Cardio/mediastinal radiographs Flashcards
what is VHS? what is the mean?
used to evaluate cardiac size, compares heart to mid-thoracic vertebrae (ID enlargement, monitoring change)
place length of both short and long axes along vertebrae, starting at T4 and going caudally. number of vertebrae along measurement (add together short and long axes) –> VHS
mean: 9.7 ± 0.5 (dogs), <8 (cats)
short axis: middle 3rd of heart (incl. R atrium & L chambers)
long axis: tracheal carina to cardiac apex (incl. L atrium + ventricle)
what are the 25-50-25 and the 2/3:1/3 rules?
25-50-25: in VD/DV view, heart should be 50% of mediastinum, and the L and R space between body wall and heart should each be 25%
2/3:1/3: in lateral view, heart should be 2/3 of mediastinum, and there should be 1/3 of space above heart to body wall
what is hypertrophy vs dilation in the context of radiography?
hypertrophy: maintains overall vol w/ loss of luminal vol (increase wall thickness) – difficult to visualize
dilation: increases overall vol v/ increase in intraluminal vol, similar to decreased wall thickness – visible radiographically
left-sided cardiac enlargement – what conditions cause this?
myxomatous mitral valve disease (most common!)
aortic stenosis
hypertrophic cardiomyopathy
restrictive cardiomyopathy
patent ductus arteriosus
ventricular septal defect
how can you see left ventricular cardiac enlargement on radiograph?
lateral view: “taller” heart, rounding of L ventricular border, dorsal elevation of trachea
VD: “taller” heart, difficult to evaluate
how can you see left atrial/auricular cardiac enlargement in radiograph?
lateral: loss of cardiac waist, rounding of atrial border
VD: auricle often displaced laterally by enlarged atrium, atrium causes lat. displacement of primary bronchi
how can you see right sided cardiac enlargement on radiograph?
widened heart on DV/VD, rounding of right ventricular border, increased sternal contact (variable w/ breed/species)
what conditions cause right sided cardiac enlargement?
pulmonic stenosis
tricuspid dysplasia
heartworm
pulmonary hypertension
tell me about looking at pulmonary vessels sizes on radiographs and what they mean
V>A: venous hypertension –> mitral valve disease
A >V: pulmonary hypertension –> heartworm, pulmonary fibrosis
A&V increase: shunt (L to R), fluid overload, fluid retention
A&V decrease: dehydration, decrease right ventricle output
what does a globoid heart mean on radiograph? what are the ddx’s?
generalized cardiac enlargement
pericardial effusion, DCM, end-stage mitral valve disease
you have a patient with potential heart failure. What should you do to assess?
consider DV view, corroborate with 2 views (if only on 1, then likely not edema)
right-sided HF: pleural effusion present
left-sided HF: pulmonary edema present, perihilar distribution, tends to be patchy alveolar to interstitial patterns - look at vessels, should be enlarged (may not be if treated)
the above is for dogs only
what is pectus excavatum?
sternum sunken into chest, commonly incidental
thoracic masses – origin? how to discern from pulmonary masses?
often rib origin (chondrosarcoma, osteosarcoma)
difficult to differentiate from pulmonary masses
but! can use extra pleural signs – well-circumscribed, cranial and caudal edges taper to thoracic wall rather than circular appearance of pulmonary mass
tell me about visibility of pleural space on radiographs
not usually visible bc silhouetting with adjacent ST
if tangential, may become mildly apparent
if widened with other ST/fluid in b/t, may become visible
if thickened (age, pleuritis)
fissure lines indicate pleura
when should you examine the pleural space on radiograph? what are the 3 main categories of disease?
dyspnea, thoracic distension, asynchronous breathing, muffled heart sounds on auscultation
pleural effusion
pneumothorax
diaphragmatic hernia
what does pleural effusion look like on radiograph? what do these signs depend on? what positioning?
fluid opacity in pleural space, retraction and rounding of lung lobes, scalloping, effacement of heart/diaphragm, widening pleural space filled with fluid
depend on vol of fluid (100ml needed to see widening of pleural fisures)
VD more sensitive (fluid accumulates dorsally, lungs retract better, but more dangerous for patient)
(DV safer for patient, but fluid accumulates ventrally and silhouettes the heart)
if pleural effusion is severe and effacing all thoracic contents what should you do?
thoracocentesis to drain and then re-take images
tell me about the categories of pneumothorax
open: free passage of air from environment
closed: air leakage from lungs, trachea, bronchi, esophagus, mediastinum
tension: valve effect, air drawn in doesn’t escape
normotensive: pleural pressure is same as atm
what are the radiographic signs of pneumothorax?
gas in pleural space, retraction of lung lobes (truncated normal pulmonary vasculature), elevation of cardiac silhouette
tension pneumothorax – is it serious? what does it cause radiographically?
emergency!
displacement of lung and mediastinal shift away from side of tension pneumothorax
what is included in the cranial, middle, and caudal mediastinum?
cranial: great vessels, esophagus, trachea, lymph nodes, thymus, fat
middle: heart
caudal: esophagus, aorta, vena cava
tell me about the normal proportions of the cranial mediastinum
normal thickness is apex 2x width of vertebral bodies in dogs, 1x in cats
variation w/I breed and BCS
what are the 4 general classifications of mediastinal abnormalities?
mediastinal shift
mediastinal masses
mediastinal fluid
pneumomediastinum
what is mediastinal shift? what are the causes? how to evaluate/views?
deviation of mediastinal structures towards 1 side of the chest cavity
causes: unilateral increase/decrease in lung vol, presence of intrathoracic mass with secondary deviation
best evaluated on VD and DV
