Mechanical thromboembolectomy for acute ischemic stroke: comparison of the catch thrombectomy device and the Merci Retriever in vivo

BACKGROUND AND PURPOSE: The purpose of the study was to compare efficacy and potential complications of 2 commercially available devices for mechanical thromboembolectomy. METHODS: Devices were tested in an established animal model allowing the use of routine angiography catheters and thrombectomy devices. Radio-opaque thrombi were used for visualization of thrombus-device interaction during angiography. The Merci Retrieval System and the Catch Thromboembolectomy System were assessed each in 10 vessel occlusions. For every occluded vessel up to 5 retrieval attempts were performed. RESULTS: Sufficient recanalization was achieved with the Merci Retriever in 90% of occlusions, and with the Catch device recanalization was achieved in 70% of occlusions. Recanalization at the first attempt occurred significantly more often with the Merci Retriever compared to the Catch device (OR, 21; 95% CI, 1.78-248.11). Consequently, significantly more attempts (P=0.02) had to be performed with the Catch device; therefore, time to recanalization was longer. Thrombus fragmentations during retrieval were caused more often by the Catch device compared to the Merci Retriever (OR, 15.6; 95% CI, 1.73-140.84), resulting in a higher distal embolization rate. During retrieval both devices lost thrombotic material at the tip of the guide catheter, which was then aspirated in most cases. CONCLUSIONS: Both distal devices are effective for thromboembolectomy. To avoid loss of thrombotic material and distal embolization, the use of large luminal balloon guide catheters and aspiration during retrieval seems to be mandatory. The design of the Merci Retriever appears to be more efficient during thrombus mobilization and retrieval with less fragmentation compared to the Catch Thromboembolectomy System.

Occlusion length is a crucial determinant of efficiency and complication rate in thrombectomy for acute ischemic stroke

BACKGROUND AND PURPOSE: Although mechanical thrombectomy (MT) has an encouragingly high recanalization rate in treating stroke, it is associated with severe complications of which the underlying factors have yet to be identified. Because MT is a mechanical approach, the mechanical properties of the thrombus might be crucial for its success. The present study assesses the effect of thrombus length on the in vivo effectiveness and complication rate of MT. MATERIALS AND METHODS: Angiography and embolization of 21 cranial vessels with radiopaque whole-blood thrombi 10, 20, and 40 mm in length (7 occlusions each) were performed in 7 swine. MT was carried out using a distal snarelike device (BCR Roadsaver) with proximal balloon occlusion. A total of 61 retrievals were attempted. RESULTS: In the group of 10-mm occlusions, 77.8% of the attempts achieved complete recanalisation. For longer occlusions, the success rates decreased significantly to 20% of attempts for 20-mm occlusions (odds ratio [OR], 14; 95% confidence interval [CI], 2.2-89.2) and 11.1% for 40-mm occlusions (OR, 28; 95% CI, 3.9-202.2; P < .005). The low success rates were largely due to complications associated with thrombus compaction during retrieval. Similarly, the rate of thromboembolic events increased from 0% in 10-mm occlusions to 14.8% in 40-mm occlusions. CONCLUSIONS: MT using a distal device proved to be a fast, effective, and safe procedure for recanalizing short (10-mm) occlusions in the animal model. However, occlusion length emerged as a crucial determinant for MT with a significant decrease in recanalization success per attempt and increased complication rates. These findings suggest limitations of MT in the clinical application.

Endovascular and surgical treatment of spinal dural arteriovenous fistulas

INTRODUCTION: The aim of this retrospective study was to evaluate the clinical outcome of patients with spinal dural arteriovenous fistulas (SDAVFs) that were treated with surgery, catheter embolization, or surgery after incomplete embolization. METHODS: The study included 21 consecutive patients with SDAVFs of the thoracic, lumbar, or sacral spine who were treated in our institution from 1994 to 2007. Thirteen patients were treated with catheter embolization alone. Four patients underwent hemilaminectomy and intradural interruption of the fistula. Four patients were treated by endovascular techniques followed by surgery. The clinical outcome was assessed using the modified Aminoff-Logue scale (ALS) for myelopathy and the modified Rankin scale (MRS) for general quality of life. Patient age ranged from 44 to 77 years (mean 64.7 years). RESULTS: Surgical as well as endovascular treatment resulted in a significant improvement in ALS (-62.5% and -31.4%, respectively, p < 0.05) and a tendency toward improved MRS (-50% and -32%, respectively) scores. Patients that underwent surgery after endovascular treatment due to incomplete occlusion of the fistula showed only a tendency for improvement in the ALS score (-16.7%), whereas the MRS score was not affected. CONCLUSION: We conclude that both endovascular and surgical treatment of SDAVFs resulted in a good and lasting clinical outcome in the majority of cases. In specific situations, when a secondary neurosurgical approach was required after endovascular treatment to achieve complete occlusion of the SDAVF, the clinical outcome was rather poor. The best first line treatment modality for each individual patient should be determined by an interdisciplinary team.

