TY - JOUR
T1 - Effect of changes in intrathoracic pressure on cardiac function at rest and during moderate exercise in health and heart failure
AU - Lalande, Sophie
AU - Luoma, Charles E.
AU - Miller, Andrew D.
AU - Johnson, Bruce D.
PY - 2012/2
Y1 - 2012/2
N2 - 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.
AB - 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.
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U2 - 10.1113/expphysiol.2011.061945
DO - 10.1113/expphysiol.2011.061945
M3 - Article
C2 - 22080485
AN - SCOPUS:84856430712
SN - 0958-0670
VL - 97
SP - 248
EP - 256
JO - Experimental physiology
JF - Experimental physiology
IS - 2
ER -