title: Microbubbles shunting via a patent foramen ovale impair endothelial function.
abstract: OBJECTIVE
  Exposure to intravascular microbubbles after diving and during medical procedures alters endothelial function. The aim of this study was to investigate whether a patent foramen ovale altered forearm endothelial function by facilitating microbubbles transfer.
  
  
  METHODS
  Patients attended on two separate visits, at least seven days apart receiving agitated saline or no active intervention in random order. On both days, flow-mediated dilatation of the brachial artery was measured using vascular ultrasound. On the intervention visit, agitated saline was injected and the passage of microbubbles into the arterial circulation was confirmed by echocardiography. Serial flow-mediated dilatation measurements were made after agitated saline and at the same time points after no intervention.
  
  
  METHODS
  St Thomas' Hospital in London.
  
  
  METHODS
  Patients with a patent foramen ovale (PFO+n = 14, 9 male, mean ± SD age 42.2 ± 10.5 years) and patients without a patent foramen ovale (PFO- n = 10, 7 male, mean ± SD age 49.4 ± 18.4 years) were recruited.
  
  
  METHODS
  Change in brachial artery flow-mediated dilatation.
  
  
  RESULTS
  In patent foramen ovale + patients, flow-mediated dilatation did not change significantly on the control day but after agitated saline reduced by 2.3 ± 0.3%, 20 minutes after bubble injection (P < 0.005 vs. corresponding change in flow-mediated dilatation during control study). There was no significant change in flow-mediated dilatation for patent foramen ovale- patients at either visit.
  
  
  CONCLUSIONS
  These results suggest that the presence of a patent foramen ovale facilitated impairment of endothelial function acutely by the transfer of microbubbles into the arterial circulation. As a patent foramen ovale is a common condition, this may be relevant to microbubbles exposure in medical procedures and in decompression illness.
authors.affiliation: King's College London, British Heart Foundation Centre, London, UK.
authors.forename: Henry
authors.initials: H
authors.lastname: Fok
authors.affiliation: King's College London, British Heart Foundation Centre, London, UK.
authors.forename: Benyu
authors.initials: B
authors.lastname: Jiang
authors.affiliation: King's College London, British Heart Foundation Centre, London, UK.
authors.forename: Phil
authors.initials: P
authors.lastname: Chowienczyk
authors.affiliation: Guy's and St Thomas NHS Foundation Trust Hospital, London, UK.
authors.forename: Brian
authors.initials: B
authors.lastname: Clapp
keywords: Decompression illness; endothelial dysfunction; flow-mediated dilatation; microbubbles; patent foramen ovale