Impairment of ventilatory efficiency in heart failure: prognostic impact

Gas exchange consequences of left heart failure

This review explores the pathophysiology of gas exchange abnormalities arising consequent to either acute or chronic elevation of pulmonary venous pressures. The initial experimental studies of acute pulmonary edema outlined the sequence of events from lymphatic congestion with edema fluid to frank alveolar flooding and its resultant hypoxemia. Clinical studies of acute heart failure (HF) suggested that hypoxemia was associated only with the final stage of alveolar flooding. However, in patients with chronic heart failure and normal oxygenation, hypoxemia could be produced by the administration of potent pulmonary vasodilators, suggesting that hypoxic pulmonary vasoconstriction is an important reflex for these patients. Patients with chronic left HF commonly manifest a reduced diffusing capacity, an abnormality that appears to be a consequence of chronic elevation of left atrial pressure. That reduction in diffusing capacity does not appear to be primarily attributable to increases in lung water but is improved by any sustained treatment that improves overall cardiac function. Patients with heart failure may also manifest an abnormally elevated VE/VCO2 during exercise, and that exercise ventilation abnormality arises as a consequence of both alveolar hyperventilation and elevated physiologic dead space. That elevated exercise VE/VCO2 in an HF patient has proven to be a powerful predictor of an adverse outcome and hence it has received sustained attention in the HF literature. At least three of the classes of drugs used to treat HF will normalize the exercise VE/VCO2, suggesting that the excessive ventilation response may be linked to elevated sympathetic activity.

Pulmonary vascular diseases

Diseases of the pulmonary vasculature are a cause of increased pulmonary vascular resistance (PVR) in pulmonary embolism, chronic thromboembolic pulmonary hypertension (CTEPH), and pulmonary arterial hypertension or decreased PVR in pulmonary arteriovenous malformations on hereditary hemorrhagic telangiectasia, portal hypertension, or cavopulmonary anastomosis. All these conditions are associated with a decrease in both arterial PO2 and PCO2. Gas exchange in pulmonary vascular diseases with increased PVR is characterized by a shift of ventilation and perfusion to high ventilation-perfusion ratios, a mild to moderate increase in perfusion to low ventilation-perfusion ratios, and an increased physiologic dead space. Hypoxemia in these patients is essentially explained by altered ventilation-perfusion matching amplified by a decreased mixed venous PO2 caused by a low cardiac output. Hypocapnia is accounted for by hyperventilation, which is essentially related to an increased chemosensitivity. A cardiac shunt on a patent foramen ovale may be a cause of severe hypoxemia in a proportion of patients with pulmonary hypertension and an increase in right atrial pressure. Gas exchange in pulmonary arteriovenous malformations is characterized by variable degree of pulmonary shunting and/or diffusion-perfusion imbalance. Hypocapnia is caused by an increased ventilation in relation to an increased pulmonary blood flow with direct peripheral chemoreceptor stimulation by shunted mixed venous blood flow.

Functional cardiovascular reserve predicts survival pre-kidney and post-kidney transplantation

Exercise intolerance is an important comorbidity in patients with CKD. Anaerobic threshold (AT) determines the upper limits of aerobic exercise and is a measure of cardiovascular reserve. This study investigated the prognostic capacity of AT on survival in patients with advanced CKD and the effect of kidney transplantation on survival in those with reduced cardiovascular reserve. Using cardiopulmonary exercise testing, cardiovascular reserve was evaluated in 240 patients who were waitlisted for kidney transplantation between 2008 and 2010, and patients were followed for ≤5 years. Survival time was the primary endpoint. Cumulative survival for the entire cohort was 72.6% (24 deaths), with cardiovascular events being the most common cause of death (54.2%). According to Kaplan-Meier estimates, patients with AT <40% of predicted peak VO2 had a significantly reduced 5-year cumulative overall survival rate compared with those with AT ≥40% (P<0.001). Regarding the cohort with AT <40%, patients who underwent kidney transplantation (6 deaths) had significantly better survival compared with nontransplanted patients (17 deaths) (hazard ratio, 4.48; 95% confidence interval, 1.78 to 11.38; P=0.002). Survival did not differ significantly among patients with AT ≥40%, with one death in the nontransplanted group and no deaths in the transplanted group. In summary, this is the first prospective study to demonstrate a significant association of AT, as the objective index of cardiovascular reserve, with survival in patients with advanced CKD. High-risk patients with reduced cardiovascular reserve had a better survival rate after receiving a kidney transplant.

The results of cardiopulmonary exercise test in healthy Korean children and adolescents: single center study

PURPOSE

The cardiopulmonary exercise test (CPET) is an important clinical tool for evaluating exercise capacity and is frequently used to evaluate chronic conditions including congenital heart disease. However, data on the normal CPET values for Korean children and adolescents are lacking. The aim of this study was to provide reference data for CPET variables in children and adolescents.

METHODS

From August 2006 to April 2009, 76 healthy children and adolescents underwent the CPET performed using the modified Bruce protocol. Here, we performed a medical record review to obtain data regarding patient' demographics, medical history, and clinical status.

RESULTS

The peak oxygen uptake (VO2Peak) and metabolic equivalent (METMax) were higher in boys than girls. The respiratory minute volume (VE)/CO2 production (VCO2) slope did not significantly differ between boys and girls. The cardiopulmonary exercise test data did not significantly differ between the boys and girls in younger age group (age, 10 to 14 years). However, in older age group (age, 15 to 19 years), the boys had higher VO2Peak and METMax values and lower VE/VCO2 values than the girls.

CONCLUSION

This study provides reference data for CPET variables in case of children and adolescents and will make it easier to use the CPET for clinical decision-making.

Clinical usefulness of response profiles to rapidly incremental cardiopulmonary exercise testing

The advent of microprocessed "metabolic carts" and rapidly incremental protocols greatly expanded the clinical applications of cardiopulmonary exercise testing (CPET). The response normalcy to CPET is more commonly appreciated at discrete time points, for example, at the estimated lactate threshold and at peak exercise. Analysis of the response profiles of cardiopulmonary responses at submaximal exercise and recovery, however, might show abnormal physiologic functioning which would not be otherwise unraveled. Although this approach has long been advocated as a key element of the investigational strategy, it remains largely neglected in practice. The purpose of this paper, therefore, is to highlight the usefulness of selected submaximal metabolic, ventilatory, and cardiovascular variables in different clinical scenarios and patient populations. Special care is taken to physiologically justify their use to answer pertinent clinical questions and to the technical aspects that should be observed to improve responses' reproducibility and reliability. The most recent evidence in favor of (and against) these variables for diagnosis, impairment evaluation, and prognosis in systemic diseases is also critically discussed.

