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PubMedDate not supplied

Pulmonary rehabilitation in patients with chronic obstructive pulmonary disease.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is a major cause of morbidity and mortality in India. Drug treatment alone does not optimize therapy. Pulmonary rehabilitation has been found to improve the physical efficiency of COPD patients. Therefore, we evaluated the effect of domiciliary pulmonary rehabilitation programme in patients of COPD. METHODS: Forty patients of stable COPD having severe airflow obstruction were included in the study. They were divided into control and experimental groups randomly. Rehabilitation included walking, breathing exercises, postural drainage, controlled coughing and changes in life style activities. Exercises of 30 minutes duration were performed at home twice daily for four weeks supervision. Six-minute walking distance, forced expiratory volume in one seocond (FEV1) and various indices of chronic respiratory disease questionnaire (CRDQ) were measured in both experimental and control groups before and after completion of the study. RESULTS: In the experimental group, after four weeks, the mean (+/- SD) difference in six-minute walking distance, dyspnoea, mastery, fatigue and emotion scores were 54.2 (26.7) meters, 0.96 (0.26), 0.89 (0.44), 0.90 (0.40) and 0.91 (0.32) respectively. Changes in all these parameters were statistically significant (p < 0.001) as compared to the control group. There was no significant change in FEV1. CONCLUSION: It was concluded that domiciliary pulmonary rehabilitation for four weeks results in significant improvement in the quality of life and exercise tolerance, even without improvement in FEV1.

Aged↗

PubMed1990

[Evaluation of late surgical results in coronary disease supported by exercise stress test, noninvasive examination and work resumption].

The aim of the study was to assess effectiveness of surgery in management of coronary artery disease (CAD) during long-term follow-up in bearings of physical efficiency and work resumption. 21 males observed during 3-7 years after coronary artery by-pass grafting (CABG) underwent the study. Patients age ranged from 37 to 60 years (mean 51.7) at the beginning of the follow-up. 10 patients had hypertension and 12 suffered from myocardial infarction before CABG. Number of by-pass grafts ranged from 2 to 4. Postsurgical rehabilitation was performed in the cardiological health resort hospital. Assessment was based on anamnesis and physical, ECG, noninvasive as well as ECG bicycle exercise stress examinations. Long-term follow-up proved significant postoperative increase of exercise tolerance expressed by prolongation of ECG exercise test duration as well as augmentation of maximal load and performed work. Left ventricular contractility improvement measured by LVET/PEP and LVETI parameters was also stated. The best results were observed up to 6 years after surgery in patients with grafted left anterior descending artery. Preoperative myocardial infarction did not effect on longterm results of surgery. 75% of patients resumed a work after myocardial revascularization.

Adult↗

PubMed1990

[Cardiopulmonary stress: control of the function of frequency variable pacemaker systems].

Based on the linear relationship between cardiac output and oxygen uptake direct breath-to-breath gas exchange measurements during exercise allow accurate determinations of cardiopulmonary function. We used cardiopulmonary exercise testing to assess the physiologic benefit of rate response VVIR pacing in 17 patients with chronotropic incompetence. 13 patients had an activity-rate-response pacemaker, two patients had a temperature-controlled pacemaker and two patients a respiratory-dependent system. Exercise testing was performed with the pacemaker, either programmed to fixed rate VVI or to rate variable VVIR pacing. All patients were exercised on a bicycle using a ramp protocol with 10 to 20 watts/min increments. Maximal oxygen uptake and the anaerobic threshold were determined. Compared with findings in the VVI mode, rate response VVIR pacing increased maximal exercise heart rate from 74 +/- 10 to 118 +/- 21 bpm (p less than 0.001). This increase in heart rate was associated with an increase of maximal oxygen uptake from 14.3 +/- 5 to 18.3 +/- 6 ml/kg per min (p less than 0.04) and a delay of the anaerobic threshold to a higher oxygen consumption of 14.6 +/- 5 vs 10.6 +/- 5 ml/kg per min (p less than 0.04). The individual increase in oxygen uptake was a direct function of the change in exercise heart rate independent of the implanted pacing device. The improved aerobic capacity resulted in a 17% increase in exercise tolerance and a 19% increase of exercise time. Cardiopulmonary exercise testing appears to be a useful noninvasive technique to quantify the cardiopulmonary benefit of rate response pacing.