Orbital venous malformation: percutaneous treatment using an electrolytically detachable fibred coil

PURPOSE: To report the efficacy of percutaneous treatment of an orbital venous malformation with an electrolytically detachable fibred coil. METHODS: We report an instance of radiography-guided percutaneous treatment with an electrolytically detachable fibred coil in a 16-year-old boy with acute, spontaneous, painless proptosis on the left side, which progressed with time. RESULTS: Magnetic resonance imaging, angiography and orbitophlebography revealed a low-flow, intraorbital venous malformation. Percutaneous puncture and drainage were followed by a short remission. Following an acute recurrence, a single detachable fibred coil was deployed via a percutaneous approach under angiographic guidance. No radiological or clinical recurrences were observed over 4 years. CONCLUSIONS: Embolization of a deep orbital venous malformation with detachable fibred coils via a percutaneous approach can be highly effective, and may be considered before proceeding with open surgery.

Stent-grafts in the treatment of emergent or urgent carotid artery disease: review of 25 cases

PURPOSE: To report the authors' initial experience with carotid artery stent-grafts in a comparatively large patient series for the treatment of acute bleeding and impending rupture or the prevention of distal embolization. MATERIALS AND METHODS: This retrospective study was approved by the institutional review boards and performed according to HIPPA standards. Twenty-five patients were treated with 27 carotid artery stent-grafts (Gore Viabahn, n = 10; Bard Fluency, n = 9; polytetrafluoroethylene-covered Palmaz, n = 5; and Wallgraft, n = 3). Thirteen stent-grafts were placed in patients with carotid blow-out syndrome (including three patients with carotid-airway fistula), 12 in patients with either pseudoaneurysm (n = 9) or true aneurysm (n = 3), and two in patients with intractable high-grade bare stent restenosis. RESULTS: The technical success rate was 100% (27 of 27 cases). No acute procedural transient ischemic attacks or strokes occurred. Procedural dissections occurred in two of the 27 cases (7.4%). Short-term complications occurred in three of the 27 cases (11%) (repeat hemorrhage, n = 2; common carotid artery occlusion, n = 1). The overall patient mortality rate was 36% (nine of 25 patients, all with carotid blow-out syndrome). Six-month follow-up in 15 of the 16 living patients demonstrated widely patent stent-grafts. Two patients with pseudoaneurysm also demonstrated patent stents at 18- and 33-month follow-up. CONCLUSIONS: Stent-grafts may be useful in the treatment of carotid artery bleeding syndrome, aneurysm, and stenosis, with a high procedural success rate in selected cases. The results of mid-term follow-up are encouraging, but results of long-term follow-up must be evaluated in future studies.

[Diagnosis and treatment of carotid cavernous fistulas]

This article provides an overview on the actual state of the interventional neuroradiological management of carotid cavernous fistulas depending on their anatomy and pathophysiology. The results are based on our experience gained during the treatment of patients with complex CCF during the last 15 years. Indications, procedures, and results of transarterial, transvenous and combined arteriovenous approaches for balloon occlusion, embolization, coiling and stenting of these lesions are discussed. Progress in this field is constant so that new technical advances are expected to improve the safety and to expand the indications for these procedures in the future.

Single center experience with provisional abciximab therapy in complex lower limb interventions

