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PubMed1997

Thoracoscopic lung volume reduction surgery reduces dyspnea and improves exercise capacity in patients with emphysema.

Improved ventilation and exercise capacity follows thoracoscopic lung volume reduction surgery (TLVRS) in patients with severe emphysema. This improvement could be related to changes in inspiratory and expiratory flows following surgery, with consequent improvement in dyspnea indices. Changes in inspiratory/expiratory flows at rest and exercise and their relation to subjective improvement in dyspnea after TLVRS are not well known. We studied 25 patients with severe emphysema who underwent unilateral TLVRS performed in well-defined zones with decreased perfusion in nuclear medicine lung scans. Early follow-up after surgery (4.2 +/- 0.8 mo) showed significant improvements in exercise tolerance: The distance covered over a 6 min walk test increased from 934 +/- 297 to 1,071 +/- 241 ft (p = 0.01). Exercise tolerance using a bicycle ergometer showed increased exercise endurance from 4.43 +/- 1.7 to 5.71 +/- 1.8 min (p < 0.001). The maximum workload tolerated increased from 37 +/- 19 to 52 +/- 21 W (p < 0.01) and VO2 max changed from 9.7 +/- 2 to 11.8 +/- 3 (ml.kg)/min (p < 0.01). This increment was achieved by generating significantly larger minute ventilation (VE), from 24 +/- 11 to 29 +/- 10 L/min, reached through larger tidal volumes (increasing from 951 +/- 330 to 1,145 +/- 367 ml), while maintaining the same maximum respiratory rates. Increased VE was also accompanied by significant increases in both average inspiratory and expiratory flows measured during exercise: from 0.89 +/- 0.41 L/s to 1.06 +/- 0.08 L/s, and from 0.77 +/- 0.37 to 0.90 +/- 0.32 L/s respectively (p < 0.01). The parallel increment in flows resulted in constant T1/Ttot relationship. These functional changes correlated with increased inspiratory flows at rest measured with pulmonary function tests (forced inspiratory volume in one s [FIV1], expiratory flows [FVC, FEV1], and increased maximum voluntary ventilation [MVV]) following the surgically induced reduction in residual volume (RV). These objective changes occurred parallel to improved dyspnea indices. The Baseline Focal Score was 3.36 +/- 1.47 and the Transition Focal Score was 6.12 +/- 0.7. The objectively measured variables at rest that best correlated with subjective improvement in dyspnea were the change in MVV, change in resting arterial PaO2, and change in FEV1 following TLVRS. Exercise variables did not have significant correlation with subjective markers indicating improvement in dyspnea, with the exception of the change in Dyspneic Index [(VE/MVV)100] at maximum exercise.

Adult↗

PubMed1996

Long-term effects of inhaled anticholinergic drug on lung function, dyspnea, and exercise capacity in patients with chronic obstructive pulmonary disease.

To investigate the long-term effects of the inhaled anticholinergic bronchodilator, oxitropium bromide (OTB), on lung function, exercise capacity, and dyspnea in patients with chronic obstructive pulmonary disease (COPD), spirometry and symptom-limited exercise testing before and 1, 6, and 12 months after the regular use of OTB (600 micrograms/day) were performed in 12 patients with the use of OTB (mean age 69.9 +/- 3.1 years; FEV1/FVC 53.3 +/- 1.6%) as well as in 12 control patients who were not treated with OTB (Mean age 68.8 +/- 2.8 years; FEV1/FVC 52.6 +/- 1.9%). The dyspnea was evaluated by the slope of the regression line between Borg scale and oxygen uptake (Vo2) during exercise (Borg scale slope: BSS). At 1, 6, and 12 months after the start of OTB, the forced expiratory volume in one second (FEV1) and the exercise capacity (maximal Vo2) were greater than the pretreatment values and the dyspnea index (BSS) was significantly improved compared with the pretreatment value, while these parameters slightly worsened in the control patients over one year. In conclusion, the chronic use of an inhaled anticholinergic bronchodilator may provide beneficial improvements in expiratory flow rate, exercise performance, and dyspnea in mild to moderate COPD patients over one year.

