Evaluation of the self-expanding effect of carotid stents in the early postoperative period

PURPOSE

To evaluate the expansion effect of self-expandable stents during the first week after carotid artery stenting (CAS) procedure and to examine the variation of the effect according to the carotid plaque type.

METHODS

Seventy stenotic carotid arteries of 69 patients were stented by using self-expanding Wallstents with diameters of 7 and 9 mm, after detection of stenosis and plaque type by Doppler ultrasonography. Post-stent aggressive ballooning was avoided and residual stenosis rates were measured with digital subtraction angiography. After the stenting procedure, the caudal, narrowest, and cranial diameters of stents were measured with ultrasonography at 30 min, first day and first week. Stent diameter increase and change according to plaque type were evaluated. Two-way repeated measure ANOVA test was used for statistical analysis.

RESULTS

A significant increase was observed in the mean stent diameter in the three stent regions (caudal, narrow, and cranial) from the 30th minute to the first and seventh days (p < 0.001). The most prominent stent expansion occurred in the cranial and narrow segments within the first day. In the narrow stent region; Stent diameter increase between 30th minute-first day, 30th minute-first week, and first day-first week were all significant (p < 0.001). At 30 min, first day, and first week, no significant difference was detected between plaque type and stent expansion in caudal, narrow, and cranial regions (p = 0.286).

CONCLUSION

We think that keeping the lumen patency limited to 30% residual stenosis after CAS procedure by applying minimal post-stenting balloon dilatation and leaving the remaining lumen expansion to the self-expanding feature of the Wallstent might be a sensible approach in order to avoid embolic events and excessive carotid sinus reactions (CSR).

Percutaneous Stenting of the Internal Carotid Artery: The European CAST I Study

Purpose:

To report the results of a multicenter safety trial of percutaneous carotid stenting performed by vascular surgeons.

Methods:

Symptomatic or asymptomatic patients ≥ 65 years of age with internal carotid artery (ICA) stenoses ≥ 70% and ≤ 2-cm long were eligible for enrollment. The procedures were performed in an operating room with the choice of anesthesia and the percutaneous access site at the discretion of the surgeon. Only Palmaz stents were used.

Results:

From January 1, 1996 to December 31, 1997, 99 patients (74 men, mean age 70 years, range 51 to 94) were enrolled in the study. More than half (57 of 99 patients) were asymptomatic. The direct cervical approach was used predominantly (97%). Three (3%) cases were converted to surgery for inability to access the artery or deploy the stent (technical success 97%). No perioperative death or myocardial infarction was reported. Six (6%) procedural complications included 1 reversible arterial spasm, 2 dissections, 1 cervical hematoma, and 2 residual stenoses. One neurological event reversed within 7 days(1% minor stroke rate) and 4 (4%) transient ischemic attacks resolved within 24 hours. One (1%) asymptomatic early occlusion occurred 2 days postoperatively. No neurological event was observed in the 1- to 24-month follow-up (mean 13 months). Two (2%) patients died of nonprocedurally related causes. No stent compression was seen, but 1 asymptomatic occlusion and 3 asymptomatic, non-flow-limiting restenoses (2 < 40%, 1 at 60%) were found within 1 year (3% restenosis rate on an intention-to-treat basis). Patency was 98% at 1 year.

Conclusions:

The results of this trial support the contention that carotid stenting of short ICA lesions can be performed with a low neurological complication rate.

Endovascular Treatment for Internal Carotid Stenoses

Seventy four cases of internal carotid stenoses greater than 60% were treated by PTA and/or stenting 86 times. Sixty one cases of cervical ICA stenosis were treated 71 times. 11 cases of high cervical - intracranial ICA stenosis were treated 13 times. Two cases of ICA dissection were treated by stent deployment.

Stenotic ratio reduced from 79% to 29% in cervical ICA stenosis and 71 % to 32% in high cervical to intracranial ICA stenosis in average. Morbidity related to PTA and/or stenting was 2/74 (2.7%) and mortality was 0%. One was an ischemic complication and the other was a hemorrhagic complication due to hyperperfusion. Restenosis (stenosis greater than 70%) rate was 32%. Asymptomatic cerebral embolism were found in three cases (4.2%) on angiogram immediately after PTA and/or stenting. The complication rate related to PTA and/stenting was low but asymptomatic emboli were found in three cases.

Considering these results, the indication for PTA and/stenting should be restricted to patients with high risk group, such as cases with high medical risks or difficult CEA cases, if appropriate protective systems for cerebral emboli were not available.

