Circulatory and symptomatic effects of physical training in patients with coronary-artery disease and angina pectoris

Exercise performance of the high risk acute myocardial infarction patient after cardiac rehabilitation

Sixty-five subjects with a recent acute myocardial infarction (AMI), 50 men and 15 women aged 39 to 79 years (mean 62 +/- 9), were entered into a 12-week phase II cardiac rehabilitation program. Group I subjects were those with an ejection fraction greater than 40% (mean 56) and group II subjects were those with an ejection fraction less than 40% (mean 28). Subjects were further classified into those with or without myocardial ischemia (Ia, IIa and Ib, IIb, respectively) based on a treadmill stress test before entry. Work performance during the training sessions was similar for all subgroups, although group IIb had the lowest values for work rate and time of exercise for each individual activity. Subgroup analysis, as determined by a pre- and postprogram treadmill stress test, showed there was no significant difference in time of exercise, peak oxygen consumption and change in submaximal heart rate (decrease) for groups Ia, Ib or IIa. However, group IIb had poor performance in time of exercise (delta = 2 +/- 2 minutes), peak oxygen consumption (delta = 3 +/- 5 ml/min) and submaximal heart rate (delta = 0.4 +/- 17 beats/min) compared with the 3 other subgroups. These subjects also did not demonstrate an improvement of these values in the posttraining period. Patients who have had AMI and have both significant left ventricular dysfunction and myocardial ischemia did not have an adequate training response after 12 weeks of a formal phase II cardiac rehabilitation program.(ABSTRACT TRUNCATED AT 250 WORDS)

Improvement of treadmill capacity and collateral circulation as a result of exercise with heparin pretreatment in patients with effort angina

It has been demonstrated in animal experiments that heparin accelerates the coronary collateral development induced by repeated coronary occlusion. We used this effect of heparin for the treatment of patients with stable effort angina. In 10 patients, treadmill exercise was performed according to standard Bruce protocol twice a day for 10 days. A single intravenous dose of heparin (5000 IU) was given 10 to 20 min before each exercise period. Exercise with heparin pretreatment increased the total exercise duration from 6.3 +/- 1.9 (SD) to 9.1 +/- 2.2 min (p less than .001) and the maximal double product (DP) from 18,900 +/- 5100 to 25,500 +/- 6800 mm Hg.beats/min (p less than .001). The DP at the onset of angina was also increased by 35% (p less than .01) and the DP at which ST depression (0.1 mV) first appeared was 19% (p less than .05) greater after treatment. Repeat coronary cineangiography revealed an increase in the extent of opacification of collaterals to the jeopardized myocardium. In an additional six patients, treadmill exercise was performed with no medication twice a day for 10 days. All of the above-mentioned variables of treadmill capacity remained unchanged, despite 20 exercise periods without heparin pretreatment. Thus, heparin accelerates exercise-induced coronary collateral development by promoting angiogenesis. The development of such a therapeutic modality will open a new field for the treatment of patients with ischemia.

Comparison of high- and low-intensity exercise training early after acute myocardial infarction

The effects of the intensity of exercise training on cardiorespiratory variables were investigated in a consecutive series of men with recent (median 8 weeks) acute myocardial infarction. Forty-five patients were randomly assigned either to a high- (65 to 75% maximum oxygen consumption rate [VO2max]) or to a low-intensity (less than 45% VO2max) exercise group. Patients engaged in medically supervised aerobic training 3 sessions a week for 12 weeks. With training, mean VO2max significantly increased by 11% (2.09 to 2.31 liters/min) within the high group and by 14% (1.93 to 2.21 liters/min) within the low group. Differences between groups were not statistically significant. Both groups also had comparable changes in heart rate, blood pressure and double-product at submaximal and maximal workloads. Analysis of blood lipids revealed that both groups experienced a significant increase in high density lipoprotein cholesterol. There were no significant changes in total serum cholesterol or triglycerides. These findings suggest that within an unselected population of patients after acute myocardial infarction referred for cardiac rehabilitation, low- and high-intensity exercise training produces relatively similar changes in cardiorespiratory variables during the initial 3 months of exercise training.

Cardiovascular effects of training for a marathon run in unfit middle aged men

The effects of a 30 week exercise programme on serum lipid values, blood pressure, and cardiac function were assessed in a group of sedentary men aged 35-50 training for their first marathon. Mean serum cholesterol concentration (n = 33) fell by 12% from 6.54 (SE 0.18) to 5.76 (0.15) mmol/l (mean fall 0.78 mmol/l; 95% confidence interval 0.52 to 1.04 mmol/l), serum triglyceride concentration (n = 33) by 22% from 1.56 (0.17) to 1.21 (0.09) mmol/l (mean fall 0.34 mmol/l; 95% confidence interval 0.12 to 0.56 mmol/l), and mean blood pressure (n = 27) by 10% from 102 (2) to 92 (2) mm Hg (mean fall 10 mm Hg; 95% confidence interval 7 to 13 mm Hg). These changes were not explained by changes in body composition. Peak exercise left ventricular end diastolic volume (n = 16) increased with training; as a result of this and an increased exercise left ventricular ejection fraction peak exercise cardiac output increased from 19.9 (1.2) to 23.1 (3.0) l/min (mean rise 3.2 l/min; 95% confidence interval 1.5 to 5.0 l/min). Maximum oxygen consumption increased from 33.9 (1.6) to 39.0 (1.3) ml/kg/min (mean rise 5.0 ml/kg/min; 95% confidence interval 1.8 to 8.2 ml/kg/min). This study showed favourable effects on coronary risk factors and cardiac function and supports the place of regular exercise in coronary prevention programmes.

