title: Microembolism and catheter ablation I: a comparison of irrigated radiofrequency and multielectrode-phased radiofrequency catheter ablation of pulmonary vein ostia.
abstract: BACKGROUND
  Cerebral diffusion-weighted MRI lesions have been observed after catheter ablation of atrial fibrillation. We hypothesized that conditions predisposing to microembolization could be identified using a porcine model of pulmonary vein ablation and an extracorporeal circulation loop.
  
  
  RESULTS
  Ablations of the pulmonary veins were performed in 18 swine with echo monitoring. The femoral artery and vein were cannulated and an extracorporeal circulation loop with 2 ultrasonic bubble detectors and a 73-μm filter were placed in series. Microemboli and microbubbles were compared between ablation with an irrigated radiofrequency system (Biosense-Webster) and a phased radiofrequency multielectrode system (pulmonary vein ablation catheter [PVAC], Medtronic, Inc, Carlsbad, CA) in unipolar and 3 blended unipolar/bipolar modes. Animal pathology was examined. The size and number of microbubbles observed during ablation ranged from 30 to 180 μm and 0 to 3253 bubbles per ablation. Microbubble volumes with PVAC (29.1 nL) were greater than with irrigated radiofrequency (0.4 nL; P=0.045), and greatest with type II or III microbubbles on transesophageal echocardiography. Ablation with the PVAC showed fewest microbubbles in the unipolar mode (P=0.012 versus bipolar). The most occurred during bipolar energy delivery with overlap of proximal and distal electrodes (median microbubble volume, 1744 nL; interquartile range, 737-4082 nL; maximum, 19 516 nL). No cerebral MRI lesions were seen, but 2 animals had renal embolization.
  
  
  CONCLUSIONS
  Left atrial ablation with irrigated radiofrequency and PVAC catheters in swine is associated with microbubble and microembolus production. Avoiding overlap of electrodes 1 and 10 on PVAC should reduce the microembolic burden associated with this procedure.
authors: Department of Cardiovascular Medicine, Oakland University William Beaumont School of Medicine, Royal Oak, MI 48073, USA. dhaines@beaumont.edu
authors: David E
authors: DE
authors: Haines
authors: Mark T
authors: MT
authors: Stewart
authors: Sarah
authors: S
authors: Dahlberg
authors: Noah D
authors: ND
authors: Barka
authors: Cathy
authors: C
authors: Condie
authors: Gary R
authors: GR
authors: Fiedler
authors: Nicole A
authors: NA
authors: Kirchhof
authors: Franck
authors: F
authors: Halimi
authors: Thomas
authors: T
authors: Deneke
mesh_terms: D000818:Animals; D062906:Cardiac Catheters; D017115:Catheter Ablation / Q000009:adverse effects* / Q000295:instrumentation*; D038524:Diffusion Magnetic Resonance Imaging; D017548:Echocardiography, Transesophageal; D004566:Electrodes; D057505:Embolic Protection Devices; D004617:Embolism / Q000175:diagnosis / Q000209:etiology* / Q000473:pathology / Q000517:prevention & control; D004618:Embolism, Air / Q000175:diagnosis / Q000209:etiology / Q000473:pathology / Q000517:prevention & control; D004867:Equipment Design; D005112:Extracorporeal Circulation; D045423:Microbubbles; D023421:Models, Animal; D011667:Pulmonary Veins / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D013552:Swine; D007507:Therapeutic Irrigation / Q000009:adverse effects* / Q000295:instrumentation*; D013997:Time Factors; D018084:Ultrasonography, Interventional / Q000379:methods