Procedural outcome and midterm result of carotid stenting in high-risk patients

Carotid endarterectomy is the standard treatment for carotid stenosis, but carotid artery stenting has emerged as a potential alternative. Elective carotid artery stenting was performed in 42 patients aged 42 to 79 years (mean, 67.05 +/- 8.67 years) after ultrasonography, computed tomography, magnetic resonance angiography and a neurological evaluation. There was bilateral carotid stenosis in 23 patients (55%), with > 90% stenosis in 18 vessels. All patients had significant associated coronary lesions. An emboli protection device and self-expanding stents were used. One year later, the patients were evaluated by Doppler sonography and selective angiography. Technical success was achieved in all procedures. During follow-up, 1 (2.4%) patient died from myocardial infarction, 1 underwent coronary artery bypass and 14 (40%) had minor complaints including occasional dizziness. No other neurological events were noted. Restenosis was found in one case, but selective angiography ruled out a significant lesion. One patient suffered embolization, but recovered completely within 24 hours. In 7 (17%) patients with type C arch interruption and a tortuous carotid course, stenting was successful and they had no embolization or restenosis. Carotid artery stenting is recommended in high-risk patients.

Technique and Clinical Results of Carotid Stenting under Distal Protection

SUMMARY

We perfomed carotid artery stenting(CAS) in 215 patients from August 1997 to October 2003 mainly using the distal protection technique. Our technique and clinical results are described in this paper.

Detection of Unstable Plaques in Patients with Carotid Stenosis using B-Mode Ultrasonography

SUMMARY

Distal embolism is a detrimental complication of stent placement for the carotid artery stenosis. To evaluate usefulness of B-mode ultrasonography (US) for the detection of unstable plaques in patients with carotid artery stenosis, we examined US in 46 arteries of 35 patients with carotid stenosis of > 30%. The echogenicity of 46 carotid plaques was hyperechoic in 20 plaques, hypoechoic in 15, and mixed-echoic in 11. The echogenicity of carotid plaques was correlated with severity of carotid stenosis, ipsilateral stroke or TIA, heart attack, and risk factors of systemic atherosclerosis. Hypoechoic plaques were associated with severe carotid stenosis and ipsilateral ischemic event. Mixed-echoic plaques had a high incidence of past history of heart attack. Hyperechoic plaques were less likely to associate with risk factors of systemic atherosclerosis. We developed a new method of echodensity analysis. Using a computer software, echodensity values of seven plaque components were determined by comparing US findings and pathology of surgical specimens. The echodensity value was defined as a relative value to the arterial lumen. The calcified part of plaques had the highest echodensity of 6.24 +/- 0.86 (mean +/- 2 S.D.); fibrosis or hyarynoid degeneration of 2.05 +/- 0.40, foamy histiocytes of 1.47 +/- 0.05, necrosis of 1.32 +/- 0.16, cholestelin clefts of 1.28 +/- 0.13, intraplaque hemorrhage of 1.02 +/- 0.09, and intraluminal thrombus of 1.27 +/- 0.07. Constructed from the echodensity value, an echo-densitometry color mapping of the carotid plaque illustrated the exact location and extent of plaque component. B-mode US of carotid plaques represents clinical characteristics relating distal embolism and systemic atherosclerosis. A new method of echodensity analysis and echo-densitometry color mapping of the carotid plaque is useful to detect unstable plaques in patients with carotid stenosis.

Biocompatibility and performance of the Wallstent and several covered stents in a sheep iliac artery model

PURPOSE

To compare the biocompatibility and performance of various stent-grafts to those of a bare stent in an ovine model with a subchronic (3 months) endpoint.

MATERIALS AND METHODS

Three different types of stent-grafts (ePTFE/nitinol, n = 8; polyester/nitinol, n = 8; and polycarbonate urethane/cobalt-alloy, n = 8) and a bare stent as a control (Ni-Co-Ti-steel-alloy, n = 8) were implanted in the iliac arteries in eight female sheep. One type of each stent-graft was implanted per animal, two implants at each side. The implantation sites for each type varied from animal to animal. Angiographic control and intravascular ultrasound (IVUS) imaging were performed before and after implantation, after 2 months, and before explantation at 3 months and were used to characterize patency and to assess intimal hyperplasia. After 3 months, the implants were retrieved and subjected to histologic evaluation (after methacrylate embedding, cutting, and histologic staining) to characterize the biologic response.

RESULTS

Implantation was technically successful in all procedures. At 2 and 3 months after implantation, all segments in which stents had been implanted were patent. Marked neointima formation was found in the polyester-covered stent-graft that showed significant luminal narrowing of 50%, compared to the ePTFE-covered (24%) and polycarbonate urethane-covered endoprostheses (22%), as well as the bare stent (Wallstent; 9%; P < .001). A minimal inflammatory vessel wall reaction was demonstrated for the polyester-covered and ePTFE-covered endoprostheses; the polycarbonate urethane-covered stent-graft's response was demonstrable but not significantly different from that of the Wallstent. At 3 months, the ePTFE-covered stent-graft showed incomplete (>90%) endothelial coverage; in the other endoprostheses, complete but partially immature endothelialization was found.

