Endarterectomy Site Research Articles

Anatomic patterns of carotid endarterectomy healing

Restenosis after carotid endarterectomy is a dynamic process likely influenced by surgical technique as well as by anatomic, hemodynamic, and patient factors. To characterize the healing of carotid endarterectomy sites, intraoperative and serial postoperative color duplex scans were performed in 126 patients (136 repairs). Vessel-wall imaging, midstream spectral analysis, and measurements of diameter and cross-sectional area from common carotid artery (CCA) and internal carotid artery (ICA) segments were compared (at 3, 6, 15, and 30 months) and severity of lumen stenosis was determined. After primary closure (n = 15), patch angioplasty (n = 121), or intraoperative revision based on duplex scanning (n = 5), 12 repairs had mild residual flow abnormalities and 1 repair had a moderate flow abnormality. Mean ICA bulb diameter was greater in patched repairs (0.81 cm, range 0.6 to 1.1 cm) than primary closed repairs (0.7 cm, range 0.45 to 0.8 cm). No ICA occluded during follow-up (mean 24 months), and three repairs, two in the ICA and one in the CCA, demonstrated 50% to 75% diameter reduction at 9 months. Lumen cross-sectional area of vein-patched repairs increased 0.6 cm2 to 0.76 cm2 (P < 0.01) in the ICA and 0.69 cm2 to 1.1 cm2 (P < 0.01) in the CCA segments by 3 months compared with intraoperative measurement. Four patients with progressive dilatation of the patch segment to a mean of 1.77 cm2 developed asymptomatic posterior wall mural thrombus. Postoperative blood flow velocities measured through the repair were similar to intraoperative values. Minor intraoperative hemodynamic abnormalities were not associated with the development of restenosis, and changes in repair site anatomy occurred within 3 months with little change thereafter. We have found intraoperative scanning useful for detection of anatomic defects and associated turbulence, lesions that should be immediately corrected. Surgical technique that achieves normal intraoperative carotid flow hemodynamics and B-mode ultrasonic vessel wall appearance should predict an endarterectomized segment free of significant residual plaques and neointimal hyperplasia. Tailoring of the vein patches to achieve lumen diameters < 1 cm is recommended because of the dilataton likely to develop after surgery that may lead to vessel wall mural thrombus.

Carotid artery bypass in acute postendarterectomy thrombosis

Carotid endarterectomy has demonstrated excellent results over the past 2 decades with combined stroke mortality of < 4% in most active centers. However, the optimal technique for surgical reconstruction for patients with acute postoperative deficits is more controversial. In the last 10 years (1985 to 1995), we performed 1,267 carotid endarterectomies, with 17 strokes (1.3%) and 16 deaths (1.2%). Twenty-four patients developed acute (within 72 hours) postoperative neurologic deficits. In 10 patients, the carotid artery was confirmed patent by duplex scan or angiography, and the neurologic deficit resolved without further therapy. Early reexploration was performed in 14 cases for suspected thrombosis associated with a new neurologic deficit. In each case, resection of the endarterectomy site and an interposition bypass was performed with greater saphenous vein (11), jugular vein (2), or polytetrafluoroethylene (2) grafts. (One patient required a new bypass for acute occlusion of the initial vein bypass.) Postoperatively, 8 patients had complete resolution of their deficit, 3 had minimal residual deficits, and 3 suffered permanent stroke. However, 2 of these patients died. Carotid artery bypass with exclusion of the endarterectomy site resulted in improvement in symptoms in 79% (11 of 14) of the patients and complete resolution in 57% (8 of 14). In long-term follow up (1 to 41 months), there have been no occlusions and one restenosis requiring revision at 11 months. Carotid artery bypass can be performed safely with acceptable results. The use of autogenous venous conduits allows reconstruction with an endothelial lined conduit that may improve results in patients with acute postoperative neurologic deficit secondary to thrombosis of the endarterectomized carotid artery.