Management of pulmonary hypertension in left heart disease

Pulmonary hypertension (PH) due to left heart disease is classified as group II according to the Dana Point classification, which includes left ventricular systolic and/or diastolic left heart failure, and left-sided valvular disease. PH due to left heart disease is the most common cause and when present, especially with right ventricular dysfunction, is associated with a worse prognosis. Left heart disease with secondary PH is associated with increased left atrial pressure, which causes a passive increase in pulmonary pressure. Passive PH could be superimposed by an active protective, and in some patients by an ‘out of proportion’, elevated precapillary pulmonary vasoconstriction and vascular remodelling which leads to greater or lesser further increase of the pulmonary artery pressure. In this review, epidemiological and pathophysiologic mechanisms for the development of group II PH are summarized. The conflicting data about the haemodynamic and possible parameters to diagnose passive versus reactive and ‘out of proportion’ PH are presented. The different therapeutic concepts, along with novel treatment strategies, are reviewed in detail and critically discussed regarding their effectiveness and safety.

Comparison of the Seattle heart failure model and cardiopulmonary exercise capacity for prediction of death in patients with chronic ischemic heart failure and intracoronary progenitor cell application

BACKGROUND

Despite many therapeutic advances, the prognosis of patients with chronic heart failure (CHF) remains poor. Therefore, reliable identification of high-risk patients with poor prognosis is of utmost importance. Cardiopulmonary exercise testing (CPET) provides important prognostic information by peak O2 uptake (peak VO2 ), maximal oxygen pulse (O2 Pmax), O2 uptake efficiency slope (OUES), and VE/VCO2 slope (VE/VCO2 ). A different approach for prognostic assessment is the Seattle Heart Failure Model (SHFM), which is based on clinical data and calculates the estimated annual mortality.

HYPOTHESIS

Comparison of the prognostic value of the Seattle Heart Failure Score and cardiopulmonary excercis testing in patients with chronic heart failure.

METHODS

One hundred fifty-seven patients with ischemic heart failure and recent intracoronary progenitor cell application were analyzed for mortality during a follow-up of 4 years. CPET (peak VO2 , O2 Pmax, OUES, VE/VCO2 ) was performed in all patients at baseline. The SHFM score was calculated for every patient, with data obtained at the time of CPET.

RESULTS

During follow-up, 24 patients died (15.2%). Nonsurvivors had significantly worse initial CPET results and a higher SHFM score compared to survivors. Receiver operating characteristics curve analysis of sensitivity and specificity revealed the largest area under the curve value for the SHFM score, followed by VE/VCO2 slope. Kaplan Meier analysis using cutoff points of SHFM and VE/VCO2 slope with highest sensitivity and specificity resulted in significant discrimination of survivors and nonsurvivors. By multivariate analysis, only the SHFM score persisted as independent predictor of mortality in these patients.

CONCLUSIONS

These data indicate superior prognostic power of the SHFM score compared to CPET in patients with chronic ischemic heart failure.

Inspiratory muscle training reduces sympathetic nervous activity and improves inspiratory muscle weakness and quality of life in patients with chronic heart failure: a clinical trial

PURPOSE

To evaluate the effect of inspiratory muscle training (IMT) on cardiac autonomic modulation and on peripheral nerve sympathetic activity in patients with chronic heart failure (CHF).

METHODS

Functional capacity, low-frequency (LF) and high-frequency (HF) components of heart rate variability, muscle sympathetic nerve activity inferred by microneurography, and quality of life were determined in 27 patients with CHF who had been sequentially allocated to 1 of 2 groups: (1) control group (with no intervention) and (2) IMT group. Inspiratory muscle training consisted of respiratory exercises, with inspiratory threshold loading of seven 30-minute sessions per week for a period of 12 weeks, with a monthly increase of 30% in maximal inspiratory pressure (PI(max)) at rest. Multivariate analysis was applied to detect differences between baseline and followup period.

RESULTS

Inspiratory muscle training significantly increased PI(max) (59.2 ± 4.9 vs 87.5 ± 6.5 cmH(2)O, P = .001) and peak oxygen uptake (14.4 ± 0.7 vs 18.9 ± 0.8 mL·kg(-1)·min(-1), P = .002); decreased the peak ventilation (VE)/carbon dioxide production (VCO(2)) ratio (35.8 ± 0.8 vs 32.5 ± 0.4, P = .001) and the VE/VCO(2) slope (37.3 ± 1.1 vs 31.3 ± 1.1, P = .004); increased the HF component (49.3 ± 4.1 vs 58.4 ± 4.2 normalized units, P = .004) and decreased the LF component (50.7 ± 4.1 vs 41.6 ± 4.2 normalized units, P = .001) of heart rate variability; decreased muscle sympathetic nerve activity (37.1 ± 3 vs 29.5 ± 2.3 bursts per minute, P = .001); and improved quality of life. No significant changes were observed in the control group.

CONCLUSION

Home-based IMT represents an important strategy to improve cardiac and peripheral autonomic controls, functional capacity, and quality of life in patients with CHF.

Mechanism of augmented exercise hyperpnea in chronic heart failure and dead space loading

Patients with chronic heart failure (CHF) suffer increased alveolar VD/VT (dead-space-to-tidal-volume ratio), yet they demonstrate augmented pulmonary ventilation such that arterial [Formula: see text] ( [Formula: see text] ) remains remarkably normal from rest to moderate exercise. This paradoxical effect suggests that the control law governing exercise hyperpnea is not merely determined by metabolic CO2 production ( [Formula: see text] ) per se but is responsive to an apparent (real-feel) metabolic CO2 load ( [Formula: see text] ) that also incorporates the adverse effect of physiological VD/VT on pulmonary CO2 elimination. By contrast, healthy individuals subjected to dead space loading also experience augmented ventilation at rest and during exercise as with increased alveolar VD/VT in CHF, but the resultant response is hypercapnic instead of eucapnic, as with CO2 breathing. The ventilatory effects of dead space loading are therefore similar to those of increased alveolar VD/VT and CO2 breathing combined. These observations are consistent with the hypothesis that the increased series VD/VT in dead space loading adds to [Formula: see text] as with increased alveolar VD/VT in CHF, but this is through rebreathing of CO2 in dead space gas thus creating a virtual (illusory) airway CO2 load within each inspiration, as opposed to a true airway CO2 load during CO2 breathing that clogs the mechanism for CO2 elimination through pulmonary ventilation. Thus, the chemosensing mechanism at the respiratory controller may be responsive to putative drive signals mediated by within-breath [Formula: see text] oscillations independent of breath-to-breath fluctuations of the mean [Formula: see text] level. Skeletal muscle afferents feedback, while important for early-phase exercise cardioventilatory dynamics, appears inconsequential for late-phase exercise hyperpnea.

