Cardiac Silhouette Flashcards
What is the cardiac silhouette made up of? How does this affect its appearance?
- pericardium, myocardium, epicardium
- cardiac chambers and blood within them
- valves
- great vessels, coronary arteries and veins
all are soft tissue opaque, resulting in border effacement and superimposition
What portions of the heart are highlighted in this radiograph?
What 5 things can affect the size and shape of the cardiac silhouette?
- species
- breed
- respiratory cycle
- cardiac cycle
- positioning - patient obliquity, normal levocardiac position
Variation in cardiac silhouette:
What interface is used to position cardiac anatomy on lateral views? How wide should it be?
clock face —> dogs only
- 12:00-3:00 = LA
- 3:00-5:00 = LV
- 5:00-8:30 = RV
- 8:30-10:00 = RA
- 10:00-12:00 = great vessels
2.5 to 3.5 intercostal spaces
What is the optimal vertebral heart score? What are the 3 steps to measuring it?
10.5x vertebral bodies from T4
- measure from carina to cardiac apex
- measure from cranial to caudal margin at its greatest width
- place these measurements along the spine from the cranial endplate of T4 and count the number of vertebral bodies spanned by both lines
How is the cardiac measurement taken on VD/DV views?
take a measurement at its widest point, which should not be greater than 50% of the pleural-to-pleural diameter at T9
What interface is used to position cardiac anatomy on VD/DV views?
clock face —> dogs only
- 11:00-1:00 = aorta
- 1:00-2:00 = main pulmonary artery
- 2:00-3:00 = left auricular, can bulge with LA enlargement
- 3:00-5:00 = LV
- 5:00-8:30 = RV
- 8:30-11:00 = RA
- LA central
How large should the feline cardiac silhouette be? What is its vertebral heart score like?
2-3 ICS, 60% thoracic height, 45 degrees to the sternum
7-9x vertebral bodies from T4 on right lateral
How is the cardiac silhouette different in obese patients?
subcutaneous fat deposition in sub-pericardium and cranial mediastinum makes it look larger
What is different in this radiograph of a geriatric cat?
- heart is no longer at a 45 degree angle from the sternum = lazy heart position makes it look like its laying on the sternum
- tunica intima and media form a proliferative change secondary to redundant aortic arch at VD
Where is the left atrium visible on a right lateral view? What are 2 indications of its enlargement?
soft tissue opacity caudal to the carina
- dorsal elevation of the trachea and carina
- compression of the left caudal bronchus (particularly on LL) trapped between descending aorta and enlarged LA
How does left atrial enlargement appear on VD/DV views?
left auricle enlargement at the 3:00 position
What are 2 signs of LV enlargement on lateral views?
- straightening of caudal cardiac border
- elongation of the cardiac silhouette
What is evident of LV enlargement on VD/DV views?
rounding of the cardiac silhouette from 3:00-5:00
What is evident of RA enlargement on lateral projections?
rounding of the cranial border of the cardiac silhouette at 9:00-11:00 (right auricle)
What is evident of RA enlargement on VD/DV projections?
rounding of the right lateral border of the cardiac silhouette at 9:00-11:00
(tricuspid valve dysplasia)
What 2 things are seen on lateral projections of RV enlargement? What is especially seen on right lateral projections?
- increased proportion of cardiac silhouette cranial to the carina-apex axis
- dorsal displacement of the trachea
rotation of the apex away from the sternum, which is normally only seen on LL projections
What are 2 signs of RV enlargement on VD/DV projections?
- reverse D sign; curved R side with curved L
- cardiac apex shift to the left
Why is sternal contact not a reliable indicator of right cardiomegaly?
- NOT associated with sternal contact on lateral view
- significant breed variability in the amount of sternal contact
What is the most common cause of generalized cardiomegaly? What are some examples?
pericardial disease caused by right heart failure (pleural effusion, ascites, caudal vena cava enlargement)
- primary tumors: right auricular HSA, heart base chemodectoma
- idiopathic pericardial effusion
- left atrial rupture: chronic mitral valvular degeneration
- peritoneaopericardial diaphragmatic hernia (cats)
- pericarditis
- mitral and tricuspid valve disease
What is occurring in these radiographs?
- enlarged and rounded cardiac silhouette
- confluence between heart and diaphragm
- fat and soft tissue opacity
What shape changes are seen on VD/DV and lateral views in feline cardiomegaly? What causes this?
