Effects of exercise rehabilitation program on heart rate recovery in patients with chronic heart failure:

Heart rate recovery and oxygen kinetics after exercise in obstructive sleep apnea syndrome

BACKGROUND

Patients who suffer from obstructive sleep apnea (OSA) have a decreased exercise capacity and abnormal autonomic nervous function. However, the kinetics of early oxygen (O2) and heart rate recovery (HRR) have not been described.

MATERIALS AND METHODS

We evaluated 21 men with moderate to severe OSA (mean age: 48 +/- 11 yrs, mean apnea-hypopnea index [AHI]: 55 +/- 13) and without known heart disease and 10 healthy men matched for age and body mass index (BMI; controls). Men with OSA underwent overnight polysomnography, and both groups underwent symptom-limited incremental cardiopulmonary exercise testing (CPET). We recorded the CPET parameters including peak O2 uptake (VO2p), kinetics of early O2 recovery by the first degree slope of VO2 during the first minute (VO2/t slope), the time required for a 50% decline of VO2p during recovery (T(1/2)), and early heart rate recovery (HRR = HR at maximal exercise - HR at 1 min of recovery), as well as the chronotropic reserve to exercise ([CR] = [peak HR - resting HR/220 - age - resting HR] x 100). Patients with OSA had a lower VO2p (28.7 +/- 4.0 vs 34.7 +/- 6.2 mL/kg/min), VO2/t slope (1.04 +/- 0.3 vs 1.4 +/- 0.17 mL/kg/min2), and T(1/2) (74 +/- 10 vs 56 +/- 6 sec) compared to controls (all P < 0.001). In addition, both HRR and CR were lower in the OSA group (22.0 +/- 7.0 vs 31.0 +/- 6.0 bpm, P:0.003, and 79.0% +/- 15% vs 99.0% +/- 13.0%, P:0.01, respectively).

CONCLUSIONS

Patients with OSA demonstrate reduced exercise capacity, delayed oxygen kinetics, and reduced HRR. These data point to abnormal oxygen delivery and/or oxidative function of the peripheral muscles and impaired autonomic nervous activity in OSA patients.

Impairment of autonomic nervous system activity in patients with pulmonary arterial hypertension: a case control study

BACKGROUND

Chronotropic response to exercise (CR) and heart rate recovery (HRR) immediately after exercise are indirect indices of sympathetic and parasympathetic activity, respectively. The aim of this study was to evaluate CR and HRR in patients with pulmonary arterial hypertension (PAH) in relation to disease severity.

METHODS AND RESULTS

Ten PAH patients (6 females/4 males, mean age: 48+/-12 years) and 10 control subjects matched for age, gender, and body mass index (6 females/4 males, mean age: 46+/-6 years) performed a ramp incremental symptom-limited cardiopulmonary exercise test on a cycle ergometer. Main measurements included heart rate at rest (HR), CR=[(peak HR-resting HR/220-age-resting HR)x100, %], HRR(1)=HR difference from peak exercise to 1minute after, ventilatory efficiency during exercise (VE/VCO(2) slope), peak oxygen uptake (VO(2)p), and the first-degree slope of VO(2) for the first minute of the recovery period (VO(2)/t-slope). PAH patients had a significantly decreased CR (58+/-31 vs 92+/-13, %, P < .001) and HRR(1) (10+/-5 vs 29+/-6, beats/min, P < .001) as well as VO(2)p (11.9+/-3.5 vs 26.9+/-6.6, mL.kg.min) and VO(2)/t-slope (0.2+/-0.1 vs. 0.9+/-0.2, mL.kg.min(2)) compared with controls. CR and HRR(1) correlated well with VO(2)p (r=0.7; P < .001 and r=0.85; P < .001, respectively) and VO(2)/t-slope (r=0.66; P < .001 and r=0.85; P < .001, respectively) and had a significant inverse correlation with VE/VCO(2) slope (r=-0.47; P < .01 and r=-0.77; P < .001, respectively).

CONCLUSIONS

PAH patients present a significant impairment of CR and HRR(1) in relation to disease severity, indicating profound autonomic nervous system abnormalities.

