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At least 505 records · Page 28Linked to original sources

PubMed2003

Relationship between impaired chronotropic response, cardiac output during exercise, and exercise tolerance in patients with chronic heart failure.

The present study was undertaken to investigate the relationship between the extent of impaired chronotropic response and cardiac output during exercise, and exercise tolerance in patients with chronic heart failure. The subjects consisted of 24 patients (mean 60.1 +/- 14.0 years) who had mild chronotropic incompetence. Cardiopulmonary exercise testing was performed in all patients, and heart rate (HR), anaerobic threshold (AT), maximum oxygen uptake (peak VO2), slope of the regression line relating the ventilatory equivalent to carbon dioxide output (VE/VCO2 slope), and exercise time were measured. Cardiac output (CO) was measured by a thoracic bioimpedance method and cardiac index (CI) was calculated. Plasma norepinephrine (NE) was measured at rest and immediately after the exercise test. The changes in HR, NE, and CI from the resting state to immediately after exercise were calculated as deltaHR, deltaNE, and deltaCI, respectively. The deltaNE was converted to a logarithmic scale and deltaHR/log deltaNE was used as a parameter of HR response to sympathetic nerve stimulation. The results were as follows: HR and NE in the resting state had no correlation with AT and with peak VO2. DeltaHR/log deltaNE correlated positively with both AT and peak VO2, and negatively with the VE/CO2 slope. DeltaHR/log deltaNE correlated positively with peak CI, %deltaCI, and deltaCI/exercise time. The data suggest that one of the mechanisms of low exercise tolerance in chronic heart failure patients was due to an inadequate increase in CO response against exercise caused by an impaired HR response to increased NE.

Adult↗

PubMed2004

Effects of exercise training after open heart surgery on quality of life and exercise tolerance in patients with mitral regurgitation or aortic regurgitation.

We conducted a questionnaire survey regarding quality of life (QOL) to evaluate the effects of exercise training on the QOL in patients with valvular heart disease after surgery. This study included 64 consecutive patients who underwent heart surgery. They were divided into two groups: exercise training could (EX(+) group, n = 31) and could not be performed (EX(-) group, n = 33) until 6 months after surgery. To evaluate the QOL and exercise tolerance, we employed "a questionnaire regarding disease and quality of life" developed for Japanese people and cardiopulmonary exercise testing. In our questionnaire survey, the improvement rating (Delta subjective/social index), which was calculated from the difference between the pre-and postoperative values, was greater in the EX(+) group than that in the EX(-) group (4.9 +/- 3.1 versus 1.1 +/- 4.0, P < 0.05). In the changes in exercise tolerance, Delta anaerobic threshold was greater in the EX(+) group (0.79 +/- 0.17 versus -0.02 +/- 0.28, P < 0.01). Moreover, there was a positive correlation between Delta subjective/social index and Delta peak VO(2) (r = 0.62, P < 0.05). We concluded that exercise training for patients after cardiac surgery improves the QOL and exercise tolerance. It is suggested that changes in subjective and social parameters contribute to an exercise training-related improvement in the QOL.

Aged↗

PubMed2000

Contribution of the peak exercise QT dispersion to the accuracy of an exercise test during the evaluation of coronary artery disease.

OBJECTIVE: Regional defects in ventricle repolarization are extremely sensitive to ischaemia which can be measured as QT dispersion (QTd). We investigated the role of QTd calculated at the time of peak exercise during treadmill studies. METHODS AND RESULTS: Thirty-three women and eighty men, whose treadmill test results and coronary angiography studies had been examined, were divided into four groups according to the test results: 1) subjects with a negative treadmill test and without significant stenosis results in the angiography, were considered normal (N; n = 35); 2) subjects with both a positive exercise test and a significant presence of stenotic coronary arteries, were considered true positive (TP; n = 52); 3) subjects with a positive exercise test, but without significant stenosis results in the angiography, were considered false positive (FP; n = 14); 4) subjects with a negative treadmill study, despite significantly stenotic arteries, were considered false negative (FN; n = 12). All subjects were evaluated on the basis of age, significant ST-segment depression, peak heart rate, rest and peak exercise QT, and QpT (measured from the beginning of the QRS complex to the highest point of the T wave) dispersion, and corrected (QTcd, QpTcd) values for heart rate. The most significant differences were observed between the N and the TP groups in terms of QTd and QTcd (p < 0.01), with a higher correlation (r = 0.48). A significant relationship was also observed in terms of QpT and QpTcd values during peak exercise (p < 0.01). The sensitivity of the peak exercise QTcd and QTcd > or = 70 ms in determining coronary artery disease was found to be 74%. In cases of QTcd > or = 70 ms, in addition to ST-segment depression, the test was found to be less sensitive, but more specific at 96%. CONCLUSION: It suggests that when peak exercise QTd and QpTd values are taken into account, with the exception of the ST-segment depression, the accuracy of the exercise test will increase and false positive results will decrease.

