This is a case study of Aneka Jacobsen, who seeks cardiac rehabilitation (CR) phase III, after a recent myocardial infarction (MI) which is commonly known as a heart attack. This is considered the intensive supervised phase, usually 4-6 weeks post event and discharge from hospital. It may be offered in supervised groups within the outpatient department of a hospital, in community setting or as part of a home-based package. The case study briefly examines her past and current history, including data given from an exercise tolerance test (ETT), performed by the patient prior to being discharged from the hospital. Evidences collected from various research studies and guidelines from a number of heart associations worldwide has been used to support and justify clinical reasoning why patients like Aneka would benefit from participating in this rehabilitation phase after her recent cardiac event. The risks factors for Aneka has been evaluated and following this, an appropriate CR phase III programme has been proposed for her from the role of a physiotherapist as part of the multidisciplinary team (MDT) approach in the management of this patient.
Acevedo et al 2011, reported that coronary heart disease (CHD) is the leading cause of death worldwide and in recent years there has been success in treating modifiable risk factors of CHD, such as high blood pressure and dyslipidemia. However, it has not been as successful to treat other risk factors such as overweight, obesity and physical inactivity, since these required lifestyle changes. Thus, most patients with cardiac disease present as sedentary individuals who do not participate in any form of regular exercise or physical actively accumulating 30 mins. Hence, they are often deconditioned and overweight. Over the past few decades, CR programmes have been prescribed for patients following MI or coronary artery bypass graft (CABG) surgery but more recently, CR encompasses a wide range of cardiac problems (Taylor et al, 2008).
The NICE guidelines 2003, Scottish Intercollegiate Guideline Network (SIGN) 2002, the American Heart Association (AHA), American College of Cardiology (ACC), the National Institute of Health, the American College of Sport Medicine (ACSM), the European Society of Cardiology (ESC) have all strongly advocated regular physical activity as a strategy to reduce risks of CHD in their guidelines (Acevedo et al, 2011). CR programs should not only include exercise components but also provide comprehensive care and education about cardiovascular risk factors such as smoking, behavioural intervention, weight management and vocational rehabilitation to assist patients returning to work or retirement (Taylor et al, 2008). Furthermore, they stated that CR programmes should pertain to the emotional, physical and educational requirements of the patient and their family. The integral part of their management should include goals to:
Decrease cardiac morbidity and relieve symptoms.
Encourage ability to resume normal activities by increasing fitness.
Reduce anxiety by understanding own disease and promote self-confidence. Common hallmark problems associated with CVD is a marked reduction in exercise capacity accompanying with symptoms of severe shortness of breath (SOB) and fatigue during exercise. Reduced exercise capacity, measured as peak oxygen consumption, (VO2max) is major contributor of poor quality of life since it has direct impact of ability to perform activities of daily living ( ADL) and is a predictor of rehospitalisation and mortality (Francis et al, 2000). However, it has been suggested that exercise intolerance is not exclusively dependent on poor cardiac pump function alone, but is also due to changes in the skeletal muscle in the periphery (Coats et al, 1994). These peripheral abnormalities include reduced capacity of exercising muscle to utilise oxygen, impaired blood flow to exercising muscles, increased level of pro-inflammatory cytokines and oxidative stress (Magnusson et al 1994, Wilson et al 1993).
Patient’s Medical History
Aneka is a 54 year old woman with a history of angina and mild heart failure (CHF) since 2006. She had her first MI in 2007, followed by another in May 2011. Following this event, she had two coronary artery bypass graft (CABG) surgeries. MI is a pathological term used to describe necrosis of a part of the heart muscle. It occurs as one of a clinical manifestation of ischemia as a result of occlusion of at least one point in the arterial system which leads to sustained blood flow impairment on exertion e.g. a mismatch in demand and supply of perfusion and is usually due to blocking of a narrowed artery previously narrowed by atherosclerosis. To rectify the occlusion, CABG surgery is commonly carried out. It is a procedure which involves bypassing the occluded narrow section of their coronary arteries by grafting a blood vessel between the ascending aorta and a point on the coronary arteries distal to the obstruction. Prior to this hospital admission, her social history reveals she has led a sedentary life style, a heavy smoker for many years since the age of 25 and only stopped 4 years ago after she suffered the first heart attack.