Physical exercise improves the peripheral microcirculation of patients with chronic heart failure

PURPOSE

Patients with chronic heart failure (CHF) present with microcirculation alterations, partially attributed to endothelial dysfunction. Exercise training has been shown to induce beneficial effects in CHF patients. The aim of our study was to assess the effect of physical exercise on the microcirculation of CHF patients by near-infrared spectroscopy (NIRS).

METHODS

Sixteen consecutive stable CHF patients (men, n = 10; mean age = 50 +/- 12 years) participated in a 3-month rehabilitation program (3 sessions per week). All patients performed symptom-limited, ramp-incremental cardiopulmonary exercise testing on a cycle ergometer before and after the completion of the program. Measurements included peak oxygen uptake (VO2peak), VO2 at anaerobic threshold (AT), and first-degree slope of VO2 during the first minute of recovery (VO2/t slope). Tissue oxygen saturation was continuously measured by NIRS at the thenar muscle during a 3-minute vascular occlusion with a pneumatic cuff (occlusion technique) before and after the rehabilitation program.

RESULTS

The oxygen reperfusion rate (%/min) following the release of vascular occlusion increased significantly after the rehabilitation program (450 +/- 105 to 532 +/- 151, P = .004) as did vascular reactivity (from 27 +/- 13%/min to 39 +/- 21%/min, P = .006). In addition, there was a significant increase in VO2peak and AT (from 14.3 +/- 4.7 mL . kg . min to 16.7 +/- 6.3 mL . kg . min and from 9.5 +/- 3.6 mL . kg . min to 11.3 +/- 4 mL . kg . min, P = .007 and P = .012, respectively) as well as in VO2/t slope (from 0.35 +/- 0.17 to 0.51 +/- 0.07 mL . kg . min, P = .005).

CONCLUSIONS

Peripheral microcirculation of CHF patients measured by NIRS improved after the rehabilitation program. NIRS is a noninvasive technique that could be used to evaluate the effect of rehabilitation on the peripheral microcirculation of CHF patients.

Longitudinal cognitive performance in older adults with cardiovascular disease: evidence for improvement in heart failure

BACKGROUND

Cardiovascular disease (CVD) and particularly heart failure (HF) have been associated with cognitive impairment in cross-sectional studies, but it is unclear how cognitive impairment progresses over time in older adults with these conditions.

OBJECTIVE

The aim of this study was to prospectively examine cognitive function in patients with HF versus other forms of CVD.

METHOD

Seventy-five older adults (aged 53-84 years) with CVD underwent Doppler echocardiogram to evaluate cardiac status and 2 administrations of the Dementia Rating Scale (DRS), a test of global cognitive functioning, 12 months apart.

RESULTS

Although DRS performance did not statistically differ between groups at either administration, a significant between-group difference in the rate of cognitive change emerged (lambda = 0.87; F = 10.50; P = .002; omega 2 = 0.11). Follow-up analyses revealed that patients with HF improved significantly on global DRS performance, whereas patients with other forms of CVD remained stable. More specifically, patients with HF showed improvement on subscales of attention, initiation/perseveration, and conceptualization. Exploratory analyses indicated that higher diastolic blood pressure at baseline was associated with improved DRS performance in patients with HF (r = 0.38; P = .02).

CONCLUSIONS

Patients with HF exhibited modest cognitive improvements during 12 months, particularly in attention and executive functioning. Higher diastolic blood pressure at baseline was associated with improvement. These results suggest that cognitive impairment in patients with HF may be modifiable and that improved blood pressure control may be an important contributor to improved function. Further prospective studies are needed to replicate results and determine underlying mechanisms.

Heart rate recovery after exercise in chronic heart failure: role of vital exhaustion and type D personality

OBJECTIVE

Vital exhaustion and type D personality previously predicted mortality and cardiac events in patients with chronic heart failure (CHF). Reduced heart rate recovery (HRR) also predicts morbidity and mortality in CHF. We hypothesized that elevated levels of vital exhaustion and type D personality are both associated with decreased HRR.

METHODS

Fifty-one patients with CHF (mean age 58+/-12 years, 82% men) and left ventricular ejection fraction (LVEF) < or = 40% underwent standard exercise testing before receiving outpatient cardiac rehabilitation. They completed the 9-item short form of the Maastricht Vital Exhaustion Questionnaire and the 14-item type D questionnaire asking about negative affectivity and social inhibition. HRR was calculated as the difference between heart rate at the end of exercise and 1 min after abrupt cessation of exercise (HRR-1). Regression analyses were adjusted for gender, age, LVEF, and maximum exercise capacity.

