Exercise physiology in cardiovascular diseases

Exercise testing protocols and training regimens are well established for patients recovering from myocardial infarction or coronary artery bypass surgery. However, exercise rehabilitation programs for patients with peripheral arterial disease or left ventricular dysfunction with congestive heart failure have not been well developed. Several recent reports have established reproducible exercise testing protocols with objective measures of performance for patients with peripheral arterial disease and congestive heart failure. Using these testing methods to define changes in exercise capacity, exercise training programs have been shown to result in a significant increase in exercise performance and community-based quality of life. The mechanism of improvement appears to involve peripheral adaptations in skeletal muscle metabolism rather than increases in cardiac output or peripheral blood flow.     

Cardiovascular exercise and wellness. Exercise training for cardiac rehabilitation patients: meeting the challenges of the millennium

Exercise training for cardiac rehabilitation has evolved over the past decades in response to a growing knowledge base in exercise physiology, an expanding understanding to the knowledge base of coronary disease, and a change in the patients presenting for cardiac rehabilitation. The patient population has changed from a post myocardial infarction patient group, to patients who have had coronary artery revascularization (coronary artery bypass surgery or percutaneous transluminal coronary angioplasty) with the implantation of intraarterial stents. Program goals have evolved from enhancing endurance fitness in deconditioned patients to initiating the long-term adoption of an active exercising lifestyle with the use of strength training to complement endurance training. An increased understanding of behavioral issues in the adoption of an active lifestyle will influence the evolution of cardiac rehabilitation exercise training. During the next several years, it is anticipated that the patient population will change to include patients with significant left ventricular systolic dysfunction and congestive heart failure. The exercise training programs will then further evolve to reflect the successful exercise training formats utilized in the multicenter trials of exercise training for patients with congestive heart failure. (c) 2000 by CHF, Inc.     

Exercise training restores aerobic capacity and energy transfer systems in heart failure treated with losartan

OBJECTIVE: Clinical and experimental studies demonstrate that exercise training improves aerobic capacity and cardiac function in heart failure, even in patients on optimal treatment with angiotensin inhibitors and beta-blockers, but the cellular mechanisms are incompletely understood. Since myocardial dysfunction is frequently associated with impaired energy status, the aim of this study was to assess the effects of exercise training and losartan on myocardial systems for energy production and transfer in heart failure. METHODS: Maximal oxygen uptake, cardiac function and energy metabolism were assessed in heart failure after a myocardial infarction induced by coronary artery ligation in female Sprague-Dawley rats. Losartan was initiated one week after infarction and exercise training after four weeks, either as single interventions or combined. Animals were sacrificed 12 weeks after surgery. RESULTS: Heart failure, confirmed by left ventricular diastolic pressure >15 mmHg and by >20 mmHg drop in peak systolic pressure, was associated with 40% lower aerobic capacity and significant reductions in enzymes involved in energy metabolism. Combined treatment yielded best improvement of aerobic capacity and ventricular pressure characteristics. Exercise training completely restored aerobic capacity and partly or fully restored creatine and adenylate kinases, whereas losartan alone further reduced these enzymes. In contrast, losartan reduced left ventricle diastolic pressure, whereas exercise training had a neutral effect. CONCLUSION: Exercise training markedly improves aerobic capacity and cardiac function after myocardial infarction, either alone or in combination with angiotensin inhibition. The two interventions appear to act by complementary mechanisms; whereas exercise training restores cardiac energy metabolism, mainly at the level of energy transfer, losartan unloads the heart by lowering filling pressure and afterload.     

Patients with large myocardial infarction gain a greater improvement in exercise capacity after exercise training than those with small to medium infarction

