Exercise training in patients with congestive heart failure

Exercise for those with chronic heart failure matching programs to patients

Exercise training increases functional capacity and improves symptoms in selected patients with chronic heart failure and moderate-to-severe left ventricular systolic dysfunction. Patients should be assessed before they start an exercise program. Initial programs should be supervised, and the duration increased as tolerated. The most consistent benefits occur with exercise done at least three times per week for 12 or more weeks. Aerobic sessions can vary from 20 to 40 minutes, at 50% to 85% of peak heart rate on graded exercise tests or 40% to 70% of peak oxygen consumption. Low-risk patients who have completed at least 6 to 12 weeks of exercise without adverse effects may incorporate light-to-moderate resistance training.

Rate-responsive pacing improves exercise tolerance in heart transplant recipients: a pilot study

BACKGROUND

Chronotropic incompetence is one cause of diminished exercise capacity in heart transplant recipients. If reinnervation occurs, it often is late after transplantation and is not always accompanied by functional improvements in peak heart rate and appropriate tachycardia during exercise. To determine the efficacy of rate-responsive pacing on peak heart rate and exercise capacity, the authors studied eight male heart transplant recipients (age 57 +/- 12 years; 23 +/- 9 months after transplantation) that had either atrial or dual-chambered pacemakers.

METHODS

All subjects completed two maximal graded exercise tests (GXT) using the Naughton treadmill protocol. During the first GXT, pacemakers were programmed for bradycardia support only and without rate responsiveness (unpaced). After a 14-day regimen of beta blockade with metoprolol to nullify the influence of circulating catecholamines on heart rate, subjects performed the second GXT with pacemakers programmed to respond optimally in the rate-responsive mode (paced).

RESULTS

Peak heart rate (149 versus 129 bpm), peak oxygen uptake (18.9 versus 15.4 mL/kg/min), treadmill time to exhaustion (14.6 versus 12.4 min), and minute ventilation (76.7 versus 66.2 L/min) were significantly increased (P < or = 0.05) during the paced versus unpaced GXT.

CONCLUSIONS

The results of this study demonstrate that chronotropic support of the transplanted heart using a rate-responsive pacemaker, with activity-based sensors programmed for maximal sensitivity, improves both peak heart rate and exercise capacity in heart transplant recipients significantly more than circulating catecholamines alone.

Exercise following heart transplantation

During the past 2 decades, heart transplantation has evolved from an experimental procedure to an accepted life-extending therapy for patients with endstage heart failure. However, with dramatic improvements in organ preservation, surgery and immunosuppressive drug management, short term survival is no longer the pivotal issue for most heart transplant recipients (HTR). Rather, a return to functional lifestyle with good quality of life is now the desired procedural outcome. To achieve this outcome, aggressive exercise rehabilitation is essential. HTR present unique exercise challenges. Preoperatively, most of these patients had chronic debilitating cardiac illness. Many HTR have had prolonged pretransplantation hospitalisation for inotropic support or a ventricular assist device. Decrements in peak oxygen consumption (VO2peak) and related cardiovascular parameters regress approximately 26% within the first 1 to 3 weeks of sustained bed rest. Consequently, extremely poor aerobic capacity and cardiac cachexia are not unusual occurrences in HTR who have required mechanical support or been confined to bed rest. Moreover, HTR must also contend with de novo exercise challenges conferred by chronic cardiac denervation and the multiple sequelae resulting from immunosuppression therapy. There is ample evidence that both endurance and resistance training are well tolerated in HTR. Moreover, there is growing clinical consensus that specific endurance and resistance training regimens in HTR can be efficacious adjunctive therapies in the prevention of immunosuppression-induced adverse effects and the reversal of pathophysiological consequences associated with cardiac denervation and antecedent heart failure. For example, some HTR who remain compliant during strenuous long term endurance training programmes achieve peak heart rate and VO2peak values late after transplantation that approach age-matched norms (up to approximately 95% of predicted). These benefits are not seen in HTR who do not participate in structured endurance exercise training. Rather, peak heart rate and VO2peak values in untrained HTR remain approximately 60 to 70% of predicted indefinitely. However, the mechanisms responsible for improved peak heart rate, VO2peak and total exercise time are not completely understood and require further investigation. Recent studies have also demonstrated that resistance exercise training may be an effective countermeasure for corticosteroid-induced osteoporosis and skeletal muscle myopathy. HTR who participate in specific resistance training programmes successfully restore bone mineral density (BMD) in both the axial and appendicular skeleton to pretransplantation levels, increase lean mass to levels greater than pretransplantation, and reduce body fat. In contrast, HTR who do not participate in resistance training lose approximately 15% BMD from the lumbar spine early in the postoperative period and experience further gradual reductions in BMD and muscle mass late after transplantation.

