Michael H. Wholey

Global experience in cervical carotid artery stent placement

The purpose of this article is to review and update the current status of carotid artery stent placement in the world. Surveys to major interventional centers in Europe, North and South America, and Asia were initially completed in June 1997. Subsequent information from these 24 centers in addition to 12 new centers has been obtained to update the information. The survey asked the various questions regarding the patients enrolled, procedure techniques, and results of carotid stenting, including complications and restenosis. The total number of endovascular carotid stent procedures that have been performed worldwide to date included 5,210 procedures involving 4,757 patients. There was a technical success of 98.4% with 5,129 carotid arteries treated. Complications that occurred during the carotid stent placement or within a 30‐day period following placement were recorded. Overall, there were 134 transient ischemic attacks (TIAs) for a rate of 2.82%. Based on the total patient population, there were 129 minor strokes with a rate of occurrence of 2.72%. The total number of major strokes was 71 for a rate of 1.49%. There were 41 deaths within a 30‐day postprocedure period resulting in a mortality rate of 0.86%. The combined minor and major strokes and procedure‐related death rate was 5.07%. Restenosis rates of carotid stenting have been 1.99% and 3.46% at 6 and 12 months, respectively. The rate of neurologic events after stent placement has been 1.42% at 6–12‐month follow‐up. Endovascular stent treatment of carotid artery atherosclerotic disease is growing as an alternative for vascular surgery, especially for patients that are high risk for standard carotid endarterectomy. The periprocedure risks for major and minor strokes and death are generally acceptable at this early stage of development and have not changed significantly since the first survey results. Cathet. Cardiovasc. Intervent. 50:160–167, 2000. ©2000 Wiley–Liss,Inc.

Updated review of the global carotid artery stent registry

The purpose of this article was to review and update the current status of carotid artery stent placement in the world. Surveys of major interventional centers in Europe, North and South America, and Asia were initially completed in June 1997. Subsequent updates from these 24 centers in addition to 29 new centers have been obtained to bring up to date the information. The survey asked the various questions regarding the patients enrolled, procedure techniques, and results of carotid stenting, including complications and restenosis. The total number of endovascular carotid stent procedures that have been performed worldwide to date included 12,392 procedures involving 11,243 patients. There was a technical success of 98.9% with 12,254 carotid arteries treated. Complications that occurred during the carotid stent placement or within a 30‐day period following placement were recorded. Overall, there was transient ischemic attack rate of 3.07%, minor strokes of 2.14%, major strokes of 1.20%, and procedure‐related deaths of 0.64%. The combined minor and major strokes and procedure‐related death rate was 3.98% based on procedure number. With nonprocedure‐related death rate of 0.77%, the total stroke and death rate was 4.75%. Subsets of questions were directed at the new use of distal embolic protection devices; there were 6,753 cases done without protection and which incurred a 5.29% rate of strokes and procedure‐related deaths. In the 4,221 cases with cerebral protection, there was a 2.23% rate of strokes and procedure‐related deaths. Restenosis rates of carotid stenting have been 2.7%, 2.6%, and 2.4% at 1, 2, and 3 years, respectively. The rate of neurologic events after stent placement has been 1.2%, 1.3%, and 1.7% at 1, 2, and 3 years, respectively. Endovascular stent treatment of carotid artery atherosclerotic disease is growing as an alternative for vascular surgery, especially for patients who are high risk for standard carotid endarterectomy. The periprocedure risks for major and minor strokes and death are generally acceptable at this early stage of development and have shown an improvement with technological developments, including distal embolic protection. Catheter Cardiovasc Interv 2003;60:259‐266

Current global status of carotid artery stent placement.

Our purpose was to review the current status of carotid artery stent placement throughout the world. Surveys were sent to major interventional centers in Europe, North and South America, and Asia. Information from peer-reviewed journals was also included and supplemented the survey. The survey asked various questions regarding the patients enrolled, procedure techniques, and results of carotid stenting, including complications and restenosis. Of the centers which were sent surveys, 24 responded. The total number of endovascular carotid stent procedures that have been performed worldwide to date included 2,048 cases, with a technical success of 98.6%. Complications that occurred during carotid stent placement or within a 30-day period following placement were recorded. Overall, there were 63 minor strokes, with a rate of occurrence of 3.08%. The total number of major strokes was 27, for a rate of 1.32%. There were 28 deaths within a 30-day postprocedure period, resulting in a mortality rate of 1.37%. Restenosis rates of carotid stenting have been 4.80% at 6 mo. Endovascular stent treatment of carotid artery atherosclerotic disease is growing as an alternative to vascular surgery, especially for patients that are at high risk for standard carotid endarterectomy. The periprocedural risks for major and minor strokes and death are generally acceptable at this early stage of development.

