PubMed Health⌕ Search

Biomedical subjects

P W Macfarlane

Publications and source records attributed to P W Macfarlane.

At least 19 recordsLinked to original sources
PubMed2006

Elevated troponin levels are associated with sympathoadrenal activation in acute ischaemic stroke.

BACKGROUND: It has been hypothesised that elevated serum troponin levels in acute stroke are due to myocardial damage caused by sympathoadrenal activation, which, in turn, may be due particularly to insular damage. We aimed to determine the factors associated with troponin elevation in ischaemic stroke and the prognostic value of this finding. METHODS: We studied 222 consecutive acute ischaemic stroke admissions. Serum troponin I and catecholamines were measured. Ischaemic damage on brain computed tomography (CT) scan was graded using the Alberta Stroke Program Early CT Score (ASPECTS). Electrocardiograms were classified using the Minnesota Code and the European Society of Cardiology/American College of Cardiology criteria for acute myocardial infarction. The Rankin scale was recorded at 30 days. RESULTS: Forty-five patients (20%) had troponin I >0.2 microg/l. These troponin-positive patients had higher epinephrine levels (median 0.27 vs. 0.17 nmol/l; p = 0.0002) and were more likely to have electrocardiograms coded as definite or possible acute myocardial infarction (odds ratio 3.35; 95% CI 1.26-8.93), compared with those with troponin < or = 0.2 microg/l, in univariate analysis. There were no significant associations between troponin I score and ASPECTS or insular damage on brain CT. In logistic regression analyses, elevated troponin was significantly associated with age, elevated serum creatinine and epinephrine; however, increased troponin was not an independent predictor of death or dependency (Rankin >2) at 30 days. CONCLUSIONS: Raised troponin I is associated with elevation of circulating epinephrine in acute ischaemic stroke. Activation of the sympathoadrenal system may be an important contributor to myocardial damage in these patients. Increased troponin is not associated with insular damage and does not independently predict poor outcome.

Acute Disease↗
PubMed2006

The value of the electrocardiogram in risk assessment in primary prevention: experience from the West of Scotland Coronary Prevention Study.

Electrocardiograms (ECGs) were recorded at baseline, annually thereafter, and at run-out in the West of Scotland Coronary Prevention Study to which 6595 men aged from 45 to 65 years on entry were recruited. The baseline ECGs were analyzed with respect to (a) the primary end point of the study, namely, fatal or nonfatal myocardial infarction (MI) and (b) all-cause mortality. In addition, incident MIs were reviewed to determine those detected by ECG only. Heart rate, indexed left ventricular mass, frontal T axis, and T amplitude in lead I were all significantly predictive with respect to the primary end point in a multivariate analysis. With respect to all-cause mortality, minor ST-T changes, 10-second heart rate variability, and frontal T axis were similarly predictive. Of 355 incident MIs, 47.3% were silent or unrecognized and detected by ECG only. A simple ECG-based risk prediction equation for fatal and nonfatal MI is introduced.

Aged↗
PubMed2005

Inter- and intraobserver variability in LVH and RVH reporting in pediatric ECGs.

BACKGROUND: Physicians' diagnoses are often used as the gold standard for evaluating computer electrocardiogram (ECG) interpretation programs. As part of a larger study to evaluate the Glasgow pediatric ECG analysis program, inter- and intraobserver variability in the ECG reporting of two pediatric cardiologists was examined. METHODS: The ECGs of 984 children were sent for reporting independently by two cardiologists with all identifying information except age and sex removed. Three hundred twenty ECGs had no clinical indication available, and they were thus reported "blind." For 664 ECGs, the clinical indication was known and included with the ECG trace. All ECGs reported as right ventricular hypertrophy (RVH) or left ventricular hypertrophy (LVH) were returned to the cardiologists without their knowledge for reporting a second time "blind" as to the clinical indication. RESULTS: When the cardiologists' reports were compared with each other, the provision of clinical information led to greater agreement between them for the diagnosis of LVH (kappa increased from 0.44 to 0.52) but did not substantially affect their agreement in diagnosing RVH (kappa fell from 0.66 to 0.63). Intraindividual comparisons in 166 ECGs revealed that one cardiologist was more consistent in diagnosing RVH and the other more consistent in diagnosing LVH. CONCLUSIONS: This study has demonstrated the difficulties in using cardiologists' diagnoses as the gold standard with which to evaluate pediatric ECGs.

