title: Electrophysiological effects of acute atrial stretch on persistent atrial fibrillation in patients undergoing open heart surgery.
abstract: BACKGROUND
  The electrophysiologic effects of acute atrial dilatation and dedilatation in humans with chronic atrial fibrillation remains to be elucidated.
  
  
  OBJECTIVE
  To study the electrophysiological effects of acute atrial dedilatation and subsequent dilatation in patients with long-standing persistent atrial fibrillation (AF) with structural heart disease undergoing elective cardiac surgery.
  
  
  METHODS
  Nine patients were studied. Mean age was 71 ± 10 years, and left ventricular ejection was 46% ± 6%. Patients had at least moderate mitral valve regurgitation and dilated atria. After sternotomy and during extracorporal circulation, mapping was performed on the beating heart with 2 multielectrode arrays (60 electrodes each, interelectrode distance 1.5 mm) positioned on the lateral wall of the right atrium (RA) and left atrium (LA). Atrial pressure and size were altered by modifying extracorporal circulation. AF electrograms were recorded at baseline after dedilation and after dilatation of the atria afterward.
  
  
  RESULTS
  At baseline, the median AF cycle length (mAFCL) was 184 ± 27 ms in the RA and 180 ± 17 ms in the LA. After dedilatation, the mAFCL shortened significantly to 168 ± 13 ms in the RA and to 168 ± 20 ms in the LA. Dilatation lengthened mAFCL significantly to 189 ± 17 ms in the RA and to 185 ± 23 ms in the LA. Conduction block (CB) at baseline was 14.3% ± 3.6% in the RA and 17.3% ± 5.5% in the LA. CB decreased significantly with dedilatation to 7.4% ± 2.9% in the RA and to 7.9% ± 6.3% in the LA. CB increased significantly with dilatation afterward to 15.0% ± 8.3% in the RA and to 18.5% ± 16.0% in the LA.
  
  
  CONCLUSIONS
  Acute dedilatation of the atria in patients with long-standing persistent AF causes a decrease in the mAFCL in both atria. Subsequent dilatation increased the mAFCL. The amount of CB decreased with dedilatation and increased with dilatation afterward in both atria.
authors.affiliation: Department of Cardiology, Isala Klinieken, Zwolle, The Netherlands. v.r.c.derks@isala.nl
authors.forename: Arif
authors.initials: A
authors.lastname: Elvan
authors.forename: Ahmet
authors.initials: A
authors.lastname: Adiyaman
authors.forename: Rypko J
authors.initials: RJ
authors.lastname: Beukema
authors.forename: Hauw T
authors.initials: HT
authors.lastname: Sie
authors.forename: Maurits A
authors.initials: MA
authors.lastname: Allessie
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001281:Atrial Fibrillation / Q000150:complications / Q000503:physiopathology / Q000628:therapy*; D018780:Body Surface Potential Mapping / Q000379:methods*; D006348:Cardiac Surgical Procedures / Q000379:methods*; D017115:Catheter Ablation / Q000379:methods*; D002908:Chronic Disease; D004106:Dilatation / Q000379:methods*; D017558:Elective Surgical Procedures / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006325:Heart Atria; D006329:Heart Conduction System / Q000601:surgery; D006331:Heart Diseases / Q000150:complications / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011300:Preoperative Care; D016896:Treatment Outcome