Adult↗

PubMed1986

[Infantile cataract, hypertrophic cardiomyopathy and lactic acidosis following minor muscular exertion--a little known metabolic disease].

Three children from two unrelated families were found to be suffering from a hitherto little-known disorder. Infantile cataract was the primary symptom at the age of 3 months, progressed quickly and necessitated surgery. At the same age, muscular hypotonia was prominent and delayed gross motor development. At preschool and school ages muscle strength and exercise tolerance were reduced, and slight muscular exercise caused marked lactic acidemia. Subsequently, hypertrophic cardiomyopathy was discovered by echocardiography, though with no signs of cardiac obstruction at that time. There were no neurological symptoms. Intellectual development was normal. The disorder is inherited as an autosomal recessive. It can be recognized from the combination of infantile cataract, muscular hypotonia, cardiomyopathy, and lactic acidosis, which, however, must be looked for carefully. Early diagnosis is mandatory for genetic counseling. The ophthalmologist holds the key to diagnosis.

Acidosis, Lactic↗

PubMed1992

Portable liquid oxygen and exercise ability in severe respiratory disability.

BACKGROUND: The development of portable liquid oxygen systems, capable of delivering high flow rate oxygen for long periods, justifies reassessment of the value of supplemental oxygen to aid exercise tolerance in patients with chronic respiratory insufficiency. The type of exercise test and the low oxygen flow rates previously used may account for the variable and often poor responses to supplemental oxygen reported in earlier studies. METHODS: The walking tolerance of 30 patients with severe respiratory disability was measured while they were breathing air and increasing doses of supplemental oxygen (2, 4, 6 1/min) by using both the standard six minute walking test and an endurance walking test. To assess the initial learning effect and repeatability of the walking tests, three six minute walks and three endurance walks were performed on day 1 and a single walk of each type on days 2, 3, and 14. In addition, oxygen dosing studies were performed on days 2 and 3 after the initial baseline walking tests. Each dosing study comprised four endurance walking tests or four six minute walking tests with patients breathing either air at a flow rate of 4 1/min from a portable cylinder or supplemental oxygen at a flow rate of 2, 4 or 6 1/min from a portable liquid oxygen supply. The order of the tests was randomised. Walking distance with each flow rate of oxygen was compared with walking distance with patients carrying cylinder air and for the initial unburdened walks. Breathlessness was assessed by visual analogue scoring on completion of each walk. RESULTS: Exercise ability and breathlessness were significantly improved with supplemental oxygen and this benefit outweighed the reduction in performance resulting from carrying the portable device. Supplemental oxygen at flow rates of 2, 4, and 6 1/min increased mean endurance walking distances by 37.9%, 67.7% and 85.0% and six minute walking distances by 19.2%, 34.5%, and 36.3% by comparison with distances when the patient was carrying air with a flow rate of 4 1/min. The additional work of carrying the portable gas supply reduced endurance walking distance by 22.2% and six minute walking distance by 14.1% by comparison with a baseline unburdened walk. Comparison of supplemental oxygen at 2, 4, and 6 1/min with the baseline unburdened performance showed increased endurance walking distances of 7.3%, 30.4%, and 43.9% and six minute walking distances of 2.3%, 15.5%, and 17.0%. Walking distance was increased by more than 50% by comparison with an unburdened walk in seven patients with the endurance walking test but in only three patients with the six minute walking test. The benefit was similar in patients with obstructive and with interstitial lung disease. Individual responses were variable and only desaturation during the baseline walk in patients with obstructive lung disease had any predictive value for benefit with oxygen. CONCLUSION: As there was no clear relation between response to oxygen therapy and the patients' characteristics, assessment for supplemental oxygen therapy will depend on exercise testing. It is suggested that portable oxygen should be considered only if a patient shows a 50% improvement in exercise ability with high flow rate oxygen (4-6 1/min) by comparison with an unburdened walk.

Ambulatory Care↗

PubMed2002

The beneficial effects of total cavopulmonary conversion and arrhythmia surgery for the failed Fontan.