Adolescent↗
PubMed2003

Interaction of atherosclerosis and inflammation in elderly subjects with poor cognitive function.

OBJECTIVE: To test the hypothesis that a pro-inflammatory response is associated with cognitive impairment among individuals with cardiovascular disease. METHOD: All 85-year-old inhabitants of Leiden (n = 599) were visited at their place of residence. A history of cardiovascular disease and an EKG were used as indicators of atherosclerosis. Production of the pro-inflammatory cytokine tumor necrosis factor-alpha and the anti-inflammatory cytokine interleukin-10 was assessed in a whole-blood assay using lipopolysaccharide as a stimulus. Global cognitive functioning was determined with the Mini-Mental State Examination (MMSE); attention, cognitive speed, and memory were determined with four neuropsychological tests; and a history of dementia was obtained. RESULTS: In subjects with cardiovascular disease, median MMSE scores were lower in those with a pro-inflammatory response when compared with those with an anti-inflammatory response (p = 0.02). Similar associations were found for the Stroop Test, measuring attention (p < 0.01), the Coding Test measuring cognitive speed (p = 0.02), the Word Learning Test measuring memory (p < 0.01), and the presence of dementia (p = 0.04). The associations remained unaltered after adjustments for possible confounders such as gender, level of education, use of nonsteroidal anti-inflammatory drugs, use of cardiovascular drugs, and cardiovascular risk factors. In contrast, outcomes of the cognitive tests and presence of dementia were not dependent on the inflammatory response when cardiovascular disease was absent. CONCLUSION: The combination of cardiovascular disease and a pro-inflammatory cytokine response may be associated with cognitive impairment and dementia.

Aged↗
PubMed2003

Myocardial viability as a determinant of the ejection fraction response to carvedilol in patients with heart failure (CHRISTMAS trial): randomised controlled trial.

BACKGROUND: The improvement in left-ventricular ejection fraction (LVEF) in response to beta blockers is heterogeneous in patients with heart failure due to ischaemic heart disease, possibly indicating variations in the myocardial substrate underlying left-ventricular dysfunction. We investigated whether improvement in LVEF was associated with the volume of hibernating myocardium (viable myocardium with contractile failure). METHODS: We did a double-blind, randomised trial to compare placebo and carvedilol for 6 months in individuals with stable, chronic heart failure due to ischaemic left-ventricular systolic dysfunction. We enrolled 489 patients, of whom 387 were randomised. Patients were designated hibernators or non-hibernators according to the volume of hibernating myocardium. The primary endpoint was change in LVEF, measured by radionuclide ventriculography, in hibernators versus non-hibernators, on carvedilol compared with placebo. Analysis was by intention to treat. RESULTS: 82 patients dropped out of the study because of adverse events, withdrawal of consent, or failure to complete the investigation. Thus, 305 (79%) were analysed. LVEF was unchanged with placebo (mean change -0.4 [SE 0.9] and -0.4 [0.8] for non-hibernators and hibernators, respectively) but increased with carvedilol (2.5 [0.9] and 3.2 [0.8], respectively; p<0.0001 compared with baseline). Mean placebo-subtracted change in LVEF was 3.2% (95% CI 1.8-4.7; p=0.0001) overall, and 2.9% (0.7-5.1; p=0.011) and 3.6% (1.7-5.4; p=0.0002) in non-hibernators and hibernators, respectively. Effect of hibernator status on response of LVEF to carvedilol was not significant (0.7 [-2.2 to 3.5]; p=0.644). However, patients with more myocardium affected by hibernation or by hibernation and ischaemia had a greater increase in LVEF on carvedilol (p=0.0002 and p=0.009, respectively). INTERPRETATION: Some of the effect of carvedilol on LVEF might be mediated by improved function of hibernating or ischaemic myocardium, or both. Medical treatment might be an important adjunct or alternative to revascularisation for patients with hibernating myocardium.

Adrenergic beta-Antagonists↗
PubMed2003

Gender differences in stability of the instantaneous patterns of body surface potentials during ventricular repolarisation.