Lungs in heart failure

Lung function abnormalities both at rest and during exercise are frequently observed in patients with chronic heart failure, also in the absence of respiratory disease. Alterations of respiratory mechanics and of gas exchange capacity are strictly related to heart failure. Severe heart failure patients often show a restrictive respiratory pattern, secondary to heart enlargement and increased lung fluids, and impairment of alveolar-capillary gas diffusion, mainly due to an increased resistance to molecular diffusion across the alveolar capillary membrane. Reduced gas diffusion contributes to exercise intolerance and to a worse prognosis. Cardiopulmonary exercise test is considered the “gold standard” when studying the cardiovascular, pulmonary, and metabolic adaptations to exercise in cardiac patients. During exercise, hyperventilation and consequent reduction of ventilation efficiency are often observed in heart failure patients, resulting in an increased slope of ventilation/carbon dioxide (VE/VCO₂) relationship. Ventilatory efficiency is as strong prognostic and an important stratification marker. This paper describes the pulmonary abnormalities at rest and during exercise in the patients with heart failure, highlighting the principal diagnostic tools for evaluation of lungs function, the possible pharmacological interventions, and the parameters that could be useful in prognostic assessment of heart failure patients.

Weight gain after lung reduction surgery is related to improved lung function and ventilatory efficiency

RATIONALE

Lung volume reduction surgery (LVRS) is associated with weight gain in some patients, but the group that gains weight after LVRS and the mechanisms underlying this phenomenon have not been well characterized.

OBJECTIVES

To describe the weight change profiles of LVRS patients enrolled in the National Emphysema Treatment Trial (NETT) and to correlate alterations in lung physiological parameters with changes in weight.

METHODS

We divided 1,077 non-high-risk patients in the NETT into groups according to baseline body mass index (BMI): underweight (<21 kg/m(2)), normal weight (21-25 kg/m(2)), overweight (25-30 kg/m(2)), and obese (>30 kg/m(2)). We compared BMI groups and LVRS and medical groups within each BMI stratum with respect to baseline characteristics and percent change in BMI (%ΔBMI) from baseline. We examined patients with (ΔBMI ≥ 5%) and without (ΔBMI < 5%) significant weight gain at 6 months and assessed changes in lung function and ventilatory efficiency (Ve/Vco(2)).

MEASUREMENTS AND MAIN RESULTS

The percent change in BMI was greater in the LVRS arm than in the medical arm in the underweight and normal weight groups at all follow-up time points, and at 12 and 24 months in the overweight group. In the LVRS group, patients with ΔBMI ≥ 5% at 6 months had greater improvements in FEV(1) (11.53 ± 9.31 vs. 6.58 ± 8.68%; P < 0.0001), FVC (17.51 ± 15.20 vs. 7.55 ± 14.88%; P < 0.0001), residual volume (-66.20 ± 40.26 vs. -47.06 ± 39.87%; P < 0.0001), 6-minute walk distance (38.70 ± 69.57 vs. 7.57 ± 73.37 m; P < 0.0001), maximal expiratory pressures (12.73 ± 49.08 vs. 3.54 ± 32.22; P = 0.0205), and Ve/Vco(2) (-1.58 ± 6.20 vs. 0.22 ± 8.20; P = 0.0306) at 6 months than patients with ΔBMI < 5% at 6 months.

CONCLUSIONS

LVRS leads to weight gain in nonobese patients, which is associated with improvement in lung function, exercise capacity, respiratory muscle strength, and ventilatory efficiency. These physiological changes may be partially responsible for weight gain in patients who undergo LVRS.

Effect of ventricular size and function on exercise performance and the electrocardiogram in repaired tetralogy of Fallot with pure pulmonary regurgitation

Background:

In repaired tetralogy of Fallot (TOF), exercise test parameters like peak oxygen uptake and ventilatory efficiency predict mortality. Studies have also suggested cardiac magnetic resonance (CMR)-derived right ventricular (RV) size threshold values for pulmonary valve replacement in repaired TOF. However, effects of proposed RV size on exercise capacity and morbidity are not known.

Methods:

The relationship between CMR-derived ventricular size, function, and pulmonary regurgitation (PR) and NYHA class, exercise performance, and electrocardiogram (ECG) was studied in patients of repaired TOF with pure PR in a retrospective review of records.

Results:

46 patients (22 females), mean age 14 years (8–30.8), were studied. There was no relationship between CMR-derived ventricular size, function, or PR and exercise test parameters, or NYHA class. RV end systolic and end diastolic volume correlated positively with the degree of PR. QRS duration on ECG correlated positively with RV end-diastolic volume (P < 0.01, r² = 0.34) and PR (P < 0.01, r² = 0.52).

Conclusions:

In repaired TOF and pure PR, there is no correlation between ventricular size or function and exercise performance. RV size increases with increasing PR. Timing of pulmonary valve replacement in TOF with pure PR needs further prospective evaluation for its effect on morbidity and mortality.

A simple new visualization of exercise data discloses pathophysiology and severity of heart failure

Background

The complexity of cardiopulmonary exercise testing data and their displays tends to make assessment of patients, including those with heart failure, time consuming.

Methods and Results

We postulated that a new single display that uses concurrent values of oxygen uptake / ventilation versus carbon dioxide output / ventilation ratios (–versus–), plotted on equal X–Y axes, would better quantify normality and heart failure severity and would clarify pathophysiology. Consecutive –versus– values from rest to recovery were displayed on X–Y axes for patients with Class II and IV heart failure and for healthy subjects without heart failure. The displays revealed distinctive patterns for each group, reflecting sequential changes in cardiac output, arterial and mixed venous O₂ and CO₂ content differences, and ventilation (). On the basis of exercise tests of 417 healthy subjects, reference formulas for highest and , which normally occur during moderate exercise, are presented. Absolute and percent predicted values of highest and were recorded for 10 individuals from each group: Those of healthy subjects were significantly higher than those of patients with Class II heart failure, and those of patients with Class II heart failure were higher than those of patients with Class IV heart failure. These values differentiated heart failure severity better than peak , anaerobic threshold, peak oxygen pulse, and slopes. Resting –versus– values were strikingly low for patients with Class IV heart failure, and with exercise, increased minimally or even decreased. With regard to the pathophysiology of heart failure, high values during milder exercise, previously attributed to ventilatory inefficiency, seem to be caused primarily by reduced cardiac output rather than increased .