Intraoperative duplex scanning as a means of quality control during carotid endarterectomy

To identify correctable technical errors following carotid endarterectomy using intraoperative colour duplex sonography (ATL, UM9, HDI). Results were compared with intraoperative flow measurements using an operative flow meter and with middle cerebral artery velocity measured by trans-cranial Doppler (TCD). Prospective study. 50 consecutive patients undergoing carotid endarterectomy were investigated. Follow-up was performed at 6 weeks using duplex scanning and clinical evaluation. Significant intraoperative technical errors were detected in three patients and were re-explored. Two scans demonstrated kinking or pinching at the distal endarterectomy site requiring patch-plasty and the third revealed a large mass of intramural thrombus. A further 18 endarterectomies yielded 21 additional minor abnormalities. Duplex sonography provides a sensitive intraoperative technique for detecting thrombus and technical errors. It yields both anatomic and hemodynamic details and is superior to intraoperative flow measurements and transcranial doppler.

Effects of Completion Angiography on the Outcome of Carotid Endarterectomy

The carotid endarterectomy results of a single surgeon were analyzed over an 8-year period to determine how routine completion angiography affected endarterectomy outcome. Completion angiography was performed in 80% of cases. A total of 145 patients (86%) were symptomatic while 23 (14%) were symptom-free. Of 131 completion angiographies performed, 94 were interpreted as normal and 37 abnormal. The arteries were reopened In 23 patients with abnormal results. In the 14 patients with abnormal angiograms who were not reopened, two showed no flow into the internal carotid artery and the vessels were ligated. The remaining 12 patients had abnormalities in the external carotid artery or normal Doppler signals along the common carotid artery and internal carotid artery segments. Among the 37 patients with abnormal angiograms, arteries were re-explored in four; there were no neurologic complications. In the entire group, there were three mortalities, one stroke, one transient ischemic attack, two wound complications, four myocardial infarctions, two occurrences of cerebral edema, two pneumonias and nine transient local nerve injuries. Completion angiography has allowed an improved technique while also enhancing the ability to identify technical problems during surgery without increasing morbidity. These results support the use of intraoperative completion angiography to evaluate carotid endarterectomy sites.

Effects of completion angiography on the outcome of carotid endarterectomy

The carotid endarterectomy results of a single surgeon were analyzed over an 8-year period to determine how routine completion angiography affected endarterectomy outcome. Completion angiography was performed in 80% of cases. A total of 145 patients (86%) were symptomatic while 23 (14%) were symptom-free. Of 131 completion angiographies performed, 94 were interpreted as normal and 37 abnormal. The arteries were reopened in 23 patients with abnormal results. In the 14 patients with abnormal angiograms who were not reopened, two showed no flow into the internal carotid artery and the vessels were ligated. The remaining 12 patients had abnormalities in the external carotid artery or normal Doppler signals along the common carotid artery and internal carotid artery segments. Among the 37 patients with abnormal angiograms, arteries were re-explored in four; there were no neurologic complications. In the entire group, there were three mortalities, one stroke, one transient ischemic attack, two wound complications, four myocardial infarctions, two occurrences of cerebral edema, two pneumonias and nine transient local nerve injuries. Completion angiography has allowed an improved technique while also enhancing the ability to identify technical problems during surgery without increasing morbidity. These results support the use of intraoperative completion angiography to evaluate carotid endarterectomy sites.

Intraoperative Assessment of Carotid Endarterectomy: A Comparison of Techniques

Routine intraoperative imaging of the carotid artery following carotid endarterectomy can detect defects at the site of endarterectomy that may lead to neurologic morbidity. A number of methods have been used to evaluate the completed endarterectomy. In this prospective study we compared subjective methods of assessment (hand-held, continuous-wave Doppler imaging with audible interpretation of signals) and objective methods of assessment (duplex ultrasonography with color flow and digital subtraction arteriography) with respect to their ability to detect operative abnormalities. Fifty-three carotid endarterectomies were evaluated by means of all methods of assessment. Six patients had significant abnormalities in which the vessel was reopened and the abnormality confirmed. The sensitivity and specificity for detecting abnormalities for each method are, respectively: duplex ultrasonography with color flow, 100% and 100%; digital subtraction arteriography, 66% and 95.7%; and continuous-wave Doppler imaging with audible interpretation of signals, 16% and 97.8%. There was one (1.8%) operative carotid neurologic complication during the postoperative period and follow-up (stroke due to vein patch rupture on postoperative day 2). These data suggest that an objective rather than a subjective method of assessing carotid endarterectomy is more useful in detecting operative abnormalities and that duplex ultrasonography with color flow is as useful as digital subtraction arteriography.

