Hopkins Ln

Prevention and treatment of thromboembolic and ischemic complications associated with endovascular procedures: Part I--Pathophysiological and pharmacological features.

Thromboembolic and ischemic complications frequently occur during and after endovascular procedures, because of associated arterial injury and the thrombogenic characteristics of arterial catheters, contrast agents, and implanted devices such as coils and stents. Platelet adhesion, activation, and aggregation occurring at the site of arterial injury are mediated by local factors, including thromboxane A2 (inhibited by aspirin) and adenosine diphosphate (inhibited by ticlopidine and clopidogrel). Concomitantly, thrombin is formed by serial activation of clotting factors via contact with subendothelial tissue factor. Thrombin cleaves fibrinogen into fibrin. Thrombin activation is indirectly blocked by heparin and its analogs. However, after thrombin is clot-bound (with fibrin), it is relatively protected from heparin and is effectively blocked only by direct thrombin inhibitors (hirudin and its analogs). The final common pathway in clot formation is the binding of fibrinogen to platelets via platelet glycoprotein IIb/IIIa receptors, which is inhibited by antibodies to platelet IIb/IIIa receptors. New treatment modalities, such as the use of direct thrombin inhibitors and antibodies to platelet glycoprotein IIb/IIIa, seem to be more effective for prophylaxis and treatment than conventional anticoagulation and antiplatelet therapies.

Temporary balloon protection as an adjunct to endosaccular coiling of wide-necked cerebral aneurysms: technical note.

OBJECTIVEnWe present an endovascular technique for treating wide-necked cerebral aneurysms using Guglielmi detachable coils (Target Therapeutics, Fremont, CA) and simultaneous temporary balloon protection. The temporary balloon serves as a mechanical external force to mold the microcoils away from the parent artery.nnnMETHODSnTwo illustrative cases of wide-necked cerebral aneurysms treated with Guglielmi detachable coils and a temporary balloon are presented. Emphasis is placed on the technical aspects of the approach, with several variations. The first case involves a left posterior cerebral artery aneurysm at the P1/P2 segment, and the second case involves a left paraclinoid internal carotid artery aneurysm. Both patients suffered from subarachnoid hemorrhage, but neither was a candidate for craniotomy. In each case, the coils, when used alone, protruded into the parent artery and were therefore removed. Then a temporary balloon was inflated for mechanical protection during coil deployment.nnnRESULTSnThe use of simultaneous temporary balloon protection allowed more dense intra-aneurysmal coil packing, especially in the neck, without parent artery compromise, than did the use of Guglielmi detachable coils alone.nnnCONCLUSIONnEndovascular treatment of wide-necked cerebral aneurysms can be facilitated by simultaneous temporary balloon protection.

Complications after treatment with pipeline embolization for giant distal intracranial aneurysms with or without coil embolization.

BACKGROUND AND IMPORTANCEnThe Pipeline Embolization Device (PED) is a flow diverter designed to treat intracranial aneurysms through endoluminal parent vessel reconstruction. The role of adjunctive coil embolization is unknown.nnnCLINICAL PRESENTATIONnThis report details the authors experience with the PED in 2 patients with symptomatic, giant distal intracranial aneurysms (1 basilar artery and 1 M1 segment middle cerebral artery). Both patients had successful parent vessel reconstruction. In the first patient, the basilar artery aneurysm was treated with PEDs alone, and the patient experienced early fatal brainstem hemorrhage from aneurysm rupture. In the second patient, the M1 aneurysm was treated with 2 PEDs along with dense coil embolization, with a good initial angiographic result. This patient experienced acute thrombosis of the PED post-procedure, likely related to mass effect and thrombogenicity of the dense coil mass.nnnCONCLUSIONnFlow diversion is an evolutionary step in the treatment of giant intracranial aneurysms. However, complete aneurysm occlusion occurs over a delayed period. The authors recommend placement of coils in addition to PED in the treatment of large or giant distal intracranial aneurysms in an attempt to protect the dome. However, robust packing is to be avoided because it can lead to acute PED thrombotic or compressive occlusion.

Prognostic value and determinants of ultraearly angiographic vasospasm after aneurysmal subarachnoid hemorrhage.

