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PubMed1979

Exercise testing in congenital aortic stenosis.

Treadmill exercise testing was performed on 23 patients with isolated congenital aortic stenosis. It was found that eight patients, with a negative exercise test and a normal rise in systolic blood pressure on exercise, had gradients less than 45 mmHg. Fifteen patients with gradients greater than 50 mmHg had positive exercise tests and their systolic blood pressure did not rise normally. It is suggested that the left heart studies to measure aortic valve gradients can safely be postponed if an exercise test is negative. Serial exercise testing of such patients will give an indication when left heart catheterization should be considered.

Adolescent↗
PubMed1986

Use of maximal bicycle exercise testing with respiratory gas analysis to assess exercise performance in patients with congestive heart failure secondary to coronary artery disease or to idiopathic dilated cardiomyopathy.

Analysis of respiratory gases during maximal treadmill exercise testing has been used in patients with congestive heart failure (CHF) to detect the lactate threshold, presumed to reflect the onset of skeletal muscle underperfusion, and maximal oxygen consumption (VO2), the point at which VO2 plateaus with increasing work due to exhaustion of peripheral oxygen delivery capacity. To determine if this approach is also useful during maximal bicycle exercise testing, ventilatory, hemodynamic and systemic lactate responses to bicycle exercise were measured in 48 patients with CHF. Ventilatory responses also were assessed in 12 normal subjects. Exercise increased VO2 to 24.8 +/- 3.9 ml/min/kg in normal subjects and 13.9 +/- 3.7 ml/min/kg in patients with CHF (p less than 0.001). In all but 1 patient the VO2 increment over the last 3 minutes of exercise was comparable to that in normal subjects exercising over identical work times, suggesting that maximal VO2 was not achieved. Moreover, in patients who exercised for less than 6 minutes, a ventilatory lactate threshold could not be identified. In the 33 patients who exercised longer, a ventilatory lactate threshold was identified in 31 and correlated well (r = 0.81) with blood lactate threshold, as defined by the VO2 at which lactate increased 5 mg/dl over rest levels. However, the 95% confidence limit for predicting blood lactate threshold from ventilatory data was +/- 200 ml/min, a large range relative to the measured ventilatory threshold (570 +/- 132 ml/min). These data suggest that in patients with CHF, respiratory gas analysis during maximal bicycle exercise cannot be used to measure maximal VO2 and provides only a general index of blood lactate behavior.

Cardiac Output↗
PubMed1988

The prognostic value of the exercise test.

Numerous investigators have demonstrated that responses to exercise testing enable prediction of the severity of underlying coronary disease and the patient's prognosis. However, exercise testing cannot predict angiographic findings or a poor prognosis with absolute certainty. Because survival can only be improved in specific clinical subsets of patients, it is important to carefully select for catheterization those in whom intervention can improve both quality and quantity of life. To deliver cost-effective health care, an effort has been made to use decision analysis to select those who should undergo cardiac catheterization. Decision analysis depends on reliable information regarding the predictive accuracy of the exercise test. Thus, this review is timely. Recent studies investigating the prognostic value of the exercise test are reviewed in this monograph. Patients include those recovering from a recent myocardial infarction (MI), those with stable coronary heart disease (including studies that have considered coronary angiographic findings, cardiac end points, and/or improved survival with coronary artery bypass surgery), and apparently healthy individuals. From this review, we conclude that silent ischemia induced by exercise testing in apparently healthy men is not as predictive of a poor outcome as once thought. Also, the use of the exercise test for screening is even more misleading than previously appreciated because of the higher rate of false positive results. Review of the 24 available studies of exercise testing in post-MI patients demonstrates that clinical judgment can be used to identify the high-risk patients, and that ST-segment shifts are not as predictive of high risk as an abnormal systolic blood pressure response or a poor exercise capacity. In patients with stable coronary heart disease, studies considering angiographic findings, cardiac events, and the differential outcome of coronary artery bypass surgery as compared with medical therapy have shown the exercise test to have prognostic power. From this perspective, it is obvious that there is much information supporting the use of exercise testing as the first noninvasive step after the history, physical examination, and resting electrocardiogram in the prognostic evaluation of patients with coronary artery disease. It accomplishes both purposes of prognostic testing: to provide information regarding the patient's status, and to help make recommendations for optimal management. The exercise test results help us make reasonable decisions for selection of patients who should undergo coronary angiography-including quality-of-life issues.(ABSTRACT TRUNCATED AT 400 WORDS)

Aged↗
PubMed1987

Single-chamber cardiac pacing with activity-initiated chronotropic response: evaluation by cardiopulmonary exercise testing.