Successful Treatment of an Acute Thrombosis of an Intracranial Vertebral Artery Endarterectomy with Urokinase

THIS IS A case report of a 47-year-old man admitted with a 7-month history of disequilibrium, multiple reversible vertebrobasilar ischemic attacks, and one submaximal completed stroke in the left posterior inferior cerebellar artery distribution. Vertebrobasilar ischemic attacks continued despite anticoagulation, and orthostatic symptomatology suggested a significant hemodynamic component contributing to the posterior circulation ischemia. Angiography confirmed bilateral high-grade stenoses of the intracranial vertebral arteries. A right intracranial vertebral artery endarterectomy was performed with electroencephalographic and somatosensory evoked potential monitoring and protection with barbiturate infusion. The arteriotomy was closed with a vein patch. Postoperatively, the endarterectomy site thrombosed. This thrombosis was completely reversed with 220,000 U of urokinase selectively infused intra-arterially at the site of thrombosis. This procedure was not complicated by hemorrhage or distal embolization. The vertebral artery was confirmed to be patent 24 hours and 7 days after the urokinase injection. The patient sustained a borderzone infarction in the right cerebellar hemisphere without neurological deficits and was discharged home well.

Initial experience with intravascular ultrasound imaging during carotid endarterectomy.

To assess the feasibility of intravascular ultrasound imaging during carotid endarterectomy. Intravascular ultrasound imaging was performed during carotid endarterectomy in eight patients using an over-the-wire catheter system with a 30-MHz ultrasound probe. In vitro studies were carried out before the intraoperative application, paying special attention to visualization of the wall layers of normal carotid arteries, structures of more or less diseased vessels, and surgically placed materials such as patch, suture material, and fibrin glue. Although intravascular ultrasound failed to distinguish between intima and media in areas of normal intima, fibrotic and calcified plaques were detected clearly. Dacron patch as well as sutures were identified as highly reflective structures. In seven of the eight patients studied, intravascular ultrasound yielded cross-sectional images of good quality allowing identification of the vessel layers and the structures at the endarterectomy site. In all patients the three layers of the vessel wall were clearly differentiated and the transition zone between the site of endarterectomy and the genuine vessel appeared smooth without intimal flaps or residual arteriosclerotic plaques. In one patient severe eccentric thickening of the media was detected in the distal internal carotid artery. Neither damage of the vessel layers by the shunt nor thrombus formation in the operating area and the internal carotid artery were detected. Intravascular ultrasound lends itself as a potentially valuable method of quality control during carotid endarterectomy. The method seems to enable an accurate evaluation of the endarterectomy site and the search for residual plaques.

The importance of intraoperative detection of residual flow abnormalities after carotid artery endarterectomy

The efficacy of carotid endarterectomy in the prevention of strokes mandates low perioperative morbidity, as well as a low incidence of late ipsilateral stroke. This prospective study involving 430 patients (461 carotid endarterectomies) correlated the results of intraoperative assessment with end points of stroke and residual/recurrent internal carotid artery (ICA) stenosis. Adequacy of the repair was assessed by ultrasound studies (duplex scan and pulsed Doppler spectral analysis) alone (n = 142), ultrasound studies and arteriography (n = 268), or clinical inspection (n = 51). After operation, duplex ultrasonography was used to confirm patency and categorize severity of ICA stenosis. At operation 26 carotid endarterectomy sites (5.6%), were revised based on intraoperative studies. Perioperative (30-day) morbidity rates were similar in patients with normal, mildly abnormal, or no ultrasound completion studies. There were six permanent (1.3%) and 12 temporary (2.6%) neurologic deficits and six deaths, including four fatal strokes and two fatal myocardial infarctions. By life-table analysis, the incidence of greater than 50% diameter-reducing ICA stenosis or occlusion was increased (p < 0.007, log-rank test) in patients with residual flow abnormality or no study. More important, patients with normal intraoperative flow studies had a significantly lower rate of late ipsilateral stroke compared with the remaining patient cohort (p = 0.04, log-rank test). During the mean 30-month follow-up interval, the incidence of late stroke was increased (p = 0.00016) in patients with ICA restenosis or occlusion (3/35) compared with patients without recurrent stenosis (3/426). Confirmation of a normal repair at operation affords the best opportunity to minimize ischemic neurologic events and anatomic restenosis after carotid endarterectomy.

