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
what can just enlarged pulmonary veins alone indicate?
left sided cardiac failure
compare and contrast left versus right sided cardiomegaly
left sided: taller silhouette than normal; dorsal displacement of trachea
right sided: wider silhouette than normal
describe radiographic signs of left atrial enlargement
lateral projections: backpack sign and straightening of caudal margin of cardiac silhouette
VD/DV: bow legged cowboy sign/focal enlargement of the central portion of silhouette makes path of caudal bronchi curved/displaced
bow legged man could also indicate enlargement of tracheobroncial lymph nodes (but causes ventral displacement), so look at lateral projection for backpack sign to tell if left atrial enlargement (causes dorsal displacement) or not
left atrial enlargement ALONE will NOT cause any dorsal displacement of the trachea!!
describe radiographic signs of left auricular enlargement
- only seen in cases of at least moderate left auricular enlargement
- VD/DV: bulge at 2-3 o clock
describe radiographic signs of left ventricular enlargement
- rads not very sensitive for this!
- left ventricle usually not enlarged alone, also usually see concurrent left atrium
- lateral projection: elongation of cardiac silhouette (height) with dorsal displacement of the trachea (narrows as runs caudal)
- VD projection: rounding or blunting of the cardiac apex
describe radiographic signs of right sided cardiomegaly
- widened cardiac silhouette
-if more cranial: either atrial or auricular
-if more caudal and causing increased sternal contact: more likely ventricular
much harder to interpret with rads, esp if left sided cardiomegaly also present (left sided enlargement can make it look like right sided enlargement)
- lateral projections:
-widening of cardiac silhouette (>3.5 ICS)
-increased sternal contact - VD projection:
-rounding of the right aspect of cardiac silhouette: displacement of cardiac apex to the left
-inverted D appearance (rounded right side and more flattened/straight left side): can lead to overdiagnosis though!
(if tall and wide: either both sides enlarged or left side SUPER enlarged and pushing into right side)
describe focal enlargement of the main pulmonary artery
- often seen concurrently with enlargement of right side of silhouette (inverted D appearance)
- on VD: bulge at 1-2:00
describe generalized cardiomegaly
- cardiac and/or pericardial origin
- cardiac: concurrent left and right cardiomegaly
-complet congenital defects
-mitral and tricuspid valvular degeneration - pericardial:
-effusion
-PPDH - specific bulges CAN be identified
describe pericardial effusion
- GLOBOID cardiac silhouette
- may develop cardiac tamponade
-right sided cardiac failure - neoplasia is the most common cause in dogs
-right auricular hemangiosarcoma
-heart base mass-chemodectoma
describe PPDH (peritoneopericardial diaphragmatic hernia)
- common type of congenitally predisposed hernia
- opening between peritoneal and pericardial cavities allows abdominal structures to enter the pericardial sac
-enlarged cardiac silhouette with mixed opacities - often an incidental finding in young dogs and cats
describe microcardia
- less than 2 ICS on lateral projections
- concurrent small pulmonary vasculature and CVC
- ddx:
-hypoadrenocorticism/Addison’s
-hypovolemia- most common!
describe left versus right sided heart failure in dogs and cats
dogs:
left sided: pulmonary edema only
right sided: no pulmonary edema, but will see pleural effusion, peritoneal effusion, and pericardial effusion
cats:
left sided: pulmonary edema and pleural effusion
right sided: no pulmonary edema, but will see pleural effusion, peritoneal effusion, and pericardial effusion
describe signs of left-sided congestive heart failure
- left-sided cardiac enlargement
- pulmonary VENOUS congestion
- cardiogenic pulmonary edema (increased opacity of lungs/unstructured interstitial to alveolar pattern)
-perihilar and caudodorsal distribution in cases of mitral valve insufficiency
in cats!