Exercise conditioning in the elderly coronary patient

We compared conditioning effects of a supervised exercise program in 100 elderly and younger patients with a recent coronary event. Twenty-one patients were greater than or equal to 62 years of age (mean, 65 years) and 79 were less than or equal to 61 years of age (mean, 48.7 years). While the elderly patients attained a lower peak exercise intensity on entry and on completion of the exercise protocol, they obtained a similar relative training benefit as the younger patients. Peak exercise intensity increased 68% in each group and submaximal (five METS) heart rate-blood pressure product decreased 27% in the older patients and 26% in the younger patients. Rate of entry into our program was substantially lower in the elderly patient group, 19% v 57% in younger patients (P less than 0.001) despite a similar inhospital recruiting effort. Thus, although elderly coronary patients obtain similar training benefits as younger patients, they are less likely to participate in a program designed to decrease cardiac disability.

Who's afraid of angina pectoris? Separating the symptom from the marker

100 cardiologists were asked for their views on the risk associated with an episode of exertional angina in patients with stable angina. 58% thought that such an episode carried some risk of permanent damage or death, and 78% advised their patients to avoid anginal pain. In contrast, exercise studies done during the evaluation of anti-anginal drugs indicate that exertional angina can be provoked frequently and repeatedly without apparent risk, and other studies have shown that repeated exercise to the onset of angina is not only safe but improves exercise tolerance. Epidemiological investigations suggest that sudden death and myocardial infarction do not commonly occur during exertion, and our knowledge of pathology indicates that both events are usually caused by acute coronary thrombosis. Many physicians seem to treat the symptom of angina because they are unduly motivated by fear of the underlying potentially fatal disease for which angina is a marker. Such an attitude will tend to cause undue anxiety among patients, will lead to unnecessary restriction of patients' activities, and may result in excessive invasive treatment of mild angina.

Principles of exercise prescription for patients with coronary artery disease

Exercise performance is determined by the interaction of many systems. Cardiac disease, non-cardiovascular pathology, physical training, and the hemodynamic response to the type of exercise the patient wants to perform should all be considered when developing an exercise prescription. There are two stages for deriving a complete exercise prescription, determination of optimal exercise intensity from an exercise test and adoption of the recommendation to include other forms of exercise. The recommendation is usually based on a target oxygen consumption or a target heart rate derived from a treadmill test, but both of these methods may be of limited effectiveness. Ventilatory measurements during exercise, which reflect metabolic changes, are a useful adjunct. The exercise prescription must be individualized to the patient's needs, and may have to be modified so that exercise intensity remains within acceptable limits.

Cardiac adaptations to training: relevance to angina pectoris

Exercise training has for many years been suggested as a useful adjunct to medical therapy for patients with ischaemic heart disease. While its popularity amongst the general public continues to grow, limitations in our ability to assess its effects on the heart have meant that, as cardiologists, our desire to encourage this popular upsurge in physical activity has been tempered by our inability to provide convincing evidence of its value to our patients. In particular the role of exercise in the rehabilitation of patients with angina pectoris is as yet unclear. This review addresses this question and states what has been proven to date and also the questions which remain to be answered. It also suggests some reasons why we have failed to provide answers so far, and ways in which new technology may be used in the future. Studies in animals, asymptomatic humans, and patients with ischaemic heart disease have demonstrated that training reduces the resting heart rate and double product of heart rate times blood pressure at any given level of exercise. This has the benefit of reducing myocardial oxygen consumption during exercise. There is also evidence that it increases end-diastolic volume and left ventricular wall thickness. Evidence for an increase in maximal myocardial oxygen consumption in angina is limited to one or two studies showing an improved maximum double product and to the occasional patient proven by echocardiography or nuclear studies to increase ejection fraction by training. Better selection of patients and use of new imaging techniques should provide further information in the near future.

Learned control of heart rate during exercise in patients with borderline hypertension

Twelve patients with borderline hypertension [less than or equal to 21 X 33/12.6, greater than or equal to 18 X 6/12.0 kPa (less than or equal to 160/95; greater than or equal to 140/90 mm Hg)] participated in an experiment aimed at testing whether they could learn to attenuate heart rate while exercising on a cycle ergometer. Six experimental (E) subjects received beat-to-beat heart-rate feedback and were asked to slow heart rate while exercising; six control (C) subjects received no feedback. Averaged over 5 days (25 training trials) the exercise heart-rate of the E group was 97.8 bt min-1, whereas the C group averaged 107 bt min-1 (P = 0.03). Systolic blood pressure was unaffected by feedback training. Generally, changes in rate-pressure product reflected changes in heart-rate. Oxygen consumption was lower in the E than in the C group late in training. We conclude that neurally mediated changes associated with exercise in patients with borderline hypertension can be brought under behavioral control through feedback training.