Women have a higher risk of developing torsade de pointes under OT-prolonging conditions. The electrophysiological differences between the sexes that could account for this are largely unknown. The objective of the work was to evaluate gender differences in repolarisation potentials using a method that is independent of the specific electrical properties of the thorax. 1410 normal recordings from the Glasgow 12-lead ECG database and 52 normal ECG maps obtained separately in Milan were analysed. The average difference between 1 and the correlation coefficient of the instantaneous pattern at the peak of T with that at every other instant is called the early repolarisation deviation index (ERDI) for J-T peak and the late repolarisation deviation index (LRDI) for T peak-T end. In standard ECG recordings, the ERDI was 0.42 +/- 0.22 in females compared with 0.19 +/- 0.16 in males (p < 10(-6)). The LRDI was higher in males under the age of 50. In body surface maps, the ERDI was 0.32 +/- 0.21 in females against 0.16 +/- 0.17 in males (p < 0.01), and the LRDI was non-significantly higher in males. The pattern of instantaneous body surface potentials showed gender differences during repolarisation with a method that is independent of the electrical properties of the thorax.

Adolescent↗
PubMed2002

Atherosclerosis and cognitive impairment are linked in the elderly. The Leiden 85-plus Study.

Post-mortem analyses suggest that atherosclerosis more often contributes to late-onset dementia than hitherto expected. We set out to further unravel the relation between atherosclerosis and cognitive impairment. We therefore tested the hypothesis that the number of cardiovascular pathologies is positively associated with cognitive impairment in elderly subjects, and that the smaller number of cardiovascular pathologies in women explains the better cognitive function of elderly women. Within the Leiden 85-plus Study, we assessed the atherosclerotic burden by counting the number of cardiovascular pathologies in the medical histories of a population-based sample of 599 subjects aged 85 years (response 87%). Significantly more men than women had a history of cardiovascular pathologies (67% compared to 59%, P<0.001). In addition, cognitive function was assessed. All subjects completed the Mini-Mental State Examination (MMSE). Cognitive speed and memory were determined with specific neuro-psychological tests in those with a MMSE-score above 18 points. There was a highly significant dose-response relationship between the number of cardiovascular pathologies and cognitive impairment for both men and women. The median MMSE-score was 26 points in subjects without cardiovascular disease and decreased to 25 points for subjects who had two or more cardiovascular pathologies (P for trend =0.003). Similar associations were found for cognitive speed but not for memory. Our data confirm that in old age atherosclerosis significantly contributes to cognitive impairment. Since treatments for atherosclerosis appear to be particularly effective in elderly people, we consider our finding of utmost clinical importance in possibly preventing cognitive impairment and late-onset dementia.

Aged↗
PubMed2001

Clinical significance of abnormal T waves in patients with non-ST-segment elevation acute coronary syndromes.

T-wave abnormalities are common electrocardiographic occurrences in patients with non-ST-segment elevation acute coronary syndromes. Although these abnormalities are considered relatively benign, physicians use them to guide therapies. The study objective was to examine the prognostic predictive information of T-wave abnormalities in the setting of unstable coronary artery disease. The T-wave abnormality criterion was based on a new set of normal T-wave amplitude limits differentiated by gender, age, electrocardiographic lead, and QRS axis. Four hundred sixty-eight patients suspected of an acute ischemic incident and considered ineligible for reperfusion therapy were included. Thirteen categories of T-wave abnormalities were tested prospectively. The primary 30-day end point was the combination of refractory angina, myocardial infarction, or death. Quantitative T-wave analysis in an electrocardiographic core laboratory revealed 6 of 13 prespecified categories of T-wave abnormalities that were significantly associated with an adverse outcome. T-wave abnormalities had no prognostic value when ST-segment depression was also present, but this occurred in only 7.9% of patients. T-wave abnormalities as the sole manifestation of ischemia were common (74.4%). Patients with abnormal T waves in > or =1 of 6 selected abnormality categories (70.3%) had a significantly higher risk of death, acute myocardial infarction, and refractory angina (11% vs 3%; p = 0.018). Thus, T-wave abnormalities in patients presenting with non-ST-segment elevation acute coronary syndromes are common and should not automatically be regarded as benign phenomena. Quantitative T- wave analysis provides optimal risk stratification.

Aged↗
PubMed2001

Pravastatin and the development of diabetes mellitus: evidence for a protective treatment effect in the West of Scotland Coronary Prevention Study.

