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Biomedical subjects

Jay U Howington

Publications and source records attributed to Jay U Howington.

10 recordsLinked to original sources
PubMed2005

Submaximal angioplasty and staged stenting for severe posterior circulation intracranial stenosis: a technique in evolution.

INTRODUCTION: Severe medically refractory intracranial stenosis portends a grave prognosis. Recent advances in stent technology have enabled clinicians to treat these lesions. Evidence in the coronary literature suggests that stenting without predilation angioplasty is as safe and effective as stenting immediately preceded by predilation angioplasty for the treatment of severely stenotic lesions. Because of marked differences in vessel histology and differences in the sensitivity of the cerebral and coronary vascular beds to embolic insult, direct stenting of severe intracranial stenoses may be more prone to neurological complications than a conventional or staged stenting procedure. METHODS: We reviewed our clinical experience with conventional, direct, and staged stenting for high-grade stenoses involving the posterior intracranial circulation. We also reviewed the literature and experimental data supporting the rationale for staged stenting. RESULTS: In our experience, no permanent neurological morbidity was identified in four patients treated with a staged approach. In contrast, one of three patients with conventional stenting of the basilar artery and two of four patients treated with direct basilar stenting had permanent neurological sequelae. CONCLUSION: For patients with high-grade posterior circulation intracranial stenoses involving the perforator-rich zones of the basilar artery, staged stenting may reduce procedure-related morbidity. A staged approach allows for plaque stabilization resulting from post-angioplasty fibrosis, which may protect patients from "snow-plowing," embolic shower of debris, or dissection. Further clinical, in vivo, and histological investigation is warranted.

Angioplasty, Balloon↗
PubMed2004

Patient selection for revascularization in cervical carotid artery disease: angioplasty and stenting vs. endarterectomy.

Cervical carotid stenosis is a major cause of stroke and disability. Although carotid endarterectomy is an established and effective treatment for some patients with carotid artery stenosis, angioplasty and stenting has emerged in recent years as a viable alternative, particularly for patients who may be less suited for surgery. This article reviews patient selection for the two alternative approaches. The authors review the findings of the major clinical trials of carotid endarterectomy, summarize the development of carotid angioplasty and stenting, and identify patient characteristics that may guide selection of surgical or endovascular treatment.

Angiography↗
PubMed2004

Sirolimus-eluting stents in the canine cerebral vasculature: a prospective, randomized, blinded assessment of safety and vessel response.

OBJECT: Use of the sirolimus-eluting stent has led to a reduction of in-stent stenosis following treatment of coronary atherosclerosis, whereas treatment of intracranial atherosclerosis with bare-metal stents results in excessive restenosis rates of approximately 40%. Neurotoxicity effects and vessel injury are unknown in the cerebral vasculature. To assess the safety profile and vascular effects of sirolimus-coated stents, the authors conducted a prospective comparative study in which drug-eluting and bare-metal stents were implanted in the canine basilar artery (BA). METHODS: Sixteen mongrel dogs were randomized (eight animals per group) to receive either bare-metal 1.5 x 8-mm (six-cell) stents or sirolimus-eluting stents of the same dimensions. Interventionists, histopathologists, and histopathology technicians who participated in the study were blinded to the stent characteristics. Stents were implanted in the canine BA. Serial peripheral blood samples were obtained during the 1st week after implantation to determine the time-dependent serum concentration of sirolimus. Follow-up angiographic studies were performed 30 days after stent implantation to assess the effects of stent placement on the BA and brainstem perforating vessels. Explantation of the stent and BA was performed immediately after angiography by using a pressurized formalin fixation procedure. Histological and computer-assisted morphometric analyses of specimens obtained in each animal were performed. Sirolimus could not be detected in peripheral blood samples obtained later than 24 hours posttreatment. On follow-up angiography, all perforating vessels observed on initial angiograms remained patent, and no evidence of parent vessel damage or pseudoaneurysm formation was observed. Explanted vessels and brainstem sections did not demonstrate evidence of histological neurotoxicity, such as gliosis or infarction. No significant differences were found in the time to endothelialization of bare-metal and sirolimus-coated stents. Smooth-muscle cell (SMC) proliferation, the putative agent for restenosis, was lower in animals receiving sirolimus-coated stents (p = 0.003). Additionally, intimal fibrin density was increased in the dogs treated with sirolimus-coated stents (p < 0.0001). Histological evidence of an inflammatory response demonstrated a trend toward a reduced response in the sirolimus group (mean 0.58) compared with the bare-metal group (mean 0.83, p = 0.33). CONCLUSIONS: No neurotoxic effects were observed in the intracranial vessel walls or brainstem tissue in which sirolimus-coated stents were implanted. Compared with bare-metal stents, the sirolimus-coated devices did not impair endothelialization and, furthermore, tended to reduce the proliferation of SMCs. These findings indicate that sirolimus-coated devices may inhibit in-stent stenosis. Further studies with longer-term follow up are required to assess the restenosis rates of sirolimus-coated stents implanted in the intracranial vasculature.

