Community hospital administration of intravenous tissue plasminogen activator in acute myocardial infarction: improved timing, thrombolytic efficacy and ventricular function.

As an investigational fibrinolytic agent for acute myocardial infarction, intravenous recombinant tissue-type plasminogen activator (rt-PA) has been administered primarily in tertiary care and university centers. To determine the value of early initiation of such therapy, two satellite community hospital emergency rooms were established for use of rt-PA and the experience was compared among 142 consecutive patients who were transferred to a regional center for acute cardiac catheterization after intravenous rt-PA therapy. In Group I (n = 19), patients received rt-PA after interhospital transport to the regional center, but before cardiac catheterization. In Group II (n = 70), rt-PA therapy was initiated by the helicopter physician and nurse team after their arrival at the local community hospital emergency room. Group III patients (n = 53) had rt-PA administered in the local community hospital by the emergency room physician. Group III patients had earlier initiation of therapy (2.1 +/- 0.8 hours in Group III versus 3.8 +/- 1.2 hours in combined Groups I and II, p less than 0.001) and an increased rate of infarct vessel recanalization on the 90 minute coronary angiogram (81 in Group III versus 67% in combined Groups I and II, p = 0.057). The patients in Group III had a higher acute left ventricular ejection fraction (54 +/- 8% versus 50 +/- 9.5% in combined Groups I and II, p less than 0.01) and a trend toward an increased 7 day ejection fraction (55.5 +/- 9% versus 51.7 +/- 9.5%, respectively, p = 0.08).(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical controversies surrounding thrombolytic therapy in acute myocardial infarction.

The treatment of acute myocardial infarction has changed tremendously in the past decade because thrombolytic therapy has become the treatment of choice for the patient with acute myocardial infarction. Although many issues have been resolved, several controversial issues remain unresolved. This article addresses thrombolytic agents in terms of their superiority in achieving infarct vessel patency and mortality reduction as well as the role of thrombolysis in patients who present with chest pain of greater than 6 hours' duration, who are elderly, and who have an inferior infarction.

Pharmacologic review of thrombolytic agents.

Thrombolytic therapy has significantly reduced the morbidity and mortality that was once associated with acute myocardial infarction. Because of the substantial benefits associated with this therapy, investigation has intensified in search of the optimal agent or agents. Five agents are currently being investigated individually and in various combinations to determine which agent(s) will outperform the others in terms of reperfusion, patency, mortality reduction, and clinical events. Two of the agents, t-PA and scu-PA, are considered fibrin selective, whereas the other three, streptokinase, urokinase and APSAC are nonselective. Whether this distinction provides substantial benefit is still not known. All of the FDA-approved agents (streptokinase, t-PA, and APSAC) have demonstrated survival benefit and will continue to be administered in AMI patients. In addition, the 1990s begins a new era that includes broadened selection criteria for AMI patients as well as expanding cardiovascular indications for thrombolytic therapy. The challenge to nurses is to improve and implement nursing care practices at the same rapid pace set by the medical discipline. This includes astute assessment and observational skills necessary to prevent and detect potential complications associated with thrombolytic therapy. Rapidly changing medical techniques mandate ongoing nursing research, which is needed to determine the most effective interventions in reducing complications associated with thrombolytic therapy and in promoting positive adaptive behaviors in the AMI patient. Thrombolytic therapy is an intervention for the 1990s, and nursing care is essential in maintaining the beneficial effects of this dynamic therapy.

Comparison of thrombolytic agents: mechanisms of action.

The new generation of plasminogen activators promises certain advantages over the first-generation agents, particularly enhanced clot specificity. The tissue distribution, half-life, therapeutic profile, and optimum dosage, however, need to be evaluated for each chemically different agent. Whatever advantages these third-generation agents offer over the existing natural prototypes of the plasminogen activators will not be determined for some time. In addition, because an "agent of choice" has not been identified at this time, critical care nurses must understand the mechanisms of action of the various thrombolytic agents to ensure accurate and appropriate assessment, problem identification, and intervention in this era of reperfusion with thrombolytic therapy.

Intermittent, ambulatory dobutamine infusions in patients with severe congestive heart failure.

Thirteen ambulatory patients with severe congestive heart failure were treated with weekly, outpatient 48-hour infusions of dobutamine. All 13 patients had at least a 25% increase in cardiac output during initial dobutamine titration, with a corresponding improvement in systemic vascular resistance. Improvement in functional class was achieved in only seven patients. Additionally, only three patients survived the 26-week study period. Although no change in ventricular ectopy was noted during the initial dobutamine infusions, six patients experienced sudden death; three other patients died of progressive heart failure and one died from pulmonary embolism. These data suggest that chronic intermittent ambulatory dobutamine infusions are only partly successful in improving symptoms and probably do not prolong survival in patients with severe congestive heart failure. Administration of this form of therapy on a clinical basis should be undertaken cautiously until safety and efficacy are demonstrated in prospective, controlled trials.

Early reperfusion therapy improves left ventricular function after acute inferior myocardial infarction associated with right coronary artery disease.

Quantitative global and regional ventriculographic analysis was performed acutely and 1 week later in 46 patients undergoing reperfusion procedures within 6 hours of acute inferior myocardial infarction due to right coronary artery disease. While serial improvement in global left ventricular ejection fraction was not demonstrated for the group, infarct zone regional wall motion did improve (-2.7 +/- 0.9 vs -2.3 +/- 1.4 SD/chord, p less than 0.007). Serial improvement in global ejection fraction was demonstrated in the subgroup of patients treated within 2 hours of symptom onset (55 +/- 10 vs 62 +/- 10%; n = 5; p less than 0.03). Infarct zone regional wall motion improved serially only in the subgroup of patients treated within 3 hours of symptom onset (-2.4 +/- 1.1 vs -1.3 +/- 1.7 SD/chord; n = 11; p less than 0.007). Patients with initially patent arteries had a higher ejection fraction on follow-up catheterization than did those with initially occluded vessels (61 +/- 11 vs 55 +/- 7%; p less than 0.02), and patients with patent arteries at follow-up had a higher ejection fraction than did those whose arteries were occluded (60 +/- 9 vs 48 +/- 4%; p less than 0.0001). We conclude that significant improvement in global and regional left ventricular function in patients with inferior myocardial infarction is possible when reperfusion therapy is begun early or when arterial patency is achieved.