Conclusion

–versus– measurements and displays, extractable from future or existing exercise data, separate the 3 groups (healthy subjects, patients with Class II heart failure, and patients with Class IV heart failure) well and confirm the dominant role of low cardiac output rather than excessive in heart failure pathophysiology. (J Am Heart Assoc. 2012;1:e001883 doi: 10.1161/JAHA.112.001883.)

Ventilatory efficiency testing as prognostic value in patients with pulmonary hypertension

BACKGROUND

Increased ventilatory response has been shown to have a high prognostic value in patients with chronic heart failure. Our aim was therefore to determine the ventilatory efficiency in pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension by cardiopulmonary exercise testing (CPET) identifying PH-patients with increased risk for death within 24 months after evaluation.

METHODS

116 patients (age: 64 ± 1 years) with a mean pulmonary arterial pressure of 35 ± 1 mmHg underwent CPET and right heart catheterization. During a follow-up of 24 months, we compared the initial characteristics of survivors (n = 87) with nonsurvivors (n = 29).

RESULTS

Significant differences (p ≤ 0.005) between survivors and nonsurvivors existed in ventilatory equivalents for oxygen (42.1 ± 2.1 versus 56.9 ± 2.6) and for carbon dioxide (Ve/VCO2) (47.5 ± 2.2 versus 64.4 ± 2.3). Patients with peak oxygen uptake ≤ 10.4 ml/min/kg had a 1.5-fold, Ve/VCO2 ≥ 55 a 7.8-fold, alveolar-arterial oxygen difference ≥ 55 mmHg a 2.9-fold, and with Ve/VCO2 slope ≥ 60 a 5.8-fold increased risk of mortality in the next 24 months.

CONCLUSIONS

Our results demonstrate that abnormalities in exercise ventilation powerfully predict outcomes in PH. Consideration should be given to add clinical guidelines to reflect the prognostic importance of ventilatory efficiency parameters in addition to peak VO2.

Changes in exercise capacity in subjects with cardiac asymptomatic hereditary hemochromatosis during a follow-up after 5 yrs

OBJECTIVE

A long-term effect of hereditary hemochromatosis (HH) on aerobic exercise capacity (AEC) has not been well described.

DESIGN

Forty-three HH and 21 volunteer control subjects who were asymptomatic underwent cardiopulmonary exercise testing using the Bruce protocol. AEC was assessed with minute ventilation (V(E)), oxygen uptake (V(O)(2)), and carbon dioxide production (V(CO)(2)) at baseline and at a follow-up assessment after 5 yrs. A paired t test was used for analyses of normality data; otherwise, Wilcoxon's signed rank-sum test was used.

RESULTS

Thirty-three HH subjects and 18 volunteer control subjects returned for a repeat cardiopulmonary exercise testing at the fifth-year follow-up (80% overall return rate). At the fifth-year follow-up, AEC was not different between the two groups. Compared with baseline measurements, exercise time, peak V(O)(2), and the V(E)/V(CO)(2) slope did not differ statistically at the fifth-year follow-up between both groups. Iron depletion through phlebotomy for 5 yrs did not significantly affect AEC in newly diagnosed HH subjects at baseline (n = 14) and cardiac arrhythmias during exercise tended to decrease after 5 yrs of therapy in this group.

CONCLUSIONS

The AEC of asymptomatic HH subjects treated using conventional therapy is not statistically affected by the disease during a 5-yr period.

[Thoracic fluid content - a possible determinant of ventilatory efficiency in patients with heart failure]

Ventilatory efficiency, evaluated by cardiopulmonary exercise testing (CPET), has considerable prognostic value in patients with chronic heart failure (CHF) due to left ventricular systolic dysfunction (LVSD). Its determinants nevertheless remain controversial.

AIM

To investigate the possible correlation between parameters of ventilatory efficiency obtained by CPET and thoracic fluid content (TFC), assessed by thoracic electrical bioimpedance (TEB), in patients with CHF due to LVSD.

METHODS

We studied 120 patients with LVSD and CHF, referred to our laboratory for CPET: 76% male, age 52.1 ± 12.1 years, 37% of ischemic etiology, left ventricular ejection fraction 27.6 ± 7.9%, 83% in sinus rhythm, 96% receiving ACEIs and/or ARBs and 79% beta-blockers, and 20% treated with a cardiac resynchronization device. TEB studies were performed after 15 minutes of rest, prior to symptom-limited treadmill CPET, using the modified Bruce protocol. CPET-derived peak oxygen consumption (pVO(2)), the slope of the relationship between minute ventilation (VE) and carbon dioxide production (VCO(2)), VE/VCO(2) at the anaerobic threshold (AT), and TFC assessed by TEB were considered for analysis.

RESULTS

TFC ranged between 20.6 and 45.8kOhm-1, mean 32.2, SD=5.7, median 32.7, pVO(2) 8.9-40.6 ml/kg/min, mean 21.0, SD 6.2, median 20.2, VE/VCO(2) slope 19.8-60.7, mean 30.7, SD 7.9, median 29.1 and VE/VCO(2) at AT 21-62, mean 33.1, SD 7.5, median 31.5. By linear regression, TFC did not correlate with pVO(2) (r=0.05, p=0.58), but showed correlation with parameters of ventilatory efficiency: r=0.20, p=0.032, r(2)=0.04 for VE/VCO(2) slope and r=0.25, p=0.009, r(2)=0.06 for VE/VCO(2) at AT.

CONCLUSION

TFC correlates with CPET parameters of ventilatory efficiency in patients with CHF due to LVSD, suggesting that it may be one of its determinants.

Lung function and dyspnea in patients with permanent atrial fibrillation

BACKGROUND

Reduced forced expiratory volume in one second (FEV(1)) has been associated with new-onset atrial fibrillation (AF), and AF patients often complain of dyspnea. We hypothesized that patients with permanent AF had reduced lung function compared to subjects in sinus rhythm.

METHODS

The participants were 75year-olds from the general population. FEV(1), forced vital capacity (FVC), maximal voluntary ventilation (MVV), total lung capacity by single breath (TLC(SB)), single-breath diffusing capacity of the lung for carbon monoxide (DLCO(SB)) and exercise testing with peak oxygen uptake (VO(2) peak) were assessed. The slope of minute ventilation over carbon dioxide output defined ventilatory efficiency. The Symptom Checklist-frequency and severity questionnaire assessed dyspnea.

RESULTS

AF patients had significantly higher number (%) of subjects below the 5th percentile of predicted FEV(1) (7 (27) versus 3 (4), p=0.005), FVC (6 (23) versus 2 (3), p=0.006) and TLC(SB) (11 (42) versus 12 (18), p=0.014) compared to control subjects, also after adjustment for smoking and obesity, or if disregarding subjects with chronic heart failure. The dyspnea frequency and severity scores correlated with VO(2) peak (r=-0.6, p<0.01) in AF patients, and in control subjects with % predicted FEV(1), MVV and TLC(SB) (r=-0.3, p<0.05).