In this study, sequential cardiopulmonary exercise testing was used to assess the physiologic benefits of a single-chamber ventricular pacing system that utilizes a piezoceramic sensor to adjust heart rate by detecting "physical activity." An initial exercise test was conducted with the pacemaker programmed (based on a randomization table) to either the fixed rate (VVI, 70 beats/min) or rate-variable (VVI-Act) mode, and the results were compared with those obtained during a second exercise test in which the pacemaker was programmed to the alternate pacing mode. A 1.5 to 2 hr rest period was permitted between exercise tests, each of which consisted of a symptom-limited constant speed (3.0 mph) Balke protocol with 2 min stages commencing at 0.0% grade with increments of 2.5% at end of each stage. Compared with findings during fixed-rate VVI pacing, VVI-Act pacing was associated with greater exercise-induced positive chronotropic response (mean maximum heart rate VVI-Act 128 +/- 15.3 beats/min vs VVI 90 +/- 28.4 beats/min; p less than .01), prolongation of exercise duration (VVI-Act 10.2 +/- 3.8 min vs VVI 7.7 +/- 2.5 min; p less than .01), increased peak oxygen consumption (VVI-Act 1617 +/- 656 ml O2/min vs VVI 1325 +/- 451 ml O2/min; p less than .01), and onset of anaerobic threshold at a higher oxygen consumption (VVI-Act 1208 +/- 343 ml O2/min vs VVI 1064 +/- 377 ml O2/min: p less than .01). Additionally, of 44 comparable exercise stages tested in the two pacing modes, perceived exertion (assessed by a numerical grading system) was lower in 38 of 44 instances during VVI-Act compared with VVI pacing.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1987

Exercise testing in juvenile borderline hypertension.

Exercise testing has emerged as an important method for improved evaluation of the cardiovascular system. However, juvenile patients presenting resting borderline hypertension have not been extensively studied. Therefore, this study evaluated the response to exercise in this group of patients. Nine hundred men aged 16 to 29 years performed a multistage near-maximal exercise test. The control group consisted of 338 age- and weight-matched, asymptomatic, healthy, normotensive individuals. Mean physical working capacity (+/- SD) was 129 +/- 28 W (82 +/- 18% of the normal according to our standardization) in the hypertension group, and 153 +/- 29 W (102 +/- 18%) in the control group (P less than 0.001). Mean systolic blood pressures at termination of exercise were 181 +/- 25 and 164 +/- 25 mm Hg in the hypertensive and the control groups, respectively; the mean diastolic values at termination of exercise were 49 +/- 32 and 32 +/- 29 mm Hg, respectively. The magnitude of the changes in blood pressure from rest to near-maximal values was smaller in the borderline-hypertensive individuals demonstrate a clear hypertensive pattern of reaction to physical activity, thus emphasizing the importance of exercise testing as part of the routine workup of such patients. The relationship between borderline hypertension and the risk of myocardial events has been established, and early hygienic or even pharmacological measures are necessary.

Adolescent↗
PubMed1988

The role of exercise testing in evaluation of arrhythmias.

Exercise testing has been widely applied for the evaluation of patients with coronary artery disease. The principles underlying its use for this indication make it a useful adjunctive technique, when combined with ambulatory monitoring, to diagnose arrhythmias and monitor antiarrhythmic drug therapy. During exercise, there is a withdrawal of vagal tone and a marked increase in circulating catecholamines and sympathetic inputs to the heart. These changes may directly cause arrhythmias (e.g., catecholamines can enhance automaticity and delayed afterpotentials and can shorten myocardial conduction time and refractory periods). However, they also augment myocardial oxygen demands by increasing myocardial inotropy, heart rate and blood pressure. Such changes may cause ischemia in patients with heart disease, which is a powerful stimulus for arrhythmia, or lead to dysfunction in left ventricular contraction and increased myocardial wall stress, factors that also may precipitate arrhythmia. In approximately 10% of patients with a history of serious arrhythmia, exercise represents the only means for exposing arrhythmia. Importantly, this technique is useful for evaluating the effect of antiarrhythmic drugs. These agents work by reducing membrane automaticity, slowing impulse conduction through the myocardium and prolonging membrane refractoriness. In contrast, catecholamines, which are secreted in response to exercise, have the opposite effect. Thus, exercise may negate the important effects of the antiarrhythmic drugs. Additionally, exercise testing may expose potentially serious toxic drug reactions that may not be obvious at rest. These include conduction abnormalities, negative inotropic effects, congestive heart failure and aggravation of arrhythmia. Although the presence and frequency of arrhythmia with exercise is highly variable in patients with benign arrhythmia, results are more consistent in patients with a history of serious arrhythmia. If arrhythmia is reproducibly provoked with exercise, this technique can be used to judge drug effect. Thus, exercise testing is an important, reliable and helpful technique for exposing arrhythmia, evaluating drug efficacy and identifying potentially serious toxic drug effects.