- VD/DV - “valentine shape” with widening of cardiac silhouette shape
- lateral - changes from “almond” shaped to “jalapeno” shaped
atrial enlargement (can’t distinguish between L and R)
What is the primary etiology of feline cardiomegaly? Other than the heart, what other parts of the CV system are affected?
myocardial disease —> HCM, restrictive cardiomyopathy, heart failure (pleural effusion, pulmonary edema)
pulmonary artery and vein enlargement
Feline cardiomegaly:
- LATERAL: tall and wide silhouette, dorsal trachea, lobular caudal margin (jalapeno shape)
- VD/DV: increased basal shape (valentine shape)
How is pulmonary vasculature observed on radiographs?
evaluate the summation shadow where the caudal lobar pulmonary vessels cross the left and right 9th ribs
- square = normal
- rectangle cranial to caudal = thin (undercirculation)
- rectangle medial to lateral = large (overcirculation)
Where are pulmonary veins seen in comparison to arteries and bronchi?
pulmonary vein = central and ventral
Cranial bronchi:
Caudal bronchi:
How are the sizes of pulmonary veins and arteries observed on lateral projections?
- compare the size of the cranial lobar pulmonary vessels to the width of the 4th ribs proximally
- wider = enlarged
(A and V should be equal in size)
What great vessel anomalies commonly affect the aortic arch, descending aorta, caudal vena cava, and main pulmonary artery?
subaortic stenosis = turbulent flow
ductus diverticulum with L to R flow (PDA) = left sided, 4th ICS, VD/DV
pericardial effusion, other causes of right heart failure
pulmonic stenosis, HW disease, pulmonary hypertension
What is the cause of the anomaly seen in this radiograph?
L to R PDA
- trace descending aorta cranially, should see bulge
What is the cause of the anomaly seen in this radiograph?
subaortic stenosis
- enlarged aorta
What is the cause of the anomaly seen in this radiograph?
pulmonic stenosis
- enlarged RV and pulmonary artery
How does left heart failure present? What are the 4 most common things seen on radiographs?
pulmonary edema
- pulmonary venous enlargement (+ artery in cats)
- unstructured interstitial to alveolar pattern progression
- caudodorsal distribution
- cardiomegaly
What is seen in these feline radiographs?
left CHF
- cardiac silhouette is tall and wide on the lateral projection, causes dorsal displacement of the trachea, and has a valentine appearance on VD
- pleural effusion causing border effacement of the cardiac silhouette and widened fissure lines
- multifocal unstructured interstitial to alveolar pulmonary pattern
- enlarged pulmonary arteries and veins
What is seen in this radiograph?
- enlarged LA and LV
- enlarged pulmonary veins
- enlarged caudal border to the LA and auricle
What are 4 radiographic changes caused by right heart failure?
- pleural effusion
- caudal vena cava enlargement
- hepatomegaly
- ascites
What is cor pulmonale? What are 3 possible causes?
RV enlargement secondary to pulmonary disease that causes pulmonary hypertension, which can lead to right heart failure
- idiopathic pulmonary fibrosis (WHWT)
- chronic mitral valvular degenerative disease
- HW disease
What is seen in this radiograph?
- reverse D appearance with RV enlargement and main pulmonary artery enlargement
- enlarged, tortuous and blunted left caudal lobar pulmonary artery
- pleural effusion (fissures)
How are the 2 types of heart failures differentiated on radiographs?
- LEFT = pulmonary edema (unstructured interstitial to alveolar patterns)
- RIGHT = pleural effusion
What is the pathophysiology to left heart failure?
mitral valvular degenerative disease or acquired cardiac disease causes volume overload in the left atrium and ventricle (+ enlargement) —> pulmonary venous distension —> unstructured interstitial to alveolar pulmonary patterns consistent with pulmonary edema
What is PDA?
abnormal connection (shunt) between descending thoracic aorta and main pulmonary artery, causing blood to flow from the aorta into the pulmonary artery
How does blood flow with PDA?
- volume overload
- main pulmonary artery
- pulmonary arteries
- pulmonary capillaries
- left atrium, left ventricle
- aortic arch, descending aorta at ductus diverticulum due to turbulent flow at the shunt
L 4th ICS —> normal in fetus
What is the most common result of PDA?
left congestive heart failure (pulmonary veins > arteries) and development of pulmonary edema
What is seen in these radiographs?
PDA
- dorsal elevation of trachea
- enlarged LA and LV, pulmonary vasculature (larger than 4th rib)
