Atherogenesis and the arginine hypothesis.

In patients who have elevated levels of plasma ADMA, a relative deficiency of L-arginine has been found to contribute to the pathophysiology of athersclerosis, causing vasoconstriction, and accelerating atherogenesis. This finding--that there is a relative deficiency of L-arginine in atherosclerotic disease--is a breakthrough that will open new avenues of therapy.

Impact of a home-based walking and resistance training program on quality of life in patients with heart failure.

Patients with heart failure (HF) often have profound activity limitations and diminished quality of life (QOL) due to symptoms of dyspnea and fatigue. Although recent studies demonstrate positive physiologic and psychological benefits of low to moderate intensity, supervised, aerobic exercise training performed 3 to 5 days/ week for 20 to 40 minutes' duration, in a monitored setting, the efficacy of a home-based exercise program combining endurance and resistance exercise on symptoms and QOL, are unknown. This randomized controlled study examined the efficacy, safety, and adherence rates of a 3-month home-based combined walking and resistance exercise program on symptoms and QOL in 40 women and men aged 30 to 76 years with New York Heart Association class II to III HF. Baseline and 3-month evaluations consisted of a chronic HF questionnaire to assess symptoms and QOL and exercise capacity by symptom-limited treadmill exercise test with respiratory gas analysis. The exercise intervention improved fatigue (p = 0.02), emotional function (p = 0.01), and mastery (p = 0.04). Overall exercise adherence was excellent (90%) and there were no reported adverse events. A moderate intensity home-based combined walking and resistance program for patients with class II to III HF is safe and effective in reducing symptoms and improving QOL.

Perceptions of physical fitness in patients with heart failure.

This study examined the relationship between perceived physical condition and measured physical fitness and activity levels in 40 patients with moderate heart failure (HF). Self rated physical condition, physical activity, self efficacy, and quality of life were evaluated by self administered questionnaires. Functional capacity was examined by cardiopulmonary exercise testing and 6 minute walk test. We found that physical activity levels were low. Participation in moderate intensity recreational activity and physical fitness were associated with self efficacy. Perceived physical condition was associated with emotional well being and levels of energy and fatigue. We conclude that self efficacy may reflect physical condition and physical activity levels in this sample of HF patients and may be a simple indicator of physical ability. Because of the association between perceived physical condition and emotional well being, caution must be taken when using self reports of physical condition. Further study is needed to explore these relationships.

Differences in treatment of acute myocardial infarction by sex, age, and other factors (the Stanford Five-City Project).

This study examines the temporal trends in the use of angiography followed by revascularization procedures for acute myocardial infarction (AMI) in 2,021 hospitalized men and 995 women aged 30 to 74 years who participated in the Stanford Five-City Project during the years 1986 to 1992. Our sample included hospitalized patients who received a discharge diagnosis code of 410 through 414 and met study criteria for either a definite or possible AMI. Incident and recurrent infarctions occurring in the years 1986 through 1992 were included, but only the first event in this period for each patient. We performed stepwise multiple logistic regression analysis to determine the probability of: (1) receiving coronary angiography, (2) revascularization by either coronary bypass surgery or angioplasty among those with angiogram, and (3) thrombolytic therapy. Age, year of procedure, disease severity, and time between symptom onset and medical treatment were included as covariates. After adjustment of these factors, women were less likely than men to undergo angiography but were equally likely to undergo revascularization and thrombolysis. Hispanics and whites were equally likely to receive angiography and thrombolysis, but Hispanics were less likely than whites to undergo revascularization. Age and disease severity were inverse predictors of coronary angiography but not of revascularization. Age, severity, and delay time between onset of symptoms and medical therapy were inverse predictors of thrombolysis; delay time was significantly greater in women than in men and averaged > 6 hours in both sexes. The likelihood of receiving angiography, revascularization, and thrombolysis increased sharply over the study period.

Predictors of physical activity in patients with chronic heart failure secondary to either ischemic or idiopathic dilated cardiomyopathy.

To identify predictors of physical activity levels in patients with chronic heart failure, 43 patients, aged 33 to 91 years, who had well-compensated heart failure were asked to perform a symptom-limited exercise treadmill test and to complete activity logs for 2 consecutive days while wearing an ambulatory heart rate activity monitor. Activity logs included information on the type of activity, duration, rating of perceived exertion, symptoms experienced, and the intensity of symptoms. Subjects also completed the Duke Activity Status Index, a brief self-administered questionnaire that assesses physical functioning, and a self-efficacy for general activity questionnaire. Simultaneous multiple regression analysis was used to predict physical activity levels from a model that included: personal variables of physical fitness (peak oxygen consumption); knowledge, attitudes, and beliefs including self-efficacy for general activity, and rating of perceived exertion during daily activity; and environmental factors such as social support (marital status). The overall model explained 38% of the variance (p < 0.001). Self-efficacy (p = 0.015) was the strongest predictor of physical activity in this group. From this initial descriptive study, we conclude that self-efficacy is a better predictor of performance of physical activity than measures of physical fitness or rating of perceived exertion during activity. Additional studies are needed to examine other behavioral and physiologic mediators as well as behavioral strategies that may be used to increase participation in physical activity programs. Particularly promising are strategies to enhance self-efficacy for exercise.

Physiologic changes in heart failure--"What's new".

The physiologic changes that accompany heart failure are complex and evolve over time. Adaptations to an initial insult include both central (myocardial) and peripheral mechanisms that attempt to maintain adequate cardiac output at rest, as well as during increased metabolic demands such as exercise. Physiologic models provide insight into these complex changes and are necessary to design and evaluate the efficacy of pharmacologic and nonpharmacologic interventions. Recent advances in ventricular remodeling and changes in myocardial adrenergic receptors are presented as are alterations in vasodilatory response, skeletal muscle structure, function, and metabolism.

