Careful Conditioning
By Janice P. Kehler, PT, MSC, MA
Monday June 8, 2009
With aging, there is an increased risk of cardiac arrhythmias and slowed heart rates that can affect a person’s exercise tolerance and quality of life. The pathologic histological changes in the heart’s conduction system can begin as early as age 60, resulting in fewer pacemaker cells in the sinoatrial node; increased fatty tissue surrounding the SA node and bundle of His; and increased fibrous tissue formation at the SA and AV nodes, which can block conduction. The result is a significant slowing of the heart rate, and for about 600,000 people worldwide, a pacemaker may need to be implanted.“Decline in physical function has a direct impact on a patient’s quality of life,” says Wendy Anemaet, PhD, PT, assistant professor in the school of physical therapy at Regis University, Colo. “These patients self-limit their activity due to declining oxygen carrying capacity, not unlike patients with rheumatoid arthritis who limit their activity due to pain. The end result is a loss of strength, function, and energy,” she says.Patients with arrhythmias may complain of weakness, dizziness, fatigue, or palpitations while exercising, and may feel as if they’re about to pass out. But to adequately address these symptoms, PTs need to have first established a baseline on each patient’s heart rate and blood pressure response, either during exercise or through submaximal exercise testing.Anemaet notes that monitoring vital signs is a cornerstone of PT practice in elderly populations. “It takes out the guessing,” she says. “When a client complains of these symptoms, you can determine if this is a sudden change from their baseline levels — a sign that a client needs to be referred to their physicians.”Counting on Recovery
After pacemaker implantation surgery, patients initially are restricted to light arm activities on the side where the pacemaker has been placed to allow for healing. The length of time varies according to each surgeon, but restrictions may stay in place for two weeks, according to Anemaet. During this time, patients should avoid excessive pressure over the incision, as well as learn to take their pulse and understand the range of heart rates that are acceptable for their type of pacemaker.“Increasing aerobic activity should be guided by the use of submaximal exercise testing,” Anemaet says. She recommends protocols that are specific to the type of activity that patients will use in their training, including treadmills, stationary bikes, and a six-minute walk test. For nonambulatory patients, a seated step test may be used instead. Training heart rates should be established at 50% to 70 % of the estimated VO2 max, and retesting should be performed to calibrate new training heart rates every four weeks.Throughout the recovery process, sudden changes in a patient’s signs and symptoms may indicate a malfunctioning pacemaker. Consequently, monitoring is essential in any PT or home health setting. Because blood pressure and heart rate are factors that reflect cardiac work during exercise, PTs can use the rate-pressure product to monitor exercise effects. The RPP is an indirect measure of myocardial oxygen consumption, determined by multiplying the systolic blood pressure by the heart rate. The RPP value should be below 27,000 for exercise to safely continue.Numbers Game
When initially beginning a cardiovascular conditioning exercise program, a target heart rate of 20 to 30 beats per minute above resting levels is appropriate, says Marsha Burt, MS, CES, an exercise physiologist in the cardiopulmonary rehabilitation program at the University of Minnesota Medical Center, Fairview in Minneapolis.But increasing the exercise capacity for patients with pacemakers is often complicated by medications such as beta-blockers, which blunt the heart’s response to exercise. In this instance, Burt teaches patients to rate their overall exertion level during exercise using the Borg Rate of Perceived Exertion Scale, a subjective scale that ranges from 6 to 20. Exercising at an RPE of 11 to 13 is considered a moderate level of exercise intensity that correlates with 40% to 60% of the heart rate reserve.However, Burt cautions that as patients progress, it is increasingly difficult to reach higher exercise intensities, and referral to a cardiac rehabilitation program should be considered. To enhance overall activity levels, she recommends using pedometers to track the number of steps walked each day. After a baseline assessment, Burt encourages patients to increase the number of steps walked by 10% each week.However the postoperative progression adds up, cardiac recovery is enhanced by staying on top of the numbers.
Janice P. Kehler, PT, MSC, MA, is a medical writer for the Gannett Healthcare Group. To comment, e-mail pteditor@gannetthg.com.
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