title: Two-dimensional and M-mode echocardiography of the fetal coronary sinus.
abstract: OBJECTIVE
  To document fetal coronary sinus dimensions in normal pregnancy.
  
  
  METHODS
  Two hundred and sixty-five normal fetuses in which congenital cardiac defects had been excluded were examined cross-sectionally between 21 and 38 weeks of gestation. From the apical or basal four-chamber view the transducer was tilted towards the inferior cardiac surface in order to visualize the coronary sinus by real-time ultrasound. Maximum systolic and diastolic diameters were measured using M-mode. Reference ranges were constructed and the ratio of systolic and diastolic diameters calculated. Data from two fetuses, one with supraventricular tachycardia and a second one with hydrops secondary to anemia, were also compared.
  
  
  RESULTS
  Visualization and measurement of the coronary sinus were successful in 258 (97.4%) patients. The coronary sinus systolic and diastolic diameters increased significantly with gestational age (maximum systolic diameter, 1.6 mm at 21 weeks to 4 mm at 38 weeks; maximum diastolic diameter, 0.9 mm at 20 weeks to 2.2 mm at 38 weeks). The ratio of systolic to diastolic diameters remained relatively constant (range, 1.7-2.1) and therefore was unrelated to gestational age. In the fetuses with supraventricular tachycardia and hydrops, both diameters of the coronary sinus were increased and diminished fluctuation in size during the cardiac cycle was observed.
  
  
  CONCLUSIONS
  The described sonographic approach provides an effective method for measurement of coronary sinus dimensions. The normative data may facilitate the detection of coronary sinus dilation as an indirect marker for abnormalities in venous return to the heart.
authors.affiliation: Center for Advanced Fetal Care, Department of Obstetrics, Gynecology and Reproductive Sciences, University of Maryland, Baltimore 21201-1703, USA.
authors.forename: K C
authors.initials: KC
authors.lastname: Abello
authors.forename: P A
authors.initials: PA
authors.lastname: Stewart
authors.forename: A A
authors.initials: AA
authors.lastname: Baschat
mesh_terms: D003971:Diastole; D005260:Female; D005318:Fetal Heart / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D005865:Gestational Age; D006801:Humans; D011247:Pregnancy; D012016:Reference Values; D013599:Systole; D016216:Ultrasonography, Prenatal