Increase in myocardial oxygen consumption indexes by exercise training at onset of ischemia in patients with coronary artery disease

It has been unclear whether exercise training of patients with coronary artery disease increases the level of myocardial oxygen consumption, as indicated by heart rate and double product of heart rate and systolic blood pressure, at which electrocardiographic evidence of myocardial ischemia develops. To assess this question we evaluated the experience of 10 patients with coronary artery disease who underwent a modest-level exercise training program for 6 months. All of these subjects had achieved a training effect, had developed electrocardiographic evidence of ischemia during initial exercise testing, had not increased the amount of cardiac medication taken, and had not been taking digoxin. After completion of the training period, the mean heart rate at which electrocardiographic evidence of ischemia developed increased from 107 +/- 19 to 119 +/- 23 beats/min (p less than .05) and the mean double product increased from 166 +/- 18 to 209 +/- 51 X 10(2) mm Hg X beats/min (p less than .05). Eight of the 10 patients demonstrated an increase in heart rate at onset of ischemia (p less than .02), and seven of the eight in whom double product could be assessed manifested an increase in this parameter at onset of ischemia (p less than .05). Thus the rate of myocardial oxygen consumption at which myocardial ischemia develops, as indirectly assessed by heart rate and double product, can be favorably altered by 6 months of moderate-level exercise training.

Feasibility and benefits of exercise training in patients on maintenance dialysis

Fourteen of 174 patients receiving maintenance dialysis volunteered to participate in a 12-week exercise conditioning program. Seven patients attended more than 50% (range, 55 to 75%) of the sessions held three times each week. These seven patients achieved a 42% (P less than 0.05) improvement in work capacity as assessed by maximal oxygen consumption during treadmill testing. No changes occurred in psychologic functioning, blood pressure control, hematocrit, or left ventricular ejection fraction. Seven patients attended fewer than half of the sessions (range, 1 to 38%) and did not demonstrate improved exercise capacity. Psychologic testing at entry revealed that those who did not attend regularly had higher scores for hostility, anxiety, and depression as compared to those patients who completed the program. No other clinical variables distinguished those who had good attendance records from those who did not. We conclude that exercise conditioning can improve physical work capacity in patients with chronic renal failure who are receiving maintenance dialysis treatment. Despite this potential benefit, the impact of exercise conditioning programs such as this may be limited because only a small portion of patients on maintenance dialysis are able or willing to participate to an extent sufficient to induce physiological changes.

Work capacity and left ventricular function during rehabilitation after myocardial revascularization surgery

A prospective randomized trial was conducted to evaluate the effects of exercise-based cardiac rehabilitation after myocardial revascularization surgery (MRS) on work capacity (measured in mets) and left ventricular function as determined from ejection fraction (LVEF). Twenty-eight patients undergoing MRS were randomly assigned to experimental (aerobic exercise, n = 19) or control (muscle relaxation and low-level exercise, n = 9) groups. Patients were studied before surgery (T1) and 2 (T2), 8 (T3), and 24 (T4) weeks after surgery with first-pass radionuclide angiography both while they were at rest and during maximal upright cycle ergometric exercise. Subsets of patients were also studied at T2, T3, and T4 at a standard workload of 75 W, and during maximal exercise 1 year after surgery (T5). Work capacity improved in both groups although significantly more so in the experimental group (3.9, 3.8, 6.0, and 7.3 mets and 3.7, 3.7, 4.9, and 5.7 mets at T1, T2, T3, and T4 in the experimental and control groups, respectively). The differences between groups were significant by T3. Peak exercise LVEF increased significantly in both groups from T1 to T2 then decreased at T3 and remained unchanged through T5. Peak exercise LVEF at T3 to T5 remained significantly above that observed at T1. LVEF responses were not related to the exercise program. During a standard workload, heart rate decreased, blood pressure increased, and LVEF did not change in either group. After conclusion of the formal protocol (T4), work capacity and LVEF did not change for either group throughout an additional 6 months (T5).(ABSTRACT TRUNCATED AT 250 WORDS)

Nifedipine and the conditioning response

The effect of nifedipine (N) on conditioning was studied in 14 healthy sedentary men, aged 20 to 34 years. Subjects were ranked according to maximal oxygen consumption (VO2 max), paired, and 1 of each pair randomly assigned to take N, 20 mg, or placebo (C) 3 times daily. Exercise conditioning was 5 times/week for 6 weeks at greater than 85% of maximal heart rate for both groups. Adherence to exercise was 81% for the N and 82% for the C group. After training, the N group improved VO2 max from 41.4 +/- 1.4 to 51.6 +/- 2.0 ml/kg/min (p less than 0.05) and exercise time from 22 +/- 1 to 28 +/- 1 minutes (p less than 0.05). Heart rate (HR) at rest and the product of heart rate and systolic blood pressure both decreased (p less than 0.05): 70 +/- 6 to 55 +/- 4 beats/min; 9,300 +/- 900 to 6,800 +/- 700 beats/min X mm Hg. In the C group, VO2 max increased from 43.2 +/- 2.5 to 49.9 +/- 2.5 ml/kg/min (p less than 0.05); exercise duration improved from 24 +/- 2 to 29 +/- 2 minutes (p less than 0.05), and the rate-pressure product at rest decreased from 8,000 +/- 400 to 6,700 +/- 400 (p less than 0.05). Differences between N and C were not significant. Thus, N, unlike propranolol, does not inhibit the response to exercise conditioning.

