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Biomedical subjects

K A Fox

Publications and source records attributed to K A Fox.

At least 109 records · Page 6Linked to original sources
PubMed1994

Hyperinsulinaemia in ischaemic heart disease: the importance of myocardial infarction and left ventricular function.

Elevated circulating insulin levels have been reported in ischaemic heart disease, and may be of aetiological importance. Previous studies have not considered the potential influence of heart failure or of previous myocardial infarction, as opposed to stable angina. We therefore measured the insulin response to a 75 g oral glucose tolerance test in five groups with normal glucose tolerance, comparing normal male controls to men with chronic stable angina, men with recent myocardial infarction (two groups, 3 weeks and 3 months post infarction), and men with chronic severe heart failure. Only patients with chronic heart failure had fasting hyperinsulinaemia, probably reflecting associated neuroendocrine abnormalities. Stimulated hyperinsulinaemia was present in all patient groups, but was less pronounced and of shorter duration in patients with angina. At 120 min, only patients with heart failure or previous myocardial infarction were hyperinsulinaemic. The degree of stimulated hyperinsulinaemia was not influenced by the presence of heart failure or by the length of time from infarction. Hyperinsulinaemia is associated with impaired peripheral muscle glucose uptake and metabolism, and might contribute to muscular fatigue on exertion in patients with previous myocardial infarction or heart failure.

Administration, Oral↗
PubMed1993

Radiation therapy salvage of Hodgkin's disease following chemotherapy failure.

PURPOSE: This study evaluates the efficacy of comprehensive salvage radiation therapy, with or without chemotherapy, in selected patients with Hodgkin's disease who have failed primary combination chemotherapy. METHODS AND MATERIALS: Between 1972 and 1991, 28 patients with advanced Hodgkin's disease failing intensive combination chemotherapy in previously unirradiated nodal and/or pulmonary sites were treated with salvage radiotherapy with curative intent. Treatment consisted of comprehensive extended field radiotherapy to all known areas of disease. Total radiation doses ranged from 17.0 to 50.0 Gy, with only five patients (18%) receiving < 30.0 Gy to any field. Twelve patients also received chemotherapy as part of their salvage regimen. RESULTS: Twenty-six patients (93%) achieved a complete response and 14 (50%) remain in continuous complete remission at 14 to 133 months. In addition, three patients (11%) who failed salvage radiotherapy are now without evidence of disease following additional therapy. With a median follow-up of 47 months (range 14+ to 198+), actuarial median relapse-free survival and overall survival are 46 and 97 months, respectively. Actuarial 5-year relapse-free survival and overall survival are 40% and 63%, respectively. Patients with an initial complete response to chemotherapy had a significantly longer actuarial relapse-free survival than those with an initial partial response (p = 0.02). Salvage therapy was generally well-tolerated and resulted in no treatment-related deaths. CONCLUSION: Comprehensive salvage radiotherapy is of significant benefit in selected patients and should be considered an option for patients with advanced Hodgkin's disease following chemotherapy failure.

Adolescent↗
PubMed1993

Prospective comparison of unstable angina versus non-Q wave myocardial infarction during antithrombotic therapy. Antithrombotic Therapy in Acute Coronary Syndromes Research Group.

OBJECTIVES: This study was designed to compare the response of unstable angina and non-Q wave myocardial infarction during treatment with antithrombotic therapy. BACKGROUND: Antithrombotic therapy is beneficial in patients with these two coronary syndromes. METHODS: In a multicenter trial of antithrombotic therapy in unstable angina or non-Q wave myocardial infarction, 358 patients admitted within 48 h of chest pain were randomized to antithrombotic therapy with either 1) aspirin alone, or 2) aspirin plus heparin followed by aspirin plus warfarin, and were prospectively followed up for 12 weeks. Admission cardiac enzyme analyses revealed unstable angina in 268 patients and non-Q wave myocardial infarction in 62. Given an event rate of about 25%, this study has a power of 80% to detect a 50% difference between the two groups. RESULTS: Patients with unstable angina and non-Q wave myocardial infarction were similar with regard to age, gender, coronary risk factors and prior antianginal medication. Primary end points at 12 weeks were recurrent ischemia, infarction and death. [table: see text] In the non-Q wave group, all infarctions and death occurred within the 1st week. CONCLUSIONS: Patients with unstable angina or non-Q wave myocardial infarction on antithrombotic therapy have a similar total number of ischemic events by 12 weeks. However, despite maximal medical therapy with antianginal and antithrombotic medication, patients with non-Q wave infarction have a significantly higher rate of reinfarction and death.

