Matters of the Heart: Some Tips for Acquiring the Most Effective Cardiac Radiographs
When presented with a coughing or dyspneic dog, a good set of chest films can provide tremendous diagnostic guidance. With radiographic studies, we usually can categorize dyspneic cardiac patients into one of three groups:
- Those with obvious cardiogenic pulmonary edema
- Those in which congestive heart failure can be excluded
- Those who are equivocal for congestive heart failure and may have one of a wide spectrum of pulmonary diseases
Different symptoms, however, require different radiographic views. So, how does your canine patient present?
Recommended views for the best images
For suspected respiratory disease, we often recommend left and right laterals and a ventrodorsal view. For possible cardiac disease, left and right lateral views and a dorsoventral view are often helpful.
Importantly, familiarity with specific views improves diagnostic accuracy. For example:
- My preference for evaluating the cardiac silhouette has become the lateral thorax shot with the patient in left lateral recumbency
- If the pulmonary vasculature is a focus of interest, I prefer visualizing the caudal lung fields from a dorsoventral position, which is often better tolerated than a ventrodorsal position in the dyspneic patient
What different views can reveal
A lateral chest radiograph can reveal indicators of cardiac disease including:
- Loss of the angle between the trachea and spine
- An upright appearance at the caudal border of the cardiac silhouette
- A significant bulge in the area of the left atrium
- Increased vertebral heart size measurement
- Pulmonary venous distention
- Indistinct pulmonary vein margins
- A perihilar or caudodorsal interstitial to alveolar pattern
A dorsoventral view often reveals:
- A left auricular bulge at the 3 o'clock position of the cardiac silhouette
- A double-density sphere between the left and right caudal mainstem bronchi with splaying of the same bronchi
- Compression of the left mainstem bronchus
- Distention of the caudal lobar arteries
- A caudal, medially radiating interstitial pulmonary pattern
When in doubt
If radiographic evaluation still leaves some doubt, we often turn to more advanced imaging, usually echocardiography, which is routinely performed in our office locations or as a mobile service. In some cases, fluoroscopy or a diagnostic drug trial may be helpful.
Bottom line, one size doesn't fit all when it comes to cardiac radiographic views. Suspected pathology combined with experience determines the positioning that will yield the most helpful information in matters of the heart.