CONCLUSION

More patients with permanent AF had lung function below normal range than control subjects in sinus rhythm, irrespective of smoking, obesity or chronic heart failure. Dyspnea, however, was related to exercise capacity rather than to lung function in AF patients.

Recovery of oxygen consumption after maximal exercise in children

PURPOSE

The period of early recovery after exercise is characterized by a rapid payback of the oxygen debt incurred during exercise. The purpose of this study was to test the hypothesis that the oxygen consumption (VO(2)) decline during the first minute of recovery after exercise will be faster in children with a higher peak VO(2).

METHODS

We performed a clinically indicated bicycle exercise test in 203 children, aged 15.5 ± 3.2 yr; 33 had healthy heart/minimal heart disease, 59 had left-sided heart disease, 92 had right-sided heart disease, and 19 had postoperative single ventricle. VO(2) was recorded at peak exercise and at 20, 40, and 60 s of recovery.

RESULTS

Peak VO(2) in the study cohort was 30.1 ± 8.5 mL·kg(-1)·min(-1) and fell to 24.3 ± 6.7, 19.5 ± 4.9, and 15.3 ± 4.0 mL·kg(-1)·min(-1) at 20, 40, and 60 s of recovery, respectively. VO(2) recovery was slower in children with right-sided heart disease and single ventricle compared with the other 2 groups and was faster in younger children, boys, children with a higher peak VO(2), and in those with a lower RER at peak exercise. In the linear regression analysis, the slope of VO(2) decline during the first minute of recovery was most strongly associated with the peak VO(2) (R(2) = 0.786, P < 0.001). The only other variable that added to the explained variance was peak RER (R(2) = 0.796, P = 0.004).

CONCLUSIONS

VO(2) decline during the first minute of recovery after maximum exercise is faster in children with higher peak VO(2). VO(2) recovery may be a useful tool in assessing cardiopulmonary health in children.

Levosimendan improves calcium sensitivity of diaphragm muscle fibres from a rat model of heart failure

BACKGROUND AND PURPOSE

Diaphragm muscle weakness occurs in patients with heart failure (HF) and is associated with exercise intolerance and increased mortality. Reduced sensitivity of diaphragm fibres to calcium contributes to diaphragm weakness in HF. Here we have investigated the ability of the calcium sensitizer levosimendan to restore the reduced calcium sensitivity of diaphragm fibres from rats with HF.

EXPERIMENTAL APPROACH

Coronary artery ligation in rats was used as an animal model for HF. Sham-operated rats served as controls. Fifteen weeks after induction of HF or sham operations animals were killed and muscle fibres were isolated from the diaphragm. Diaphragm fibres were skinned and activated with solutions containing incremental calcium concentrations and 10 µM levosimendan or vehicle (0.02% DMSO). Developed force was measured at each calcium concentration, and force-calcium concentration relationships were plotted.

KEY RESULTS

Calcium sensitivity of force generation was reduced in diaphragm muscle fibres from HF rats, compared with fibres from control rats (P < 0.01). Maximal force generation was ∼25% lower in HF diaphragm fibres than in control fibres (P < 0.05). Levosimendan significantly increased calcium sensitivity of force generation in diaphragm fibres from HF and control rats, without affecting maximal force generation.

CONCLUSIONS AND IMPLICATIONS

Levosimendan enhanced the force generating capacity of diaphragm fibres from HF rats by increasing the sensitivity of force generation to calcium concentration. These results provide strong support for testing the effect of calcium sensitizers on diaphragm muscle weakness in patients with HF.

Physiologic decrease of ventilatory response to exercise in the second decade of life in healthy children

BACKGROUND

Cardiopulmonary exercise testing is increasingly used in children with congenital heart defects. Because of changes related to growth, the interpretation of exercise test results heavily relies on the presence of normative data. There is growing interest in the assessment of the ventilatory response to exercise in children with congenital heart disease, but normative data are lacking.

METHODS

We studied 243 consecutive children (age, 13.2 ± 2.1 years; 128 boys) with maximal cardiopulmonary exercise testing. All children had normal clinical examination and echocardiograms. In all children, the slope of the relationship between minute ventilation and carbon dioxide production (VE/VCO(2) slope) was calculated using both only data until the respiratory compensation point (VE/VCO(2RC)) and using data until peak exercise (VE/VCO(2Peak)).

RESULTS

The exercise test was maximal in all children (peak respiratory exchange ratio, 1.2 ± 0.1). For all the cohorts, VE/VCO(2Peak) slope was 28.2 ± 3.7; and VE/VCO(2RC) slope was 24.5 ± 3.0, whereas peak oxygen uptake was 94.6% ± 14.0% of predicted value. Baseline spirometric function was normal in all children (vital capacity, 100% ± 14% and forced expired volume in the first second 97% ± 13% of predicted). From the age of 10 to 16 years, we observed a progressive decrease in both VE/VCO(2Peak) and VE/VCO(2RC) slopes (-0.833 and -0.705 per each year), with the highest reduction observed in boys. Gender-specific percentiles for both VE/VCO(2Peak) and VE/VCO(2RC) slopes were constructed.

CONCLUSION

Ventilatory response to exercise expressed as VE/VCO(2) slope seems to decrease progressively in the second decade of life. Because of age-related changes, interpretation of VE/VCO(2) slopes in this age range should be based on the reported percentiles rather than on the absolute values.

Peripheral endothelial dysfunction is associated with gas exchange inefficiency in smokers

Aims

To assess the cross-sectional association between exercise capacity, gas exchange efficiency and endothelial function, as measured by flow-mediated dilation (FMD) and nitroglycerin-mediated dilation (NMD) of the brachial artery, in a large-scale population-based survey.

Methods

The study population was comprised of 1416 volunteers 25 to 85 years old. Oxygen uptake at anaerobic threshold (VO₂@AT), peak exercise (peakVO₂) and ventilatory efficiency (VE vs. VCO₂ slope and VE/VCO₂@AT) were assessed on a breath-by-breath basis during incremental symptom-limited cardiopulmonary exercise. FMD and NMD measurements at rest were performed using standardised ultrasound techniques.

Results

Multivariable logistic regression analyses revealed a significant association between FMD and ventilatory efficiency in current smokers but not in ex-smokers or non-smokers. There was no association between FMD and VO₂@AT or peak VO₂. In current smokers, for each one millimetre decrement in FMD, VE/VCO₂@AT improved by -3.6 (95% CI -6.8, -0.4) in the overall population [VE vs. VCO₂ slope -3.9 (-7.1, -0.6)]. These results remained robust after adjusting for all major influencing factors. Neither exercise capacity nor ventilatory efficiency was significantly associated with NMD.

