title: Exercise training in chronic heart failure: beneficial effects on cardiac (11)C-hydroxyephedrine PET, autonomic nervous control, and ventricular repolarization.
abstract: Abnormalities of autonomic nervous function are associated with a poor prognosis of patients with chronic heart failure (CHF). We studied the effects of a 6-mo exercise training program on Q-T interval dispersion, heart rate and blood pressure variability, baroreflex sensitivity, myocardial blood flow (MBF), and presynaptic sympathetic innervation in 13 patients with New York Heart Association class II-III heart failure.
  
  
  METHODS
  MBF was measured with the H(2)(15)O and C(15)O technique. Cardiac presynaptic innervation was studied by (11)C-hydroxyephedrine (HED) retention assessed with PET. Heart rate and blood pressure variability and baroreflex sensitivity were tested with the phenylephrine method. All studies were performed before and after a 6-mo exercise training program. The exercise capacity was determined by spiroergometry, and Q-T dispersion was measured from a standard 12-lead electrocardiogram.
  
  
  RESULTS
  Q-T dispersion was reduced after the training period (mean +/- SEM, from 52 +/- 5 to 36 +/- 5 ms [P = 0.01]). Global (11)C-HED retention improved from 0.228 +/- 0.099 to 0.263 +/- 0.066 s(-1) (P < 0.05). Global MBF was not affected by training, but MBF increased in areas of low initial perfusion in patients with coronary artery disease (from 0.382 +/- 0.062 to 0.562 +/- 0.083 mL/g/min [P < 0.005]). The high-frequency spectrum and total R-R interval variability increased (from 4.53 +/- 0.30 to 5.02 +/- 0.36 ms(2) [P < 0.05] and from 3.60 +/- 0.34 to 4.31 +/- 0.37 ms(2) [P < 0.005], respectively). Both changes correlated significantly with the observed change in (11)C-HED retention. There was a significant reduction of total and a near-significant reduction of low-frequency (LF) systolic blood-pressure (SBP) variability (from 4.89 +/- 1.03 to 3.18 +/- 0.48 [P < 0.05] and from 2.79 +/- 0.38 to 1.76 +/- 0.24 [P = 0.059], respectively). The decrease in LF SBP variability correlated inversely with the enhancement of (11)C-HED retention (r = -0.66; P < 0.05). Baroreflex sensitivity increased from 5.83 +/- 0.82 to 10.15 +/- 1.66 ms/mm Hg (P < 0.05).
  
  
  CONCLUSIONS
  Exercise training induces beneficial changes in functional and imaging measures of cardiovascular autonomic nervous control. These observations point to a training-induced shift toward normalization of the compensatory autonomic nervous imbalance in CHF.
authors.affiliation: Department of Medicine, Turku University Central Hospital, Turku, Finland. mikko.pietila@tyks.fi
authors.forename: Mikko
authors.initials: M
authors.lastname: Pietilä
authors.forename: Kimmo
authors.initials: K
authors.lastname: Malminiemi
authors.forename: Risto
authors.initials: R
authors.lastname: Vesalainen
authors.forename: Tuomas
authors.initials: T
authors.lastname: Jartti
authors.forename: Mika
authors.initials: M
authors.lastname: Teräs
authors.forename: Kjell
authors.initials: K
authors.lastname: Någren
authors.forename: Pertti
authors.initials: P
authors.lastname: Lehikoinen
authors.forename: Liisa-Maria
authors.initials: LM
authors.lastname: Voipio-Pulkki
mesh_terms: D001341:Autonomic Nervous System / Q000502:physiology*; D002250:Carbon Radioisotopes; D004562:Electrocardiography; D005081:Exercise Therapy; D005260:Female; D006321:Heart / Q000000981:diagnostic imaging*; D006333:Heart Failure / Q000000981:diagnostic imaging / Q000534:rehabilitation*; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D014055:Tomography, Emission-Computed
chemical_list: D002250:Carbon Radioisotopes