Influence of a cardiac rehabilitation program on the cardiovascular, psychological, and social functioning of cardiac patients

Twenty-eight male cardiac patients who had either experienced myocardial infarction or undergone coronary bypass surgery were assigned to a treatment condition and participated in a 3-month, exercise-based Cardiac Rehabilitation Program, whereas 20 other cardiac patients were assigned to a routine-care condition and did not participate in the rehabilitation program. Cardiovascular, psychological, and psychosocial functioning were assessed before treatment or routine care was begun, after 3 months of treatment or routine care, and 4 months later. Results indicated that patients in the treatment condition evidenced reliably more efficient cardiovascular functioning (resting heart rate, resting diastolic blood pressure, treadmill exercise performance, exercise heart rate, exercise systolic blood pressure), better understanding of heart disease, better understanding of and reported compliance with treatment recommendations, more positive self-perceptions (health, body concept, self-concept, progress toward goals), and better psychosocial functioning (e.g., decreased employment-related stress, more active use and enjoyment of leisure time, more physical and sexual activity). Chronic patients benefited as much from the treatment as did acute patients, and the beneficial effects for all treated patients were evident not only just after rehabilitation, but also 4 months later. This investigation appears to be the first such test of effects of this type of treatment, and the results have wide generalizability and applicability.

Effect of prolonged intense endurance training on systolic time intervals in patients with coronary artery disease

We studied the effect of exercise training (ET) on systolic time intervals (STI) in 13 patients with coronary artery disease (CAD). All patients trained for at least 10 months. They exercised three times/week at 50% to 70% of maximal oxygen uptake (VO2max) for the initial 3 months and at least four times/week for approximately 50 minutes at 70% to 90% of VO2max thereafter. A significant training effect was documented by an increase in VO2max from 26.0 +/- 4.3 to 37.2 +/- 5.8 ml/kg/min (p less than 0.01), a lower heart rate (HR) at rest, and a lower blood pressure and HR during submaximal work. The indices of total electromechanical systole (QS2I) and left ventricular ejection time (LVETI) did not change. However, pre-ejection period index (PEPI) decreased from 137 +/- 9 msec to 129 +/- 9 msec (p less than 0.01). PEP/LVET decreased from 0.373 +/- 0.028 to 0.342 +/- 0.032 (p less than 0.01). Left ventricular end-diastolic dimension and posterior wall thickness, measured echocardiographically, were increased after training. We conclude that exercise training may improve myocardial performance in some patients with CAD.

Rehabilitation of the MI survivor. Management options to maximize posthospital outcome

Rehabilitation of the survivor of myocardial infarction (MI) involves efforts to restore or retain maximal function physiologically, psychologically, vocationally, and socially. Goals include delaying or preventing complications, preventing or reversing deconditioning, improving the patient's ability to participate in chosen activities and facilitating his or her return to work, improving psychologic adjustment, and reducing risk factors. A comprehensive rehabilitation program can be guided by an understanding of the natural history of MI in survivors and the risks versus benefits of the interventions discussed.

Efficacy of exercise training in patients with coronary artery disease who are taking propranolol

The effects of beta-adrenergic blockade on the efficacy of exercise training in patients with coronary artery disease were assessed in a community-based cardiac rehabilitation program. Twenty-five patients took no beta-adrenergic-blocking agent and 17 patients took a constant dose of propranolol during the 3 month study period. Individual exercise prescriptions consisted of an intensity of 70% of maximal workload monitored by heart rate, performed 20 min each session, three sessions per week. Both groups improved in maximal exercise capacity: from 8.7 +/- 1.9 (mean +/- SD) to 9.7 +/- 2.1 mets (p less than .01) in those not taking propranolol and from 6.6 +/- 1.5 to 7.7 +/- 1.8 mets (p less than .01) in those taking the drug. At a workload of 70% of maximal achieved at pretraining testing, heart rate decreased with training from 123 +/- 19 to 113 +/- 17 beats/min (p less than .01) in those not taking propranolol and from 97 +/- 14 to 92 +/- 12 beats/min (p less than .05) in those taking the drug. At a workload of 85% of pretraining maximum, heart rate similarly was lowered with training from 138 +/- 17 to 126 +/- 17 beats/min (p less than .01) in those not taking a beta-blocker and from 107 +/- 13 to 102 +/- 13 beats/min (p less than .02) in those taking propranolol. Thus patients with coronary disease who take propranolol have the same potential to benefit from physical training as patients who do not take beta-blockers, and exercise does not need to be modified because of the drug.

Exercise conditioning in middle-aged men after 10 days of bed rest

Of 12 healthy men with a mean age 50 +/- 4 years who had been at bed rest for 10 days, six were randomly assigned to perform individually prescribed physical exercise daily for 60 days after bed rest (exercise group) and six simply resumed their customary activities (control group). Exercise group subjects were significantly more active than control subjects during this interval (p less than .05). Two classic training effects observed in the 60 days after bed rest were significantly larger among exercise than among control group subjects; compared with values immediately after bed rest, heart rate at a constant submaximal workload declined by 36 +/- 11 beats/min in the exercise group vs 16 +/- 8 beats/min in the control group and peak oxygen consumption increased by 4.8 +/- 4.2 vs 2.2 +/- 5.0 ml/kg/min (both p less than .05). Despite these differences in the cardiovascular response to exercise, peak oxygen consumption in both groups returned to before-bed rest levels by 30 days after bed rest, and this was accompanied by significant (p less than .05) and similar increases in resting left ventricular end-diastolic and stroke volumes in both groups. Simple resumption of usual physical activities after bed rest was as effective as formal exercise conditioning in restoring functional capacity to before-bed rest levels.