Conclusion

In current smokers, FMD is significantly associated with ventilatory efficiency. This result may be interpreted as a potential clinical link between smoking and early pulmonary vasculopathy due to smoking.

Developing pulmonary vasculopathy in systemic sclerosis, detected with non-invasive cardiopulmonary exercise testing

BACKGROUND

Patients with systemic sclerosis (SSc) may develop exercise intolerance due to musculoskeletal involvement, restrictive lung disease, left ventricular dysfunction, or pulmonary vasculopathy (PV). The latter is particularly important since it may lead to lethal pulmonary arterial hypertension (PAH). We hypothesized that abnormalities during cardiopulmonary exercise testing (CPET) in patients with SSc can identify PV leading to overt PAH.

METHODS

Thirty SSc patients from the Harbor-UCLA Rheumatology clinic, not clinically suspected of having significant pulmonary vascular disease, were referred for this prospective study. Resting pulmonary function and exercise gas exchange were assessed, including peakVO2, anaerobic threshold (AT), heart rate-VO2 relationship (O2-pulse), exercise breathing reserve and parameters of ventilation-perfusion mismatching, as evidenced by elevated ventilatory equivalent for CO2 (VE/VCO2) and reduced end-tidal pCO2 (PETCO2) at the AT.

RESULTS

Gas exchange patterns were abnormal in 16 pts with specific cardiopulmonary disease physiology: Eleven patients had findings consistent with PV, while five had findings consistent with left-ventricular dysfunction (LVD). Although both groups had low peak VO2 and AT, a higher VE/VCO2 at AT and decreasing PETCO2 during early exercise distinguished PV from LVD.

CONCLUSIONS

Previously undiagnosed exercise impairments due to LVD or PV were common in our SSc patients. Cardiopulmonary exercise testing may help to differentiate and detect these disorders early in patients with SSc.

Prediction of severe cardiovascular events by VE/VCO2 slope versus peak VO2 in systolic heart failure: a meta-analysis of the published literature

BACKGROUND

Peak VO2 has traditionally been used for prognostic evaluation in systolic heart failure. However, in the past years, VE/VCO2 slope has been shown to be similar or even superior in many studies. We performed a systematic review and a meta-analysis of diagnostic studies of VE/VCO2 slope to assess its ability to predict cardiovascular events in systolic heart failure.

METHODS

We searched the published literature in PubMed and ISI Web of Science for VE/VCO2 slope in heart failure, and performed a systematic review and a meta-analysis of diagnostic studies in articles fulfilling previously established selection criteria. End points were serious cardiovascular events defined as death or the combined end point of death, ventricular assist device implantation, or heart transplant. A sub-analysis was also performed with those articles providing enough data to compare VE/VCO(2) slope prognostic ability to that of peak VO2.

RESULTS

Four hundred ninety-one articles that are potentially relevant were identified, and 12 studies were selected based on our predefined criteria. No heterogeneity or evidence of publication bias was found. The 12 studies included a total of 2,628 patients with a mean follow-up of 31 months (95% CI 16-46 months). The combined event rate at 1 year was 11.2% (95% CI 7.8%-14.6%). Diagnostic odds ratio and area under the curve for serious cardiovascular events were 5.02 (95% CI 4.06-6.21) and 0.75 (95% CI 0.72-0.78), respectively. Six studies provided sufficient data for VE/VCO2 slope and peak VO2 comparison. Both variables showed similar performance, although VE/VCO(2) did present a trend to superiority.

CONCLUSIONS

In this meta-analysis, VE/VCO2 slope represents a reasonable ability to predict serious cardiovascular events in systolic heart failure, and is at least as effective as peak VO2.

Prognostic usefulness of the functional aerobic reserve in patients with heart failure

BACKGROUND

Peak oxygen consumption derived from cardiopulmonary exercise (CPX) testing provides important prognostic information in patients with heart failure (HF). The oxygen consumption at the ventilatory threshold (VT) has also been shown to be prognostic. However, the VT cannot always be detected in patients with HF. Other variables such as the difference between peak oxygen consumption and oxygen consumption at the VT (termed the functional aerobic reserve [FAR]) may also provide prognostic information. The purpose of this study was to determine the prognostic value of an undetectable VT and FAR.

METHODS

Eight hundred seventy-four patients with chronic, systolic HF (70% male, age 54 ± 14 years, ejection fraction 29% ± 12%) underwent CPX and were tracked for 2 years for major events (death, transplant, and left ventricular assist device implantation).

RESULTS

Patients were divided into 2 subgroups based on whether VT could be detected or not. There were 141 major events during the 2-year follow-up. Kaplan-Meier analysis for the 2 VT subgroups demonstrated worse prognoses for patients with a nondetectable VT versus those with a detectable VT (P < .001). Based on receiver operating characteristic curve analysis (FAR = 0 mlO₂ kg⁻¹ min⁻¹ for patients with undetectable VT), the optimal cut-point for FAR was ≤/>3 mlO₂ kg min⁻¹ (sensitivity/specificity 69%/60%). Cox regression analysis identified the FAR as a significant univariate predictor of risk and was retained in multivariate analysis.

CONCLUSION

In conclusion, these data reveal that an undetectable VT and the FAR during CPX testing can provide useful prognostic information in patients with HF.

Submaximal exercise gas exchange is an important prognostic tool to predict adverse outcomes in heart failure

AIMS

Traditionally, VO(2peak) has been used to determine prognosis in heart failure; however, this measure has limitations. Hence, other exercise and gas exchange parameters measured submaximally, e.g. breathing efficiency (V(E)/VCO(2)), end-tidal CO(2) (P(ET)CO(2)), oxygen uptake efficiency slope (OUES), and circulatory power [ systolic blood pressure (SBP)], have been investigated. The aim of this study was to investigate the prognostic relevance of submaximal exercise gas exchange in heart failure patients. Method and results One hundred and thirty-two consecutive heart failure patients (mean age 56 ± 12 years, ejection fraction 29 ± 11%) performed peak treadmill testing. Gas exchange and haemodynamic variables were measured continuously. Gas exchange data obtained from the first 2 min of exercise and at a respiratory exchange ratio (RER) of 0.9 were the measurements of interest. Over a median follow-up period of 62.4 (range 0-114) months, there were 44 endpoints (death or transplant). Univariate analysis demonstrated submaximal predictors of survival, which included V(E)/VCO(2) slope and ratio, P(ET)CO(2), OUES, and circulatory power (P ≤ 0.01). When these and additional submaximal variables were included together in the multivariable analysis, the strongest submaximal exercise predictive model (C-statistic 0.75) comprised data from the first stage of exercise (V(E) and circulatory power) and at an RER of 0.9 (V(E)/VCO(2) ratio). The inclusion of VO(2 peak) and demographic data, with submaximal data (V(E)/VCO(2) ratio at an RER = 0.9), increased the predictiveness of the model (C-statistic 0.78).

