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N P Campbell

Publications and source records attributed to N P Campbell.

At least 19 recordsLinked to original sources
PubMed2001

5-fluorouracil-induced cardiotoxicity mimicking myocardial infarction: a case report.

BACKGROUND: Severe cardiotoxicity is a documented, but very unusual side-effect of intravenous 5-fluorouracil therapy. The mechanism producing cardiotoxicity is poorly understood. CASE PRESENTATION: A case of 5-fluorouracil-induced cardiotoxicity, possibly due to coronary artery spasm, and mimicking acute anterolateral myocardial infarction is presented and discussed. Electrocardiographs highlighting the severity of the presentation are included in the report along with coronary angiograms demonstrating the absence of significant coronary atherosclerosis. CONCLUSION: Severe 5-fluorouracil-induced cardiotoxicity is rare, but can be severe and may mimic acute myocardial infarction, leading to diagnostic and therapeutic dilemmas. Readministration of 5-fluorouracil is not advised following an episode of cardiotoxicity.

Aged↗
PubMed2000

Neuropeptide variability in man.

BACKGROUND: Previous studies have established short-term variability in the circulating plasma levels of cardiac peptides such as atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP). Our aim was to investigate whether such variable patterns could be observed in other vasoactive peptides. METHODS: We measured the immunoreactivity of vasoactive intestinal polypeptide (VIP), neuropeptide Y (NPY), endothelin-1 (ET-1) and calcitonin gene-related peptide (CGRP) in peripheral venous plasma collected at 2-min intervals over a 20-min period from patients with chronic cardiac failure (CCF) and from control subjects. In a second study, blood samples were obtained at 2-min intervals from the pulmonary artery, femoral artery and antecubital vein from patients with normal cardiac function while right atrial pressure and heart rate were constant. RESULTS: Peripheral blood VIP, NPY and ET-1 had peaks and troughs (levels > 2SD from the mean) in both patients and controls, with approximate intervals of 10 min. Levels of CGRP showed little variation. The overall levels [median (range); pmol L-1] of VIP [patients 27 (2.1-85.5); controls 9.8 (0-34)] and NPY [patients 20 (0-110); controls 12 (5-19)] were higher in patients (P < 0.05). Circulating plasma levels of ET-1 and CGRP were about the same in both groups [ET-1: patients 18 (2-84); controls 18 (0-48); CGRP: patients 4 (1-18.5), controls 5.5 (1-15); P = NS]. Levels of CGRP, VIP and ET-1 were similar in the pulmonary and femoral arteries, whereas systemic arterial levels of NPY were higher than in the pulmonary artery. CONCLUSIONS: The data demonstrate marked variability in circulating levels of the neuropeptides studied. In addition, peaks and troughs were observed every 10-15 min from all three vascular beds. If these peptides are secreted in a pulsatile pattern, then interpretations of single measurements should be guarded. Furthermore, this study raises interesting questions about the physiology of hormone secretion in man.

Aged↗
PubMed2000

Comparative physiological study of arbutamine with exercise in humans.

Pharmacological stress testing may be used in the diagnosis of coronary artery disease when there are contra-indications to the use of conventional exercise protocols. The responses to such testing using arbutamine and to conventional treadmill exercise were compared in eight patients. Respiratory gas analysis and cardiovascular observations were performed during both tests. For an equivalent increment in heart rate, both protocols increased systolic blood pressure and serum lactate. Minute ventilation and oxygen consumption also rose during both protocols, but much more so with exercise. The end-tidal partial pressure of CO(2) [35.1 (S.D. 3. 1) to 30.8 (6.6) mmHg] and the dead space/tidal volume ratio (V(D)/V(T)) [0.37 (0.09) to 0.33 (0.08)] fell significantly during arbutamine infusion, but the respiratory exchange ratio did not change during either protocol. Oxygen pulse, a marker of stroke volume, did not change significantly after arbutamine, but rose markedly after exercise [arbutamine, 3.9 (1.1) to 3.37 (0.7) ml. min(-1).beat(-1); exercise, 4.7 (1.4) to 16.1 (4.6) ml.min(-1). beat(-1) (P<0.0001 compared with baseline); difference between peak responses: P<0.0001]. We conclude that arbutamine simulates some of the physiological responses to exercise, although a number of these responses are less marked than during conventional exercise, in particular cardiac output (oxygen pulse). An increase in ventilation is produced, possibly due to direct stimulation of arterial chemoreceptors. These data suggest that the main action of arbutamine is to increase central drive rather than to establish peripheral demand.

