title: Iodine-123 metaiodobenzylguanidine scintigraphic assessment of the transplanted human heart: evidence for late reinnervation.
abstract: OBJECTIVE
  This study attempted to determine whether cardiac sympathetic reinnervation occurs late after orthotopic heart transplantation.
  
  
  BACKGROUND
  Metaiodobenzylguanidine (MIBG) is taken up by myocardial sympathetic nerves. Iodine-123 (I-123) MIBG cardiac uptake reflects intact myocardial sympathetic innervation of the heart. Cardiac transplant recipients do not demonstrate I-123 MIBG cardiac uptake when studied < 6 months from transplantation. However, physiologic and biochemical studies suggest that sympathetic reinnervation of the heart can occur > 1 year after transplantation.
  
  
  METHODS
  We performed serial cardiac I-123 MIBG imaging in 23 cardiac transplant recipients early (< or = 1 year) and late (> 1 year) after operation. In 16 subjects transmyocardial norepinephrine release was measured late after transplantation.
  
  
  RESULTS
  No subject had visible I-123 MIBG uptake on imaging < 1 year after transplantation. However, 11 (48%) of 23 subjects developed visible cardiac I-123 MIBG uptake 1 to 2 years after transplantation. Only 3 (25%) of 12 subjects with a pretransplantation diagnosis of idiopathic cardiomyopathy demonstrated I-123 MIBG uptake compared with 8 (73%) of 11 with a pretransplantation diagnosis of ischemic or rheumatic heart disease (p = 0.04). All 10 subjects with a net myocardial release of norepinephrine had cardiac I-123 MIBG uptake; all 6 subjects without a net release of norepinephrine had no cardiac I-123 MIBG uptake.
  
  
  CONCLUSIONS
  Sympathetic reinnervation of the transplanted human heart can occur > 1 year after operation, as assessed by I-123 MIBG imaging and the transmyocardial release of norepinephrine. Reinnervation is less likely to occur in patients with a pretransplantation diagnosis of idiopathic cardiomyopathy than in those with other etiologies of congestive heart failure.
authors.affiliation: Department of Medicine, University of California at San Francisco.
authors.forename: T
authors.initials: T
authors.lastname: De Marco
authors.forename: M
authors.initials: M
authors.lastname: Dae
authors.forename: M S
authors.initials: MS
authors.lastname: Yuen-Green
authors.forename: S
authors.initials: S
authors.lastname: Kumar
authors.forename: K
authors.initials: K
authors.lastname: Sudhir
authors.forename: F
authors.initials: F
authors.lastname: Keith
authors.forename: T M
authors.initials: TM
authors.lastname: Amidon
authors.forename: C
authors.initials: C
authors.lastname: Rifkin
authors.forename: C
authors.initials: C
authors.lastname: Klinski
authors.forename: D
authors.initials: D
authors.lastname: Lau
mesh_terms: D019797:3-Iodobenzylguanidine; D000328:Adult; D002311:Cardiomyopathy, Dilated / Q000503:physiopathology / Q000601:surgery; D005260:Female; D006321:Heart / Q000000981:diagnostic imaging* / Q000294:innervation*; D006333:Heart Failure / Q000503:physiopathology / Q000601:surgery; D016027:Heart Transplantation / Q000000981:diagnostic imaging* / Q000502:physiology; D006801:Humans; D007457:Iodine Radioisotopes; D007462:Iodobenzenes; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000503:physiopathology / Q000601:surgery; D009206:Myocardium / Q000378:metabolism; D009416:Nerve Regeneration; D009638:Norepinephrine / Q000378:metabolism; D011877:Radionuclide Imaging; D012214:Rheumatic Heart Disease / Q000503:physiopathology / Q000601:surgery; D013564:Sympathetic Nervous System / Q000503:physiopathology
chemical_list: D007457:Iodine Radioisotopes; D007462:Iodobenzenes; D019797:3-Iodobenzylguanidine; D009638:Norepinephrine