Introduction

• Radiology plays an important part in the diagnosis and management of cardiac disease. It allows assessment of the pulmonary vasculature and lungs which is not possible with echocardiology.
• Radiology also plays an important role in the differentiation of cardiac and respiratory cough.

Radiographic considerations

• The radiographic technique is particularly important in thoracic imaging Radiography: thorax.

Positioning

• For the investigation of cardiac disease a right lateral projection  and dorsoventral (DV) projection should be taken.
• Careful positioning is important, particularly to prevent rotation of the thorax which can lead to a false impression of mild left atrial enlargement.
  This effect is most marked in deep chested dogs, eg Doberman pinscher.
• The heart has a complex shape and even small degrees of rotation can make assessment of chamber size unreliable, particularly on the DV projection.

Restraint

• Care must be taken to ensure that the stress of radiography will not cause further decompensation in animals with congestive heart failure.
• Oxygen supplementation via a face mask may help ease the patient's respiratory distress improving the quality of the radiographs.
• A DV projection can usually be taken without sedation in dyspneic animals.
• The lateral projection can then be taken after the patient's condition has been stabilized.
• In most cases, however, it is safer to give a low dose of sedation Sedation / sedative protocols if required than to struggle with a dyspneic animal.
• The intramuscular or intravenous combination of butorphanol Butorphanol and acepromazine Acepromazine maleate ) are generally used in cardiac patients.
  Alpha 2 agonists should be avoided.

Exposure factors

• A high kV low mA technique should be used to reduce contrast within the thorax and allow exposure times to be kept as short as possible.
• Movement blur Radiography: film faults is one of the most common problems in thoracic radiography, particularly in dyspneic patients.
• This can be minimized by using a high kV, dispensing with a grid and using a fast film/screen Radiography: X-ray film combination.

Interpretation

Further Reading

Publications

Refereed papers

• Recent references from PubMed and VetMedResource.
• Gugjoo M B, Hoque M, Saxena A C et al (2013) Vertebral scale system to measure heart size in dogs in thoracic radiographs. Advances in Animal and Veterinary Sciences 1 (1), 1-4 VetMedResource.
• Lamb C R, Wikeley H, Boswood A et al (2001) Use of breed-specific ranges for the vertebral heart scale as an aid to the radiographic diagnosis of cardiac disease in dogs. Vet Rec 148 (23), 707-711 PubMed.
• Sleeper M M & Buchanan J W (2001) Vertebral scale system to measure heart size in growing puppies. JAVMA 219 (1), 57-59 PubMed.
• Buchanan J W & Bücheler J (1995) Vertebral scale system to measure canine heart size on radiographs. JAVMA 206 (2), 194-199 PubMed.