Enhanced endothelial vasoreactivity in endurance-trained older men.

Using external vascular ultrasound, we measured brachial artery diameter (Diam) at rest, after release of 4 min of limb ischemia, i. e., endothelium-dependent dilation (EDD), and after sublingual nitroglycerin, i.e., non-endothelium-dependent dilation (NonEDD), in 35 healthy men aged 61-83 yr: 12 endurance athletes (A) and 23 controls (C). As anticipated, treadmill exercise maximal oxygen consumption (VO(2 max)) was significantly higher in A than in C (40. 2 +/- 6.6 vs. 27.9 +/- 3.8 ml. kg(-1). min(-1); respectively, P < 0. 0001). With regard to arterial physiology, A had greater EDD (8.9 +/- 4.2 vs. 5.7 +/- 3.5%; P = 0.02) and a tendency for higher NonEDD (13.9 +/- 6.7 vs. 9.7 +/- 4.2%; P = 0.07) compared with C. By multiple linear regression analysis in the combined sample of older men, only baseline Diam (beta = -2.0, where beta is the regression coefficient; P = 0.005) and VO(2 max) (beta = 0.23; P = 0.003) were independent predictors of EDD; similarly, only Diam (beta = -4.0; P = 0.003) and VO(2 max) (beta = 0.27; P = 0.01) predicted NonEDD. Thus endurance-trained older men demonstrate both augmented EDD and NonEDD, consistent with a generalized enhanced vasodilator responsiveness, compared with their sedentary age peers.

Acute reduction in ankle/brachial index following smoking in chronic smokers with peripheral arterial occlusive disease.

The ankle-brachial systolic pressure index (ABI), a noninvasive measure of peripheral arterial occlusive disease (PAOD) severity, is considered a marker of atherosclerosis and an independent predictor of mortality. However, it is not known whether factors other than PAOD severity, such as cigarette smoking, have an effect on ABI measurement. Therefore, the authors examined the acute effects of cigarette smoking on ABI and the peripheral circulation in 10 older (63 +/- 10 years) chronic smokers (39 +/- 37 pack-years) with PAOD (ABI=0.64 +/- 0.14). The patients were instructed to refrain from smoking and from consuming caffeine-containing beverages for at least 12 hours before the tests. The patients were randomly assigned to 2 days of testing consisting of a nonsmoking and a smoking day. Resting heart rate, blood pressure, ABI, and calf blood flow by plethysmography were obtained on both testing days. The smoking day consisted of smoking two filter cigarettes over a period of 10 minutes before the measurement of ABI and calf blood flow. The ABI on the smoking day (0.55 +/- 0.11) was lower (p=0.008) than on the nonsmoking day (0.64 +/- 0.14) owing to a lower (p=0.020) ankle systolic blood pressure (81 +/- 28 vs 93 +/- 28 mmHg). Brachial systolic blood pressures, heart rate, and calf blood flow were not altered by smoking (p>0.05). These results demonstrate that the acute effect of cigarette smoking lowers the ABI in chronic smokers with intermittent claudication, thereby yielding evidence of a transient deleterious effect of cigarette smoking on the peripheral circulation in chronic smokers.

Endothelial reactivity and cardiac risk factors in older patients with peripheral arterial disease.

Peripheral arterial disease (PAD) is a major cause of morbidity and mortality. Endothelium-dependent vasoreactivity, which is advocated as a measure of vascular health, is impaired in persons with cardiac risk factors and coronary artery disease. Few studies have examined the degree of endothelial dysfunction in patients with PAD. Using high-resolution external vascular ultrasound, we measured brachial artery diameter and flow at rest, and in response to reactive hyperemia (flow-mediated dilation) in 50 older patients (age 69 +/- 1 year) with PAD (ankle-to-brachial artery index of 0.67 +/- 0.03), and 50 age-matched non-PAD patients. Coronary artery disease was more prevalent in PAD than in non-PAD patients (40% vs 4%, p <0.001). Systolic blood pressure (153 +/- 4 vs 141 +/- 3 mm Hg, p <0.01), fasting glucose (129 +/- 6 vs 109 +/- 5 mg/dl, p <0.001), and pack-years smoked (54 +/- 7 vs 25 +/- 3, p <0.01) were higher in the PAD than in non-PAD patients. There were no differences in baseline brachial artery diameter, blood velocity, or flow between the 2 groups. However, the 1-minute postocclusion percent change in diameter (6.5 +/- 0.7% vs 9.8 +/- 0.7%, p <0.001) and the change in diameter (0.22 +/- 0.02 vs 0.33 +/- 0.02 mm, p <0.001) were lower in PAD than in non-PAD patients, suggesting impaired endothelium-dependent dilation. The postocclusion hyperemic velocity and blood flow were also lower in PAD than in non-PAD patients. In multiple regression analyses the low-density lipoprotein-to-high-density lipoprotein cholesterol ratio, elevated fasting glucose, and high systolic blood pressure were independent predictors of percent change in brachial artery diameter (r2 = 0.37, p <0.001). Thus, older patients with PAD had impaired endothelial dependent vasodilation compared with controls that was associated with the presence of cardiac risk factors. The effect of cardiac risk factor intervention on endothelial function in patients with PAD remains to be determined.