Adrenergic beta-Antagonists↗
PubMed1993

Propranolol and lidocaine inhibit neural norepinephrine release in hearts with increased extracellular potassium and ischemia.

BACKGROUND: Propranolol and lidocaine are effective antiarrhythmic drugs in myocardial ischemia and infarction. As sympathetic nerve activation and norepinephrine release in ischemic hearts are arrhythmogenic, we tested the possibility that both agents inhibit neural norepinephrine release following sympathetic activation in the ischemic environment. METHODS AND RESULTS: The model used was an in situ perfused innervated rat heart. Norepinephrine release was induced by electrical stimulation of the left cervicothoracic stellate ganglion and analyzed using radioenzymatic assay or high-performance liquid chromatography. In normoxically perfused hearts, evoked norepinephrine release was not affected by either of the two agents at doses of 1 to 10 mumol/L when extracellular K+ concentration was 4 mmol/L but dose-dependently reduced at 10 mmol/L K+ (D,L-propranolol: -53 +/- 4% at 1 mumol/L and -64 +/- 6% at 10 mumol/L K+, lidocaine: -37 +/- 11% at 0.1 mumol/L, -67 +/- 5% at 1 mumol/L, and -75 +/- 6% at 10 mumol/L). At 10 mmol/L K+, norepinephrine release was not affected by timolol or atenolol (both 10 mumol/L but was equally inhibited by D- or L-propranolol at 10 mumol/L (-56 +/- 5% and -53 +/- 9%, respectively), indicating a beta-blocking-independent mechanism. In hearts with metabolic acidosis (pH 6.85) at K+ of 4 mmol/L, neural norepinephrine release was also reduced by propranolol at 10 mumol/L (-37%). Finally, in hearts perfused with 4 mmol/L K+ and subjected to 6-minute periods of ischemia, neural norepinephrine release was similarly suppressed by D,L-propranolol (-38 +/- 6% at 0.1 mumol/L, -44 +/- 5% at 1 mumol/L, and -78 +/- 3% at 10 mumol/L) or lidocaine (-39 +/- 7% at 0.1 mumol/L, -58 +/- 9% at 1 mumol/L, and -91 +/- 3% at 10 mumol/L). CONCLUSIONS: These data indicate that propranolol and lidocaine inhibit neural norepinephrine release via a Na+ channel-blocking mechanism that is synergistic with changes induced by ischemia, primarily raised extracellular K+. This mechanism may contribute to the anti-ischemic and antiarrhythmic properties of both agents in acute myocardial ischemia, which induces increased extracellular K+ and sympathetic activation.

Animals↗
PubMed1992

Effect of "fast track" admission for acute myocardial infarction on delay to thrombolysis.

OBJECTIVE: To evaluate the impact of a fast track triage system for patients with acute myocardial infarction. DESIGN: Comparison of delays in admission to hospital and in receiving thrombolytic treatment before and after introducing fast track system with delays recorded in 1987-8. Patients fulfilling clinical and electrocardiographic criteria for myocardial infarction were selected for rapid access to the cardiac care team, bypassing evaluation by the medical registrar. SETTING: Major accident and emergency, cardiac and trauma centre. SUBJECTS: 359 patients admitted to the cardiac care unit during 1 February to 31 July 1990 with suspected acute infarction. MAIN OUTCOME MEASURES: Accuracy of diagnosis and delay from arrival at hospital to thrombolytic treatment. RESULTS: 248 of the 359 patients had myocardial infarction confirmed, of whom 127 received thrombolytic treatment. The fast track system correctly identified 79 out of 127 (62%) patients who subsequently required thrombolytic treatment. 95% (79/83) of patients treated with thrombolysis after fast track admission had the diagnosis confirmed by electrocardiography and enzyme analysis. The median delay from hospital admission to thrombolytic treatment fell from 93 minutes in 1987-8 to 49 minutes in fast track patients (p less than 0.001). Delay in admission to the cardiac care unit was reduced by 47% for fast tract patients (median 60 minutes in 1987-8 v 32 minutes in 1990, p less than 0.001) and by 25% for all patients (60 minutes v 45 minutes, p less than 0.001). CONCLUSION: This fast track system requires no additional staff or equipment, and it halves inhospital delay to thrombolytic treatment without affecting the accuracy of diagnosis among patients requiring thrombolysis.