Cardiac rehabilitation following coronary artery bypass surgery

Early expectations of coronary revascularization prolonging life and reducing coronary events have been modified by 15 years' experience to mostly initial palliation of ischemic symptoms. Bypass surgery represents only a single therapeutic aspect for coronary atherosclerosis. Technically successful operations often fail miserably without overall risk factor alteration and functional capacity optimization which progressive exercise initiates during the postoperative period. Regular activity program participation improves physical conditioning, raises the symptom-limited exertional level, lessens post surgical musculoskeletal discomfort, and improves morale. Yet exercise alone without comprehensive secondary prevention and risk factor modification will be no more successful at arresting atherosclerosis than any other single measure. Both operative intervention and vigorous exertion are valuable components of coronary artery disease therapy, but must be part of an all-embracing effort. Whether regular exertion combined with overall risk factor modification will prolong life and reduce future cardiac events or beneficially alter the process of atherogenesis remain areas of avid investigation.

The description and initial evaluation of an intensive live-in program in risk reduction

Drawing upon the epidemiological, clinical, and behavioral studies suggesting the importance and feasibility of multidisciplinary efforts to reduce levels of risk variables for cardiovascular and other chronic diseases, a short-term live-in intervention program was developed. The program includes efforts to reduce smoking, weight, blood lipids, blood pressure, and stress through improving habits of exercise, nutrition, weight management, and stress control delivered to individuals with varying levels of health risk based on measurable biochemical and physiological variables and medical history. Major changes occurred during the 24-day program in 459 individuals enrolled in the program: 68% of smokers ceased, average cholesterol fell from 240 to 200 mg%, ideal body weight fell from 134 to 129% (82 to 79 kg), systolic blood pressure (BP) fell from 131 to 119 mm Hg, diastolic BP fell from 81 to 73 mm Hg. and reported feelings of general well-being increased. Greater changes were observed in the high-risk groups. Follow-up results at 1 year (48% of patients reporting) for those defined as high risk were a net decrease of 22 mg% in cholesterol, 7 mm Hg in systolic BP, 6 mm Hg in diastolic BP, and 6.8% of ideal body weight; 45% of those smoking at admission were still not smoking at 1 year (32% reporting). For those at lower risk there was a general return of risk levels toward baseline values.

Effects of exercise training on aerobic fitness in children after open heart surgery

Graded treadmill tests to maximal exercise were given to 24 children 1 year or more after open-heart surgery and to 26 age- and sex-matched controls, before and after 9 weeks of exercise training to test whether or not they could increase their aerobic fitness levels. The corrected cardiac lesions included tetralogy of Fallot, aortic stenosis, transposition of the great arteries and atrioventricular canal (AVC). Maximal exercise variables measured were heart rate (HR), oxygen consumption (VO2), and workload (stage of exercise and time on treadmill). The results of the pretraining tests indicated that the fitness levels of the 24 patients were significantly less than those of the controls. Of the original groups, 9 controls and 12 patients satisfactorily completed the training (jogging) program. The results of the post-training tests indicated that both the patients and controls significantly improved their fitness levels. Specifically, most subjects improved their maximal workload with little or no increase in maximal HR or VO2. In conclusion, children after open-heart surgery for complex congenital heart disease can further improve their work capacity by a dynamic exercise program. After training, they are able to do more work at a given VO2.

Role of exercise training in secondary prevention of ischemic heart disease

A review of recent studies indicates that: (1) Physiological characteristics, e.g., left ventricular performance and exercise tolerance, are important prognostic determinants; (2) the natural history of acute myocardial infarction includes a significant degree of spontaneous functional improvement during the early recovery phase; (3) short-term programs of physical training are likely to produce significant functional and symptomatic improvement at no cost in terms of excess mortality or morbidity--the mechanisms of improvement are largely peripheral and regulatory; (4) recent scintigraphic studies suggest that prolonged physical training produces improvement in left ventricular function and myocardial perfusion; (5) long-term studies of the effect of physical training on mortality and morbidity have failed to demonstrate conclusively the efficacy of exercise as a single agent, but provide support for the continued use of physical training as a component of multiple interventions.

Effects of exercise training on ventricular function in patients with recent myocardial infarction

We evaluated the effects of 6 months of exercise training (bicycle ergometry, walking and jogging) on exercise performance and ventricular function in patients with recent myocardial infarction. Fifteen patients were selected on the basis of myocardial infarction at least 6 weeks but not more than 6 months before the study and age younger than 65 years. The patients were evaluated by maximal treadmill exercise testing and radionuclide angiography at rest and exercise before and after training. Before exercise training, maximal treadmill exercise time ranged from 1.5 to 11 minutes, ejection fraction at rest from 18% and 67% and end-diastolic volume from 108 to 208 ml. The mean EF was 48 +/- 5% (+/- SD) at rest and did not change at maximal exercise (48.5 +/- 5%). All 11 patients who completed the exercise training program achieved a significant training effect, as defined by a reduction in heart rate at 50% maximal pretraining effort or an increase in maximal treadmill time. The mean ejection fraction and end-diastolic volume and wall motion abnormalities at rest and at comparable pretraining exercise work loads and heart rates were not significantly different after training. Despite a wide range of rest and exercise ventricular function, patients with recent uncomplicated myocardial infarcts significantly increased their exercise performance. Because rest and exercise ventricular function were comparable before and after training, improvement in exercise performance probably resulted from training effects on the peripheral vasculature.

