site of previous endarterectomy.

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.

Incidence of recurrent or residual stenosis after carotid endarterectomy

The incidences of recurrent and residual stenosis after carotid endarterectomy have been controversial. Duplex scanning has recently provided an accurate noninvasive method of quantifying areas of arterial narrowing, and this technique was used in 122 postendarterectomy vessels from 71 men and 35 women with a mean age of 65.2 years. The average time interval between operation and scanning was 26.3 months (range 1 month to 11.76 years). Postoperative examination of the internal carotid artery revealed no stenosis in 78 vessels, less than 50 percent area reduction in 17 vessels, 50 to 75 percent stenosis in 11 vessels, more than 75 percent area reduction in 9 vessels, and total occlusion in 7 vessels. Thus, 22 percent of the vessels (27 of 122) had total occlusion or more than 50 percent area reduction after carotid endarterectomy. This is a higher rate of recurrent stenosis than was diagnosed by oculoplethysmography, where 7 of 52 vessels (13 percent) had a positive oculoplethysmogram after operation. These data show that the reported incidence of residual or recurrent stenosis after carotid endarterectomy is heavily dependent on the testing method used. Duplex scanning documents a 22 percent frequency of residual or recurrent stenosis, a figure higher than has been reported with less sensitive tests.

Incidence of recurrent stenosis after carotid endarterectomy determined by digital subtraction angiography

The results of recent reports of nonselected patients studied by noninvasive techniques suggest there is a 10 to 36 percent rate of restenosis within the first 1 to 2 years after carotid endarterectomy. In the present study of nonselected patients examined by intravenous digital subtraction angiography, only 6.7 percent of operated vessels had recurrent stenosis with a 50 percent or greater decrease in vessel diameter at a mean of 28.5 months postoperatively. These data, when compared with the results of most noninvasive studies, suggest that many of the early lesions regress after 1 to 2 years, as suggested by Zierler et al [8] or that there is a true difference in the rates of restenosis between centers, possibly due to subtle differences in surgical technique or patient risk factors, or both. A symptomatic recurrence rate of only 2.7 percent and a 6.7 percent overall rate of hemodynamically significant recurrent stenosis support the conclusions from earlier and larger series that carotid endarterectomy is a highly effective and durable operation. Although it is important that research centers continue to study the natural history of carotid artherosclerosis and serial changes after carotid endarterectomy, these results suggest that for routine clinical follow-up, frequent and expensive periodic tests to detect recurrent stenosis may not be warranted.

Post-endarterectomy carotid ultrasonic duplex scanning concordance with contrast angiography

The results of ultrasonic duplex scanning combined with spectral analysis are compared with the results of contrast angiography in patients after endarterectomy in which recurrence of carotid arterial disease was suspected. Thirty-six patients underwent a duplex scan study within 3 months of their post-operative angiogram, performed at their physician's discretion (44 studies). The overall accuracy of the method was 80%. Our ability to predict a greater than 50% diameter reduction along with total occlusion was 94%. The measure of agreement corrected for chance between arteriography and duplex scanning as expressed by the Kappa statistic was 0.675 +/- SE (K) 0.096. This level of agreement compared favorably to that of inter- and intra-observer variability in reading cerebral angiograms. The accuracy reported justifies the clinical use of ultrasonic duplex scanning in the detection of recurrent stenosis after carotid endarterectomy.

Progression of carotid disease after endarterectomy: a Doppler ultrasound study

The clinical prognosis and evolution of carotid lesions after unilateral endarterectomy were determined in 64 patients examined 1 to 13 years after surgery (mean observation period, 6 years). Surgery mainly was confined to symptomatic patients with a stenosis only on the appropriate side. Average annual stroke rate was 1.6% on the operated and 0.8% on the nonoperated side. Direct Doppler examination at follow-up revealed a recurrent stenosis (greater than or equal to 50%) or occlusion in 36% of the operated carotid arteries, not significantly different from the proportion of progressive carotid lesions on the nonoperated side (27%). In total, 43.8% of the patients had developed new lesions in one or both carotid arteries, as compared to previous angiographic findings. About 30% of the progressive lesions were associated with symptoms of transient ischemic attacks or stroke, as opposed to 5.5% of vessels without progression of lesions (p less than 0.001). The incidence of recurrent stenosis on the operated side is considerably higher than that previously reported for symptomatic recurrent stenosis, but may represent the natural course of carotid disease in this population, in which carotid surgery thus should not be regarded as definitive treatment.

Screening for significant carotid stenosis by ocular pneumoplethysmography

Carotid stenosis is significant when the resulting lumen is 50 per cent or less of the diameter of the vessel distal to the carotid sinus. The ocular pneumoplethysmograph can detect these stenoses with an accuracy of 97 per cent.