BACKGROUND: Abciximab, a glycoprotein IIb/IIIa antagonist has been shown to improve patency and clinical outcome in patients undergoing endovascular recanalization of femoro-popliteal occlusions. However, data on abciximab therapy in complex peripheral catheter interventions of lower limbs are quite limited. The objective of this retrospective study was to evaluate the clinical and hemodynamic outcomes of patients treated with provisional abciximab during complex peripheral catheter interventions. PATIENTS AND METHODS: Analysis of a consecutive series of 44 patients with provisional abciximab therapy in complex peripheral catheter interventions with imminent risk of early rethrombosis defined as revascularization of arterial occlusions associated with one or more of the following additional circumstances named as time-consuming intervention > 3 hours, compromised contrast flow not solved by stenting, distal embolization not solved by mechanical thromboembolectomy, and peri-interventional notice of thrombus evolution despite adequate heparin adjustment of lower limbs. Adjunctive abciximab therapy was started in accordance to percutaneous coronary bailout situations. The decision to add abciximab was based on the decision of the operator and went along with the judgement that there is a rising risk of reocclusion due to the progressive complexity of an individual intervention. A bolus of 0.25 mg per kilogram of body weight, followed by a maintenance infusion of 0.125 microg/kg/min (up to a maximum dosage of 10 microg/min) for 12 hours was administered. Clinical and hemodynamic outcome was prospectively assessed at discharge, three and six months after the index procedure. RESULTS: The occluded artery of 44 limbs was in the iliac (2%), in the femoro-popliteal (73%) or below the knee segment (25%). Overall, occlusion length was 11.5 +/- 6.5 cm. Technical success rate was 95%. Mean ABI increased from 0.5 +/- 0.16 to 0.88 +/- 0.19 (p < 0.001) with immediate hemodynamic improvement of 91%. Overall, sustained clinical improvement was 84% and 66% at three and six months follow-up, with best results in iliac (100%), followed by below the knee (73%) and by femoro-popliteal segment (63%) at six months, respectively. Overall, secondary clinical improvement was 86% at six months. Minor and major bleeding complications were 16% and 9%, respectively. CONCLUSION: Abciximab should be noticed as medical adjunct in the interventional armamentarium to prevent imminent rethrombosis in complex peripheral catheter interventions.

Vascular birthmarks

Vascular birthmarks can be classified into hemangioma and vascular malformations. Hemangioma are frequent tumours of early infancy demonstrating endothelial hyperplasia, a history of rapid neonatal growth and slow involution during later childhood. Treatment of hemangioma is dependent of stage and type of the lesion. Given the current availability of drugs, lasers, and other techniques to treat hemangioma safely, philosophy of "benign neglect" should not be considered anymore. Vascular malformations show a normal endothelial turnover, being present at birth and growing commensurately with the child. Exact diagnosis by employing modern diagnostic means,which are able to differentiate low-flow from high flow lesions is important for further therapeutic management. Beside conservative treatment strategies, use of laser, sclerotherapy, interventional embolization and surgical treatment are possible management options. Patients should receive multidisciplinary care in qualified vascular centres.

Percutaneous closure of patent foramen ovale for migraine headaches refractory to medical treatment

BACKGROUND: Patent foramen ovale (PFO) has been linked to migraine, and several retrospective studies reported an improvement in migraine prevalence or frequency after PFO closure for other reasons, mostly for secondary prevention of paradoxical embolism or following diving accidents. We investigated the outcome of patients undergoing PFO closure solely for migraine headaches refractory to medical treatment. METHODS: Seventeen patients (age 44 +/- 12 years; 76% female; one atrial septal aneurysm) underwent percutaneous PFO closure using the Amplatzer PFO Occluder (AGA Medical Corporation, Golden Valley, MN). An 18-mm device was used in two patients, a 25-mm device in 13, and a 35-mm device in two. The interventions were solely guided by fluoroscopy, without intraprocedural echocardiography. RESULTS: All implantation procedures were successful. There were no peri-procedural complications. Contrast transesophageal echocardiography after Valsalva maneuver at 6 months showed complete PFO closure in 16 patients (94%), whereas a minimal residual shunt persisted in one (6%). During 2.7 +/- 1.5 years of follow-up, no deaths and no embolic events occurred. After PFO closure, migraine headaches disappeared in four patients (24%), and improved in eight additional patients (47%). Three patients (18%) reported a decrease of their headaches by 75%, three patients (18%) a decrease of 50%, and two patients (12%) a decrease of 25%, while headaches remained unchanged in five patients (29%). No patient experienced worsening headaches. Moreover, the prevalence of migraine with aura decreased from 82 to 24% (P = 0.002). CONCLUSIONS: These results suggest that percutaneous PFO closure durably alters the spontaneous course of shunt associated migraine.

