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Training Heart Failure Patients with Reduced Ejection Fraction Attenuates their Muscle Metaboreflex and Lowers Muscle Sympathetic Nerve Activity at Rest and During Mild Dynamic Exercise
Author(s) -
Notarius Catherine Frances,
Millar Philip J.,
Keir Daniel A.,
Murai Hisa,
Haruki Nobuhiko,
O'Donnell Emma,
Marzolini Susan,
Oh Paul,
Floras John S.
Publication year - 2018
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2018.32.1_supplement.853.18
Subject(s) - medicine , microneurography , cardiology , ejection fraction , heart failure , vo2 max , aerobic exercise , vasodilation , physical exercise , heart rate , blood pressure , baroreflex
We have shown that muscle sympathetic nerve activity (MSNA) is elevated at rest in patients with heart failure due to reduced ejection fraction (HFrEF) and, in contrast to healthy subjects, increases during moderate dynamic 1‐leg exercise. We hypothesized that exercise training in HFrEF may reduce MSNA during both mild and moderate intensity 1‐leg dynamic exercise and static handgrip; attenuate the muscle metaboreflex; and improve skin blood flow. We studied 27 stable, medicated HFrEF patients (6 women; mean age 65 ± 2 SE [range 42 to 80] years; mean left ventricular ejection fraction 30 ± 1% [range 12–40]); of either ischemic (n=18) or non‐ischemic (n=9) etiology, both before and after 6 months of cardiac rehabilitation (aerobic exercise for 45 minutes, 5 times per week at 60–70 % of VO 2peak ); plus 18 healthy, age and sex‐matched, medication‐free volunteers (6 women; mean age 57 ± 2 [range 48 to 72]). Before and after training, we assessed VO 2peak (open‐circuit spirometry); the skin blood flow (SBF) response to reactive hyperemia (laser flowtometry); and fibular MSNA (microneurography) at rest (n=18), during 1‐leg cycling (2 min each unloaded and at 50% of VO 2peak , n=16) and, to assess the muscle metaboreflex, during post‐handgrip ischemia (PHGI) after 2 min of 30% static handgrip (HG). In HFrEF, pre‐training VO 2peak and skin vasodilatation were lower (P<0.001) and resting MSNA higher compared to controls (P=0.01). Exercise training improved VO 2peak by 3.0±1.0 ml·kg −1 ·min −1 (P<0.001) and increased the SBF vasdilatory response in HFrEF to a mean value similar to controls (P=0.78). Relative to pre‐training, resting MSNA decreased by 6.0±2.0 bursts/min (P=0.01, N=18) and 7.3±3.4 burst/100 heartbeats (P=0.04). During 1‐leg cycling, MSNA decreased in control (P=0.01) but increased in HFrEF (P<0.001). Exercise training attenuated MSNA burst frequency and incidence during unloaded (P=0.04) but not loaded cycling (P=0.34). The rise in MSNA burst frequency during HG in HFrEF was unaffected by training, but its elevation during PHGI was abolished (P<0.05). We conclude that the exaggerated metaboreflex of HFrEF is attenuated by exercise training. This may contribute to a lower MSNA during mild but not moderate intensity cycling. Support or Funding Information Supported by Heart and Stroke Foundation of Ontario and Canadian Institutes for Health Research This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .