title: Cardiac resynchronization therapy and cardiac sympathetic function.
abstract: BACKGROUND
  Cardiac resynchronization therapy (CRT) is an established therapy for advanced congestive heart failure, improving both survival and hospitalization. The mechanism beneath these improvements still needs to be defined as about one-third of the patients do not benefit from resynchronization. Restoration of sympatho-vagal function can play a significant role in the process, but available data are limited. In this scenario, positron emission tomography scans with (11) C-hydroxyephedrine, a noradrenaline analogous, has the potential to characterize the modifications of the sympathetic nervous system induced by CRT in decompensated patients.
  
  
  METHODS
  Ten patients (six males, age 68 ± 10 years) with primary dilated cardiomyopathy were studied before and after resynchronization (acutely and after 3 months), from a clinical and echocardiographic point of view. Their cardiac sympathetic nerve activity was evaluated by (11) C-hydroxyephedrine positron emission tomography before resynchronization, at short and medium term after resynchronization.
  
  
  RESULTS
  Responders to CRT (patients showing ≥ 15% decrease in left ventricular end-systolic volume) showed a higher level of left ventricular radiotracer uptake both at baseline and after resynchronization with respect to nonresponders. This was coupled with a progressive improvement in homogeneity in left ventricular tracer uptake mainly in responders.
  
  
  CONCLUSIONS
  Cardiac resynchronization therapy improves cardiac sympathetic nerve activity in responders since its activation, while nonresponders do not show any significant change at any time of evaluation. CRT seems to be more effective in those patients with a still structurally preserved, yet functionally impaired, neuroautonomic system.
authors.affiliation: Institute of Cardiology, University Hospital S. Orsola-Malpighi Bologna, University of Bologna, Bologna, Italy.
authors.forename: Cristian
authors.initials: C
authors.lastname: Martignani
authors.affiliation: Institute of Cardiology, University Hospital S. Orsola-Malpighi Bologna, University of Bologna, Bologna, Italy.
authors.forename: Igor
authors.initials: I
authors.lastname: Diemberger
authors.affiliation: Department of Nuclear Medicine, University Hospital S. Orsola-Malpighi Bologna, University of Bologna, Bologna, Italy.
authors.forename: Cristina
authors.initials: C
authors.lastname: Nanni
authors.affiliation: Institute of Cardiology, University Hospital S. Orsola-Malpighi Bologna, University of Bologna, Bologna, Italy.
authors.forename: Mauro
authors.initials: M
authors.lastname: Biffi
authors.affiliation: Institute of Cardiology, University Hospital S. Orsola-Malpighi Bologna, University of Bologna, Bologna, Italy.
authors.forename: Matteo
authors.initials: M
authors.lastname: Ziacchi
authors.affiliation: Department of Nuclear Medicine, University Hospital S. Orsola-Malpighi Bologna, University of Bologna, Bologna, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Boschi
authors.affiliation: Institute of Cardiology, University Hospital S. Orsola-Malpighi Bologna, University of Bologna, Bologna, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Corzani
authors.affiliation: Department of Nuclear Medicine, University Hospital S. Orsola-Malpighi Bologna, University of Bologna, Bologna, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Fanti
authors.affiliation: Department of Health Science, Nuclear Medicine, IRCCS AOU San Martino - IST, University of Genoa, Genoa, Italy.
authors.forename: Gianmario
authors.initials: G
authors.lastname: Sambuceti
authors.affiliation: Institute of Cardiology, University Hospital S. Orsola-Malpighi Bologna, University of Bologna, Bologna, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Boriani
mesh_terms: D000368:Aged; D002250:Carbon Radioisotopes; D058406:Cardiac Resynchronization Therapy; D002311:Cardiomyopathy, Dilated / Q000000981:diagnostic imaging* / Q000628:therapy; D015331:Cohort Studies; D004452:Echocardiography; D004809:Ephedrine / Q000031:analogs & derivatives; D005260:Female; D006321:Heart / Q000000981:diagnostic imaging*; D006333:Heart Failure / Q000000981:diagnostic imaging* / Q000628:therapy; D006801:Humans; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography; D011446:Prospective Studies; D019275:Radiopharmaceuticals; D013318:Stroke Volume; D013564:Sympathetic Nervous System / Q000000981:diagnostic imaging* / Q000503:physiopathology; D013566:Sympathomimetics; D016896:Treatment Outcome
chemical_list: D002250:Carbon Radioisotopes; D019275:Radiopharmaceuticals; D013566:Sympathomimetics; D004809:Ephedrine
keywords: 11C-hydroxyephedrine; cardiac resynchronization therapy; heart failure; neuroautonomic system; positron emission tomography