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Biomedical subjects

A M Ross

Publications and source records attributed to A M Ross.

At least 55 records · Page 3Linked to original sources
PubMed1996

The role of oak pollen in hay fever consultations in general practice and the factors influencing patients' decisions to consult.

BACKGROUND: Patients often consult for hay fever before significant counts of grass pollen are recorded, and this has prompted the question, 'Are symptoms already present or are patients consulting to obtain medication in anticipation?' AIM: The study is concerned with the relationship between hay fever symptoms and pollens, and also with the impact of the media on patient consulting behaviour. METHOD: Symptom questionnaires were presented to patients consulting with hay fever for the first time that year in 1994 in four Birmingham practices. The questionnaire concerned the nature and duration of symptoms and the influence of the media on their decision to consult. Incidence data collected over the spring and summer periods (1989-1995) in the Weekly Returns Service (WRS) were examined in relation to pollen counts reported by the Midlands Asthma and Allergy Research Association at Derby. Data are presented for oak, birch and grass pollen, but other pollen data including rape, nettle and other trees were also examined. RESULTS: Questionnaire data from 1994 were analysed in two periods starting from 4 April: early (day 1-60) and late (day 61-124). Out of the 364 subjects, 38% consulted in the early period and 62% in the late period. Altogether, 41% developed symptoms before the start of the grass pollen season. Overall, 91% of patients first consulting in the early period had already experienced symptoms compared with 99% late period and were not simply collecting prescriptions in anticipation. The influence of the media on consultation behaviour was very small, except in children, 23% of whom (or their parents) were reported to be influenced. The new episode data from the WRS examined over 7 years showed an early peak that was coterminous with oak pollen, and a later and higher peak with grass pollen. CONCLUSION: The consistency of the relationship between oak pollen and the early peak of hay fever over the years examined suggests that oak pollen is a major cause of hay fever symptoms.

Adolescent↗
PubMed1995

Early and 1-year clinical outcome of patients' evolving non-Q-wave versus Q-wave myocardial infarction after thrombolysis. Results from The TIMI II Study.

BACKGROUND: There are few data comparing clinical outcome and potential indications for routine post-myocardial infarction cardiac catheterization and revascularization of patients who sustain a non-Q-wave versus Q-wave infarct after thrombolytic therapy. METHODS AND RESULTS: A secondary analysis of 2634 patients enrolled in the TIMI II trial with a first myocardial infarction was performed to determine 6-week and 1-year cardiac event rates and identify clinical and angiographic differences between the 1867 patients (70.9%) who evolved a Q-wave infarct and the 767 patients (29.1%) who sustained a non-Q-wave infarct after treatment with intravenous thrombolytic therapy. Male sex (85.3% versus 75.6%; P < .001) and anterior wall infarcts (53.8% versus 43.7%; P < .001) were more frequent in the Q-wave versus the non-Q-wave group. During recombinant tissue-type plasminogen activator (rTPA) infusion, a greater percentage of non-Q-wave patients (37.3% versus 23.5%; P = .001) had normalization of initial ST-segment elevation. Infarct-related artery patency (TIMI flow grade 2 or 3) (P = .02), complete infarct-related artery reperfusion (TIMI 3 flow grade) (P < .001), and the percentage of patients with a predischarge resting left ventricular ejection fraction > 55% (P < .001) were greater in the non-Q-wave group. New congestive heart failure during hospitalization developed more frequently in Q-wave patients (18.9% versus 11.6%; P < .001). After 42 days, the occurrences of reinfarction (P = .76), death (P = .76), and combined death or reinfarction (P = .43) were similar in patients assigned to the invasive or conservative postlytic management strategy, regardless of infarct type. One-year mortality was 3.4% versus 4.4% for non-Q-wave versus Q-wave infarct type, respectively (P = .25). CONCLUSIONS: Angiographic and clinical differences were observed between patients who present with initial ST-segment elevation and evolve early non-Q-wave versus Q-wave myocardial infarcts after treatment with rTPA, heparin, and aspirin. Early mortality and adverse clinical cardiac events in these patients are not significantly different after a conservative compared with an invasive treatment strategy, regardless of whether the infarct type is non-Q wave or Q wave.

Angioplasty, Balloon, Coronary↗
PubMed1995

Doppler guide wire flow-velocity indexes measured distal to coronary stenoses associated with reversible thallium perfusion defects.

