title: MRI evaluation of maternal cardiac displacement in pregnancy: implications for cardiopulmonary resuscitation.
abstract: OBJECTIVE
  The purpose of this study was to determine, with the use of cardiac magnetic resonance imaging, whether there is vertical displacement of the heart during pregnancy. Cardiopulmonary resuscitation guidelines during pregnancy recommend placing the hands 2-3 cm higher on the sternum than in nonpregnant individuals. This recommendation is based on the presumption that the heart is displaced superiorly by the diaphragm during the third trimester. Whether there is true cardiac displacement because of the expanding uterus in pregnancy remains unknown.
  
  
  METHODS
  A total of 34 healthy female volunteers 18-35 years old were enrolled prospectively from 2010-2012 at 2 tertiary care centers. The conditions of all participants were evaluated with cardiac magnetic resonance imaging in the one-half left lateral decubitus position during the third trimester of pregnancy and again at a minimum of 3 months after delivery (surrogate for the nonpregnant state). Superior displacement of the heart was determined by measurement of the distance between the inferior aspect of the clavicular heads and the coronary sinus at both time points.
  
  
  RESULTS
  The study population included 34 women (mean age, 29 ± 3 years; body mass index, 24 ± 4 kg/m(2)). The mean gestational age at third-trimester imaging was 237 ± 16 days (34 weeks ± 16 days); the mean number of days for postpartum imaging (baseline) was 107 ± 25 days (16 weeks ± 25 days). There was no statistical difference between the cardiac position at baseline (10.1 ± 1.2 cm) and during the third trimester (10.3 ± 1.1 cm; P = .22).
  
  
  CONCLUSIONS
  Contrary to popular assumption, there is no significant vertical displacement of the heart in the third trimester of pregnancy relative to the nonpregnant state. Accordingly, there is no need to alter hand placement for chest compressions during cardiopulmonary resuscitation in pregnancy.
authors.affiliation: Department of Radiology, College of Medicine, Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada.
authors.forename: Signy
authors.initials: S
authors.lastname: Holmes
authors.affiliation: Department of Radiology, College of Medicine, Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada.
authors.forename: Iain D C
authors.initials: ID
authors.lastname: Kirkpatrick
authors.affiliation: Division of Maternal-Fetal Medicine, The Valley Hospital, Ridgewood, NJ, and Department of Obstetrics and Gynecology, NYU School of Medicine, New York, NY.
authors.forename: Carolyn M
authors.initials: CM
authors.lastname: Zelop
authors.affiliation: Department of Radiology, College of Medicine, Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada; Section of Cardiology, Department of Internal Medicine, College of Medicine, Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada. Electronic address: djassal@sbgh.mb.ca.
authors.forename: Davinder S
authors.initials: DS
authors.lastname: Jassal
mesh_terms: D000293:Adolescent; D000328:Adult; D016887:Cardiopulmonary Resuscitation; D005260:Female; D064368:Healthy Volunteers; D006321:Heart / Q000033:anatomy & histology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D011247:Pregnancy; D011263:Pregnancy Trimester, Third; D011446:Prospective Studies; D055815:Young Adult
keywords: cardiac MRI; pregnancy; resuscitation