Change In Exercise Duration Research Articles

The acute response of left ventricular filling dynamics to intravenous verapamil predicts the changes in exercise tolerance after oral verapamil therapy in patients with hypertrophic cardiomyopathy.

We studied the correlation between changes in left ventricular filling dynamics induced by acute intravenous administration of verapamil and the changes in exercise tolerance induced by oral administration of the agent in 30 patients with hypertrophic cardiomyopathy. Diastolic cardiac function was measured by means of a nuclear stethoscope before and 10 min after intravenous administration of verapamil, 0.15 mg.kg-1 over 2 min. Treadmill exercise tests using a modified Bruce protocol were performed before the initiation of oral verapamil treatment and after 4 weeks of oral therapy at a dose of 320-360 mg.day-1 (mean +/- SD 332 +/- 17 mg.day-1). Peak filling rate (PFR) increased in 21 patients, 18 of whom (86%) also had an increase in exercise duration, PFR showed no increase in nine patients, eight of whom (89%) had no change in exercise duration (sensitivity 95%, specificity 73%, predictive value of the positive result 86%, predictive value of the negative result 89%). Acute changes in time from the beginning of rapid filling to PFR (t-PFR) and in left ventricular end-diastolic volume (EDV) were less useful in predicting improvement in exercise tolerance. In 19 patients the changes in PFR and EDV paralleled. Twelve of the 13 patients (92%) with an increase in both parameters also had an increase in exercise duration, whereas all six in whom these parameters were reduced showed no increase in exercise duration (sensitivity 100%, specificity 86%, predictive value of positive results 92%, and predictive value of negative results 100%).(ABSTRACT TRUNCATED AT 250 WORDS)

The Effect of Physician Advice on Exercise Behavior

Background. Although sedentariness, a prevalent lifestyle, is recognized as a significant risk factor for coronary artery disease and other conditions, little is known about the effectiveness of prevention strategies in the primary care setting. This study examines the impact of brief, exercise advice-giving by family physicians. Methods. During a 2-month baseline period, patients visiting their family physician and who were age 18 or older were queried about their exercise habits and attitudes and whether their physician had discussed exercise. During the following 2-month experimental phase, the same data were gathered, and half the physicians were trained to give brief exercise advice. All patients were followed for 1 month. Changes in exercise duration and frequency were the primary outcome measures. Results. During baseline, a sizable portion of patients were given exercise advice. This was true also of control group patients during the experimental phase, although trained physicians gave advice almost twice as often. A comparison of the patients receiving advice with those not receiving advice revealed significant increases in exercise duration, but not frequency. Patient attitudes were responsive to exercise advice. Conclusion. Members of primary care, adult patient population will increase their duration of physical activity in response to physician advice to exercise.

Predictors of exercise benefit after operative relief of left ventricular outflow obstruction by the myotomy-myectomy procedure in hypertrophic cardiomyopathy

To determine predictors of exercise benefit in patients with hypertrophic cardiomyopathy after operative relief of left ventricular (LV) outflow tract obstruction, 30 patients underwent catheterization and exercise testing before and 6 months after operation, and hemodynamic measurements were obtained. The increase in maximal oxygen consumption (VO 2max) during treadmill exercise testing was chosen as an index of exercise benefit. Univariate analysis showed a significant positive correlation of operative change in VO 2max with preoperative LV end-diastolic and pulmonary arterial wedge pressures, operative change in exercise duration, and operative reductions in LV end-diastolic and pulmonary arterial wedge pressures and resting LV outflow tract gradient, and a significant negative correlation with preoperative VO 2max and percent predicted VO 2max. Multivariate analysis by stepwise linear regression of only significant univariate variables selected only preoperative percent predicted VO 2max, and operative reduction in LV end-diastolic pressure and resting LV outflow tract gradient as significant predictors of postoperative change in VO 2max. Stepwise regression analysis, applied only to preoperative exercise and catheterization hemodynamic variables, selected only preoperative percent predicted VO 2max and preoperative LV end-diastolic pressure as predictors of improvement in exercise capacity. Thus, patients with obstructive hypertrophic cardiomyopathy, after failing medical therapy, are most likely to demonstrate improvement in exercise capacity if preoperative exercise testing demonstrates limited exercise capacity and if surgery achieves reduction in elevated resting LV outflow tract gradients and LV filling pressures.

