ISSN:0268-4705    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Abdominal aortic aneurysms (AAAs) are an increasingly common and potentially lethal condition. Surgical repair of AAA is now yet performed quite safely, yet ruptured AAAs still carry mortality rates of 50% to 70%. Ultrasound screening may help identify unsuspected AAA, thereby allowing elective repair. Because AAAs too small to warrent operation still expand progressively, therapeutic approaches to suppress AAA growth would be welcome. Current concepts indicate that AAAs arise through pathophysiologic process distinct from occlusive atherosclerosis and dominated by degenerative changes in the elastic media. These include marked alterations in elastin and collagen, chronic inflammation, and features of autoimmunity, medial neovascularization, and a decrease in vascular smooth muscle cells. Proteinases associated with mononuclear inflammatory cells, particularly matrix metalloproteinases, likely mediate the degradation of structural proteins in the aortic wall. Experimental studies demonstrate that similar processes occur in an elastase-induced rodent model of AAA, providing a means by which to develop novel therapeutic strategies for this disease. Pharmacologic inhibitors of matrix metalloproteinases act to suppress aortic elastin degradation and limit the growth of experimental AAA in vivo, suggesting at least one approach that may be useful in clinical application. Further developments can be expected to increase knowledge of the pathophysiology underlying aortic aneurysm disease, ultimately providing new therapies for small AAAs based on sound understanding of disease mechanisms.

ISSN:0268-4705    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Recent investigations of patients with cerebral and peripheral arterial emboli of unknown cause suggest that paradoxical embolism through a patent foramen ovale (PFO) might be responsible for more arterial embolic events than previously realized. In most cases, however, a causal relationship between the embolic process and the PFO cannot be established with certainty. The presumptive nature of the clinical diagnosis of paradoxical embolism together with the lack of precise data on the risk of recurrent embolization do not facilitate the proper treatment of these patients. In the rare case of proved paradoxical embolism with a thrombus straddling a PFO discovered by echocardiography, the available literature suggest that embolectomy and closure of the PFO is the most logical approach. The long-term treatment of patients with presumed paradoxical embolism is controversial. Further studies are needed to assess the risk of recurrent arterial ischemic events associated with PFO, to determine which patients are at increased risk of recurrent events, and to assess the potential benefits from various therapeutic interventions (anticoagulants or antiplatelet drugs, surgical or transcatheter closure of the PFO). Otherwise, we risk exposing these patients to unnecessary treatment complications.

ISSN:0268-4705    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Although it has been the topic of intense medical and surgical attention for over 20 years, the coexistence of severe carotid artery disease in patients undergoing coronary artery bypass graft continues to be a major cause of perioperative morbidity and mortality. Refinements in diagnostic modalities, mainly by duplex ultrasonography, have improved preoperative assessment. Management possibilities vary from ignoring the carotid problem to simultaneous reconstructions. However, the best surgical option for these high-risk patients has yet to be determined because of the lack of controlled, prospective, randomized trials.

ISSN:0268-4705    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

The blue toe syndrome is characterized by tissue ischemia secondary to cholesterol crystal or atherothrombotic embolization leading to occlusion of small vessels. Embolization occurs typically from anulcerated atherosclerotic plaque located in the aorto-iliac-femoral arterial system. Clinical presentation can range from a cyanotic toe to a diffuse multiorgan systemic disease that can mimic other systemic illness. Mortality can be higher than 70% depending on the scope of the illness. Embolization can occur spontaneously or from a variety of insults such as invasive vascular procedures, anticoagulation, or thrombolytic therapy. Angiography, duplex ultrasonography, computerized tomographic scanning, and magnetic resonance imaging have been used to image the offending lesions, with angiography considered the “gold standard” despite its inherent risks. Recently, transesophageal echocardiography has been shown to be a helpful tool in imaging the thoracic aorta and delineating in great detail the anatomy of the aortic atheroma. At present, surgery remains the most viable treatment option. However, we look to the future for large randomized trials to help predict embolization and thus the propermedical therapy.

ISSN:0268-4705    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

The prevalence of acute pulmonary embolism in a general hospital was evaluated. Importantly, the prevalence of unrecognized pulmonary embolism at autopsy has not changed in three decades. Further evaluation was made of the alveolararterial oxygen difference in the diagnosis of acute pulmonary embolism. As with the partial pressure of oxygen in arterial blood, the alveolar arterial oxygen difference is usually abnormal, but a normal value does not exclude pulmonary embolism. The criteria used for a low probability interpret<n of ventilation- perfusion lung scans in the Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED) were modified. Criteria for a very low probability assessment (< 10% positive predictive value) were also determined. Progress was made with helical computed tomography and contrast-enhanced electron-beam computed tomography, but with present technology their role is limited. Selective digital subtraction angiography with a flow directed catheter seems to have been useful in some patients. A strategy for diagnosis of thromboembolic disease that uses serial noninvasive leg tests was described. The strategy reduces the number of pulmonary angiograms required. The Fourth American College of Chest Physicians Conference on Antithrombotic Therapy was published. Extensive and detailed analysis was made of the literature related to the antithrombotic treatment of pulmonary embolism and the use of antithrombotic therapy during pregnancy.

ISSN:0268-4705    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

The use of thrombolytic agents (plasminogen activators) in the early moments of ischemic stroke to achieve recanalization and potential neurologic improvement has been actively studied over the past 10 years. In the same period, endovascular techniques for cerebral revascularization have evolved significantly. Recent phase III studies, following angiography-based phase I and II studies of plasminogen activators in stroke, have described evidence of clinical benefit and contributors to morbidity (/e, symptomatic hemorrhage) and mortality that limit the applicability of this approach. The limited formalized experience with percutaneous transluminal balloon angioplasty and stent placement in the carotid artery and cerebral circulation has given rise to concerns about the safety and appropriateness of the procedures in this territory. However, several prospective series support the feasibility of well-designed clinical trials.

ISSN:0268-4705    

出版商:OVID    

年代:1996

数据来源: OVID