The importance of intraoperative detection of residual flow abnormalities after carotid artery endarterectomy

Purpose: The efficacy of carotid endarterectomy in the prevention of strokes mandates low perioperative morbidity, as well as a low incidence of late ipsilateral stroke. This prospective study involving 430 patients (461 carotid endarterectomies) correlated the results of intraoperative assessment with end points of stroke and residual/recurrent internal carotid artery (ICA) stenosis.Methods: Adequacy of the repair was assessed by ultrasound studies (duplex scan and pulsed Doppler spectral analysis) alone (n = 142), ultrasound studies and arteriography (n = 268), or clinical inspection (n = 51). After operation, duplex ultrasonography was used to confirm patency and categorize severity of ICA stenosis. At operation 26 carotid endarterectomy sites (5.6%), were revised based on intraoperative studies.Results: Perioperative (30-day) morbidity rates were similar in patients with normal, mildly abnormal, or no ultrasound completion studies. There were six permanent (1.3%) and 12 temporary (2.6%) neurologic deficits and six deaths, including four fatal strokes and two fatal myocardial infarctions. By life-table analysis, the incidence of greater than 50% diameter-reducing ICA stenosis or occlusion was increased (p < 0.007, log-rank test) in patients with residual flow abnormality or no study. More important, patients with normal intraoperative flow studies had a significantly lower rate of late ipsilateral stroke compared with the remaining patient cohort (p = 0.04, log-rank test). During the mean 30-month follow-up interval, the incidence of late stroke was increased (p = 0.00016) in patients with ICA restenosis or occlusion (3/35) compared with patients without recurrent stenosis (3/426).Conclusion: Confirmation of a normal repair at operation affords the best opportunity to minimize ischemic neurologic events and anatomic restenosis after carotid endarterectomy.

Interruption of vascular thrombus formation and vascular lesion formation by dietary n-3 fatty acids in fish oil in nonhuman primates.