1. pleural effusion
2. pulmonary edema: wherever it wants
3. no need for cardiomegaly to have left-sided CHF; if see pleural effusion and pulmonary edema, most likely left sided CHF even if not cardiomegaly
describe signs of right sided CHF
- hepatic congestion
- peritoneal effusion
- pleural effusion
review heart failure in cats
- pulmonary venous +/- arterial enlargement: left
- pulmonary edema (any distribution): left
- pleural effusion: left or right
- peritoneal effusion: right
describe differentials for left sided cardiomegaly
- acquired:
-mitral valve degeneration
-cardiomyopathy
-hypertrophic cardiomyopathy (cats)
-endocarditis - congenital:
-patent ductus arteriosus
-sub-aortic stenosis
-mitral dysplasia
-shunting defects
describe differentials for right sided cardiomegaly
- acquired:
-tricuspid valve degeneration
-cardiomyopathy
-heartworm disease
-cor pulmonale (heart issue secondary to a lung issue) - congenital:
-tricuspid dysplasia
-pulmonic stenosis
-tetralogy of fallot
-shunting defects
describe mitral valve degeneration
- most common cardiac disease in dogs!!
-adult small breed dogs - rad findings:
-enlargement of left side of the heart: initially left atrium and left auricle, later left ventricle
-dilated pulmonary veins: congestion
-leads to left sided heart failure: cardiogenic edema
describe myocardial dysfunction
- can have decreased contractility and/or myocardial hypertrophy
-common in adult large and giant breed dogs and cats - rad findings:
-left atrium enlargement
– +/- enlargement of the left ventricle and right sided chambers depending on pathophys
-dilated pulmonary veins: congestion
-leads to left sided heart failure: cardiogenic edema
describe radiographic findings of canine heartworm disease
- main pulmonary artery bulge
-at 1-2:00 - right sided cardiomegaly
- dilated and tortuous pulmonary arteries +/- mineralizations
- bronchial and unstructured interstitial pattern
- +/- right sided cardiac failure
describe patent ductus arteriosus
- communication of the aorta and MPA
-left to right most common (right to left is less common and causes pulmonary hypertension) - classic finding:
-three knuckles sign: AA, MPA, LAu
-ductus diverticulum bulge - left sided cardiomegaly
- pulmonary overcirculation = enlarged veins and arteries
describe septal defects
- initially left to right
- NO ductus diverticulum enlargement
- pulmonary overcirculation: enlarged veins and arteries
- uni or bilteral enlargement and secondary failure
- ventricular septal defect: most common congenital defect in cats
describe pulmonic stenosis
- enlargement of MPA causes turbulent flow
- may have small pulmonary arteries and veins (pulmonary undercirculation)
- right sided cardiomegaly due to right ventricular enlargement
- if mild, may have normal thoracic radiographs
- MUST do fluoroscopy before treating because if have R2A abnormality where left coronary wraps around pulmonic trunk, the treatment of balloon valvuloplasty could rupture the left coronary
describe subaortic stensosis
- fibrous band at the left ventricle outflow track and/or valvar thickening/hypomotility
- enlargement of the aortic arch causes turbulent post-stenotic flow
- left-sided cardiomegaly
- rad finding: focal enlargement at noon (region of aortic arch)
describe mitral/tricuspid valve dysplasia
- similar findings as mitral or tricuspid valve degeneration
- enlargement of the left (mitral) and right (tricuspid) side of the heart
- in young patients!
-young dog with tall heart and huge backpack sign
-young dog with very wide heart
describe tetralogy of fallot
- pulmonic stensosis, ventricular septal defect, misplaced aorta (to the right), right ventricular hypertrophy
- rad findings:
-boot-shaped heart on VD
-pulmonary undercirculation (small pulmonary vessels) - pentology of Fallot:
-tetralogy + ASD
describe cor triatriatum
dexter/sinister/left sided 3 atria (one is blind) causes enlargement of the CVC and peritoneal effusion
describe equine thoracic radiography
- usually 4 different projections in an adult
-cranioventral, craniodorsal, caudoventral, and caudodorsal
- may take both right and left lateral projections
-no DV or VD - determination of cardiac size is difficult
-lack of objective criteria and inability to obtain orthogonal views
-enlargement may be seen as: straightening of caudal aspect of heart, increased sternal contact and diaphragmatic contact, and dorsal displaced trachea - echo is the best test
