title: Dynamic cycling in atrial size and flow during obstructive apnoea.
abstract: Obstructive sleep apnoea (OSA) is strongly associated with cardiovascular disease. However, acute cardiovascular effects of repetitive airway obstruction are poorly understood. While past research used a sustained Mueller manoeuver to simulate OSA we employed a series of gasping efforts to better simulate true obstructive apnoeas. This report describes acute changes in cardiac anatomy and flow related to sudden changes in intrathoracic pressure.
  
  
  
  26 healthy, normal weight participants performed 5-6 gasping efforts (target intrathoracic pressure -40 mm Hg) while undergoing Doppler echocardiography. 14 participants had sufficient echocardiographic images to allow comparison of atrial areas during the manoeuver with baseline measurements. Mitral and tricuspid E-wave and A-wave velocities postmanoeuver were compared with baseline in all participants. Average atrial areas changed little during the manoeuver, but variance in both atrial areas was significantly greater than baseline. Further, an inverse relationship was noted with left atrial collapse and right atrial enlargement at onset of inspiratory effort. Significant inverse changes were noted in Doppler flow when comparing the first beat postmanoeuver (pMM1) with baseline. Mitral E-wave velocity increased 9.1 cm/s while tricuspid E-wave velocity decreased 7.0 cm/s; by the eighth beat postmanoeuver (pMM8) values were not different from baseline. Mitral and tricuspid A-wave velocities were not different from baseline at pMM1, but both were significantly higher by pMM8.
  
  
  
  Repetitive obstructive apnoeas produce dynamic, inverse changes in atrial size and Doppler flow across the atrioventricular valves. These observations have important implications for understanding the pathophysiology of OSA.
authors.affiliation: Heart and Vascular Institute, Einstein Medical Center , Philadelphia, Pennsylvania , USA.
authors.forename: Gregg S
authors.initials: GS
authors.lastname: Pressman
authors.affiliation: Heart and Vascular Institute, Einstein Medical Center , Philadelphia, Pennsylvania , USA.
authors.forename: Beatriz
authors.initials: B
authors.lastname: Cepeda-Valery
authors.affiliation: Heart and Vascular Institute, Einstein Medical Center , Philadelphia, Pennsylvania , USA.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Codolosa
authors.affiliation: International Clinical Research Center, St Anne's University Hospital, Brno, Czech Republic; Department of Human Pharmacology and Toxicology, Faculty of Pharmacy, University of Veterinary and Pharmaceutical Sciences, Brno, Czech Republic.
authors.forename: Marek
authors.initials: M
authors.lastname: Orban
authors.affiliation: Office of Research and Technology Development, Einstein Medical Center , Philadelphia, Pennsylvania , USA.
authors.forename: Solomon P
authors.initials: SP
authors.lastname: Samuel
authors.affiliation: Division of Cardiovascular Diseases , Mayo Clinic , Rochester, Minnesota , USA.
authors.forename: Virend K
authors.initials: VK
authors.lastname: Somers