Adult↗

PubMed2026

Effects of Hydrogen-Rich Water Supplementation on Exercise Performance, Autonomic Nervous System Recovery, and Blood Lactate Concentration During Repeated Sprint Exercise in Male University Athletes.

Hydrogen-rich water (HRW) supplementation has been proposed to exert anti-fatigue effects during exercise; however, its impact on exercise performance and autonomic nervous system (ANS) function during repeated sprinting remains unclear. The aim of this study was to examine the effects of acute pre-exercise HRW ingestion on repeated sprint performance, ANS regulation, and blood lactate concentration. This randomized, single-blind, placebo-controlled crossover study included 13 male university athletes (23.9 ± 2.0 years). Each participant completed two sessions of 7×6-second all-out cycling sprints interspersed with 30-second recovery intervals, with a one-week washout period between sessions. Critical flicker fusion frequency, heart rate, heart rate variability (HRV), and blood lactate were assessed at baseline, during exercise, and at 0-5 min and 10 min post-exercise. Compared to the placebo trial, the HRW trial demonstrated significantly higher average power output (d = 0.61) and significantly lower total work decrement and fatigue index (d = 0.62; d = 0.64). Post-exercise HRV recovery was significantly accelerated in the HRW trial, including RMSSD (d = 0.62), LF/HF ratio (d = 0.82), SampEn (d = 0.79), and DFAα1 (d = 0.79). Blood lactate at 3 min post-exercise was approximately 1 mmol/L lower in the HRW trial (d = 0.64). These findings suggest that acute HRW ingestion attenuates the decline in power output, accelerates ANS recovery, and enhances lactate clearance following repeated sprint exercise.

Humans↗

PubMed2004

Effect of moderate exercise on excess post-exercise oxygen consumption and catecholamines in young women.

AIM: The purpose of this study was to examine the effects of moderate exercise on the magnitude and duration of excess post-exercise oxygen consumption (EPOC) and catecholamine concentrations in 7 young women. METHODS: The subjects performed 30 or 60 minutes of exercise (30-ME and 60-ME, respectively) on separate days at an intensity of 60% of maximal oxygen uptake on a cycle ergometer. The glucose, epinephrine and norepinephrine in the plasma, and free fatty acids and glycerol in the serum were measured at the end of the 60 min of the rest period before each exercise, immediately after the performance of each exercise and 30 min, 1, 2 and 24 h time points after each exercise. RESULTS: EPOC lasted for 46.1+/-25.4 and 116.1+/-79.8 min after the 30- and 60-ME, respectively. Corresponding total EPOC were 2636+/-1125 and 5208+/-1880 ml, respectively. The mean differences were statistically significant (p<0.05 each). The serum free fatty acids significantly increased immediately after the 60-ME. The serum glycerol was significantly increased immediately after the 30-ME and was also significantly increased immediately after and 30 min time point after the 60-ME. The plasma epinephrine and norepinephrine significantly increased immediately after the 30- and 60-ME, respectively. The plasma epinephrine at the 30 min time point after the 60-ME significantly correlated with the magnitude (r=0.955) and duration (r=0.897) of EPOC. Norepinephrine at the 30 min time point after the 60-ME also significantly correlated with the magnitude (r=0.774) of EPOC. CONCLUSION: The results indicate that longer duration exercise results in a greater and longer EPOC, and the plasma catecholamines may possibly contribute to EPOC in young women. Although, the overall magnitude of EPOC is small, if exercise frequency and compliance are strong, some long term benefits may accrue.

