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Biomedical subjects

K Sigmon

Publications and source records attributed to K Sigmon.

9 recordsLinked to original sources
PubMed2000

Inhibition of platelet aggregation with a glycoprotein IIb-IIIa antagonist does not prevent thrombin generation in patients undergoing thrombolysis for acute myocardial infarction.

Thrombin activity has been implicated as a mechanism for failed reperfusion and reocclusion following thrombolysis. Aggregating platelets provide a phospholipid surface on which prothrombin is cleaved to form thrombin. We examined markers of thrombin generation and activity in patients enrolled in a randomized, placebo-controlled, dose escalating trial of the platelet glycoprotein IIb-IIIa inhibitor eptifibatide (Integrilintrade mark) administered concomitantly with tissue plasminogen activator for the treatment of myocardial infarction. Measurements were obtained at baseline, at 90 minutes, and at 6, 12, and 24 hours after starting therapy. Eptifibatide inhibited platelet aggregation in response to 20 microM ADP. Levels of fibrinopeptide A (FPA), thrombin-antithrombin complexes (TAT), and prothrombin fragment 1.2 (F1.2) were not lower in patients treated with eptifibatide than in the control group. In the course of dose escalation, two groups of patients received the same 135 microg/kg bolus of eptifibatide, one with and one without a heparin bolus. FPA levels were dramatically lower in the heparin-treated patients. Levels of FPA, TAT, and F1.2 were not higher in patients with than in those without recurrent ischemia, or in patients without than in those with Thrombolysis in Myocardial Infarction (TIMI) grade 3 angiographic flow at 90 minutes. These data suggest that thrombin generation and activity persist following thrombolysis, despite inhibition of platelet aggregation, and that treatment with inhibitors of thrombin activity may be required even when glycoprotein IIb-IIIa inhibitors are used.

Cohort Studies↗
PubMed1999

Nursing interventions to decrease bleeding at the femoral access site after percutaneous coronary intervention. SANDBAG Nursing Coordinators. Standards of Angioplasty Nursing Techniques to Diminish Bleeding Around the Groin.

BACKGROUND: This trial is the first prospective, multicenter clinical nursing trial conducted to measure the effect of nursing interventions on bleeding at the femoral access site after percutaneous coronary intervention with or without a potent antiplatelet agent given along with heparin and aspirin. OBJECTIVE: To measure the relationship between nursing interventions and complications at the arterial access site in patients undergoing percutaneous coronary interventions and to recommend a standard of care to minimize bleeding complications. METHODS: In a descriptive, correlational 4010-patient study, nursing care interventions after coronary procedures were measured. Observed standards of care were assessed, and regression techniques were used to evaluate nursing interventions and the effect of the interventions on bleeding at the access site after percutaneous coronary procedures. RESULTS: Several significant correlations between nursing interventions and the occurrences of moderate to severe bleeding at the access site were found; however, most interventions had little effect. The most significant factors in decreasing complications at the access site were early removal of the arterial sheath, the type of pressure mechanism used to achieve arterial hemostasis, staffing allocation, and the person and method used to remove the sheath. CONCLUSION: Many nursing interventions after percutaneous coronary intervention have become routine in the absence of clinical outcome data. Most nursing interventions aimed at decreasing bleeding at the vascular access site increase nursing workload but do not significantly affect bleeding in the groin. These results underscore the importance of continued clinical research studies to validate nursing practice on the basis of patients' outcomes.

Angioplasty, Balloon, Coronary↗
PubMed1995

Bleeding complications with the chimeric antibody to platelet glycoprotein IIb/IIIa integrin in patients undergoing percutaneous coronary intervention. EPIC Investigators.

BACKGROUND: The potential for novel antiplatelet and antithrombin agents to contribute to periprocedural bleeding complications of percutaneous coronary revascularization is poorly defined. In the Evaluation of c7E3 Fab in Preventing Ischemic Complications of High-Risk Angioplasty (EPIC) trial, the periprocedural use of aspirin, heparin, and a chimeric antibody to the platelet glycoprotein IIb/IIIa integrin c7E3 Fab in 2099 patients significantly reduced postprocedural ischemic complications and 6-month clinical restenosis but was associated with increased procedural bleeding complications. We review these complications and describe clinical and procedural variables associated with increased bleeding complications in the EPIC trial. METHODS AND RESULTS: Patients with high-risk clinical or lesion morphological characteristics were randomized to receive placebo bolus plus placebo infusion, c7E3 Fab bolus plus placebo infusion, or c7E3 Fab bolus plus c7E3 Fab infusion. Patients received periprocedural aspirin and intravenous heparin continued for a minimum of 12 hours after the procedure. Outcomes reflecting bleeding complications were measured: transfusions, decreased hemoglobin, and an index including both parameters. Major bleeding complications unrelated to bypass surgery occurred in 3.3%, 8.6%, and 10.6%, and blood product transfusions were used in 7.5%, 14.0%, and 16.8% of patients treated with placebo, bolus c7E3 Fab, and bolus plus infusion c7E3 Fab, respectively (both P < .001). Most major bleeding complications occurred at the femoral access site, regardless of treatment. Intracranial hemorrhage (0.3%) and death (0.09%) attributable to major bleeding complications were rare. Multivariable regression analyses identified several variables significantly and independently related to major bleeding complications or greater blood loss, including greater age, female sex, lower weight, c7E3 Fab therapy, and duration and complexity of the index procedure. Major bleeding complications and blood loss in patients receiving bolus plus infusion were not significantly greater than in those receiving bolus alone (P = .38 and P = .14, respectively). CONCLUSIONS: Bleeding complications unrelated to bypass surgery were two to three times more frequent in patients receiving c7E3 Fab than in those receiving placebo, but most were transient and well tolerated. Risk-factor analysis and modification of concomitant antithrombotic and antiplatelet treatment strategies may aid in reducing bleeding complications and enhancing clinical benefit in patients receiving c7E3 Fab during percutaneous coronary revascularization.