Sources of social support as predictors of exercise adherence in women and men ages 50 to 65 years.

Examines types of social support that best predicts adherence at different time points during a 1-year endurance exercise program in 269 women and men ages 50 to 65 years. Results indicate that social support had similar effects on exercise participation for women and men, and support specific to exercise was a better predictor of exercise adherence than general social support. A preference for receiving a lesser amount of initial support from exercise staff was the strongest social support-related predictor of exercise adherence during the initial 6 months of the program. Support currently received from family and friends and exercise staff at Month 6 was found to be the strongest predictor of adherence during Months 7 to 12. Format of exercise was also a strong predictor of exercise adherence with home-based programs related to greater adherence. Additionally, divorced nonsmokers appear to be at increased risk for poor early exercise adherence and should be targeted in interventions to promote exercise participation.

Long-term effects of varying intensities and formats of physical activity on participation rates, fitness, and lipoproteins in men and women aged 50 to 65 years.

BACKGROUND: Although exercise parameters such as intensity and format have been shown to influence exercise participation rates and physiological outcomes in the short term, few data are available evaluating their longer-term effects. The study objective was to determine the 2-year effects of differing intensities and formats of endurance exercise on exercise participation rates, fitness, and plasma HDL cholesterol levels among healthy older adults. METHODS AND RESULTS: Higher-intensity, group-based exercise training; higher-intensity, home-based exercise; and lower-intensity, home-based exercise were compared in a 2-year randomized trial. Participants were 149 men and 120 postmenopausal women 50 to 65 years of age who were sedentary and free of cardiovascular disease. Recruitment was achieved through a random digit-dial community telephone survey and media promotion. All exercise occurred in community settings. For higher-intensity exercise training, three 40-minute endurance training sessions per week were prescribed at 73% to 88% of peak treadmill heart rate. For lower-intensity exercise, five 30-minute endurance training sessions per week were prescribed at 60% to 73% of peak treadmill heart rate. Treadmill exercise performance, lipoprotein levels and other heart disease risk factors, and exercise adherence were evaluated at baseline and across the 2-year period. Treadmill exercise test performance improved for all three training conditions during year 1 and was successfully maintained during year 2, particularly for subjects in the higher-intensity, home-based condition. Subjects in that condition also showed the greatest year 2 exercise adherence rates (P < .003). Although no significant increases in HDL cholesterol were observed during year 1, by the end of year 2 subjects in the two home-based training conditions showed small but significant HDL cholesterol increases over baseline (P < .01). The increases were particularly pronounced for subjects in the lower-intensity condition, whose exercise prescription required more frequent exercise sessions per week. For all exercise conditions, increases in HDL cholesterol were associated with decreases in waist-to-hip ratio in both men and women (P < .04). CONCLUSIONS: While older adults can benefit from initiating a regular regimen of moderate-intensity exercise in terms of improved fitness levels and small improvements in HDL cholesterol levels, the time frame needed to achieve HDL cholesterol change (2 years) may be longer than that reported previously for younger populations. Frequency of participation may be particularly important for achieving such changes. Supervised home-based exercise regimens represent a safe, attractive alternative for achieving sustained participation.

Ambulatory blood pressure and heart rate responses to the stress of work and caregiving in older women.

BACKGROUND: Although the informal caregiving role is associated with a range of stressors that are both chronic and severe, little is known concerning the acute physical and psychological effects of caregiving in the natural setting. This study evaluated the hemodynamic and psychological responses of five women identified as family caregivers who also worked outside the home and five matched working noncaregivers. METHODS: Subjects wore an ambulatory blood pressure monitor that recorded blood pressure and heart rate on an hourly basis throughout a one- to two-day period. They also completed hourly logs evaluating psychological, physical, and health-related variables through use of a preprogrammed pocket computer. Within- and between-group responses were compared in clinical, work, and postwork settings. RESULTS: Caregivers and noncaregivers showed comparable ambulatory blood pressure levels in the clinic and work settings. However, in contrast to noncaregivers, who showed the expected decrease in blood pressure level upon leaving the work setting (p values < .03), caregivers demonstrated a significant increase in systolic blood pressure levels following work when they were in the presence of the care recipient (p < .0002). The differences observed in blood pressure responses between the two groups were similarly reflected in the patterns of affective response recorded in the work and postwork settings. CONCLUSIONS: The results provide initial evidence of the acute iatrogenic effects of caregiving on physiological as well as psychological response systems.

Daily physical activity levels in congestive heart failure.

To determine the level of daily physical activity routinely performed by patients with congestive heart failure (CHF) and the ability of clinical and laboratory assessments of function to predict peak daily activity levels, 45 patients with CHF were evaluated in the laboratory and during 2 days of usual activity. Subjects performed symptom-limited treadmill exercise tests with respiratory gas analysis and wore a Vitalog activity monitor with continuous measurement of heart rate and body motion. Mean maximal oxygen uptake for this sample was 16.8 ml/kg/min. Peak daily physical activity involved walking on a flat surface (44%), or general activities (housework/yardwork, 42%). Most subjects were asymptomatic (49%) during daily physical activity, 22% noted dyspnea, 16% fatigue and 13% sore muscles/joints. Perceived intensity of peak daily physical activity (mean = 4.19, SD = 2.21) was similar to perceived exertion (mean = 3.73, SD = 1.37) reported at ventilatory threshold measured during treadmill exercise testing. Subjects may control their peak daily physical activity to minimize symptoms experienced. It was further observed that current methods of assessing functional capacity in these patients were inadequate for estimating the peak level of daily activity. In conclusion, daily physical activity levels are low in patients with congestive heart failure and a gap exists between exercise capacity and actual performance of daily physical activity.