A Doppler guide wire was used to measure phasic coronary blood flow velocity distal to coronary stenoses in 17 symptomatic patients with corresponding positive exercise or adenosine thallium scintigrams. Distal average peak velocity and diastolic/systolic flow-velocity ratio were obtained in 16 vessels with stenoses (55% to 85% diameter stenosis) and a corresponding reversible thallium defect and in 11 control vessels with no stenosis or thallium defect. Coronary flow-velocity reserve was obtained with intracoronary adenosine. Coronary flow reserve (2.3 +/- 0.4 vs 1.2 +/- 0.3, p < 0.01) and diastolic/systolic flow-velocity ratio (1.95 +/- 0.56 vs 1.44 +/- 0.59, p < 0.04) were significantly different between normal vessels and distal to stenoses, respectively. Excellent concordance between distal coronary flow reserve and diastolic/systolic flow-velocity ratio to thallium scintigraphy was noted. A coronary flow reserve of < 1.8 and a diastolic/systolic flow-velocity ratio of < 1.7 predicted a reversible thallium perfusion scintigram (concordance 96% and 88%, respectively). Distal coronary flow velocity indexes may provide an alternative means of physiologic assessment of lesion severity during coronary angiography.

Adenosine↗
PubMed1995

Coronary artery bypass graft surgery after thrombolytic therapy in the Thrombolysis in Myocardial Infarction Trial, Phase II (TIMI II).

OBJECTIVES: We examined the results of coronary artery bypass graft surgery after thrombolytic therapy in the Thrombolysis in Myocardial Infarction trial, Phase II (TIMI II) with particular emphasis on patient characteristics, the impact of antecedent percutaneous transluminal coronary angioplasty and morbidity and mortality in certain subgroups. BACKGROUND: Coronary bypass surgery is frequently used after thrombolytic therapy, but there is relatively little information with regard to early and late outcomes. METHODS: We analyzed 3,339 patients enrolled in the TIMI II trial. Bypass surgery was performed in 390 patients (11.7%): 54 (14%) within 24 h after entry into the trial or within 24 h of coronary angioplasty and 336 (86%) between 24 h and 42 days after entry. RESULTS: Perioperative mortality rates were, respectively, 16.7% and 3.9% (p < 0.001); perioperative myocardial infarction rates were 5.6% and 6.2%, respectively; and major hemorrhagic events occurred in 74% and 50.9%, respectively (p = 0.002). On multivariate analysis, the only independent predictor of perioperative mortality was bypass surgery within 24 h after entry or after coronary angioplasty. Among patients undergoing bypass surgery within 24 h of entry or after coronary angioplasty, the prevalence of multivessel disease (59.1% vs. 77.8%) and use of the internal thoracic artery (18.5% vs. 62.5%) were lower than in the remaining surgical patients. Among the 322 perioperative survivors, the 1-year mortality rate after discharge was only 2.2% and 1.9%, respectively, in the two groups. Only one patient had a documented recurrent myocardial infarction during the first year. CONCLUSIONS: The increased mortality rate with bypass surgery after thrombolytic therapy, particularly in patients undergoing operation within 24 h of coronary angioplasty or during the involving phase of infarction, must be balanced against the excellent 1-year prognosis and perioperative survivors, who are in general a group at higher risk of death or recurrent infarction. These data provide a basis for comparison for future studies.

Angioplasty, Balloon, Coronary↗
PubMed1994

Incidence of allergic rhinitis in general practice, 1981-92.

OBJECTIVES: To determine the epidemiology of hay fever and to consider the role of pollution. DESIGN: Examination of data on weekly incidence of allergic rhinitis and hay fever by age, sex, region, and location. SETTING: Royal College of General Practitioners Weekly Returns Service. Practice data were based on registered populations of 220,000 in 1981, rising to 700,000 in 1992 from England and Wales. MAIN OUTCOME MEASURES: Numbers of new cases of hay fever and allergic rhinitis. Data on pollen counts for Darlington, Derby, and London. RESULTS: The incidence of allergic rhinitis fluctuated greatly from year to year but showed no trend. Peaks in hay fever coincided with peak pollen counts. No important differences were found between urban and rural locations or different parts of the country with respect to both size and timing of the peaks. Incidence was highest in children (5-14 years). CONCLUSIONS: The similarity of the results throughout England and Wales does not support an important role for local pollutants in hay fever. However, the possibility that levels of pollutants are high enough to act as an adjuvant in hay fever across the whole study area has not been excluded.