OBJECTIVEnA small number of patients with aneurysmal subarachnoid hemorrhage have angiographic evidence of cerebral vasospasm within 48 hours of the onset of hemorrhage. The present study analyzes the prognostic value and determinants of this ultraearly angiographic finding.nnnMETHODSnWe analyzed prospectively collected data from the placebo-treated group in a multicenter clinical trial conducted at 54 neurosurgical centers in North America. The presence and severity of ultraearly angiographic vasospasm (UEAV) was determined by a blinded review of the admission angiograms. Using logistic regression analysis, we identified independent determinants of UEAV from demographic, clinical, laboratory, and neuroimaging characteristics of the patients. The impact of UEAV on the risk of symptomatic vasospasm and 3-month outcome was analyzed after adjusting for potential confounding factors.nnnRESULTSnOf 296 patients in the analysis, 37 (13%) had angiographic evidence of vasospasm at admission. An initial Glasgow Coma Scale score of less than 14 (odds ratio [OR], 2.5; 95% confidence interval [CI], 1.1-6.0), and serum sodium greater than 138 mmol/L (OR, 3.4; 95% CI, 1.5-8.3) were associated with UEAV. UEAV was associated with increased risk of symptomatic vasospasm (OR, 2.5; 95% CI, 1.2-5.4) and poor outcome at 3 months (OR, 2.8; 95% CI, 1.2-6.3), after adjusting for other variables. This risk of symptomatic vasospasm was not influenced by early surgery (within 48 h of hemorrhage onset). Poor outcome was more likely to occur in patients with UEAV who did not undergo early surgery (P = 0.03).nnnCONCLUSIONnOur analysis suggests that patients with angiographic evidence of vasospasm at admission are at high risk for both symptomatic vasospasm and poor outcome. We also found that early surgery did not aggravate this risk.

Angioplasty and stenting of basilar artery stenosis: technical case report.

OBJECTIVE AND IMPORTANCEnSymptomatic basilar artery stenosis has a poor prognosis. Treatment options are limited. Surgical bypasses are technically demanding and of no proven benefit. Percutaneous angioplasty is associated with a significant complication rate, because of intraplaque dissection, restenosis secondary to vessel recoil, and embolic phenomena. A new generation of intravascular stents that are flexible enough to navigate the tortuosities of the vertebral artery may provide a new therapeutic approach. We report a case of basilar artery stenosis that was treated using stent-assisted angioplasty.nnnCLINICAL PRESENTATIONnA 56-year-old woman experienced a vertebrobasilar ischemic stroke, from which she recovered. Magnetic resonance angiography revealed severe proximal basilar artery stenosis. Brain Neurolite-single-photon emission computed tomographic scans revealed significantly decreased perfusion of the brainstem. Endovascular intra-arterial pressure measurements revealed a 35-mm Hg gradient across the lesion.nnnINTERVENTIONnThe patient underwent uncomplicated angioplasty and stenting of the proximal basilar artery, with excellent angiographic results.nnnCONCLUSIONnThe availability of new flexible intravascular stents, allowing access to tortuous proximal intracranial vessels, provides a new therapeutic approach for patients with basilar artery stenosis. Long-term follow-up monitoring is required to assess the durability of this approach.

Extracranial-intracranial arterial bypass and basilar artery ligation in the treatment of giant basilar artery aneurysms.

Two patients with giant aneurysms of the basilar artery treated with prophylactic extracranial-intracranial arterial bypass (EIAB) to the rostral brain stem before basilar artery ligation are presented. In both cases, the bypass provided considerable collateral flow to the upper basilar, posterior cerebral, and superior cerebellar arteries. Basilar artery ligation has been shown to be an effective, albeit dangerous, means of treating giant aneurysms of the basilar artery. The risk of significant brain stem ischemia after ligation is at least 30%. EIAB to the rostral brain stem should be considered whenever basilar artery ligation is performed, especially in cases where angiography demonstrates poor collateral circulation to the distal basilar artery.

Revascularization of the Rostral Brain Stem

The clinical and angiographic diagnosis of rostral brain stem vascular insufficiency is reviewed. The various possibilities for surgical revascularization of this area include anastomosis of the superficial temporal or occipital artery to the main stem of the posterior cerebral or superior cerebellar artery of their branches. A new technique for anastomosing the superficial temporal artery to the posterior cerebral artery in the tentorial incisura is presented, and other methods of rostral brain stem revascularization are considered. Indications for revascularization of the rostral brain stem are not clearly defined, but should include clinical and angiographic evidence of upper brain stem ischemia.

Effects of a mixture of a low concentration of n-butylcyanoacrylate and ethiodol on tissue reactions and the permanence of arterial occlusion after embolization.