Animals↗
PubMed2003

Cocaine use as a predictor of outcome in aneurysmal subarachnoid hemorrhage.

OBJECT: The goal of this study was to analyze the relationship between cocaine use and outcomes of aneurysmal subarachnoid hemorrhage (SAH). METHODS: A retrospective review was performed of the medical records of patients with intracranial aneurysms treated at a single institution between January 1996 and December 2001. Only patients who presented with SAH were included in the study. The covariates chosen for the statistical analysis included the following: patient age, sex, and race; systolic and mean arterial blood pressure measurements on hospital admission; Hunt and Hess and Fisher grades; pre-existent major systemic disease; and history of alcohol, tobacco, or cocaine use. The Glasgow Outcome Scale (GOS) was used to standardize outcome and was dichotomized such that a score between 1 and 3 was considered a poor outcome and a score of 4 or 5 was considered a favorable outcome. The records of 151 patients were reviewed and 108 of these presented with aneurysmal SAH. Of these 108 patients, 36 (33.3%) had used cocaine within 24 hours before presentation. A Hunt and Hess grade of IV or V was assigned to 20 (55.6%) of 36 patients who used cocaine, compared with eight (11.1%) of 72 patients who did not; this difference was found to be statistically significant (p < 0.0001). Twenty-eight patients (77.8%) in the cocaine user group and 20 patients (27.8%) in the non-cocaine user group experienced clinically significant, angiographically confirmed vasospasm during their hospital course (p < 0.0001). Cocaine use was associated with a 2.8-fold greater risk of developing vasospasm (95% confidence interval [CI] 1.86-4.22). A GOS score of 1, 2, or 3 was assigned to 33 patients (91.7%) in the cocaine user group and to 20 patients (27.8%) in the non-cocaine user group (p < 0.0001). Cocaine use was associated with a 3.3-fold greater risk of poor outcome (95% CI 2.24-4.85). This association was found to be independent of Hunt and Hess grade as well as of vasospasm. CONCLUSIONS: Cocaine adversely affects both the presentation of and outcome in patients with aneurysmal SAH who are undergoing treatment for this disease. The vasoactive properties of the drug appear to aggravate the already tenuous situation of SAH and increase both the occurrence and influence of cerebral vasospasm. Statistical analysis demonstrates that cocaine directly affects both presentation and outcome in a significant manner. It is the authors' interpretation of the results of this retrospective review that cocaine use negatively affects outcome to such an extent that it should be considered equal to the presence of a major systemic illness when determining Hunt and Hess grade.

Adult↗
PubMed2002

Should interventional cardiologists treat ischemic strokes? A global perspective.

Stroke is the third leading cause of death and the leading cause of severe neurological disability in our nation. The stroke death rate has the potential to reach epidemic proportions as the elderly segment of the population continues to rise. There is an insufficient number of trained physicians to supply the care for this patient population. The logical source for qualified physicians to care for these patients is the interventional cardiologist. We review the recent intraarterial therapy trials and detail the training necessary to allow interventional cardiologists to treat ischemic strokes.

Cardiology↗