Characteristics of acquired immunodeficiency syndrome in older adults.

OBJECTIVE: To examine demographic and clinical features of older AIDS patients in comparison with younger individuals. DESIGN: Data base review. SETTING: Maryland AIDS Registry from 1981 through the end of 1994. PARTICIPANTS: All registered Maryland AIDS cases greater than or equal to 60 years of age at diagnosis and all Maryland AIDS cases aged 20 to 39. MAIN OUTCOME MEASURES: Demographic features, mode of transmission and change in mode over time, clinical presentations, CD4+ counts, and survival time. RESULTS: A total of 321 (2.7%) AIDS cases diagnosed in Maryland were people 60 years of age or older compared with 7511 cases (63.9%) in people aged 20 to 39 years. The proportion of whites was higher in the older group, but the gender distribution was similar to younger counterparts. Transfusion was the primary cause of exposure of 32% of the older people with AIDS; however, during the last few years, sexual transmission and drug abuse have been implicated more frequently. Twelve percent of older patients had no reported risk factors compared with 4% of younger AIDS patients. The most common presenting AIDS indicator disease in older cases was Pneumocystis carinii pneumonia. Wasting syndrome, candidiasis, and HIV encephalopathy also occurred frequently. Median life span was 9 months compared with 22 months in the young. CONCLUSION: Our study demonstrates that transfusion is no longer the leading cause of AIDS in older people in Maryland. The relatively increased prominence of transmission by other modes in this age group raises the importance of preventive and educational measures. Older patients generally have a shorter survival than younger individuals.

Heart rate variability and cardiovascular fitness in senior athletes.

To determine if the age-associated decline in heart rate variability is due in part to decreases in fitness levels, we compared heart rate variability parameters in older athletes and age-matched sedentary persons. All heart rate variability parameters were superior in the athletes, consistent with an enhanced cardiac vagal modulation in the athlete.

Improved walking economy in patients with peripheral arterial occlusive disease.

The effect of exercise rehabilitation on the oxygen cost of ambulation in patients with peripheral arterial occlusive disease (PAOD) was evaluated with specific emphasis on the effects of exercise rehabilitation on the slow component of VO2. Because the slow component of VO2 represents an increase in VO2 despite constant-intensity exercise, it can profoundly affect the relative energy cost of exercise in individuals with a low functional capacity. Twenty-six patients with intermittent claudication performed treadmill walking at 2.0 mph/0% grade for 20 min or until maximal claudication pain before and after 4 months of rehabilitation. The slow component of VO2 during the treadmill test was defined as the difference between the end-exercise VO2 and the VO2 observed at minute 3. Ankle/brachial systolic pressure index (ABI) was measured before and immediately following the exercise test. Rehabilitation consisted of 3 d x wk(-1) of treadmill walking for 15-30 min at 60-70% of VO2peak. The slow component of VO2 and end-exercise VO2 at pretraining (0.75 +/- 0.90 and 11.12 +/- 2.10 mL x kg[-1] x min[-1]) were significantly reduced after 4 months of exercise rehabilitation (-0.07 +/- 1.11 and 10.07 +/- 1.80 mL x kg[-1] x min[-1]; P < 0.05). Exercise rehabilitation also significantly (P < 0.05) increased the post-exercise ABI (pre-rehabilitation = 0.36 +/- 0.26, post-rehabilitation = 0.43 +/- 0.25). These data suggest that 4 months of exercise rehabilitation: 1) improves walking economy in PAOD patients because of a decreased slow component of VO2, and 2) increases post-exercise ABI.

Low-velocity graded treadmill stress testing in hemiparetic stroke patients.

BACKGROUND AND PURPOSE: Coronary artery disease is prevalent in stroke patients and is an important factor affecting rehabilitation and health outcomes. However, the presence of neurological deficits in gait and balance has discouraged systematic application of exercise testing and prescription in the stroke population. We evaluated a novel graded treadmill stress test in paretic stroke patients and tested floor walking as a predictor of adequate neurological function to perform the treadmill test. METHODS: Patients (n = 31) with residual paretic gait deficits after ischemic stroke were evaluated with graded treadmill at gait velocities individualized to functional mobility observed during an initial zero-incline treadmill tolerance test. RESULTS: Most patients (30/31) tolerated testing, achieving mean heart rates of 129 +/- 14 beats per minute (mean +/- SD), representing 84 +/- 10% of maximal age-predicted heart rate. Evidence for asymptomatic myocardial ischemia was found in 29% of those without known coronary artery disease. Exercise termination was more often due to generalized fatigue than cardiopulmonary intolerance (23/31 versus 4/31; P < .0001) or hemiparetic leg fatigue (1/31; P < .0001). Floor walking across a wide range of velocities (0.25 to 2.5 mph) demonstrated a strong linear relation with treadmill velocities (n = 24; r = 80; P < .0001); all patients floor walking at > or = 0.5 mph had adequate neuromotor function to perform the exercise test. CONCLUSIONS: These findings suggest that graded treadmill exercise testing, with proper safety precautions, can be used to assess cardiopulmonary function in paretic stroke patients. A simple floor-walking test predicts adequate neurological function to perform the exercise test. Exercise capacity is most limited by generalized fatigue and not by the paretic limb, supporting a rationale for endurance training in this population.