Adolescent↗
PubMed1994

Bedside monitoring of heparin therapy: comparison of activated clotting time to activated partial thromboplastin time.

Heparin anticoagulation is utilized during and after interventional cardiac catheterization procedures to reduce the risk of acute thrombotic coronary artery occlusion. The short half-life of heparin, the importance of maintaining therapeutic anticoagulation, and the time delay inherent in the processing and retrieval of the activated partial thromboplastin time (aPTT) by the hospital laboratory has generated interest in point-of-care heparin monitoring. The activated clotting time (ACT), the aPTT as assessed by both a new portable device, as well as the hospital laboratory, and heparin levels (H) were obtained from the same sample of blood in 100 patients receiving intravenous heparin. There was an excellent correlation between the aPTT determined at the bedside and by the hospital laboratory (r = .89). The ACT did not correlate well with either the laboratory or bedside aPTT (r = .63, .68 respectively). In the sub-therapeutic and therapeutic range, there was essentially no correlation between ACT and H. Only ACT values > 225 sec were predictive of therapeutic or supra-therapeutic aPTTs. ACT values < 225 sec, however, were not useful in predicting degree of anticoagulation. In situations in which the maintenance of therapeutic anticoagulation is critical as well as those in which the determination of lack of anticoagulation is required, the bedside determination of aPTT appears to be a useful tool.

Cardiac Catheterization↗
PubMed1994

Mortality within 24 hours of thrombolysis for myocardial infarction. The importance of early reperfusion. The GUSTO Investigators, Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries.

BACKGROUND: A paradoxical increased risk of death has been reported during the first 24 hours after thrombolysis for myocardial infarction. The mechanism of this phenomenon is not known, nor is its relation to the success or failure of reperfusion. The present study was a prospectively designed analysis of deaths occurring within the first 24 hours in the GUSTO trial. METHODS AND RESULTS: There were 41,021 patients enrolled in GUSTO, a randomized comparison of streptokinase with intravenous or subcutaneous heparin, accelerated tissue-type plasminogen activator (TPA), and combination of streptokinase and TPA. An angiographic mechanistic substudy examined reperfusion (using the TIMI flow grading criteria) 90 minutes after the assigned thrombolytic regimen was begun in 1567 patients. There were 1125 deaths (2.8%) within 24 hours ("early deaths") and 1726 additional deaths (4.2%) after 24 hours but within 30 days ("later deaths"). At the time of presentation, the most potent predictors of early death were hypotension and sinus tachycardia. In a multiple logistic regression model, lower systolic blood pressure, shorter height, higher heart rate, and the absence of prior smoking distinguished early death from later death. Reinfarction occurred in 26 patients (2.4%), shock in 572 patients (52%), atrioventricular block in 308 patients (28%), and tamponade in 106 patients (10%) dying early compared with 262 (15%), 788 (46%), 396 (23%), and 74 (4%) respective patients dying later. There were no differences in early mortality among the thrombolytic regimens for the first 6 hours after randomization. By 24 hours, however, mortality was 2.89% for streptokinase recipients, 2.84% for combination therapy recipients, and 2.36% for accelerated TPA recipients (P = .005). There was little difference among patients with differing flow grades in the infarct artery during the first 4 hours, although mortality was 2.35% for patients with flow grade 0 or 1, 2.92% for patients with flow grade 2, and 0.89% for patients with flow grade 3. CONCLUSIONS: Even with aggressive management regimens, mortality within the first 24 hours accounted for a large proportion of postthrombolytic deaths. Patients dying early were more likely to present with pump failure than were those dying later and were more likely to diet of events related to left ventricular dysfunction, although cardiac tamponade also accounted for a significant minority of these deaths. Thus, the severity of the clinical presentation rather than the underlying risk factors predicts early mortality. Based on the angiographic substudy data, it appears that rather than hastening early mortality, successful restoration of complete antegrade flow in the infarct-related artery protects against early death.

Aged↗
PubMed1993

The current controversies regarding reperfusion therapy for acute myocardial infarction.