She is currently prescribed a number of medications, all of which have been recommended by the NICE Clinical Guideline 48, Myocardial Infarction 2007, to control symptoms of angina, heart failure and left ventricular systolic dysfunction including anti-clotting drugs. The ETT was aborted after 51/2 mins when the ECG revealed that there was a I mm ST depression (a zone of ischemia in the surrounding heart tissue) and when she reported SOB. Results from the test showed that patient currently has METs (metabolic equivalent task) value of less than 3, which is an expression of the amount of energy required to perform certain physical activities. For example, resting metabolic rate is normally given as 3.5mls O2 Kg-1 min-1. (I MET). Therefore, calculating for physical activities would be multiples of this. The ECG result also identified that the patient has impaired left ventricular (LV) function which results in a reduction of the ejection fraction (EF) of 45% which is considered moderate risk.
EF is the amount of blood ejected by the heart in each cycle and in normal individuals it should be around 60%. A low EF results in low stroke volume (SV), which is the product of cardiac output (CO) and heart rate (HR). (SV = CO x HR). Therefore, in order to maintain cardiac output, heart rate has to increase. If this is the case, it may lead to more stress on the heart and an increase demand for oxygen, which can lead to further ST depression and higher risk of ischemia, angina or arrhythmias due to inadequate perfusion to meet myocardial demands. According to AACVPR 2004 stratification for risk of cardiac events, patients with highest risks are assumed to be ones with the presence of any one or more of the factors listed in their table below. Hence, this places this patient in the high risk category since her past and current history reveals she has at least 3 risk factors. These include a history of cardiac arrest, presence of CHF and angina on low level of exertion (METS value less than 5). Patient’s Problem List.
Reduced exercise tolerance with SOB and occasional angina on exertion.
METS score less than 3.
1 mm ST depression on ECG.
EF 45% (moderate risk).
Effects of Exercise Training
Aneka’s medical history and her problem list clearly demonstrates that CR is appropriate for her. The primary objective for CHD patients is endurance training which refers to activities utilising large muscle groups for a sustained period and is rhythmic and aerobic in nature resulting in an increase maximal oxygen up take ( VO2 max) (Taylor et al, 2008) which depends on the potential for inducing changes centrally and peripherally. Peripheral changes take place within skeletal and cardiac muscles which will enhance abilities to extract and utility of oxygen by:-
Increased number and size of mitochondria
Increased number of oxidative enzyme activity
Since training does not alter HR, an increase in stroke volume must be a result of increase cardiac output, which is achieved through central changes by:
Increased left ventricular mass and chamber size (the heart itself is a muscle and is adaptable to atrophic/ hypertrophic changes.).
Increased total blood volume.
Reduced total peripheral residence at maximal exercise.
The BACR 1995, explained that increasing VO2 max for cardiac patient does not directly benefit them since their daily activities rarely demand such effort. However, promoting daily activities at sub maximal levels will lead to an increase in exercise capacity and therefore will result in reduced physiological stress, which includes heart rate and blood pressure. Since myocardial oxygen consumption (MVO2) is determined by heart rate and systolic blood pressure, a reduction in either or both will delay the onset of ischemia and reduce the risk of arrhythmias. (Taylor et al, 2008).
Phase 3 Cardiac Rehabilitation Goals
This is considered the intensive supervised phase, usually 4-6 weeks post event and discharge from hospital. It may be offered in supervised groups within the outpatient department of a hospital, in community setting or as part of a home-based package. It is important to make sure that the goals set are realistic and achievable and are collaborations of objective agreed by both the patient and therapist. In this particular study, it has not been possible to carry out this process. Therefore, the intended programme will be based on recommended guidelines and Aneka’s subjective and objective history.
BACR 1995, suggested that, key elements of an exercise programme safety should include medical screening, assessments, risk stratification, inclusion/exclusion criteria for exercise sessions, supervision and monitoring of patient. Furthermore, identification of high risk patients is of paramount importance to ensure the exercise programme is suitable for the patient’s safety. This usually involves careful consideration of the patient’s cardiac history and current cardiac status Its outcome allows high risk patients to be identified and consequently be closely monitored during any exercise session and to ensure resuscitation resources are readily available in an emergency (BACR, 1995). Prior to commencing a phase III exercise session, the patient must be given a functional test which can be either a 6 minute walk test shuttle walk or Chester step test (CTS), especially if they have not had an ETT. Based on Aneka’s current condition she is only able to manage very gentle activities e.g. slow walking on flat surface, dressing herself or dish washing.
