Cardiovascular Radiography

Question 1

describe the cardiac silhouette

Answer 1

1. the heart plus the pericardial sac means there is border effacement!!!
   -CANNOT differentiate heart from pericardium on radiographs!!!!!
2. large variation in normal: due to function and breed variation

Question 2

describe the clock face analogy of the cardiac silhouette

Answer 2

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

Question 3

describe atrial location in cats

Answer 3

left atrium is broader and not caudocentral like in dogs; in cats migrates more towards the lateral side

atria are parallel in cats!!!

Question 4

how do you tell left versus right crus of diaphragm?

Answer 4

1. caudal vena cava passes through RIGHT crus (border effacement)
2. on lateral projection, the crus will be more cranial on the side of recumbency (R later = right crus more cranial, etc.)
3. 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!

Question 5

describe cardiovascular interpretation: evaluation of the heart

Answer 5

1. subjectively eval size, shape, margination, and opacity
2. try to ID cardiac margins separately from adjacent fat (esp in cats)
   -careful because fat could make you over-read the margins!
3. 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

Question 6

describe the normal cardiac anatomy of deep chested dogs like dobermans and afghan hounds

Answer 6

1. tall thin hearts
2. upright heart position: little sternal contact, may appear small bc thoracic cavity is so big

Question 7

describe the normal cardiac anatomy of bulldogs

Answer 7

1. wider more rounded silhouette
2. accumulation of fat in cranial mediastinum = wider than deep chested dogs

Question 8

describe cardiac size evaluation in dogs

Answer 8

lateral projection:
2.5-3.5 intercostal spaces wide but BREED variation!!

VD:
1/2 to 2/3 width of the thorax

Question 9

describe vertebral heart scale

Answer 9

in RIGHT lateral projection! (more elongated cardiac silhouette, can see more of apex)

1. length: carina to apex
2. width: perpendicular to length at the widest point at the level of cranial vena cava
3. measure length and width along vertebra starting at T4
4. normal values
   -dogs: 9.7 +/- 0.5; breed variation means up to 12.7 reported as normal in dogs (bulldogs)

Question 10

describe vertebral left atrial size measurement

Answer 10

1. length of the left atrium: carina to caudal vena cava
2. vertebral measurement: starts at cranial portion of T4
3. good correlation with vertebral heart score!
4. normal range:
   1.4-2.2 vertebral bodies
   average: 1.5 vertebral bodies

Question 11

describe modified vertebral left atrial size measurement

Answer 11

1. similar to VLAS plus a perpendicular line at the height of the left atrium
2. vertebral measurement: starts at cranial portion of T4, measure twice and sum up the measurements
3. M-VLAS is superior to vertebral heart score to ID LA enlargement in dogs with MMVD
4. cut off value is at or greater than 3.4 vertebral bodies
   -do not compare measurements between breeds!

Question 12

describe cardiac size eval in cats

Answer 12

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

Question 13

describe feline vertebral heart score

Answer 13

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

Question 14

does the clock face analogy work well in cats?

Answer 14

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)

Question 15

describe cardiac size eval in cats

Answer 15

1. increasing tilt with age; lazy heart, take care when measuring
   -due to supporting ligament laxity, increased sternal contact
2. redundant aorta:
   -aortic knob, found in 30-40% of cats 10-15 years old
   -NOT a cranial mediastinal mass!

Question 16

describe pulmonary vessels

Answer 16

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)

Question 17

what can enlarged pulmonary arteries AND veins indicate?

Answer 17

overcirculation; due to

1. left to right shunting defect
2. atrioventricular fistula
3. overhydration
4. CHF in cats

Question 18

what can just enlarged pulmonary arteries alone indicate?

Answer 18

1. heartworm disease
2. pulmonary hypertension

Question 19

what can just enlarged pulmonary veins alone indicate?

Answer 19

left sided cardiac failure

Question 20

compare and contrast left versus right sided cardiomegaly

Answer 20

left sided: taller silhouette than normal; dorsal displacement of trachea
right sided: wider silhouette than normal

Question 21

describe radiographic signs of left atrial enlargement

Answer 21

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!!

Question 22

describe radiographic signs of left auricular enlargement

Answer 22

1. only seen in cases of at least moderate left auricular enlargement
2. VD/DV: bulge at 2-3 o clock

Question 23

describe radiographic signs of left ventricular enlargement

Answer 23

1. rads not very sensitive for this!
2. left ventricle usually not enlarged alone, also usually see concurrent left atrium
3. lateral projection: elongation of cardiac silhouette (height) with dorsal displacement of the trachea (narrows as runs caudal)
4. VD projection: rounding or blunting of the cardiac apex

Question 24

describe radiographic signs of right sided cardiomegaly

Answer 24

1. 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)

2. lateral projections:
   -widening of cardiac silhouette (>3.5 ICS)
   -increased sternal contact
3. 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)

Question 25

describe focal enlargement of the main pulmonary artery

Answer 25

1. often seen concurrently with enlargement of right side of silhouette (inverted D appearance) 2. on VD: bulge at 1-2:00