BACKGROUND: It remains unclear whether patients with large-size myocardial infarction (MI) achieve the same benefit from exercise training as do those with small- to medium-size MI. HYPOTHESIS: This study was designed to determine the magnitude and mechanisms underlying improvement in exercise capacity in patients with large-size MI after cardiac rehabilitation. METHODS: In all, 296 patients who participated in a cardiac rehabilitation program after acute MI were divided into two groups according to the peak serum creatine phosphokinase (CPK) level: the group with large infarction (Group 1) (> or = 5000 U/l peak CPK, 64 patients) and the group with less extensive infarction (Group 2) (< 5000 U/I, 232 patients). Exercise capacity was assessed before and after a 3-month cardiac rehabilitation program that included exercise training. RESULTS: Before exercise training, both the peak work rate (p < 0.05) and peak oxygen uptake (VO2) (p < 0.01) were significantly lower in Group 1 than in Group 2. After exercise training, the changes in peak work rate and peak VO2 were significantly greater in Group 1 than in Group 2 (both p < 0.01). The infarction size measured by the peak CPK level correlated significantly with both the baseline exercise capacity and its improvement after exercise training, although these correlations were insignificant in a multivariate analysis. In the multivariate analysis, the improvement in exercise capacity is determined by age and baseline exercise capacity, which is determined by the duration of inactivity, minute ventilation (VE)/VCO2 slope and left ventricular end-diastolic pressure. CONCLUSIONS: Compared with patients with small- to medium-size myocardial infarction, patients with large infarction gain a greater improvement in exercise capacity after exercise training due to reversal of physical deconditioning and improvement in congestive heart failure.     

Prognosis after initial myocardial infarction: the Framingham study.

During 20 years of follow-up of 5,127 men and women initially free of coronary heart disease in the Framingham cohort, 193 men and 53 women had one or more recognized, symptomatic myocardial infarctions. An additional 45 men and 28 women had unrecognized myocardial infarctions. Subsequent mortality and morbidity including angina, reinfarction, congestive failure and sudden death were ascertained. One in five men who had a first myocardial infarction died within 1 year, a mortality rate 14 times that of those free of coronary heart disease. In men who survived the 1st year, a recognized myocardial infarction increased risk of death over the next 5 years to 23 percent, four times that of the general population. The next 5 years carried a 25 percent mortality (three times that of the general population). The prognosis was distinctly worse in women than in men chiefly because of a higher (45 percent) early mortality rate in women. Patients with recognized and unrecognized myocardial infarctions had similar survival rates after 3 years. A second myocardial infarction occurred in 13 percent of the men and in 40 percent of the women within 5 years of the first infarction. Thus, women were more prone to death and reinfarction than men. Congestive heart failure occurred as commonly as reinfarction, affliction 14 percent of the men within 5 years of the initial infarction. Once congestive failure ensued, half of the affected patients were dead within 5 years. Angina developed in one third of the patients within 5 years of their first infarction.     

Myocardial infarction in young patients: an analysis by age subsets

We examined, in age subsets, 2643 patients with acute myocardial infarction. Clinical features and 1 year morbidity and mortality were compared in 203 young patients (less than 45 years), 1671 patients 46 to 70 years old, and 769 elderly patients (greater than 70 years). Ninety-two percent of young patients were men, and a family history of premature coronary artery disease was more common in young patients (41% compared with 28% of middle-aged and 12% of elderly patients). More young patients were currently smoking cigarettes (82% compared with 56% of middle-aged and 24% of elderly patients), and only 8% of young patients had never smoked. Previous myocardial infarction and history of angina pectoris or congestive heart failure were less common (p less than .001) in the young patients than in middle-aged and elderly patients. In-hospital mortality was only 2.5% for young patients, compared with 9.0% in middle-aged and 21.4% in elderly patients (both p less than .001). Postdischarge 1 year mortality was also strikingly low in young patients, at 2.6% compared with 10.3% in middle-aged and 24.4% in elderly patients. The incidence of reinfarction during the 1 year of follow-up was similar in all subsets. The statistical significance of 65 variables as predictors of 1 year mortality and reinfarction was tested and the following found to be significant (p less than .05): hospital discharge on antiarrhythmic drugs, digoxin, or diuretics; history of previous myocardial infarction or congestive heart failure; chest x-ray findings of heart failure; low ejection fraction; and atrial fibrillation. Thus, young patients entering the hospital have an excellent 1 year prognosis, but those with prior infarction in whom there are selected abnormal findings at hospital discharge comprise a subgroup that may benefit from early aggressive management.     