Aged↗
PubMed1992

Anomalous origin of the right coronary artery from the pulmonary artery in association with congenital aneurysm of the sinus of Valsalva: angiographic diagnosis of a rare association.

A 37 year old man presenting with acute heart failure, hypotension, and acute renal failure was diagnosed by cardiac catheterisation and angiography to have the rare combination of congenital aneurysm of the non-coronary sinus of Valsalva rupturing into the right ventricle, and an anomalous origin of the right coronary artery from the main pulmonary artery. The diagnosis could not be confirmed by transthoracic echocardiography in this patient. This combination of defects, confirmed at cardiac surgery, has not been reported before, and this case report highlights the importance of preoperative definition of congenital defects associated with an aneurysm of the sinus of Valsalva.

Acute Kidney Injury↗
PubMed1991

Comparative analysis of long-term mortality after thrombolytic therapy.

In patients with acute myocardial infarction, thrombolytic therapy has a demonstrable and favorable impact on a range of clinical indicators, including left ventricular function, infarct size, coronary arterial patency, and symptom relief. However, these indicators have not provided a reliable basis for the comparison of thrombolytic regimens; mortality provides the "gold standard." One-year mortality obviates the differences in the timing of short-term comparisons (in-hospital, 30-day, or 5-week). In addition, late effects of differences in patency, including the impact of reocclusion, infarct healing, and remodeling, will be evident by 1 year. Meta-analysis of data from previous major mortality studies shows that differences in design and the overlap of confidence intervals of mortality studies suggest that no thrombolytic agent is superior in terms of short-term mortality. Long-term survival may provide a more meaningful basis for comparison of efficacy of the thrombolytic regimens. Long-term mortality has been evaluated for anistreplase in acute myocardial infarction in a composite analysis, similar to a meta-analysis. From the pooled life table analysis of all anistreplase studies, the odds reduction in mortality at 1 year was approximately 48%.

Fibrinolytic Agents↗
PubMed1991

Evaluation of drug information for cardiology patients.

1. Cardiologists and pharmacists at the University Hospital of Wales collaborated to write 20 individual leaflets incorporating guidelines for a range of drugs used in the treatment of cardiology patients. The Plain English Campaign advised on the intelligibility and presentation of the information. 2. One hundred and twenty-five patients from the Regional Cardiology Unit, University Hospital of Wales were randomly allocated to receive usual verbal counselling about their drug treatment with or without an individualised drug information wallet. Two weeks after discharge from hospital patients completed a postal questionnaire to determine their satisfaction with the information about their drug treatment and their understanding of it. Forty-nine questionnaires were returned from the leaflet group and 52 from the control group. 3. The provision of written guidelines resulted in significant improvements in patients' satisfaction with their drug treatment (chi 2 = 33.3, P less than 0.001) and their understanding of it (P less than 0.001, Mann-Whitney test). Overall, patients who received leaflets were more likely to be aware of the potential side effects of their drugs but less likely to be apprehensive about them. Succinct guidelines concerning drug therapy can be assimilated by cardiology patients and provide them with a permanent record for future reference.

Adult↗
PubMed1991

Pre-hospital thrombolysis: current status and future prospects.

