title: Sympathetic rhythmicity in cardiac transplant recipients.
abstract: BACKGROUND
  Variability of R-R interval and muscle sympathetic nerve activity (MSNA) occurs predominantly at a low frequency (LF, +/-0.1 Hz) and a high frequency (HF, +/-0.25 Hz) in normal humans. Increased sympathetic drive in normal humans is associated with an increased LF component of the R-R interval and MSNA. Patients with severe heart failure have high sympathetic activity but decreased or absent LF power of both R-R and MSNA. We tested the hypothesis that this dysfunction in autonomic modulation in heart failure can be reversed by heart transplantation.
  
  
  RESULTS
  We performed spectral analysis of resting MSNA, R-R interval, and respiration in 9 patients with heart transplants, 9 chronic heart failure patients, and 9 normal control subjects, all closely matched for age, sex, and body mass index. MSNA (bursts per minute) was higher in patients with heart transplants (74+/-3) than either patients with heart failure (56+/-6) or normal subjects (40+/-4) (P<0.001). LF variability in the R-R interval was reduced in both heart transplant recipients and heart failure patients compared with the control subjects (P<0.01). The LF variability in MSNA was also nearly absent in the heart failure patients (P<0.01). However, the LF and HF oscillations in MSNA in patients with heart transplants were comparable to those evident in the control subjects.
  
  
  CONCLUSIONS
  Cardiac transplantation does not reduce MSNA. However, LF oscillations in sympathetic activity are restored after transplantation such that the MSNA oscillatory profile is similar to that observed in normal subjects.
authors: Hypertension Clinic, Department of Cardiology, Erasme Hospital, Belgium.
authors: P
authors: P
authors: van de Borne
authors: N
authors: N
authors: Montano
authors: K
authors: K
authors: Narkiewicz
authors: J P
authors: JP
authors: Degaute
authors: R
authors: R
authors: Oren
authors: M
authors: M
authors: Pagani
authors: V K
authors: VK
authors: Somers
mesh_terms: D005260:Female; D006329:Heart Conduction System / Q000502:physiology*; D006333:Heart Failure / Q000503:physiopathology; D016027:Heart Transplantation; D006801:Humans; D008297:Male; D008875:Middle Aged; D012119:Respiration; D013564:Sympathetic Nervous System / Q000502:physiology*