Despite impressive clinical advantages proven for reperfusion (thrombolytic) therapy in acute myocardial infarction, considerable controversy persists regarding patient selection, choice of fibrinolytics, adjunctive therapies, and the role of angioplasty. Accruing new information supports the understanding that only very early reperfusion substantially salvages jeopardized myocardium, but that by other mechanisms some regimens produce a mortality benefit when administered as late as 12 h after infarct onset. Evidence that fibrin selective plasminogen activators lyse coronary thrombi faster than systemic agents has expanded along with clinical trial data demonstrating a concomitant greater dependence on intense anticoagulation to maintain this speed of patency advantage. The clinical value of such strategies is still under evaluation (the "GUSTO" Trial). Newly reported comparisons of reperfusion by angioplasty suggest that in optimal circumstances this approach produces results comparable with thrombolytic therapy.

Angioplasty, Balloon, Coronary↗
PubMed1992

Heparin-induced prolongation of partial thromboplastin time after thrombolysis: relation to coronary artery patency. HART Investigators.

Having previously shown in the Heparin Aspirin Reperfusion Trial that the empiric use of early intravenous heparin after recombinant tissue-type plasminogen activator (rt-PA) is an important component in the overall treatment strategy, we examine in this report the specific relation between the degree of prolongation of activated partial thromboplastin time and coronary artery patency. To evaluate the hypothesis that arterial patency after administration of rt-PA for acute myocardial infarction is sustained by effective anticoagulation, activated partial thromboplastin time of heparin recipients was determined 8 and 12 h after the start of thrombolysis. Mean activated partial thromboplastin time was higher among patients with an open infarct-related artery than in those with a closed artery (81 +/- 4 vs. 54 +/- 9 s, p less than 0.02). Only 45% of patients with values less than 45 s at both 8 and 12 h had Thrombolysis in Myocardial Infarction (TIMI) flow grade 2 or 3 in the infarct-related artery at 18 h. In contrast, 88% of patients with activated partial thromboplastin time greater than 45 s and 95% of those with values greater than 60 s had an open infarct-related artery at 18 h (p = 0.003 and 0.0006, respectively). Among patients with an initially patent infarct-related artery who underwent repeat angiography at 7 days, activated partial thromboplastin time was similar in those with a persistently patent artery and those with late reocclusion. Excessive anticoagulation did not appear to increase hemorrhagic risk except that access site-related hemorrhage was more common in patients with activated partial thromboplastin time greater than 100 s at 8 h.(ABSTRACT TRUNCATED AT 250 WORDS)

Aspirin↗
PubMed1992

Anistreplase versus alteplase in acute myocardial infarction: comparative effects on left ventricular function, morbidity and 1-day coronary artery patency. The TEAM-3 Investigators.

OBJECTIVES: This double-blind, randomized, multicenter trial was designed to compare the effects of treatment with anistreplase (APSAC) and alteplase (rt-PA) on convalescent left ventricular function, morbidity and coronary artery patency at 1 day in patients with acute myocardial infarction. BACKGROUND: Anistreplase (APSAC) is a new, easily administered thrombolytic agent recently approved for treatment of acute myocardial infarction. Alteplase (rt-PA) is a rapidly acting, relatively fibrin-specific thrombolytic agent that is currently the most widely used agent in the United States. METHODS: Study entry requirements were age less than or equal to 75 years, symptom duration less than or equal to 4 h, ST segment elevation and no contraindications. The two study drugs, APSAC, 30 U/2 to 5 min, and rt-PA, 100 mg/3 h, were each given with aspirin (160 mg/day) and intravenous heparin. Prespecified end points were convalescent left ventricular function (rest/exercise), clinical morbidity and coronary artery patency at 1 day. A total of 325 patients were entered, stratified into groups with anterior (37%) or inferior or other (63%) acute myocardial infarction, randomized to receive APSAC or rt-PA and followed up for 1 month. RESULTS: At entry, patient characteristics in the two groups were balanced. Convalescent ejection fraction at the predischarge study averaged 51.3% in the APSAC group and 54.2% in the rt-PA group (p less than 0.05); at 1 month, ejection fraction averaged 50.2% versus 54.8%, respectively (p less than 0.01). In contrast, ejection fraction showed similar augmentation with exercise at 1 month after APSAC (+4.3% points) and rt-PA (+4.6% points), and exercise times were comparable. Coronary artery patency at 1 day was high and similar in both groups (APSAC 89%, rt-PA 86%). Mortality (APSAC 6.2%, rt-PA 7.9%) and the incidence of other serious clinical events, including stroke, ventricular tachycardia, ventricular fibrillation, heart failure within 1 month, recurrent ischemia and reinfarction were comparable in the two groups; and mechanical interventions were applied with equal frequency. A combined clinical morbidity index was determined and showed a comparable overall outcome for the two treatments. CONCLUSIONS: Convalescent rest ejection fraction was high after both therapies but higher after rt-PA; other clinical outcomes, including exercise function, morbidity index, and 1-day coronary artery patency, were favorable and comparable after APSAC and rt-PA.