Question 26

describe generalized cardiomegaly

Answer 26

1. cardiac and/or pericardial origin 2. cardiac: concurrent left and right cardiomegaly -complet congenital defects -mitral and tricuspid valvular degeneration 3. pericardial: -effusion -PPDH 4. specific bulges CAN be identified

Question 27

describe pericardial effusion

Answer 27

1. GLOBOID cardiac silhouette 2. may develop cardiac tamponade -right sided cardiac failure 3. neoplasia is the most common cause in dogs -right auricular hemangiosarcoma -heart base mass-chemodectoma

Question 28

describe PPDH (peritoneopericardial diaphragmatic hernia)

Answer 28

1. common type of congenitally predisposed hernia 2. opening between peritoneal and pericardial cavities allows abdominal structures to enter the pericardial sac -enlarged cardiac silhouette with mixed opacities 3. often an incidental finding in young dogs and cats

Question 29

describe microcardia

Answer 29

1. less than 2 ICS on lateral projections 2. concurrent small pulmonary vasculature and CVC 3. ddx: -hypoadrenocorticism/Addison's -hypovolemia- most common!

Question 30

describe left versus right sided heart failure in dogs and cats

Answer 30

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

Question 31

describe signs of left-sided congestive heart failure

Answer 31

1. left-sided cardiac enlargement 2. pulmonary VENOUS congestion 3. 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

Question 32

describe signs of right sided CHF

Answer 32

1. hepatic congestion 2. peritoneal effusion 3. pleural effusion

Question 33

review heart failure in cats

Answer 33

1. pulmonary venous +/- arterial enlargement: left 2. pulmonary edema (any distribution): left 3. pleural effusion: left or right 4. peritoneal effusion: right

Question 34

describe differentials for left sided cardiomegaly

Answer 34

1. acquired: -mitral valve degeneration -cardiomyopathy -hypertrophic cardiomyopathy (cats) -endocarditis 2. congenital: -patent ductus arteriosus -sub-aortic stenosis -mitral dysplasia -shunting defects

Question 35

describe differentials for right sided cardiomegaly

Answer 35

1. acquired: -tricuspid valve degeneration -cardiomyopathy -heartworm disease -cor pulmonale (heart issue secondary to a lung issue) 2. congenital: -tricuspid dysplasia -pulmonic stenosis -tetralogy of fallot -shunting defects

Question 36

describe mitral valve degeneration

Answer 36

1. most common cardiac disease in dogs!! -adult small breed dogs 2. 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

Question 37

describe myocardial dysfunction

Answer 37

1. can have decreased contractility and/or myocardial hypertrophy -common in adult large and giant breed dogs and cats 2. 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

Question 38

describe radiographic findings of canine heartworm disease

Answer 38

1. main pulmonary artery bulge -at 1-2:00 2. right sided cardiomegaly 3. dilated and tortuous pulmonary arteries +/- mineralizations 4. bronchial and unstructured interstitial pattern 5. +/- right sided cardiac failure

Question 39

describe patent ductus arteriosus

Answer 39

1. communication of the aorta and MPA -left to right most common (right to left is less common and causes pulmonary hypertension) 2. classic finding: -three knuckles sign: AA, MPA, LAu -ductus diverticulum bulge 3. left sided cardiomegaly 4. pulmonary overcirculation = enlarged veins and arteries

Question 40

describe septal defects

Answer 40

1. initially left to right 2. NO ductus diverticulum enlargement 3. pulmonary overcirculation: enlarged veins and arteries 4. uni or bilteral enlargement and secondary failure 5. ventricular septal defect: most common congenital defect in cats

Question 41

describe pulmonic stenosis

Answer 41

1. enlargement of MPA causes turbulent flow 2. may have small pulmonary arteries and veins (pulmonary undercirculation) 3. right sided cardiomegaly due to right ventricular enlargement 4. if mild, may have normal thoracic radiographs 5. 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

Question 42

describe subaortic stensosis

Answer 42

1. fibrous band at the left ventricle outflow track and/or valvar thickening/hypomotility 2. enlargement of the aortic arch causes turbulent post-stenotic flow 3. left-sided cardiomegaly 4. rad finding: focal enlargement at noon (region of aortic arch)

Question 43

describe mitral/tricuspid valve dysplasia

Answer 43

1. similar findings as mitral or tricuspid valve degeneration 2. enlargement of the left (mitral) and right (tricuspid) side of the heart 3. in young patients! -young dog with tall heart and huge backpack sign -young dog with very wide heart

Question 44

describe tetralogy of fallot

Answer 44

1. pulmonic stensosis, ventricular septal defect, misplaced aorta (to the right), right ventricular hypertrophy 2. rad findings: -boot-shaped heart on VD -pulmonary undercirculation (small pulmonary vessels) 3. pentology of Fallot: -tetralogy + ASD

Question 45

describe cor triatriatum

Answer 45

dexter/sinister/left sided 3 atria (one is blind) causes enlargement of the CVC and peritoneal effusion

Question 46

describe equine thoracic radiography

Answer 46

1. usually 4 different projections in an adult -cranioventral, craniodorsal, caudoventral, and caudodorsal 2. may take both right and left lateral projections -no DV or VD 3. 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 4. echo is the best test