Because of discrepant claims regarding the relative biological effects of n-3 fatty acids (n-3FAs), we have concurrently measured the effects of dietary n-3FAs on blood and vascular lipid composition, hemostatic function, blood thrombotic responses, vascular thrombus formation, and vascular lesion formation in baboons. Dietary n-3FAs displaced n-6FAs in plasma, platelets, blood vessels, and corresponding urinary eicosanoid metabolites (p < 0.01 in all cases) within weeks after initiation of a semipurified diet containing 1 g/kg per day n-3FA-ethyl ester concentrate (composed of two thirds eicosapentanoic acid and one third docosahexanoic acid). Coincidentally, platelet hemostatic function became minimally impaired (template bleeding times prolonged from 4.3 +/- 0.5 minutes to 7.6 +/- 1.3 minutes, p = 0.039); concentrations of collagen producing half-maximal platelet aggregation increased (from 6.4 +/- 2.1 to 8.5 +/- 2.5 micrograms/mL, p = 0.045); and tissue factor expression by endotoxin-stimulated blood monocytes fell (from 6.5 +/- 1.2 to 1.7 +/- 0.14 mU/10(6) cells, p < 0.005). Dietary n-3FAs decreased deposition of platelets onto thrombogenic segments of Dacron vascular graft incorporated into chronic exteriorized femoral arteriovenous (AV) shunts, a thrombotic process resistant to the effects of both aspirin and heparin (111In-labeled platelet deposition decreased from 14.1 +/- 1.4 x 10(9) platelets/5-cm segment at 40-60 minutes with occlusion to 7.5 +/- 0.8 x 10(9) platelets/5-cm segment without occlusion; p < 0.001). Platelet deposition onto segments of endarterectomized homologous normal aorta in the AV shunts of n-3FA-treated animals was similarly reduced (from 4.4 +/- 0.9 to 1.8 +/- 0.4 x 10(9) platelets; p < 0.01). Dietary n-3FAs interrupted vascular thrombus formation at sites of surgical carotid endarterectomy (platelet deposition, 1.5 +/- 0.4 versus 4.4 +/- 1.0 x 10(9) platelets in untreated controls; p < 0.001). Moreover, endarterectomized aortic segments (EASs) from n-3FA-treated donors exhibited little capacity to induce thrombus formation when tested in the AV shunts of control recipient animals (0.24 +/- 0.10 versus 4.4 +/- 0.90 x 10(9) platelets). However, in the converse crossover experiments, EASs from control animals actively accumulated platelets when studied in the AV shunts of n-3FA-treated animals (1.8 +/- 0.4 x 10(9) platelets; p < 0.01 versus n-3FA-treated EASs in shunts of normal animals). Dietary n-3FAs also abolished vascular lesion formation at sites of carotid endarterectomy 6 weeks after surgery (cross-sectional area of neointima 0.048 +/- 0.031 mm2 compared with 0.428 +/- 0.104 mm2 in control arteries; p = 0.010). In nonhuman primates, dietary n-3FAs in high doses eliminate both vascular thrombus formation and vascular lesion formation after mechanical vascular injury while largely sparing hemostatic function and modestly reducing blood thrombotic responses. These effects are attributed to selective n-3FA-dependent alterations in cellular membrane functions.

Interruption of vascular thrombosis by bolus anti-platelet glycoprotein IIb/IIIa monoclonal antibodies in baboons

Purpose: Because the platelet membrane receptor glycoprotein IIb/IIIa plays a central role in the recruitment of platelets into forming thrombus, therapeutic inhibition of this receptor complex may be particularly useful to prevent thrombosis after small vessel arterial manipulation.Methods: The relative hemostatic safety and antithrombotic efficacy for thrombus formation at sites of endarterectomy and implanted prosthetic vascular graft of a murine monoclonal antibody (LJ-CP8) against platelet glycoprotein IIb/IIIa have been determined in baboons after bolus injections in doses (10 mg/kg) that block platelet receptor function for fibrinogen and other adhesive glycoproteins (absent platelet aggregation and bleeding times > 30 minutes without affecting circulating platelet counts).Results: Thrombus formation was eliminated by LJ-CP8 at sites of surgical endarterectomy in fresh segments of homologous aorta incorporated into chronic exteriorized arteriovenous femoral shunts (accumulation of indium 111-labeled platelets fell from 4.40 ± 0.89 × 109 platelets/cm in control animals [n = 6] to 0.23 ± 0.01 × 109 platelets/cm in treated animals [n = 4]; p < 0.005). The formation of thrombus was also abolished by LJ-CP8 at sites of 1 cm prosthetic vascular grafts (4 mm inner diameter polytetrafluoroethylene grafts) interposed into common carotid arteries (deposition of indium 111-labeled platelets decreased from 2.57 ± 0.43 × 109 platelets/cm [n = 5] to 0.16 ± 0.06 × 109 platelets/cm, [n = 4]; p = 0.004). However, LJ-CP8 injections produced substantial bleeding in the surgical wound during the first few hours after operation. Thirty days after operation all four graft implants were patent in LJ-CP8-treated animals compared with two of five in control animals (p = 0.06).Conclusions: We conclude that profound inhibition of platelet glycoprotein IIb/IIIa receptor function by single bolus injection of LJ-CP8 monoclonal antibody transiently abolishes platelet hemostatic function, eliminates acute thrombus formation at sites of endarterectomy and prosthetic vascular graft implants, and may improve vascular patency.

