Implantable devices were introduced as life-saving equipment for millions of people suffering from coronary heart disease. Nowadays, not only tradi- tional antiarrhythmic pharmacological therapy has been shown to decrease sudden cardiac death, but also pacemakers and cardioverter defibrilla- tors have proved their value in the treatment of life-threatening rhythm disorders. In heart failure, cardiac resynchronisation therapy (CRT) and assist devices have recently demonstrated their importance, but no published data regarding phys- ical exercise or training are available yet. This chapter will mainly deal with physical exercise and rehabilitation in patients who have received an implantable cardioverter defibrillator. Cardiac rehabilitation in patients with assist devices or pacemakers will be discussed only briefly.
Assist and Pacemaker Devices
Non-pharmacological approaches to improve the morbidity and mortality in patients with moderate to severe heart failure have been sought for several decades. A solution has been found in cardiac resynchronization therapy (atrial-synchronized biventricular pacing), which was designed to stim- ulate the ventricle at multiple sites to improve the coordination of the contractions, and thus improve cardiac performance. In the numerous clinical trials, consistent benefits have been reported in quality of life, exercise capacity, and functional status. Up to now, no data on the effect of exercise training in CRT has been published, but the first randomised controlled trials, proving the addi- tional gain in exercise tolerance after a physical
training program, have been recently presented at 2 international meetings, EuroPRevent – Athens 2006 and at the World Congress of Cardiology – Barcelona 2006.1–3 However, the long-term benefit of this treatment regarding hospitalization and mortality has still to be established.4,5
Quality of life and impact on survival after implantation of the assist device were described by Grady et al.6Quality of life is rather good and stable from 1 month to 1 year after the implanta- tion. Items in the physical domain of quality of life (walking and dressing oneself) are associated with the risk of dying.
Improvements in exercise capacity as an immedi- ate effect of the implantation of the device have been reported, but as yet no training studies have been performed in this relatively new patient population.
The advanced current pacemaker devices treat brady- and tachyarrhythmias, sinus arrhythmias, and conduction disturbances by altering the lead wire of the pulse generator to supply adequate electricity for continuing the metabolic and phys- ical stimuli of the myocardial activity.
Research has documented that pacemaker therapy may reinstate regular exercise capability, reduce symptoms or abnormalities, and improve quality of life and survival.7 Pacemakers must be considered as implanted devices which may influence the reaction of heart rate. This is the major concern when developing basic guidelines for exercise programs. Cardiac re- habilitation for patients with a pacemaker is feasible when the rate-response setting of each patient is adapted correctly, avoiding functional destruction by insufficient pacing rates. Greco et al. described the use of the oxygen pulse
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L. Vanhees, S. Beloka, M. Martens, and A. Stevens
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reserve (mL O2/beat, measured during an exercise test) and the pacing rate, in patients with pacemakers, in order to tailor the rate response in a cardiac rehabilitation program. After a period of 2–7 months, there was an average improvement in peak oxygen consumption of 23%.8 No general guidelines for physical training and rehabilitation have been described yet for the pop- ulation of patients with a pacemaker.