Anti-Arrhythmia Agents↗
PubMed1986

Prognostic significance of the treadmill exercise test performance 6 months after myocardial infarction.

A submaximal treadmill exercise test performed before hospital discharge after an uncomplicated myocardial infarction is often utilized to estimate prognosis and guide management, but there is little experience with a maximal exercise test performed 6 months after infarction to identify prognosis later in the convalescent period. The performance characteristics during an exercise test 6 months after myocardial infarction were related to the development of death, recurrent nonfatal myocardial infarction and coronary artery bypass surgery in the subsequent 12 months (that is, 6 to 18 months after infarction) in 473 patients. Mortality was significantly greater in patients who exhibited any of the following: inability to perform the exercise test because of cardiac limitations, the development of ST segment elevation of 1 mm or greater during the exercise test, an inadequate blood pressure response during exercise, the development of any ventricular premature depolarizations during exercise or the recovery period and inability to exercise beyond stage I of the modified Bruce protocol. By utilizing a combination of four high risk prognostic features from the exercise test, it was possible to stratify patients in terms of risk of mortality, from 1% if none of these features were present to 17% if three or four were present. Recurrent nonfatal myocardial infarction was predicted by an inability to perform the exercise test because of cardiac limitations, but not by any characteristics of exercise test performance. Coronary artery bypass surgery was associated with the development of ST segment depression of 1 mm or greater during the exercise test. Although clinical evidence of angina and heart failure 6 months after infarction was predictive of subsequent mortality among all survivors, among the low risk group without severely limiting cardiac disease, the exercise test provided unique prognostic information not available from clinical assessment alone. Therefore, a maximal exercise test performed 6 months after myocardial infarction is a valuable, noninvasive tool to evaluate prognosis. It provides information that is independent of and additive to clinical evaluation performed at the same time.

Adrenergic beta-Antagonists↗
PubMed1978

Detection of ventricular ectopy in patients with coronary heart disease and normal subjects by exercise testing and ambulatory electrocardiography.

Maximal exercise testing and 24-hour ambulatory electrocardiographic recording (Holter monitor) were utilized in the detection of ventricular ectopy in 90 patients with stable chronic coronary heart disease and in 30 normal subjects. Although the occurrence of any ventricular ectopic activity, as detected by either or both methods, was common, the incidence was significantly higher (P less than 0.001) in patients with coronary heart disease (86 percent; 77/90), as compared to that in normal subjects (40 percent; 12/30). Ventricular arrhythmia was more frequently detected by the 24-hour continuous electrocardiographic recording, being found in 70 of the 90 patients with coronary heart disease and in ten of the 30 normal subjects. In comparison, exercise testing disclosed ventricular ectopy in 56 of the 90 patients with coronary heart disease and in two of the 30 normal subjects. Multiform and repetitive patterns of ventricular ectopy were detected twice as commonly by continuous electrocardiographic recording than with exercise testing, and these patterns were present in one-half of the patients with coronary heart disease. Both methods of examination adjunctively disclosed more ventricular ectopy than either method alone.

Angina Pectoris↗
PubMed1985

Role of exercise testing in predicting sudden death.

The exercise test can be utilized to identify a subset of patients with coronary heart disease who are at increased risk of subsequent cardiac mortality including sudden cardiac death. The exercise test variables that best identify these high risk patients differ according to clinical subsets, but exercise duration, ST segment depression and ventricular arrhythmias on the electrocardiogram are the most important variables. In the clinical setting, the exercise test is of limited value for identifying the patient at risk for developing sudden cardiac death because its sensitivity and specificity are not high enough. However, the exercise test does provide prognostic information that is independent of other clinical variables and it may prove to be of clinical utility when combined with multiple other prognostic variables.