Administration, Inhalation↗

PubMed2005

Oxygen uptake efficiency slope, a new submaximal parameter in evaluating exercise capacity in chronic heart failure patients.

BACKGROUND: The oxygen uptake efficiency slope (OUES) is a new submaximal parameter which objectively predicts the maximal exercise capacity in children and healthy subjects. However, the usefulness of OUES in adult patients with and without advanced heart failure remains undetermined. The present study investigates the stability and the usefulness of OUES in adult cardiac patients with and without heart failure. METHODS: Forty-five patients with advanced heart failure (group A) and 35 patients with ischemic heart disease but normal left ventricular ejection fraction (group B) performed a maximal exercise test. PeakVO2 and percentage of predicted peakVO2 were markers of maximal exercise capacity, whereas OUES, ventilatory anaerobic threshold (VAT), and slope VE/VCO2 were calculated as parameters of submaximal exercise. RESULTS: Group A patients had lower peakVO2 (P < .001), lower percentage of predicted peakVO2 (P = .001), lower VAT (P < .05), steeper slope VE/VCO2 (P < .001), and lower OUES (P < .02). Within group A, significant differences were found for VAT, slope VE/VCO2, and OUES (all P < .01) between patients with peakVO2 above and below 14 mL O2/kg/min. Of all the submaximal parameters, VAT correlated best with peakVO2 (r =.814, P < .01) followed by OUES/kg (r = .781, P < .01), and slope VE/VCO2 (r = -.492, P < .001). However, VAT could not be determined in 18 (23%) patients. CONCLUSIONS: OUES remains stable over the entire exercise duration and is significantly correlated with peakVO2 in adult cardiac patients with and without impaired LVEF. Therefore, OUES could be helpful to assess exercise performance in advanced heart failure patients unable to perform a maximal exercise test. Further studies are needed to confirm our hypothesis.

Adult↗

PubMed1995

Determinants of exercise capacity in the hypertensive elderly--a study based on the assessment of cardiac reserve by dipyridamole radionuclide angiography.

To evaluate the determinants of exercise capacity in the hypertensive elderly with an assessment of cardiac reserve by dipyridamole radionuclide angiography, 31 elderly subjects (aged 62 to 78 years, 15 hypertensive and 16 normotensive) underwent symptom-limited maximum treadmill exercise with measurement of maximal oxygen consumption along with radionuclide angiography in list mode at rest and after dipyridamole infusion. In the normotensive elderly, maximal oxygen consumption correlated with relative filling volume during the rapid filling period at rest (r = 0.58; p < 0.05), and correlated inversely with the percent change in the peak ejection rate with dipyridamole (r = -0.63; p < 0.01). In contrast, maximal oxygen consumption correlated with atrial contribution at rest (r = 0.69; p < 0.005), and correlated inversely with the percent change in atrial contribution with dipyridamole (r = -0.87; p < 0.0001) in the hypertensive elderly. These results indicate that the mechanisms for maintaining exercise capacity are different in elderly subjects with or without hypertension.

Aged↗

PubMed1986

Effects of iloprost, a stable prostacyclin analog, on exercise capacity and platelet aggregation in stable angina pectoris.

The effects of iloprost, a chemically stable compound with prostacyclin mimetic activity, on exercise capacity and platelet aggregation were assessed in 24 patients with effort angina and proved critical (at least 70% diameter narrowing) coronary artery disease. Upright bicycle ergometer testing (25-W increments every 2 minutes) was performed during drug and placebo infusions using a crossover, randomized, single-blind protocol. Samples for measurements of adenosine diphosphate-induced platelet aggregation in platelet-rich plasma were obtained in all patients before and during the study. Compared with placebo, intravenous iloprost consistently (p less than 0.001) prolonged exercise duration and time to onset of significant (0.1 mV) ST depression. Angina and ST depression occurred at a greater heart rate and rate-pressure product. Benefits were remarkable in some patients (67%) and not in others. Iloprost administration resulted in reduced platelet aggregation at peak exercise in all patients, whether they had consistent or little response to the drug. Thus, iloprost administration may improve exercise capacity in patients with stable exertional angina pectoris. Improvements are independent of changes in the major determinants of myocardial oxygen demand and associated with markedly reduced platelet aggregation, which may account for increased myocardial perfusion in patients with high sensitivity to coronary constriction.