Anti-angina therapy of coronary heart disease. Mono- or combination treatment]

Applying a metaanalysis, it was examined whether a combination of drugs is superior to monotherapy in the treatment of angina pectoris. The three classical groups of anti-anginal drugs, nitrates, calcium channel blockers and beta-receptor blockers were investigated. For data analysis, patients were divided in those suffering from "angina pectoris" and those suffering from "angina pectoris despite monotherapy." In patients with the inclusion criterium "angina pectoris" combination of drugs is not superior to monotherapy. This applies to the evaluation criteria "improvement of symptoms" and "reduction of ischemia". In patients with the inclusion criterium "angina pectoris despite monotherapy" however, there is a clear superiority of drug combination as compared to monotherapy. Again this applies to the evaluation criteria "improvement of symptoms" and "reduction in myocardial ischemia". With respect to antianginal efficacy all three possible combinations appear to be similar. If the evaluation criterium is "improvement of prognosis" no data are available with regard to drug combination. Furthermore no data are available on the prognostic effect of an anti-anginal therapy in patients with stable angina pectoris. A significant improvement of prognosis could be demonstrated for beta-receptor blocking agents without ISA in unstable angina, acute myocardial infarction, and in the postinfarction period. The effect of calcium channel blockers on prognosis depends on the substance class applied and on the presence or absence of signs of congestive heart failure. Monotherapy with nifedipine in instable angina and acute myocardial infarction fails to improve prognosis, and there even may be a tendency to adverse effects. In the absence of signs of congestive heart failure verapamil has been demonstrated to improve prognosis in the post infarction period. Likewise, improvement of prognosis by the administration of diltiazem in acute myocardial infarction only could be demonstrated in patients without signs of heart failure. In contrast, in patients with signs of congestive heart failure diltiazem increased the rate of reinfarction and mortality. For nitrates only in acute myocardial infarction a trend towards improved prognosis has been shown. Especially for nitrates the data on prognosis in coronary heart disease available so far are not convincing.     

Myocardial infarction in the diabetic patient

It has long been thought that the symptomatology and prognosis of coronary events in patients with diabetes may differ from those in nondiabetic persons. A review of recent data demonstrates a higher mortality during the acute phase of myocardial infarction for diabetic patients than for their nondiabetic counterparts, possibly related to a higher incidence of congestive heart failure and cardiogenic shock. The clinical course of diabetic patients with infarction and the role of insulin in myocardial adaptation to ischemia are both reviewed. Diabetic patients surviving the acute phase of myocardial infarction have a lower survival in follow-up than nondiabetic survivors, although some improvement in survival has been noted following beta-adrenergic-blocker therapy.     

Prognostic value of exercise tests in male veterans with chronic coronary artery disease

PURPOSE: The authors evaluate the prognostic value of treadmill testing in a large consecutive series of patients with chronic coronary artery disease. Exercise testing is widely performed, but analyses of the prognostic value of test results have largely concentrated on patients referred for the diagnosis of coronary artery disease, patients after an acute coronary event or procedure, or patients with congestive heart failure. METHODS: All patients referred for evaluation at two university-affiliated Veterans Affairs Medical Centers who underwent exercise treadmill tests for clinical indications between 1987 and 2000 were determined to be dead or alive using the Social Security Death Index after a mean 5.8-year follow-up. Patients without established heart disease and those with congestive heart failure were excluded, leaving the target population of those with a history myocardial infarction or coronary intervention. Clinical and exercise test variables were collected prospectively according to standard definitions; testing and data management were performed in a standardized fashion using a computer-assisted protocol. All-cause mortality was used as the endpoint for follow-up. Standard survival analysis was performed including Kaplan Meier curves and the Cox Hazard Model. RESULTS: Of the 1,473 patients with coronary artery disease who had exercise testing, 273 (19%) patients had a revascularization procedure (Revascularization group); 813 (55%) had a history of myocardial infarction, diagnostic Q waves (MI group), or both; and 387 (26%) had a history of myocardial infarction or Q wave and revascularization (Combined group). Mean age of the patients was 61.8 +/- 9 years. A total of 401 deaths occurred during a mean follow-up of 5.8 years with an annual mortality rate of 4.5%. Only two variables, age and maximal exercise capacity, were independently and statistically associated with time to death in all three groups and were the strongest predictors of all cause mortality. CONCLUSION: A simple score based on METs, age, and history of myocardial infarction or diagnostic Q waves can stratify prognosis in patients with chronic coronary artery disease. The score enabled the identification of a group at low risk (32% of the cohort) with an annual mortality rate of 2%, a group at intermediate risk (42% of the cohort) with an annual mortality rate of about 4%, and a group at high risk (26% of the cohort) with an average annual mortality rate of approximately 7%.     

