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Biomedical subjects

K S Channer

Publications and source records attributed to K S Channer.

At least 91 records · Page 5Linked to original sources
PubMed1995

Xamoterol improves the control of chronic atrial fibrillation in elderly patients.

Twenty digitalized elderly patients with chronic atrial fibrillation were randomized into a double-blind cross-over study. None was in overt heart failure and all were taking < 80 mg frusemide daily. They received xamoterol 200 mg b.d. for 2 months with their usual dose of digoxin for 1 month and placebo digoxin for the other month. Twenty-four-hour heart rate analysis was done at baseline and at the end of each treatment period. Compared with baseline digoxin, xamoterol alone significantly increased nocturnal minimum heart rate [85 +/- 17 vs. 62 +/- 9 (mean +/- SD), p < 0.0001] without affecting daytime maximum heart rate (132 +/- 18 vs. 122 +/- 20, p = NS). Compared with baseline digoxin, xamoterol plus digoxin significantly increased nocturnal minimum heart rate (68 +/- 8, p < 0.05) and reduced daytime heart rate (114 +/- 17, p < 0.05). The mean number of pauses > 1.5 s was significantly reduced by xamoterol alone. Walking distance in 6 minutes was 406.1 +/- 27.1 m (mean +/- SE) at baseline and improved significantly on both treatments (450.3 +/- 19.8 on xamoterol; p < 0.02 and 453.7 +/- 19.2 on xamoterol plus digoxin; p < 0.01). No significant change was found in subjective measurements of palpitations, breathlessness and well-being using visual analogue scales. Xamoterol combined with digoxin improves effort tolerance and heart-rate control by reducing diurnal tachycardia and nocturnal bradycardia and pauses.

Adrenergic beta-Agonists↗
PubMed1995

Effect of the calcium antagonist amlodipine on the two phases of hypoxic pulmonary vasoconstriction in rat large and small isolated pulmonary arteries.

Calcium antagonists inhibit hypoxic pulmonary vasoconstriction (HPV), which was recently shown to be biphasic in isolated vessels, but the sensitivity of the two phases to calcium antagonism is unknown. We studied HPV in rat isolated large pulmonary arteries (PA) and resistance pulmonary arteries (PRV), using a small vessel myograph. Two phases of acute hypoxic pulmonary vasoconstriction were confirmed to occur in both sizes of vessel. The first phase was short-lived and was followed by a more persistent phase of gradual onset. The magnitude of the first phase of contraction was greater than the second (p < 0.01). The first phase was reproducible, but the second was variable. Tension generated per square millimeter of vessel during both phases of hypoxic contraction was significantly greater in PRV than in PA (p < 0.05). Amlodipine caused dose-dependent inhibition of the first phase of HPV (p = 0.01), with a greater effect in PRV (p < 0.01). The second phase was not significantly inhibited. These results confirm that HPV is biphasic in isolated large and small PA, with a greater sensitivity of the first phase to calcium antagonism. Therefore, the first phase may represent HPV as observed in vivo.

Amlodipine↗
PubMed1995

Improving the interpretation of electrocardiographs in an accident and emergency department.

In this study we have examined the ability of senior house officers in the Accident and Emergency (A&E) Department to interpret electrocardiographs (ECGs) and tested the value of a single seminar and guidelines on interpretation. We prospectively audited ECG interpretation taken from notes over a two-month period and repeated this audit following a single seminar by a consultant cardiologist and after the issue of guidelines. A formal test of interpretation of a set of 20 ECGs by senior house officers in A&E was also carried out. 245 case notes were reviewed and in one third the ECG was interpreted incorrectly by senior house officers in A&E but incorrect clinical management followed in only 3.2% of cases. Following the intervention, 242 case notes were reviewed and serious misinterpretations were halved as was the number of patients mismanaged as a result (1.7%). In conclusion, formal training in ECG interpretation can reduce serious errors.

Clinical Competence↗
PubMed1994

Changes in haemodynamic variables during transurethral resection of the prostate: comparison of general and spinal anaesthesia.