Angina Pectoris↗

PubMed2000

Exercise capacity of thoracotomy patients in the early postoperative period.

OBJECTIVE: We investigated the mechanism involved with the initial drop and subsequent recovery of exercise capacity in the early postoperative period of thoracotomy patients. METHODS: Sixteen patients (13 who had undergone lobectomy, 3 who had undergone pneumonectomy) underwent a routine pulmonary function test (PFT) and a cardiopulmonary exercise test preoperatively, within 14 postoperative days (POD; post-1; mean +/- SD, 9 +/- 2 POD), and after 14 POD (post-2; mean, 26 +/- 12 POD). RESULTS: After surgery on post-1, PFT results of FVC, FEV(1), and maximum ventilatory volume (MVV) significantly decreased. Oxygen uptake (VO(2)) at a venous blood lactate level of 2.2 mmol/L (La-2. 2), which was adopted as the empirical anaerobic threshold, and maximum V O(2) (VO(2)max) decreased significantly to 88.2 +/- 7.9% and 73.1 +/- 15.4% of the preoperative values, respectively. La-2.2 min ventilation (VE)/ MVV and maximum VEmax)/MVV increased significantly from 0.36 +/- 0.08 to 0. 66 +/- 0.20 and from 0.58 +/- 0.14 to 0.80 +/- 0.09, respectively. On post-2, though La-2.2 VO(2) did not change, VO(2)max improved significantly to 81.5 +/- 19.7% of the preoperative values, in association with significant increases in maximal tidal volume and VEmax, which were produced by significant increases in the PFT results. La-2.2 VE/MVV also decreased significantly to 0.49 +/- 0.13, which indicated a sufficient recovery of respiratory reserve at submaximal exercise. CONCLUSIONS: The initial drop of exercise capacity after lung resection seems to be derived from both circulatory and ventilatory limitations. Further, the subsequent recovery within 1 month seems to be produced by an improvement in ventilatory limitation, which was caused by the surgical injury to the chest wall.

Adaptation, Physiological↗

PubMed2004

Longitudinal changes in exercise capacity after stroke.

OBJECTIVE: To determine if stroke patients without specific aerobic training experience a change in the first 6 months after stroke. DESIGN: Descriptive, longitudinal study with repeated measures of exercise capacity at 1, 2, 3, and 6 months after stroke. SETTING: Exercise testing laboratory in a tertiary care hospital. PARTICIPANTS: Consecutive sample of 25 patients (mean age +/- standard deviation, 64.1+/-13.6 y) 1 month after first ischemic stroke. INTERVENTIONS: Not applicable. Main Outcome Measures Peak oxygen consumption (Vo(2)peak) was measured by open-circuit spirometry during maximal effort treadmill walking with 15% body-weight support. RESULTS: Mean Vo(2)peak increased from 14.8+/-5.3 mL x kg(-1). min(-1) at 1 month to 17.3+/-7.0 mL x kg(-1).min(-1) at 6 months after stroke (P=.003) or from 61.7%+/-16% to 71.3%+/-23% of age- and sex-related normative values for sedentary healthy adults (P=.008). CONCLUSIONS: Despite improvements in Vo(2)peak and other indices of cardiovascular training between 1 and 6 months poststroke, substantial limitations in exercise capacity persisted. Further study is needed to determine the extent to which these limitations can be modified through aerobic conditioning.

Age Factors↗

PubMed1995

Role of skeletal muscle metabolism in exercise capacity of patients with myocardial infarction studied by phosphorus-31 nuclear magnetic resonance.