BACKGROUND: We examined the development of new diabetes mellitus in men aged 45 to 64 years during the West of Scotland Coronary Prevention Study. METHODS AND RESULTS: Our definition of diabetes mellitus was based on the American Diabetic Association threshold of a blood glucose level of >/=7.0 mmol/L. Subjects who self-reported diabetes at baseline or had a baseline glucose level of >/=7.0 mmol/L were excluded from the analyses. A total of 5974 of the 6595 randomized subjects were included in the analysis, and 139 subjects became diabetic during the study. The baseline predictors of the transition from normal glucose control to diabetes were studied. In the univariate model, body mass index, log triglyceride, log white blood cell count, systolic blood pressure, total and HDL cholesterol, glucose, and randomized treatment assignment to pravastatin were significant predictors. In a multivariate model, body mass index, log triglyceride, glucose, and pravastatin therapy were retained as predictors of diabetes in this cohort. CONCLUSIONS: We concluded that the assignment to pravastatin therapy resulted in a 30% reduction (P:=0.042) in the hazard of becoming diabetic. By lowering plasma triglyceride levels, pravastatin therapy may favorably influence the development of diabetes, but other explanations, such as the anti-inflammatory properties of this drug in combination with its endothelial effects, cannot be excluded with these analyses.

Anticholesteremic Agents↗
PubMed2001

The role of myocardial perfusion scanning, heart rate variability and D-dimers in predicting the risk of perioperative cardiac complications after peripheral vascular surgery.

OBJECTIVES: To study the value of a number of proposed prognostic factors in prediction of the risk of perioperative cardiac events after vascular surgery. DESIGN AND METHODS: Two hundred and ninety-seven patients undergoing peripheral vascular surgery were prospectively studied. Patients underwent preoperative 24 h ambulatory electrocardiography, measurement of haemostatic variables, myocardial assessment of perfusion by dipyridamole-thallium scintigraphy and radionuclide ventriculography. The primary endpoint was cardiac death or nonfatal myocardial infarction within 30 days of surgery. A combined endpoint included the primary endpoint plus occurrence of cardiac failure, unstable angina or serious arrhythmias. RESULTS: The primary endpoint occurred in 21 (7%), and the combined endpoint in 41 (14%) of patients. On multivariate analysis, increased age, previous myocardial infarction, aortic surgery, impaired heart rate variability and a positive thallium scan were independent predictors of primary end-points. Preoperative atrial fibrillation and increased fibrin D-dimer were additional predictors of the combined endpoint. Construction of receiver-operator characteristic curves to examine the incremental value of predictive models showed that sensitivity and specificity of clinical data alone for primary endpoints was 71% and 72% respectively, while for the full model (incorporating heart rate variability and thallium data) this rose to 84% and 80% (p=0.0001). CONCLUSIONS: Preliminary screening using clinical data has limited value in risk assessment prior to vascular surgery but preoperative heart rate variability, D-dimers and thallium scanning provide modest incremental predictive value.

Aged↗
PubMed2001

Age, sex, and the ST amplitude in health and disease.

Electrocardiograms (ECGs) from 1,338 apparently healthy adults were analyzed to calculate limits of normality of a variety of ECG measurements. A second set of ECGs from 503 healthy Chinese individuals was also available for comparison of selected normal ranges. It was found that the normal limits of the ST amplitude in healthy individuals decrease with increasing age and, in general terms, are lower in women than in men, particularly in the precordial leads. For example, the upper limit of normal ST amplitude in V3 in a 25-year-old man is 0.31mV but is only 0.11 mV in a woman of the same age. On the other hand, the age-dependent contribution to variation in the upper limit of normal of ST amplitude is effectively confined to men. The one exception to this appears to be the mean ST slope in V2, which decreases with increasing age in both men and women and is higher in the former compared to the latter. Recommended ECG related criteria, particularly in V1, for administration of thrombolytic therapy appear to be neither age nor sex dependent, which is a significant shortcoming given the foregoing information.

Adult↗
PubMed2001

Reproducibility of a non-invasive real-time measure of cardiac parasympathetic activity.

The NeuroScope is a new device which produces a continuous real-time index of cardiac parasympathetic activity (the CIPA) and accurately measures RR intervals. The reproducibility of the CIPA has not yet been assessed. This study was designed to assess the reproducibility of a 5 minute recording of the CIPA using the NeuroScope and compare it with that of conventional heart rate variability (HRV) measures. 50 subjects (31 male, 19 female) aged 21-77 years were recruited. 11 of these were apparently healthy and 39 were patients with a variety of cardiological problems. Two 5 minute recordings of CIPA and RR intervals for each subject were made with a 2-3 minute break between recordings. The limits of agreement for the CIPA were such that the second estimate was between 72 and 140% of the first estimate, 95% of the time. The limits of agreement for other indices of HRV, namely SDNN, rMSSD, In low-frequency HRV and In high-frequency HRV, were 61-157%, 68-153%, 77-131% and 76-133%. The short-term reproducibility of a 5 minute recording of CIPA is moderate and better than simple time-domain but not frequency-domain measures of HRV.