Sex differences in cryptogenic stroke with patent foramen ovale

BACKGROUND: Sex differences in patients with patent foramen ovale (PFO) and cryptogenic stroke have not been systematically analyzed. We aimed to determine sex influences on demographics, vascular risk factors, clinical manifestations, stroke location, and clinical outcome. METHODS: One thousand two hundred eighty-eight consecutive patients with ischemic stroke or transient ischemic attack (TIA) were admitted to a single stroke center. All patients underwent a complete stroke workup including clinical examination, standard blood tests, cerebral and vascular imaging, transesophageal echocardiography, and 24-hour electrocardiography. In 500 patients, no definite etiology could be established (cryptogenic stroke/TIA). Of them, 167 patients (107 men and 60 women, mean age 52 +/- 13 years) had an PFO. RESULTS: The prevalence of PFO in patients with cryptogenic stroke or TIA was higher in men than in women (38% vs 28%, P = .014). Stroke severity and the prevalence of risk factors did not differ between the 2 sexes. There was an independent association between male sex and stroke location in the posterior cerebral circulation (OR 3.0, 95% CI 1.4-6.5, P = .006). Men and women did not differ in respect to PFO grade, prevalence of right-to-left shunt at rest, or coexistence of atrial septal aneurysm. Clinical outcome at 3 months was similar in both sexes. CONCLUSION: Patent foramen ovale was more prevalent in men than in women with cryptogenic stroke. There were no sex influences on age, risk factors, echocardiographic characteristics of PFO, or clinical outcome. Male sex was independently associated with stroke in the posterior cerebral circulation.

Device-less patent foramen ovale closure by radiofrequency thermal energy

The goal of this study was to assess the feasibility, safety and success of a system which uses radiofrequency energy (RFE) rather than a device for percutaneous closure of patent foramen ovale (PFO). METHODS: Sixteen patients (10 men, 6 women, mean age 50 years) were included in the study. All of them had a proven PFO with documented right-to-left shunt (RLS) after Valsalva manoeuvre (VM) during transoesophageal echocardiography (TEE). The patients had an average PFO diameter of 6 +/- 2 mm at TEE and an average of 23 +/- 4 microembolic signals (MES) in power M-mode transcranial Doppler sonography (pm-TCD), measured over the middle cerebral artery. An atrial septal aneurysm (ASA) was present in 7 patients (44%). Balloon measurement, performed in all patients, revealed a stretched PFO diameter of 8 +/- 3 mm. In 2 patients (stretched diameter 11 and 14 mm respectively, both with ASA >10 mm), radiofrequency was not applied (PFO too large) and the PFO was closed with an Amplatzer PFO occluder instead. A 6-month follow-up TEE was performed in all patients. RESULTS: There were no serious adverse events during the procedure or at follow-up (12 months average). TEE 6 months after the first RFE procedure showed complete closure of the PFO in 50% of the patients (7/14). Closure appeared to be influenced by PFO diameter, complete closure being achieved in 89% (7/8) with a balloon-stretched diameter < or =7 mm but in none of the patients >7 mm. Only one of the complete closure patients had an ASA. Of the remainder, 4 (29%) had an ASA. Although the PFO was not completely closed in this group, some reduction in the diameter of the PFO and in MES was documented by TEE and pm-TCD with VM. Five of the 7 residual shunt patients received an Amplatzer PFO occluder. Except for one patient with a minimal residual shunt, all showed complete closure of PFO at 6-month follow-up TEE and pm-TCD with VM. The other two refused a closure device. CONCLUSIONS: The results confirm that radiofrequency closure of the PFO is safe albeit less efficacious and more complex than device closure. The technique in its current state should not be attempted in patients with a balloon-stretched PFO diameter >7 mm and an ASA.

The effect of pulsed jet lavage in vertebroplasty on injection forces of polymethylmethacrylate bone cement, material distribution, and potential fat embolism: a cadaver study