Exercise training and endothelial dysfunction in coronary artery disease and chronic heart failure. From molecular biology to clinical benefits

Endothelial dysfunction (ED) has been documented in patients with both coronary artery disease (CAD) and chronic heart failure (CHF)-being responsible for exercise-induced myocardial ischemia in the former and increased afterload in the latter. In the last two decades exercise training has assumed a major role in both cardiovascular disorders. In CAD exercise training has established positive effects on myocardial perfusion. Recently, exercise training has been shown to attenuate paradoxical vasoconstriction in CAD. The improved ED after training explains the improvement of myocardial perfusion in the absence of changes in baseline coronary artery diameter. Since ED has been identified as a predictor of coronary events exercise may contribute to long-term reductions of cardiovascular mortality. In CHF the increased peripheral vascular resistance - especially during exercise - is more important. ED contributes to the peripheral vasoconstriction. Training programs have shown to improve ED in CHF. A long-term study of hemodynamic effects of training in CHF revealed a significant reduction of total peripheral resistance (TPR) that after 6 months with a concomitant increase in stroke volume. In a subgroup analysis a significant correlation between changes in TPR and changes in peripheral ED was observed. Cell culture and animal experiments suggest that shear stress increases the endothelial L-arginine uptake, enhances NO synthase activity and expression, and upregulates the production of extracellular superoxide dismutase, which prevents premature NO breakdown. All these molecular effects converge on a reduction of myocardial ischemic events in CAD and a decrease of afterload in CHF.     

Effect of age on long-term prognosis of patients with myocardial infarction

We studied 181 patients aged under 65 years and 129 patients over 65 with acute myocardial infarction. There were no major differences in the prevalence of coronary risk factors, angina or previous myocardial infarction. A larger percentage of elderly patients had congestive heart failure (51.4% vs 32.6%, P less than 0.001) and complete heart block (17.1% vs 7.2%, P less than 0.01) during the acute phase. In-hospital mortality was significantly higher in the elderly patients (34% vs 16%, P less than 0.01). Late mortality rates correlated in both groups with the Killip class at the time of infarction and with the occurrence of reinfarction. In the elderly group, it was also associated with complete heart block during the acute phase. Five-year survival was 80% in the older and 72% in the younger patients (P = 0.1). Age did not affect survival of Killip class I patients (85% vs 86%, P = 0.83), but life expectancy was significantly reduced in elderly patients in Killip class greater than II (39% vs 60%, P less than 0.05). In conclusion, elderly patients cannot be considered a homogeneous group of high-risk patients. Clinical variables at the time of infarction can identify low- and high-risk subsets among them. Age constitutes an independent prognostic factor for late mortality when any degree of heart failure is present.     

Exercise Training as a Therapy for Chronic Heart Failure: Can Older People Benefit?

Despite recent advances in pharmacological therapy, chronic heart failure remains a major cause of morbidity and mortality in older people. Studies of exercise training in younger, carefully selected patients with heart failure have shown improvements in symptoms and exercise capacity and in many pathophysiological aspects of heart failure, including skeletal myopathy, ergoreceptor function, heart rate variability, endothelial function, and cytokine expression. Data on mortality and hospitalization are lacking, and effects on everyday activity, depression, and quality of life are unclear. Exercise therapy for patients with heart failure appears to be safe and has the potential to improve function and quality of life in older people with heart failure. To realize these potential benefits, exercise programs that are suitable for older, frail people need to be established and tested in an older, frail, unselected population with comorbidities.     

