title: Cardinal vein isomerism: an embryological hypothesis to explain a persistent left superior vena cava draining into the roof of the left atrium in the absence of coronary sinus and atrial septal defect.
abstract: BACKGROUND
  A persistent left superior vena cava (PLSVC) is a relatively frequent systemic venous anomaly associated with congenital heart defects. This anomaly has been explained with the persistence of the left superior cardinal vein. PLSVC usually drains into the right atrium, via coronary sinus, but it joins the left atrium in approximately 8% of the cases either directly in the setting of atrial isomerism, or via an unroofed coronary sinus, or through a coronary sinus type atrial septal defect.
  
  
  METHODS
  We describe a case of an adult patient with atria in the situs solitus, PLSVC draining into the left atrium, atresia of coronary sinus without atrial septal defect, and with additional cardiac anomalies (ventricular septal defect and discrete subaortic stenosis).
  
  
  CONCLUSIONS
  A possible embryological explanation to this case rises from a right partial isomerism of the superior cardinal veins, which gives reason for both the coexistence of the PLSVC draining into the left atrium and the absence of coronary sinus, atrial septal defect, or coronary sinus ostium.
authors.affiliation: Institute of Cardiac Surgery, La Sapienza University, Rome, Italy. fabiomiraldi@hotmail.com
authors.forename: Fabio
authors.initials: F
authors.lastname: Miraldi
authors.forename: Cira R T
authors.initials: CR
authors.lastname: di Gioia
authors.forename: Piero
authors.initials: P
authors.lastname: Proietti
authors.forename: Marcello
authors.initials: M
authors.lastname: De Santis
authors.forename: Giulia
authors.initials: G
authors.lastname: d'Amati
authors.forename: Pietro
authors.initials: P
authors.lastname: Gallo
mesh_terms: D000328:Adult; D003330:Coronary Vessel Anomalies / Q000473:pathology*; D005260:Female; D006325:Heart Atria / Q000002:abnormalities*; D006344:Heart Septal Defects, Atrial / Q000473:pathology* / Q000601:surgery; D006801:Humans; D018810:Magnetic Resonance Angiography; D016896:Treatment Outcome; D014683:Vena Cava, Superior / Q000002:abnormalities*