Combined Carotid Endarterectomy and Coronary Artery Bypass in a Community Hospital

A study examining combined carotid endarterectomy and coronary artery bypass (CAB) outside the metropolitan or university hospital setting was performed. Over a 5-year period, 52 patients underwent carotid endarterectomy and CAB under a single anesthetic. Twenty-two patients (42%) had unstable angina and 23 (44%) had previous neurologic symptoms. There were two postoperative strokes (4%), one ipsilateral and one contralateral to the endarterectomy site. No ipsilateral neurologic events occurred after discharge (mean follow-up 25 months). There were four deaths (8%), all of which were cardiac related. Three of the four deaths were in patients with a recent history of congestive heart failure, a subgroup with a high mortality rate (three of seven; 43%). Over the same period, 2421 patients underwent CAB alone with stroke and mortality rates of 1.4 and 2.0% respectively, while 344 patients had carotid endarterectomy alone with stroke and mortality rates of 0.6 and 0.6% respectively. It is concluded that the combined procedure can be performed in a community setting with morbidity and mortality rates similar to those for major centers. Although stroke and mortality rates for the combined procedure were higher than those for the isolated operations, this group has a high incidence of cardiac symptoms, including unstable angina and congestive heart failure. Patients with recent congestive heart failure had the highest mortality rate of any subgroup and these patients should be carefully examined with regard to selection for the combined procedure.

Polytetrafluoroethylene interposition grafts for carotid reconstruction

Polytetrafluoroethylene interposition grafts were used for carotid reconstruction in 26 operations performed in 23 patients during a 7-year period. There were 10 men and 13 women with a mean age of 66 years. The indication for interposition graft placement was recurrent stenosis with inability to perform endarterectomy in nine operations, a severe kink or technical problem during endarterectomy in nine, aneurysmal changes of the artery in six, and thrombosis of the endarterectomy site segment with stroke in two. There were no perioperative deaths and no further perioperative neurologic complications. Follow-up with performance of yearly duplex scans was obtained in all patients, and the mean duration of follow-up was 36 months. One patient (4%) died of end-stage pulmonary disease during the study interval. Occlusion of the polytetrafluoroethylene graft occurred at 12 months in one patient (4%). Hemodynamically significant restenosis developed in two patients (8%), and two patients (8%) had mild restenosis. Evidence of a second restenosis developed in three of the nine patients who underwent polytetrafluoroethylene interposition graft placement for carotid restenosis. On the basis of our study results, we conclude that polytetrafluoroethylene can be used effectively for carotid reconstruction when an interposition graft is required. However, recurrent stenosis occurs. Patients who undergo polytetrafluoroethylene interposition graft placement for carotid restenosis appear to be at high risk for a second restenosis.

Polytetrafluoroethylene interposition grafts for carotid reconstruction.

Polytetrafluoroethylene interposition grafts were used for carotid reconstruction in 26 operations performed in 23 patients during a 7-year period. There were 10 men and 13 women with a mean age of 66 years. The indication for interposition graft placement was recurrent stenosis with inability to perform endarterectomy in nine operations, a severe kink or technical problem during endarterectomy in nine, aneurysmal changes of the artery in six, and thrombosis of the endarterectomy site segment with stroke in two. There were no perioperative deaths and no further perioperative neurologic complications. Follow-up with performance of yearly duplex scans was obtained in all patients, and the mean duration of follow-up was 36 months. One patient (4%) died of end-stage pulmonary disease during the study interval. Occlusion of the polytetrafluoroethylene graft occurred at 12 months in one patient (4%). Hemodynamically significant restenosis developed in two patients (8%), and two patients (8%) had mild restenosis. Evidence of a second restenosis developed in three of the nine patients who underwent polytetrafluoroethylene interposition graft placement for carotid restenosis. On the basis of our study results, we conclude that polytetrafluoroethylene can be used effectively for carotid reconstruction when an interposition graft is required. However, recurrent stenosis occurs. Patients who undergo polytetrafluoroethylene interposition graft placement for carotid restenosis appear to be at high risk for a second restenosis.