Postoperative Fontan patients can develop hemodynamic abnormalities and refractory atrial arrhythmias resulting in significant morbidity and mortality. We present our experience with total cavopulmonary artery conversion and arrhythmia surgery. Between 1994 and 2001, 41 patients underwent total cavopulmonary artery conversion and arrhythmia surgery. Significant hemodynamic lesions were repaired concomitantly: aortic aneurysm (n=1), atrioventricular valve insufficiency (n=8), and pulmonary artery stenosis (n=9). Thirty-five patients were in New York Heart Association class III or IV. Mean age at original Fontan was 7.5+/-6.5 years, at Fontan conversion, 18.7+/-9.0 years. Arrhythmia surgery for atrial re-entry tachycardia evolved from isthmus cryoablation (n=10) to right-sided maze (n=17). Maze-Cox III was used for 14 patients with atrial fibrillation. Atrial (n=34) and dual chamber (n=5) pacemakers were placed. Mortality and reoperation for bleeding rates are 0%. Chest tubes were removed on postoperative day 9.0+/-6.0. Mean hospital stay was 11.8+/-6.6 days. Three patients required cardiac transplantation at 8 days, 9 months, and 33 months postoperatively. There was one long-term death from acute myocardial infarction 2 years postoperatively. For the entire series, arrhythmia recurrence is 12.2% (5/41). Only 9.8% of patients (4/41) receive chronic antiarrhythmic medications; these patients were among the first eight in the series. Most patients are in New York Heart Association I or II. Bruce protocol in 12 patients showed increased tolerance (P<.05) Total cavopulmonary artery conversion with concomitant arrhythmia surgery is excellent therapy for patients with failed Fontan. It is safe, improves New York Heart Association class, improves exercise tolerance, and the incidence of recurrent arrhythmias is low.

Adolescent↗

PubMed2001

Baseline oxygen saturation predicts exercise desaturation below prescription threshold in patients with chronic obstructive pulmonary disease.

BACKGROUND: Recent studies of exercise-induced hypoxemia in patients with chronic obstructive pulmonary disease (COPD) have shown that oxygen supplementation during exertion increases exercise tolerance and alleviates dyspnea. Although measurements of forced expiratory volume in 1 second and diffusion capacity for carbon monoxide (DLCO) are known to predict exercise-induced desaturation in patients with COPD, baseline oxygen saturation has never been studied as a predictor of exercise-induced desaturation. METHODS: A retrospective analysis was performed of 100 consecutive patients with forced expiratory volume in 1 second-forced vital capacity ratio of 70% or less who underwent exercise testing for desaturation. Any desaturation to 88% or less with exercise was considered significant. Nineteen patients with total lung capacity of 80% or less were excluded to avoid evaluating those with combined obstructive and restrictive defects; 81 patients remained available for study. RESULTS: Nineteen (51%) of 37 patients with resting saturation of 95% or less desaturated with exercise as opposed to 7 (16%) of 44 with resting saturation of 96% or greater (P =.001). The sensitivity and the negative predictive value of baseline saturation of 95% or less as a screening test for exercise desaturation were 73% and 84%, respectively. If all patients with DLCO of 36% or less were excluded, 40 patients were left for study. Eight (40%) of 20 patients with baseline saturation of 95% or less compared with 0 of 20 with resting saturation of 96% or greater desaturated with exercise (P =.006). In this subset, the sensitivity and the negative predictive value of baseline saturation of 95% or less as a screening test for exercise desaturation both improved to 100%. CONCLUSIONS: In patients with COPD, baseline saturation of 95% or less is a good screening test for exercise desaturation, especially in patients with DLCO greater than 36%. This readily available office screening procedure merits further study in larger prospective patient cohorts.

Aged↗

PubMed1999

Physical activity and asthma.

The relationship between asthma and exercise and the resultant disability (ie, the impact on activities of daily living, including physical activity) shows wide interpatient and intrapatient variability, being influenced not only by the disease but additional psychosocial variables. There are a variety of helpful pharmacologic and nonpharmacologic measures in dealing with simple exercise-induced asthma, and new therapeutic options are being developed. The cardiorespiratory performance characteristics of asthmatic patients are very frequently suboptimal, either because of symptom-limited exercise tolerance or secondary deconditioning consequent upon inactivity. Medically supervised physical training can produce significant beneficial change. Recommendations for rehabilitation of asthmatic patients would include individualized exercise prescription and advice based on objective criteria of exercise capability, with flexibility in the programs offered, in order to cater to the broadest spectrum of patient disability.

