title: The impact of respiration on left atrial and pulmonary venous anatomy: implications for image-guided intervention.
abstract: BACKGROUND
  Image-guided intervention using pre-acquired CT/MR 3-dimensional images is an emerging strategy for atrial fibrillation (AF) ablation but may be limited by its use of static images to depict dynamic physiology. The effect of biologic factors such as respiration on the left atrial-pulmonary venous (LA-PV) anatomy is not well understood but is likely to have important implications. Conventional CT/MR imaging is performed during an inspiratory breath-hold, while electroanatomical mapping (EAM) during "quiet" breathing approximates an expiratory breath-hold. This study examined the effects of respiration on LA-PV anatomy and the error introduced by respiration on the integration of EAM with 3D MR imaging.
  
  
  METHODS
  Pre-procedural MRI angiography was performed at both end-expiration (EXP) and end-inspiration (INSP) in 20 patients undergoing AF catheter ablation. 3D INSP and EXP surface reconstructions of the LA-PVs were compared. In selected pts, EAM data acquired during the ablation procedure (n=7) were integrated with the 3D MRI datasets.
  
  
  RESULTS
  Qualitative assessment of the INSP and EXP 3D images revealed splaying of the PVs and reduction in PV caliber of the right-sided PVs during held inspiration. After aligning these two datasets, the average surface-to-surface distance calculated by region ranged from 1.99mm (right middle PV) to 3.79mm (left superior PV). Registration of the EAM to the MRI models was better for the EXP dataset (2.30+/-0.73mm) than the INSP dataset (3.03+/-0.57mm; p=0.004).
  
  
  CONCLUSIONS
  There are significant changes in LA-PV anatomy with respiration. MR images acquired during standard held inspiration may introduce unnecessary errors in registration during image-guided intervention.
authors.affiliation: Cardiac Arrhythmia Service, Radiology Department, Massachusetts General Hospital-Harvard Medical School, 55 Fruit Street, Boston, MA 02114, USA.
authors.forename: Peter A
authors.initials: PA
authors.lastname: Noseworthy
authors.forename: Zachary J
authors.initials: ZJ
authors.lastname: Malchano
authors.forename: Jameel
authors.initials: J
authors.lastname: Ahmed
authors.forename: Godtfred
authors.initials: G
authors.lastname: Holmvang
authors.forename: Jeremy N
authors.initials: JN
authors.lastname: Ruskin
authors.forename: Vivek Y
authors.initials: VY
authors.lastname: Reddy
mesh_terms: D000368:Aged; D001281:Atrial Fibrillation / Q000175:diagnosis / Q000601:surgery*; D017115:Catheter Ablation / Q000379:methods; D005260:Female; D005500:Follow-Up Studies; D006325:Heart Atria / Q000473:pathology*; D006801:Humans; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011667:Pulmonary Veins / Q000473:pathology* / Q000502:physiology; D015203:Reproducibility of Results; D015656:Respiratory Mechanics / Q000502:physiology*; D012720:Severity of Illness Index