title: Optical coherence tomography captures rapid hemodynamic responses to acute hypoxia in the cardiovascular system of early embryos.
abstract: BACKGROUND
  The trajectory to heart defects may start in tubular and looping heart stages when detailed analysis of form and function is difficult by currently available methods. We used a novel method, Doppler optical coherence tomography (OCT), to follow changes in cardiovascular function in quail embryos during acute hypoxic stress. Chronic fetal hypoxia is a known risk factor for congenital heart diseases (CHDs). Decreased fetal heart rates during maternal obstructive sleep apnea suggest that studying fetal heart responses under acute hypoxia is warranted.
  
  
  RESULTS
  We captured responses to hypoxia at the critical looping heart stages. Doppler OCT revealed detailed vitelline arterial pulsed Doppler waveforms. Embryos tolerated 1 hr of hypoxia (5%, 10%, or 15% O(2) ), but exhibited changes including decreased systolic and increased diastolic duration in 5 min. After 5 min, slower heart rates, arrhythmic events and an increase in retrograde blood flow were observed. These changes suggested slower filling of the heart, which was confirmed by four-dimensional Doppler imaging of the heart itself.
  
  
  CONCLUSIONS
  Doppler OCT is well suited for rapid noninvasive screening for functional changes in avian embryos under near physiological conditions. Analysis of the accessible vitelline artery sensitively reflected changes in heart function and can be used for rapid screening. Acute hypoxia caused rapid hemodynamic changes in looping hearts and may be a concern for increased CHD risk.
authors.affiliation: Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio, USA.
authors.forename: Shi
authors.initials: S
authors.lastname: Gu
authors.forename: Michael W
authors.initials: MW
authors.lastname: Jenkins
authors.forename: Lindsy M
authors.initials: LM
authors.lastname: Peterson
authors.forename: Yong-Qiu
authors.initials: YQ
authors.lastname: Doughman
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Rollins
authors.forename: Michiko
authors.initials: M
authors.lastname: Watanabe
mesh_terms: D000818:Animals; D002319:Cardiovascular System / Q000503:physiopathology*; D004625:Embryo, Nonmammalian / Q000098:blood supply* / Q000503:physiopathology*; D005311:Fetal Hypoxia / Q000503:physiopathology*; D006330:Heart Defects, Congenital / Q000196:embryology* / Q000503:physiopathology; D006339:Heart Rate; D006439:Hemodynamics; D011784:Quail; D041623:Tomography, Optical Coherence