老年再发与初发心肌梗死患者的临床病理对照分析

目的探讨老年再发心肌梗死与初发心肌梗死患者临床病理的差异。方法对107例尸体解剖证实的老年人心肌梗死分为再发梗死与初发梗死两组(再梗组56例,初发组51例),并进行临床病理对照分析。结果再梗组平均年龄(78.7±9.8)岁大于初发组(72.2±10.4)岁(P=0.0012)。再梗组糖尿病患者30例(53.6%)明显多于初发组12例(23.5%,P=0.0015)。再梗组冠状动脉明显狭窄130支(60.7%,平均2.32支/例),明显多于初发组的84支(39.3%,平均1.65支/例,P=0.0047)。再梗组双支以上明显狭窄共40例(71.4%),多于初发组的27例(52.9%,P=0.031)。再梗组两个部位以上梗死41例(73.2%)多于初发组的27例(52.9%,P=0.0295)。再梗组室壁瘤21例(37.5%)多于初发组的10例(19.6%,P=0.0416)。心脏破裂再梗组7例(12.5%)少于初发组的15例(29.4%,P=0.0306)。再梗组死亡原因以心力衰竭和心律失常多见,为33例(58.9%),而初发组则为20例(39.2%,P=0.0417)。结论老年患者再发心肌梗死的特点可能为患病年龄更大,并发糖尿病者多,冠状动脉多支严重病变常见,心肌梗死范围大,且易形成室壁瘤。     

Exercise training improves activities of daily living in elderly patients with congestive heart failure

Exercise training which is one of the multidisciplinary interventions for elderly patients with congestive heart failure, plays an important role for improving the quality of life and reducing the re-admission rate of these patients. We assessed the validity of exercise training for the improvement of patient's skeletal muscle functions and activities of daily living along with monitoring cardiac functions. Exercise training programs were performed in 12 patients with congestive heart failure (New York Heart Association class III or IV), including 5 with valvular disease, 4 with dilated cardiomyopathy and 3 with ischemic cardiomyopathy (mean 79 +/- 9 years). All patients were admitted because of exacerbation of congestive heart failure and were treated conventionally. The exercise training program was started after stabilization of their cardiac condition. The medication was not changed during the training period. After exercise training programs, the cardio-thoracic ratio decreased from 63.8 +/- 7.9% to 60.1 +/- 6.9% (p < 0.01), ejection fraction on echocardiography increased from 47.4 +/- 18.2% to 56.0 +/- 17.5% (p < 0.01), and brain natriuretic peptide decreased from 404.8 +/- 267.5 pg/ml to 313.6 +/- 239.5 pg/ml (p < 0.05). The quadriceps muscle power increased from 0.77 +/- 0.36 Nm/kg to 0.97 +/- 0.41 Nm/kg (p < 0.01). The maximum walking distance on flat surface increased from 149 +/- 164 m to 456 +/- 394 m (p < 0.05). In most patients, the activities of daily living, especially mobility, improved. Appropriate exercise training for the elderly patients with congestive heart failure improves activities of daily living and also reduces the amount of required care by the patients.     

Epoprostenol sodium (prostacyclin) infusion in acute myocardial infarction.

Epoprostenol (prostacyclin) is a potent inhibitor of platelet aggregation and causes relaxation of vascular smooth muscle. These effects may be beneficial in patients with acute myocardial infarction. The effect of epoprostenol infusion in patients with acute myocardial infarction was evaluated in a randomised double blind study of 45 patients with evidence of myocardial infarction of less than 16 hours' duration. The patients were given a 72 hour infusion of epoprostenol (23) or placebo (22). The maximum dose was 5 ng/kg/min. The mean time to treatment was 8.3 hours (range 3.8-15.9 hours). The mean dose was 4.9 ng/kg/min. The patients were followed until day 30. No significant differences were found between the groups in mortality, development of congestive heart failure, cardiogenic shock, arrhythmias, recurrent chest pain, reinfarction, peak creatine kinase concentration, or the time taken to attain peak creatine kinase concentration. No significant difference in baseline ejection fraction was noted between groups, and no significant change in ejection fraction occurred within each group or between groups. The only significant side effect was the development of facial flushing in the epoprostenol group. In this pilot study epoprostenol was well tolerated by patients with acute myocardial infarction. No benefit from epoprostenol could be demonstrated at the dose range used when the drug was administered within 16 hours of the onset of symptoms.     

Dx and Tx of the elderly patient with atherosclerotic coronary heart disease

Complications of MI occur in patients of all ages, but are more common in the elderly. Prevalent are atrial and ventricular dysrhythmias, papillary muscle dysfunction, pericarditis, congestive heart failure, atrioventricular block, cardiogenic shock, and myocardial rupture. Improved surgical techniques and methods of myocardial protection have reduced the perioperative mortality of coronary artery bypass surgery in older persons to an acceptable level.     