Implantable Cardioverter Defibrillators
The implantable cardioverter defibrillator (ICD) has evolved to be the golden standard therapy for patients at high risk for malignant ventricular arrhythmias or sudden cardiac death (SCD). These patients include those who have survived a life- threatening dysrhythmic event (secondary preven- tion) and those who suffer from cardiac disease who are symptomless but at risk for such arrhyth- mias (primary prevention). In addition, new ICDs also provide full featured dual chamber pacing,and could treat atrial arrhythmias and congestive heart failure by means of biventricular pacing.9
The ICD is an external device implanted in the recipient’s chest, designed to deliver pacings and shocking pulses to the myocardium. By delivering an electric shock, ventricular tachycardia/fibrilla- tion and SCD can effectively be aborted. The AVID (Antiarrhythmics Versus Implantable Defibrilla- tors) trial was the first large trial that showed the superiority of the ICD compared to antiarrhyth- mic drugs in terms of increasing overall survival in patients who had survived a previous event.10
Psychosocial Aspects and Quality of Life
It is logical to think that the implantation of a life- saving device would make the patient confident of the improved life expectancy and relieve the fear of sudden death. But living with the possibility of receiving a defibrillating shock at any time can be emotionally devastating. Compared to the general population, quality of life and psychoso- cial adjustment are poor in patients with ICDs.11,12 According to Sears et al., ICD-specific fears and symptoms of anxiety are the most common symp-
toms experienced by patients with ICD.11More- over, 13–38% of these patients experience diag- nosable levels of anxiety. ICD-specific fears include fear of shock, fear of device malfunction, fear of death, and fear of embarrassment. The health-related quality of life is also negatively associated with fear of exercise.12
Social and working life can also be negatively influenced as there is limitation of action, due to the fear that stress or emotions might alert the device. Others may worry about their body image or avoid exercise and sexual activity because of fears of arrhythmias and discharge of the ICD.13 In some countries, driving is even, at least tem- porarily, prohibited.14,15
Also partners of ICD patients report feelings of helplessness and uncertainty about what to do if, or when, the ICD discharges. They worry about the reliability of the ICD and about their own position if their partner should die.16 This may commonly result in overprotection of the ICD patient, and partners often restrict or restrain them from doing physical activities.
The importance of involving, educating, and equipping partners with the relevant information and skills so that they can empower and support the patient to reach informed decisions should not be underestimated. In the absence of such inter- ventions, the potential for misconceptions, mis- guided beliefs, and marital conflicts can increase, perpetuating further uncertainty, fear, and loss of control as well as precipitating physical symptoms.17
Recent studies report the psychological benefits for patients with ICDs after psychological inter- vention or comprehensive cardiac rehabilitation.
Kohn et al. studied cognitive behavioral therapy in patients with ICDs in a randomized controlled trial. They concluded that cognitive behavioral therapy was associated with decreased levels of depression and anxiety, and increased adjustment, particularly among those patients who received a shock.18Fitchet et al. reported decreased anxiety scores after 12 weeks of comprehensive cardiac rehabilitation, including psychosocial counseling, in a randomized controlled trial.19
These data demonstrate the importance of planning and organizing psychosocial support for patients with ICDs in comprehensive cardiac rehabilitation.
Exercise Testing
The design of an exercise program should always be preceded by a maximal or symptom-limited exercise test.20Despite the fear of patients with an ICD and the risk of harmful and threatening symptoms, the exercise test has a key role in the evaluation of arrhythmias, the ICD device, peak heart rate and exercise tolerance, and medical therapy.
The testing protocol should be a standard graded exercise tolerance test on a motor driven treadmill or cycle ergometer with assessment of ECG, blood pressure, and oxygen uptake. The assessed peak oxygen uptake is the most accurate measure of functional capacity. It can also be estimated by exercise hemodynamic data or the external workload that was achieved. A submaxi- mal test (terminating the test at a given percent- age of predicted maximum heart rate) is not recommended because medications affect the age- predicted maximum of the heart rate, it would only give an estimate of the actual exercise toler- ance, and it would not give the opportunity to evaluate the reactions of cardiac rhythm and the ICD on maximal exercise.
The participant elicits a maximum cardiorespi- ratory response by continuing the exercise test till
exhaustion or fatigue. In some studies, the point when the patient reached a heart rate threshold of cut-off point minus 10 to 30 beats was one of the endpoints of the test, in order to avoid discharge of the ICD.19,21,22 However, Lampman and Knight state that when the cut-off point is situated below the age-predicted maximum, the ICD should be temporarily switched off during the exercise test.20 This way, the patient can reach his or her true maximum without being at risk for inappropriate shocks. It seems more logical to perform a maximal exercise test with the ICD activated, because that way you can gather information about the reaction of the cardiac rhythm and the ICD to exercise. The result of the exercise test can give confidence that exercise at a predetermined level is safe and can be performed in the con- trolled environment of cardiac rehabilitation (consistent with the report19of Fitchet et al.).