Exercise responses before and after physical conditioning in patients with severely depressed left ventricular function

The ability of patients with severely impaired left ventricle function to perform short-term exercise and to participate in a cardiac rehabilitation program and attain physical training effects was evaluated. Treadmill exercise tests were performed before and after physical conditioning in 10 patients with a prior myocardial infarction and a left ventricular ejection fraction at rest of less than 27 percent (range 13 to 26) determined by radionuclide angiography. All patients participated in a supervised exercise program with a follow-up period of 4 to 37 (mean 12.7) months. Baseline exercise capacity showed marked variability, ranging from 4.5 to 9.4 (mean 7.0 +/- 1.9) METS, and improved to 5.5 to 14 (mean 8.5 +/- 2.9) METS after conditioning (p = 0.05). The oxygen pulse (maximal oxygen uptake/maximal heart rate) before and after conditioning was used to assess a training effect and increased significantly from 12.8 +/- 2.0 to 15.7 +/- 3.2 ml/beta (p less than 0.01). There was no exercise-related morbidity or mortality, although two patients died during the study period. It is concluded that selected patients with severely imparied left ventricular function can safely participate in a conditioning program and achieve cardiovascular training effects.

Effects of 12 months of intense exercise training on ischemic ST-segment depression in patients with coronary artery disease

This study was undertaken to determine whether adaptation to 12 months of intense endurance exercise training could alter the relationship between the product of heart rate and systolic blood pressure (double product) and the extent of ischemic ST-segment depression during exercise in patients with coronary artery disease. True (i.e., not symptom-limited) maximum oxygen uptake capacity increased from 25.5 +/- 4.2 ml/kg/min (mean +/- SD) to 35.3 +/- 4.4 ml/Kg/min with training. The maximum degree of ST-segment depression during exercise averaged 0.20 +/- 0.04 mV before and 0.16 +/- 0.08 mV after training despite a 20% increase in maximum double product. The double product at which ST depression (0.1 mV) first appeared was 22% greater after training. The extent of ST-segment displacement at the same double product was less after training. These findings suggest that training, if sufficiently intense and prolonged, can result in a reduction in myocardial ischemia at the same or a higher double product.

Demonstration of training effect during chronic beta-adrenergic blockade in patients with coronary artery disease

Attenuation of exercise-induced increases in heart rate and cardiac output by chronic beta-adrenergic blockade has been thought to compromise benefit of exercise training in patients with coronary artery disease (CAD). To assess this important issue, 35 CAD patients were evaluated by a 3-month walk-jog-cycle training program: 14 patients received no beta blocker (group 1), 14 received propranolol, 30-80 mg/day (group 2), and seven patients received propranolol, 120-240 mg/day (group 3). The extent of CAD, resting heart rate before training blood pressure and VO2 max were similar (p = NS) in each group. The maximal exercise heart rate (mean +/- SD, 147 +/- 21 beats/min in group 1 vs 120 +/- 10 beats/min in group 2 and 115 +/- 12 beats/min in group 3 (both p less than 0.05 vs group 1). The VO2 max before training was 25 +/- 5.0 ml/kg/min in group 1 vs 23 +/- 3.2 ml/kg/min in group 2 and 26 +/- 2.8 ml/Kg/min in group 3 (all p = NS). Training consisted of three 1-hour periods per week at a heart rate of 70-85% of the maximal pretraining heart rate. In each group, VO2 increased (p less than 0.05) after training: group 1, 27%; group 2, 30%; group 3, 46%. The double product was unchanged after training (p = NS) in each group. These data indicate that substantial training effects may be achieved in CAD patients despite therapeutic doses of beta blockers and a reduced training HR. Thus, there appears to be no indication to reduce beta blockers in CAD patients engaged in cardiac rehabilitation.

Effect of exercise training on the untrained limb exercise performance of men with angina pectoris

This study examined the exercise capacity of trained and untrained limbs in men with angina pectoris before and after 8 weeks of arm ( n = 4) or leg (n = 7) physical training or a control (n = 4) period. Time to angina (mean +/- standard deviation) increased 3.6 +/- 2.7 minutes (p less than 0.01) during trained limb and 1.6 +/- 1.2 minutes (p less than 0.01) during untrained limb exercise. Myocardial oxygen demand at angina estimated by the product of heart rate and systolic blood pressure did not change with training. At a constant subanginal work load, rate-pressure product x 10(-2) was reduced by 35 +/- 22 (p less than 0.001) during trained limb and by 18 +/- 27 (p less than 0.05) during untrained limb exercise. The decrease in rate-pressure product with both trained and untrained limbs was greatest in subjects with the highest rate-pressure product at angina before training. Control subjects showed no change in any exercise measurement. Exercise training increases the exercise capacity of untrained limbs in patients with angina pectoris by a generalized training effect not dependent on adaptations in trained skeletal muscle. The improvement for both trained and untrained limbs results from a reduced rate-pressure product at subanginal work loads rather than from an increase in myocardial oxygen delivery. Subjects with the highest pretraining coronary arterial oxygen supply at the onset of angina benefit most from physical training.