OBJECTIVECyanoacrylates are the most commonly used liquid embolic agents. For embolization of arteriovenous malformations, a mixture of a low concentration of n-butylcyanoacrylate (NBCA) and Ethiodol (Savage Laboratories, Melville, NY) has been recommended for deeper penetration of the nidus. Dilution of NBCA, however, might result in different degrees of tissue reaction and might influence the permanence of vessel occlusion, with an increased risk of vessel recanalization. We compared tissue reactions induced by different NBCA/Ethiodol mixtures and analyzed the permanence of their embolic effects. METHODSNBCA was diluted with Ethiodol to prepare the following standard solutions: Mixture A, low concentration (NBCA/Ethiodol ratio of 20:80); Mixture B, high concentration (50:50). The study was designed in two parts, because tissue reactions after embolization are considered to be a combination of foreign body reactions to solidified material and reactions to the injured blood vessel. Foreign body reactions were studied by intramuscularly injecting both glue mixtures into the backs of 18 rats. Specimens were obtained at various times after implantation. Immunohistochemical analysis and esterase staining were used to detect macrophages and neutrophils, respectively. The densities of these inflammatory cells were calculated and statistically compared. To study the degree of vascular wall injury and the permanence of embolic effects, the renal arteries in 48 rabbits were embolized with NBCA Mixture A or B. Six specimens for each group were obtained at various times after embolization. RESULTSThere was no significant difference in foreign body reactions between groups treated with Mixtures A and B, at any time. However, the macrophage density was larger for both groups at 3 months versus 3 days and for the group treated with Mixture B at 3 months versus 2 weeks. There was no difference in the degree of vessel wall injury. None of the embolized vessels demonstrated evidence of recanalization. CONCLUSIONThe low concentration of NBCA induced a tissue response similar to that of the high-concentration form. Embolized vessels exhibited no greater incidence of recanalization. Therefore, embolization of arteriovenous malformations with diluted NBCA may be safe.

Navigability Trumps All: Stenting of Acute Middle Cerebral Artery Occlusions with a New Self- Expandable Stent

SUMMARY: Acute stroke intervention is rapidly evolving. New technologies are improving device deliverability and rates of recanalization. We describe 2 cases of acute middle cerebral artery occlusions wherein Wingspan stents could not be delivered to the occlusive site because of excessive vascular tortuosity. Merci thrombectomy was also unsuccessful. Revascularization was only achieved with deployment of the highly navigable Enterprise stent, resulting in thrombolysis in myocardial infarction 2/3 flow. Thus, all devices should be considered in the armamentarium of stroke therapy.

A grading scale to predict outcomes after intra-arterial thrombolysis for stroke complicated by contrast extravasation.

OBJECTIVEnContrast extravasation after intra-arterial thrombolysis for stroke occurs frequently and is identifiable on a computed tomographic (CT) scan, but it is often unrecognized or misdiagnosed. Few articles describing this phenomenon have been published. The clinical outcomes of patients after contrast extravasation are poorly understood. We designed a grading system to predict outcomes after contrast extravasation and tested the grading scale prospectively.nnnMETHODSnWe studied 27 patients who had contrast extravasation exhibited on a CT scan immediately after intra-arterial thrombolysis. The National Institutes of Health Stroke Scale was used to quantify neurological examinations preoperatively, postoperatively, and at follow-up an average of 3 months later. A grading scale from 0 to 10 was developed from a retrospective analysis of the first 18 patients using odds ratios and Fishers exact test. The grading system was then applied prospectively to the next 9 consecutive patients.nnnRESULTSnSix components of the grading system were weighted approximately proportional to corresponding odds ratios: 1) incomplete recanalization (3 points), 2) prolonged angiographic blush (2 points), 3) hyperdensity greater than 150 Hounsfield units (2 points), 4) lesion volume greater than 50 cc exhibited on a CT scan (1 point), 5) lesion in eloquent parenchyma (1 point), and 6) hypodensity demonstrated on an immediate postoperative CT scan (1 point). The contrast extravasation grades for each outcome category (excellent, fair, poor, died) increased in stepwise fashion. There was a direct linear correlation between the assigned grade and National Institutes of Health Stroke Scale score improvement at follow-up.nnnCONCLUSIONnThis grading system should prove useful as a preliminary guide for predicting outcomes of patients with contrast extravasation after intra-arterial thrombolysis for stroke. Further analysis in a large cohort of prospective patients is necessary to ensure extensibility.