CONCLUSION

Submaximal exercise measures provide useful prognostic information for predicting survival in heart failure. This form of testing is logistically easier, cheaper, and safer for patients compared with maximal exercise.

Omalizumab treatment and exercise capacity in severe asthmatics - results from a pilot study

BACKGROUND

In patients with moderate to severe allergic asthma, clinical effectiveness of omalizumab, an approved anti-IgE-reacting substance, is usually assessed by pulmonary function testing (PFT), symptom scores and physicians judgement.

AIMS

We postulate that cardiopulmonary exercise testing (CPET) may provide an additional option to verify symptomatic changes in patients with allergic asthma.

METHODS

Ten consecutive patients with allergic asthma were treated with omalizumab. Prior to and after 16 weeks of treatment all patients underwent PFT and symptom-limited CPET. Results were compared to 10 asthmatic controls without omalizumab medication. Symptoms were assessed according to investigators judgement (IGETE).

RESULTS

All 20 patients showed a significantly impaired exercise capacity at baseline [peak oxygen uptake (VO(2)) 71 ± 16% predicted]. In patients with omalizumab, peakVO(2) increased from 13.8 (8.4-21.4) to 16.8 (11.2-23.9) ml/kg/min (p < 0.05), VO(2) at anaerobic threshold increased by 22% [9.8 (3.3-15.2) to 12.3 (6.7-14.4) ml/kg/min (p < 0.05)]. There was no improvement in the controls. The increase in VO(2) was significantly correlated to the improvement in symptoms. All patients revealed dynamic hyperinflation under exercise with a decreasing extent with omalizumab treatment.

CONCLUSION

This study suggests that CPET may provide additional and useful tools to assess and verify the individual clinical response to omalizumab treatment. An improvement in exercise capacity can reliably mirror changes in quality of life and IGETE. Patients with omalizumab experience significant improvements in their initially impaired exercise capacity. CPET can be safely accomplished in patients with severe asthma.

Resting measures and physiological responses to exercise for the determination of prognosis in patients with chronic heart failure: useful tools for clinical decision-making

Despite recent advances in the management of chronic heart failure (CHF), the prognosis of many of these patients remains dire. The need for an accurate prognosis in these patients has led to the identification of several indicators purported to represent the impact of the disease. Such indicators often are obtained at rest and are not always accurate at determining the clinical status of CHF patients. As a result, the relationship between prognostic indicators and clinical outcomes is frequently weak. On the other hand, physiological responses to acute exercise may unmask patients with the worst clinical status and identify those at increased risk of poor outcomes. Therefore, the present review appraises the value of several prognostic indicators for patients with CHF collected at rest and in response to exercise. In particular, it contrasts the value and accuracy of predictors of mortality widely used in clinical settings, such as oxygen uptake, ventilatory efficiency, and left ventricular ejection fraction, with new and more direct indicators of ventricular systolic and diastolic function.

[The ventilatory response in chronic heart failure population]

Symptom-limited exercise test with peak oxygen consumption measurement possesses a strong prognostic value in chronic heart failure. This parameter allowing notably the selection of patients for heart transplant. Nevertheless, sub maximal effort and beta blocker therapy tend to limit its prognostic value. The ventilatory response evaluated by the minute ventilation - carbon dioxide production (VE/VCO2) linear regression slope during effort is generally considered to be a significant predictor of mortality and hospitalizations in HF population. An enhanced ventilatory response is correlated with a poorer prognostic. In addition, this parameter is not influenced by the intensity of the effort neither by the betablocker therapy. But, physiological determinants are not clear yet. Aim of our study is to confirm the important place of the (VE/VCO2) slope in HF patient's evaluation.

Effects of beta-blockers on ventilation efficiency in heart failure

BACKGROUND

Hyperventilation and consequent reduction of ventilation (VE) efficiency are frequently observed during exercise in heart failure (HF) patients, resulting in an increased slope of VE/carbon dioxide (VE/Vco(2)) relationship. The latter is an independent predictor of HF prognosis. beta-Blockers improve the prognosis of HF patients. We evaluated the effect on the efficiency of VE of a beta(1)-beta(2) unselective (carvedilol) versus a beta(1) selective (bisoprolol) beta-blocker.

METHODS

We analyzed consecutive maximal cardiopulmonary exercise tests performed on 572 clinically stable HF patients (New York Heart Association class I-III, left ventricle ejection fraction < or =50%) categorized in 3 groups: 81 were not treated with beta-blocker, 304 were treated with carvedilol, and 187 were treated with bisoprolol. Clinical conditions were similar.

RESULTS

The VE/Vco(2) slope was lower in carvedilol- compared with bisoprolol-treated patients (29.7 +/- 0.4 vs 31.6 +/- 0.5, P = .023, peak oxygen consumption adjusted) and with patients not receiving beta-blockers (31.6 +/- 0.7, P = .036). Maximum end-tidal CO(2) pressure during the isocapnic buffering period was higher in patients treated with carvedilol (39.0 +/- 0.3 mm Hg) than with bisoprolol (37.2 +/- 0.4 mm Hg, P < .001) and in patients not receiving beta-blockers (37.2 +/- 0.5 mm Hg, P = .001).

CONCLUSIONS

Reduction of hyperventilation, with improvement of VE efficiency during exercise (reduction of VE/Vco(2) slope and increase of maximum end-tidal CO(2) pressure), is specific to carvedilol (beta(1)-beta(2) unselective blocker) and not to bisoprolol (beta(1)-selective blocker).

Impact of gender on benefits of exercise training on sympathetic nerve activity and muscle blood flow in heart failure

AIMS

We compared the effects of exercise training on neurovascular control and functional capacity in men and women with chronic heart failure (HF).

METHODS AND RESULTS

Forty consecutive HF outpatients from the Heart Institute, University of Sao Paulo, Brazil were divided into the following four groups matched by age: men exercise-trained (n = 12), men untrained (n = 10), women exercise-trained (n = 9), women untrained (n = 9). Maximal exercise capacity was determined from a maximal progressive exercise test on a cycle ergometer. Forearm blood flow was measured by venous occlusion plethysmography. Muscle sympathetic nerve activity (MSNA) was recorded directly using the technique of microneurography. There were no differences between groups in any baseline parameters. Exercise training produced a similar reduction in resting MSNA (P = 0.000002) and forearm vascular resistance (P = 0.0003), in men and women with HF. Peak VO(2) was similarly increased in men and women with HF (P = 0.0003) and VE/VCO(2) slope was significantly decreased in men and women with HF (P = 0.0007). There were no significant changes in left-ventricular ejection fraction in men and women with HF.