RESULTS

Vital exhaustion explained 8.4% of the variance in continuous HRR-1 (p=0.045). For each point increase on the vital exhaustion score (range 0-18) there was a mean+/-SEM decrease of 0.54+/-0.26 bpm in HRR-1. Type D personality showed a trend toward statistical significance for being associated with lower levels of HRR-1 explaining 6.5% of the variance (p<0.08). The likelihood of having HRR-1 < or = 18 bpm was significantly higher in patients with type D personality than in those without (odds ratio=7.62, 95% CI 1.50-38.80).

CONCLUSIONS

Elevated levels of vital exhaustion and type D personality were both independently associated with reduced HRR-1. The findings provide a hitherto not explored psychobiological explanation for poor cardiac outcome in patients with CHF.

A Systematic Review of Exercise Interventions in Patients With Heart Failure

The incidence of heart failure (HF) is increasing as the population ages. Pharmacotherapy is an important component of treatment and yields significant improvements in survival and quality of life. In recent decades, exercise has gradually become accepted as an intervention beneficial to patients with HF, but more information is needed to clarify the effects of exercise and optimize interventions. Therefore, a systematic review of randomized controlled trials published from 1966 to October 2006 was carried out via PubMed. About 69 trials were reviewed, which used as main outcome measures: (a) central hemodynamic parameters, (b) peripheral blood flow, (c) endothelial function, (d) activation of neurohormones and cytokine systems, (e) structure of and metabolism in skeletal muscles, and/or (f) quality of life. Study findings suggest that the favorable physiological responses to exercise might slow some of the pathophysiological progression of HF. However, most of the trials reviewed here were based on relatively small samples and selected participant groups, and the exercise programs varied widely. These limitations and inconsistencies need to be addressed through further studies. Furthermore, reliable strategies for maintaining the positive effects of exercise and extending them to patients' daily life and quality of life are scarce in these trials. These domains need further exploration through rationally designed, large-scale randomized controlled trials.

Heart rate recovery and prognosis in heart failure patients

The aim of this study is to evaluate the usefulness of heart rate recovery (HRRec) for assessing risk of death in heart failure (HF) patients. Echocardiographic and clinical exercise data were analyzed retrospectively on 712 HF patients (EF < or = 45%). HRRec was calculated as peak exercise heart rate - heart rate at 1 min of active recovery. Patients were followed for all-cause mortality (5.9 +/- 3.3 years follow-up). Groups were identified according to HRRec: group-1 (HRR < or = 4 bpm), group-2 (5 < or = HRR < or = 9 bpm), and group-3 (HRR > or = 10). Kaplan-Meier analysis estimated survival of 91, 64, and 43% (group-1); 94, 76, and 63% (group-2); and 92, 82, and 70% (group-3) at 1, 5, and 10 years, respectively. Ranked HRRec independently predicted mortality after adjusting for age, gender, NYHA class, LVEF and BMI, but was not independent of exercise time, peak V(O)(2) and V(E)/V(CO)(2) at nadir. HRRec is a useful prognostic marker in patients with HF, particularly when gas exchange measures are not available.

Effects of cardiac rehabilitation program on exercise capacity and chronotropic variables in patients with orthotopic heart transplant

AIM

To evaluate the effects of home- and hospital-exercise programs on exercise capacity and chronotropic variables in patients with heart transplantation.

METHODS

Forty patients were randomized into two groups either hospital- or home-based exercise program. The patients were compared, before and after the rehabilitation program, with respect to maximal oxygen uptake (pVO(2)), chronotropic variables [heart rate reserve (HRR(e)), heart rate recovery (HRR(1)), and chronotropic response index (CRI)] and Duke Treadmill Score (DTS).

RESULTS

Hospital-based exercise group has shown a significant recovery in post-exercise pVO(2) (pre-exercise 16.73 +/- 3.9 ml/kg/min, post-exercise 19.53 +/- 3.89 ml/kg/min, P = 0.002) and DTS (pre-exercise 4.74 +/- 1.17, post-exercise 5.61 +/- 1.11, P = 0.002). A significant recovery in favor of the hospital-based exercise group was found in HRR(e) (pre-exercise 26.9 +/- 14.6, post-exercise 34.6 +/- 14.6, P = 0.01). No significant change was observed in HRR(1) (pre-exercise -1.38 +/- 1.04, post-exercise -1.21 +/- 1.89, P = 0.49) and CRI (pre-exercise 0.44 +/- 0.23, post-exercise 0.48 +/- 0.20, P = 0.15) in hospital-based exercise group. No significant change was observed in any parameters of home-based group (P > 0.05).