Arrhythmias, Cardiac↗
PubMed1989

[The clinical significance of the low level treadmill exercise test in acute myocardial infarction].

To clarify the clinical significance of the exercise test in acute myocardial infarction (AMI), the relationship between the results of exercise test and clinical features was studied. The low level treadmill exercise test (maximum exercise time was 1080 seconds and the maximum oxygen consumption was 7 METs) were performed in 111 patients within 2 months after the onset of AMI. The exercise time, the endpoint of the exercise test, the exercise-induced ST-segment deviation and ventricular premature beats (VPC) were evaluated from the exercise tests. Among the clinical features, age, sex, the severity in the acute period (Killip's classification and Forrester's hemodynamic subset), the findings in cardioangiography (the number of diseased coronary arteries, left ventricular ejection fraction and abnormal wall motion in the left ventricle) and short term prognosis after AMI were evaluated. The prognosis was judged as poor when cardiac death, congestive heart failure, postinfarction angina, the decrease of exercise tolerance and reattack of AMI occurred, or when an aorto-coronary bypass graft or percutaneous transluminal coronary angioplasty was performed. The exercise time was shorter in patients over the age of 60 years (578 +/- 360 seconds) than in younger patients (818 +/- 296 seconds), and also in females (487 +/- 392 seconds) than in males (767 +/- 319 seconds). The patients classed as Forrester's hemodynamic subset IV had shorter exercise time than the others. But, there was no relationship between the exercise time and Killip's classification. Low left ventricular ejection fraction (55% or less) was associated with short exercise time and the apperance of exercise-induced VPC. But the number of diseased coronary artery and abnormal wall motion in the left ventricle were not related to the exercise test. The patients with high exercise tolerance (4.2 METs or more) in the AMI recovery period showed better prognosis than those with low exercise tolerance within one year after AMI (96% vs 50%, p less than 0.0001, respectively). In conclusion, the low level exercise test in AMI was influenced by age, sex and cardiac function, and it was useful in evaluating the short term prognosis after AMI.

Adult↗
PubMed1991

Respiratory gas exchange during treadmill exercise testing: reproducibility and comparison of different exercise protocols.

Ten subjects performed 4 maximal exercise tests to evaluate reproducibility and effects of treadmill inclination on submaximal and maximal oxygen consumption. They performed a standard Bruce protocol twice, and 1 protocol with progressive speed increase with constant, or without, inclination. At maximal exercise there was no significant difference between the protocols in oxygen consumption, respiratory gas exchange ratio, minute ventilation, plasma lactate, serum potassium or heart rate. Exercise time and treadmill distance were shorter than Bruce protocol with inclination, and considerably prolonged without. Reproducibility for Bruce protocol was good for group comparison of oxygen consumption throughout exercise. The individual variations for oxygen consumption were small at maximal exercise, but were considerable at rest and at the lowest exercise steps, this was slightly improved by analysing longer sampling time. Thus, measurement of oxygen consumption is reliable for group analysis, but interpretation must be careful in individuals unless maximal exercise is obtained. Treadmill inclination may be adjusted according to individual preferences.

Adolescent↗
PubMed1988

Lack of diurnal variation in maximal symptom-limited exercise test response in chronic stable angina.

Exercise testing is widely used to evaluate the effects of anti-ischemic drugs. Many studies have reported good reproducibility when it is performed in the morning, but little information is available regarding the diurnal variation of exercise test response in patients with chronic stable angina. With the advent of new long-acting anti-ischemic drugs, it has become necessary to perform the exercise testing at various times of the day to determine the duration of action of a given drug. To examine the diurnal variation, exercise tests were performed on 41 patients, aged 53 to 75 years, with established chronic stable angina on 2 occasions 5 days apart at 10 A.M. and 4 P.M. on each day. On day 1, the mean +/- standard error of the mean exercise time was 5.0 +/- 0.4 minutes at 10 A.M. and 5.1 +/- 0.4 minutes at 4 P.M., and on day 5, it was 5.6 +/- 0.4 minutes at 10 A.M. and 5.5 +/- 0.4 minutes at 4 P.M. These values did not differ in statistical significance. Similarly, the time to the development of 1 mm of ST-segment depression did not show any statistically significant change during either test period on either day nor did maximal ST-segment depression. Heart rate at rest was 79 +/- 3 beats/min at 10 A.M., 81 +/- 3 beats/min at 4 P.M. on day 1 and 78 +/- 2 beats/min at 10 A.M. and 80 +/- 3 beats/min at 4 P.M. on day 5 (difference not significant). Similarly, no significant changes were observed in maximal heart rate or rate-pressure product at peak exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1989

The safety of maximal exercise testing.

