title: Size and shape of right heart chambers in mitral valve regurgitation in small-breed dogs.
abstract: BACKGROUND
  The contribution of right heart (RH) chamber enlargement to general heart enlargement seen on thoracic radiographs in mitral regurgitation (MR) is not known.
  
  
  OBJECTIVE
  To determine the size and shape of the RH chambers in normal dogs and dogs with varying degrees of MR.
  
  
  METHODS
  Fifty-four privately owned dogs: 13 normal, 41 with varying degrees of MR including 25 with congestive heart failure (CHF).
  
  
  METHODS
  Archived first pass radionuclide angiocardiograms were used to produce static images of the RH and left heart (LH) chambers. Indexes of size and shape of the RH and LH chambers were related to severity of MR determined by heart rate-normalized pulmonary transit time (nPTT), vertebral heart scale (VHS), and clinical status. RH shape was measured by a circularity index of RH short axis/long axis.
  
  
  RESULTS
  A 2nd degree polynomial fit best described the ratios; RH/LH dimension to nPTT (R(2)= 0.62) and to VHS (R(2)= 0.43), RH/LH area to nPTT (R(2)= 0.64) and to VHS (R(2)= 0.58), all P < .001. RH circularity was decreased in CHF, P < .001. In CHF, the RH chambers of 16 dogs were both flattened and enlarged, whereas 9 had convex septal borders.
  
  
  CONCLUSIONS
  RH chambers are not significantly dilated in dogs with mild to moderate MR without CHF. In CHF, RH chambers enlarge and also may be compressed by the LH chambers. Pulmonary hypertension probably is present in some dogs with CHF. Increased sternal contact is not a useful sign of right-sided heart dilatation in MR.
authors.affiliation: Section for Diagnostic Imaging, University Animal Hospital, Swedish University of Agricultural Sciences, P.O. Box 7040, SE-750 07 Uppsala, Sweden. carolina.carlsson@uds.slu.se
authors.forename: C
authors.initials: C
authors.lastname: Carlsson
authors.forename: J
authors.initials: J
authors.lastname: Häggström
authors.forename: A
authors.initials: A
authors.lastname: Eriksson
authors.forename: A -K
authors.initials: A-
authors.lastname: Järvinen
authors.forename: C
authors.initials: C
authors.lastname: Kvart
authors.forename: P
authors.initials: P
authors.lastname: Lord
mesh_terms: D000790:Angiocardiography / Q000662:veterinary; D000818:Animals; D006332:Cardiomegaly / Q000473:pathology / Q000662:veterinary*; D004283:Dog Diseases / Q000473:pathology*; D004285:Dogs; D006325:Heart Atria / Q000473:pathology; D006352:Heart Ventricles / Q000473:pathology; D008944:Mitral Valve Insufficiency / Q000473:pathology / Q000662:veterinary*; D012044:Regression Analysis; D012189:Retrospective Studies