Therefore, a suitable functional test at this stage would be the 6 minutes’ walk test, since it requires non-incremental exertion. The result will allow a METs score to be calculated and patient’s BP physiological response to exercise to be monitored, aiding appropriate exercise prescription. These METs values are useful when finding comparable activities that can be given to the patient with minimal risks of over exertion and provides reassurance to the patients themselves, given them the confidence to resume previous ADLs or leisure activities they used to enjoy. Hence, increasing their motivation, self-efficacy, adherence with programme objectives and reduce reliance for help from family or their carers. atient’s exercise programme should be safe, appropriate and has effective outcome which are dependent on manipulation of the FITT principles based on the ACSM 2006 guidelines for phase III rehab:- Frequency: 5 times per week
Intensity: Approx 60-75% HR max. 12-13 on Borg scale of perceived exertion, if low risk Type: Intermittent mode progressing to continuous as appropriate. Time: minimum of 20-30 mins of CV exercises continuous or accumulative. Research has shown that 3 structured exercise programme per week which can be home exercises or class based with brisk walks on other days to make up the number of 5 sessions per week is required. However, if patient is considered high risk like this patient, the intended HR max that the patient should aim for, should initially be reduced e.g. approx 50% HR max. 11-12 Borg scale, but the numbers of structured exercise sessions needs to be increased to 5 as oppose to 3 (BACR, 1995). Acevedo et al 2011, also indicated that another goal of most exercise program is to increase calorific expenditure, targeting at least 2000 kcal per week, which would contribute to weight loss management. For patients with angina, the rehab aims are to improve their exercise tolerance, sub anginal threshold and reduce the frequency of angina episodes (BARC, 1995). To achieve physiological adaptations, the concept of Laws of Training e.g. the over loading principle must be adhered to in programmes which involves exercise intended to challenge any muscle group (ACSM, 2006). These principles include:
Progressive overload which states that for tissues to improve its function, it must be exposed to more demand than it is normally accustomed to. Specificity relates to training adaptations derived specifically from the exercises performed and muscles involved. Reversibility is commonly referred to as the ‘use it or lose it’ principle. This means that if the overload is withdrawn, the adaptation will diminish. (Taylor et al, 2008). Components of training
Aneka is currently deemed high risk due to possible reoccurrences of angina on exertion and SOB therefore, the current rehabilitation programme, must take place in outpatient clinic where there should be plenty of resources available both in staffing and resuscitations equipment. The environment of the venue should be adequately ventilated. There should also be plenty of drinking water available for patient as required. There should be a rapid access to an emergency team in hospital and staffs should have regular practise in emergency drill and procedures and be competently trained on basic life-support and use of an automated defibrillator. (BACR, 1995) Exercise session must always start with a warm up period lasting between 10-15 minutes to avoid joint injuries and allow hemodynamic and physiology adaptations to exertion (Acevedo et al, 2011). It should include gentle movements to mimic those prescribed in the exercise activities, mobilisation of the joint and gradual pulse raise. This preparatory phase should end with stretching of the muscle groups to be used in the workout. For this particular patient, who currently has MET score of less than 3, a pulse raise program would include exercise performed mostly on the spot:
Marching on the spot
Neck turns to left/ right and side bends
Step to side/back. Then front/back
Side trunk bends
Toes tap forward/back
Heel tap forward/back
To increase pulse raise and body temperature, the pace/speed of these movements can be increased. Metabolic demands can be increased by involving larger muscles groups, e.g. Knee raise, or side steps.
The main objective of exercise prescription in CR is to improve functional capacity and endurance (BARC, 1995). The recommendation devoted to this phase is therefore aerobic or rhythmical activity, repetitive in nature and using large muscle groups, satisfying the intensity requirement (Acevedo et al 2001). The type of activities used in this part of the program can adopt either a continuous or interval approach. However, since interval training usually requires bouts of higher intensity work with recovery or rest periods which will allow more energy expenditure and larger volume of work, consequently leading to greater physiological changes. But for this patient at the present, it would not be the most appropriate approach based on her current history. Due to Aneka’s current cardiovascular status, she should be aiming to do bursts of exercise with recovery period in between repetition to accumulate a minimum of 20-30 mins exercises similar to the following:
Slow walking on flat surface.
Marching on spot and lifting the knees.
Very gentle cycling.
Step ups on low platform.