Infarct artery patency rates at 90 minutes after coronary thrombolysis using recombinant tissue-type plasminogen activator (rt-PA) with and without concurrent heparin anticoagulation have been shown ...to be comparable. The contribution of heparin to efficacy and safety after thrombolysis with rt-PA is unknown. In this pilot study, 84 patients were treated within 6 hours of onset of acute myocardial infarction (mean of 2.7 hours) with the standard dose of 100 mg of rt-PA over 3 hours. Forty-two patients were randomized to receive additionally immediate intravenous heparin anticoagulation (5,000 U of intravenous bolus followed by 1,000 U/hour titrated to a partial thromboplastin time of 1.5 to 2.0 times control) while 42 patients received rt-PA alone. Coronary angiography performed on day 3 (48 to 72 hours, mean 57) after rt-PA therapy revealed infarct artery patency rates of 71 and 43% in anticoagulated and control patients, respectively (p = 0.015). Recurrent ischemia or infarction, or both, occurred in 3 (7.1%) anticoagulated patients and 5 (11.9%) control patients (difference not significant). Mild, moderate and severe bleeding occurred in 52, 10 and 2% of the group receiving anticoagulation, respectively, and 34, 2 and 0% of patients in the control group, respectively (p = 0.006). These data indicate that after rt-PA therapy of acute myocardial infarction, heparin therapy is associated with substantially higher coronary patency rates 3 days after thrombolysis but is accompanied by an increased incidence of minor bleeding complications.
Intravenous heparin is routinely given after thrombolytic therapy for patients with acute myocardial infarction in the United States and in some, but by no means all, other countries. Several trials ...have documented improved infarct-artery patency in patients treated with heparin; however, none was large enough individually to assess the effect of heparin on clinical outcomes. We performed a systematic overview of the 6 randomized controlled trials (1,735 patients) to summarize the available data concerning the risks and benefits of intravenous heparin versus no heparin after thrombolytic therapy. Mortality before hospital discharge was 5.1% for patients allocated to intravenous heparin compared with 5.6% for controls (relative risk reduction of 9%, odds ratio 0.91, 95% confidence interval 0.59 to 1.39). Similar rates of recurrent ischemia and reinfarction were observed among those allocated to heparin therapy or control. The rates of total stroke, intracranial hemorrhage, and severe bleeding were similar in patients allocated to heparin; however, the risk of any severity of bleeding was significantly higher (22.7% vs 16.2%; odds ratio 1.55, 95% confidence interval 1.21 to 1.98). There was no significant difference in the observed effects of heparin between patients receiving tissue-type plasminogen activator and those receiving streptokinase or anisoylated plasminogen streptokinase activator complex, or between patients who did and did not receive aspirin. The findings of this overview demonstrate that insufficient clinical outcome data are available to support or to refute the routine use of intravenous heparin therapy after thrombolysis. It is not known if these findings are due to lack of statistical power, inappropriate levels of anticoagulation, or lack of benefit of intravenous heparin. Large randomized studies of heparin (and of newer antithrombotic regimens) are needed to establish the role of such therapy.
Background This study was designed to investigate the efficacy of alteplase double-bolus dosing compared with the front-loaded 90-minute infusion regimen in patients with acute myocardial infarction. ...Recent pilot studies have suggested that bolus dosing may provide improved efficacy in establishing early, complete, and sustained patency of the infarct-related artery in the thrombolytic treatment of acute myocardial infarction.
Methods and Results In this multicenter, randomized, open-label trial, 461 patients with acute myocardial infarction received 100 mg alteplase as a front-loaded 90-minute infusion (15 mg bolus, then 50 mg over a 30-minute period, then 35 mg over a 60-minute period) or double bolus (two 50 mg bolus injections 30 minutes apart). All patients also received intravenous heparin and oral aspirin during and after alteplase treatment. The 90-minute angiographic patency rates were 74.5% in the double-bolus group and 81.4% in the infusion group (
p = 0.08). Patency rates were also comparable for the two groups at 60 minutes (76.8% vs 77.5%) and 24 hours (95.5% vs 93.5%) after initiation of treatment. In-hospital mortality rates were 4.5% in the bolus group and 1.3% in the infusion group (
p = 0.04); 30-day mortality rates were 4.5% and 1.7%, respectively (
p = NS). The two groups were comparable in frequency of all other adverse events.
Conclusions Double-bolus alteplase administration produced reperfusion rates comparable to front-loaded infusion, but in-hospital and 30-day mortality rates were higher in the double-bolus group. These findings are in agreement with those of the COBALT megatrial, which also reported a trend to higher mortality rates with double-bolus dosing. (Am Heart J 1998;136:741-8.)
A retrospective study of the clinical and biochemical data of all patients with end-stage renal disease who underwent 2-dimensional echocardiography at Tulane Medical Center between 1982 and 1986 was ...performed. Complete echocardiographic data were available for comparison in 53 patients. Highly reflective echoes were judged to be present in the myocardium of 81% of the patients. This characteristic is described as a "glistening speckled appearance." Patients with this characteristic had significantly greater left ventricular mass index (p = 0.0021).
Development of rural landscapes is converting once-vast expanses of open space into pockets of habitat where wildlife populations exist in isolation from other members of their species. The central ...concept of metapopulation dynamics -- that a constellation of partially isolated patches can yield overall stability to a system that is chaotic at the level of the individual patch -- offers an important new way of thinking about the conservation and management of populations dispersed among small habitat fragments. This approach is proving to be a rich resource for biologists hoping to arrest the current catastrophic loss of biodiversity.This volume provides a comprehensive overview of the subject, addressing the needs of an applied professional audience for comprehensible information to integrate into their practices. Leading conservation biologists, ecologists, wildlife managers, and other experts consider the emergence and development of metapopulation theory and explore its applicability and usefulness to real-world conservation programs. Conservation is essential reading for anyone working in the field of wildlife conservation and management.
Purchasers of newly-issued shares of preferred stock typically seek an opinion from the Company's counsel that the shares have been duly authorized and validly issued and are fully paid and ...nonassessable. This article amplifies the discussion in Section 6.2.1 of the 1998 TriBar Report of the meaning of the "duly authorized" part of this opinion when it is given on preferred stock. Modern corporation statutes typically grant corporations the authority to create preferred stock having terms as they may desire, subject only to compliance with the requirements of that statute and the requirements, if any, of the corporation's charter. Opinion recipients sometimes request that the opinion expressly confirm that the terms of the preferred stock do not violate the state corporation statute and the Company's charter. When preferred stock provisions are relatively straightforward, opinion preparers usually have little difficulty giving an unqualified duly authorized opinion.
