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Biomedical subjects

K S Channer

Publications and source records attributed to K S Channer.

At least 55 records · Page 3Linked to original sources
PubMed2000

A comparison of a low-dose warfarin induction regimen with the modified Fennerty regimen in elderly inpatients.

OBJECTIVES: To compare a new low-dose warfarin induction regimen with the Fennerty regimen in elderly inpatients. DESIGN: Age-stratified, randomized prospective study. SUBJECTS: 120 age-stratified elderly inpatients. INTERVENTIONS: Each patient was randomized to either the new induction regimen or to a modified Fennerty regimen. MAIN OUTCOMES MEASURES: Days to therapeutic International Normalized Ratio (INR >2); days in the therapeutic range (INR 2-3) during induction; number of patients with INR >4.5; ability of day 4 INR to predict day 8 warfarin dose. RESULTS: The mean time to therapeutic INR was longer for the new induction regimen than modified Fennerty regimen in patients aged 65-75 years [4.6 (mean) +/- 1.6 (SD) days vs 3.8 +/- 0.8 days; P = 0.03] and in patients aged >75 years (4.5 +/- 1.4 days vs 3.5 +/- 0.7 days; P = 0.003). Patients spent more time in the therapeutic INR range with the new induction regimen [3.0 +/- 1.3 days vs 2.7 +/- 1.3 days (P = 0.03) for those aged 65-75 years and 2.9 +/- 1.1 days vs 2.4 +/- 1.3 days (P = 0.04 for those aged >75 years]. Fewer patients using the new regimen had INRs >4.5 in the first 8 days [1 (3%) vs 6 (20%) for 65-75 years (P < 0.05) and 1 (3%) vs 11 (37%) for >75 years (P < 0.01)]. The ability to predict the maintenance dose to within 1 mg was 55% for both regimens. CONCLUSION: The low-dose regimen has important clinical advantages over the Fennerty regimen for anticoagulating elderly inpatients.

Aged↗
PubMed2000

Aging reduces the responsiveness of coronary arteries from male Wistar rats to the vasodilatory action of testosterone.

This study was performed to examine whether aging affects the vasodilatory effects of testosterone in the coronary arteries of male rats. Isolated coronary arteries from young mature (3-4 months) and elderly (22-26 months) male Wistar rats were studied in a wire myograph. Contractile function and endothelial function were assessed by measuring vasomotor responses to 10-100 mmol/l KCl, 0.1 mmol/l prostaglandin F(2alpha) (PGF(2alpha)) and 10 micromol/l acetylcholine. Sensitivity to the vasodilatory effects of testosterone was assessed by constructing dose-response curves to concentrations between 1 micromol/l and 1 mmol/l testosterone dissolved in water in vessels maximally preconstricted with PGF(2alpha). The compliance characteristics of each vessel and serum testosterone levels from each animal were measured. Histological sections of myocardium were examined for differences in coronary artery morphology. Vessels from elderly animals were significantly more resistant to the vasodilatory effects of testosterone than vessels from young animals (P=0.001 by analysis of covariance). Vessels from elderly animals were also significantly less compliant (7.32+/-0.43 microm/mN, compared with 10.99+/-1.52 microm/mN in young animals; P=0.011), and the levels of circulating testosterone in elderly animals were lower, but not significantly so (2.04+/-0.63 nmol/l compared with 3.88+/-1.7 nmol/l; P=0.32). Vessels from elderly animals were less contractile in response to KCl than those from young animals (P=0.004 by analysis of covariance). There were no significant differences between the two groups in their responses to PGF(2alpha) or acetylcholine. Thus it is concluded that coronary arteries from elderly rats are significantly less sensitive to the vasodilatory effects of testosterone than those from young animals.

Acetylcholine↗
PubMed2000

Recombinant VIIa concentrate in the management of bleeding following prothrombin complex concentrate-related myocardial infarction in patients with haemophilia and inhibitors.

Prothrombin complex concentrates (PCCs) and, more recently, activated prothrombin complex concentrates (APCCs), are widely used for the treatment of active bleeding in haemophiliacs with inhibitors. Myocardial infarction (MI), associated with the use of these concentrates, is a well-recognized, but uncommon, complication. We review the 14 previous cases published in the literature and describe two additional patients. MI related to the use of activated and non-activated PCCs predominantly affects young patients who often have no preceding history of, or risk factors for, MI and tends to be associated with large cumulative doses of concentrate. The most frequent pathological finding is myocardial haemorrhage, with no evidence of coronary artery atheroma or thrombosis. The management of further bleeding in these patients is difficult. We have safely used recombinant factor VIIa to treat bleeding in the immediate and long-term period following PCC-related MI.

Abdomen↗
PubMed1999

How patients with heart failure are managed in the United Kingdom.

Heart failure is a major cause of morbidity and mortality world wide. In the UK it is estimated to affect one in ten octogenarians. This obviously imposes a large burden on our health care services, and the ageing of our population will only exacerbate this. In this article we have attempted to provide a general overview of the day to day management of these patients in the United Kingdom.