CONCLUSION

All stent-grafts induced an inflammatory vessel wall reaction with neointimal hyperplasia. The polyester-covered endoprosthesis caused a marked reaction with 50% luminal stenosis. Endothelialization was retarded with the ePTFE-covered stent-graft. The bare stent performed best in regard to neointimal formation and caused the least inflammatory response.

Carotid artery stenting in patients with high-risk anatomy for carotid endarterectomy

PURPOSE

To report the results of carotid artery stenting (CAS) in patients considered to have high-risk anatomical characteristics for carotid endarterectomy.

METHODS

CAS was performed in 39 carotid arteries of 37 consecutive patients (26 men; mean age 72 +/- 8 years, range 56-88) who met the criteria for high-risk surgical anatomy: previous ipsilateral carotid endarterectomy (20/39, 51.3%), common carotid bifurcation above the mandibular angle (5/39, 12.8%), contralateral carotid artery occlusion (15/39, 38.5%), or previous radiation therapy to the neck (1/39, 2.6%). Palmaz, Integra, or Wallstents were deployed via a percutaneous femoral artery access. Independent neurological evaluation was performed at specified time points, and a dedicated committee adjudicated all clinical events.

RESULTS

Procedural success was 100%, with no major in-hospital complications. Neurological events were rare. Only 1 (2.6%) transient ischemic attack occurred prior to discharge; at 30 days, 1 (2.6%) additional minor stroke had been observed, giving a 2.6% cumulative 30-day "death plus any stroke" rate. Over a mean 11 +/- 6-month follow-up, 2 (5.4%) patients died of nonneurological causes, but there were no strokes.

CONCLUSIONS

CAS is a viable endovascular revascularization technique that can be performed safely and effectively in patients with high-risk anatomy for carotid endarterectomy.

Endovascular Surgery for Internal Carotid Stenoses. Results of PTA vs. Stenting

SUMMARY

This paper will overview our results of endovascular therapy (PTA or stenting) for cervical ICA stenosis and discuss the advantages and disadvantages of each treatment. 60 cases with 62 lesions were treated with PTA 68 times, while 36 cases with 37 lesions were treated with stenting 37 times. A total of 99 lesions were treated with PTA or stenting 105 times. In the PTA group arterial stenosis improved from 76.4% to 21%. In the stent group the stenosis improved from 82.3% to 8.3%. The morbidity rate was 2/60 (3.3%) in PTA group, although two cases had minor neurological deficits, while in stent treated group, morbidity rate was 1/36 (2.8%), although it showed one major neurological deficit. Mortality was 0% in each group. The restenosis rate in PTA group was 15/58 (26%), while it was 0/20 (0%) in stent treated group. Stenting brings significant reduction of stenosis and reduces the rate of restenosis compared to PTA. However, stenting has its own disadvantages such as hypotension and distal kinks when deployed in tortuous ICA stenosis.

The strategy for internal carotid stenosis with thrombus

SUMMARY

We report 3 cases of internal carotid artery (ICA) stenosis with thrombus. The initial symptom is transient ischemic attack (TIA) in 1 case, and cerebral infarction due to artery-to-artery embolism in 2 cases.We started anticoagulation and antiplatelet therapy after the angiography on admission in all cases. Carotid endarterectomy (CEA) was performed in 1 case after confirming the disappearance of the thrombus 1 month after the initial attack, although small cerebral embolic infarction happened during this period. In the other cases, percutaneous transluminal angioplasty (PTA) and stenting was performed using the protective technique about 2 weeks after the initial attack without embolic complication. Postoperative angiography showed sufficient dilatation. It seemed that PTA/stenting using the protection system was one of the alternatives for ICA stenosis with thrombus.

Safety, efficacy, and durability of carotid artery stenting for restenosis following carotid endarterectomy: a multicenter study

PURPOSE

To present the results of a multicenter registry established to collect data on carotid stent procedures in patients with restenosis following carotid endarterectomy.

METHODS

The procedural details, outcomes, and late follow-up results were collected from 14 centers in the United States. Thirty-day and late stroke and death rates were analyzed.

RESULTS

Three hundred and thirty-eight patients (201 men; 71 +/- 8 years) underwent carotid stenting in 358 arteries. The average duration from carotid endarterectomy was 5.5 +/- 7.3 years. Sixty-one percent of the patients were asymptomatic. The overall 30-day stroke and death rate was 3.7%. The minor stroke rate was 1.7% (6/358), and the major nonfatal stroke rate was 0.8% (3/358). The fatal stroke rate was 0.3% (1/358), and the nonstroke-related death rate was 0.9% (3/338). There was 1 (0.3%) fatal and 1 (0.3%) nonfatal stroke during the follow-up period. The overall 3-year rate of freedom from all fatal and nonfatal strokes was 96% +/- 1% (+/- SE).

CONCLUSIONS

Carotid artery stenting can be performed in patients with restenosis following carotid endarterectomy with 30-day complication rates comparable to those of most published studies on repeat carotid endarterectomy. Results of late follow-up suggest that this technique is durable and efficacious.