Some sources are available for exercise testing in patients with an ICD23–25 or in patients with malignant ventricular arrhythmias.26–28There are few studies that give accurate data about the results of exercise testing and complications in patients with ICDs or ventricular arrhyth- mias.19,21,22,26,27A summary can be found in Table 50-1. From this table, it can be concluded that there were few complications during exercise
TABLE50-1. Exercise testing in patients with malignant ventricular arrhythmias or ICD
Authors Patients Exercise testing Endpoints Complications during the test
Young et al., 1984 263 – arrhythmias Maximal ET (treadmill) Exhaustion 24 arrhythmias
stage 1: 1 mph at 0 degrees 17 prolonged VTs
(↑ elevation/2min) stage 6: 3.0 mph at 14 degrees
Allen et al., 1988 64 – arrhythmias Maximal ET (treadmill) Fatigue 5 sustained VTs
Maximal exercise test (86%) Dyspnea
Modified low-level (14%) Symptomatic arrhythmia
Vanhees et al., 2001 8 – ICD Maximal ET (bicycle) Exhaustion 1 VT without ICD intervention or
20 W + 30W/3min HR threshold (= detection rate adverse clinical manifestations
− 30 beats)
Fitchet et al., 2003 34 – ICD Symptom-limited ET RPE = 7/10 = hard effort No discharges during ET (treadmill) HR = 75% of the age-adjusted
1.6 km/h + 0.8/2min until maximum
7.2 km/h HR threshold (= detection rate Constant gradient 10% − 10 beats)
Vanhees et al., 2004 92 – ICD Maximal ET (bicycle) Exhaustion: 100% 1 VT requiring over-pacing 20 W + 20W/min HR threshold (= detection rate
− 20 beats): 0%
ET: exercise test; HR: heart rate; RPE: rate of perceived exertion scale; VT: ventricular tachycardia.
testing in patients with ICDs. In the last and largest study in patients with ICDs,19all patients stopped the exercise test because of exhaustion and the predetermined target heart rate of cut-off minus 20 beats was not reached. Most of the patients received drugs with negative chro- notropic properties.
In conclusion, it can be stated that maximal or symptom-limited exercise testing in ICD patients with optimal pharmacological treatment is safe and feasible, but should only be performed in a professional and medical environment with con- tinuous emphasis on safety measures.
Exercise Training
Three reports described general experiences and some guidelines for exercise training. Two of them discussed exercise training in patients with malig- nant ventricular arrhythmias,24,25 and one publi- cation described the prescription of exercise training specifically for patients with an ICD.23To the present, there are only three studies with accu- rate published data that have examined the influence of exercise training in ICD patients.19,21,22 The components and results of the exercise pro- grams in these studies are presented in Table 50-2.
Taking these results into account, some adapted recommendations for exercise training can be
formulated. An ambulatory, supervised exercise training program should contain three training sessions a week for at least 12 weeks. The sessions should have a duration of 90 minutes and consist of a warming up, the main exercise part, and a cooling down. The warming up is a period of calm physical activity of 5–10 minutes, inducing the patient into cardiovascular adjustments and lim- iting the risk of arrhythmias or other cardiovas- cular complications. It can include low-intensity aerobic exercise and flexibility exercises. The cooling down is a mild exercise or relative rest of 5–10 minutes, protecting the patient from possi- ble complications in the early recovery period and to help the cardiovascular system to return slowly to a resting condition.