Activities of Daily Living↗

PubMed1996

Dose response study of ipratropium bromide aerosol on maximum exercise performance in stable patients with chronic obstructive pulmonary disease.

BACKGROUND: Although the bronchodilating effect of inhaled anticholinergics has been established in patients with chronic obstructive pulmonary disease (COPD), their effects on exercise capacity are still controversial. Previous studies have suggested that the standard dosage hardly affects exercise tolerance, whereas higher doses might elicit an improvement. The aim of the present study was to determine the dose of ipratropium bromide aerosol that improves exercise performance using progressive cycle ergometry in patients with stable COPD. METHODS: Twenty men with stable COPD of mean (SD) age 69.2 (4.6) years and forced expiratory volume in one second (FEV1) 1.00 (0.37) 1 were studied in a randomised double blind manner. Each patient received ipratropium bromide in doses of 240 micrograms, 160 micrograms, 80 micrograms, 40 micrograms, and placebo from a metered dose inhaler (MDI) with an InspirEase spacer on five separate days. Spirometric parameters were assessed before and at 30, 60, 90, and 120 minutes after each inhalation, and pulse rate and blood pressure were also measured immediately before each spirometric measurement. Symptom limited progressive (20 watts/min) cycle ergometer exercise tests were performed 90 minutes after each inhalation. RESULTS: Ipratropium bromide in doses of 160 micrograms and 240 micrograms produced a greater increase in FEV1 than 40 micrograms or 80 micrograms ipratropium bromide at all time points. Doses of 160 micrograms and 240 micrograms ipratropium bromide also produced greater increases in maximal work load and maximal oxygen consumption than placebo, whereas 40 micrograms and 80 micrograms ipratropium bromide did not. There was a weak correlation between the change in FEV1 and the change in maximal work load (r = 0.45). No differences were found in pulse rate or blood pressure between the treatment and placebo groups, and no side effects were noted throughout the study. CONCLUSIONS: A dose of at least four times the standard dose of ipratropium bromide from an MDI with a spacer device was necessary to improve maximal cycle exercise capacity in patients with stable COPD. Although the data from cycle ergometry cannot be directly applied to exercise performed during day to day activities, it is conceivable that the recommended doses of ipratropium bromide do not elicit the optimal clinical benefits.

Aerosols↗

PubMed1994

Relation between coronary artery stenosis assessed by visual, caliper, and computer methods and exercise capacity in patients with single-vessel coronary artery disease. The Veterans Affairs ACME Investigators.

BACKGROUND: Practitioners often assume a close relation between angiographic coronary artery stenosis and patient functional capacity. To test this unproven hypothesis, we analyzed the relation between coronary artery stenosis measured by different methods and maximal treadmill exercise tolerance in patients with single-vessel disease before and after intervention by percutaneous transluminal coronary angioplasty (PTCA). METHODS AND RESULTS: Coronary angiography and maximal exercise testing off anti-ischemic medication were performed before random assignment of 227 patients with single-vessel coronary artery disease to PTCA or drug therapy. Six months later, angiography and exercise testing were repeated with patients assigned to PTCA off anti-ischemic therapy so that the altered coronary stenosis was the only consistent variable. Patients assigned to drug therapy were exercised on drug therapy. Coronary stenosis was assessed visually by the local investigator and quantitatively by blinded caliper and computer methods in central laboratories. Variabilities of caliper and computer measurements were established in a subset read twice. Visually estimated stenosis > or = 90% at baseline was associated with shorter exercise duration (7.9 versus 9.2 minutes, P < .04). Similar segregation at baseline was not observed with caliper or computer methods. Regardless of the method of measurement used, correlation between changes of lesion severity and exercise duration from baseline to follow-up was poor. Patients were angiographically classified as "better," "unchanged," or "worse" if follow-up stenosis was below, within, or above 2 SD of mean technical variability from baseline (+/- 18.8%, caliper, +/- 14.6%, computer). Exercise duration for PTCA patients improved among those with better lesions (+2.4 minutes, n = 50, P = .001) but also among those with unchanged lesions (+1.9 minutes, n = 41, P < or = .001). Unchanged medically treated patients improved less (+0.5 minutes, n = 86, P = .04). Results were similar when patients were angiographically classified by minimum lumen diameter. CONCLUSIONS: Handheld calipers and quantitative coronary angiography are equivalent techniques for making anatomic measurements. Neither method identified patients having reduced exercise capacity at baseline as well as visual estimation. The relation between changes of coronary stenosis and exercise duration is highly variable, at least in part because of the insensitivity of angiographic methods for detecting small but potentially important changes. Minimal anatomic improvement 6 months after PTCA does not preclude a good functional outcome. Contrary to common belief, angiographic stenosis does not correlate well with functional capacity, even in patients with single-vessel disease.