Aged↗
PubMed2000

CPR '98: a practical multimedia computer-based guide to cardiopulmonary resuscitation for medical students.

This paper describes an initiative to build a multimedia computer-based teaching package for cardiopulmonary resuscitation. The project resulted from a perceived gap in the undergraduate medical curriculum allied to concern from medical students. The software application was designed to be networked and used as an adjunct to taught life support courses for undergraduate medical students. The package comprises tutorials and test questions in basic and advanced life support. It incorporates sound, video, graphics and animation to illustrate the techniques involved and is distributed on CD ROM for the PC. The content is based on the 'Advanced Life Support Manual', produced by the Resuscitation Council (UK) and incorporates all changes to the guidelines made during 1997 and 1998. The basic life support section has been networked locally, and has been tested on more than 60 third year medical students attending a local basic life support course. It was found that students who used the package performed significantly better in theoretical assessments than those who did not.

Cardiopulmonary Resuscitation↗
PubMed1999

The design of a prospective study of Pravastatin in the Elderly at Risk (PROSPER). PROSPER Study Group. PROspective Study of Pravastatin in the Elderly at Risk.

The PROspective Study of Pravastatin in the Elderly at Risk (PROSPER) is a randomized, double-blind, placebo-controlled trial designed to test the hypothesis that treatment with pravastatin will diminish risk of subsequent major vascular events in a cohort of men and women (70 to 82 years old) with preexisting vascular disease or significant risk of developing this condition. Five thousand eight hundred four men and women in addition to receiving advice on diet and smoking, have been randomized equally to treatment with 40 mg pravastatin/day or matching placebo in 3 centers (Cork, Ireland, Glasgow, Scotland, and Leiden, The Netherlands). Following an average 3.5-year intervention period, a primary assessment will be made of the influence of this therapy on major vascular events (a combination of coronary heart disease, death, nonfatal myocardial infarction, and fatal and nonfatal stroke). A number of additional analyses will also be conducted on the individual components of the primary end point, on men, on women, and on subjects with and without previous evidence of vascular disease. Finally, an assessment will be made of the effects of treatment on cognitive function, disability, hospitalization or institutionalization, vascular mortality, and all-cause mortality.

Aged↗
PubMed1999

Can single-lead computerized electrocardiography predict myocardial infarction in young and middle-aged men? The Tromsø study.

BACKGROUND: In epidemiological studies, the electrocardiogram has often been interpreted by means of a categorical classification. Computerized recording offers the possibility of analysing electrocardiographic measurements as continuous variables. OBJECTIVE: To test the hypothesis that duration of QRS complex and T-wave inversion would be independent predictors of myocardial infarction. METHODS: In a population-based study, we prospectively investigated the risk of developing myocardial infarction according to duration of ORS complex and peak-to-peak T-wave amplitude measured from lead I of the 12-lead electrocardiogram by computerized electrocardiography. In total 6628 men aged 25-61 years who had not previously suffered a myocardial infarction were followed up for 3.9 years. RESULTS: Eighty-two first myocardial infarctions (55 non-fatal and 24 fatal myocardial infarctions and three sudden deaths) were identified. The risk of myocardial infarction increased with duration of ORS complex and with decreasing T-wave amplitude. A proportional hazards model with adjustment for possible confounders yielded a relative risk of myocardial infarction of 3.74 (P for linear trend 0.015) for duration of QRS complex > or = 120 ms compared with duration of QRS complex <80 ms. The multivariate relative risk for T-wave amplitude > or = 0.35 mV compared with T-wave amplitude < 0.20 mV was 0.55 (P for linear trend 0.036). When both duration of ORS complex and T-wave amplitude were included in the multivariate model, T-wave amplitude retained its predictive power, whereas duration of ORS complex became marginally no longer significant (P=0.067). CONCLUSIONS: Peak-to-peak T-wave amplitude from lead I is an independent predictor of myocardial infarction in men who have not previously suffered a myocardial infarction. Greater duration of ORS complex clearly indicates a higher risk of myocardial infarction. However, when T-wave amplitude is included as a covariate, the predictive power of duration of QRS complex does not remain significant. Single-lead electrocardiography is a feasible method for improving the assessment of the relative risk of myocardial infarction.

Adult↗