Anistreplase↗
PubMed1992

Prognosticators of outcome after major head injury in the elderly.

In 195 elderly head-injured patients, Glasgow Coma Scale (GCS) scores (admission and 72 hours) and intracranial pressure (ICP) 0-12 days after injury were compared to 6 month Glasgow Outcome Scores. All patients remaining comatose at least 72 hours after injury died within 6 months. The mortality rate among patients with ICP greater than 20 mm Hg was higher both at 72 hours and at 6 months after injury. The 6 month mortality rate was 75% overall and 90% among patients with elevated ICP. This increased mortality in elderly patients with initially elevated ICP indicates that nurses and other health professionals should consider ICP as well as level of consciousness when counseling patients and families regarding the likely outcome after major head injuries.

Age Factors↗
PubMed1991

Importance of myocardial infarct artery patency on the prevalence of ventricular arrhythmia and late potentials after thrombolysis in acute myocardial infarction.

Sustained infarct artery patency is an important determinant of survival in patients with acute myocardial infarction. We studied 61 patients with acute myocardial infarction who received intravenous recombinant tissue-type plasminogen activator, aspirin or heparin within 6 hours of symptom onset, to determine if infarct artery patency after intravenous thrombolytic therapy influences myocardial electrical stability as measured by the prevalence of spontaneous ventricular ectopy or late potential activity. Infarct artery patency was determined by angiographic evaluation 2.5 +/- 3 days after infarction. Forty-eight patients (79%) had a patent infarct-related artery and 13 (21%) patients had an occluded vessel. The mean number of ventricular premature complexes (VPCs)/hour (p less than 0.01) and the prevalence of late potentials (54 vs 19%; p less than 0.03) were significantly higher in patients with an occluded versus patent-infarct related vessel. Although VPC frequency and late potentials were not influenced by the time to thrombolytic treatment, patients with a patent infarct-related artery had a lower prevalence of late potentials regardless of whether treatment was initiated less than or equal to 2 hours (25% patent vs 50% occluded; p = not significant) or 2 to 6 hours (16% patent vs 55% occluded; p greater than 0.03) after symptom onset. Thus, successful thrombolysis decreases the frequency of ventricular ectopic activity and late potentials in the early postinfarction phase. The reduction in both markers of electrical instability may help explain why the prognosis after successful thrombolysis is improved after acute myocardial infarction.

Aged↗
PubMed1991

Cardiac myocytes and dendritic cells harbor human immunodeficiency virus in infected patients with and without cardiac dysfunction: detection by multiplex, nested, polymerase chain reaction in individually microdissected cells from right ventricular endomyocardial biopsy tissue.

Two hundred fifteen patients infected with human immunodeficiency virus (HIV) participated in a prospective longitudinal study of HIV-related heart disease. Evaluation included signal-averaged electrocardiography and echocardiography. Fifteen patients underwent endomyocardial biopsy, 5 had cardiovascular symptoms and 10 did not. Cardiac myocytes or dendritic cells were prepared by individual cell microdissection to sort them from other cell types such as interstitial cells or circulating blood elements. HIV proviral sequences were amplified in samples of 15 to 20 cells of each type by multiplex, nested, polymerase chain reaction and hybridized to 32P-labeled probes specific for regions within the gag and pol genes of HIV-1. The results showed the presence of HIV sequences in myocytes of 2 of 5 patients with cardiac symptoms and in 6 of 10 without. Thus, symptomatic HIV cardiomyopathy did not appear to be a direct consequence of the virus on myocardial cells. In dendritic cells, HIV sequences were detected in 5 of 5 patients with cardiac symptoms and in 8 of 10 with apparently normal ventricular function. Furthermore, dendritic cells were somewhat more numerous in the myocardium of symptomatic than asymptomatic patients. Our studies are the first to directly detect the HIV genome in purified cardiac myocytes from patients with and without cardiac dysfunction. Our findings do not support a direct role of the virus in myocardial dysfunction. However, the results do suggest that the interstitial dendritic cells may be involved in some manner in the development of cardiac dysfunction observed in HIV-infected patients.

Adult↗