Respiratory alkalemia during exercise reduces angina threshold

The effect of hyperventilation-induced alkalemia on angina threshold was evaluated in nine subjects who had a consistent pattern of chest pain and ST segment depression during exercise. For this study, the subjects performed graded bicycle exercise to angina during normal breathing and during hyperventilation. The maximum workload achieved was not significantly different between normal breathing and hyperventilation exercise. However, in five subjects who had arterial alkalemia during hyperventilation exercise (mean pH = 7.52), the heart rate X blood pressure product (HR X BP) at angina was 224 X 10(2) compared with 240 X 10(2) during normal breathing exercise (P less than 0.05). Four subjects appeared to hyperventilate, but were not alkalemic (mean pH = 7.40). Their HR X BP at angina was not significantly different between the two exercise periods (288 X 10(2) vs 284 X 10(2). In conclusion, the threshold for angina during exercise fell in the five patients in whom hyperventilation caused alkalemia. This finding suggests that the alkalemia interfered with myocardial oxygen supply.

Physical conditioning augments the fibrinolytic response to venous occlusion in healthy adults

The effects of a 10-week physical-conditioning program on fibrinolytic activity at rest and after stimulation by venous occlusion were studied in 69 healthy adults 25 to 69 years old. Physical conditioning was documented by treadmill performance, and fibrinolysis was measured with a newly developed radioenzymatic assay. Whereas fibrinolysis declined at rest from 16.2 +/- 1.3 to 11.4 +/- 0.8 units (mean +/- S.E.M.) (P = 0.0017), the increment in fibrinolysis produced by venous occlusion was increased from 21.7 +/- 2.9 to 33.8 +/- 4.7 units (P = 0.0037). This augmentation was most marked in women, persons with low initial levels of stimulated fibrinolysis, and persons with low initial physical fitness. We conclude that physical conditioning can enhance the augmentation of fibrinolytic activity that occurs in response to venous occlusion. Enhanced fibrinolysis in response to thrombotic stimuli could be an important mechanism in the beneficial effect of habitual physical activity on the risk of cardiovascular disease.

The role of behavioral conditioning in the cardiovascular adjustment to exercise

The purpose of this study was to determine if normal subjects could be trained to attenuate their cardiovascular responses while exercising on a bicycle ergometer. Ten young, untrained subjects exercised on a bicycle ergometer for five sessions. Half of the group was asked to slow their heart rate while exercising with heart rate feedback during exercise. Their average heart rate increase was 20% less than that of the control subjects, who exercised without feedback. The control subjects subsequently also received feedback during exercise and they were able to attenuate their heart rate responses comparably. Systolic blood pressure was not affected by feedback training. Changes in rate-pressure product paralleled changes in heart rate. These data show that autonomically mediated adjustments to exercise can be brought under experimental control through the use of appropriate behavioral techniques.

Effects of physical training on myocardial ischaemia in patients with coronary artery disease

The effects of a simple physical training programme were investigated in a prospective and randomised trial in patients with stable angina pectoris using a modified exercise test. Twenty-four patients with ischaemic heart disease and an ischaemic response to conventional exercise electrocardiography were randomised into two groups: 12 patients took part in a training programme and 12 patients were allocated to a control group (no training). Exercise testing was performed sequentially at entry to the study and six months afterwards. At both studies we determined the heart rate at the same level of ischaemic ST segment depression (HR/ST threshold), the duration of the test, and relation of heart rate to the exercise load. The HR/ST threshold increased only in patients who underwent the exercise programme, suggesting indirectly that training resulted in the ability to do more work and attain a higher degree of myocardial oxygen consumption at the same level of myocardial ischaemia. In addition, training led to an increase in the duration of the test and to a reduction in heart rate at any level of submaximal exercise load. It is concluded that physical training in anginal patients results in an enhancement of myocardial oxygen availability.

Left ventricular pump function before and after aortocoronary bypass surgery

Ten patients with severe effort angina and with left ventricular dysfunction during exercise before operation underwent haemodynamic and angiographic studies in average 20 months after coronary artery bypass surgery. Five patients (50%) were completely asymptomatic after operation(group I). The other five (group II) were still limited physically because of anginal pain, although two were much improved. Pre-operatively there was no significant difference in the severity of the disease, as judged from case histories, work tests and haemodynamic and angiographic findings between the two groups. The working capacity of the patients in group II was not increased significantly post-operatively. Their coronary arteriograms revealed unsatisfactory surgical results. In two patients, one significantly stenosed vessel was not bypassed because of poor run-off. In the other three patients, one graft was closed. Left ventricular function curves showed no significant improvement of left ventricular pump function. In group I, working capacity increased significantly, all stenoses of major coronary vessels were bypassed and all grafts were patent. Left ventricular function showed an almost normal response during exercise. These findings suggest that left ventricular dysfunction due to ischaemia can be significantly improved by coronary bypass and that there is a good correlation between clinical, haemodynamic and angiographic findings.