Adult↗

PubMed2006

[Cardiopulmonary exercise test in the evaluation of exercise capacity in patients with Ebstein anomaly and patent ostium secundum atrial septal defect aged over 30 years].

UNLABELLED: There are few data available on applying the cardiopulmonary exercise test for evaluation of cardiac exercise capacity in adult patients with congenital heart diseases. The aim of the study was to perform this test in adults with Ebstein anomaly and patients with patent ASD II (atrial septal defect) and determination of potential relationships between these parameters and echocardiographically assessed hemodynamic indices. MATERIAL AND METHODS: Twenty patients with Ebstein anomaly mean aged 40.3 +/- 12.3 years were studied. Control group consisted of 19 individuals at mean age of 39.9 years. Echocardiography was performed for the evaluation of severity of the disease. Additionally, 36 patients with ASD II were included, mean age 44.7 +/- 8.2 years. The control group consisted of 25 individuals at mean age of 45.6 years. Maximum exercise treadmill test was carried out and resting and exercise spirometry. RESULTS: Ebstein anomaly. Maximum oxygen uptake, minute ventilation, maximum heart rate and blood pressure at peak exercise were significantly lower in study patients than in control group. VE/VCO2 was increased. No differences were observed between groups with respect to spirometric parameters. Oxygen uptake decreased along with the severity of the disease. ASD II. Maximum oxygen uptake, minute ventilation, maximum heart rate and blood pressure at peak exercise and spirometric parameters were significantly lower in study patients than in control group. Significant negative correlations were shown for VO2 (maximum oxygen uptake) and Qp:Qs (pulmonary to systemic flow ratio) (p = 0.004), maximum heart rate - HRmax and HRmax% and RV (end-diastolic right ventricular diameter) (p = 0.02 i p = 0.01), RV and systolic pressure at peak exercise (p = 0.03), obstruction marker FEV1 and RV (p = 0.04) and between RVSP (right ventricular end-systolic pressure) (p = 0.01). Negative correlation was observed between RQ (respiratory quotient) and RVSP (p = 0.004), and positive correlation between HRmax and VO2 (p = 0.005). CONCLUSIONS: The exercise capacity of adults with Ebstein anomaly and those with patent ASD II is significantly reduced. It decreases along with the echocardiographic severity of the disease in Ebstein anomaly patients and it seems to result from the right ventricular volume overload in patients with patent ASD II.

Abnormalities, Multiple↗

PubMed1991

Effect of beta-blockers on exercise physiology: implications for exercise training.

We conducted a series of studies aimed at investigating the effect of beta-blockers on exercise physiology. On the basis of these and other existing studies, it is possible to draw the following conclusions and to make the following tentative recommendations for patients engaged in exercise training who receive beta-blocker therapy: i) CAD patients treated with beta-blockers are capable of deriving the expected enhancement of cardiorespiratory fitness during training, irrespective of the type of drug used; ii) beta1-selective blockers are preferable to nonselective agents for hypertensive patients engaged in exercise training; iii) because beta1-selective blockers impair exercise tolerance in some hypertensive patients, physicians should look out for this adverse reaction and, if present, consider alternative antihypertensive therapy; iv) intrinsic sympathomimetic activity confers no advantage during exercise training; v) exercise intensity prescription for patients receiving beta-blockers should be in accordance with traditional guidelines and based on results of individualized exercise testing performed on medication; vi) exercise training is desirable during beta-blocker therapy in that it appears to offset adverse alterations in lipoprotein metabolism; and vii) nonselective beta-blockers may increase predisposition to exertional hyperthermia, and patients must therefore be encouraged to adhere strictly to accepted guidelines for heat injury prevention.

Adrenergic beta-Antagonists↗

PubMed1993

Relative contraction force producing a reduction in calf blood flow by superimposing forearm exercise on lower leg exercise.

