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Biomedical subjects

J Barry

Publications and source records attributed to J Barry.

At least 19 recordsLinked to original sources
PubMed1992

Detection and significance of intraoperative and postoperative myocardial ischemia in peripheral vascular surgery.

OBJECTIVE: To determine the incidence and significance of intraoperative and postoperative myocardial ischemia and their relationship to preoperative ischemia and postoperative cardiac events in patients undergoing peripheral arterial surgery. DESIGN: Prospective cohort trial. PATIENTS: One hundred fifteen patients undergoing elective vascular surgery who met predefined eligibility criteria and were thought to have acceptable cardiac risk as assessed by independent cardiologists. INTERVENTIONS: Ambulatory electrocardiographic monitoring preoperatively, intraoperatively, and up to 72 hours postoperatively. MEASUREMENTS: Preoperative clinical characteristics and laboratory data were collected. Predefined adverse cardiac events were identified by an investigator who was "blinded" to monitoring results. Monitor recordings were interpreted for ST-segment depression by investigators blinded to patient information. MAIN RESULTS: Intraoperative ischemia was present in 21 patients (18%), and postoperative ischemia was present in 35 (30%). There were 16 postoperative cardiac events. The relative risk of suffering a cardiac event was 2.7 in patients with intraoperative ischemia and was 16 in patients with postoperative ischemia. Preoperative ischemia closely correlated with intraoperative and postoperative ischemia. Preoperative and postoperative ischemia preceded cardiac events in 14 of 16 patients. CONCLUSIONS: Preoperative ischemia appears to identify high-risk patients, and subsequent perioperative monitoring detects silent ischemia that commonly precedes clinical events and that may be treatable with anti-ischemia therapy.

Adult↗
PubMed1992

"Avoidable mortality" as an index of health care outcome: results from the European Community Atlas of "Avoidable Death".

The history of the European Community Atlas of "Avoidable Death" is given. Data from the second Atlas are presented. For all causes of death except asthma there was a decrease in mortality in the period 1980-1984 with respect to 1974-1978. Taking the EC as a whole as the standard (100) population the standardised mortality ratio (SMR) in Ireland in the period 1980-1984 for tuberculosis was 160, for asthma 180 and maternal mortality 58. Ireland had the highest mortality for tuberculosis in both time periods. Asthma mortality increased in all countries except Scotland between 1974-1978 and 1980-1984. Ireland had one of the highest declines in maternal mortality over the two time periods. Within Ireland tuberculosis mortality was highest in the Mid-Western Health Board and lowest in the North-Western Health Board. Asthma mortality was highest in the Western Health Board and lowest in the Mid-Western Health Board. Maternal mortality was highest in the Midland Health board and lowest in the Southern Health Board.

Adolescent↗
PubMed1992

Words and actions: a study in nurse wastage.

This paper examines whether a group of nurses' stated intentions to leave were subsequently transformed into actual leaving actions. We argue that establishing the truth of relationships between words and actions is of fundamental importance in social science research. Nurses broadly did what they said they would do. Hence, definite intentions to leave were generally acted upon while less strong leaving intentions were not acted upon to any practically significant degree. We further investigate the link between the nurses' words and actions by reporting on a small interview study where nurses were asked why they did or did not do as they stated. The importance of these findings in terms of health authorities planning their labour force is discussed.

Attitude of Health Personnel↗
PubMed1991

Waking and rising at night as a trigger of myocardial ischemia.