Patients with congestive heart failure reportedly show a poor correlation between cardiac function and exercise tolerance. Recent studies have demonstrated that skeletal muscle is the main factor that limits exercise tolerance. However, the relationship between high-energy phosphate metabolism in skeletal muscle and exercise tolerance has not been well defined. Exercise capacity was assessed in 35 subjects with myocardial infarction in terms of peak oxygen consumption (peak VO2) during treadmill exercise with an analysis of expired gases. On the same day, changes in high-energy phosphates in finger flexor muscle during handgrip exercise were measured by magnetic resonance spectrometry. Phosphocreatine (PCr) utilization and the decrease in pH during handgrip exercise were significantly greater in patients with a poor exercise capacity and their time constant of recovery of PCr was prolonged. The ratios of PCr/Pi (Pi: inorganic phosphate) and PCr/HMPA (HMPA: hexamethylphosphoramide) during exercise and the time constant of recovery of PCr were significantly correlated with peak VO2. These results suggest that skeletal muscle metabolism governs exercise tolerance.

Adult↗

PubMed2006

Peak exercise capacity estimated from incremental shuttle walking test in patients with COPD: a methodological study.

BACKGROUND: In patients with COPD, both laboratory exercise tests and field walking tests are used to assess physical performance. In laboratory tests, peak exercise capacity in watts (W peak) and/or peak oxygen uptake (VO2 peak) are assessed, whereas the performance on walking tests usually is expressed as distance walked. The aim of the study was to investigate the relationship between an incremental shuttle walking test (ISWT) and two laboratory cycle tests in order to assess whether W peak could be estimated from an ISWT. METHODS: Ninety-three patients with moderate or severe COPD performed an ISWT, an incremental cycle test (ICT) to measure W peak and a semi-steady-state cycle test with breath-by-breath gas exchange analysis (CPET) to measure VO2 peak. Routine equations for conversion between cycle tests were used to estimate W peak from measured VO2 peak (CPET). Conversion equation for estimation of W peak from ISWT was found by univariate regression. RESULTS: There was a significant correlation between W peak and distance walked on ISWT x body weight (r = 0.88, p < 0.0001). The agreement between W peak measured by ICT and estimated from ISWT was similar to the agreement between measured W peak (ICT) and W peak estimated from measured VO2 peak by CPET. CONCLUSION: Peak exercise capacity measured by an incremental cycle test could be estimated from an ISWT with similar accuracy as when estimated from peak oxygen uptake in patients with COPD.

Adult↗

PubMedDate not supplied

Disparate effects of improving aerobic exercise capacity and quality of life after cardiac rehabilitation in young and elderly coronary patients.

PURPOSE: Although cardiopulmonary exercise variables predict prognosis, functional capacity, and quality of life (QoL) in patients with coronary artery disease (CAD), these variables have not been assessed fully before and after exercise training in elderly with CAD. Therefore, the purpose of this study was to determine the impact of formal Phase II cardiac rehabilitation and exercise training programs on cardiopulmonary variables and QoL in elderly and younger CAD patients. METHODS: The authors analyzed consecutive patients before and after Phase II cardiac rehabilitation and exercise training programs, and compared exercise cardiopulmonary data and data from validated questionnaires assessing QoL (MOS SF-36) and function in 125 younger patients (< 55 years; mean 48 +/- 6 years) and 57 elderly (> 70 years; mean 78 +/- 3 years). RESULTS: At baseline, elderly patients had lower estimated aerobic exercise capacity (-27%; P < 0.001), peak oxygen consumption (VO2) (-19%; P < 0.01), and anaerobic threshold (-10%; P < 0.05), as well as total function scores (-11%; P < 0.01) and total QoL scores (-5%; P = 0.06). Commonly used prediction equations greatly overestimated aerobic exercise capacity compared with precise measurements using cardiopulmonary testing both before (+23% and +12% in younger and elderly patients, respectively) and after the exercise training programs (+51% and +31% in younger and elderly patients, respectively), and more so in younger compared with older patients. After rehabilitation, the elderly had significant improvements in estimated aerobic exercise capacity (+32%; P < 0.0001), peak VO2 (+13%; P < 0.0001), anaerobic threshold (+11%; P = 0.03), total function scores (+27%; P < 0.0001), and total QoL scores (+20%; P < 0.0001). Although younger patients had greater improvements in estimated aerobic exercise capacity (+44% versus +32%; P = 0.08), peak VO2 (+18% versus +13%; P < 0.01), and anaerobic threshold (+17% versus +11%; P = 0.07), the elderly had statistically greater improvements in both function scores (+27% versus +20%; P = 0.02), and total QoL scores (+20% versus +14%; P = 0.03). CONCLUSIONS: These data confirm the benefits of precisely determining aerobic exercise capacity by cardiopulmonary function, especially to determine the benefits of an exercise training program. In addition, these data using cardiopulmonary exercise tests and validated assessments of quality of life demonstrate the disparate effects of cardiac rehabilitation programs on improvements in aerobic exercise capacity and QoL in young and elderly with CAD.

