Antithrombotic therapy for cerebrovascular disorders.
Explore the source record for details and available documents.
Biomedical subjects
Publications and source records attributed to R G Hart.
Explore the source record for details and available documents.
Cardiogenic embolism is responsible for about 60,000 strokes each year in the United States. A number of cardiac conditions are known to increase the risk of stroke, including nonvalvular atrial fibrillation and ischemic heart disease. The difficulty lies in determining whether the potential cardioembolic source alone is the mechanism for the stroke. The lack of sensitive and specific clinical diagnostic criteria for cardiogenic stroke has important implications for both primary and secondary stroke prevention.
Carbon monoxide (CO) is the leading toxic cause of death in the United States today. Unsuspected exposure to this gas will sometimes result in clinically significant, but undiagnosed, toxicity. A high incidence of such unsuspected exposures would make screening for these worthwhile among high-risk populations. We conducted a two-part study to determine the value of screening for unsuspected CO exposure in a population of patients presenting to an emergency department. The first part of our study involved the prospective screening of ED patients using CO breath analysis, regardless of their chief complaint. In the second part, COHGB levels of all patients who underwent arterial blood gas analysis during the study period were reviewed retrospectively. Of 1,038 patients screened by this combined approach, only 29 (2.8%) had abnormal CO breath readings and/or COHGB levels. Of a condensed subgroup of 152 patients defined retrospectively by chief complaint, eight (5.3%) had abnormal values. We conclude that routine screening of ED patients for unsuspected CO exposure is not practical. Although yield increases when patients are screened in a more selective manner on the basis of chief complaint, such an increase still does not appear to justify the screening process.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Neurologic complications, particularly brain infarction (ischemic stroke), are frequent and serious sequelae of total artificial heart (TAH) implantation. Most strokes that occur in TAH patients are due to embolism of thrombotic fragments originating on prosthetic surfaces. The emboli tend to lodge in the middle cerebral artery or its cortical branches and cause cortical syndromes. Cardioembolic strokes are characteristically heralded by the abrupt onset of a maximal neurologic deficit in an awake, often active patient. Cardioembolic strokes have a tendency to undergo hemorrhagic transformation. Anticoagulation is a major issue in stroke management: In anticoagulated patients, hemorrhagic transformation often results in major neurologic worsening; therefore, this risk must be weighed against the danger of recurrent embolism in the absence of anticoagulation. We recommend avoiding anticoagulation during the initial 24 to 48 hours after a stroke, especially in patients with large cardioembolic infarcts. Because of the many invasive procedures producing bacteremia in TAH patients, combined with the large area of prosthetic surfaces, infective endocarditis is a potential concern. Weighing the risks and benefits of anticoagulation in patients with infective endocarditis is likely to produce a controversial choice. Anticoagulation should probably be continued in such patients if they have total artificial hearts. The following article discusses the foregoing issues and presents recommendations for managing acute stroke in TAH patients.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
The use of antithrombotic therapy of any type assumes a thrombotic mechanism for the patient's brain ischemia. Typical, but by no means specific, clinical and radiologic features of atherothrombotic, lacunar and embolic brain ischemia are outlined. The indications for anticoagulant therapy include progressing stroke and cardiogenic brain embolus. According to previous randomized trials, transient ischemic attacks should be managed with aspirin, 1.0 to 1.5 g daily, pending the results of studies of smaller aspirin doses and other platelet-active drugs. In patients with a suspected cardiogenic brain embolus, anticoagulation should be withheld pending the results of a computed tomographic scan done 24 to 48 hours from onset. If there is no evidence of hemorrhagic transformation or a large area of infarction and the patient does not have sustained hypertension, heparin therapy should be initiated in an effort to prevent a recurrent embolus.
Antithrombotic therapy in prevention and management of stroke is evolving rapidly as new clinical data better define indications. Stroke is a syndrome with several pathophysiologic bases, not one clinical entity. Optimal use of medical and surgical therapy requires definition of the specific mechanism of brain ischemia in the individual patient.
Explore the source record for details and available documents.