What is cardiac rehabilitation?

Indications and Procedures

Cardiovascular disease (CVD), or heart
disease, is the leading cause of death and disability in most of the industrialized nations of the world. For those persons who survive a cardiac event, discharge from a hospital or medical setting without further assistance may lead to financial, physical, and mental incapacity.

Just as interventional procedures and medical care are important for the initial treatment of acute cardiac events, such as a myocardial infarction (heart attack
) or angina (chest pain
), cardiac rehabilitation influences long-term morbidity and mortality. Such preventive cardiology assists persons with CVD in three main areas: education, behavior modification, and patient and family support. The two primary goals of the rehabilitation program are to help increase the patient’s functional capacity (the ability to perform activities of daily living) and to counteract or arrest the patient’s disease process using a multidisciplinary educational approach.

To provide direction in prevention and rehabilitation, research studies have clearly defined several modifiable risk factors for heart disease, which are presented to patients. Among the most significant are smoking, high serum
cholesterol, hypertension, physical inactivity and overweight, diabetes, and depression. Assistance with education about and modification of these risk factors, through risk factor counseling and participation in physical activity, is provided in modern cardiac rehabilitation programs.

Methods for providing education on risk factor modification can vary greatly from program to program but may include such means as didactic lecturing, slide presentations, printed material for patients to read, demonstrations (such as cooking and stress reduction techniques), providing loaner books, and one-on-one counseling.

The exercise portion of the cardiac rehabilitation is most often the time-consuming element of the program. It involves controlling and monitoring four major variables: mode (type of activity, such as bicycling, walking, or stair-stepping), duration (length of time the patient exercises), frequency (number of times per week that exercise is performed), and intensity (exertion level of the patient, usually assessed by the heart rate response).

To become involved in the cardiac rehabilitation program, a patient is initially screened by a physician, nurse, or other clinical specialist and directed to the appropriate level (or phase) of intervention.

There are three to four clinical phases involved with cardiac rehabilitation, as various groups categorize them differently. Phase 1 occurs while the patient is still in the hospital. It begins when the patient’s condition is stabilized, sometimes as soon as forty-eight hours after the coronary event or procedure. This phase can begin in the coronary care unit (CCU) or the intensive care unit (ICU). Phase 1 incorporates several disciplines, including physical therapy, nursing, psychiatry, dietetics, occupational therapy, and exercise science. It is designed to prevent the deleterious physiological effects of bed rest.

The physical components of this phase include maintaining a range of motion and gradually returning to activities of daily living. Patients gradually advance through stages until they are able to walk up to 200 or 400 feet. Before discharge, patients are encouraged to walk up and down one flight of stairs. Stair climbing is done while accompanied by a physical therapist or other clinician who monitors heart rate and blood pressure. The level of exertion during the early portion of this phase is normally 1 to 2 metabolic equivalents (METs). Thus, in phase 1, the mode of exercise focuses on motion (sitting, standing, and finally walking), the frequency is seven days per week, the duration of exercise is usually five to ten minutes at a time, and the intensity of activity should not cause the heart rate to exceed twenty beats above the resting rate while standing.

For coronary artery bypass graft (CABG) patients who have not experienced a myocardial infarction, progress during this phase is usually faster than for heart attack patients. Percutaneous transluminal coronary angioplasty (PTCA) patients may receive only a few days of rehabilitation, as they are usually discharged from the hospital sooner than heart attack or CABG patients.

The mental components of phase 1 include risk factor modification education and an introduction to rehabilitation concepts. Risk factor education at this point provides a good foundation for the basic concepts that will be explained during the education program in phase 2. For those patients who are appropriate candidates for a phase 2 program, information on that phase is then provided.

Phase 2 customarily begins within three weeks of discharge from the hospital and lasts for four to twelve weeks. During phase 2, patients are exposed to a level of exertion commensurate with several criteria: the patient’s clinical status (stable or unstable, depending on whether the patient is experiencing problems related to the disease); the patient’s functional capacity, or fitness level; orthopedic limitations, such as muscle or joint problems; the goals for functional capacity (what tasks the patient wants to be able to perform); and any other special circumstances or situations.

In a given phase 2 program, there are a variety of patients, all with varying levels of physical fitness. Through variations in the mode, duration, frequency, or intensity of exercise, these differing levels of fitness can be accommodated. A variety of exercise modes are presented in the phase 2 program, including walking, stationary cycling, stationary rowing, simulated stair-climbing, water aerobics, swimming, and upper body ergometry. The exercise frequency for this phase is three to five days per week, the duration consists of twenty to forty-five minutes of continuous aerobic activity, and the intensity should produce a heart rate that is 60 to 85 percent of the symptom-limited maximal heart rate. Muscle-strengthening and flexibility exercises may also be recommended. Exercises are monitored by an exercise specialist or other sports medicine clinician and a cardiovascular fitness nurse. Exercise intensity is determined in most cases by heart rate and may be monitored by electrocardiogram (EKG or ECG) telemetry on a number of patients simultaneously.

