title: Quantitative cardiovascular magnetic resonance in pregnant women: cross-sectional analysis of physiological parameters throughout pregnancy and the impact of the supine position.
abstract: BACKGROUND
  There are physiological reasons for the effects of positioning on hemodynamic variables and cardiac dimensions related to altered intra-abdominal and intra-thoracic pressures. This problem is especially evident in pregnant women due to the additional aorto-caval compression by the enlarged uterus. The purpose of this study was to investigate the effect of postural changes on cardiac dimensions and function during mid and late pregnancy using cardiovascular magnetic resonance (CMR).
  
  
  METHODS
  Healthy non-pregnant women, pregnant women at 20th week of gestation and at 32nd week of gestation without history of cardiac disease were recruited to the study and underwent CMR in supine and left lateral positions. Cardiac hemodynamic parameters and dimensions were measured and compared between both positions.
  
  
  RESULTS
  Five non-pregnant women, 6 healthy pregnant women at mid pregnancy and 8 healthy pregnant women at late pregnancy were enrolled in the study. In the group of non-pregnant women left ventricular (LV) cardiac output (CO) significantly decreased by 9% (p=0.043) and right ventricular (RV) end-diastolic volume (EDV) significantly increased by 5% (p=0.043) from the supine to the left lateral position. During mid pregnancy LV ejection fraction (EF), stroke volume (SV), left atrium lateral diameter and left atrial supero-inferior diameter increased significantly from the supine position to the left lateral position: 8%, 27%, 5% and 11%, respectively (p<0.05). RV EDV, SV and right atrium supero-inferior diameter significantly increased from the supine to the left lateral position: 25%, 31% and 13% (p<0.05), respectively. During late pregnancy a significant increment of LV EF, EDV, SV and CO was observed in the left lateral position: 11%, 21%, 35% and 24% (p<0.05), respectively. Left atrial diameters were significantly larger in the left lateral position compared to the supine position (p<0.05). RV CO was significantly increased in the left lateral position compared to the supine position (p<0.05).
  
  
  CONCLUSIONS
  During pregnancy positional changes affect significantly cardiac hemodynamic parameters and dimensions. Pregnant women who need serial studies by CMR should be imaged in a consistent position. From as early as 20 weeks the left lateral position should be preferred on the supine position because it positively affects venous return, SV and CO.
authors.affiliation: Department of Cardiology, Erasmus University Medical Center's, Gravendijkwal 230, 3015CE Rotterdam, The Netherlands.
authors.forename: Alexia
authors.initials: A
authors.lastname: Rossi
authors.forename: Jerome
authors.initials: J
authors.lastname: Cornette
authors.forename: Mark R
authors.initials: MR
authors.lastname: Johnson
authors.forename: Yusuf
authors.initials: Y
authors.lastname: Karamermer
authors.forename: Tirza
authors.initials: T
authors.lastname: Springeling
authors.forename: Petra
authors.initials: P
authors.lastname: Opic
authors.forename: Adriaan
authors.initials: A
authors.lastname: Moelker
authors.forename: Gabriel P
authors.initials: GP
authors.lastname: Krestin
authors.forename: Eric
authors.initials: E
authors.lastname: Steegers
authors.forename: Jolien
authors.initials: J
authors.lastname: Roos-Hesselink
authors.forename: Robert-Jan M
authors.initials: RJ
authors.lastname: van Geuns
mesh_terms: D000328:Adult; D016279:Atrial Function, Left; D016280:Atrial Function, Right; D002302:Cardiac Output; D016022:Case-Control Studies; D005260:Female; D005865:Gestational Age; D006439:Hemodynamics; D006801:Humans; D019028:Magnetic Resonance Imaging, Cine; D009426:Netherlands; D056888:Patient Positioning; D011237:Predictive Value of Tests; D011247:Pregnancy; D011249:Pregnancy Complications, Cardiovascular / Q000175:diagnosis* / Q000503:physiopathology; D013318:Stroke Volume; D016683:Supine Position; D016277:Ventricular Function, Left; D016278:Ventricular Function, Right; D055815:Young Adult