Exercise Based Cardiac Rehabilitation in Chronic Heart Failure

CLINICAL PRACTICE Exercise based cardiac Rehabilitation rehabilitation in chronic Frances M Wise MBBS, PhD, FAFRM(RACP), is Senior Rehabilitation Physician, Cardiac Rehabilitation Unit, heart failure Caulfield General Medical Centre, Victoria. [email protected] People with chronic heart failure often present to their general practitioner with questions about their participation in cardiac rehabilitation programs. This article outlines the risks and benefits of such programs. Chronic heart failure (CHF) is a leading cause heart failure is presented in Table 1. of morbidity in the industrialised world.1 It can be Studies show diagnosis by clinical means alone is defined as ‘a complex clinical syndrome with typical often inaccurate5,6 particularly in women, the elderly and symptoms (eg. dyspnoea, fatigue) that can occur the obese. The National Heart Foundation of Australia, at rest or on effort, and characterised by objective the Cardiac Society of Australia and New Zealand, evidence of an underlying structural abnormality or the European Society of Cardiology, and the National cardiac dysfunction that impairs the ability of the Institute for Clinical Excellence in the United Kingdom ventricle to fill with or eject blood (particularly during recommend that all patients clinically suspected exercise)’.1 Clinical improvement with treatment further of having CHF undergo echocardiography to formally strengthens the diagnosis of CHF. diagnose the condition.1,5,7 Pathogenesis Incidence, prevalence and prognosis Heart failure is characterised by reduced exercise tolerance Approximately 1.5–2.0% of the Australian population is and poor quality of life. This is due in part to an enlarged and affected by heart failure, with 20 000 new cases diagnosed ineffective myocardium unable to maintain sufficient cardiac each year.1 The incidence and prevalence increases with age, output to meet tissue demands. In addition, the mechanisms from 1% in patients aged 50 years to over 50% in those underlying peripheral deconditioning in CHF (characterised by aged 85 years or over.2,3 skeletal muscle atrophy with associated early fatigability and The long term prognosis is poor: half of those diagnosed decrease in strength) include: with CHF will die within 4 years and the 1 year mortality • impairment of skeletal muscle blood flow (including rate in severe heart failure is over 50%.4,5 Predictors of poor abnormalities in vasodilatation) prognosis in CHF are summarised in Table 2. The most • impairment of skeletal muscle metabolism common causes of CHF are ischaemic heart disease (over • elevation of plasma cytokines leading to muscle half of new cases), hypertension (two-thirds of cases) and catabolism idiopathic dilated cardiomyopathy (~5–10% of cases).1 • reduced percentage of type 1 (slow twitch) muscle fibres in skeletal muscle Diagnosis of CHF • increased dependence on anaerobic pathways for The criteria for diagnosis are: energy production, and • symptoms of heart failure at rest or during exercise (eg. • activation of the renin angiotensin and sympathetic dyspnoea, fatigue, oedema exercise intolerance), and systems leading to a rise in resting heart rate.8–12 • objective evidence (preferably by echocardiography) of cardiac dysfunction (systolic and/or diastolic) at rest and Cardiac rehabilitation for CHF patients in cases where the diagnosis is in doubt, and Historically, patients with CHF were excluded from cardiac • response to treatment directed toward heart failure.5 rehabilitation programs as it was thought that exercise The New York Heart Association (NYHA) classification of might cause decompensation in an already weakened Reprinted from Australian Family Physician Vol. 36, No. 12, December 2007 1019 CLINICAL PRACTICE Exercise based cardiac rehabilitation in chronic heart failure heart.9 Gradually evidence emerged that What is cardiac rehabilitation? a cardiac rehabilitation program are presented supported the benefits of exercise and in 1994 in Table 4. guidelines were published recommending Cardiac rehabilitation units offer supervised In coronary heart disease patients, cardiac the routine use of a supervised rehabilitation exercise and are involved in secondary prevention rehabilitation is known to reduce rates of exercise program.13 Subsequent studies have of cardiovascular disease via education, mortality and further cardiac events and to demonstrated the general benefits of cardiac counselling and behavioural interventions to improve physical and psychosocial functioning, rehabilitation in this group,14 and supervised promote lifestyle change and modify cardiac risk including earlier return to work. Evidence now exercise programs are now recommended for factors. Cardiac rehabilitation is typically provided exists