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Biomedical subjects

G F Fletcher

Publications and source records attributed to G F Fletcher.

At least 19 recordsLinked to original sources
PubMed1991

Blood magnesium and potassium alterations with maximal treadmill exercise testing: effects of beta-adrenergic blockade.

To test alterations in plasma potassium and magnesium levels with maximal exercise, 15 sedentary, healthy men (mean age 29 years) participated in a double-blind crossover study for 11 weeks with propranolol, atenolol, and placebo. Maximal exercise tests were done at baseline and after placebo and beta-blockade phases. Blood for analysis was collected via indwelling brachial vein angiocatheters at baseline and during and after testing. Plasma potassium and magnesium levels increased at peak exercise with atenolol, propranolol, and placebo. There was no difference among groups in baseline recovery for magnesium (mean 28 minutes, range 24 to 30 minutes). Potassium levels returned to baseline more rapidly (compared with magnesium) in the placebo and atenolol groups (mean 10 minutes); however, recovery time was prolonged with propranolol (26 minutes) compared with placebo and atenolol (p less than 0.01). In conclusion, plasma magnesium and potassium levels increased significantly with maximal exercise and are unaffected by atenolol or propranolol beta-blockade. Propranolol, however (compared with atenolol and placebo), prolongs the time of return to baseline of plasma potassium after exercise.

Adrenergic beta-Antagonists↗
PubMed1991

Efficacy and compliance with cholestyramine bar versus powder in the treatment of hyperlipidemia.

PURPOSE: The purpose of the study was to compare the powder and the bar forms of cholestyramine to determine efficacy and patient compliance. SUBJECTS AND METHODS: A prospective, randomized trial was conducted that included 83 healthy men and women with hyperlipidemia greater than the 90th percentile for low-density lipoprotein (LDL) or total cholesterol. Patients were randomly assigned to receive either cholestyramine powder, two packets (8 g), twice daily, or cholestyramine confectionery bar, in maple or mint flavors, two bars (8 g), twice daily. Fasting serum total cholesterol, LDL cholesterol, high-density lipoprotein (HDL) cholesterol, and triglycerides were measured at baseline, after 6 to 8 weeks of following the American Heart Association Step I diet alone, and after 8 weeks of taking either the cholestyramine bar or powder. RESULTS: Total cholesterol decreased significantly (p less than 0.01) by 16% in the bar group and 17% in the powder group. LDL cholesterol decreased by 28% and 29% in the bar and powder groups, respectively (p less than 0.01). There was no significant change in HDL cholesterol. Triglycerides increased in both groups, by 29% in the bar group and by 25% in the powder group. There was no difference between bar and powder in the effect on blood lipids. The majority of the lipid-lowering effect was seen within 14 days. Mean patient endpoint compliance with the therapy was 91.8 +/- 3.6% in the bar group and 94.8 +/- 2.1% in the powder group. There was no difference between groups. CONCLUSION: The cholestyramine confectionery bar is as effective as cholestyramine powder in the treatment of hyperlipidemia. The majority of the lipid-lowering effect is seen within 14 days of therapy. Although patient compliance is comparable between the two forms, gastrointestinal side effects were slightly greater with the bar form. Therefore, although the bar offers an alternative form of therapy, there appears to be no advantage with regard to patient compliance or palatability.

Adult↗
PubMed1990

Effects of exercise testing, training and beta blockade on serum potassium in normal subjects.

To evaluate the effects of exercise testing, training and beta blockade on serum potassium, 40 normal subjects (24 men, 16 women, mean age 33 years) had 4 maximal exercise tests with venipuncture for serum potassium before and less than or equal to 40 seconds after each test. After initial exercise testing, they were randomized to atenolol 50 mg daily, atenolol 100 mg daily, propranolol 80 mg twice daily or placebo. All began a 9-week dynamic exercise program for 8 weeks followed by a 1-week drug-free washout period. Tests were done after weeks 1, 8 and 9. A significant mean increase (p less than 0.05) in serum potassium occurred with maximal exercise in the atenolol 50 mg and propranolol groups after 1 week of treatment (mean +/- standard deviation, 4.78 +/- 0.29 to 5.09 +/- 0.43 mEq/liter and 4.81 +/- 0.55 to 5.30 +/- 0.33 mEq/liter). By week 8 after training, all beta blockade groups showed an increase in postmaximal exercise test serum potassium (atenolol 50 mg, 4.78 +/- 0.29 to 5.11 +/- 0.26 mEq/liter; atenolol 100 mg, 4.95 +/- 0.41 to 5.16 +/- 0.36 mEq/liter; propranolol, 4.81 +/- 0.55 to 5.05 +/- 0.29 mEq/liter). After washout, only the placebo group showed an increase in postmaximal test serum potassium (4.99 +/- 0.46 to 5.35 +/- 0.27 mEq/liter). Data indicate that hyperkalemia with maximal exercise testing increases after training with atenolol and propranolol compared to placebo and that this effect resolves once treatment is discontinued.

