title: Construction of a three-dimensional outline of the heart and conduction pathway by means of a 64-channel magnetocardiogram in patients with atrial flutter and fibrillation.
abstract: BACKGROUND
  Magnetocardiography (MCG) has the potential for collecting three-dimensional (3D) intracardiac electric information, because the magnetic field is unaffected by the shape of the lungs and torso. In the present study, we report on the generation of a 3D heart outline and conduction pathway by means of a current density map using a 64-channel SQUID system, and an evaluation of its significance in patients with atrial flutter (AFL) and atrial fibrillation (AFIB).
  
  
  METHODS
  The subjects consisted of 20 healthy volunteers, and 3 patients with AFL and 4 patients with AFIB. A 64-channel MCG was recorded after digitization at 500 Hz, and a 3D current density was reconstructed from the magnetic fields using a space filter in conjunction with the minimum normalization method of Tikhonov. A 3D heart outline was generated from the integrated current density by the space filter. The conduction pathway was superimposed on a heart outline generated by a magnetic field. The heart outline was verified by the silhouette on the magnetic resonance (MR) images. An MCG was recorded pre- and post interventional therapy, and therapeutic efficacy was evaluated.
  
  
  RESULTS
  The 3D heart outline of the atrium and ventricle corresponded to the silhouette of the right atrium and left ventricle, respectively, on an MR image. The serial conduction pathway of the QRS segment superimposed on the 3D heart outline map demonstrated the conduction pattern generated within the heart. The MCG revealed a counter-clockwise rotation in patients with AFL, and random micro-reentry in the case of AFIB. After interventional therapy, restoration of the sinus rhythm was verified in patients with both AFL and AFIB.
  
  
  CONCLUSIONS
  A 64-channel MCG was used to evaluate the 3D heart outline and conduction pathway in patients with AFL and AFIB without the need for MR images. Condensed Abstract A 64-channel MCG was used to evaluate the 3D heart out line and conduction pathway in patients with AFL and AFIB.
authors.affiliation: The Department of Laboratory Medicine, Iwate Medical University, 19-1 Uchimaru, Morioka, Japan, 020-8505. knakai@iwate-med.ac.jp
authors.forename: Kenji
authors.initials: K
authors.lastname: Nakai
authors.forename: Kohei
authors.initials: K
authors.lastname: Kawazoe
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Izumoto
authors.forename: Junichi
authors.initials: J
authors.lastname: Tsuboi
authors.forename: Yu
authors.initials: Y
authors.lastname: Oshima
authors.forename: Takanori
authors.initials: T
authors.lastname: Oka
authors.forename: Kunihiro
authors.initials: K
authors.lastname: Yoshioka
authors.forename: Masanori
authors.initials: M
authors.lastname: Shozushima
authors.forename: Akira
authors.initials: A
authors.lastname: Suwabe
authors.forename: Manabu
authors.initials: M
authors.lastname: Itoh
authors.forename: Koichiro
authors.initials: K
authors.lastname: Kobayashi
authors.forename: Takayuki
authors.initials: T
authors.lastname: Shimizu
authors.forename: Masahito
authors.initials: M
authors.lastname: Yoshizawa
mesh_terms: D000368:Aged; D001281:Atrial Fibrillation / Q000503:physiopathology*; D001282:Atrial Flutter / Q000503:physiopathology*; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008280:Magnetics; D008297:Male; D008875:Middle Aged; D009206:Myocardium / Q000473:pathology; D012815:Signal Processing, Computer-Assisted