The relative contraction force producing a reduction in exercise hyperaemia was studied by superimposing handgrip contraction at different intensities on plantar flexion of low intensity. Ten active women served as subjects. Blood flow to the forearm (Qforearm) and calf (Qcalf) was measured with mercury-in-rubber strain gauges by venous occlusion plethysmography immediately after 60 s of rhythmic plantar flexion at 10% of maximum voluntary contraction (MVC), which was expressed as P10H0, or combined plantar flexion and handgrip contraction. In the combined exercise, handgrip exercise at 30%, 50% or 70% MVC was added to plantar flexion during the last 30 s of exercise (P10H30, P10H50 and P10H70, respectively). The Qforearm increases after P10H30, P10H50 and P10H70 were significantly larger (P < 0.01) than that after P10H0, and the difference between P10H30 and P10H70 was also significant (P < 0.01). Immediate post-exercise Qcalf after P10H0 increased by 7.4 (SEM 0.9) ml x 100 ml-1 x min-1. When handgrip contraction at 70% MVC was added, the Qcalf increase after exercise [4.5 (SEM 0.7) ml x 100 ml-1 x min-1] was significantly lower than after plantar flexion alone (P < 0.05). However, no significant change was found in Qcalf when the forces of added handgrip contraction were 30% and 50% MVC, although the mean value of Qcalf increase was lower after P10H50 combined exercise. Calf vascular resistance calculated as BP/Qcalf (BP mean blood pressure) tended to increase after P10H70 to a nonsignificant extent. Heart rate and oxygen uptake in these exercises increased when handgrip contraction at 30%, 50%, or 70% MVC was added to plantar flexion at 10% MVC.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed2002

Influence of acute exercise on human platelet responsiveness: possible involvement of exercise-induced oxidative stress.

The aim of this study was to evaluate in sedentary male subjects the effects of an acute bout of strenuous and moderate exercise on ex vivo platelet responsiveness and its possible relationship with exercise-associated modifications of oxidant-antioxidant status. An increased ADP- and collagen-evoked platelet aggregation associated with modified membrane fluidity and ion homeostasis was observed after exhaustive exercise. After moderate exercise, we found a decrease of platelet aggregation evoked by low concentrations of agonists. Strenuous exercise, but not moderate exertion, resulted in the enhanced accumulation of secondary products of lipid peroxidation, decreased total antioxidant capacity, including a diminished superoxide dismutase activity, and increased susceptibility of low-density lipoprotein (LDL) to in vitro oxidation. Acute elevation of plasma nitrite/nitrate (NOx) content was observed following each single session of physical test, whilst the platelet NOx content was decreased after strenuous exercise and increased after moderate exercise. Findings of the present study suggest that oxidative stress induced by acute strenuous exercise may interfere with platelet responsiveness most likely by promoting oxidized LDL-mediated platelet activation and by decreasing plasma and platelet-derived nitric oxide (NO) bioactivity. Moreover, our results further suggest that platelet responsiveness following an acute moderate physical stressor may depend on the efficiency of plasma and intraplatelet NO to desensitize platelets to agonist stimulation.

Adenosine Diphosphate↗

PubMed2003

The effect of prolonged submaximal exercise on gas exchange kinetics and ventilation during heavy exercise in humans.

This study compared ventilation, gas exchange (oxygen uptake, VO(2)) and the surface electromyogram (EMG) activity of four major lower limb muscles during heavy exercise before (Pre-Ex) and after (Post-Ex) a sustained 90-min cycling exercise at 60% VO(2peak). The 90-min exercise was incorporated under the hypothesis that sustained exercise would alter substrate availability in the second exercise bout causing differences in fibre recruitment patterns, gas exchange and ventilation. Nine trained male subjects [VO(2peak)=60.2 (1.7) ml.kg(-1).min(-1)] completed two identical 6-min bouts of cycling performed at high intensity [approximately 90% VO(2peak); 307 (6) W, mean (SE)]. Ventilation and gas exchange were measured breath-by-breath and the EMG was recorded during the last 12 s of each minute of the two 6-min bouts. EMG signals were analysed to determine integrated EMG (iEMG) and mean power frequency (MPF). VO(2) at min 3 and min 6 in Post-Ex were significantly higher (i.e., +201 and 141 ml.min(-1), respectively, P<0.05) than in Pre-Ex but there was a approximately 25% decrease of the slow component, taken as the difference between min 6 and min 3 [187 (27) vs 249 (35) ml.min(-1), respectively, P<0.05]. The greater whole-body VO(2) after 3 min of exercise in Post-Ex was not accompanied by clear alterations in the iEMG and MPF of the examined leg muscles. Ventilation and heart rate were elevated (approximately 12-16 l.min(-1) and approximately 10 beats.min(-1), respectively, P<0.05) as were the ratios V(E)/O(2) and V(E)/VCO(2) in the Post-Ex tests. It was concluded that the VO(2) and ventilation responses to high-intensity exercise can be altered following prolonged moderate intensity exercise in terms of increased amplitude without associated major changes in either iEMG or MPF values among conditions.