A diurnal pattern of changes in transient myocardial ischemia has been well documented in patients with coronary artery disease (CAD) with an increase in the early morning hours. To further investigate potential triggers of ischemia, certain defined and distinct episodes of waking and rising during the nighttime were examined. Of 113 patients who underwent ambulatory monitoring of the electrocardiogram, 466 episodes of ischemia lasting 3,926 minutes were detected in 67 of the patients. In 30 patients who had ischemia at night, 21 reported 36 occasions of waking and rising, and 67% of these events were associated with ST-segment depression. Frequency and duration of ischemia were similar in the nocturnal episodes versus the early morning episodes of ischemia as were the increases in heart rate at 30, 10, 5 and 1 minute before the onset. Even before waking, there was an increase in heart rate beginning approximately 30 minutes before the onset of ischemia. This increase became significant 5 minutes before onset both in the early morning and on rising at night. Patients with nocturnal ischemia had significantly worse clinical signs of CAD. This study shows that rising at night is often associated with episodes of myocardial ischemia and, like the morning events on rising, is likely an important trigger of ischemia in patients with CAD.

Adult↗
PubMed1991

Nursing: just a job? Do statistics tell us what we think?

This study considers the value of classifying attitudinal statements given by nurses in a questionnaire by the statistical procedure of latent class analysis. It demonstrates with the use of qualitative data derived from in-depth interviews how precarious are the groups derived from statistical analysis. However, it is argued that the apparent discrepancies between responses 'objectively' derived by a statistical approach and those 'subjectively' declared by respondents may focus on different levels of meaning and may well provide a useful resource. Most importantly, it is stressed that a dynamic model is needed which recognizes change and the consequences of change.

Attitude of Health Personnel↗
PubMed1991

Relations between heart rate, ischemia, and drug therapy during daily life in patients with coronary artery disease.

BACKGROUND: Previous studies have shown that little if any increase in heart rate occurs 1 minute before the onset of ischemia in ambulant patients with coronary artery disease. This study tested the hypothesis that there are characteristic relations between heart rate and ischemia in ambulant patients with coronary artery disease. METHODS AND RESULTS: Twenty-one patients with proven coronary disease demonstrated 212 episodes of ischemia during 504 hours of continuous monitoring of the electrocardiogram. An important increase in heart rate (from 74 +/- 11 to 90 +/- 14 beats/min, p less than 0.001) occurred between 5 and 30 minutes (not 1 minute) before the onset of ischemia. A significantly higher heart rate at onset of ischemia was seen during Bruce protocol exercise testing than during daily life (117 +/- 12 versus 95 +/- 15 beats/min, p less than 0.01). However, when a less-strenuous, but more prolonged, exercise protocol was used in a subgroup of patients (n = 12), ischemia occurred at a heart rate that was significantly lower than during the Bruce protocol (88 +/- 14 versus 103 +/- 15 beats/min, p less than 0.05) and was not significantly different from the threshold heart rate at onset of ischemia during daily life (88 +/- 14 versus 84 +/- 12 beats/min, p = NS). As part of two placebo-controlled trials, treatment with both propranolol and nitroglycerin altered the distribution of ischemic events by heart rate but in opposite directions. Although propranolol largely eliminated events occurring at high (greater than 100 beats/min) and moderate (80-100 beats/min) heart rates, the number of events at low (less than 80 beats/min) heart rates was increased. In contrast, nitroglycerin reduced episodes at low and moderate heart rates only. CONCLUSIONS: Important increases in heart rate occur before the onset of ischemia during daily life, but this increase occurs much earlier than has been reported. Duration of heart rate increase appears to influence the heart rate threshold for ischemia, and this may contribute to the occurrence of ischemia at lower heart rates during daily life than during standard exercise testing. Last, different classes of drugs appear to have characteristic effects on ischemia occurring at different heart rates that may be useful in planning therapy.

Activities of Daily Living↗
PubMed1991

Effects of asymptomatic ischemia on long-term prognosis in chronic stable coronary disease.