Previous reports on the safety of exercise testing have been based on surveys from different testing facilities with a variety of testing protocols and patient types. From 1971 through 1987, 71,914 maximal exercise tests conducted in a population with a low prevalence of known coronary heart disease under uniform conditions at a single medical facility resulted in six major cardiac complications including one death. No complications have occurred in the past 10 years in 45,000 maximal tests. The overall cardiac complication rate in men and women is 0.8 complications per 10,000 tests with 95% confidence intervals of 0.3-1.9 complications per 10,000 tests. Maximal exercise testing appears safer than some previously published reports have suggested and seems to be getting safer with time.

Accident Prevention↗
PubMed1987

Implications of positive treadmill exercise tests in asymptomatic adult African blacks.

Maximal exercise tests in 225 apparently healthy adult Africans (148 men, 77 women) aged 26 to 70 years revealed 35 subjects (18 men and 17 women) with ischaemic ST changes. Out of these, 6 men and 4 women developed chest pain that necessitated termination of the tests. Significant ventricular arrhythmias were observed in 27 patients (20 men and 7 women) all of whom had an otherwise negative response to exercise tests. During a follow-up period ranging from 6 months to 4 years, 2 male positive-responders--both of whom developed chest pain during exercise testing--sustained acute myocardial infarction. The coronary arteries of both men were found to be normal at coronary angiography. A third male positive-responder, who also developed chest pain during exercise testing, subsequently experienced repeated attacks of angina with no ECG or serum enzyme changes. Coronary angiography, in this patient, revealed significant proximal vessel disease necessitating coronary angioplasty. One female positive responder, who developed chest pain during exercise-testing, experienced episodes of restrosternal discomfort of considerable duration with no ECG or serum enzyme changes. Her coronary arteries were subsequently shown to be normal. While coronary artery disease would no doubt account for a significant percentage of positive exercise responses in adult African blacks, it seems likely that non-coronary causes play a dominant role.

Adult↗
PubMed1984

Submaximal exercise testing early after myocardial infarction. Prognostic importance of exercise induced ST segment elevation.

Seventy four patients (66 men, eight women; mean age 54.3 years) underwent submaximal exercise testing 7-23 days (mean 10.7) after acute myocardial infarction. Follow up was a mean period of 11.3 months. When compared with patients with no exercise induced abnormality, ST segment elevation, ST shift (depression or elevation or both), ST depression, inability to complete five metabolic equivalents, and inadequate blood pressure response to exercise were predictive of subsequent cardiac events (cardiac death, left ventricular failure, recurrent myocardial infarction, angina). When the presence or absence of specific variables was assessed, only ST elevation and ST shift predicted subsequent cardiac events. The presence of exercise induced ST elevation was the only exercise test variable which predicted cardiac death. ST segment elevation was, therefore, the exercise induced abnormality which best predicted the risk of future complications.

Adrenergic beta-Antagonists↗
PubMed1978

[Hyperventilation test in coronary disease: a comparison with a bicycle ergometer exercise test. Report of 100 cases].

A hundred cases have been studied and divided into three categories:--60 normal subjects;--30 coronary subjects with a positive exercise test;--10 subjects with defective nervous control of the circulation; using the exercise test, we studied the effects of hyperventilation on repolarisation of the ventricle. In the normal subjects there was no ischaemic depression of the ST segment, but there were minor changes in repolarisation which affected the T wave in 73% of subjects and were essentially posterior in distribution. In the coronary subjects, we found three with ischaemic depression of the ST segment and one with ST elevation of 2.5 mm (6.7% of the coronary subjects). This last finding is evidence against the commonly held hypothesis that reproduction of ST depression by hyperventilation during the exercise test indicates a false positive test. In the patients with defective nervous control of the circulation, 9 had an ischaemic type of ST depression, either as a new feature or as a more severe one compared with that found at rest. The mechanism by which these depressions are produced has not been totally explained:--in the cases with defective nervous control of the circulation, it appears that latent increased sympathetic activity is increased by the hyperventilation;--in the coronary subjects, it may be caused by true ischaemia or by an associated defect in nervous control of the circulation.

Adult↗