Moderate-intensity exercise training with elements of step aerobics in patients with severe chronic heart failure

OBJECTIVE

To evaluate whether a specific program of moderate-intensity step aerobics training may be sufficient to improve the exercise tolerance of patients with severe chronic heart failure.

PATIENTS

Twenty-six patients (22 men, 4 women; mean +/- SD age, 54 +/- 9yrs) with a history of severe chronic heart failure (left ventricular ejection fraction of 18% +/- 8%).

STUDY DESIGN

Prospective, randomized, controlled trial. Patients were randomized into exercise and control groups. All patients underwent a clinical examination and a ramp pattern cycle exercise test before and after the observation period. The exercise group underwent a moderate-intensity (50% of peak oxygen uptake) 12-week training program, progressing to 100 minutes per week of step aerobics and 50 minutes per week of cycling. The control group did not perform a training program.

MAIN OUTCOME MEASURES

Peak oxygen uptake, peak workload, percent of predicted power ability.

RESULTS

Significant increases in peak oxygen uptake (15 +/- 3.4 to 18.5 +/- 2.9mL/kg/min; p = .001), peak workload (77 +/- 26 to 99 +/- 31 watts; p = .000), and percent of predicted power ability (43% +/- 10% to 56% +/- 13%; p = .000) were observed in the exercise group. No significant changes in baseline parameters occurred in the control group. There were no critical changes in heart rate or blood pressure in either group.

CONCLUSION

Moderate-intensity step aerobics training significantly increases peak oxygen uptake and peak workloads in patients with severe chronic heart failure.

Exercise training in heart failure

Patients with heart failure challenge the clinician with a constellation of difficult clinical, pathophysiologic, and psychologic issues. As a result, until recently, exercise training was not considered a safe and effective treatment strategy to be used in these patients. However, in the past 10 years, data from both randomized and nonrandomized trials showed that regular exercise training in patients with stable Class II and III heart failure can safely improve exercise tolerance, attenuate an overactivated sympathetic nervous system, partially reverse skeletal muscle abnormalities, and enhance health-related quality of life. These outcomes are achievable with a relatively moderate dose of physical activity, such as 30 to 60 minutes of walking or cycling 3 to 5 days per week at an intensity equivalent to 60% to 70% of peak oxygen consumption. Sufficiently powered trials are needed to assess morbidity, mortality, and cost-effectiveness endpoints relative to exercise training in patients with heart failure.

Exercise training in patients with CHF and heart transplant recipients

The number of chronic heart failure (CHF) patients and heart transplantation (HT) recipients enrolled in rehabilitation and maintenance exercise programs continues to expand. There is growing clinical consensus that stable patients with CHF respond favorably to exercise training and convincing evidence that exercise training should be an essential adjunct therapy in postoperative management of HT recipients. This review examines the following specific advances in exercise physiology for heart failure and heart transplantation patients: 1) the mechanisms of exercise intolerance in CHF and the results of exercise rehabilitation studies in these patients; 2) the exercise challenges conferred by glucocorticoid therapy and chronic cardiac denervation in HT recipients; and 3) a summary of current recommendations and guidelines for exercise prescription in each patient population.