One of the interesting psychological components to phase 2 cardiac rehabilitation is that most programs are arranged so that new participants are coming into the program as participants who have been in the program for several sessions are leaving. Newer participants are able to identify with those already in the program as a result of similarities in cardiac experiences. It has been suggested that this identification decreases the anxiety level of a patient who is just becoming involved in the program.

Patients move into phase 3 of cardiac rehabilitation, a community-based outpatient program, when cardiovascular and physiological responses to exercise have been stabilized and the patient has achieved the goals initially set. Phase 3 is generally considered to be an extended, supervised program that usually lasts from four to six months but can continue indefinitely.

Participants in phase 3 programs become more involved in and responsible for their own exercises. Typically, these programs do not include EKG monitoring. Individuals are given more responsibility with respect to maintaining their own heart rates in their training heart rate range. Usually, an exercise specialist, nurse, or physician is available to oversee the exercises. The mode, frequency, duration, and intensity of exercise in this phase is similar to that of phase 2.

Phase 4 is a maintenance program. Although many rehabilitation settings label this a phase 3 program, the phase 4 program is considered the longest-term, ongoing phase and is of indefinite length. Many phase 2 cardiac rehabilitation program graduates remain in phase 3 or phase 4 programs for years. The mode, frequency, duration, and intensity of the exercise program for phase 4 are also similar to those of phase 2.

Uses and Complications

Traditionally, cardiac rehabilitation has been recommended for individuals convalescing from myocardial infarctions or heart surgery (CABG, PTCA, or valve replacement). More recently, the eligibility for cardiac rehabilitation has been extended to include heart transplant recipients and others with cardiac-related illnesses.

Improvement of work capacity is one of the goals of cardiac rehabilitation. The mechanisms involved in increasing work capacity (aerobic capacity and maximal oxygen consumption) normally include increases in both central (cardiac output, stroke volume, and heart rate) and peripheral (muscle changes, atrioventricular oxygen difference) adaptations. Nevertheless, this does not preclude patients with reduced left ventricular (LV) function from participation in a medically supervised exercise program. For the reduced LV function patient, improvement in exercise tolerance can occur; this improvement may be attributable mainly to peripheral adaptations.

For the low-risk patient, cardiac rehabilitation may seem unnecessary since unsupervised exercise programs have been demonstrated to be safe and effective and to improve exercise capacity. For healthy lifestyle modification to take place, however, the educational component of cardiac rehabilitation may provide the patient with invaluable knowledge. To reduce the chance of recurrence or severity of a myocardial infarction in an effective manner, a healthy lifestyle is encouraged. Additional potential benefits of participation include improved self-esteem, positive mental attitude, and decreased anxiety and depression.

Low-risk patients, who account for about one-third to one-half of heart attack patients and about three-quarters of CABG patients, have a first-year mortality of less than 2 percent. Moderate-risk patients have a first-year mortality rate of between 10 percent and 25 percent. High-risk patients’ mortality rates are greater than 25 percent. While cardiac rehabilitation is not effective in all circumstances, proper assessment of an individual’s clinical situation and competent administration of the program can optimize the outcome for participants.

Increasing numbers of cardiac rehabilitation programs are accepting unconventional patient populations. These patients now include heart transplant recipients, congestive heart failure patients, individuals suffering from ischemic heart disease, and those with arrhythmias and/or pacemakers.

Although most of the prescribed exercise regimens for these patients parallel those for the conventional cardiac patient, there are subtle differences. In the heart transplant population, for example, heart rate response differs from nontransplant patients. The adjustment of heart rate to various workloads lags in acute heart transplant recipients; that is, the heart rate does not increase as rapidly as it does for normal people. To accommodate this difference, researchers have suggested that, in place of heart rate response, clinicians use a “rating of perceived exertion” scale to monitor the patients’ responses to exercise.

Even patients who have orthopedic limitations, such as arthritis or chronic injuries, may be accommodated in the exercise portion of the cardiac rehabilitation program. Exercises can be adjusted to allow participants to derive cardiovascular benefits without causing them unnecessary discomfort.

Although cardiac rehabilitation is safe in general, several factors may emerge during graded exercise testing (a screening for entry into a cardiac rehabilitation program) that can identify those patients who may be at increased risk. These factors include a significant depression or elevation of the S-T wave segment from a resting EKG, angina, extensive left ventricular dysfunction and severe myocardial infarction, ventricular dysrhythmias, inappropriate blood pressure response to exercise, achieving a peak heart rate of fewer than 120 beats per minute (if not taking a negative chronotropic medication, which slows down the heart rate), and a functional exercise capacity of fewer than 4 to 5 METs. Inclusion in one of these categories does not preclude participation in a cardiac rehabilitation program, but it may warrant specific exercise guidelines and close monitoring.

Among the criteria for exclusion from a cardiac rehabilitation program are unstable angina, acute systemic illness, uncontrolled arrhythmias, tachycardia, diabetes, symptomatic congestive heart failure, a resting systolic blood pressure over 200 millimeters of mercury (mm Hg) or a resting diastolic blood pressure over 110 mm Hg, third-degree heart block without a pacemaker, and moderate to severe aortic stenosis.

