Maurizio Bussotti

Work-rate affects cardiopulmonary exercise test results in heart failure

Cardiopulmonary exercise test (CPET) is used to evaluate patients with chronic heart failure (HF) usually by means of a personalized ramp exercise protocol. Our aim was to evaluate if exercise duration or ramp rate influences the results.

Lack of improvement of lung diffusing capacity following fluid withdrawal by ultrafiltration in chronic heart failure

OBJECTIVES We sought to investigate the possibility that lung diffusing capacity reduction observed in chronic heart failure is reversible in the short term. BACKGROUND Mechanical properties of the lung usually ameliorate with antifailure treatment including drugs, ultrafiltration and heart transplantation, whereas lung diffusion rarely improves. METHODS We studied the mechanical properties of the lung (pulmonary function tests with determination of alveolar volume, extravascular lung fluids and lung tissue), lung diffusion for carbon monoxide (DLco), including membrane diffusing capacity (Dm), pulmonary capillary blood volume (Vc) and pulmonary hemodynamics, in 28 patients with stable chronic heart failure, before a single session of extracorporeal ultrafiltration (3,973 +/- 2200 ml) and four days thereafter. Lung mechanics and diffusion were also evaluated in 18 normal subjects. RESULTS Vital capacity, forced expiratory volume (1 s) and maximal voluntary ventilation were lower in patients when compared with normal subjects, and increased after ultrafiltration from 2.1 +/- 0.7 to 2.5 +/- 0.7(1)*, 1.7 +/- 0.5 to 2.0 +/- 0.6(1)* and 67 +/- 25 to 79 +/- 26 (1/min)*, respectively (* p < 0.02 vs. pre-ultrafiltration). Post-ultrafiltration alveolar volume was augmented, while lung tissue, body weight (approximately 6 kg), chest X-ray extravascular lung water score and pulmonary vascular pressure were reduced. Heart dimensions (echocardiography) remained unchanged. DLco, Dm and Vc were 29.0 +/- 5.0 ml/min/mm Hg, 47.0 +/- 11.0 ml/min/mm Hg, 102 +/- 20 ml in normal subjects and 17.1 +/- 4.0#, 24.1 +/- 6.5#, 113 +/- 38 and 17.0 +/- 5.0#, 24.8 +/- 7.9#, 100 +/- 39 in patients before and after ultrafiltration, respectively (# = p < 0.01 vs. controls). CONCLUSIONS In chronic heart failure, ultrafiltration improves volumes and mechanical properties of the lung by reducing lung fluids. Diffusion is unaffected by ultrafiltration, suggesting that, in chronic heart failure, the alveolar-capillary membrane abnormalities are fluid-independent.

Lung function with carvedilol and bisoprolol in chronic heart failure: Is β selectivity relevant?

Carvedilol is a β‐blocker with similar affinity for β1‐ and β2 receptors, while bisoprolol has higher β1 affinity. The respiratory system is characterized by β2‐receptor prevalence. Airway β receptors regulate bronchial tone and alveolar β receptors regulate alveolar fluid re‐absorption which influences gas diffusion.

Effects of simulated altitude-induced hypoxia on exercise capacity in patients with chronic heart failure

PURPOSE Patients with stable heart failure often wish to spend time at altitudes above those of their residence. However, it is not known whether they can safely tolerate ascent to high altitudes or what its effects on work capacity may be. SUBJECTS AND METHODS We studied 14 normal subjects and 38 patients with clinically stable heart failure, 12 of whom had normal workload [peak exercise oxygen consumption (VO(2)) greater than 20 mL/min/kg], 14 of whom had slightly diminished workload (peak VO(2) 20 to 15 mL/min/kg), and 12 of whom had markedly diminished workload (peak VO(2) less than 15 mL/min/kg) at baseline. All performed cardiopulmonary exercise tests with inspired oxygen fractions equal to those at 92, 1,000, 1,500, 2,000, and 3,000 m, and maximum achieved work rates (mean +/- SD) were measured. RESULTS All subjects completed the trial; no test was interrupted because of arrhythmia, angina, or ischemia. Maximum work rate decreased in parallel with increasing simulated altitude. The percentage decrease was greater for patients with heart failure and was most marked among those with the lowest workload at baseline. Maximum achieved work rate declined by 3% +/- 4% per 1,000 m in normal subjects, by 5% +/- 3% (P <0.01) in patients with heart failure with normal workload, by 5% +/- 4% (P <0.01) in patients with slightly diminished workload, and by 11% +/- 5% (P <0.01 vs normal subjects and vs the other patients with heart failure) in patients with markedly reduced workload. CONCLUSION Patients with stable heart failure who ascend to higher altitudes should expect to have a reduction in maximum physical activity in proportion to their exercise capacity at sea level.

Carvedilol reduces exercise-induced hyperventilation: A benefit in normoxia and a problem with hypoxia

To evaluate whether carvedilol influences exercise hyperventilation and the ventilatory response to hypoxia in heart failure (HF).