运动对心脏的保护作用及其机制的研究进展

运动训练有益心脏健康,可以改善心血管疾病患者的运动能力和生活质量,降低其致死率和致残率。尽管运动的益处显而易见,但是运动训练对于心脏疾病的保护机制尚不明确。本文重点综述了运动保护心脏的主要机制,以及运动对于心肌梗死、缺血再灌注损伤、病理性心肌肥厚、心脏衰老等心脏疾病的保护作用及最新研究进展,以期从"运动"这一独特视角,为心脏疾病的防治提供新思路和新策略。     

Prognostic value of low-level exercise testing in patients with myocardial infarction

The prognostic value of low-level exercise testing (EXT) before hospital discharge was assessed in 111 patients with uncomplicated acute myocardial infarction (AMI). Of 111 patients, 94 were followed for 1 year after AMI to find that 22 carried a poor prognosis: reduction in duration of EXT (6 patients), postinfarction angina (2 patients), congestive heart failure (3 patients), coronary bypass graft surgery (7 patients) and reinfarction (4 patients). The prognosis was poor in 3.7% of 54 patients who tolerated exercise for 721 seconds or longer (4.2 METs) and 50% of 40 patients tolerating it no longer than 720 sec (p less than 0.0001). Of 22 patients who turned out to be carriers of a poor prognosis, 12 (54.5%) had an ST segment change during EXT, but 10 of the 12 patients were asymptomatic. Our results suggest that reduction in duration of exercise and asymptomatic ST segment changes during EXT provide important clues to establishing the short-term prognosis of AMI.     

Secondary prevention after myocardial infarction: Subgroup analysis of patients at risk in the norwegian timolol multicenter study

Timolol treatment after myocardial infarction is generally related to a significant reduction in both morality and reinfarction compared with placebo. Retrospective analyses of the timolol study are performed on subgroups of patients with a high placebo mortality. The present study shows that these patients are target groups for secondary prevention, as they benefit most from timolol treatment after myocardial infarction. In patients 65-75 years of age, the number of cardiac deaths and reinfarctions prevented by timolol treatment is twice as high as that of patients below 65 years of age. Timolol treatment is well tolerated in the older age group and the contraindications for timolol treatment are independent of age up to 75 years. The reduction in mortality and reinfarction is independent of heart size at baseline. However, in patients with cardiomegaly and compensated heart failure on treatment with digitalis and diuretics, timolol treatment may be of special importance because of the very high incidence of cardiac death in this group of patients. In patients with compensated heart failure on treatment with digitalis and diuretics, timolol treatment does not precipitate heart failure. Patients with stable diabetes mellitus basically behave like nondiabetic patients regarding inclusion rate, side effects, and timolol-related reduction in mortality and reinfarction. Decisions concerning secondary prevention with timolol should be independent of preinfarction and postinfarction angina. In conclusion, 70-80% of all the patients below 75 years of age surviving myocardial infarction, without contraindication to betablocker treatment, can be treated with timolol 10 mg twice daily to reduce mortality and reinfarction. In contrast to previous routines, secondary prevention with beta blockers should be especially directed to high-risk patients.     

Exercise training improves diastolic perfusion time in patients with coronary artery disease

Exercise training elicits an improvement in work capacity and in left-ventricular function in patients with coronary artery disease. An improvement in myocardial oxygen supply accounts for these effects. The aim of this study was to test the hypothesis that exercise training could favorably influence diastolic perfusion time, a major determinant of subendocardial perfusion. Twenty-two male patients with coronary artery disease were randomized to a training or control group. At the study entry and after one year, all patients underwent an exercise stress test. After one year, rest heart rate was lower and diastolic perfusion time was higher in the training group but not in the control group. At peak of exercise, diastolic perfusion time increased and ST-segment depression decreased significantly in the training group but not in the control group. A significant relation was found between the R-R interval and the diastolic perfusion time either before or after training, with a difference in the intercepts of two regressions. Training shifted updown-line regression, effecting a higher value of diastolic perfusion time for a given value of heart rate. Thus, training increases diastolic perfusion time, independently from the effect on heart rate. This mechanism may contribute to the improvement of myocardial perfusion.