tel. Near-maximal fractional oxygen extraction by active skeletal muscle in patients with chronic heart failure. J Appl Physiol 88: 2138-2142, 2000.-Systemic oxygen uptake and deep femoral vein oxygen content were determined at peak exercise in 53 patients with chronic heart failure with impaired systolic function (mean left ventricular ejection fraction 0.18; n ϭ 41) or preserved systolic function (mean left ventricular ejection fraction 0.70; n ϭ 12) and in 6 agematched sedentary normal

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... ts. At peak exercise, deep femoral vein oxygen content in heart failure patients with impaired systolic function and preserved systolic function were similar, both significantly lower than that of normal subjects (2.5 Ϯ 0.1, 2.9 Ϯ 0.2, and 5.0 Ϯ 0.1 ml/100 ml, respectively; P Ͻ 0.05). Deep femoral venous oxygen content was lower in patients with the greater impairment of aerobic capacity, regardless of the underlying systolic function (r ϭ 0.72, P Ͻ 0.01). Fractional oxygen extraction in the skeletal muscle at peak exercise is enhanced in patients with chronic heart failure when compared with normal subjects, in proportion to the degree of aerobic impairment. The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.