Effect of Exercise Training on Multiple Respiratory Variables in Patients with Coronary Artery Disease: Correlation with Change in Exercise Capacity

Multiple measurements of pulmonary function were performed during exercise testing in 29 patients with coronary artery disease (CAD) before and after exercise training. Following training, significant increases in oxygen consumption (VO2), carbon dioxide production (VCO2), and peak flow at maximal exercise were seen as compared with pretraining values (p less than .01), but not in any other respiratory variables. Only the peak respiratory exchange ratio (RER) achieved during pretraining exercise testing and peak values of minute ventilation (VT), respiratory rate, and VCO2 during a posttraining exercise test showed significant correlations with the change in maximum VO2 following exercise training (p less than .05). Significant correlations were also found among VT, VCO2, and peak flow at peak exercise following exercise training and the change in exercise duration between pretraining and posttraining stress tests. Of 22 patients evaluated with thallium 201 scintigraphy during their pretraining exercise test, 11 developed ischemic ST depression or a reversible perfusion defect. No significant differences in pulmonary function measurements during exercise testing were seen between patients who developed ischemia and those who did not. However, the change in peak metabolic equivalents (METS) achieved between pretraining and posttraining exercise was significantly greater in patients who developed ischemia (.836 +/- 1.003 versus .091 +/- .481, p less than .05). These results indicate that exercise training in patients with CAD is not associated with significant changes in most measurements of pulmonary function and, with the exception of RER at peak exercise, pretraining measurements do no show a significant correlation with changes in exercise capacity.

Exercise capacity and quality of life in the treatment of heart failure

In a double-blind study comparing two active treatments (digoxin and xamoterol) and placebo in patients with heart failure, improvements in exercise capacity and quality of life were observed in all three groups, with no significant differences. The substantial benefits seen in the placebo group were probably the result of increased attention from the medical and research staff and suggest the therapeutic value of special heart failure clinics. The relationship between exercise and symptomatic/functional status has been unclear. We developed quantitative measures of quality-of-life variables and examined their relationship with exercise capacity. There were significant relationships between change in exercise duration and changes in breathlessness, tiredness, chest pain, walking difficulty, rate of walking, difficulty with daily tasks, speed of daily tasks, mood, and sleeping. This study confirms the validity of measuring change in exercise capacity and demonstrates that specific measurements of quality of life make an important contribution to the evaluation of the treatment of heart failure.

Influence of age on left ventricular performance during exercise in normal Japanese subject: Assessment by radionuclide ventriculography

To assess the effects of age on left ventricular performance, multistage supine ergometer exercise radionuclide ventriculography (RNV) was performed in 92 normal subjects. The subjects ranged in age from 24 to 86 years and were free of cardiopulmonary disease and diabetes. Age-related changes in exercise duration, left ventricular end-diastolic volume (LVEDV), left ventricular end-systolic volume (LVESV), cardiac output (CO) left ventricular ejection fraction (LVEF), left ventricular dv/dt, systolic and diastolic time indexes of dv/dt, and peak systolic pressure/left ventricular end-systolic volume (PSP/LVESV) were analyzed at rest and during the peak exercise stage. Age-related decrease in LVEDV and peak diastolic dv/dt were significant at rest. The time indexes of ECG R to peak systolic dv/dt and time of end-systole to peak diastolic dv/dt also were prolonged with age. Both maximum heart rate and exercise duration were shown to decline with age. No age-related difference was observed in LVESV, LVEF or PSP/LVESV either at rest or during exercise. However, the change of LVEF and LVESV during exercise was less in subjects aged 60 or more. These results indicate decreased left ventricular function during exercise in elderly subjects.

Hemodynamic study of short- and long-term isradipine treatment in patients with chronic ischemic congestive heart failure

The acute hemodynamic effects of isradipine on cardiac performance, at rest and during exercise, were examined in nine male patients aged 37 to 69 years with congestive heart failure due to ischemic heart disease. The effects of 10 mg oral isradipine were maximal after two to three hours with significant decreases in blood pressure as well as in systemic and pulmonary vascular resistances, and an increase in cardiac output. There were no significant changes in heart rate or pulmonary capillary wedge pressure. For the same 50-watt bicycle workload pre- and post-drug, the addition of isradipine was associated with lower systemic and pulmonary vascular resistances (systemic vascular resistance, 805 ± 70 versus 975 ± 70; p <0.01; pulmonary vascular resistance, 144 ± 27 versus 207 ± 35 dynes · sec · cm −5; p <0.01), and lower pulmonary artery pressures ( 54 ± 6 230 ± 3 versus 66 ± 7/27 ± 3 mm Hg; p <0.01 ) during exercise. In a double-blind 12-week trial, body weight decreased during isradipine treatment (71.6 to 68.9 kg; p <0.01), but there were no significant changes in exercise duration, radionuclide ejection fraction, or cardiothoracic ratio, and no serious side effects were encountered. These results suggest that isradipine is worthy of further evaluation in long-term treatment of chronic ischemic congestive heart failure.

