title: Esophageal dilation with integrated balloon imaging: initial evaluation in a porcine model.
abstract: BACKGROUND
  When treating achalasia, balloon dilation is often combined with fluoroscopy to allow the lower esophageal sphincter to be visualized as it is being dilated. We sought to evaluate a new balloon dilation technology, EsoFLIP, which allows the shape of the balloon to be visualized in a nonradiographic manner by using impedance planimetry electrodes located within the dilation balloon.
  
  
  METHODS
  Two pigs weighing 35 kg were used. The EsoFLIP balloon dilator was introduced under endoscopic visualization. Successive injections of 50, 60, 70 and 85 mL into the dilation balloon permitted dilations at increasing diameters to be achieved. Following each dilation fluid was withdrawn to leave 30 mL in the balloon and an EsoFLIP image was captured to track progressive dilation of the gastroesophageal junction (GEJ).
  
  
  RESULTS
  The EsoFLIP catheter was safely deployed in the two pigs and no complications were noted. For pig 1, during dilation, the measured balloon diameter at the waist was 24.1, 28.9, 29.2 and 30.0 mm for balloon dilation volumes of 50, 60, 70 and 85 mL respectively. For pig 2 the corresponding diameter at the waist was 22.8, 27.1, 28.5 and 29.4 mm. The GEJ diameter increased from 12.5 and 12.4 mm to 17.4 and 17.5mm for pigs 1 and 2 respectively. Distensibility of the GEJ in pig 1 increased from 2.3 mm(2)/mmHg before to 4.4 mm(2)/mmHg after dilation and in pig 2 from 4.4 to 9.6 mm(2)/mmHg. The GEJ substantively achieved its final diameter after the dilation using just 50 mL in the balloon.
  
  
  CONCLUSIONS
  We demonstrated technical feasibility and safety of the EsoFLIP dilator in a porcine model. Further studies in humans with achalasia remain to be conducted, which, besides demonstrating technical feasibility, should also evaluate the use of distensibility measurements taken during dilation to predict outcomes.
authors.affiliation: Adjunct Professor of Engineering, Department of Engineering and Informatics, NUI Galway, University Rd, Galway, Ireland.
authors.forename: John
authors.initials: J
authors.lastname: O'Dea
authors.forename: Peter D
authors.initials: PD
authors.lastname: Siersema
keywords: Achalsia; balloon dilation; esophageal