Aged↗
PubMed1993

Lack of impact of early catheterization and fibrin specificity on bleeding complications after thrombolytic therapy. The TAMI Study Group.

OBJECTIVES: The aim of this study was to assess the hemorrhagic risk associated with fibrin-specific thrombolytic therapy and invasive procedures with acute myocardial infarction. BACKGROUND: Successful coronary artery reperfusion has important prognostic implications. Because immediate coronary angiography is the only method proved to differentiate early fibrinolytic success from failure, its use may be important for selected patients. METHODS: Five hundred seventy-five patients were evaluated with six combined thrombolytic and catheterization strategies. Patients were randomized to intravenous urokinase alone, recombinant tissue-type plasminogen activator (rt-PA) alone, or both; simultaneously they were randomized to an immediate versus a deferred catheterization strategy. Hemorrhagic events were assessed. The correlation of hemorrhage with clinical and hemostatic variables was evaluated. Prespecified transfusion criteria were employed. RESULTS: No difference in baseline characteristics or in hemorrhagic complications was noted among the three thrombolytic regimens. Although mild (< 250 ml) bleeding was more common in the group with immediate catheterization, no clinically significant difference among catheterization groups was seen in moderate to life-threatening hemorrhagic events. Most bleeding occurred at vascular access sites, yet severe and life-threatening hemorrhage occurred in < 1% of patients. Baseline and nadir fibrinogen levels, change in baseline fibrinogen levels and peak fibrin and fibrinogen degradation products did not correlate with bleeding risk. A clinical predisposition for bleeding was observed in women as well as older (> or = 65 years) and lighter (< or = 70 kg) patients. With prespecified transfusion criteria, only a minimal increase in blood product usage was noted with immediate catheterization. CONCLUSIONS: Immediate cardiac catheterization can be accomplished without a clinically significant difference in bleeding risk. Fibrin specificity offers no clear advantage in reducing hemorrhagic risk. Bleeding risk correlates best with baseline patient characteristics. Finally, the amount of blood transfused can be reduced with lower transfusion criteria.

Cardiac Catheterization↗
PubMed1992

Accelerated plasminogen activator dose regimens for coronary thrombolysis. The TAMI-7 Study Group.

To determine the clinical profile and efficacy of accelerated recombinant tissue-type plasminogen activator (rt-PA) dose regimens, five different strategies of thrombolytic therapy in a total of 232 patients were systematically evaluated in the setting of acute myocardial infarction. The fifth strategy involved a combination of accelerated rt-PA and intravenous urokinase (regimen E). A weight-adjusted dose of 1.25 mg/kg body weight of tissue plasminogen activator over 90 min (regimen C) yielded the highest coronary patency rate (83%) at acute angiography. The associated in-hospital reocclusion rate for this regimen was low (4%). An exaggerated (60-min) dosage regimen yielded an inferior coronary patency rate (63%). Combination therapy (regimen E) was associated with a 72% patency rate and 3% reocclusion rate. Marginal improvement in global ejection fraction and regional wall function was demonstrated with all strategies by predischarge catheterization. Bleeding complications were most common at the periaccess site and were not different from those in previous experiences reported with conventional 3-h dosing regimens. Measurements of baseline, 30-min and 3-h levels of tissue plasminogen activator, fibrinogen and fibrin(ogen) degradation products were obtained. At 3 h, fibrinogen levels of less than 1 g/liter were demonstrated with combination therapy (regimen E) as well as with regimen C. Major clinical outcomes including death, reocclusion and reinfarction also showed a tendency to be less common with regimen C. Therefore, although accelerated dose regimens of rt-PA do not reliably yield acute coronary patency rates greater than 85%, an acute coronary patency rate of approximately 85% can be approached.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Identification of acute myocardial infarction patients suitable for early hospital discharge after aggressive interventional therapy. Results from the Thrombolysis and Angioplasty in Acute Myocardial Infarction Registry.