Angioplasty, Balloon, Coronary↗

PubMed1996

[Expired gas analysis--focused on VO2 max and anaerobic threshold].

Recently, expired gas analysis(EGA) during exercise testing is broadly performed. It has been recognized that anaerobic threshold(AT) and maximal oxygen uptake(VO2 max) may be useful in identifying one's exercise tolerance. AT especially has a good correlation with endurance capacity. In the field of sports medicine, the purposes of EGA are: 1) evaluation of endurance exercise capacity. 2) decision of intensity and frequency for exercise training, and 3) prevention of overtraining syndrome. In the clinical fields, EGA is frequently performed with cardiovascular patients, for example, myocardial infarction(MI), and congestive heart failure(CHF). The purposes are: 1) decision of intensity for exercise therapy with the patients of old MI. 2) evaluation of exercise capacity with the patients' of CHF. 3) index of exercise therapy for hypertension, hyperlipidemia, and diabetes, and 4) evaluation of drug effects including vasodilators and cardiotonics.

Anaerobic Threshold↗

PubMed1997

[Value and indications of exercise test in pneumology].

Exercise testing is the only integrate exploration technique, i.e., a technique which tests pulmonary, cardiac and muscular function, currently available in pneumology. The first indication for exercise testing in pneumology is to evaluate the exercise capacity of dyspnea patients. This can be done by measuring exercise tolerance and by differentiating each of the elements in the oxygen transport chain which can contribute to the dyspea, from a classical diagnostic standpoint, the exercise test can be used to screen for post-exercise asthma or a right-left shunt, estimate the severity of respiratory disease by demonstrating, for example, exercise-induced hypoxia. The exercise test also plays a fundamental role in preoperative evaluation prior to surgical resection of lung transplantation. It can also serve as a natural follow-up for treatment of respiratory diseases. One final and fundamental indication for exercise.

Exercise Test↗

PubMed2006

[Exercise training in cardiac patients: usefulness of the cardiopulmonary exercise test].

Exercise training is currently including in the treatment of coronary arterial disease patients, in patients with left ventricular dysfunction as well as in patients who underwent cardiac transplantation or cardiac surgery. However methods of prescribing exercise-training programs are difficult to determine and must be adapted for each patient Exercise test with gas analysis through the determination of anaerobic threshold may help to understand the physiopathological mechanism related to exercise limitation in these patients. Exercise test may help to precise exercise intensity during cardiac rehabilitation and may assess the benefits on exercise tolerance.

Exercise Test↗

PubMedDate not supplied

Long-term effects of cardiac rehabilitation and the paradigms of cardiac rehabilitation.