Does lung diffusion impairment affect exercise capacity in patients with heart failure

Objective: To determine whether there is a relation between impairment of lung diffusion and reduced exercise capacity in chronic heart failure. Design: 40 patients with heart failure in stable clinical condition and 40 controls participated in the study. All subjects underwent standard pulmonary function tests plus measurements of resting lung diffusion (carbon monoxide transfer, Tlco), pulmonary capillary volume (Vc), and membrane resistance (Dm), and maximal cardiopulmonary exercise testing. In 20 patients and controls, the following investigations were also done: (1) resting and constant work rate Tlco; (2) maximal cardiopulmonary exercise testing with inspiratory O2 fractions of 0.21 and 0.16; and (3) rest and peak exercise blood gases. The other subjects underwent Tlco, Dm, and Vc measurements during constant work rate exercise. Results: In normoxia, exercise induced reductions of haemoglobin O2 saturation never occurred. With hypoxia, peak exercise uptake (peak V̇o2) decreased from (mean (SD)) 1285 (395) to 1081 (396) ml/min (p < 0.01) in patients, and from 1861 (563) to 1771 (457) ml/min (p < 0.05) in controls. Resting Tlco correlated with peak V̇o2 in heart failure (normoxia < hypoxia). In heart failure patients and normal subjects, Tlco and peak V̇o2 correlated with O2 arterial content at rest and during peak exercise in both normoxia and hypoxia. Tlco, Vc, and Dm increased during exercise. The increase in Tlco was greater in patients who had a smaller reduction of exercise capacity with hypoxia. Alveolar–arterial O2 gradient at peak correlated with exercise capacity in heart failure during normoxia and, to a greater extent, during hypoxia. Conclusions: Lung diffusion impairment is related to exercise capacity in heart failure.

Exercise testing in the clinical management of patients affected by pulmonary arterial hypertension.

Patients affected by pulmonary arterial hypertension (PAH) show a reduced exercise tolerance with early occurrence of dyspnoea and fatigue. The origin of functional capacity limitation is multifactorial and several mechanisms have been proposed, including right heart failure, which leads to a limited increase in cardiac output during exercise, and hyperventilation with a reduced perfusion of properly ventilated alveoli. In addition, abnormalities in arterial blood gases are observed, with the occurrence of hypoxemia and hypocapnia, related to an abnormal ventilation/perfusion match, gas diffusion abnormalities, low mixed venous oxygen saturation and to the development of intra- and extra-pulmonary right-to-left shunts. At present, the 6-minute walking test is the most used method to assess exercise tolerance in PAH; it is also useful to monitor the response to therapy and provides prognostic information. However, the assessment of functional capacity by cardiopulmonary exercise test (CPET) seems to be more complete, because CPET allows for discrimination between the metabolic, cardiovascular and pulmonary components of exercise limitation. Moreover, CPET estimates the severity of disease and assesses patients’ prognosis and response to therapy. In PAH, a typical CPET-response is observed, characterized by a severe reduction in peak VO2, work rate, O2 pulse and anaerobic threshold and by a marked increase in VE/VCO2 slope and in the dead space to tidal volume ratio. However, the use of CPET should be limited to experienced centres. This review will focus on resting lung function and exercise tolerance tests, showing that CPET can provide the physiological explanation of functional limitation in PAH.

Impeded Alveolar-Capillary Gas Transfer With Saline Infusion in Heart Failure

The microvascular pulmonary endothelium barrier is critical in preventing interstitial fluid overflow and deterioration in gas diffusion. The role of endothelium in transporting small solutes in pathological conditions, such as congestive heart failure (CHF), has not been studied. Monitoring of pulmonary gas transfer during saline infusion in CHF was used to probe this issue. Carbon monoxide diffusion (DL(CO)), its membrane diffusion (D(M)) and capillary blood volume (V(C)) subcomponents, and mean right atrial (rap) and mean pulmonary wedge (wpp) pressures after saline or 5% D-glucose solution infusions were compared with baseline in 26 moderate CHF patients. Saline was also tested in 13 healthy controls. In patients, 750 mL of saline lowered DL(CO) (-8%, P<0.01 versus baseline), D(M) (-10%, P<0.01 versus baseline), aldosterone (-29%, P<0.01 versus baseline), renin (-52%, P<0.01 versus baseline), and hematocrit (-6%, P<0.05 versus baseline) and increased V(C) (20%, P<0.01 versus baseline), without changing rap and wpp. Saline at 150 mL produced qualitatively similar results regarding DL(CO) (-5%, P<0.01 versus baseline), D(M) (-7%, P<0.01 versus baseline), V(C) (9%, P<0.01 versus baseline), rap, wpp, aldosterone (-9%, P<0.05 versus baseline), and renin (-14%, P<0.05 versus baseline). Glucose solution (750 mL), on the contrary, increased DL(CO) (5%, P<0.01 versus 750 mL of saline) and D(M) (11%, P<0.01 versus 750 mL of saline) and decreased V(C) (-9, P<0.01 versus 750 mL of saline); aldosterone (-40%), renin (-41%), hematocrit (-3%), rap, and wpp behaved as they did after saline infusion. In controls, responses to both saline amounts were similar to responses in CHF patients regarding aldosterone, renin, hematocrit, rap, and wpp, whereas DL(CO), D(M), and V(C) values tended to rise. Hindrance to gas transfer (reduced DL(CO) and D(M)) with salt infusion in CHF, despite an increase in V(C) and no variations in pulmonary hydrostatic forces, indicates an upregulation in sodium transport from blood to interstitium with interstitial edema. Redistribution of blood from the lungs, facilitating interstitial fluid reabsorption, or sodium uptake from the alveolar lumen by the sodium-glucose cotransport system might underlie the improved alveolar-capillary conductance with glucose.