Adult↗

PubMed2005

Variability in exercise capacity and metabolic response during endurance exercise after a low carbohydrate diet.

The impact of altered blood glucose concentrations on exercise metabolism and performance after a low carbohydrate (CHO) diet was investigated. In random order, 1 wk apart, 9 trained men underwent euglycemic (CI) or placebo (PI) clamps, while performing up to 150 min of cycling at 70% VO2(max), after 48 h on a low CHO diet. The range in improvement in endurance capacity with glucose infusion was large (28 +/- 26%, P < 0.05). Fifty-six percent of subjects in CI failed to complete 150 min of exercise despite maintenance of euglycemia, while only 2 subjects in PI completed 150 min of exercise, despite being hypoglycemic. Total CHO oxidation remained similar between trials. Despite longer exercise times in CI, similar amounts of muscle glycogen were used to PI. Maintenance of euglycemia in the CHO-depleted state might have an ergogenic effect, however, the effect is highly variable between individuals and independent of changes in CHO oxidation.

Adult↗

PubMed2006

Exercise capacity and quadriceps muscle metabolism following training in subjects with COPD.

The aim of the study was to determine whether 16 sessions of exercise training, completed twice weekly, alters exercise capacity, quadriceps muscle metabolism, cross-sectional area (CSA) and strength in subjects with chronic obstructive pulmonary disease (COPD). We studied (a) 10 COPD subjects (mean age+/-sem = 71+/-2 years; FEV1 = 0.99+/-0.1 L) before and after 16 sessions of exercise training, and (b) 10 healthy subjects (age = 68+/-3 years). The COPD subjects underwent an incremental peak exercise test using a cycle ergometer and a 6-min walk test: both improved following exercise training (P < 0.05). Magnetic resonance spectroscopy measurements, in quadriceps muscle, of post-exercise phosphocreatinine (PCr) recovery kinetics were used to assess mitochondrial function in vivo: in the COPD subjects pre-training this was 19+/-8% lower than in healthy subjects (P = 0.03), but a 38+/-12% increase was seen in the COPD subjects following training (P = 0.003). Magnetic resonance imaging was used to assess quadriceps CSA: after training in the COPD subjects this showed a 7+/-2% increase (P = 0.03). Quadriceps strength, measured by the best of five maximum voluntary contractions, also showed a 32+/-11% increase in the COPD subjects (P = 0.007). Sixteen sessions of exercise training, performed twice weekly, increased exercise capacity as well as quadriceps mitochondrial capacity, CSA and strength in the subjects with COPD.

Aged↗

PubMed1987

Exercise capacity, energy metabolism, and beta-adrenoceptor blockade. Comparison between a beta 1-selective and a non-selective beta blocker.

The effects of beta 1 and beta 1/2 blockade on exercise capacity were studied in 9 healthy normotensive subjects. Progressive maximal bicycle ergometer tests, followed by an endurance test at 80% of maximal work load, were performed during randomized, double-blind 3 day treatment periods with placebo, atenolol (beta 1) and oxprenolol (beta 1/2). The reduction of maximal work capacity (ca. 10%) was similar with atenolol and oxprenolol, despite a more pronounced maximal heart rate reduction with atenolol (from 175 +/- 2 to 132 +/- 3 beats.min-1) than with oxprenolol (to 138 +/- 2 beats.min-1). Exercise time during the endurance test was reduced from 36 +/- 4 min with placebo to 27 +/- 3 min with atenolol (p less than 0.05) and 24 +/- 3 min with oxprenolol (p less than 0.01) (atenolol vs. oxprenolol: p less than 0.05). During the endurance test, plasma glycerol and non-esterified fatty acid concentrations were reduced with both atenolol and oxprenolol. The glycerol reduction was more pronounced with oxprenolol than with atenolol, plasma NEFA concentrations being similar. Plasma glucose and lactate concentrations were reduced by oxprenolol but not with atenolol. These data show that submaximal exercise capacity at work loads representing similar relative exercise intensities is reduced during non-selective and beta 1-selective beta blockade. This reduction may be related to the effects of beta 1 blockade on energy metabolism, with possibly an additional effect of beta 2 blockade.