Adult↗
PubMed1989

Exercise testing and training with beta-adrenergic blockade: role of the drug washout period in "unmasking" a training effect.

To determine whether or not a training effect can be achieved with beta-adrenergic blockade and whether there is a difference between selective and nonselective therapy, we recruited 40 healthy subjects (16 women, 24 men) to participate in a 9-week exercise training program. After a baseline exercise treadmill test, subjects were randomized to oral therapy groups of atenolol, 50 mg daily (AT 50), atenolol, 100 mg daily (AT 100), propranolol, 80 mg twice a day (Prop), or placebo. Repeat exercise tests were performed at week 1, week 8, and at week 9, with week 8 to 9 being a 1-week drug-free washout period. At week 8, maximal oxygen consumption (Max VO2), when compared with baseline levels, was increased slightly in AT 50 (4.2%) and Prop (2.4%), decreased in AT 100 (5.3%), and increased significantly in the placebo group (12.7%). After washout, Max VO2 increased significantly compared with baseline in AT 50, AT 100, and Prop (9.8%, 10.8%, and 9.8%, respectively). We conclude that there is no significant difference between selective and nonselective beta-blockade therapy in the development of a training effect. This effect, however, may not become apparent until the drug is withdrawn.

Adrenergic beta-Antagonists↗
PubMed1988

Exercise testing in patients with musculoskeletal handicaps.

To determine safe and effective exercise testing techniques for musculoskeletally handicapped individuals, 20 patients (mean age, 61 years) were studied. Types of handicaps included various degrees of paralysis of arms and legs, and leg amputations. Seventeen of the 20 patients had concurrent cardiovascular problems. All were currently hospitalized, engaged in various physical therapy exercises, and referred for exercise testing to increase rehabilitation therapy or for cardiovascular evaluation. Of 20 tests, arm ergometry was used in 15, leg or combination arm-leg ergometry in four, and treadmill in one. All patients completed testing with mean increases in heart rate (82 to 106 bpm arm, 88 to 125 other) and systolic blood pressure (114 to 127 mmHg arm, 118 to 146 other). Low-grade atrial and ventricular ectopy occurred in eight patients, decrease or plateauing of systolic blood pressure in three, increased diastolic blood pressure in two, and significant (greater than or equal to 1mm) ECG S-T segment displacement in one. With the use of appropriate equipment for each patient, exercise testing can be done safely and effectively in musculoskeletally handicapped individuals.

Adult↗
PubMed1988

Outpatient rehabilitative training in patients with cardiovascular disease: emphasis on training method.

As our ability to evaluate cardiovascular patients expands and direct oxygen consumption measurements are available, exercise prescriptions can be better individualized for each patient. By using basic principles of frequency and duration and specifically basing intensity and progression on percent of maximum oxygen consumption, protocols using various modes of exercise may be defined so that each patient entering cardiovascular training programs will gradually progress. This methodology discussion presents concise progressions for both phase II monitored and phase II nonmonitored medically supervised exercise training. The phase II monitored protocol consists of levels 1 through 6 and is designed to be completed within a minimum of six 1-hour sessions. The phase II nonmonitored protocol consists of levels 7 through 12 and is designed to be completed within 12 weeks. The ultimate goal is for each patient to safely progress to a training level that can be maintained safely and effectively by the patient. A total of 192 patients enrolled in our phase II programs have safely completed both components and are in long-term maintenance programs.

Cardiac Rehabilitation↗
PubMed1986

Phase II intensive monitored cardiac rehabilitation for coronary artery disease and coronary risk factors--a six-session protocol.

To evaluate phase II intensive monitored cardiac rehabilitation using a 6-level, 6-session protocol, 31 patients were placed in a progressive 6-level exercise protocol with careful supervision and assessment of heart rate, rhythm, blood pressure and perceived exertion. Duration after the cardiac event ranged from 12 days to 8 years (median 10 months). Each exercise prescription was based on exercise testing with oxygen consumption determinations. Exercise activities were individually prescribed according to percentages of maximal MET level achieved on the exercise test. Each exercise session incorporated calisthenics, treadmill exercise, and bicycle and arm ergometry with progressively greater workloads on the various stations. All patients completed the 6 levels within 6 sessions of approximately 1 hour each, and achieved their designated 50 to 75% target heart rate with perceived exertion level 13 or less. There were no critical cardiac events, i.e., high-grade ventricular arrhythmias or myocardial infarction. All completed the 6-level protocol and progressed to a nonmonitored exercise program with no difficulty. The results of this short-term method of telemetry-monitored rehabilitation suggest benefits of proper exercise instruction, successful achievement of the 50 to 75% exercise target heart rate, detection of minor new arrhythmias and alterations of blood pressure response, adequate use of the perceived exertion scale, and a safe and effective transition to subsequent exercise programs.