BACKGROUND: The benefits of exercise training for postmyocardial infarction and postcoronary artery bypass surgery patients are well established, but little is known about the effects of rehabilitation in the months or years following the program. The purpose of this study was to assess exercise capacity, blood lipids, and physical activity patterns 2 years after completing a concentrated residential rehabilitation program in Switzerland. METHODS: Seventy-eight patients (86% males, mean age = 56 +/- 10, mean ejection fraction = 64% +/- 12%) were referred to a residential rehabilitation program after a myocardial infarction or coronary artery bypass surgery between January 2001 and June 2001. Patients lived at the center for 1 month, during which time they underwent educational sessions, consumed a low-fat diet, and exercised 2 hours daily. Two years after completing the program, patients returned to the hospital and underwent a maximal exercise test, an assessment of recent and adulthood physical activity patterns, and evaluation of blood lipids. RESULTS: During the 2-year follow-up period, there were 5 deaths, and 70 of the remaining 73 patients returned for repeat testing. Mean exercise capacity increased 27% during the rehabilitation program (P < .01). Gains in exercise capacity during rehabilitation were maintained after the follow-up period; mean exercise capacity after 2 years was 34% higher compared with that at baseline (P < .01). At the 2-year evaluation, patients were expending a mean of 3127 +/- 1689 kcals/wk during recreational activities compared with 977 +/- 842 kcals/wk during adulthood prior to their cardiac event (P < .001). Between the completion of rehabilitation and the 2-year follow-up, total cholesterol, total cholesterol/high-density lipoprotein ratio, and triglycerides increased significantly. CONCLUSIONS: Two years after a cardiac event and participation in a concentrated residential rehabilitation program, patients maintained their exercise capacity and engaged in physical activities that exceed the levels recommended by guidelines for cardiovascular health. These observations suggest that a relatively intensive rehabilitation program provided a catalyst to maintain physical activity patterns and exercise tolerance in the 2 years following a cardiac event.

Coronary Artery Bypass↗

PubMed2002

[Effect of nutritional state on cardiopulmonary exercise performance in patients with chronic obstructive pulmonary disease].

OBJECTIVE: To explore the effect of nutritional state on cardiopulmonary exercise performance of chronic obstructive pulmonary disease (COPD) patients. METHODS: 43 COPD patients and 20 healthy controls performed incremental cardiopulmonary exercise testing with cycle ergometer. Nutritional assessment and routine lung function studies were performed in all subjects before testing. RESULTS: (1) Compared with the normally nourished COPD group, the malnourished group showed greater reduction in Wmax, VO(2)max, O(2)pulsemax, and AT (P < 0.05), whereas VO(2)/W/V(E) and DImax were higher in the malnourished group (P < 0.05). (2) IBW% was positively correlated with VO(2)max, Wmax, O(2)pulsemax, AT (r = 0.696, 0.432, 0.717, 0.822, P < 0.01), and negatively correlated with DImax and VO(2)/W/V(E) (r = -0.450, -0.640, P < 0.01) in COPD patients. CONCLUSION: Malnutrition adversely affected muscle aerobic capacity and exercise tolerance in COPD patients.

Adult↗

PubMed2004

Interval exercise versus continuous exercise in patients with moderate to severe chronic obstructive pulmonary disease--study protocol for a randomised controlled trial [ISRCTN11611768].

BACKGROUND: Physical exercise has become a cornerstone of management of chronic obstructive pulmonary disease (COPD) because it leads to clinically relevant improvements of exercise capacity and health-related quality of life (HRQL). Despite the scarcity of randomised trials directly comparing exercise protocols, current guidelines recommend high intensity continuous exercise for lower extremities as the probably most effective exercise modality. However, for patients admitted to inpatient respiratory rehabilitation programmes, it is often difficult to initiate such an exercise programme because they are severely limited by dyspnoea and leg fatigue and therefore unable to perform continuous exercise at higher intensities and for periods longer than 30 minutes. Interval exercise may be an attractive alternative for these COPD patients because it allows high intensity exercise with recovery periods. The aim of this study is to assess if interval exercise compared to high intensity continuous exercise is not of inferior effectiveness in terms of HRQL and exercise capacity improvements but associated with better exercise tolerance in patients with moderate to severe COPD at the beginning of a respiratory rehabilitation. METHODS/DESIGN: We will assign patients with moderately severe to severe COPD to either continuous exercise or interval exercise using a stratified randomisation. Patients will follow 12-15 exercise sessions during a comprehensive inpatient respiratory rehabilitation. Primary end point for effectiveness is HRQL as measured by the Chronic Respiratory Questionnaire (CRQ) two weeks after the end of rehabilitation and secondary endpoints include additional clinical outcomes such as functional exercise capacity, other HRQL measures, patients' experience of physical exercise as well as physiological measures of the effects of physical exercise such as cardiopulmonary exercise testing. Including expected drop-outs, we will need 52 patients per group to show differences corresponding to the minimal clinically important difference of the CRQ. Outcome assessors and investigators involved in data analysis will be blinded to group assignment until analyses have been carried out. DISCUSSION: Clinicians and the scientific community need evidence on the benefits and tolerance of exercise protocols available in clinical practice. The proposed trial will provide important and needed data on interval and continuous exercise for decision making in clinical practice.

