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What abnormalities of the great vessels might be identified by routine radiography?

Radiography is a simple means to determine changes in the great vessels.

  • Distention of the aorta in the region of the aortic arch with aortic stenosis:
    • may not be apparent unless aortic stenosis (or subaortic) is severe
  • Dilation of the main pulmonary artery (MPA):
    • due to pulmonic stenosis, heartworm disease, or pulmonary artery hypertension
  • Pulmonary over-circulation:
    • left to right shunt
  • Pulmonary under-circulation:
    • right to left shunt
    • under-perfusion/hypovolemia/dehydration
  • Caudal vena caval enlargement:
    • Caudal vena cava Present if the caudal vena cava is persistently of greater diameter than the descending thoracic aorta on the lateral view (normally they are roughly equal).
    • Suggests right heart failure with elevated volumes in the caudal vena cava.

What radiographic features might suggest the presence of heartworm disease?

  • Right ventricular enlargement
  • Dilation of main pulmonary artery (MPA)
  • Tortuosity of pulmonary arteries (PAs)
  • Truncated PAs
  • Enlargement of PAs

Can radiography diagnose pericardial effusion?

Radiography is useful to suggest a diagnosis of pericardial effusion.

  • A very rounded (globose) enlarged heart is present; individual chambers cannot be visualized
  • Pleural effusion is common (therefore, obscures the cardiac silhouette), ascites is common
  • Pulmonary edema is usually absent, however pleural effusion obscures our ability to visualize the features of pulmonary edema.