Delivery of Health Care↗
PubMed1999

Monitoring patients with left ventricular failure by electrical impedance tomography.

Acute left ventricular failure (LVF) is a common medical emergency but detection and monitoring of pulmonary oedema remains problematic. Fluid is an important determinant of tissue impedance. Electrical impedance tomography (EIT) is a non-invasive technique allowing localisation of impedance changes within tissue. We have investigated the relationship between LVF and the electrical impedance of lung tissue. Twenty patients with a clinical diagnosis of acute left ventricular failure were compared with 30 normal subjects. Patients were monitored using serial chest radiographs and electrical impedance tomography measurements of lung impedance during hospital admission. Radiographs were graded according to the severity of pulmonary oedema by two independent radiologists. Lung impedance was significantly (P<0.0001) lower than normal in patients with left ventricular failure. Values returned towards the normal range as LVF resolved. There was a similar improvement in the score of the chest radiographs. The electrical impedance of the lung is low in left ventricular failure and increases following treatment.

Acute Disease↗
PubMed1999

The GPIa C807T dimorphism associated with platelet collagen receptor density is not a risk factor for myocardial infarction.

The platelet collagen receptor, GPIa/IIa, is an important mediator of platelet adhesion to fibrillar collagens at sites of vascular injury. Recently, a dimorphism at nucleotide 807 of the GPIa cDNA (TTC/TTT in codon 224) was shown to be associated with variation in GPIa/IIa receptor density on the platelet surface. We conducted a case-control study to determine if the 807T allele, linked with increased GPIa/IIa density, contributed to risk of myocardial infarction (MI). DNA from 546 acute MI cases and 507 controls, all aged <75 years, was genotyped for the C807T dimorphism using the TaqManTM system of allelic discrimination. The allelic odds ratio (OR) for MI in the complete cohort was 0.88 (95% CI 0.74-1.05, P = 0.17), indicating that the 807T allele was not associated with an increased risk of MI. There was also no increased risk of MI associated with the homozygous 807TT (P = 0.22) or heterozygous 807CT (P = 0.24) genotypes or for carriers of the 807T allele in any cohort subgroup analysed. We conclude that the GPIa 807T allele is not a risk factor for MI in our population either alone or in combination with other major cardiovascular risk factors.

Adult↗
PubMed1999

The normal range for inter-arm differences in blood pressure.

OBJECTIVE: to establish the mean and normal range for the difference in simultaneous systolic and diastolic blood pressure measurements between the right and left arm. SUBJECTS: 462 subjects, age range 20-89 years, in sinus rhythm and with no history of stroke, 98 of whom had a history of cardiovascular disease or were taking vasoactive medication. METHODS: four simultaneous recordings of blood pressure in both arms were made using two automated sphygmomanometers with the subject supine after resting for 10 min. RESULTS: inter-arm systolic and diastolic blood pressure differences show a near normal distribution of values. Some individuals had clinically important differences in systolic and diastolic blood pressure between their arms. The magnitude of these differences was not related to the mean baseline blood pressure. Linear regression analysis did not demonstrate any significant relationship between inter-arm systolic or diastolic blood pressure difference and age in patients of either sex. For systolic blood pressure the mean difference between the right and left arm was 1.1 mmHg and the normal range was -9 mmHg to 11 mmHg. For diastolic blood pressure the mean difference was 0 mmHg and the normal range -10 mmHg to 10 mmHg. CONCLUSION: the frequency of significant inter-arm systolic and diastolic blood pressure differences suggests that the blood pressure should be taken in both arms at the initial consultation. At subsequent visits, the arm in which measurements are taken should be recorded in the case notes. The higher of the two readings should be used to guide further management decisions.

Adult↗
PubMed1999

An open label, randomised, crossover study comparing sotalol and atenolol in the treatment of symptomatic paroxysmal atrial fibrillation.

