Use of cardiopulmonary exercise testing with hemodynamic monitoring in the prognostic assessment of ambulatory patients with chronic heart failure.
(25/6923)
OBJECTIVES: We studied whether direct assessment of the hemodynamic response to exercise could improve the prognostic evaluation of patients with heart failure (HF) and identify those in whom the main cause of the reduced functional capacity is related to extracardiac factors. BACKGROUND: Peak exercise oxygen consumption (VO2) is one of the main prognostic variables in patients with HF, but it is influenced also by many extracardiac factors. METHODS: Bicycle cardiopulmonary exercise testing with hemodynamic monitoring was performed, in addition to clinical evaluation and radionuclide ventriculography, in 219 consecutive patients with chronic HF (left ventricular ejection fraction, 22 +/- 7%; peak VO2, 14.2 +/- 4.4 ml/kg/min). RESULTS: During a follow-up of 19 +/- 25 months, 32 patients died and 6 underwent urgent transplantation with a 71% cumulative major event-free 2-year survival. Peak exercise stroke work index (SWI) was the most powerful prognostic variable selected by Cox multivariate analysis, followed by serum sodium and left ventricular ejection fraction, for one-year survival, and peak VO2 and serum sodium for two-year survival. Two-year survival was 54% in the patients with peak exercise SWI < or = 30 g x m/m2 versus 91% in those with a SWI >30 g x m/m2 (p < 0.0001). A significant percentage of patients (41%) had a normal cardiac output response to exercise with an excellent two-year survival (87% vs. 58% in the others) despite a relatively low peak VO2 (15.1 +/- 4.7 ml/kg/min). CONCLUSIONS: Direct assessment of exercise hemodynamics in patients with HF provides additive independent prognostic information, compared to traditional noninvasive data. (+info)
Apoptosis in skeletal myocytes of patients with chronic heart failure is associated with exercise intolerance.
(26/6923)
OBJECTIVES: The purpose of the study was to investigate if apoptosis occurs in skeletal muscle myocytes and its relation to exercise intolerance in patients with chronic heart failure (CHF). BACKGROUND: Intrinsic abnormalities of skeletal muscle frequently limit exercise tolerance in CHF patients. Recently, apoptosis has been detected in cardiac myocytes of patients with CHF, suggesting that apoptosis may contribute to the reduced contractile force. The presence and regulation of apoptosis in skeletal myocytes of patients with CHF remains to be defined. METHODS: Skeletal muscle biopsies (m. vastus lateralis) of 34 CHF patients (New York Heart Association functional class II-III) and eight age-matched healthy control subjects were analyzed by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling for the presence of apoptosis, and by immunohistochemistry and videodensitometrical quantification for inducible nitric oxide synthase (iNOS) and Bcl-2 expression. Maximal oxygen consumption (VO2max) was determined by ergospirometry. RESULTS: Apoptosis was detected in 16/34 (47%) patients with CHF and in none of the healthy subjects. Patients with apoptosis-positive skeletal muscle myocytes exhibited a significantly lower VO2max (12.0 +/- 3.7 vs. 18.2 +/- 4.4 ml/kg/min; p = 0.0005), a higher iNOS expression (6.8 +/- 3.6 vs. 3.7 +/- 2.6% iNOS-positive stained tissue area; p = 0.015) and a lower Bcl-2 expression (1.0 +/- 0.3 vs. 1.4 +/- 0.4% Bcl-2-positive tissue area; p = 0.03) as compared with patients with apoptosis-negative biopsies. CONCLUSIONS: These results indicate that apoptosis is frequently found in skeletal muscle obtained from CHF patients, which is associated with significant impairment of functional work capacity. In skeletal muscle of these patients, iNOS and Bcl-2 are possibly involved in the regulation of apoptosis. (+info)
Enhanced exercise-induced hyperkalemia in patients with syndrome X.