BACKGROUND: Ischemia on ambulatory electrocardiographic monitoring has been shown to adversely affect short-term prognoses in patients with unstable angina, after myocardial infarction, and with chronic stable angina. METHODS AND RESULTS: In this long-term study, we followed 138 patients (mean age, 59 +/- 9 years) with chronic stable angina and positive exercise tests for cardiac events (e.g. death, myocardial infarction, percutaneous transluminal coronary angioplasty, or coronary artery bypass graft surgery). In 105 patients, ambulatory electrocardiographic monitoring was performed after all antianginal medication was withheld for 48 hours. In 26 patients, the diagnostic tests were repeated while on their usual medication. In addition to the 105 patients, 33 patients had their monitoring performed only while on their usual medication. During 37 +/- 17 months of follow-up, there were nine deaths, nine myocardial infarctions, and 35 revascularization procedures. In patients monitored off medication, Cox survival analysis showed that the occurrence of ischemia on electrocardiographic monitoring was the most significant predictor of death and myocardial infarction in the subsequent 2 years (p = 0.02) and all adverse events for 5 years (p = 0.009). Patients who were monitored on medication and did not have ischemia (n = 18) appeared to have more adverse events than patients who had no ischemia while being monitored off medication (n = 43). CONCLUSIONS: Asymptomatic ischemia on ambulatory electrocardiographic monitoring in patients with stable angina predicts death and myocardial infarction for 2 years and all adverse events for 5 years. Monitoring performed while on medication may show no ischemia; however, this may not indicate low risk of future coronary events.

Actuarial Analysis↗
PubMed1990

Long-term prognosis of myocardial ischemia detected by Holter monitoring in peripheral vascular disease.

To assess the long-term prognostic significance of myocardial ischemia, as measured by ambulatory electrocardiographic monitoring, in patients with occlusive peripheral arterial disease, 176 eligible patients scheduled for elective peripheral arterial surgery at Brigham and Women's Hospital were prospectively studied. All patients were monitored preoperatively without alterations to baseline medications. Prospective follow-up was obtained during routine medical care as provided by blinded, independent physicians and by subsequent telephone contact with the patients. Thirty-two patients (18%) had a total of 75 episodes of myocardial ischemia, 73 (97%) of which were asymptomatic. During a mean follow-up period of 615 days, there were 9 cardiac deaths, 1 occurring in-hospital after peripheral vascular surgery, and 13 nonfatal myocardial infarctions, 4 occurring in-hospital after peripheral vascular surgery. Cardiac events occurred in 12 of 32 patients with ischemia (38%), including 6 cardiac deaths, and in 10 of 144 patients without ischemia (7%), including 3 cardiac deaths (risk ratio 5.4, 95% confidence interval 2.6 to 11.4). The sensitivity of ischemia was 55%, the specificity was 87%, the positive predictive value was 38%, and the negative predictive value was 93%. In a multivariate Cox proportional-hazards model controlling for age, gender, coronary risk factors, history of angina, myocardial infarction, coronary artery disease and antianginal medications, the presence of ischemia was the only independent predictor of outcome. In patients with peripheral arterial disease, who often are unable to perform adequate exercise testing, ambulatory monitoring for myocardial ischemia is a significant independent predictor of 1- to 2-year prognosis.

Adult↗
PubMed1990

Silent ischemia after myocardial infarction. Prognosis, mechanism, and intervention.

Asymptomatic ischemia after myocardial infarction is a common clinical problem. As much as 50% of the postinfarction patient population who have ischemia on exercise testing may have no symptoms at all. In these patients, ischemia detected by either exercise testing or ambulatory electrocardiographic monitoring, with or without symptoms, confers a worse prognosis. The mechanism of silent ischemia in this group of patients may be due to the deprivation of afferent innervations created by critically placed infarctions. The management of these postinfarction patients must be centered on the treatment of ischemia, regardless of symptoms.

Biomechanical Phenomena↗
PubMed1989

Enhancement of bacteriophage T4 late transcription by components of the T4 DNA replication apparatus.