OBJECTIVE: To compare sotalol and atenolol in the treatment of symptomatic paroxysmal atrial fibrillation. DESIGN: Prospective, randomised, open label, crossover study. SETTING: University hospital. PATIENTS: 47 subjects aged over 50 years were recruited from the hospital outpatient department following ECG documentation of paroxysmal atrial fibrillation that coincided with symptoms. Six patients withdrew and 41 completed the trial. INTERVENTIONS: Patients were randomised to one month's treatment with sotalol 80 mg twice daily or atenolol 50 mg once daily. Treatment arms were then crossed over. Patients underwent 72 hour Holter monitoring before randomisation and repeat studies were carried out at the end of both treatment periods. Symptom assessments were completed using linear analogue scales and the Nottingham health profile. MAIN OUTCOME MEASURE: Frequency of paroxysmal atrial fibrillation; secondary outcome measures included average and total duration of paroxysmal atrial fibrillation, total ectopic count, and symptom assessments. RESULTS: A reduction in the number and duration of episodes of paroxysmal atrial fibrillation was noted following treatment with sotalol and atenolol. There was no difference in frequency of paroxysmal atrial fibrillation during treatment with sotalol or atenolol (median difference 0; 95% confidence interval (CI) 0 to 1; p = 0.47). There was no difference in total duration of paroxysmal atrial fibrillation (median difference 0 min; 95% CI -1 to 2; p = 0. 51) or in average duration (median difference 0 min; 95% CI 0 to 1; p = 0.31). No difference was found in total ectopic count between sotalol and atenolol (median difference -123; 95% CI -362 to 135; p = 0.14). Treatments were equally tolerated with no difference in linear analogue scores for symptoms of paroxysmal atrial fibrillation (median difference -5; 95% CI -20 to 5; p = 0.26) or in all categories of the Nottingham health profile. CONCLUSIONS: No difference was found in terms of ECG or symptomatic control of paroxysmal atrial fibrillation between prescribing sotalol 80 mg twice daily and atenolol 50 mg once daily. There was an improvement in paroxysmal atrial fibrillation from baseline following treatment with either sotalol or atenolol.

Adrenergic beta-Antagonists↗
PubMed1999

Spontaneous subcapsular renal haemorrhage presenting with pleuritic chest pain.

We present an unusual case of spontaneous renal subcapsular haematoma in a normal kidney presenting with pleuritic chest pain and mimicking pulmonary embolism. The literature suggests that the majority of these cases occur in association with renal tumours and that the diagnosis can best be made by computed tomographic scanning. Treatment is expectant but because of the high incidence of tumours, nephrectomy is usually necessary.

Aged↗
PubMed1999

The prothrombin 20210A allele and its association with myocardial infarction.

The relationship between the prothrombin (PT) 20210A allele and arterial disease is controversial. We conducted a case-control study to assess its contribution to risk of myocardial infarction (MI). Five hundred and thirty-nine acute MI patients and 498 control subjects aged <75 years were studied. Two percent of cases carried the PT20210A allele compared to 2.8% of controls. The odds ratio for MI was 0.72 (95% CI 0.32-1.60) indicating that the PT20210A allele confers no increased risk for MI. Subgroup analysis showed no association between the PT20210A allele and either premature MI or MI in females. We conclude the PT20210A allele is not a risk factor for MI and suggest that discrepancies in studies relating the PT20210A allele to MI may be due to difficulties in estimating its low allelic frequency in the general population and thus random differences in the observed frequencies in the control populations studied.

Aged↗
PubMed1998

A new regimen for starting warfarin therapy in out-patients.

AIMS: Oral anticoagulation is increasingly used in elderly patients with atrial fibrillation to prevent embolic phenomena. The use of anticoagulants in this population is prophylactic rather than therapeutic and so there is no urgency to establish anticoagulation within the desired therapeutic range. The aim of the study was to develop an out-patient regimen for initiation of oral anticoagulation with warfarin which requires only weekly monitoring of the International Normalized Ratio (INR). METHODS: The study was undertaken in two phases. In the first phase, factors which predict the final maintenance dosage of warfarin were defined and used to build a decision tree and dosage algorithm. In the second study the algorithm was tested. Patients were given 2 mg warfarin daily for 2 weeks and the INR at this time was used to predict the maintenance dose. Patients then attended for weekly measurements of the INR until steady state had been reached. Dosage adjustments were not made unless the INR was >4.0 or <1.5 for 2 consecutive weeks. The accuracy of the prediction was measured by calculating the mean INR of weeks 6-8 and the number of patients in the target range 2.0-3.0 was determined. RESULTS: One hundred and seven consecutive out-patients (mean age 70 years range 64-86) completed the first study. The age, sex, height, weight, alcohol intake, number of cigarettes smoked, concomitant medication, clinical evidence of right heart failure, liver failure, abnormalities in liver enzyme estimations, baseline INR and INR after 2 weeks of 2 mg warfarin daily were used in a polytomous logistic regression analysis with stepwise inclusion of factors to determine which factors influenced the eventual maintenance dosage of warfarin. The INR after 2 weeks of 2 mg warfarin therapy predicted 70% of the variability of the maintenance dose. Of other factors only the sex of the patient had a large enough effect to be included in the prediction algorithm. One hundred and six patients (mean age 71 years range 50-85 years) completed the second study. Only one patient needed a dose adjustment in the first 2 weeks of warfarin 2 mg daily (INR 4.4). Overall, 60% patients were in the narrow target range (INR 2.0-3.0) at steady state. In five patients the INR was >4.0 at any visit after the second week and needed dosage adjustment. In four patients the INR was <1.5 at steady state. CONCLUSIONS: We have developed a method of predicting the maintenance dose of warfarin in an elderly population based on the INR after 2 weeks of warfarin 2 mg daily, and the sex of the patient. This is a safe and convenient way of initiating warfarin therapy as an out-patient which requires only weekly INR checks.

Aged↗