CONCLUSION

A significant recovery was observed both in the functional capacity and the chronotropic response in hospital-based exercise program. Exercise programs that are planned to be performed under supervision in rehabilitation units are useful for the patients with heart transplant in terms of the exercise capacity and chronotropic variables.

Effects of exercise training on heart rate recovery in patients with chronic heart failure

BACKGROUND

Heart rate recovery (HRR) is a marker of vagal tone that is associated with survival, but little is known about the effects of exercise training on HRR in patients with heart failure (HF).

METHODS

Twenty-four patients with HF were randomized to a 2-month residential rehabilitation program or to usual care. Symptom-limited exercise testing was performed at baseline and at discharge from the program. Heart rate recovery was expressed as the decline in heart rate from peak exercise through 6 minutes into recovery. In addition, HRR recovery curves were normalized to a range of 1 at peak heart rate and 0 at 6 minutes and adjusted for differences in heart rate reserve, facilitating the comparison of recovery curve shapes between groups.

RESULTS

Mean peak oxygen uptake and oxygen uptake at the lactate threshold increased 26% (P < .05) and 39% (P < .001), respectively, in the exercise group, whereas neither of these responses changed significantly among controls. Heart rate recovery was significantly more rapid in the exercise group after training (main effect 12.6 vs 2.6 beat/min in the trained and control groups, respectively, P = .005). The normalized curves showed that the largest improvement in recovery curve shape occurred in the exercise group, but most of the HRR improvement was accounted for by a widening of the difference between peak and resting heart rate.

CONCLUSION

Exercise training results in a faster HRR in patients with HF. Heart rate recovery, as a simple marker of autonomic function, is an easily acquired response that may be useful for evaluating patient outcomes in cardiac rehabilitation.

The effects of exercise training on the kinetics of oxygen uptake in patients with chronic heart failure

BACKGROUND

Prolonged oxygen uptake kinetics (O2 kinetics), following the onset of a constant workload of exercise has been associated with a poor prognosis in patients with chronic heart failure. This study aimed to determine both continuous and interval training effects on the different O2-kinetics phases in these patients.

DESIGN

Twenty-one patients (60+/-8 years) with stable chronic heart failure participated in a 36-session exercise rehabilitation program (three times weekly). Patients were randomly assigned to interval training (n=11; 100% of peak work rate for 30 s, alternating with 30 s-rest) and to continuous training (n=10; 50% of peak work rate).

METHODS

Before and after the completion of the program, all patients performed both incremental symptom-limited and constant workload submaximal cardiopulmonary exercise tests. Phase I O2-kinetics was evaluated by time (t), from the start of exercise until the onset of decreased respiratory exchange ratio and phase II by the time constant (tau) of the response from the end of phase I until steady state.

RESULTS

After training, there was a significant increase in peak oxygen uptake and peak work rate in both continuous (15.3+/-4.4 vs. 16.6+/-4.5 ml/kg per min; P=0.03 and 81.8+/-40.1 vs. 94.7+/-46.1 W; P=0.03) and interval training groups (14.2+/-3.1 vs. 15.4+/-4.2 ml/kg per min; P=0.03 and 82.5+/-24.1 vs. 93.7+/-30.1 W; P=0.04). Patients who underwent interval training had a significant decrease in t (39.7+/-3.7 to 36.1+/-6.9 s; P=0.05), but not tau (59.6+/-9.4 to 58.9+/-8.5 s; P=ns), whereas those assigned to continuous training had a significant decrease in both t (40.6+/-6.1 to 36.4+/-5.4 s; P=0.01) and tau (63.3+/-23.6 to 42.5+/-16.7 s; P=0.03).

CONCLUSIONS

Exercise training improves O2 kinetics in chronic heart failure patients. Both continuous and interval training improve phase I O2-kinetics, but continuous training results in superior improvement of the phase II O2-kinetics, an indirect index of muscle oxidative capacity.