Cardiovascular Radiography Flashcards
describe the cardiac silhouette
- the heart plus the pericardial sac means there is border effacement!!!
-CANNOT differentiate heart from pericardium on radiographs!!!!! - large variation in normal: due to function and breed variation
describe the clock face analogy of the cardiac silhouette
used to ID specific chamber locations
lateral:
12-2:00= left atrium
2-5:00= left ventricle
5-9:00= right ventricle
VD/DV view:
11-1:00= aorta
1-2:00= main pulmonary artery
2-3:00= left auricle
2-5:00= left ventricle
5-9:00= right ventricle
9-11:00= right atrium
left atrium in center just caudal to carina
describe atrial location in cats
left atrium is broader and not caudocentral like in dogs; in cats migrates more towards the lateral side
atria are parallel in cats!!!
how do you tell left versus right crus of diaphragm?
- caudal vena cava passes through RIGHT crus (border effacement)
- on lateral projection, the crus will be more cranial on the side of recumbency (R later = right crus more cranial, etc.)
- if the crus merge at the level of the caudal vena cava = left lateral projection
-in right lateral, the crus are parallel to each other so will not merge together!
describe cardiovascular interpretation: evaluation of the heart
- subjectively eval size, shape, margination, and opacity
- try to ID cardiac margins separately from adjacent fat (esp in cats)
-careful because fat could make you over-read the margins! - cardiac silhouette size and shape inherently variable between species and breeds and between different phases of the cardiac cycle (systole vs. diastole)
ask 3 questions:
1. is heart size normal?
2. is/are there specific chamber enlargement? which ones?
3. is there evidence of heart failure?
-left sided = pulmonary edema
-right sided = pleural effusion, hepatic edema
describe the normal cardiac anatomy of deep chested dogs like dobermans and afghan hounds
- tall thin hearts
- upright heart position: little sternal contact, may appear small bc thoracic cavity is so big
describe the normal cardiac anatomy of bulldogs
- wider more rounded silhouette
- accumulation of fat in cranial mediastinum = wider than deep chested dogs
describe cardiac size evaluation in dogs
lateral projection:
2.5-3.5 intercostal spaces wide but BREED variation!!
VD:
1/2 to 2/3 width of the thorax
describe vertebral heart scale
in RIGHT lateral projection! (more elongated cardiac silhouette, can see more of apex)
- length: carina to apex
- width: perpendicular to length at the widest point at the level of cranial vena cava
- measure length and width along vertebra starting at T4
- normal values
-dogs: 9.7 +/- 0.5; breed variation means up to 12.7 reported as normal in dogs (bulldogs)
describe vertebral left atrial size measurement
- length of the left atrium: carina to caudal vena cava
- vertebral measurement: starts at cranial portion of T4
- good correlation with vertebral heart score!
- normal range:
1.4-2.2 vertebral bodies
average: 1.5 vertebral bodies
describe modified vertebral left atrial size measurement
- similar to VLAS plus a perpendicular line at the height of the left atrium
- vertebral measurement: starts at cranial portion of T4, measure twice and sum up the measurements
- M-VLAS is superior to vertebral heart score to ID LA enlargement in dogs with MMVD
- cut off value is at or greater than 3.4 vertebral bodies
-do not compare measurements between breeds!
describe cardiac size eval in cats
beware! pericardial fat can mimic cardiomegaly
lateral: 2.0-2.5 intercostal spaces wide; measure perpendicular to line linking apex and base because of tilt
VD: 1/2-2/3 width of the thorax
describe feline vertebral heart score
length: tracheal bifurcation to the cardiac apex
width: perpendicular to length, at the widest point
-measure length and width along the vertebrae, starting at T4
VHS: total number of vertebral bodies the lines cover
does the clock face analogy work well in cats?
NO!
determining specific chamber enlargement is difficult, so focus more on shape!
lateral: almond is normal, bell pepper is cardiomegaly
VD/DV: should be almond to oval; valentine shaped heart can indicate enlargement, usually bi-atrial or severe left atrial alone (so cannot tell left versus right sided enlargement just from rads)
describe cardiac size eval in cats
- increasing tilt with age; lazy heart, take care when measuring
-due to supporting ligament laxity, increased sternal contact - redundant aorta:
-aortic knob, found in 30-40% of cats 10-15 years old
-NOT a cranial mediastinal mass!
describe pulmonary vessels
cranial lobar vessels: best visualized on lateral projections (more flattened)
caudal lobar vessels: best visualized on DV!! and VD (more flattened)
size:
-lateral projection: should be approx same as dorsal portion of 4th rib
-VD/DV: cross the 9th or 10th rib, compare at this intersection (should be same or 1.22x the diameter of the rib, or basically NOT bigger than the 10th rib)
-can also compare the sizes of the veins and arteries (should be approx same size)
what can enlarged pulmonary arteries AND veins indicate?
overcirculation; due to
- left to right shunting defect
- atrioventricular fistula
- overhydration
- CHF in cats
what can just enlarged pulmonary arteries alone indicate?
- heartworm disease
- pulmonary hypertension