Relationship of body composition and cardiovascular fitness to lipoprotein lipid profiles in master athletes and sedentary men.

A number of studies demonstrate that highly conditioned older athletes are leaner than their sedentary counterparts, and have lipoprotein profiles similar to that of young individuals. It is not clear whether the high maximal aerobic capacity (VO2max) or lean body habitus is the major determinant of the favorable lipoprotein lipid profiles present in older athletes. The objective of this study was to determine whether body composition or VO2max was the major determinant of lipoprotein lipid profiles among 61 master (age 63 +/- 6 years, mean +/- SD) athletes (VO2max > 40 mL/kg/min), 39 age-matched lean (% body fat < 25%), and 51 obese (% body fat > 25%) sedentary men. Plasma high density lipoprotein cholesterol (HDL-C) concentrations were 25% higher in that athletes than in the lean sedentary men, and 42% higher than in the obese sedentary men. Triglyceride (TG) concentrations were 24% lower in the master athletes than in the lean sedentary men, and 51% lower than in the obese sedentary group. Plasma low density lipoprotein cholesterol (LDL-C) levels were 9% lower in the athletes than in the other groups of sedentary individuals. In stepwise multiple regression analysis the percent body fat was the major independent predictor of HDL-C and TG levels accounting for 29% and 41% of the variation in these levels, respectively. The VO2max accounted for an additional 6% of the variance in HDL-C levels and 2% of the variance in TG levels. These cross-sectional results suggest that the favorable lipoprotein profile of master athletes is largely due to their lean body habitus, with a small independent contribution from their higher levels of cardiovascular fitness. Thus, regular vigorous aerobic exercise and maintenance of low body fat may prevent the commonly observed age-associated deterioration in lipoprotein concentrations.

Oxygen uptake during constant-intensity exercise in patients with peripheral arterial occlusive disease.

The purpose of the present study was to evaluate the oxygen uptake (VO2) response to walking in patients with peripheral arterial occlusive disease (PAOD) at a constant velocity and to determine whether the oxygen uptake observed during constant-intensity exercise in this population is associated with the severity of PAOD. Forty-nine PAOD patients with intermittent claudication were recruited (values are mean +/- SD) [age = 66.4 +/- 8.0 years, weight = 83.3 +/- 16.0 kg, body mass index = 28.8 +/- 5.6, ankle/brachial systolic blood pressure index (ABI) = 0.63 +/- 0.18, VO2peak = 13.02 +/- 2.99 ml/kg/min]. Patients were evaluated during a 2.0 miles/h walk on a treadmill until maximal claudication pain or for a maximum of 20 minutes. On average, patients walked for a duration of 10.3 +/- 5.8 min. Despite the constant absolute intensity during the exercise bout, there was a significant (p < 0.01) 4.0% increase in VO2 from min 3 of exercise (10.58 +/- 2.02 ml/kg/min) to min 5 (11.01 +/- 2.18 ml/kg/min) and a further 4.0% increase from min 5 to the end of exercise (11.46 +/- 2.32 ml/kg/min). Expressed as relative exercise intensity, this represented an increase from 80.8 +/- 18.3% to 87.1 +/- 18.0% of VO2peak from min 3 to the end of exercise. The magnitude of increase in VO2 during the exercise bout was not correlated with resting ABI (r = 0.00, p = 0.68) or post-exercise ABI (r = 0.04, p = 0.73). There was a nonsignificant trend towards a correlation between the time to onset of claudication pain and the magnitude of increase in VO2 (r = 0.25, p = 0.08). Results of this study suggest that an increase in VO2 occurs during constant-velocity walking at a high relative intensity in PAOD patients. This increase in VO2 does not appear to be related to the severity of PAOD.

Comparison of heart rate variability in patients with chronic fatigue syndrome and controls.

Recent studies have reported a close association between chronic fatigue syndrome and neurally mediated hypotension. We hypothesized that this association may result from an abnormality in autonomic function among patients with chronic fatigue syndrome, which may be detectable using an analysis of heart rate variability. We prospectively studied 19 patients who fulfilled the Centers for Disease Control criteria for chronic fatigue syndrome and 11 controls. Each subject underwent a two-stage tilt-table test while wearing a Holter monitor. Heart rate variability was assessed in the supine baseline position and during upright tilt using frequency domain parameters. In the baseline supine position, high frequency (HF) power, low frequency (LF) power, and the ratio of low frequency power to high frequency power (LF/HF ratio) were similar. In both patient groups, upright tilt resulted in a similar decrease in HF power, increase in LF power, and increase in the LH/HF ratio. In conclusion, autonomic function, as assessed using an analysis of heart rate variability, does not differ in the baseline supine state, nor in response to upright tilt among patients with chronic fatigue syndrome and healthy controls.