(27/6923)
OBJECTIVES: The purpose of this study was to determine whether patients with syndrome X have altered potassium metabolism. BACKGROUND: Patients with syndrome X have angina pectoris and exercise induced ST segment depression on the electrocardiogram despite normal coronary angiograms. Increasing evidence suggests that myocardial ischemia is uncommon in these patients. Altered potassium metabolism causing interstitial potassium accumulation in the myocardium may be an alternative mechanism for chest pain and ST segment depression in syndrome X. METHODS: We compared the magnitude of exercise-induced hyperkalemia in 16 patients with syndrome X (12 female and four male, mean +/- SD age 53 +/- 6 years) and 15 matched healthy control subjects. The participants underwent a bicycle test at a fixed load of 75 W for 10 min, and blood samples were taken for analysis of potassium, catecholamines and lactate before, during and in the recovery period after exercise. In five patients with syndrome X, the test was repeated during alpha1 adrenoceptor blockade. RESULTS: Baseline concentrations of serum potassium, plasma catecholamines and plasma lactate were similar in patients and control subjects. The rate of exercise-induced increment of serum potassium was increased in the patients (70 +/- 29 vs. 30 +/- 21 micromol/liter/min in control subjects, p < 0.001). Six patients, who stopped before 10 min of exercise, showed very rapid increments in serum potassium concentration. Compared to the control subjects, patients also demonstrated larger increments in rate-pressure product, plasma norepinephrine and lactate concentrations during exercise. The rate of serum potassium increment correlated with the rate of plasma norepinephrine increment in the patients (r = 0.63, p < 0.02), but not in the control subjects (r = 0.01, p = 0.97). Blockade of alpha1 adrenoceptors decreased systolic blood pressure at baseline, but did not influence the increment of serum potassium, plasma catecholamines and lactate. CONCLUSIONS: Patients with syndrome X have enhanced exercise induced hyperkalemia in parallel with augmented increases of circulating norepinephrine and lactate. The prevailing mechanisms behind the abnormal potassium handling comprise sources distinct from alpha1-adrenoceptor activation. (+info)
Changes in cardiorespiratory fitness, psychological wellbeing, quality of life, and vocational status following a 12 month cardiac exercise rehabilitation programme.
(28/6923)
OBJECTIVE: To examine and evaluate improvements in cardiorespiratory fitness, psychological wellbeing, quality of life, and vocational status in postmyocardial infarction patients during and after a comprehensive 12 month exercise rehabilitation programme. SUBJECTS: The sample population comprised 124 patients with a clinical diagnosis of myocardial infarction (122 men and two women). INTERVENTIONS: 62 patients were randomly allocated to a regular weekly aerobic training programme, three times a week for 12 months, and compared with 62 matched controls who did not receive any formal exercise training. A five year follow up questionnaire/interview was subsequently conducted on this population to determine selected vocational/lifestyle changes. RESULTS: Significant improvements in cardiorespiratory fitness (p < 0.01-0.001), psychological profiles (p < 0.05-0.001), and quality of life scores (p < 0.001) were recorded in the treatment population when compared with their matched controls. Although there were no significant differences in mortality, a larger percentage of the regular exercisers resumed full time employment and they returned to work earlier than the controls. Controls took lighter jobs, lost more time from work, and suffered more non-fatal reinfarctions (p < 0.05-0.01). CONCLUSIONS: Regularly supervised and prolonged aerobic exercise training improves cardiorespiratory fitness, psychological status, and quality of life. The trained population also had a reduction in morbidity following myocardial infarction, and significant improvement in vocational status over a five year follow up period. (+info)
The functional significance of chronotropic incompetence during dobutamine stress test.
(29/6923)
OBJECTIVE: To investigate the functional significance of chronotropic incompetence during dobutamine stress echocardiography. PATIENTS AND METHODS: The functional significance of chronotropic incompetence was evaluated during dobutamine stress echocardiography in 512 patients without beta blocker treatment who underwent dobutamine stress echocardiography (up to 40 microg/kg/min) and completed the protocol or reached the target heart rate. Mean (SD) age was 60 (12) years (313 men, 199 women). Chronotropic incompetence was defined as failure to achieve 85% of the maximum exercise heart rate predicted for age and sex (220 - age in men; 200 - age in women) at maximum dobutamine dose. RESULTS: Chronotropic incompetence occurred in 196 patients (38%). Affected patients were significantly younger, more likely to be men (both p << 0.001) and smokers (p < 0.05), had a higher prevalence of previous myocardial infarction (p < 0.005) and resting wall motion abnormalities (p < 0. 05), and had a lower resting heart rate (p << 0.001) and systolic blood pressure (p << 0.001) than patients without chronotropic incompetence, but there was no difference in the overall prevalence of ischaemia and significant coronary artery disease. By multivariate analysis, independent predictors of chronotropic incompetence were a lower resting heart rate (p << 0.001), younger age (p << 0.001), and male sex (p << 0.001). CONCLUSIONS: The relations among sex, age, and chronotropic incompetence show the need to titrate the dobutamine dose using specific data based on age and sex related heart rate responses to dobutamine rather than to an exercise stress test. Obtaining specific heart rate criteria is necessary to determine whether chronotropic incompetence represents a real failure to achieve a normal response or is the result of applying an inappropriate gold standard. (+info)
Effect of repetitive episodes of exercise induced myocardial ischaemia on left ventricular function in patients with chronic stable angina: evidence for cumulative stunning or ischaemic preconditioning?