Adrenergic beta-Antagonists↗

PubMedDate not supplied

Exercise capacity and immune function in male and female patients with chronic fatigue syndrome (CFS).

Hyperactivition of an unwanted cellular cascade by the immune-related protein RNase L has been linked to reduced exercise capacity in persons with chronic fatigue syndrome (CFS). This investigation compares exercise capacities of CFS patients with deregulation of the RNase L pathway and CFS patients with normal regulation, while controlling for potentially confounding gender effects. Thirty-five male and seventy-one female CFS patients performed graded exercise tests to voluntary exhaustion. Measures of peak VO2, peak heart rate, body mass index, perceived exertion, and respiratory quotient were entered into a two-way factorial analysis with gender and immune status as independent variables. A significant multivariate main effect was found for immune status (p < 0.01), with no gender effect or interaction. Follow-up analyses identified VO2(peak) as contributing most to the difference. These results implicate abnormal immune activity in the pathology of exercise intolerance in CFS and are consistent with a channelopathy involving oxidative stress and nitric oxide-related toxicity.

Adult↗

PubMed2002

Oral beraprost sodium improves exercise capacity and ventilatory efficiency in patients with primary or thromboembolic pulmonary hypertension.

OBJECTIVE: To investigate the effect of beraprost sodium, an orally active prostacyclin analogue, on exercise capacity and ventilatory efficiency in patients with primary pulmonary hypertension and chronic thromboembolic pulmonary hypertension. PATIENTS AND DESIGN: Symptom limited cardiopulmonary exercise testing was performed before and 3 (1) months (mean (SEM)) after beraprost treatment in 30 patients with precapillary pulmonary hypertension (14 with primary pulmonary hypertension and 16 with chronic thromboembolic pulmonary hypertension). RESULTS: Long term treatment with beraprost resulted in significant increases (mean (SEM)) in peak workload (87 (4) W to 97 (5) W, p < 0.001) and peak oxygen consumption (peak VO2, 14.9 (0.7) ml/kg/min to 16.8 (0.7) ml/kg/min, p < 0.001). Beraprost decreased the ventilatory response to carbon dioxide production during exercise (VE-VCO2 slope, 42 (2) to 37 (1), p < 0.001). No significant difference in the responses of these variables to beraprost treatment was observed between patients with primary pulmonary hypertension and chronic thromboembolic pulmonary hypertension. CONCLUSIONS: Oral administration of beraprost sodium may improve exercise capacity and ventilatory efficiency in patients with both primary and chronic thromboembolic pulmonary hypertension.

Administration, Oral↗

PubMed1998

Delayed VO2 kinetics during ramp exercise: a criterion for cardiopulmonary exercise capacity in chronic heart failure.