Adrenergic beta-Agonists↗
PubMed1999

Randomised comparison of electrode positions for cardioversion of atrial fibrillation.

OBJECTIVE: To compare the relative efficacy of anteroanterior v anteroposterior electrode pad positions for external cardioversion of atrial fibrillation. DESIGN: Prospective randomised trial. SETTING: Tertiary referral cardiology centre in the United Kingdom. PATIENTS: 90 patients undergoing elective cardioversion for atrial fibrillation. INTERVENTIONS: Cardioversion was attempted with self adhesive electrode pads with an area of 106 cm2 placed either in the anteroanterior (AA) or anteroposterior (AP) positions. Initial shock was 100 J which, if unsuccessful, was followed by 200 J, 300 J, and 360 J if required. Peak current and transthoracic impedance were measured. MAIN OUTCOME MEASURES: Cardioversion success rate and energy requirements. RESULTS: Cardioversion was successful in 81% of the patients (73/90). There was no statistically significant difference in the cardioversion success rate (AA 84%, 38/45 patients; AP 78%, 35/45 patients; p = 0.42) or mean (SD) energy requirement for all patients (AA 223 (96.1) J; AP 232 (110) J) or for patients who were successfully cardioverted (AA 197.9 (82.4) J; AP 195.4 (97.2) J; p = 0.9) between the two pad positions. The mean transthoracic impedance (TTI) for the first shock (AA 77.5 (18.4) ohms; AP 73.7 (18.7) ohms; p = 0.34) was not significantly different between the two groups. TTI correlated significantly with body mass index, percentage body fat, and chest AP diameter. There was a progressive decrease in TTI with serial shocks. While aetiology and TTI were the two independent significant predictive factors for energy requirement, duration of atrial fibrillation was the only independent predictor of cardioversion success in a multivariate analysis. CONCLUSIONS: Electrode pad position is not a determinant of cardioversion success rate or energy requirement.

Aged↗
PubMed1997

Non-invasive measurement of cardiac output and ventricular ejection fractions in chronic cardiac failure: relationship to impaired exercise tolerance.

1. The role of cardiac output limitation in the pathophysiology of exercise in patients with chronic failure remains undefined. During steady-state submaximal exercise, oxygen uptake is similar in patients and control subjects, but it is not known if cardiac output is also similar. We wished to determine if the reduced exercise tolerance of patients with chronic cardiac failure during such exercise is related to reduced cardiac output, or to peripheral factors. 2. Ten male patients with stable chronic failure and ten age-matched male normal controls were studied at rest and during exercise. Each subject performed a familiarization exercise test, a symptom-limited maximal exercise test and two submaximal exercise tests. Cardiac output was measured by a carbon dioxide rebreathing method. We also measured oxygen consumption, ventilation, Borg score of perceived exertion and venous lactate concentration, and ejection fractions. 3. As expected, patients had lower peak oxygen consumption [median (range) 1.18 (0.98-1.76) versus 1.935 (1.53-2.31) l/min; P < 0.001], lower peak venous lactate concentration but a similar overall level of perceived exertion. At the same submaximal workload, patients and control subjects had similar oxygen consumption [0.67 (0.59-0.80) versus 0.62 (0.52-0.82) l/min] and cardiac output [6.92 (5.79-9.76) versus 7.3 (5.99-10.38) l/min] but the patients had a greater perceived level of exertion [Borg score: 4 (1-6) versus 3 (1-5); P < 0.005], higher venous lactate concentration [1.6 (1-3.3) versus 1.14 (0.7-1.7) mmol/l; P < 0.05] and higher heart rate [106 (89-135) versus 87 (69-112) beats/ min; P < 0.005]. 4. During submaximal exercise at a similar absolute workload, patients with cardiac failure have a similar oxygen uptake and cardiac output but greater anaerobiosis and increased fatigue when compared with normal subjects. These findings appear to relate predominantly to changes that occur in the periphery rather than abnormalities of central cardiac function.