Endovascular Stents for Carotid Artery Occlusive Disease

Purpose: To study the feasibility and safety of endovascular stenting of cervical carotid artery stenosis. Methods: Between April 1994 and May 1997, 108 consecutive patients (58 men; mean age 70.1 years) with ≥ 70% carotid stenosis were treated with percutaneous stent implantation under a protocol that featured independent neurological review. Forty-four percent were asymptomatic. Over half the lesions (59%) were in the internal carotid artery; the mean stenosis was 86%. Palmaz stents were implanted without cerebral protection following preliminary balloon dilation; two Wallstents were used in long lesions. Results: Carotid stents were successfully placed in 108 of 114 (95%) lesions. Of the 6 technical failures, 5 were access related and 1 was due to seizures during balloon dilation. Two major (1.8%) and 2 minor (1.8%) strokes occurred (3.7% stroke rate for 108 patients; 3.5% in 114 procedures), all in symptomatic patients, one of whom died. There were 5 (4.4%) transient ischemic attacks and 2 (1.8%) brief seizure episodes during dilation. One patient died of a cardiac event on day 20. The all stroke or death rate was 5.3% based on 114 arteries at risk (5.6% in 108 patients). In the mean 6-month follow-up (range 1 to 36) of 97 eligible patients, 3 (3.1%) died from unrelated causes. There was 1 restenosis (1.0%) from a stent compression, which was successfully redilated. There were no neurological sequelae, cranial palsies, or cases of stent or vessel thrombosis in follow-up. Conclusions: The use of stents in the treatment of cervical carotid occlusive disease appears feasible, effective in the short term, and without excessive risk of periprocedural stroke.

Distal Embolic Protection During Femoropopliteal Atherectomy

We report on a series of 10 consecutive cases of superficial femoral and popliteal artery atherectomy with the SilverHawk device, carried out for the treatment of peripheral vascular atherosclerosis. All cases were done with the use of a distal embolic protection device. Debris were retrieved in the filter in each case. Implications are discussed, along with a review of the available literature on this device.

Initial Clinical Experience with Colonic Stent Placement

BACKGROUND The purpose of this study is to review initial experience with a colonic stent as an alternative to colostomy in patients with colonic obstruction. METHODS Ten patients diagnosed with acute colonic obstructions from both benign and malignant causes underwent stent placement. Self-expandable metallic stents were deployed using fluoroscopic guidance. Patients were followed up clinically until removal of the stent or death. RESULTS Nine of the 10 patients who underwent colonic stent placement achieved clinical decompression within 6 hours. Six patients underwent standard mechanical bowel preparation and elective resection of obstructing lesions. The other 4 patients received stent placement for palliative purposes. Complications included 4 cases of migration and 1 death. Migrated stents in the rectum were easily retrieved and replaced using fluoroscopic techniques. There were no perforations. CONCLUSION Placement of self-expandable metallic stents for acute colonic obstructions may allow patients to undergo elective surgical resection avoiding possible colostomy.

Comparison of thrombolytic therapy of lower-extremity acute, subacute, and chronic arterial occlusions

Our purpose was to study the effectiveness of thrombolytic therapy in treating acute, subacute, and chronic arterial occlusions in a multicenter retrospective study. Intraarterial urokinase infusion was performed in 235 patients for occluded native arteries. There were 70 (30%) with acute and 26 (5%) with subacute occlusions, and 141 (59%) with chronic symptoms for longer than 3 mo. Complete thrombolysis was achieved in 60 (86%) of the acute, 20 (77%) of the subacute, and 106 (75%) of the chronic occlusions. Adjunctive interventional procedures were performed as needed. Long-term follow-up revealed a primary patency of 87%, 85%, and 76% for the acute, subacute, and chronic occlusion groups, respectively. We conclude that the rate of complete thrombolysis of chronic occlusions proved slightly more efficient for acute and virtually the same for subacute occlusions. Long-term follow-up demonstrated a higher failure rate with chronic than with acute occlusions, probably due to worsened peripheral vascular runoff.