The main part of the training session can contain aerobic exercises like walking, jogging, cycling, arm ergometry, rowing, predominantly isotonic callisthenics. The exercise intensity is individually determined for every patient, based on the participant’s clinical status and the initial exercise tolerance assessed by the baseline exer- cise test. The interval for training heart rate (HR) is calculated, using the formula of Karvonen:
HRtraining= HRrest+ 60–90% (HRpeak– HRrest). Fur- thermore, ICD patients are instructed not to surpass the upper heart rate threshold, which was determined in the studies mentioned above as
TABLE50-2. Components and results of exercise programs for patients with an ICD
Author Study plan No Training characteristics Exercise tolerance Complications during training
Vanhees et al., 2001 3 months 8 TF: 3 sessions/week Peak VO2:+24% 1 asymptomatic VT with ICD
comprehensive CR TD: 90 min/session intervention
with aerobic exercise TI: (HRrest + 60–90% (HRmax −
training HRrest)) with upper limit of
HR = detection rate − 30 beats
Fitchet et al., 2003 12 weeks 16 TF: not specified Exercise time: No ICD discharges
comprehensive CR TD: not specified +16%
with exercise training TI: HR of 60–75% of age adjusted maximum with upper limit of HR = detection rate − 10 beats
Vanhees et al., 2004 3 months 92 TF: 3 sessions/week Peak VO2:+17% 3 ICD discharges after VT:
comprehensive TD: 90 min/session patients dropped out of
CR with aerobic TI: Leuven: (HRrest + 60–90% the study
exercise training (HRmax − HRrest)) with upper 1 ICD discharge after VT
limit of HR = detection rate 1 VT without intervention
− 20 beats 1 inappropriate shock
TI: Leiden: 50–80% max intensity
CR: cardiac rehabilitation program; TF: training frequency; TD: training duration, TI: training intensity; HR: heart rate; VT: ventricular tachycardia.
detection rate minus 10, 20 or even 30 beats. The cut-off rate is determined for each individual depending on the slowest ventricular tachycardia and the exercise physiologist is responsible for knowing the cut-off rate for the device of each patient who participates in the rehabilitation program. It is recommended to increase the exer- cise intensity progressively, based on feedback from the patient and on the results of further exer- cise tests.29Based on our experience, we recom- mend an upper heart rate threshold during exercise training of the detection rate minus 20 beats/min.
Patients with a history of ventricular arrhyth- mias provoked by ischemia or heart failure exac- erbations should also pay attention to the body position. It is recommended to perform exercise in an upright position rather than prolonged supine activities, because of lower left ventricular filling pressures in the upright position.23
The possibility of ECG monitoring should be available in the training room. During the first training sessions, the ECG monitoring assures confidence, freedom of movements, and safety from shocks that may occur during exercise. It can give valuable information about heart rhythm, and it can make the patient confident in the safety of exercise. When there are no problems during the first sessions, other heart monitoring devices (e.g. Polar) give enough information to train safely. In the absence of a heart rate monitor, patients should palpate their peripheral pulse reg- ularly during and after the exercises, in order to determine if the pulse is within the limits of the target heart rate.23
The rehabilitation environment should be light and airy and adequately equipped in order to encourage exercise. Although there is a specific need for close supervision and electrographic monitoring during exercise activities, the same safety measures should be taken as in cardiac rehabilitation programs for a general population of cardiac patients. These safety considerations are already well described.20
Exercise training may provoke limited ventric- ular tachycardia in patients with ICDs during training and/or at the end of the training exercise program. The diagnosis of ventricular tach- yarrhythmia occurs when the heart rate exceeds the programmed cut-off rate and consequently
the therapy is delivered by the ICD. After a shock has been delivered, the ICD is interrogated for the next 24 hours in order to locate the reason and to make adaptations to the ICD therapy program.
The rehabilitation program should be continued, if necessary with an adapted exercise prescrip- tion, as soon as the patient is clinically stable and feels confident to restart training.
There is great emphasis on the individualiza- tion of risk factor management, a multidiscipli- nary approach to ensure provision of optimal care and the need for life-long exercise participa- tion. Cardiologists, physicians, exercise physi- ologists, dietitians, psychologists, and other professionals should collaborate to manage risk reduction through follow-up techniques, includ- ing office or clinic visits, attendance of cardiac rehabilitation sessions and mail or telephone contact to show interest in the patient and to keep the patient motivated for participation in the program.
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