Adult↗

PubMed1997

Dehydration in soldiers during walking/running exercise in the heat and the effects of fluid ingestion during and after exercise.

The aim of this study was to examine whether ingesting water alone, or dextrose (7.5 g x 100 ml(-1)) with electrolytes, or fructose/corn solids (7.5 g x 100 ml(-1)) (400 ml every 20 min) would reduce the perceived exertion associated with 16 km (3 h) walking/running in the heat compared with that perceived during exercise with no fluid intake. Perceived exertion was assessed at 1-h intervals during exercise. Blood samples, required for analysis of blood glucose, plasma sodium, plasma osmolality and plasma volume, were obtained prior to exercise and at 1-h intervals during the exercise; further samples were obtained 1-h intervals for 3 h following the exercise. Drinking fluids at regular intervals reduced the level of perceived exertion. In the test during which no fluid was ingested, body mass decreased by 4.9 (0.4) kg [mean (SEM)], but decreased less with ingestion of either the dextrose/electrolytes or fructose/corn solids solutions, or water alone [1.3 (0.2) kg, 1.6 (0.3) kg and 2.0 (0.1) kg, respectively]. Plasma volume fell by 17% when taking no fluid, but fell less when ingesting fluids. Blood glucose fell significantly (P < 0.01) when taking no fluid and rose to 8.4 (1.3) mmol x l(-1) (P < 0.001) and 6.8 (1.1) mmol x l(-1) (P < 0.01) with ingestion of the dextrose/electrolytes or fructose/corn solids solutions, respectively. Urine output was greater with ingestion of water than with any of the other drinks. Six subjects experienced fatigue during exercise with no fluid and failed to complete the exercise. These results suggest that fatigue was caused by several interacting factors: a fall in blood glucose and plasma volume, dehydration, and neuroglycopenia. Taking fluids during exercise reduced the strain and the rating of perceived exertion; this was better achieved by ingesting a dextrose/electrolytes solution.

Adult↗

PubMed1999

Effect of exercise modality on oxygen uptake kinetics during heavy exercise.

The mechanisms responsible for the oxygen uptake (VO2) slow component during high-intensity exercise have yet to be established. In order to explore the possibility that the VO2 slow component is related to the muscle contraction regimen used, we examined the pulmonary VO2 kinetics during constant-load treadmill and cycle exercise at an exercise intensity that produced the same level of lactacidaemia for both exercise modes. Eight healthy subjects, aged 22-37 years, completed incremental exercise tests to exhaustion on both a cycle ergometer and a treadmill for the determination of the ventilatory threshold (defined as the lactate threshold, Th1a) and maximum VO2 (VO2max). Subsequently, the subjects completed two "square-wave" transitions from rest to a running speed or power output that required a VO2 that was halfway between the mode-specific Th1a and VO2max. Arterialised blood lactate concentration was determined immediately before and after each transition. The VO2 responses to the two transitions for each exercise mode were time-aligned and averaged. The increase in blood lactate concentration produced by the transitions was not significantly different between cycling [mean (SD) 5.9 (1.5) mM] and running [5.5 (1.6) mM]. The increase in VO2 between 3 and 6 min of exercise; (i.e. the slow component) was significantly greater in cycling than in running, both in absolute terms [290 (102) vs 200 (45) ml x min(-1); P<0.05] and as a proportion of the total VO2 response above baseline [10 (3)% vs 6 (1)%; P < 0.05]. These data indicate that: (a) a VO2 slow component does exist for high-intensity treadmill running, and (b) the magnitude of the slow component is less for running than for cycling at equivalent levels of lactacidaemia. The greater slow component observed in cycling compared to running may be related to differences in the muscle contraction regimen that is required for the two exercise modes.

Adult↗

PubMed2002

Exhaled nitric oxide level during and after heavy exercise in athletes with exercise-induced hypoxaemia.