We have compared changes in haemodynamic variables before and during transurethral resection of the prostate in 22 patients under general or spinal anaesthesia. In the general anaesthetic group there was a significant decrease in cardiac output (mean 32% (SEM 5%)) and mean arterial pressure (14% (3%)) after induction of anaesthesia and a significant decrease (27% (3%)) in heart rate before the start of resection. Otherwise, variables remained close to baseline values. In the subarachnoid block group, mean arterial pressure decreased after induction (16% (2%)), but overall variables remained unchanged. We conclude that with both these anaesthetic techniques the greatest changes in haemodynamic variables occurred shortly after induction, and that these changes were greater during general than spinal anaesthesia. The resection period was not associated with significant haemodynamic changes.

Aged↗
PubMed1994

Beta-adrenoceptor blockers in atrial fibrillation: the importance of partial agonist activity.

1. The ideal drug treatment for atrial fibrillation will control resting heart rate, blunt exercise induced tachycardia whilst not exacerbating nocturnal bradycardia. Monotherapy with digoxin may not be ideal. We have compared the effect of combining digoxin (0.25 mg daily) with atenolol 50 mg and 100 mg or pindolol 5 mg twice daily and 15 mg twice daily in a cross-over randomised single-blind trial in eight symptomatic patients (six male; mean age 62 years) with poorly controlled atrial fibrillation. 2. Heart rate control was measured by 24 h ECG at baseline on digoxin therapy and after 2 weeks with each treatment. Symptom scores for breathlessness and palpitation were measured using visual analogue scales. 3. The addition of both beta-adrenoceptor blockers significantly reduced mean diurnal maximum heart rate from baseline (all P < 0.001 ANOVA). Atenolol at both doses caused a greater reduction than either dose of pindolol (P < 0.001 ANOVA). Nocturnal maximum heart rate was not significantly reduced from baseline by either beta-adrenoceptor blocker, but both doses of pindolol caused increases in nocturnal maximum heart rate compared with atenolol (P < 0.001 ANOVA). 4. Atenolol caused a reduction in diurnal minimum heart rate compared with baseline and caused a reduction in nocturnal minimum heart rate whereas pindolol caused an increase (P < 0.001 ANOVA). 5. Atenolol 100 mg caused longer nocturnal pauses compared with baseline but pindolol 15 mg twice daily reduced the number of nocturnal pauses > 1.5 s (P = 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Antagonists↗
PubMed1994

Combination diuretic treatment in severe heart failure: a randomised controlled trial.

OBJECTIVES: (a) To test the hypothesis that a fixed 3 day course of the combination of a thiazide and loop diuretic is as effective as more prolonged treatment in the management of severe resistant cardiac failure. (b) To compare two thiazide diuretics (bendrofluazide and metolazone) in combination with loop diuretics in the treatment of severe resistant cardiac failure. DESIGN: Randomised study with a 2 x 2 factorial design. SETTING: Provincial teaching hospital. PATIENTS: 33 consecutive patients (40 episodes) admitted with severe congestive cardiac failure (New York Heart Association class III or IV) unresponsive to intravenous loop diuretics for 48 hours. MAIN OUTCOME MEASURES: Change in daily weight and serum electrolytes and clinical improvement in heart failure. RESULTS: Diuresis was established during 37 of 40 episodes; of the rest two patients died in hospital. On 36 occasions improvement was sufficient to allow discharge from hospital. Median (range) maximal weight loss was -5.05 (-11.3 to 1.6) kg after the addition of bendrofluazide and -5.6 (-12.2 to 4.8) kg after the addition of metolazone (NS). Area under the body weight loss against time curves showed no significant difference between the two thiazide diuretics. Median (range) maximal weight loss after three days of treatment was -5.4 (-12.2 to 4.8) kg and -5.5 (-10.3 to 1) kg after a more prolonged course of median (range) 5.6 (1 to 13) days (NS). Area under the body weight loss time curves showed no significant difference between the two durations of treatment. Bendrofluazide was associated with fewer electrolyte disturbances. CONCLUSIONS: Bendrofluazide and metolazone were equally effective in establishing a diuresis in patients with severe congestive cardiac failure resistant to loop diuretics. A fixed three day course of the combination was as effective as a longer course.