PURPOSE: Kinetics of VO2 at onset of constant work rate exercise was previously shown to be slowed in patients with chronic heart failure (CHF) compared with that in healthy normals. Because bicycle ergometry with ramp protocol is usually used for exercise testing with CHF patients, it would be of practical importance if it can be shown that a delay in the time interval of linear increase of VO2 (TILIV) to work rate occurs after beginning ramp exercise. Data of central hemodynamics (CHF) and noninvasive cardiopulmonary parameters (CHF, normals) should also correlate with VO2 delay time if this parameter is related to cardiopulmonary exercise capacity. METHODS: Fifteen males with CHF (mean +/- SEM: age 52 +/- 2 yr; ejection fraction 32 +/- 4%; peak cardiac index 3.9 +/- 0.3 L x m(-2) x min(-1)) and 28 healthy males (50 +/- 1 yr) were assessed. During ramp bicycle ergometry (3 min unloaded, work rate increments of 12.5 W x min(-1)), VO2 was measured breath by breath. RESULTS: After the onset of ramp exercise, there was a difference in the TILIV between patients and normals (83.7 +/- 3.6 vs 66.8 +/- 2.9 s; P < 0.001). Significant differences between both groups were also found for VO2 at ventilatory threshold (VT) (10.1 +/- 0.1 vs 15.2 +/- 0.7 mL x kg(-1) x min(-1); P < 0.0001), VO2 at VT relative to predicted VT (58 +/- 4 vs 97 +/- 4%; P < 0.0001), peak VO2 (13.2 +/- 1.0 vs 34 +/- 1.4 mL x kg(-1) x min(-1), P < 0.001), and increase of systolic blood pressure (36 +/- 7 vs 71 +/- 5 mm Hg; P < 0.0001). In CHF, the TILIV correlated significantly with peak cardiac index and VO2 at VT (r = -0.71; P < 0.005 each), relative value of VO2/kg at VT (r = -0.61; P < 0.03), peak VO2/kg (r = -0.63; P < 0.01), and increase of systolic blood pressure (r = -0.52; P < 0.02). In the normals only VO2/kg at VT correlated significantly with TILIV (r = -0.41; P < 0.03). In patients, stepwise regression analysis identified three predictors which could explain 79% of the variance of TILIV: VO2/kg at VT (r2 = 0.51), peak cardiac index (r2 = 0.20), and peak VO2/kg (r2 = 0.08). CONCLUSION: TILIV, determined at the onset of ramp exercise, is prolonged in CHF patients compared with that in normals and reflects severity of functional impairment because of reduced cardiac index and aerobic capacity. TILIV can provide information about changes in cardiopulmonary exercise capacity and thus can be used for follow-up and treatment studies in CHF.

Cardiac Output, Low↗

PubMedDate not supplied

Iodine-123 MIBG imaging before treatment of heart failure with carvedilol to predict improvement of left ventricular function and exercise capacity.

BACKGROUND: We examined whether cardiac sympathetic imaging with iodine-123 metaiodobenzylguanidine (MIBG) would predict improvement of left ventricular (LV) function and exercise capacity in patients with heart failure after treatment with carvedilol. METHODS AND RESULTS: Eighteen patients with heart failure and 5 control subjects underwent I-123 MIBG imaging. Heart-to-mediastinum ratios at 20 minutes and 3 hours and myocardial washout rates (WR) were measured. Of the 18 patients, 11 were randomized to receive carvedilol medication, whereas the remaining 7 received a placebo. Only the carvedilol group demonstrated a significant improvement in both heart failure functional class and LV ejection fraction (EF) 1 year after the start of medication. Within the carvedilol group, MIBG WR showed a significant inverse correlation with improvement in LVEF (rho = -0.74, P =.02). The diagnostic accuracy of WR for predicting EF response to carvedilol was 91%. WR also appeared to be inversely related to the peak oxygen consumption rate (rho = -0.65, P =.08), although this did not reach statistical significance. CONCLUSION: I-123 MIBG imaging appears useful in predicting which patients with heart failure are likely to show the most improvement in LV function and exercise capacity after carvedilol treatment. Further studies in this area appear to be warranted.

3-Iodobenzylguanidine↗

PubMed1994

[Cardiopulmonary exercise capacity in VVI stimulation in patients with high grade AV block].

VVI-pacemaker patients with high-grade atrioventricular block were subjected to cardiopulmonary exercise testing. An interindividual comparison was made between patients with intermittent intrinsic rhythm (n = 9) and patients with permanent VVI-stimulation (n = 15). Patients with intermittent sinus rhythm on exercise had no significant increase in exercise capacity as quantified by the O2-uptake at the anaerobic threshold. An intermittent sinus rhythm is of no relevance to therapeutic decisions, such as choosing the appropriate pacing mode. Exercise capacity is determined by multiple, partly peripheral factors.

Adult↗