Management of Neurological Complications of Carotid Artery Stenting

PURPOSE To review the neurological complications associated with extracranial carotid artery stenting and to preliminarily assess techniques used to manage these complications. METHODS Between April 1994 and August 2000, 450 patients (270 men; mean age 70.2 years, range 27-89) had stents implanted to treat 472 cervical carotid artery stenoses. Over half (257, 57%) of the patients were symptomatic. A variety of stents were implanted percutaneously after predilation of the lesion; a third of the patients received glycoprotein IIb/ IIIa inhibitors intraprocedurally in addition to a standard oral antiplatelet regimen (aspirin and ticlopidine or clopidogrel). Occurrence and management of neurological complications within the 30-day periprocedural period were reviewed. RESULTS There were 14 (3.1%) transient ischemic attacks (TIAs), 10 (2.2%) minor strokes, and 3 (0.7%) major strokes. Among 6 (1.3%) procedure-related deaths, 4 had neurological causes. The total stroke and death rate was 4.2% (n = 19). All the TIAs, 4 of which occurred between 1 and 14 days poststenting, were treated medically, as were the minor strokes, 3 of which occurred >24 hours after stenting. Only 2 minor stroke patients had mild residual upper extremity motor deficits. Intra-arterial thrombolytic therapy was administered in 5 cases (2 major strokes survivors and 3 patients who suffered a neurologically-related death); occlusions were identified in the proximal middle cerebral artery (MCA) in 3 and the distal MCA in 2. Angiographic improvement was noted in 4 (80%), but only the 2 (40%) with distal MCA occlusions did well clinically. CONCLUSIONS Neurological complications following carotid artery stenting are inevitable. The occurrence of minor strokes >24 hours following stenting may indicate a possible late embolic phenomenon, which warrants investigation. Likewise, the marginal efficacy of intra-arterial thrombolytic therapy demonstrates an inability to lyse embolic plaque and underscores the need for effective distal protection.

Evaluation of Glycoprotein IIb/IIIa Inhibitors in Carotid Angioplasty and Stenting

PURPOSE To review the immediate neurological and bleeding complications associated with the use of glycoprotein (GP) IIb/IIIa inhibitors in patients undergoing extracranial carotid artery stent placement. METHODS A retrospective review was performed of 550 patients (321 men; mean age 71.1 years, range 28-91) who underwent carotid artery angioplasty and stent placement. Glycoprotein IIb/IIIa inhibitors were given prophylactically along with heparin to 216 patients, whose outcomes were compared to a control group of 334 patients who received intravenous heparin alone. Primary endpoints were the immediate and 30-day neurological complications, including transient ischemic attacks (TIAs), minor and major strokes, and neurologically-related deaths. The secondary endpoint was any abnormal bleeding. RESULTS The all stroke/neurological death rate in 216 patients treated with heparin and GP IIb/IIIa inhibitors was 6.0% (13 events) compared 2.4% (8 events) in the 334 patients in the heparin-only control group (p=0.0430). Two of the 4 neurologically-related deaths in the GP IIb/IIIa inhibitor group resulted from intracranial hemorrhages; there were no intracranial hemorrhages in the heparin-only group. There was 1 episode of extracranial bleeding in the GP IIb/IIIa inhibitor group treated with embolization. The incidences of significant puncture-site bleeding requiring transfusion were similar in the groups. CONCLUSIONS Neurological complications following percutaneous carotid artery interventions have been relatively few. The neurological sequelae in carotid stent patients receiving glycoprotein IIb/IIIa inhibitors were more numerous and consequential, which suggests that the use of GP IIb/IIIa inhibitors in carotid stenting should be discouraged.

Wall apposition assessment and performance comparison of distal protection filters

Purpose: To assess the wall apposition of 3 distal protection filters used in carotid artery stenting (CAS) for cerebral protection and quantify the effect on the in vitro capture efficiency of the filters under simulated physiological flow conditions. Methods: The 3 distal protection filters (Angioguard XP, FilterWire EZ, and RX Accunet) were deployed in silicone flow models of 5.0-, 5.5-, and 6.0-mm inner diameter and were tested at a mean flow rate characteristic of the human internal carotid artery while injecting polydispersed microspheres simulating plaque emboli. The injected microspheres had a diameter larger than the pore size of the devices tested, so it was conjectured that any microspheres missed by the device traveled between the device basket and the vessel wall. Varying the diameter of the vessel phantom within the recommended vessel diameter treatment range for each device simulated the variability of vessel diameter in vivo, allowing the quantification of device wall apposition. Results: None of the devices tested completely prevented distal embolization in the flow model. The RX Accunet device has the best overall wall apposition, yielding gaps of 0.075% of the vessel cross-sectional area. The FilterWire EZ device had the best overall average filtration rate, failing to capture only 0.8% of plaque particles. There were no statistically significant differences in the wall apposition assessment or the capture efficiency of the RX Accunet and FilterWire EZ devices. Conclusion: Several complications related to apposition of the filter basket on the vessel wall and device retrieval were detected in all the devices. It is inferred that the adaptability of the filter basket to conform to the vessel cross section at the site of deployment is the primary design variable responsible for distal embolization during CAS with cerebral protection.