Adult↗
PubMed1997

Responses of atrial natriuretic peptide and brain natriuretic peptide to exercise in patients with chronic heart failure and normal control subjects.

Atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) are known to be elevated in patients with chronic heart failure at rest. While it is known that during exercise the circulating level of ANP increases in patients with heart failure, the response of BNP to exercise in these patients relative to control subjects is unclear. Ten patients with stable chronic heart failure and 10 normal control subjects performed symptom-limited exercise with respired gas analysis. All patients had depressed left ventricular ejection fractions (LVEF). Patients had lower peak oxygen consumption PVo2) than the control group [median (range) 1.18 (0.98-1.76) vs. 1.94 (1.53-2.31) L min-1; P < 0.001]. Circulating plasma levels of ANP and BNP were higher at rest in patients than in control subjects [ANP 335 (140-700) vs. 90 (25-500) pg mL-1; BNP 42 (25-50) vs. 20 (10-20) pg mL-1], and at peak exercise [ANP 400 (200-1000) vs. 130 (10-590); BNP 46 (40-51) vs. 20 (10-30)]. The rise in ANP at peak exercise was significant in patients compared with the resting level, but not in control subjects. For BNP, there was a significant rise in patients but no change in control subjects. The circulating plasma levels of both peptides showed a strong negative correlation with LVEF (ANP, P < 0.005; BNP, P < 0.0001) and, to a less extent, with RVEF. It is possible that BNP may give a better indication of cardiac function.

Adult↗
PubMed1997

Exercise responses in patients with IDDM.

OBJECTIVE: The hemodynamic, respiratory, and metabolic responses to exercise were studied in IDDM patients and control subjects to detect diabetic cardiomyopathy. RESEARCH DESIGN AND METHODS: Eight subjects aged 25-40 years with diabetes of at least 10 years' duration were compared with eight control subjects aged 21-46 years. All subjects underwent a progressive incremental bicycle exercise test with measurement of gas exchange, blood glucose, lactate, fat metabolite, and catecholamine levels and two steady-state exercise tests with measurement of cardiac output by a CO2 rebreathing method. A new first-pass radionuclide method was used to measure cardiac ejection fractions (EFs) at rest, peak exercise, and steady-state exercise. RESULTS: The peak achieved oxygen consumption was similar in the diabetic and control subjects (29.9 [25.1-34.6] and 31.4 [26.9-35.9] ml.min-1.kg-1, respectively; mean [95% CI]). There were no significant differences in heart rate, double product, ventilation, respiratory exchange ratio, or ventilatory equivalents for oxygen and CO2 during the incremental test. Glucose levels were higher in the diabetic subjects, but there were no significant differences in levels of lactate, catecholamines, free fatty acids, glycerol, or beta-hydroxybutyrate. Left ventricular EF fell from rest to peak exercise within the diabetic group (66.0% [59.6-72.4] at rest; 53.6% [45.6-61.6] at peak; P < 0.05) but this did not differ significantly from the control group (58.7% [52.3-65.1] at rest; 60.3% [48.9-71.7] at peak). Right ventricular EFs were similar in each group, and there was no reduction in peak filling rate to suggest diastolic dysfunction. The cardiac output responses to exercise were also similar in the two groups. CONCLUSIONS: There is no evidence of impairment of the exercise response in subjects with long-standing diabetes, and the apparent fall in left ventricular EF at peak exercise could be related to hemodynamic adaptation.

Adult↗
PubMed1996

Angina in McArdle's disease.

McArdle's disease (myophosphorylase deficiency) results in the inability to metabolise skeletal muscle glycogen to lactate. A patient with this condition developed angina and therefore offered a unique opportunity to explore the differential expression of the defective myophosphorylase gene in skeletal and cardiac muscle.

Aged↗
PubMed1994

Efficacy of 100 mg of double-bolus alteplase in achieving complete perfusion in the treatment of acute myocardial infarction.

