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Title: Microvascular oxygen delivery-to-utilization mismatch at the onset of heavy-intensity exercise in optimally treated patients with CHF
Authors: Sperandio, Priscila Abreu [UNIFESP]
Borghi-Silva, Audrey [UNIFESP]
Barroco, Adriano [UNIFESP]
Nery, Luiz Eduardo [UNIFESP]
Almeida, Dirceu R. [UNIFESP]
Neder, J. Alberto [UNIFESP]
Universidade Federal de São Paulo (UNIFESP)
Universidade Federal de São Carlos (UFSCar)
Keywords: blood flow
chronic heart failure
near-infrared spectroscopy
oxygen consumption
Issue Date: 1-Nov-2009
Publisher: Amer Physiological Soc
Citation: American Journal of Physiology-heart and Circulatory Physiology. Bethesda: Amer Physiological Soc, v. 297, n. 5, p. H1720-H1728, 2009.
Abstract: Sperandio PA, Borghi-Silva A, Barroco A, Nery LE, Almeida DR, Neder JA. Microvascular oxygen delivery-to-utilization mismatch at the onset of heavy-intensity exercise in optimally treated patients with CHF. Am J Physiol Heart Circ Physiol 297: H1720-H1728, 2009. First published September 4, 2009; doi:10.1152/ajpheart.00596.2009.-Impaired muscle blood flow at the onset of heavy-intensity exercise may transiently reduce microvascular O(2) pressure and decrease the rate of O(2) 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 beta-blockers) may have improved microvascular O(2) delivery to an extent that intramyocyte metabolic inertia might become the main locus of limitation of O(2) uptake ((V)over dot(O2)) kinetics. We assessed the rate of change of pulmonary (V)over dot(O2) ((V)over dot(O2p)), (estimated) fractional O(2) extraction in the vastus lateralis (similar to Delta[deoxy-Hb + Mb] by near-infrared spectroscopy), and cardiac output ((Q)over dot(T)) 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 (V)over dot(O2p) and (Q)over dot(T) 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(V)over dot(O2)/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 (Q)over dot(T) 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 (V)over dot(O2p) kinetics and tolerance to heavy-intensity exercise in nontrained patients.
ISSN: 0363-6135
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