Skeletal muscle metabolic recovery following submaximal exercise in chronic heart failure is limited more by O2 delivery than O2 utilization

Abstract

CHF (chronic heart failure) is associated with a prolonged recovery of skeletal muscle energy stores following submaximal exercise, limiting the ability to perform repetitive daily activities.However, the pathophysiological background of this impairment is not well established. The aim of the present study was to investigate whether muscle metabolic recovery following submaximal exercise in patients with CHF is limited by O2 delivery or O2 utilization. A total of 13 stable CHF patients (New York Heart Association classes II-III) and eight healthy subjects, matched for age and BMI (body mass index), were included. All subjects performed repetitive submaximal dynamic single leg extensions in the supine position. Post-exercise PCr (phosphocreatine) resynthesis was assessed by 31P-MRS (magnetic resonance spectroscopy). NIRS (near-IR spectroscopy) was applied simultaneously, using the rate of decrease in HHb (deoxygenated haemoglobin) as an index of post-exercise muscle re-oxygenation. As expected, PCr recovery was slower in CHF patients than in control subjects (time constant, 47+/-10 compared with 35+/-12 s respectively; P=0.04). HHb recovery kinetics were also prolonged in CHF patients (mean response time, 74+/-41 compared with 44+/-17 s respectively; P=0.04). In the patient group, HHb recovery kinetics were slower than PCr recovery kinetics (P=0.02), whereas no difference existed in the control group(P=0.32). In conclusion, prolonged metabolic recovery in CHF patients is associated with an even slower muscle tissue re-oxygenation, indicating a lower O(2) delivery relative to metabolic demands. Therefore we postulate that the impaired ability to perform repetitive daily activities in these patients depends more on a reduced muscle blood flow than on limitations in O(2) utilization.

Progressive chronic heart failure slows the recovery of microvascular O2pressures after contractions in the rat spinotrapezius muscle

“…5), it does not provide clear insights into tissue that is more representative of human locomotor muscle(s). The present observation that progressive CHF slows the increase in Pmv O 2 during the recovery from contractions in the mixed fiber-type spinotrapezius muscle is consistent with the slowed pulmonary V O 2 (8,9,45), skeletal muscle oxygenation (8,17,24), and PCr (9,24,37,48) recovery kinetics after exercise in CHF patients. The Pmv O 2 asymmetry between the on-and off-transients (MRT off-on ) evident for all groups in the present investigation was expected based on similar observations in young healthy (33), aged (19), and slow-twitch CHF (34) muscle.…”

31P MR Spectroscopy and Computational Modeling Identify a Direct Relation between Pi Content of an Alkaline Compartment in Resting Muscle and Phosphocreatine Resynthesis Kinetics in Active Muscle in Humans

“…Changes in mitochondrial function have been associated with several disorders, including diabetes [21] and chronic heart failure [22]. In vivo mitochondrial capacity in these patients is quantified by the PCr recovery method [23]. In addition, often, muscle biopsy samples are obtained to determine whether a prolonged PCr recovery period is a result of a decreased number of mitochondria or intrinsic mitochondrial dysfunction.…”

Oxyneurography: A new technique for the measurement of nerve oxygenation

“…NIRS was introduced in the 1970s by Jöbsis2 to study cerebral and myocardial blood flow. The technique is currently used in clinical testing to investigate muscle,3 breast tumors,4, 5 cerebral tissue,6, 7 peripheral and cerebrovascular disease,8, 9 and congestive heart failure 10. The advantages of the NIRS technique are its non‐invasiveness, ease of application, and low signal–noise during exercise.…”