CONCLUSION

The benefits of exercise training on neurovascular control and functional capacity in patients with HF are independent of gender.

Oscillatory breathing and exercise gas exchange abnormalities prognosticate early mortality and morbidity in heart failure

OBJECTIVES

The goal of this study was to identify better predictors of early death in patients with chronic left ventricular heart failure (CHF). Potential predictors, derived from cardiopulmonary exercise testing, were compared with other commonly used cardiovascular measurements.

BACKGROUND

The prediction of early death in patients with CHF remains challenging.

METHODS

Five hundred eight patients with CHF due to systolic dysfunction underwent resting cardiovascular measurements, 6-min walking tests, and cardiopulmonary exercise testing. The peak oxygen uptake (.VO(2)), peak oxygen pulse, anaerobic threshold, ratio of ventilation to carbon dioxide output (.VE/.VCO(2)), slope of .VE versus .VCO(2), and presence or absence of a distinctive oscillatory breathing pattern (OB) were ascertained. Outcomes were 6-month mortality and morbidity, the latter a sum of cardiac hospitalizations and deaths.

RESULTS

The single best predictor of mortality was an elevated lowest .VE/.VCO(2) (> or =155% predicted). Adding OB on the basis of stepwise regression (optimal 2-predictor model), the odds ratio for mortality increased from 9.4 to 38.9 (p < 0.001). The slope of .VE versus .VCO(2) slope, peak .VO(2), peak oxygen pulse, and anaerobic threshold combined with OB were also strong predictors. OB also increased the odds ratio 2- to 3-fold for each of these (p < 0.01). Kaplan-Meier survival curves and area under the receiver-operating characteristic curve confirmed that lowest .VE/.VCO(2) and OB were superior. For morbidity, elevated lowest .VE/.VCO(2) or lower peak .VO(2) with OB were the best predictors. No nonexercise measurements discriminated mortality and morbidity.

CONCLUSIONS

Cardiopulmonary exercise testing parameters are powerful prognosticators of early mortality and morbidity in patients with CHF, especially the optimal 2-predictor model of a combination of elevated lowest .VE/.VCO(2) and OB.

Effects of immunoadsorption and subsequent immunoglobulin G substitution on cardiopulmonary exercise capacity in patients with dilated cardiomyopathy

BACKGROUND

Recent data indicate that cardiac antibodies play an active role in the pathogenesis of dilated cardiomyopathy (DCM) and may contribute to cardiac dysfunction in patients with DCM. The present study investigated the influence of immunoadsorption with subsequent immunoglobulin G substitution (IA/IgG) on cardiopulmonary exercise capacity in patients with DCM.

METHODS

Sixty patients with DCM (New York Heart Association II-IV, left ventricular ejection fraction < or =45%) were included in this single-center university hospital-based case-control study. Patients either were treated with IA/IgG (n = 30) or were followed without IA/IgG (n = 30). At baseline and after 3 months, we compared echocardiographic assessment of left ventricular function and spiroergometric exercise parameters.

RESULTS

In contrast to controls, left ventricular ejection fraction improved significantly in the IA/IgG group from 33.0% +/- 1.2% to 40.1% +/- 1.5% (P < .001). In the control group, spiroergometric exercise parameters did not change during follow-up. After 3 months, maximum achieved power increased in the treatment group from 114.2 +/- 7.4 to 141.9 +/- 7.9 W (P = .02). Total exercise time increased in the treatment group from 812 +/- 29 to 919 +/- 30 seconds (P < .05). Peak oxygen uptake (Vo(2)) increased from 17.3 +/- 0.9 to 21.8 +/- 1.0 mL min(-1) kg(-1) after IA/IgG (P < .01). Oxygen pulse (peak Vo(2)/maximum heart rate) increased in the treatment group (10.7 +/- 0.7 vs 13.6 +/- 0.7 mL beat(-1) min(-1), P < .01). The Vo(2) at the gas exchange anaerobic threshold increased after 3 months in the treatment group from 10.3 +/- 0.5 to 13.2 +/- 0.5 mL min(-1) kg(-1) (P < .001). The ventilatory response to exercise (V(E)/Vco(2) slope) decreased after IA/IgG therapy from 32.3 +/- 1.5 to 28.7 +/- 0.9 (P = .02).

CONCLUSIONS

In patients with DCM, IA/IgG therapy may induce improvement in echocardiographic and cardiopulmonary exercise parameters.

Resting lung function in the assessment of the exercise capacity in patients with chronic heart failure

BACKGROUND

Despite the lung involvement in patients with chronic heart failure (CHF), the significance of lung function abnormalities to functional status in these patients is still controversial. We postulated that in patients with CHF, resting lung function assessment may provide information of clinical relevance on exercise capacity, expressed as peak oxygen uptake (VO2) and ventilatory response to CO2 production (VE/VCO2) during a maximal exercise.

METHODS

We studied 49 clinically stable patients with CHF (38 men, age range: 25-78 years) (New York Heart Association class range: I-IV) with left ventricular ejection fraction <40%. Patients with chronic obstructive pulmonary disease were excluded. Patients performed pulmonary function tests and maximal incremental exercise test.

RESULTS

Resting spirometry was related to the exercise capacity (P < 0.05), expressed as peak VO2. By means of receiver operating characteristic curve analysis, the forced expiratory volume at first second (FEV1) cutoff point, which better identified patients with a peak VO2 < or =14 mL/kg/min, was <79% of predicted value (0.79 sensitivity and 0.73 specificity). Resting lung diffusion capacity for carbon monoxide and end-tidal pressure of CO2 (PETCO2) were inversely correlated to VE/VCO2 (P < 0.01). The lung diffusion capacity for carbon monoxide and PETCO2 cutoff points, which better identified patients with VE/VCO2 value >34, were <58% of predicted (0.92 sensitivity and 0.42 specificity) and <33 mm Hg (0.67 sensitivity and 0.92 specificity), respectively.

CONCLUSIONS

In patients with CHF, resting lung function, including spirometry, lung diffusion capacity, and PETCO2, can provide clinically useful information on exercise capacity, by predicting peak VO2 and VE/VCO2 slope. The results of this study highlight the role of resting lung function in the assessment of the functional status of cardiac patients.