that cardiac rehabilitation also benefits all CHF patients as part of nonpharmacological by a multidisciplinary team of medical, nursing CHF patients in terms of exercise capacity and management (Table 3).15 and allied health staff. The core components of health related quality of life.9,14 Who should have rehabilitation? Table 1. New York Heart Association classification of heart failure The Best practice guidelines for cardiac Class I (mild) No limitation on physical activity. Ordinary physical activity 15 does not cause undue fatigue, palpitation, or dyspnoea rehabilitation and secondary prevention state (shortness of breath) that: ‘All patients with heart failure should be enrolled in an exercise program as a part of Class II (mild) Slight limitation of physical activity. Comfortable at rest, but ordinary physical activity results in fatigue, palpitation, or comprehensive rehabilitation, including before dyspnoea and after transplantation’. In practice, however, Class III (moderate) Marked limitation of physical activity. Comfortable at rest, cardiac rehabilitation (of which exercise training but less than ordinary activity causes fatigue, palpitation, or is an integral part) is typically offered to patients dyspnoea with stable NYHA class II or III heart failure. It Class IV (severe) Unable to carry out any physical activity without discomfort. is now generally accepted that exercise training Symptoms of cardiac insufficiency at rest. If any physical – specifically aerobic exercise training in a activity is undertaken, discomfort is increased supervised hospital based setting – is safe in such patients, but as yet no research evidence Table 2. Predictors of outcome in CHF1 Demographic Clinical Electrophysiologic Functional/exertional Blood Central and historical haemodynamic Advanced age Persistent low Broad QRS VO2 max (max oxygen High serum brain Low left blood pressure consumption mL/kg/min) natriuretic peptide ventricular <10–14 ejection fraction Resuscitated NYHA Low heart rate High VE/VCO2 ratio Low serum Impaired right sudden death functional variability sodium ventricular class III-IV function Diabetes Low body Complex ventricular Low 6 minute walking High serum Low cardiac index mass index rhythms ability creatinine Coronary Ventilatory T wave alternans High serum High left aetiology rhythm bilirubin ventricular filling and rate pressure disturbances Ethnicity High heart rate Anaemia Restrictive mitral filling pattern High heart rate High serum Increased left norepinephrine ventricular volumes High serum Cardiothoracic troponin ratio High serum uric acid VE = ventilation volume per minute, VCO2 = ventilation of CO2 Strong predictors are indicated in bold 1020 Reprinted from Australian Family Physician Vol. 36, No. 12, December 2007 Exercise based cardiac rehabilitation in chronic heart failure CLINICAL PRACTICE recommends exercise training in unstable heart to strengthen individual muscle groups in both related to exercise during more than 60 000 failure or those with NYHA class IV.14 the upper and lower body. Based on recent patient hours of exercise training.19 However, Even for patients with stable heart failure, scientific evidence, it is safe in CHF patients.18 certain types of exercise should be avoided for whom cardiac rehabilitation is potentially Small free weights (0.5–2 kg), elastic bands, by people with CHF. Jogging is not advisable appropriate, there are contraindications or repetitive isolated muscle training can be due to the oxygen consumption required to exercise training (Table 5). Therefore, it is used. Combined aerobic and resistance training at even slow speeds. Swimming should recommended that all patients be reviewed administered as a circuit program can increase be avoided because of the acute volume by a cardiologist before commencement of an skeletal muscle strength and exercise tolerance loading of the left ventricle and the increased exercise training program. (peak VO2), thereby improving the patient’s pulmonary capillary wedge pressure resulting Current recommendations physical capacity for the tasks of daily living.18 from hydrostatic pressure when immersed Pulse, blood pressure and symptoms should in water. Outdoor cycling and overcoming The ideal exercise prescription should be based be monitored before, during and after exercise. environmental stress factors (eg. slopes, head on measurement of a patient’s maximum Exercise should be terminated if there is an winds) require significant oxygen consumption oxygen consumption during exercise (VO2 acute decrease in blood pressure, onset of and should only be undertaken by long term max). Traditionally this has been calculated using angina, significant dyspnoea and fatigue, a stable NYHA class I or II patients.9 maximal exercise

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