STUDY DESIGN: In vitro testing of vertebroplasty techniques including pulsed jet-lavage for fat and marrow removal in human cadaveric lumbar and thoracic vertebrae. OBJECTIVE: To develop jet-lavage techniques for vertebroplasty and investigate their effect on cement distribution, injection forces, and fat embolism. SUMMARY OF BACKGROUND DATA: The main complications of cement vertebroplasty are cement leakage and pulmonary fat embolism, which can have fatal consequences and are difficult to prevent reliably by current vertebroplasty techniques. METHODS: Twenty-four vertebrae (Th8-L04) from 5 osteoporotic cadaver spines were grouped in triplets depending on bone mineral density (BMD). Before polymethylmethacrylate (PMMA) vertebroplasty, a pulsatile jet-lavage for removal of intertrabecular fat and bone marrow was performed in 2 groups with 8 specimens each, performing radial and axial irrigation from the biopsy needles. One hundred mL of Ringer solution were injected through 1 pedicle and regained by low vacuum via the contralateral pedicle. Eight control vertebrae were not irrigated. All specimens underwent standardized PMMA cement augmentation injecting 20% of the vertebral volume. Injection forces, cement distribution, and extravasations were quantified. RESULTS: All irrigation solution could be retrieved with the vacuum applied. A Kruskal-Wallis test revealed significantly higher injection forces of the control group as compared with the irrigated groups (P = 0.021). Dilatation of the syringe at forces above 300 N occurred in 75% of the untreated compared with 12.5% of the lavaged specimens. CT distribution analysis showed more homogenous cement distribution of the cement and significantly less extravasation in the irrigated specimens. CONCLUSION: The developed lavage technique for vertebroplasty showed to be feasible and reproducible. The reduction of injection forces would allow the use of more viscous PMMA cement lowering the risk for cement embolization and results in a safer procedure. The wash-out of bone marrow and the possible reduction of pulmonary fat embolism have to be verified with in vivo models.

Interventional management of hypervascular osseous metastasis: role of embolotherapy before orthopedic tumor resection and bone stabilization

OBJECTIVE: The purpose of this study was to evaluate, in relation to intraoperative estimated blood loss (EBL), the effectiveness of preoperative transcatheter arterial embolization of hypervascular osseous metastatic lesions before orthopedic resection and stabilization. MATERIALS AND METHODS: Between June 1987 and November 2007, 22 patients underwent transcatheter arterial embolization of tumors of the long bone, hip, or vertebrae before resection and stabilization. Osseous metastatic lesions from renal cell carcinoma, malignant melanoma, leiomyosarcoma, and prostate cancer were embolized. All patients were treated with a coaxial catheter technique with polyvinyl alcohol (PVA) particles alone or a combination of PVA particles and coils. After embolization, each tumor was angiographically graded according to devascularization (grades 1-3) based on tumor blush after contrast injection into the main tumor-feeding arteries. RESULTS: In patients with complete devascularization (grade 1), mean EBL was calculated to be 1,119 mL, whereas in patients with partial embolization (grades 2 and 3) EBL was 1,788 mL and 2,500 mL. With respect to intraoperative EBL, no significant difference between devascularization grades was found (p > 0.05). Moderate correlation (r = 0.51, p = 0.019) was observed between intraoperative EBL and tumor size before embolization. Only low correlation (r = 0.44, p = 0.046) was found between intraoperative EBL and operating time. Major complications included transient palsy of the sciatic nerve and gluteal abscess in one patient. CONCLUSION: The results of this study support the concept that there is no statistically significant difference among amounts of intraoperative EBL with varying degrees of embolization.

Diagnosis and treatment of peripartum bleeding

Severe peripartum hemorrhage (PPH) contributes to maternal morbidity and mortality and is one of the most frequent emergencies in obstetrics, occurring at a prevalence of 0.5-5.0%. Detection of antepartum risk factors is essential in order to implement preventive measures. Proper training of obstetric staff and publication of recommendations and guidelines can effectively reduce the frequency of PPH and its resulting morbidity and mortality. Therefore, an interdisciplinary expert committee was formed, with members from Germany, Austria, and Switzerland, to summarize recent scientific findings. An up-to-date presentation of the importance of embolization and of the diagnosis of coagulopathy in PPH is provided. Furthermore, the committee recommends changes in the management of PPH including new surgical options and the off-label use of recombinant factor VIIa.

DISTRIBUTED APPROACH FOR SOLVING OPTIMAL POWER FLOW PROBLEMS IN THREE-PHASE UNBALANCED DISTRIBUTION NETWORK

The objective of this report is to study distributed (decentralized) three phase optimal power flow (OPF) problem in unbalanced power distribution networks. A full three phase representation of the distribution networks is considered to account for the highly unbalance state of the distribution networks. All distribution network’s series/shunt components, and load types/combinations had been modeled on commercial version of General Algebraic Modeling System (GAMS), the high-level modeling system for mathematical programming and optimization. The OPF problem has been successfully implemented and solved in a centralized approach and distributed approach, where the objective is to minimize the active power losses in the entire system. The study was implemented on the IEEE-37 Node Test Feeder. A detailed discussion of all problem sides and aspects starting from the basics has been provided in this study. Full simulation results have been provided at the end of the report.