OBJECTIVES: The purpose of this study was to assess the efficacy of 150 mg of aspirin plus 100 mg of alteplase, administered as two intravenous bolus injections of 50 mg each given 30 min apart, and followed by intravenous heparin, on infarct-related coronary artery patency (Thrombolysis in Myocardial Infarction [TIMI] flow grade 3). BACKGROUND: Previous workers have shown in animals that reducing the duration of an infusion of recombinant tissue-type plasminogen activator increases the initial rate of thrombolysis, resulting in high early infarct-related coronary artery patency rates. The logical progression of this idea is bolus administration. METHODS: Consecutive patients presenting up to 6 h from the onset of symptoms were recruited for the study. Angiography was performed at 60 and 90 min after the first bolus and between 19 to 48 h after study entry. Patients were followed up for 1 month. RESULTS: At 60 min, angiography revealed infarct-related coronary artery patency of TIMI flow grade 3 in 55 (86%) of 64 patients (95% confidence interval [CI] 75% to 93%) and TIMI flow grade 2 or 3 in 58 (91%) of 64 patients (95% CI 81% to 97%). At 90 min, infarct-related artery patency of TIMI flow grade 3 was achieved in 74 (88%) of 84 patients (95% CI 79% to 94%) and TIMI flow grade 2 or 3 in 78 (93%) of 84 patients (95% CI 85% to 97%). Two patients (2.4%) had early angiographic reocclusion whereas 10 (11.9%) had late reinfarction. Bleeding episodes were mostly minor, and there was no cerebrovascular bleeding. Five patients (6.0%) died within 1 month of the acute myocardial infarction. CONCLUSIONS: In 84 patients with acute myocardial infarction, administration of 100 mg of double-bolus (2 x 50 mg) alteplase, aspirin and heparin is associated with remarkably high early infarct-related coronary artery patency rates (TIMI flow grade 3) of 86% and 88%, respectively, at 60 and 90 min.

Adult↗
PubMed1994

Non-invasive measurement of cardiac output by a carbon dioxide rebreathing method at rest and during exercise.

Cardiac output was measured in 11 patients undergoing routine cardiac catheterization using a carbon dioxide rebreathing technique and compared with cardiac output measured by direct Fick and thermodilution. The carbon dioxide rebreathing technique gave consistently lower values for cardiac output than the other two methods (mean difference -0.73, 95% CI -0.95 to -0.51 l.min-1 with the direct Fick and -0.72, 95% CI -1.19 to -0.26 l.min-1 with thermodilution). The direct Fick and thermodilution methods gave similar results (mean difference -0.08, 95% CI -0.32 to 0.16 l.min-1). Cardiac output was also measured in 10 healthy subjects at rest and during two steady-state levels of exercise using the carbon dioxide rebreathing technique. Measurements were made in triplicate on 3 separate days. The technique gave reproducible results between replicates at rest (coefficient of variation 9.1%) and became more reproducible on exercise (coefficients of variation 5.6% and 5.4% respectively at each exercise level). There was a good correlation between cardiac output and oxygen consumption (r = 0.98). The carbon dioxide rebreathing technique is a feasible non-invasive way of measuring cardiac output. It tends to underestimate cardiac output at rest but is reproducible and becomes more so on exercise which is where it should be of most value.

Adult↗
PubMed1994

Variable patterns of atrial natriuretic peptide secretion in man.

Peripheral circulating levels of atrial natriuretic peptide may exhibit short-term variation compatible with a pulsatile pattern of secretion. We obtained samples every 2 min for 90 min from the antecubital vein of 16 patients with chronic cardiac failure and 13 controls. Overall levels were higher in the patients (median and quartiles 230 (125,325) vs. 26 (16,48) ng l-1; P < 0.001). In both groups there was considerable variability, with 10 (2-12) peaks, 9 (7-15) troughs (both defined as > 2 SD from the mean) and 16 (13-18) pulses (defined by computer) during the sampling period in controls, and a similar number in patients. We then carried out simultaneous sampling in the pulmonary artery, femoral artery and peripheral vein in eight subjects with normal cardiac function and six patients with impaired function due to valvular heart disease. The pattern of variability was preserved in all three sites in both groups, suggesting intermittent secretion rather than variable breakdown of the peptide in the lung. No changes in right atrial pressure or heart rate were observed to coincide with the variations, but levels of the peptide in the pulmonary artery correlated with right atrial pressure in patients (r = 0.87; P < 0.05). The mechanism of such periodicity and its pathophysiological importance remain unknown.