Adult↗
PubMed1986

Community phase of cardiac rehabilitation.

Although their effects cannot be shown to statistically alter coronary heart disease mortality or morbidity, voluntary health organizations throughout the world clearly play an important role in bringing about favorable changes in the natural history of this disease and in the community phase of its management. In particular, voluntary organizations are able to conduct research surveys and field trials and by so doing favorably influence state health administration. They are able to correct temporary deficiencies in health services, particularly in the form of psychosocial support and cardiac health education. Observers note that the major change in community phase management has occurred with the wider use of coronary bypass surgery since 1975. More objective data, especially relating to psychosocial factors, can be expected when further research (especially the MONICA Study) is completed. Throughout the world, however, existing voluntary health organizations could be more active in the community phase of cardiac rehabilitation. It would seem an area where such organizations could well do more. A challenging question that should be constantly reviewed is 'Can we do more to reduce the effects of invalidism in cardiac patients?'

Australia↗
PubMed1986

Rehabilitation after coronary angioplasty--is it effective?

To determine the effects of cardiac rehabilitation following coronary angioplasty, 30 patients were evaluated by telephone questionnaire following discharge from a cardiac rehabilitation program. Angioplasty educational booklets and fat-controlled dietary instruction were provided for all 30 patients; however, the diet was actually implemented by only 11. Activities of daily living and home physical exercise guidelines were provided for 24 of the 30 subjects. Outpatient follow-up questionnaire within six months after discharge revealed 14 of 30 working full-time, 18 of 30 on fat-controlled diet, 16 of 30 regularly exercising, and 18 of 30 not smoking. Anginal chest discomfort warranting physician evaluation had developed in 11 of the 30. We identified the following problems in our cardiac rehabilitation program for angioplasty patients: no advance starting notice to rehabilitation team, short hospitalization (mean 4.9 days), little family unit instruction, and physicians ordering a regular diet when a special one was indicated. We conclude that our program of inpatient cardiac rehabilitation following angioplasty is not effective in altering patient behavior with regard to fat-controlled diet, exercise habits, and smoking habits, and that symptoms of angina pectoris requiring physician evaluation are common in these patients.

Adult↗
PubMed1985

Exercise training during chronic beta blockade in cardiovascular disease.

To determine whether cardioselective and nonselective beta-blocking agents impair exercise training effects in patients with cardiovascular disease, 50 subjects were evaluated. All were in a 3-times-weekly medically supervised outpatient exercise program for 3 months or longer. Treadmill exercise tests were done initially and at 3-month intervals. Eight patients were receiving atenolol, 23 propranolol, 3 timolol, 6 metoprolol, and 8 nadolol and 1 patient receiving timolol changed to atenolol and 1 receiving nadolol changed to propranolol. Treadmill test duration increased significantly (p less than 0.05), from 7.5 +/- 2.5 to 9.9 +/- 2.3 minutes, with exercise training. In 35 of the 50 subjects heart rate at rest decreased significantly (p less than 0.05) from 67.5 +/- 11.7 to 60.4 +/- 10.5 beats/min. The other 15 subjects were excluded from heart rate analysis because beta blockade was begun 1 to 2 weeks after the initial exercise test. It is concluded that exercise training effects (increase in exercise test duration and decrease in resting heart rate) can be achieved in patients with cardiovascular disease in the presence of both cardioselective and nonselective beta-blocking agents.

Adrenergic beta-Antagonists↗
PubMed1984

Telephonically-monitored home exercise early after coronary artery bypass surgery.

To evaluate the usefulness of telephonically-monitored home exercise in patients within two weeks postcoronary bypass surgery, we randomly enrolled 46 male patients in a 12-week home program of either short walks or bicycle ergometry. Home exercise was done five times weekly and monitored both before and immediately after three times weekly. New arrhythmias or conduction disturbances were detected in 18 of 23 (78 percent) of the bicycle group and in 20 of 23 (87 percent) of the short walk patients. New symptoms developed in three patients, two from the short walk group and one from the bicycle group. Two bikers and one walker developed elevated blood pressure; all were referred to physicians and were successfully managed. Electrocardiographic abnormalities led directly to diagnostic and therapeutic intervention in nine of the 46 patients-four bikers and five walkers. There were no complications such as ventricular tachycardia or ventricular fibrillation. Technically clear telephone rhythm strips were obtained from patients calling both locally and long distance.

Arrhythmias, Cardiac↗