The expression of the late genes in bacteriophage T4 development is closely connected to viral DNA replication. Three T4-encoded DNA polymerase accessory proteins are shown to stimulate transcription at T4 late promoters in an adenosine triphosphate (ATP) hydrolysis-requiring process. The properties of the activation resemble those found for enhancers of eukaryotic transcription. However, the nature of the enhancer of T4 late transcription is novel in that it is a structure--a break in the nontranscribed DNA stand--to which the three replication proteins bind, rather than a sequence. Since the three DNA polymerase accessory proteins are carried on the moving replication fork as part of the replisome, we postulate that viral DNA replication forks act, in vivo, as the mobile enhancers of T4 late gene transcription. Whereas Escherichia coli RNA polymerase bearing the T4 gene 55 protein can selectively recognize T4 late promoters, it is only capable of responding to the transcription-enhancing activity of the three replication proteins on acquiring an additional T4-specific modification.

DNA Replication↗
PubMed1989

Paradoxical elevation of threshold to angina pectoris by cold pressor test in men with significant coronary artery disease.

Patients with coronary artery disease (CAD) have angina pectoris at varying levels of myocardial oxygen demand. Fluctuations in coronary blood supply due to dynamic changes in coronary vasomotor tone are believed to be responsible for this variation in angina threshold. Cutaneous cold application produces an inappropriate increase in coronary vascular resistance in patients with CAD. To assess the effect of a coronary vasoconstrictor stimulus during exercise (when there are competitive stimuli for coronary dilatation), 16 men with documented CAD and angina underwent 2 exercise tolerance tests, 1 performed for control purposes and the other during cold application (hand and forearm immersed in ice). The cold pressor test elicited an increase in systolic blood pressure at rest (134 vs 159 mm Hg, p less than 0.02) at the end of stage I (145 vs 165 mm Hg, p less than 0.02) and at peak exercise (154 vs 166 mm Hg, p less than 0.05). The diastolic pressure was similarly increased during cold pressor exercise test, but the heart rate showed little or no change. Most patients (11 of 16) tolerated equal or greater double products (heart rate X systolic pressure X 10(-3) at angina (17 vs 20, p less than 0.02), 1-mm ST-segment depression (16 vs 18, p less than 0.05) and peak exercise (18 vs 20, p less than 0.08) during cold pressor exercise test as compared with the baseline exercise test, without a reduction in exercise capacity.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Effects of dosing intervals on the development of tolerance to high dose transdermal nitroglycerin.

To investigate the antiischemic efficacy and development of tolerance to transdermal nitroglycerin, 14 patients with chronic, stable angina pectoris were studied using continuous ambulatory electrocardiographic monitoring. Patients demonstrated initial hemodynamic responsiveness to sublingual nitroglycerin and were titrated to a maximally tolerated dose of 30 to 60 mg/24 hours (52 +/- 5 mg). Two crossover phases were use in a randomized, double-blind, placebo-controlled manner: continuous nitroglycerin therapy (patches containing active drug worn for 24 hours) and intermittent nitroglycerin therapy (12-hour active drug followed by a 12-hour nitrate-free period). There were no differences in frequency or duration of ischemic episodes between the placebo days of each phase. A significant effect in frequency of episodes was observed between placebo and treatment days of continuous therapy (p less than 0.05). Nonsignificant reductions in frequency and duration of ischemic episodes also occurred during intermittent therapy. The major antiischemic effect of transdermal nitroglycerin therapy occurred during the first day of treatment but was lost by 48 hours. Reductions in frequency and duration of ischemic episodes (p less than 0.05) were present on day 1 of continuous therapy but ischemic episodes returned to placebo levels by day 2, suggesting the development of tolerance. Intermittent therapy did not prevent the development of tolerance on day 2 of treatment. The results demonstrate that the use of high doses of transdermal nitroglycerin in patients with chronic, stable coronary artery disease produced a beneficial reduction in the frequency and duration of ischemia. However, the antiischemic benefit was lost between 24 nd 48 hours after the onset of continuous and intermittent therapy, presumably due to tolerance.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Cutaneous↗