Effects of cardiac rehabilitation and exercise training on autonomic regulation in patients with coronary artery disease

Impact of aging on hostility in coronary patients and effects of cardiac rehabilitation and exercise training in elderly persons

Hostility is a coronary artery disease (CAD) risk factor affecting recovery after major CAD events. Yet, few data exist on the impact of aging on hostility in CAD patients or the effects of cardiac rehabilitation on elderly patients with high hostility. The authors studied 500 consecutive patients following CAD events to determine the impact of aging on hostility scores, the prevalence of hostility symptoms, and the response of elderly persons with hostility symptoms to cardiac rehabilitation programs. Overall hostility scores (p<0.01) and prevalence of hostility symptoms (8% in 268 elderly vs. 28% in 81 younger patients [aged <50 years]) were inversely related to age (p<0.01). Elderly persons with hostility symptoms had greater weight (p=0.02), four times higher anxiety and depression scores (p<0.0001), two times higher scores for somatization (p<0.0001), and 17% lower scores for quality of life (p<0.001) compared with elderly persons without hostility symptoms. Marked reduction in hostility and improvements in other risk factors occurred following rehabilitation. These results demonstrate the inverse relationship between age and hostility symptoms in patients with CAD. Although hostility symptoms are relatively uncommon in elderly persons with CAD, these patients have more adverse CAD risk profiles and still have marked improvements following cardiac rehabilitation and exercise training programs.

Altered profile of baroreflex and autonomic responses to lower body negative pressure in chronic orthostatic intolerance

BACKGROUND

Chronic orthostatic intolerance (COI) is a common and disabling autonomic syndrome of unclear pathophysiology. We tested the hypothesis that baroreflex and autonomic responses to graded lower body suction (LBNP, up to -40 mmHg) could be altered in COI patients.

METHODS

Electrocardiogram (ECG), non-invasive arterial blood pressure and respiratory activity were measured during progressive LBNP (seven patients and seven volunteers). Lumped arterial baroreflex sensitivity (alpha index), and its arterial and cardiopulmonary components, were assessed by multivariate closed-loop analysis of RR interval and systolic arterial pressure (SAP) spontaneous variabilities and respiration. Monovariate spectral analysis of RR interval and SAP variability provided markers of autonomic regulation of the sinoatrial (SA) node and of vascular sympathetic modulation.

RESULTS

Similar reductions in overall and cardiopulmonary baroreflex gain were observed in both groups in response to graded LBNP. In contrast, only controls demonstrated a selective increase in arterial baroreflex sensitivity, at low-grade LBNP. Clear increases in the low-frequency component of RR interval variability (LFRR) [and decreases in the high-frequency component of RR interval variability (HFRR), both in normalized units] were observed in controls with graded LBNP, while insignificant changes occurred in COI patients, who showed, conversely, exaggerated sympathetic vasomotor responses [as assessed by the low frequency component of SAP variability (LFSAP)].

CONCLUSIONS

Patients with chronic orthostatic intolerance show distinct signs of altered baroreflex and autonomic regulation of the SA node and of the vasculature in response to graded LBNP.

Heart rate variability following coronary artery bypass graft surgery as a function of recovery time, posture, and exercise

