Document Detail

Supine low-frequency power of heart rate variability reflects baroreflex function, not cardiac sympathetic innervation.
MedLine Citation:
PMID:  19376985     Owner:  NLM     Status:  PubMed-not-MEDLINE    
BACKGROUND: Power spectral analysis of heart rate variability (HRV) has been used to indicate cardiac autonomic function. High-frequency power relates to respiratory sinus arrhythmia and therefore to parasympathetic cardiovagal tone; however, the relationship of low-frequency (LF) power to cardiac sympathetic innervation and function has been controversial. Alternatively, LF power might reflect baro reflexive modulation of autonomic outflows. OBJECTIVE: We studied normal volunteers and chronic autonomic failure syndrome patients with and without loss of cardiac noradrenergic nerves to examine the relationships of LF power with cardiac sympathetic innervation and baroreflex function. METHODS: We compared LF power of HRV in patients with cardiac sympathetic denervation, as indicated by low myocardial concentrations of 6-[(18)F]fluorodopamine-derived radioactivity or low rates of norepinephrine entry into coronary sinus plasma (cardiac norepinephrine spillover) to values in patients with intact innervation, at baseline, during infusion of yohimbine, which increases exocytotic norepinephrine release from sympathetic nerves, or during infusion of tyramine, which increases non-exocytotic release. Baroreflex-cardiovagal slope (BRS) was calculated from the cardiac interbeat interval and systolic pressure during the Valsalva maneuver. Results. LF power was unrelated to myocardial 6-[(18)F]fluorodopamine-derived radioactivity or cardiac norepinephrine spillover. In contrast, the log of LF power correlated positively with the log of BRS (r = 0.72, P < 0.0001). Patients with a low BRS (</=3 msec/mm Hg) had low LF power, regardless of cardiac innervation. Tyramine and yohimbine increased LF power in subjects with normal BRS but not in those with low BRS. BRS at baseline predicted LF responses to tyramine and yohimbine. CONCLUSION: LF power reflects baroreflex function, not cardiac sympathetic innervation.
Jeffrey P Moak; David S Goldstein; Basil A Eldadah; Ahmed Saleem; Courtney Holmes; Sandra Pechnik; Yehonatan Sharabi
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Intramural    
Journal Detail:
Title:  Cleveland Clinic journal of medicine     Volume:  76 Suppl 2     ISSN:  1939-2869     ISO Abbreviation:  Cleve Clin J Med     Publication Date:  2009 Apr 
Date Detail:
Created Date:  2009-04-20     Completed Date:  2009-07-22     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8703441     Medline TA:  Cleve Clin J Med     Country:  United States    
Other Details:
Languages:  eng     Pagination:  S51-9     Citation Subset:  -    
Children's National Medical Center, Washington, DC, USA.
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