The impact of thrombolytic therapy in acute myocardial infarction has been such that it now constitutes standard therapy for patients who present to hospital with acute myocardial infarction. In an attempt to minimise the duration of ischaemia, and subsequent impairment of contractile function, trials of pre-hospital thrombolysis have been initiated. These reveal time gains of up to 60 minutes but convincing evidence of clinical benefit has not yet been forthcoming. This review examines the rationale for very early thrombolysis, in the context of the underlying pathophysiological mechanisms. It examines the impact of recent small scale studies on coronary patency, left ventricular function and infarct size and examines the potential risks. Large scale studies of pre-hospital thrombolysis are in progress and their findings will need to be interpreted in comparison with optimal 'fast-track' in-hospital treatment. The review highlights the need for co-ordinated policies for acute management of myocardial infarction involving primary care, the emergency medical systems and cardiac units. Enthusiasm for wide scale administration of thrombolytics by general practitioners, without electrocardiographic confirmation of the diagnosis, must be tempered by a clear analysis of the potential risks and benefits. Current evidence does not support such widespread clinical application, outwith the current evaluation studies. An urgent re-evaluation of hospital triage of patients with acute myocardial infarction is merited.

Emergency Medical Services↗
PubMed1990

Long-term cardiorespiratory effects of amelioration of renal anaemia by erythropoietin.

The long-term cardiorespiratory effects of recombinant human erythropoietin treatment were investigated in ten haemodialysis patients by means of maximum exercise testing, lung function tests, echocardiography, chest X-ray, and rheological assessment over 12 months. There were significant rises in exercise time (mean [SD] 13.2 [5.5] to 20.0 [6.2] min), maximum oxygen consumption (19.1 [7.0] to 25.0 [6.7] ml.min-1.kg-1), and anaerobic threshold (11.7 [3.6] to 15.4 [4.8] ml.min-1.kg-1) after 2 months of erythropoietin treatment. The improvements were maintained but not augmented on repeat testing after 4, 8, and 12 months of therapy. Carbon monoxide transfer [corrected] rose from 15.5 (2.9) to 18.6 (3.7) ml.min-1.mm Hg-1. There was a substantial reduction in exercise-induced cardiac ischaemia (eight patients had significant ST segment depression before erythropoietin, only one after 2 months' treatment, and none after 12 months' treatment), despite a significant rise in whole blood viscosity. Left ventricular mass, as estimated by echocardiography, progressively decreased from 354 (169) g to 251 (95) g after 12 months' treatment, and four patients showed a reduction in cardiothoracic ratio on chest X-ray.

Adult↗
PubMed1990

The safety of anistreplase from the placebo-controlled AIMS study (anistreplase Intervention Mortality Study). The AIMS Study Group.

In the anistreplase, or anisoylated plasminogen streptokinase activator complex (APSAC) Intervention Mortality Study (AIMS), 1,258 patients with acute myocardial infarction were randomized in a parallel, double-blind, placebo-controlled mortality study in which they received either anistreplase or placebo, followed by anticoagulation therapy. Data on all adverse clinical events were recorded, regardless of their clinical significance or possible relation to therapy. There was a similar frequency of such events in both groups (anistreplase 80.4%, placebo 76.0%, difference not significant). Cardiovascular events included more reports of bradycardia, idioventricular rhythm, and hypotension in the anistreplase group, and a higher incidence of cardiac arrest, ventricular fibrillation, complete heart block, and pericarditis in the placebo group. Hemorrhagic events occurred in 13.8% of patients in the anistreplase group compared with 4.1% of patients in the placebo group. Most of these events consisted of bleeding or bruising around the puncture sites. There was a low incidence of allergic events after administration of both anistreplase and placebo. Thirteen cerebrovascular events (8 strokes and 5 transient ischemic episodes) were reported in the anistreplase group, compared with 5 in the placebo group (5 and 0, respectively). The mean systolic and diastolic pressures were significantly lower (by 5-10 mmHg) in patients in the anistreplase group during the first 24 hours after dosing. There were no significant differences in temperature and pulse rate between the two groups. The incidence of chest pain during the first 4- to 24-h period was lower in the anistreplase-treated patients than in the placebo group. The frequency of in-hospital reinfarction was higher in anistreplase-treated patients compared with patients given placebo.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