Endogenous nitric oxide (NO) is an important mediator of vasodilatation, bronchodilatation and lung inflammation. We hypothesised that the exhaled NO level may be modified in some endurance-trained athletes during and after intense exercise. Nine athletes with exercise-induced hypoxaemia (EIH), 12 athletes without EIH and 10 untrained subjects exercised for 15 min at 90% maximal oxygen consumption (VO(2)max). Exhaled NO was measured during exercise, and after 1 h and 22 h of recovery. Exhaled NO concentration ( C(NO)) decreased significantly during exercise in all subjects and returned to basal values after 1 h of recovery with no further modification. Exhaled NO output (V(NO)) rose significantly during exercise, rapidly dropped down following exercise and was similar to resting values after 1 h and 22 h of recovery. The results also showed that C(NO) and V(NO) were significantly lower in the athletes with EIH in comparison with the untrained subjects (V(NO) was 5.32 +/- 0.77 nmol/min versus 3.61 +/- 0.72 nmol/min at rest, 18.52 +/- 1.50 nmol/min versus 15.00 +/- 2.06 nmol/min during heavy exercise, and 5.52 +/- 1.04 nmol/min versus 3.79 +/- 0.76 nmol/min after 22 h recovery, in untrained subjects and EIH athletes, respectively). These findings do not confirm the hypothesis of pulmonary inflammation associated with EIH. However, potential NO epithelial down-regulation may occur and contribute to the development of gas exchange abnormality in some endurance-trained athletes.

Adult↗

PubMed1987

Effects of exercise tolerance, age, and gender on the specificity of radionuclide angiography: sequential ejection fraction analysis during multistage exercise.

We investigated the factors that determine the left ventricular ejection fraction response to exercise in 57 middle-aged, untrained patients with angiographically normal coronary arteries. The ejection fraction was measured by blood pool radionuclide angiography during each stage of exercise. Stepwise regression analysis was applied to 39 variables, and the resulting significant variables were then included in a logistic regression model to determine which of them would predict a normal ejection fraction response. By stepwise regression analysis, the best model (F = 5.6, p = 0.0004) was obtained by combining four variables: achieving 85% of maximal predicted heart rate, peak heart rate, number of exercise stages performed, and resting pulse pressure. Only the latter two variables were significant by logistic regression analysis. The specificity of greater than or equal to 5 ejection fraction unit increase at peak exercise was 42%, 75%, and 100% in patients who exercised one, two, or three stages, respectively. Furthermore, the increase in ejection fraction during each exercise stage was independent of age or gender. Thus the standard criteria of normality during exercise radionuclide angiography have high specificity only when applied to patients with good exercise performance, regardless of age or gender.

Adult↗

PubMed1981

Effects of a prescribed supervised exercise program on mortality and cardiovascular morbidity in patients after myocardial infarction. The National Exercise and Heart Disease Project.

This study enrolled 651 men with myocardial infarction in five participating centers in a randomized 3 year clinical trial of the effects of prescribed supervised exercise. The subjects, aged to 30 to 64 years, were screened for eligibility 2 to 36 months after their qualifying myocardial infarction. The men in the exercise group pursued intensive exercise in the laboratory for 8 weeks and then in a gymnasium for 34 months. The experience of the exercise group was more favorable than that of the control group in most of the comparisons made. The cumulative 3 year total mortality rate was 7.3 percent for the control group and 4.6 percent for the exercise group; the 3 year rate for recurrent myocardial infarction was 7.0 and 5.3 percent, respectively. Mortality rates in the two groups did not differ significantly, but the data were consistent with an assumption of substantial benefit from exercise. Adjustment for small differences in baseline variables by multivariate methods did not materially alter the estimate of effect of exercise. Certain subgroups showed a greater benefit from exercise.

Adult↗

PubMed1983

Incremental value of clinical assessment, supine exercise electrocardiography, and biplane exercise radionuclide ventriculography in the prediction of coronary artery disease in men with chest pain.

