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Prolonged Mean Vo2 Response Time in Systolic Heart Failure.
- Source :
- Circulation: Heart Failure; May2013, Vol. 6 Issue 3, p499-507, 9p
- Publication Year :
- 2013
-
Abstract
- In patients with left ventricular systolic dysfunction (LVSD), the rate at which oxygen uptake (VO<subscript>2</subscript>) increases on initiation of exercise is inadequate to match metabolic demands. To gain mechanistic insights into delayed VO<subscript>2</subscript> kinetics in LVSD, we simultaneously assessed hemodynamic measurements, ventilatory parameters, and peripheral oxygen usage during exercise.Forty-two patients with symptomatic LVSD (age, 59±2 years [mean±SEM]; LV ejection fraction, 30±1%) and 17 controls (LV ejection fraction, 68±1%) underwent maximum upright cycle ergometry cardiopulmonary exercise testing. Hemodynamic monitoring and first-pass radionuclide ventriculography were performed at rest and during exercise. VO<subscript>2</subscript> kinetics were quantified by mean response time (MRT), which was significantly longer in patients with LVSD compared with controls (64±3 versus 45±5 s; P=0.004). In LVSD patients, MRT was associated with higher biventricular filling pressures and reduced cardiac output during early exercise. LVSD patients with MRT ≥60 s, compared with LVSD subjects with MRT <60 s, demonstrated greater impairment in right ventricular-pulmonary vascular function during exercise as evidenced by lower right ventricular ejection fraction (35±2 versus 45±2%; P=0.03), steeper increment in transpulmonary gradient relative to cardiac output (3.7 versus 2.2 mm Hg/L; P<0.001), and increased ventilatory dead-space fraction (17±1 versus 12±2%; P=0.03). In contrast, MRT was not associated with LV ejection fraction (rest, exercise), PaO<subscript>2</subscript>, hemoglobin, or resting pulmonary function test results.Delayed oxygen uptake on initiation of exercise (ie, MRT ≥60 s) in LVSD is closely related to impaired right ventricular-pulmonary vascular function and may represent an important surrogate for inability to augment RV performance during physical activity in patients with heart failure. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 19413289
- Volume :
- 6
- Issue :
- 3
- Database :
- Supplemental Index
- Journal :
- Circulation: Heart Failure
- Publication Type :
- Academic Journal
- Accession number :
- 110241795
- Full Text :
- https://doi.org/10.1161/CIRCHEARTFAILURE.112.000157