title: Interatrial pressure gradients during simulated obstructive sleep apnea: a catheter-based study.
abstract: OBJECTIVE
  We set to measure the interatrial pressure gradient during simulated obstructive sleep apnea (OSA).
  
  
  BACKGROUND
  OSA occurs when a sleeping patient attempts to inhale against an obstructed airway. How this event affects the interatrial pressure gradient has not been defined. We hypothesized that simulated OSA in a conscious subject (Mueller maneuver [MM], inspiration against obstruction) would promote increased right-to-left pressure gradient, and then the substrate for right-to-left atrial shunting.
  
  
  METHODS
  Selected patients underwent simultaneous measurement of airway and atrial pressures (both left and right atrium [LA, RA]) using high-fidelity micromanometry at rest, during MM, and during VM, during right heart catheterization.
  
  
  RESULTS
  Ten patients (age 55 ± 11 years, two women) were successfully studied. During the onset of MM, RA pressure transiently but consistently exceeded LA pressure in response to the steep decline in intrathoracic pressure (maximum RA-LA pressure gradient increased from 0.1 ± 1.4 mm Hg at baseline to 7.0 ± 4.3 mm Hg during MM, P < 0.001). The maximum right-to-left atrial pressure gradient during Mueller maneuver was higher than that achieved during the Valsalva maneuver release (P < 0.007).
  
  
  CONCLUSIONS
  The onset of MM increased right-to-left pressure gradient across the atrial septum, likely as a result of greater blood return to the RA from extrathoracic veins. The RA-LA pressure gradient achieved during MM was greater than that observed during VM. These findings delineate the hemodynamic substrate for right to left shunting during OSA.
authors.affiliation: Department of Cardiovascular Diseases and Internal Medicine, Mayo Clinic, Rochester, Minnesota; Department of Cardiology International Clinical Research Center (ICRC), St. Anne's Hospital, Brno, Czech Republic.
authors.forename: Tomas
authors.initials: T
authors.lastname: Konecny
authors.forename: Amber D
authors.initials: AD
authors.lastname: Khanna
authors.forename: Jan
authors.initials: J
authors.lastname: Novak
authors.forename: Abdi A
authors.initials: AA
authors.lastname: Jama
authors.forename: George M
authors.initials: GM
authors.lastname: Zawadowski
authors.forename: Marek
authors.initials: M
authors.lastname: Orban
authors.forename: Gregg
authors.initials: G
authors.lastname: Pressman
authors.forename: Jan
authors.initials: J
authors.lastname: Bukartyk
authors.forename: Tomas
authors.initials: T
authors.lastname: Kara
authors.forename: Frank
authors.initials: F
authors.lastname: Cetta
authors.forename: Barry A
authors.initials: BA
authors.lastname: Borlaug
authors.forename: Virend K
authors.initials: VK
authors.lastname: Somers
authors.forename: Guy S
authors.initials: GS
authors.lastname: Reeder
mesh_terms: D016280:Atrial Function, Right / Q000502:physiology*; D062185:Atrial Pressure / Q000502:physiology*; D006328:Cardiac Catheterization / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006325:Heart Atria / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008365:Manometry / Q000379:methods; D008875:Middle Aged; D016544:Patient Simulation; D011446:Prospective Studies; D020181:Sleep Apnea, Obstructive / Q000503:physiopathology*; D014636:Valsalva Maneuver
keywords: foramen ovale; gradient; mueller maneuver; pressure; sleep apnea; valsalva maneuver