Jugular venous vasopressin increases during carotid endarterectomy after cerebral reperfusion

Several recent reports have suggested that pressor hormones may be released during and after carotid endarterectomy and that release of these factors may be associated with postoperative hypertension and other postoperative morbidity. We measured vasopressin, adrenocorticotropic hormone, and cortisol in jugular venous blood during carotid endarterectomy under general anesthesia in 43 patients with routine carotid shunting. Jugular venous vasopressin increased significantly after the second period of carotid occlusion for shunt removal and remained increased at closure. Vasopressin did not change during the initial carotid occlusion for shunt placement or during the endarterectomy itself, and neither ACTH nor cortisol changed at any sample time. Greater resting vasopressin and cortisol and larger responses of vasopressin were observed in patients receiving phenylephrine to correct intraoperative hypotension. There were no correlations between postoperative hypertension or postoperative complications and intraoperative hormone values. These results suggest (1) basal intraoperative vasopressin values reflect the blood volume of the patient, (2) increased vasopressin was not related to postoperative morbidity, and (3) intraoperative increases in pressor hormones are most likely physiologic responses to specific stimuli such as hypovolemia or hypotension rather than pathologic phenomena. We speculate that the increase of vasopressin after the second carotid occlusion and reperfusion of the brain may be due to the action of humoral factors released into the carotid circulation from the endarterectomy site.

Failure of Aspirin plus Dipyridamole To Prevent Restenosis after Carotid Endarterectomy

To evaluate therapy with aspirin plus dipyridamole in reducing restenosis after carotid endarterectomy. A total of 163 patients having 175 surgical carotid endarterectomies. Eighty-three patients (90 endarterectomies) were randomly assigned to receive oral aspirin, 325 mg, plus dipyridamole, 75 mg, beginning 12 hours preoperatively, followed by a second dose administered within 8 hours after the operation, and given three times daily thereafter for 1 year. Eighty patients (85 endarterectomies) received placebo medication that was identical in appearance to the study drugs. After the adequacy of the surgical procedure was confirmed by intraoperative angiography, restenosis at the endarterectomy sites was evaluated using serial duplex ultrasound studies before hospital discharge and at 3-month intervals postoperatively for 1 year. Based on the time for developing identifiable restenosis and on efficacy analysis, greater than 50% restenosis developed in 11 operated vessels (16%) in the treated group and in 10 arteries (14%) in the placebo group, yielding an observed risk increase of 14% (95% CI, -52% to 167%; P greater than 0.2). By intention-to-treat analysis, greater than 50% restenosis developed in 16 of 90 operated vessels in treated patients and in 10 of 85 arteries in patients receiving placebo (26% for the treated group and 12% for the placebo group; P = 0.18, Mantel-Haenszel statistic), representing an observed risk increase of 110% (CI, -5% to 365%). Similar differences were observed for greater than 20% restenosis and for the comparison of patients rather than operated vessels by either intention-to-treat or efficacy analyses. Because therapy not only failed to reduce carotid restenosis but may have actually increased its frequency, treatment with aspirin plus dipyridamole probably has no clinically important benefit on restenosis in patients having carotid endarterectomy.