Clinical guidelines for exercise training

Exercise training may be useful for a variety of patients with and without established cardiovascular disease. The degree to which a patient participates in a prescribed exercise program depends strongly on initial motivation. The primary care physician can provide appropriate reinforcement with careful explanation of the effects of exercise on cardiovascular and metabolic function. Exercise programs may be combined effectively with other life-style adjustments, including weight loss, blood pressure control, and discontinuation of smoking. As a single intervention factor, exercise cannot prevent the evolution of cardiovascular disease in multiple-risk patients. Exercise is best used in combination with a program of comprehensive cardiovascular risk factor modification.

Lidoflazine and physical training in the treatment of stable angina pectoris

An additive effect in the treatment of angina pectoris by combining lidoflazine and physical training was postulated. Twenty-four patients were randomly divided into placebo and drug groups and subsequently underwent a 6-month physical training program. The drug group had a significantly greater reduction in submaximal heart rate than the placebo group. Similar improvements in symptom-limited exercise capacity were observed in both groups. Resting and maximal exercise coronary sinus blood flow and left ventricular oxygen consumption were not significantly changed with training in either group. Physical training and lidoflazine appear to influence exercise tolerance in the same manner.

Research related to rehabilitation

Progress in cardiac rehabilitation demands that rehabilitation efforts for the patient after myocardial infarction or aortocoronary bypass surgery be integrated into a comprehensive program of acute and ambulatory cardiac care. To permit a more rapid return of coronary patients to a normal or near-normal lifestyle and role in society, further delineation of the scientific bases for all components of rehabilitation programming and identification of both barriers to and facilitators of rehabilitation are necessary to improve rehabilitative services.

Exercise can promote coronary collateral development without improving perfusion of ischemic myocardium

We studied the effect of exercise training on the coronary collaterals that developed in response to gradual coronary occlusion in dogs. After their proximal left circumflex coronary artery occlusion, 33 dogs were randomly assigned to exercise or sedentary groups. Coronary collateral function was evaluted 5 weeks or 8 weeks later. The exercised dogs developed better epicardial collateral connections to the occluded left circumflex as judged by higher retrograde blood flow from the distal left circumflex and lower pressure drop across the collaterals. No difference in collaterals was apparent angiographically. Microsphere data indicated that exercise dogs were not better protected against tachycardia provoked subendocardial ischenia in the myocardium supplied by the collaterals.

Evaluation of the beta-blocking drug acebutolol in angina pectoris

The effects of the beta-adernergic blocking drug acebutolol were studied in 23 patients with angina pectoris and angiographically documented coronary artery disease. Patients were evaluated clinically, by graded treadmill testing and by 24-hour Holter monitoring in the control state, after 2 weeks treatment with placebo, and after 2 weeks treatment with 600 mg. and then 1,200 mg. of acebutolol. Acebutolol (in a daily dose of 600 mg.) was an effective antianginal drug: the number of clinical attacks of angina pectoris (p less than 0.001) and the consumption of sublingual nitrate decreased (p less than 0.01), there was a significant increase in the treadmill effort tolerance as measured by the time to appearance of ischemic ECG changes (p less than 0.001) and the total work performed (p less than 0.001), and there was also a significant decrease in ischemic ST segment depression on 24-hour Holter monitoring. Treatment with 1,200 mg. acebutolol was associated with a further decrease in heart rate and a further improvement in effort tolerance on treadmill testing (p less than 0.05). On the large dose of the drug, however, there was no further clinical improvement, and no further improvement on 24-hour ECG monitoring; several patients complained of weakness and fatigue. Graded treadmill testing was an excellent objective method for assessing physical effort tolerance and its improvement after treatment with the beta-blocking drug. Twenty-four-hour Holter monitoring was a useful and complementary test, especially in patients who stopped exercising on the treadmill because of fatigue or weakness, and especially for assessing the efficacy of beta-blockade in controlling emotionally induced tachycardia and ischemia in the patient's own daily environment.

Exercise and human collateralization: an angiographic and scintigraphic assessment

The effect of exercise on the development of intercoronary collaterals and on left ventricular function is controversial. Twenty male patients (mean age 48 years, range 36-54 years) who had suffered an acute myocardial infarction were randomly allocated to an exercise group (10 patients) and a control group (10 patients). Both groups underwent coronary angiography, left ventricular function studies and myocardial perfusion studies with labeled microspheres, before and after the 7-month experimental period. Both groups had similar extent of disease as measured angiographically and both had mild progression of disease. Neither group showed changes in extent of callateralization, myocardial perfusion or left ventricular function. The exercise group had a significant increase in anginal threshold and a significant (p less than 0.01) decrease in heart rate at a given work load. Exercise, therefore, does not appear to affect progression of disease, myocardial perfusion, extent of collateralization, or left ventricular function in patients with coronary artery disease.

Instrumental cardiovascular conditioning: a review

This paper reviews experiments, hypotheses, and current controversies about instrumental cardiovascular conditioning. Demonstrations of such conditioning in curarized animals challenged a differentiation between instrumental and classical learning on the basis of their respective effector systems but did not prove direct operant learning by the autonomic nervous system. In humans, ethical prohibition of curarization and lack of adequate controls for respiration and muscle tension have resulted in incomplete understanding of the roles of voluntary, somatic mediators. Despite a variety of potential clinical applications of biofeedback, the available literature lacks studies of its efficacy compared to more standard modes of therapy. The physiological mechanisms and central neural pathways involved in instrumental cardiovascular conditioning remain almost totally unknown.