Adult↗
PubMed1994

Direct access exercise electrocardiography: a new service that improves the management of suspected ischaemic heart disease in the community.

OBJECTIVE: To assess the safety and value of an exercise electrocardiography service for the diagnosis of suspected ischaemic heart disease to which general practitioners have direct access. DESIGN: Direct access to a hospital exercise electrocardiography service was offered on a trial basis to 122 general practitioners in a defined urban area. Maximal exercise tests were performed according to the modified Bruce protocol and the results were dispatched promptly to the referring doctors who were responsible for the subsequent management of their patients. SETTING: All general practices in north and west Belfast (combined list size about 180,000) and the regional medical cardiology centre. PATIENTS: 212 request forms were received in a two year period and 192 eligible patients attended for exercise testing. All patients were suspected to have pain due to myocardial ischaemia, were aged < or = 65, and had no contraindications to exercise testing. MAIN OUTCOME MEASURES: Proportion of general practitioners who used the service. Proportion of exercise tests that were positive. Referring doctors' assessment of the service. RESULTS: 43% of general practitioners referred patients and 34 tests (18%) were positive. No complications occurred. The pretest likelihood of ischaemic heart disease, assessed by the referring doctor, was high in 48 (25%), moderate in 82 (43%), and low in 62 (32%). A high pretest likelihood of ischaemic heart disease predicted a positive test result with a sensitivity of 50% and specificity of 80%. General practitioners decided to refer 19 (10%) patients to a hospital cardiology department for further assessment, including 16 of the 34 who had a positive exercise test. In most cases the service was found to be helpful and 97% of patients would have been referred directly to a hospital cardiology clinic if it had not been available. CONCLUSIONS: Direct access exercise electrocardiography for patients with suspected ischaemic heart disease is safe, feasible, and helpful to general practitioners. This service seems to reduce the number of patients referred to cardiology outpatient clinics and to facilitate the management of these patients in the community.

Cardiology Service, Hospital↗
PubMed1991

Long-term function in University of Cape Town prostheses in the tricuspid position.

A 55-year-old woman undergoing triple-valve replacement was found at operation to have a well preserved and functioning University of Cape Town prosthesis that had been inserted 18 years earlier for tricuspid stenosis. Case reporting, valve reappraisal, and factual updating on another case, the world's first documented tricuspid valve replacement for Ebstein's anomaly, are presented. These two remarkable in vivo successes speak well for this historic collar stud valve.

Female↗
PubMed1991

Anistreplase in early acute myocardial infarction and the one-year follow-up.

Of consecutive patients seen with first myocardial infarction (88 of whom were treated out-of-hospital by mobile coronary care staff), 139 received 30 units of intravenous anistreplase at a mean of 101 minutes (range 35-180) from onset of symptoms. Thrombolysis in myocardial infarction patency grade 2 or 3 was found in 76/91 (83.5%) patients. At 3-4 months after hospital discharge, the mean global left ventricular ejection fraction and mean infarct-related regional third ejection fraction declined with increasing delay to anistreplase. For the first, second and third hour administrations, global ejection fraction was 54%, 50% and 45% (P = 0.002) and for regional third ejection fractions 49%, 43% and 41% (P = 0.02) respectively. Of the patients, 130 were reviewed at approximately 1 year: reinfarction had occurred in 9, 6 had undergone coronary angioplasty and 1 had coronary arterial bypass grafting performed since discharge. Mean global left ventricular ejection fraction was 52% and mean infarct-related regional third ejection fraction was 51%. Thus, intravenous anistreplase induces high rates of arterial patency. Global and regional third ejection fractions decline with increasing delay in the time of administration of anistreplase. Mortality and morbidity is low in the first year.

Adult↗