For those who meet the criteria for inclusion in a cardiac rehabilitation program, risk stratification (low, moderate, or high) may be employed. This allows an appropriate amount of supervision to be in place based on each patient’s goals and condition. Clinical observations and tests allow each patient to be assessed individually. Within each phase, levels of risk may be established. Various proposals have been made for risk stratification prior to entry into a cardiac rehabilitation program, including stratification based on several factors: the degree of left ventricular dysfunction, presence or absence of myocardial ischemia, extent of myocardial injury, and presence of ventricular arrhythmias.

Some of the most widely examined noninvasive assessment tools include the extent of QRS wave abnormalities on a resting EKG and the results of exercise stress testing, twenty-four-hour ambulatory EKG monitoring, radionuclide ventriculography, and echocardiography. A combination of these test results may be used to determine the course of action provided to an individual.

As with any effective therapy, exercise as a form of cardiac rehabilitation is neither without hazard nor always beneficial. If appropriate clinical guidelines are utilized, however, the benefit-risk ratio can be very favorable. The low incidence of cardiac-related adverse events during participation in outpatient cardiac rehabilitation programs is probably attributable to improved risk stratification, the use of appropriate medical and surgical therapies, and improved exercise guidelines. On the rare occasions when cardiac events occur, reports have indicated that up to 90 percent of all patients with exercise-related cardiac arrest are successfully resuscitated when the patient experiences the event in a properly equipped and supervised program.

Perspective and Prospects

Until the 1940s, patients recovering from acute myocardial infarctions met with restriction of physical activity, bed rest, and psychological apprehension about exertion. Over the next two decades, the deleterious physiological effects of prolonged bed rest began to be described. During this time, a few investigators were beginning to encourage early treatment of the patient who has experienced an acute heart attack, including armchair work and walking within four weeks of the acute event.

In the 1950s, British physician Jeremy Morris and his colleagues conducted research that initiated interest in the relationship between coronary artery disease (CAD) and a sedentary lifestyle. In this study, he found that London bus drivers had twice the risk of developing CAD than their more physically active bus conductor counterparts. In addition, among those drivers and conductors who had experienced a heart attack, the drivers were twice as likely as the conductors to die either during or within two months of their heart attack.

During the 1960s, the beginnings of what are now considered cardiac rehabilitation programs incorporated exercise training on a somewhat limited basis. Restricted exercise regimens began a few weeks after cardiac events and increased in intensity on a very gradual basis. Generally, the patient population considered appropriate for such programs consisted of those individuals who had experienced uncomplicated myocardial infarctions. Some risk factor modification education was initiated, but not on a large scale primarily because data supporting improved patient outcomes were not proven.

Soon afterward, the On Ward program, designed to begin on the tenth day following a heart attack, was introduced based on work by William P. Blocker Jr. and colleagues. In 1971, J. M. Kaufman suggested that rehabilitation of uncomplicated myocardial infarction patients could begin as early as two days after the heart attack. At this time, many hospitals had some form of cardiac rehabilitation program; most of them, however, consisted almost exclusively of exercise training. This approach addressed the physiological changes necessary for improving the functional capacity of the patients but did not address long-term behavior modification and education.

In 1986, Ralph S. Paffenbarger Jr. published a prominent exercise and heart disease study. In his study using 16,936 Harvard University alumni from thirty-five to seventy-four years of age, he validated the concept that physical inactivity is independently related to CAD. In the next seven years, various research on a total of more than 32,000 people was done confirming that hypothesis.

Also in 1986, another group of physicians and researchers described some of the deleterious effects of bed rest, including decreased physical work capacity, decreased cardiac output, skeletal muscle wasting, orthostatic hypotension (abnormally low blood pressure upon standing), decreased blood volume, loss of muscular strength, and reduced pulmonary function. Exercise was shown to be beneficial in reducing some of these effects.

Based on the information outlined above, a multifactorial approach to cardiac rehabilitation has been undertaken in order to provide patients with the information and skills necessary to alter their lifestyles. This approach includes education, in the form of lectures, handouts, videos, and informal discussions; behavior modification, by way of regularly scheduled, supervised aerobic exercise programs and nutritional counseling; and support, by means of cardiac rehabilitation classroom meetings and support groups. With this increased scope of care for the cardiac patient, some institutions are providing cardiac patients with access to a broader base of clinicians. This group may include physicians, nurses, exercise specialists or physiologists, dietitians, physical therapists, social workers, psychologists, and occupational therapists. Even with all these components in place, however, exercise training remains the focal point of most contemporary cardiac rehabilitation programs.

Recent studies using meta-analysis have substantiated the hypothesis that exercise-based cardiac rehabilitation programs that include risk factor/behavior modification significantly decrease mortality. Decreasing the number and/or magnitude of the known risk factors for heart disease has been shown to effect a significant improvement in the cardiovascular risk profile for these patients. Research has demonstrated the fact that, although various degrees of CAD may remain after participation in a cardiac rehabilitation program, patients can achieve a sense of well-being. For some patients, this benefit alone may improve health and reduce the financial burden often associated with postinfarction convalescence.

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