Subject(s)
Echocardiography, Doppler , Echocardiography, Stress , Exercise Test , Lung/diagnostic imaging , Mitral Valve Insufficiency/diagnostic imaging , Mitral Valve/diagnostic imaging , Pulmonary Edema/diagnostic imaging , Tricuspid Valve Insufficiency/diagnostic imaging , Tricuspid Valve/diagnostic imaging , Female , Hemodynamics , Humans , Lung/physiopathology , Male , Middle Aged , Mitral Valve/physiopathology , Mitral Valve Insufficiency/complications , Mitral Valve Insufficiency/physiopathology , Predictive Value of Tests , Pulmonary Edema/etiology , Pulmonary Edema/physiopathology , Severity of Illness Index , Tricuspid Valve/physiopathology , Tricuspid Valve Insufficiency/complications , Tricuspid Valve Insufficiency/physiopathologyABSTRACT
PURPOSE: The objective of this study was to investigate the effect of changes in expiratory intrathoracic pressure on stroke volume (SV) at rest and during moderate exercise in patients with heart failure versus healthy individuals. METHODS: SV was obtained by echocardiography during spontaneous breathing and during expiratory loads of 5 and 10 cm H2O produced by a ventilator in 11 patients with heart failure (61 ± yr, ejection fraction: 32 ± 4%, New York Heart Association, 32% ± 4%; NYHA class I-II) and 11 age-matched healthy individuals at rest and during exercise at 60% of aerobic capacity on a semirecumbent cycle ergometer. RESULTS: At rest, expiratory loading did not change HR, SV index (SVI), or cardiac index (CI) in either group. During moderate exercise, expiratory loading increased SVI and CI in patients with heart failure but decreased SVI and CI in healthy individuals. There was a negative correlation between changes in gastric pressure and SVI (r = -0.51, P < 0.05) in healthy individuals, whereas there was a positive correlation between changes in gastric pressure accompanying expiratory loading and CI (r = 0.83, P < 0.01) in patients with heart failure. CONCLUSION: Expiratory loading during moderate exercise elicited increases in SVI and CI in patients with heart failure but decreased SVI and CI in healthy individuals. Improvements in cardiac function during submaximal exercise in patients with heart failure may be caused by a beneficial reduction in left ventricular preload.
Subject(s)
Airway Resistance/physiology , Cardiac Output/physiology , Exercise/physiology , Exhalation/physiology , Heart Failure/physiopathology , Aged , Case-Control Studies , Echocardiography , Exercise Tolerance/physiology , Female , Humans , Male , Middle Aged , Rest/physiology , Stroke Volume/physiology , Ventricular Function, Left/physiology , Work of BreathingABSTRACT
This study investigated the effect of changes in inspiratory intrathoracic pressure on stroke volume at rest and during moderate exercise in patients with heart failure and reduced ejection fraction (HFREF) as well as healthy individuals. Stroke volume was obtained by echocardiography during 2 min of spontaneous breathing (S), two progressive levels of inspiratory unloading (UL1 and UL2) using a ventilator, and two progressive levels of inspiratory loading using resistors in 11 patients with HFREF (61 ± 9 years old; ejection fraction 32 ± 4%; NYHA class I-II) and 11 age-matched healthy individuals at rest and during exercise at 60% of maximal aerobic capacity on a semi-recumbent cycle ergometer. At rest, inspiratory unloading progressively decreased stroke volume index (SVI; S, 35.2 ± 5.4 ml m(-2); UL1, 33.3 ± 5.1 ml m(-2); and UL2, 32.2 ± 4.4 ml m(-2)) in healthy individuals, while it increased SVI (S, 31.4 ± 4.6 ml m(-2); UL1, 32.0 ± 5.9 ml m(-2); and UL2, 34.0 ± 7.2 ml m(-2)) in patients with HFREF (P = 0.04). During moderate exercise, inspiratory unloading decreased SVI in a similar manner (S, 43.9 ± 7.1 ml m(-2); UL1, 40.7 ± 4.7 ml m(-2); and UL2, 39.9 ± 3.7 ml m(-1)) in healthy individuals, while it increased SVI (S, 40.8 ± 6.5 ml m(-2); UL1, 42.8 ± 6.9 ml m(-2); and UL2, 44.1 ± 4. ml m(-2)) in patients with HFREF (P = 0.02). Inspiratory loading did not significantly change SVI at rest or during moderate exercise in both groups. It is concluded that inspiratory unloading improved SVI at rest and during moderate exercise in patients with HFREF, possibly due to a reduction in left ventricular afterload.