(30/6923)
BACKGROUND: Myocardial stunning is known to occur following a single episode of effort angina in patients with coronary artery disease. The effect on left ventricular (LV) function of repeated episodes of ischaemia is unknown. OBJECTIVES: To investigate the effects of repeated episodes of exercise induced ischaemia on LV function in patients with chronic stable angina. METHODS: Patients with significant coronary artery disease and normal LV function underwent two episodes of symptom limited treadmill exercise separated by three different time intervals: either 30 minutes (group A, n = 14); 60 minutes (group B, n = 14); or 240 minutes (group C, n = 14). Quantitative stress echocardiography was performed at repeated intervals between the two exercises and for 240 minutes following the second test. RESULTS: For all groups there was no difference between the degree of ischaemia judged by maximal ST depression during the two tests. All episodes of exercise induced ischaemia produced prolonged abnormalities of LV systolic and diastolic function despite rapid normalisation of haemodynamic and ECG changes. In group A (30 minutes) these abnormalities were less pronounced after the second test than after the first, while in group B (60 minutes) they were more severe and long lasting. In group C (240 minutes) the two tests produced similar abnormalities of LV function. CONCLUSIONS: Prolonged abnormalities of LV function occurred following exercise induced ischaemia with a time course consistent with myocardial stunning. The severity and degree of LV dysfunction caused by a further episode of ischaemia appear to be dependent on the time interval between ischaemic episodes. (+info)
Effect of thoracotomy and lung resection on exercise capacity in patients with lung cancer.
(31/6923)
BACKGROUND: Resection is the treatment of choice for lung cancer, but may cause impaired cardiopulmonary function with an adverse effect on quality of life. Few studies have considered the effects of thoracotomy alone on lung function, and whether the operation itself can impair subsequent exercise capacity. METHODS: Patients being considered for lung resection (n = 106) underwent full static and dynamic pulmonary function testing which was repeated 3-6 months after surgery (n = 53). RESULTS: Thoracotomy alone (n = 13) produced a reduction in forced expiratory volume in one second (FEV1; mean (SE) 2.10 (0.16) versus 1.87 (0.15) l; p<0.05). Wedge resection (n = 13) produced a non-significant reduction in total lung capacity (TLC) only. Lobectomy (n = 14) reduced forced vital capacity (FVC), TLC, and carbon monoxide transfer factor but exercise capacity was unchanged. Only pneumonectomy (n = 13) reduced exercise capacity by 28% (PVO2 23.9 (1.5) versus 17.2 (1.7) ml/min/kg; difference (95% CI) 6.72 (3.15 to 10.28); p<0.01) and three patients changed from a cardiac limitation to exercise before pneumonectomy to pulmonary limitation afterwards. CONCLUSIONS: Neither thoracotomy alone nor limited lung resection has a significant effect on exercise capacity. Only pneumonectomy is associated with impaired exercise performance, and then perhaps not as much as might be expected. (+info)
Comparison of atenolol with propranolol in the treatment of angina pectoris with special reference to once daily administration of atenolol.
(32/6923)
Fourteen patients with angina pectoris completed a double blind trial of atenolol 25 mg, 50 mg, and 100 mg twice daily and propranolol 80 mg thrice daily. In comparison with placebo, all active treatments significantly reduced anginal attacks, consumption of glyceryl trinitrate, resting and exercise heart rate, resting and exercise systolic blood pressure, and significantly prolonged exercise time. There was no significant difference between the effects of propranolol and atenolol. Nine patients completed a further trial comparing atenolol given once or twice daily. Both regimens were effective and there was no significant difference between the reductions in anginal attacks, glyceryl trinitrate consumption, systolic blood pressure, or heart rate. Twenty-four-hour ambulatory electrocardiograms showed that atenolol consistently reduced heart rate throughout the 24-hour period whether given once or twice daily. Atenolol is a potent antianginal agent which, in most patients, is likely to be effective once daily. (+info)