Adolescent↗
PubMed1994

Auditing the British Medical Journal.

The purpose of this study was to audit the outcome in terms of change in practice of the published research from one volume of the British Medical Journal. All original papers and short reports from one Volume 296 of the British Medical Journal (BMJ) 1988 were read and classified into theoretical only, practical and theoretical and practical. Those papers with any practical message were reviewed by one of a panel of specialists in the subject of the paper to assess if the recommendation made by the paper had become common clinical practice. The results show that most papers originated from teaching centres and research institutes in the UK. Only 8% of main papers and 6% of short reports had a solely practical application, although a further 18% and 22% had practical elements. The majority of the recommendations aimed at changing practice were of relevance to hospital specialists rather than general practitioners (GPs). Of the papers with any practical implications 48% (12% of the total) of main papers and 41% (11% of the total) of short reports were considered to be current practice. The reasons why the papers failed to change practice are discussed. In conclusion, the majority of the original research papers published in the BMJ in 1988 were of a theoretical nature and only about 20% of papers made recommendations for a change in practice. About 50% of the recommendations are now current practice.

Attitude of Health Personnel↗
PubMed1993

Amlodipine in patients with angina uncontrolled by atenolol. A double blind placebo controlled cross over trial.

Dihydropyridine calcium antagonists are established second line treatment for angina uncontrolled by beta-adrenergic blockers. Amlodipine is a recently introduced, dihydropyridine with a long half life. In a double blind, placebo controlled, cross over trial we assessed the efficacy and safety of amlodipine in 20 patients with persistent angina despite treatment with atenolol. 17 male patients (mean age 58 y) completed the study. Two patients were withdrawn during placebo because of worsening angina and one withdrew whilst on amlodipine because of palpitations. Compared with baseline, amlodipine prolonged exercise time to S-T segment depression by a median of 12.5%; significantly more than was found with placebo (median 0%). The improvement in exercise time and time to angina also tended to be greater for amlodipine than placebo. GTN consumption, at a median of 1.3/week, was significantly less with amlodipine than placebo (2.8). Attacks of angina were also reduced. Standing systolic and diastolic blood pressures and sitting systolic blood pressure were lower with amlodipine than placebo. Heart rate did not change. There was no change in cardiac output (measured by doppler aortovelography) when amlodipine was added to atenolol. Holter monitor measurements of 24 h maximum and minimum heart rate, heart rate variation and extrasystole counts were the same for amlodipine and placebo. In conclusion, amlodipine is effective in patients with angina inadequately controlled by atenolol alone, and does not interfere with cardiac rhythm or function.

Aged↗
PubMed1993

Vasodilatory action of the calcium antagonist amlodipine on large and resistance pulmonary arteries from normoxic and chronically hypoxic rats.

1. Isolated rat aorta and pulmonary arteries were maximally precontracted with 100 mmol/l KCl, and the vasorelaxation due to the dihydropyridine calcium antagonist amlodipine was measured. The response of large pulmonary arteries (mean lumen diameter 983 microns) was directly compared with that of isolated pulmonary resistance vessels (mean lumen diameter 259 microns) from both normoxic animals and animals exposed to chronic hypoxia. 2. Amlodipine caused a significant relaxation of aorta (P < 0.001). A significant relaxation of large and resistance pulmonary arteries from both normoxic and chronically hypoxic animals was also demonstrated at all doses tested (P < 0.05) or less). 3. Amlodipine produced significantly more relaxation in pulmonary resistance vessels than in large pulmonary arteries from both normoxic and chronically hypoxic rats (P < 0.02). 4. The action of amlodipine was slow in onset and persistent in all vessels studied. In the pulmonary vessels from normoxic animals both the rate of onset and the magnitude of effect was proportional to the drug concentration (P < 0.001). 5. These results demonstrate that amlodipine is a potent inhibitor of KCl-induced contractions in rat pulmonary arteries with a preferential action in pulmonary resistance vessels.

Amlodipine↗