This study examined the claim made by Niemela et al. (1992) that the decline in heart rate variability after coronary artery bypass graft surgery is irreversible. We tested six women and 16 men six and 12 weeks postoperative in three postures: in the supine position, in the standing position, and during low-intensity steady-state exercise. Beat-by-beat arterial blood pressure and electrocardiographic R–R interval data were collected continuously for 10 min in each condition. R–R interval data were analyzed with spectral analysis; baroreflex data were analyzed using the sequence method. Our results show that the indices of parasympathetic modulation improved over time, as seen by an | increased spontaneous baroreflex sensitivity and parasympathetic indicator, that both indices were affected by posture, and that spontaneous baroreflex sensitivity was also affected by low-intensity exercise. The effects of posture are consistent with attenuated responses of healthy older subjects to orthostatic stress. Similarly, the effects of low-intensity exercise are consistent with findings in healthy subjects. We found that spontaneous baroreflex sensitivity declined during exercise, whereas, in healthy subjects, this is maintained during low-intensity steady-state exercise. Our results of significant functional recovery between six and 12 weeks postoperative suggest that at least some of the autonomic dysfunction following surgery is temporary. Previously, no such duration of study has lasted longer than four or six weeks following cardiac surgery, which may not have been long enough to show significant functional restoration in heart rate variability.Key words: heart rate variability, spontaneous baroreflex sensitivity, CABG surgery, posture, exercise.

Men's cardiovascular and pulmonary health

Heart disease in men is declining steadily, but it remains the number one killer of men in the United States. CLRD, influenza/pneumonia, and lung cancer are three more causes of top 10 mortalities in men. Epidemiological and clinical studies conclude that CVD is largely preventable through lifestyle modification. CHD, COPD, occupational lung disease, and lung cancer are all preventable by primary prevention (ie, no cigarette smoking). All men should be counseled about the grave significance of heart and lung disease as a cause of illness and death, the importance of primary prevention, and the great variability in symptom presentation. Nurses are in the ideal position to educate patients, families, and colleagues about heart and lung disease.

Long-term combined beneficial effects of physical training and metabolic treatment on atherosclerosis in hypercholesterolemic mice

The pathogenic mechanisms by which physical exercise influences atherosclerotic lesion formation remain poorly understood. Because vigorous physical training increases oxidative stress, this study tested the hypothesis that graduated and moderate physical exercise together with metabolic intervention (l-arginine and antioxidants) may contribute to increased vascular protection. Exercise training in mice was induced by graduated swimming. In hypercholesterolemic male mice on an atherogenic high-cholesterol diet, graduated and moderate exercise lowered plasma cholesterol and decreased atherosclerotic lesions compared with sedentary control mice. Antioxidants (1.0% vitamin E added to the chow and 0.05% vitamin C added to the drinking water) and l-arginine (6% in drinking water) supplementation to exercising hypercholesterolemic mice further and synergistically reduced atherosclerosis compared with untreated exercised mice. Arterial oxidation-specific epitopes and systemic oxidative stress were reduced by metabolic intervention. Graduated chronic exercise elicited an increase in production of nitric oxide through increased endothelial nitric oxide synthase expression and ameliorated scavenger activities. Thus, metabolic intervention with l-arginine and antioxidants together with graduated and moderate exercise training reduce atherosclerotic lesion formation.

Prevalence of anxiety in coronary patients with improvement following cardiac rehabilitation and exercise training

Numerous studies have indicated that psychological distress, including anxiety, is a significant risk factor for coronary artery disease (CAD). We studied 500 consecutive patients after recent CAD events and demonstrated a very high prevalence of generalized anxiety and moderate to severe anxiety symptoms, particularly in younger patients. In addition, our data demonstrate the abnormal CAD risk profiles in these anxious patients with CAD and the marked improvements in the overall risk profiles, levels of anxiety, and overall quality of life after cardiac rehabilitation and exercise training programs. Greater attention at detecting and treating chronic anxiety, particularly with formal cardiac rehabilitation, is needed for the secondary prevention of CAD.

Effect of age and gender on heart rate recovery after submaximal exercise during cardiac rehabilitation in patients with angina pectoris, recent acute myocardial infarction, or coronary bypass surgery

The effect of exercise training on the heart rate recovery (HRR) response to submaximal effort was examined in 81 patients during 12 weeks of phase II cardiac rehabilitation. Although HRR after submaximal effort was relatively reduced in older patients with heart disease and in women, its increase during exercise training in men and women of all ages was consistent with enhancement of parasympathetic tone during activities of daily living.

