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Am J Physiol Heart Circ Physiol 297: H1720-H1728, 2009. First published September 4, 2009; doi:10.1152/ajpheart.00596.2009
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Microvascular oxygen delivery-to-utilization mismatch at the onset of heavy-intensity exercise in optimally treated patients with CHF

Priscila Abreu Sperandio,1,2 Audrey Borghi-Silva,1,3 Adriano Barroco,1,2 Luiz Eduardo Nery,1 Dirceu R. Almeida,2 and J. Alberto Neder1

1Pulmonary Function and Clinical Exercise Physiology Unit (SEFICE), Division of Respiratory Diseases, Department of Medicine, Federal University of Sao Paulo (UNIFESP), São Paulo; 2Division of Cardiology, Department of Medicine, Federal University of Sao Paulo (UNIFESP), São Paulo; and 3Cardiopulmonary Laboratory, Nucleus of Research in Physical Exercise, Federal University of São Carlos (UFSCar), São Carlos, SP, Brazil

Submitted July 6, 2009 ; accepted in final form September 4, 2009

Impaired muscle blood flow at the onset of heavy-intensity exercise may transiently reduce microvascular O2 pressure and decrease the rate of O2 transfer from capillary to mitochondria in chronic heart failure (CHF). However, advances in the pharmacological treatment of CHF (e.g., angiotensin-converting enzyme inhibitors and third-generation β-blockers) may have improved microvascular O2 delivery to an extent that intramyocyte metabolic inertia might become the main locus of limitation of O2 uptake (VO2) kinetics. We assessed the rate of change of pulmonary VO2 (VO2p), (estimated) fractional O2 extraction in the vastus lateralis (~{Delta}[deoxy-Hb+Mb] by near-infrared spectroscopy), and cardiac output (QT) during high-intensity exercise performed to the limit of tolerance (Tlim) in 10 optimally treated sedentary patients (ejection fraction = 29 ± 8%) and 11 controls. Sluggish VO2p and QT kinetics in patients were significantly related to lower Tlim values (P < 0.05). The dynamics of {Delta}[deoxy-Hb+Mb], however, were faster in patients than controls [mean response time (MRT) = 15.9 ± 2.0 s vs. 19.0 ± 2.9 s; P < 0.05] with a subsequent response "overshoot" being found only in patients (7/10). Moreover, {tau}VO2/MRT-[deoxy-Hb+Mb] ratio was greater in patients (4.69 ± 1.42 s vs. 2.25 ± 0.77 s; P < 0.05) and related to QT kinetics and Tlim (R = 0.89 and –0.78, respectively; P < 0.01). We conclude that despite the advances in the pharmacological treatment of CHF, disturbances in "central" and "peripheral" circulatory adjustments still play a prominent role in limiting VO2p kinetics and tolerance to heavy-intensity exercise in nontrained patients.

blood flow; chronic heart failure; hemodynamics; near-infrared spectroscopy; oxygen consumption


Address for reprint requests and other correspondence: J. A. Neder, Pulmonary Function and Clinical Exercise Physiology Unit (SEFICE); Respiratory Division, Dept. of Medicine; Federal Univ. of São Paulo-Paulista School of Medicine (UNIFESP-EPM), Rua Professor Francisco de Castro 54, Vila Clementino, CEP 04020-050, São Paulo, Brazil (e-mail: albneder{at}pneumo.epm.br).






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