Journal Article↗

PubMed2002

Angiotensin-converting enzyme genotype modulates pulmonary function and exercise capacity in treated patients with congestive stable heart failure.

BACKGROUND: The gene encoding ACE exhibits an insertion/deletion polymorphism resulting in 3 genotypes (DD, ID, and II), which affects serum and tissue ACE activity as well as other vasoactive substances. Pulmonary function is frequently abnormal in patients with congestive heart failure (CHF), the mechanism of which has not been completely characterized. ACE inhibition has been shown to improve diffusion across the alveolar-capillary membrane and to improve exercise capacity and gas exchange in CHF. The aim of the current study was to determine if ACE genotype is associated with altered pulmonary function and exercise intolerance in patients with treated CHF. METHODS AND RESULTS: Fifty-seven patients (stratified according to ACE genotype as 17 DD, 28 ID, 12 II) with ischemic and dilated cardiomyopathy, left ventricular ejection fraction (LVEF) <35%, and <10 pack-years of smoking history were studied. All patients were receiving standard therapy for left ventricular systolic dysfunction. Pulmonary function, LVEF, serum ACE, plasma angiotensin II, atrial natriuretic peptide, and brain natriuretic peptide were measured at baseline. Peak VO2 and gas exchange measurements were assessed with graded exercise. Resting LVEF was similar among the genotype groups (25% to 28%), and no differences were observed in diastolic function or pulmonary artery pressures (P>0.05). Mean peak VO2 and forced vital capacity (% Pred) were significantly reduced (P<0.05), whereas mean serum ACE activity and plasma angiotensin II concentration were highest in DD homozygotes. Subjects homozygous for the D-allele also demonstrated higher mean ventilatory equivalents for carbon dioxide (VE/VCO2) during exercise (P<0.05). CONCLUSIONS: ACE DD genotype is associated with decreased exercise tolerance in CHF, possibly mediated by altered pulmonary function. Pharmacological strategies effecting more complete inhibition of serum and tissue ACE and/or potentiation of bradykinin may improve exercise capacity in patients with CHF and ACE DD genotype.

Angiotensin II↗

PubMed1997

Lung volume reduction surgery improves maximal O2 consumption, maximal minute ventilation, O2 pulse, and dead space-to-tidal volume ratio during leg cycle ergometry.

Early experience suggests that lung volume reduction surgery improves exercise tolerance as measured by the 6-min walk distance in patients with emphysema. To identify the physiologic mechanism(s) by which lung volume reduction surgery improved exercise, we performed progressive cardiopulmonary exercise testing, including rest and peak exercise blood gas determinations, on 21 consecutive patients before and 3 mo after lung volume reduction surgery. Maximal work (median, range, % change) increased 17.5 watts (-13 to +44 watts, 46%, p < 0.05), maximal oxygen consumption increased 0.16 L/min (-0.17 to +0.48, 25%, p < 0.05), maximal ventilation increased 6.6 L/min (-7 to +26 L/min, 27%, p < 0.05), and the dead space/tidal volume ratio at peak exercise decreased 0.07 (-0.22 to +0.09, 12%, p < 0.05), exclusively as a result of an increase in the tidal volume. After lung volume reduction surgery heart rate decreased at the point of isowatt exercise, from 115 to 111 beats/min (p < 0.05). No difference was observed in the other physiologic variables measured at isowatt exercise. In 13 patients exercised while breathing room air, the alveolar-to-arterial O2 difference increased, and the arterial O2 tension decreased from rest to peak exercise both before and after the operation, but significant changes in this response were not observed after surgery. The primary problem limiting exercise performance in these patients was the limited ventilatory capacity as 16 and 13 of the 21 subjects developed acute respiratory acidemia at peak exercise before and after surgery, respectively. Lung volume reduction surgery in patients with severe emphysema improved maximal ventilation, thereby improving maximal exercise performance.

Exercise Test↗