Effects of cardiac rehabilitation and exercise training on indexes of dispersion of ventricular repolarization in patients after acute myocardial infarction

We studied 50 consecutive patients with relatively preserved systolic function (ejection fraction >40%, mean 53 +/- 11%) after acute myocardial infarction, and assessed indexes of dispersion of ventricular repolarization before and after a formal, phase II cardiac rehabilitation and exercise training program. After cardiac rehabilitation, statistically significant reductions occurred in QT dispersion, JT dispersion, and in the heart rate corrected indexes. These benefits add to the proven benefits of formal cardiac rehabilitation and exercise training programs and may reduce the subsequent risks of malignant ventricular arrhythmias and sudden cardiac death.

Assessing autonomic disturbances of hypertension in the general practitioner's office: a transtelephonic approach to spectral analysis of heart rate variability

OBJECTIVES

Spectral analysis of heart rate variability (HRV) provides potentially useful information on autonomic disturbances of human hypertension. However, its practical use outside the clinical laboratory is largely unexplored. The aim of this study was to test the feasibility of assessing HRV from the general practitioner's (GP's) office, using a novel transtelephonic approach.

DESIGN

Parallel study on two similar groups: 150 subjects (100 hypertensives and 50 normotensives) studied in our hospital clinic and compared with 150 subjects studied in an out-of-hospital practice (100 hypertensive subjects from GPs' surgeries and 50 normotensive subjects participating in a multinational company's health maintenance programme).

METHODS

Spectral analysis of RR interval variability was used to assess autonomic regulation of the sino-atrial (SA) node, both at rest and during standing. For the out-of-hospital practice, strings of continuous electrocardiograms (ECGs), recorded with a microminiature instrument, were fed, off line, through standard telephone lines to our laboratory for subsequent spectral analysis.

RESULTS

RR spectral profiles obtained from healthy controls or hypertensive patients examined in their GPs' surgeries were similar to those obtained in a hospital clinic, both at rest and when standing up.

CONCLUSIONS

The present study shows the feasibility of using a transtelephonic approach to perform spectral analysis of heart rate variability from physicians' surgeries. This method could favour a more widespread use of autonomic assessment in the clinical management of hypertension.

Impairment in cardiac autonomic regulation preceding arterial hypertension in humans: insights from spectral analysis of beat-by-beat cardiovascular variability

BACKGROUND

Subjects in the upper-normal range of arterial pressure have an excess cardiovascular risk, which suggests that other factors, such as impaired autonomic regulation, might be implicated. This study was designed to assess whether noninvasive markers of cardiac and vascular autonomic regulation might already be altered in subjects with high-normal arterial pressure levels.

METHODS AND RESULTS

We performed an observational study on a population comprising 300 subjects of both sexes with arterial pressure ranging from 90/60 to 210/120 mm Hg, who were divided into 3 groups (each n=100) with average systolic pressures of 103, 133, and 163 mm Hg. Autonomic regulation was inferred from spectral analysis of RR interval and systolic arterial pressure variability, considering rest and stand-induced changes, to account for sympathetic excitatory components. Significant alterations in markers of sinoatrial regulation (increased low-frequency normalized units, reduced high-frequency normalized units, and alpha-index) were already apparent in subjects in the second tertile, ie, those with arterial pressure within normal limits. Markers of vascular regulation instead showed significant alterations in the third (hypertensive) tertile. In response to standing, changes in markers of sinoatrial modulations were gradually reduced, whereas those of vascular regulation were increased. A tight link between progression of arterial pressure and the continuum of changes in autonomic markers as shown by simple correlation analysis appeared strongly affected by age and was spread across many spectral analysis-derived variables. Hypertensive autonomic dysregulation was particularly apparent in the youngest group.

CONCLUSIONS

RR-variability parameters might prove useful to assess, with longitudinal studies, the mechanistic role of autonomic impairment in the increased risk of prehypertensive conditions.