Comparative effects of nadolol-digoxin combination therapy and digoxin monotherapy for chronic atrial fibrillation

In some patients with chronic atrial fibrillation, treatment with digitalis alone may fail to produce a satisfactory decrease in heart rate at rest or during exercise or emotional stress. Findings of a few clinical studies suggest that β blockade in combination with digitalis therapy may be of benefit in these patients. In a randomized, double-blind, placebo-controlled, parallel-group, 8-week study of 32 patients with chronic atrial fibrillation, the effects of digoxin therapy alone were compared with a combination of digoxin and nadolol. Criteria for entry into the study included ventricular rate at rest ≥80/min or ≥120/ min with exercise, and serum digoxin levels within the therapeutic range. After digoxin dose titration to produce therapeutic levels, digoxin dosage remained constant throughout the balance of the study. After a 2-week, single-blind placebo lead-in period, patients were randomized to receive either digoxin plus placebo or a combination of digoxin and nadolol. The dose of nadolol/placebo was titrated from 20 to 120 mg daily as tolerated. Twentyfour hour ambulatory electrocardiographic (Holter) recordings, symptom-limited exercise treadmill tests and serum digoxin and nadolol levels were obtained at the end of the single and double-blind treatment periods. Comparing endpoint with baseline, results from Holter recordings showed that patients treated with a combination of digoxin and nadolol had significant (p < 0.001) decreases in 24 hour average (78 ± 4 to 63 ± 3), minimum 1 hour average (54 ± 3 to 47 ± 2) and maximum 1 hour average (123 ± 8 to 97 ± 4) ventricular rate while the corresponding ventricular rate changes in patients receiving digoxin therapy alone were small (average −80 ± 3 to 84 ± 4, minimum −50 ± 3 to 54 ± 2 and maximum −144 ± 5 to 149 ± 6). During exercise testing, patients given combination therapy had significant decreases in peak exercise ventricular rate (p < 0.002) and double-product (p < 0.001) compared with patients given digoxin alone. There were no significant changes in exercise duration in either group. Serum digoxin levels in the combination and digoxin alone groups were 0.75 ± 0.14 and 0.90 ± 0.08 ng/ml at baseline, respectively, and were not altered at the end of the study when values were 0.92 ± 0.13 and 0.80 ± 0.90 ng/ml, respectively. One patient receiving combination therapy was discontinued from the study because of dizziness. In patients with chronic atrial fibrillation, the combination of digoxin and nadolol was well tolerated and more effective than digoxin alone in controlling excessively rapid ventricular rates during exercise and upon ambulatory monitoring.

Placebo-Controlled Study of Lisinopril in Congestive Heart Failure

A double-blind randomised, parallel, placebo-controlled study was performed in patients with congestive heart failure, at 13 centres in 10 countries, to assess the efficacy and safety of lisinopril, a new angiotensin-converting enzyme inhibitor. After a 2-week run-in period, 130 patients receiving digoxin and/or diuretics were randomised to 12 weeks of treatment with lisinopril 5 mg daily (87 patients) or with placebo (43 patients), with an option to increase lisinopril dosage to 10 or 20 mg. Patients treated with lisinopril improved significantly more than placebo-treated patients (p less than 0.05) for all clinical parameters except oedema and paroxysmal nocturnal dyspnoea. Left ventricular ejection fraction rose by 8% in lisinopril patients compared to 2% in the placebo group, while the cardiothoracic ratio and echocardiographic end systolic diameter fell in the lisinopril group (p less than 0.01) but not in the placebo group. Exercise duration was greater in the lisinopril group at all timepoints, and the increase in exercise duration at 12 weeks was greater by more than 2 min in the lisinopril group as compared to the placebo group (p less than 0.01). Changes in clinical and noninvasive parameters such as the New York Heart Association status, were well correlated with changes in exercise duration. Four patients in the lisinopril group and three in the placebo group died in this study, and there were 31 adverse clinical experiences in the 87 lisinopril-treated patients compared to 13 in the 43 placebo-treated patients. We conclude that lisinopril in doses of 2.5-20 mg/day is well tolerated and effective in patients with heart failure who are receiving digitalis and diuretics.

Plasma norepinephrine in exercise-induced ventricular tachycardia

The relation between plasma norepinephrine levels and the occurrence of ventricular tachycardia during exercise testing was prospectively evaluated in 17 patients. Ten patients had reproducible ventricular tachycardia exclusively during exercise or recovery, or both; 7 patients had ventricular tachycardia only during ambulatory electrocardiographic monitoring. The two groups did not differ in age, exercise duration, left ventricular ejection fraction at rest, heart rate throughout the exercise protocol, rest QTc interval, change in QTc interval during exercise, the presence of coronary artery disease or exercise-related myocardial ischemia. Furthermore, there was no difference between groups in plasma norepinephrine levels at rest, peak exercise or in the recovery period. Myocardial ischemia was detectable by thallium perfusion scan in only 2 of the 10 patients with exercise-induced ventricular tachycardia. The 10 patients with exercise-induced ventricular tachycardia underwent repeat exercise testing immediately after maximal intravenous beta-adrenergic blockade with propranolol. Although they had no change in exercise duration, ventricular tachycardia did not occur in 9 of these 10 patients. Plasma norepinephrine levels were significantly decreased compared with levels before beta-adrenergic blockade (p less than 0.0002). Thus, plasma norepinephrine levels do not distinguish patients with reproducible exercise-induced ventricular tachycardia from otherwise comparable patients. Propranolol is highly effective in abolishing this arrhythmia and this effect is associated with decreased norepinephrine levels.