Circulating Plasma Surfactant Protein Type B as Biological Marker of Alveolar-Capillary Barrier Damage in Chronic Heart Failure

Background—Surfactant protein type B (SPB) is needed for alveolar gas exchange. SPB is increased in the plasma of patients with heart failure (HF), with a concentration that is higher when HF severity is highest. The aim of this study was to evaluate the relationship between plasma SPB and both alveolar-capillary diffusion at rest and ventilation versus carbon dioxide production during exercise. Methods and Results—Eighty patients with chronic HF and 20 healthy controls were evaluated consecutively, but the required quality for procedures was only reached by 71 patients with HF and 19 healthy controls. Each subject underwent pulmonary function measurements, including lung diffusion for carbon monoxide and membrane diffusion capacity, and maximal cardiopulmonary exercise test. Plasma SPB was measured by immunoblotting. In patients with HF, SPB values were higher (4.5 [11.1] versus 1.6 [2.9], P=0.0006, median and 25th to 75th interquartile), whereas lung diffusion for carbon monoxide (19.7±4.5 versus 24.6±6.8 mL/mm Hg per min, P<0.0001, mean±SD) and membrane diffusion capacity (28.9±7.4 versus 38.7±14.8, P<0.0001) were lower. Peak oxygen consumption and ventilation/carbon dioxide production slope were 16.2±4.3 versus 26.8±6.2 mL/kg per min (P<0.0001) and 29.7±5.9 and 24.5±3.2 (P<0.0001) in HF and controls, respectively. In the HF population, univariate analysis showed a significant relationship between plasma SPB and lung diffusion for carbon monoxide, membrane diffusion capacity, peak oxygen consumption, and ventilation/carbon dioxide production slope (P<0.0001 for all). On multivariable logistic regression analysis, membrane diffusion capacity (&bgr;, −0.54; SE, 0.018; P<0.0001), peak oxygen consumption (&bgr;, −0.53; SE, 0.036; P=0.004), and ventilation/carbon dioxide production slope (&bgr;, 0.25; SE, 0.026; P=0.034) were independently associated with SPB. Conclusion—Circulating plasma SPB levels are related to alveolar gas diffusion, overall exercise performance, and efficiency of ventilation showing a link between alveolar-capillary barrier damage, gas exchange abnormalities, and exercise performance in HF.

Exercise tolerance can explain the obesity paradox in patients with systolic heart failure: Data from the MECKI Score Research Group

AIMS Obesity has been found to be protective in heart failure (HF), a finding leading to the concept of an obesity paradox. We hypothesized that a preserved cardiorespiratory fitness in obese HF patients may affect the relationship between survival and body mass index (BMI) and explain the obesity paradox in HF. METHODS AND RESULTS A total of 4623 systolic HF patients (LVEF 31.5 ± 9.5%, BMI 26.2 ± 3.6 kg/m(2) ) were recruited and prospectively followed in 24 Italian HF centres belonging to the MECKI Score Research Group. Besides full clinical examination, patients underwent maximal cardiopulmonary exercise test at study enrolment. Median follow-up was 1113 (553-1803) days. The study population was divided according to BMI (<25, 25-30, >30 to ≤35 kg/m(2) ) and predicted peak oxygen consumption (peak VO2 , <50%, 50-80%, >80%). Study endpoints were all-cause and cardiovascular deaths including urgent cardiac transplant. All-cause and cardiovascular deaths occurred in 951 (28.6%, 57.4 per person-years) and 802 cases (17.4%, 48.4 per 1000 person-years), respectively. In the high BMI groups, several prognostic parameters presented better values [LVEF, peak VO2 , ventilation/carbon dioxide slope, renal function, and haemoglobin (P < 0.01)] compared with the lower BMI groups. Both BMI and peak VO2 were significant positive predictors of longer survival: both higher BMI and peak VO2 groups showed lower mortality (P < 0.001). At multivariable analysis and using a matching procedure (age, gender, LVEF, and peak VO2 ), the protective role of BMI disappeared. CONCLUSION Exercise tolerance affects the relationship between BMI and survival. Cardiorespiratory fitness mitigates the obesity paradox observed in HF patients.