The incremental value of clinical assessment, exercise electrocardiography (ECG) and biplane radionuclide ventriculography (RVG) in the prediction of coronary artery disease (CAD) was assessed in 105 men without myocardial infarction who were undergoing coronary angiography for investigation of chest pain. Independent clinical assessment of chest pain was made prospectively by 2 physicians. Graded supine bicycle exercise testing was symptom-limited. Right anterior oblique ECG-gated first-pass RVG and left anterior oblique ECG-gated equilibrium RVG were performed at rest and exercise. Regional wall motion abnormalities were defined by agreement of 2 of 3 blinded observers. A combined strongly positive exercise ECG response was defined as greater than or equal to 2 mm ST depression or 1.0 to 1.9 mm ST depression with exercise-induced chest pain. A multivariate logistic regression model for the preexercise prediction of CAD was derived from the clinical data and selected 2 variables: chest pain class and cholesterol level. A second model assessed the incremental value of the exercise test in prediction of CAD and found 2 exercise variables that improved prediction: RVG wall motion abnormalities, and a combined strongly positive ECG response. Applying the derived predictive models, 37 of the 58 patients (64%) with preexercise probabilities of 10 to 90% crossed either below the 10% probability threshold or above the 90% threshold and 28 (48%) also moved across the 5 and 95% thresholds. Supine exercise testing with ECG and biplane RVG together, but neither test alone, effectively adds to clinical prediction of CAD. It is most useful in men with atypical chest pain and when the ECG and RVG results are concordant.

Adult↗

PubMed1986

Using exercise respiratory measurements to compare methods of exercise prescription.

Exercise heart rate (HR) ranges based on peak HR, age-predicted maximal HR and peak oxygen consumption were compared to determine which method is most likely to result in an exercise prescription within guidelines determined from exercise respiratory measurements (upper limit--ventilatory threshold; lower limit--50% peak oxygen consumption). Exercise prescriptions based on either 80% peak HR or 70% peak measured oxygen consumption were significantly more likely to be within these guidelines (p less than 0.05) than other criteria tested; there was no significant difference between these 2 methods. Recommended exercise intensity based on 85% peak HR and 80% peak oxygen uptake resulted in a large percentage of patients with a heart rate above the ventilatory threshold (46% and 54%, respectively), whereas target HR derived from 75% peak HR and 60% peak oxygen consumption resulted in many patients with a heart rate below the lower limit (38% and 42%, respectively). Exercise prescription based on predicted maximal HR was of little value, regardless of the percentage used to determine target heart rate. The best methods identified in this study yielded an exercise intensity exceeding ventilatory threshold 15 to 20% of the time. Exercise prescription based on direct assessment of the ventilatory threshold is therefore preferred.

Adult↗

PubMed1990

Relation of quantitative coronary lesion measurements to the development of exercise-induced ischemia assessed by exercise echocardiography.

To assess the relation of quantitative measures of coronary stenoses to the development of exercise-induced regional wall motion abnormalities, 34 patients with isolated, single vessel coronary artery lesions and normal wall motion at rest underwent exercise echocardiography and quantitative angiography on the same day. Although all 11 patients with a visually estimated stenosis greater than or equal to 75% had an ischemic response and 10 (91%) of 11 patients with a less than or equal to 25% visually estimated stenosis had a normal response by exercise echocardiography, among 12 patients with a visually estimated stenosis of 50%, 6 (50%) had an ischemic response and 6 (50%) had a normal exercise echocardiogram. Quantitative measurements of stenosis severity distinguished patients with ischemic (group 1) from normal (group 2) exercise echocardiographic responses as follows: minimal luminal diameter (mm), group 1 1.0 +/- 0.4 versus group 2 1.7 +/- 0.4, p less than 0.0001; minimal cross-sectional area (mm2), group 1 0.9 +/- 0.6 versus group 2 2.5 +/- 1.1, p less than 0.0001; percent diameter stenosis, group 1 68.3 +/- 14.2 versus group 2 42.2 +/- 12.1, p less than 0.0001; and percent area stenosis, group 1 87.5 +/- 7.8 versus group 2 64.8 +/- 15.9, p less than 0.0001. These data validate the utility of exercise echocardiography by demonstrating that 1) coronary stenosis severity measured by quantitative angiography is closely related to wall motion abnormalities detected by exercise echocardiography, and 2) exercise echocardiography can be used as a noninvasive means to assess the physiologic significance of coronary artery lesions.

Adult↗