Biosynthetic Patch in Carotid Angioplasty

Since early embolic events and recurrent stenosis are, after intraoperative ischemia, the main problems of carotid endarterectomy (CEA), technical im provements that may reduce the incidence of these feared complications are required. The causes of recurrent carotid stenosis may be related to progression of the atherosclerotic disease, to myointimal hyperplasia at the site of endar terectomy, or to technical mistakes during intervention. The choice of patching material seems to be important in preventing late complications. The authors present their original experience with a biosynthetic ovine patch in carotid surgery. In the period from January, 1988, to June, 1989, 211 carotid endarterectomies were performed for atherosclerotic disease at the carotid bi furcation in 176 patients. A primary closure of the carotid arteriotomy was performed in 82 cases and a patch angioplasty was employed in 129. As the material employed in the patch angioplasty, the authors used the biosynthetic ovine patch in 30 cases. No deaths and no permanent neurologic deficits were registered in this series during the awakening and during the postoperative care. One patient died one month after the surgical procedure because of myocardial infarction without neurologic symptoms. These patients were admitted to the prospective study for the evaluation of the carotid that was operated on. The study was performed with clinical and instrumental examinations (duplex scanner). Each patient was seen at months 1, 3, 6, and 12 after surgery. All the patients except 3 had a twelve-month follow-up; by echo tomography a case of nonhemodynamic restenosis was detected in an asymptomatic patient six months after CEA. The authors' preliminary experience with this biosynthetic graft as patching material has been satisfactory. They conclude that this biosynthetic graft, be cause of its handling and particularly its healing characteristics, can be consid ered as a graft material for patching at the carotid level.

単一のチームによる頸動脈内膜剥離術の手術成績

We performed 79 carotid endarterectomies in 72 patients in the last 7 years. This report describes surgical results, complications and follow-up in those endarterectomies. We used internal shunts under barbiturate brain protection in all cases. The mean time for shunt insertion and removal is 3 minutes and 4.5 minutes, respectively. We used surgical microscope and removed plaques as a whole block. The surgical mortality was 2.8% (2 cases) and major morbidity was 2.8% (2 cases). The cause of operative death in two cases was rupture of the suture, which resulted in blood loss and subsequent fatal infarction. One case of major infarction was caused by temporary occlusion of the carotid artery. The bilateral vertebral arteries of this case were occluded, and collaterals were from the carotid artery through the stenotic part. The other case of major infarction was caused by inappropriate collection of the intimal flap and inappropriate usage of the large-sized internal shunt. The follow-up disclosed only one case of infarction occurred in the surgical side, because the patient failed to take anti-platelet drugs. Two cases developed symptomatic restenosis of the endarterectomy site because of myointimal hyperplasia. Complication of endarterectomy can be avoided by careful intra- and postoperative care.

Reduction in thrombus formation by placement of endovascular stents at endarterectomy sites in baboon carotid arteries.

Although antithrombotic therapies with aspirin, dipyridamole, and heparin have decreased thrombo-occlusive events, they have not abolished these complications. Endovascular mechanical support, first reported by Dotter in 1969, has been proposed as a means to reduce both acute and chronic vessel closure by providing a supporting framework for the disrupted and sometimes dissected arterial wall. To determine the effects of placing self-expanding stainless steel wire endoprostheses on the accumulation of thrombus at sites of carotid artery endarterectomy we measured platelet deposition continuously for 90 minutes and at 24 and 48 hours by gamma camera imaging of autologous 111In-labeled platelets in six stented and nonstented endarterectomized baboons that received heparin but no antiplatelet agents. At nonstented endarterectomy sites 5.36 +/- 1.25 x 10(8), 4.78 +/- 0.98 x 10(8), and 4.55 +/- 0.81 x 10(8) platelets per cm were deposited at 30, 60, and 90 minutes, respectively. In contrast, stented endarterectomy sites accumulated 0.99 +/- 0.31 x 10(8), 0.66 +/- 0.33 x 10(8), and 0.80 +/- 0.36 x 10(8) platelets per cm at 30 minutes (p = 0.02), 60 minutes (p = 0.004), and 90 minutes (p = 0.002), respectively. Platelet deposition remained reduced at 24 and 48 hours in stented endarterectomized carotid arteries (ECAs) when assessed as a ratio between net radioactivity in the endarterectomized region versus whole blood radioactivity (p = 0.006 and p = 0.009, respectively). Both stented and nonstented ECAs remained patent acutely, although two of six nonstented ECAs occluded by 30 days. By comparison 11 of 14 nonstented ECAs remained patent in another group of control animals. Scanning electron microscopy of control and stented arteries at 30 days demonstrated equivalently confluent endothelium. We postulate that endovascular stents reduce the thrombogenic effects of flap formation, tearing, dissection, and vasospasm in ECAs.