BACKGROUND: Very early (day 4) hospital discharge has recently been proposed for selected patients with acute myocardial infarction (MI). The purpose of this study was to determine the most useful factors for identifying acute MI patients treated with aggressive interventional therapy who could be safely discharged on day 4. METHODS AND RESULTS: We studied 708 patients enrolled in the Thrombolysis and Angioplasty in Acute Myocardial Infarction trials I-III. Patients dying in the first 3 days and those with early (days 1-3) emergency coronary artery bypass graft surgery (CABG), late elective CABG (greater than or equal to day 4), or urgent/emergency CABG resulting from a late elective coronary angioplasty were excluded. The remaining 580 patients were randomly divided into a training sample (group 1) that was used to build a logistic regression model for predicting the absence of a late major complication and a test sample (group 2) that was used to validate this model. For this study, patients were considered appropriate for day 4 hospital discharge if they did not experience any of the following for 30 days after MI: death, reinfarction, cardiogenic shock, pulmonary edema, sustained hypotension, sustained ventricular tachycardia, high-grade atrioventricular block, acute ventricular septal defect, and recurrent ischemia necessitating urgent CABG. In group 1, four variables were independent predictors of freedom from late major complications: absence of early sustained ventricular tachycardia or ventricular fibrillation, absence of early sustained hypotension or cardiogenic shock, fewer coronary arteries with significant (greater than or equal to 75%) stenosis, and a higher left ventricular ejection fraction. In group 2, 23% of patients had a logistic model prediction of a 3% or less chance of a late complication. These patients had no deaths or reinfarctions by day 30 and a 3% late major complication rate. CONCLUSIONS: The results of early cardiac catheterization and the absence of selected early (days 1-3) major complications do allow identification of a low risk subgroup of acute MI patients that may be suitable for very early discharge.

Angioplasty, Balloon, Coronary↗
PubMed1990

Results of high dose intravenous urokinase for acute myocardial infarction.

To determine the outcome of patients after treatment with high-dose intravenous urokinase (3 million U) 102 patients were prospectively evaluated in the setting of acute myocardial infarction. The first 61 patients received intravenous urokinase as a continuous infusion and the last 41 patients were treated with an initial 1.5 million U intravenous bolus. Sixty-two percent of all patients had patent infarct-related arteries by the time of immediate angiography (median time 2.2 hours), which was performed in all patients. There was no significant difference in patency rates between patients treated with or without an initial intravenous bolus. Twenty-eight (28%) patients developed clinical evidence of recurrent ischemia (death, reocclusion, emergency angioplasty, urgent bypass surgery) during hospitalization, whereas only 7 (7%) developed angiographically documented reocclusion. Of 28 patients who failed to achieve successful reperfusion at the time of immediate catheterization, rescue angioplasty was technically successful in establishing reperfusion in all but 1 patient. No significant improvement in median global left ventricular function was seen between immediate (48%) and follow-up catheterization (48%). Significant bleeding complications were unusual except in 1 patient who experienced an intracranial hemorrhage. Eight (8%) patients died during hospitalization. Therefore, the use of high-dose intravenous urokinase in patients with acute myocardial infarction is associated with a 62% patency rate, a low incidence of reocclusion and bleeding complications and a high technical success rate with rescue angioplasty at the time of immediate catheterization.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1989

Pharmacodynamics of thrombolysis with recombinant tissue-type plasminogen activator. Correlation with characteristics of and clinical outcomes in patients with acute myocardial infarction. The TAMI Study Group.

Coagulation analysis was performed on blood samples from 386 patients with acute myocardial infarction drawn before, during, and after a continuous intravenous infusion of 150 mg recombinant tissue-type plasminogen activator (rt-PA) (Activase). Plasma rt-PA rose to peak levels of 2.1 +/- 3.1 micrograms/ml (mean +/- SD). Fibrinogen levels measured by coagulation rate and by sulfite precipitation decreased from baseline levels of 3.0 +/- 0.9 and 3.2 +/- 1.0 g/l, respectively, to nadir levels of 1.4 +/- 0.75 and 1.8 +/- 0.92 g/l, respectively, and were associated with peak levels in serum of fibrinogen-degradation products (FDP) of 230 +/- 470 micrograms/ml. Forty percent of patients experienced a nadir functional-fibrinogen level of less than 1.0 g/l, whereas 20% fell below 0.5 g/l. Nadir fibrinogen levels did not correlate with patency of the infarct-related coronary artery at 90 minutes or with risk of coronary vessel reocclusion within 7-10 days. However, the risk of coronary artery reocclusion was inversely related to the baseline functional fibrinogen level (p = 0.0008), with the magnitude of its drop to nadir level (p = 0.0003) as well as to peak levels of FDP (p = 0.038). Quantitative blood loss correlated with all markers for systemic fibrinogenolysis including nadir fibrinogen level (r = -0.20, p = 0.0011), percent decrease of fibrinogen (r = 0.22, p = 0.001), and peak FDP levels (r = 0.14, p = 0.020). Both patients who experienced intracranial hemorrhage presented with high baseline fibrinogen levels and experienced extensive degradation of coagulable fibrinogen. Overall, patients at greatest risk of systemic fibrinogenolysis tended to be relatively older women with lower body weight.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Coagulation↗