PS

Question 1

Patterson et al. typical valvular lesions

Answer 1

• Fused valve leaflets w/o thickening
• Dome-shaped valve with central orifice

Question 2

Patterson et al. grade 1 PV dysplasia lesions

Answer 2

• Less common → marked thickening of valve leaflets w/o fusion
  o Grade 1: slight thickening of valve leaflets
   Little/no fusion or hypoplasia
   Minimal or no pulmonary outflow obstruction

Question 3

Patterson et al. grade 2 PV dysplasia lesions

Answer 3

o Grade 2: moderate to severe thickening of valve leaflets
 With fusion or hypoplasia or both
 Moderate to severe pulmonary outflow obstruction

Question 4

Patterson et al. valvular pathology

Answer 4

• PV annulus normal or slightly ↓ size
• Thickening
  o Some degree of thickening in all affected dogs
   Slight thickening
   Bulky, non-flexible, cushion-like leaflets filling valve orifice
  o Equal involvement frequency among 3 leaflets
  o Small irregular nodules on leaflets surface
• Hypoplasia
  o Smaller size leaflet vs normal dog
  o Variable degree from slight reduction to complete absence
   Often mishapen
  o Usually 1 or 2 leaflet involved, most often L involved > anterior > R
• Fusion
  o Adjacent leaflets do not insert separately on intimal surface of PA
  o Variable degree from slight (<1/4) to complete fusion
  o 3 commissures affected w equal frequency

Question 5

Histo of normal PV

Answer 5

o Fibrosa layer on arterial side
 Covered by layer of flat endothelial cells
 May contain elastic fibrils
 Not completely separated from spongiosa
o Spongiosa layer
 Variable thickness
 Loose fibrillar material, fragments of collagen and widely separated cells
o Ventricularis layer on ventricular side
 Fibroelastic layer
 Covered by layer of flat endothelial cells

Question 6

Histo lesions PS

Answer 6

• PS: thickening of spongiosa w loosely arranged collagen tissue
  o Similar cell population

Question 7

Embryology DORV

Answer 7

• Etiology: uncertain
  o Localized growth of trabeculated myocardium early in development
  o RV subdivision/obstruction from arrested incorporation of primitive bulbus cordis into RV body
   Incomplete fusion of bulbar or endocardial cushions → associated VSD

Question 8

gross exam DORV

Answer 8

• Obstructive fibrous band
  o Jct of RV body and proximal infundibulum
  o Below crista supraventricularis
• Anomalous muscle bundles traversing middle of RV: supraventricular crest → RV apex
  o Proximal hypertrophied chamber → sinus portion of RV
  o Distal low pressure chamber → infundibulum portion
• Pyramidal mass of muscle below TV from IVS → RVFW
  o 2 bundles
   Ventral bundle: attach RVFW → IVS
   Dorsal bundle: larger, attach to base of anterior pap muscle
  o Near the base of TV ring (vs moderator band is usually more apical, no obstruction)

Question 9

Types of DORV

Answer 9

o Type I: fibromuscular band of tissue at jct of RV cavity and pulmonary infundibulum (proximal RVOT)
o Type II: fibromuscular thickening of pulmonary infundibulum → just below PV

Question 10

Signalment DORV

Answer 10

asymptomatic animal with heart murmur
o Can also present in R sided CHF

Question 11

PE DORV

Answer 11

loud pansystolic crescendo-decrescendo murmur

Question 12

ECG DORV

Answer 12

• ↑ QRS duration
• R axis deviation
• Junctional tachycardia
• APC/VPCs

Question 13

CTX DORV

Answer 13

• Cardiomegaly, R sided
• Cardiac silhouette can also be normal

Question 14

2D echo DORV

Answer 14

o RVH
o RAE
o Anomalous muscle bundles: muscle proliferation causing obstruction of flow
o Abnormal fluttering of PV

Question 15

Doppler echo DORV

Answer 15

o PG across mid RV: obstruction is proximal to infundibulum
 Vs TOF: obstruction at infundibulum
 Degree of obstruction can vary
o VSD

Question 16

Cardiac KT angio DORV

Answer 16

o Filling defects w/I RV below crista supraventricularis
o VSD

Question 17

Cardiac KT pressure stury DORV

Answer 17

o ↑ pressure in proximal/sinus portion of RV vs lower cavity
o Pressure in distal chamber = PAP
 Unless concommittant PS

Question 18

Natural hx and tx DORV

Answer 18

• Severity increase in time
• Treatment: balloon valvuloplasty, surgical division

Question 19

PS embryology

Answer 19

• Valve development: 3 endocardial swellings → excavation forms cusps

Question 20

Gross exam grading system PS

Answer 20

o Grade 1:
 Slight thickening of PV leaflets w little to no fusion/hypoplasia
 Minimal to no pulmonary OT obstruction

o Grade 2: dysplastic valve
 Moderate/severe thickening of PV leaflets
 Fusion, hypoplasia, dome shaped PV leaflets
 Moderate/severe PV flow obstruction

Question 21

Breeds abn CA PS

Answer 21

o English Bulldogs and Boxers

Question 22

Concurrent defects PS

Answer 22

TVD (large breeds), PFO

Question 23

Histo PS

Answer 23

• Overproduction of normal valve element: 2nd to failure of conversion of embryonic valve primordia
  o Thickening of the valve spongiosa
  o Bands of fusiform 
  o Dense collagen network
• Blood filled spaces lined w endothelium found in cusps

Question 24

Pathophys PS

Answer 24

• ↑ RVOT resistance to blood flow → ↑RV systolic P → RVH
  o Proportional to severity of obstruction
  o Infundibulum hypertrophy → dynamic RVOTO
• Myocardial response to ↑ wall stress
  o Neonatal: hyperplasia + ↑# of capillaries
  o Adult: hypertrophy of existing fibers
• RAE:
  o TR
  o ↑RV filling P
  o ↓ CO → activates RAAS
• RVE: RV failure from
  o ↓ RV SV
  o R-CHF

Question 25

Signalment PS

Answer 25

o Predisposed breeds: Bulldogs, Beagle, Samoyed, Chihuahua, Miniature Schnauzer, Lab, Mastiff, Chow chow, Newfoundland, Basset Hound, Keeshond, WHWT, Terrier, Spaniels  Genetics: heritable in Keeshonds and Beagles o Rare in cats

Question 26

C/s PS

Answer 26

most asymptomatic or o Signs related to ↓ CO: syncope, lethargy o R-sided CHF o Cyanosis if R → L shunting defect

Question 27

PE PS

Answer 27

o Systolic ejection murmur at L base  +/- systolic apical (TR)  +/- diastolic basilar (PI)  +/- pulmonary ejection click → doming of PV  +/- split S2 → ↑ RV ET o Jugular pulse

Question 28

ECG PS

Answer 28

* R axis deviation * Tall/peaked P waves * Transient RBBB following BV reported

Question 29

CTX PS

Answer 29

* MPA dilation * R sided cardiomegaly * Pulmonary underperfusion

Question 30

2D echo PS

Answer 30

o Abnormal PV  Systolic doming  Thickened/fused leaflets w ↓ motion  ↑ echogenicity  Type A (Typical) * Commissural fusion * Normal PA annulus * Aortic:pulmonic ratio of <1.2 * Post stenotic dilation  Type B (Dysplastic) * Dysplastic, immobile leaflets * Narrow annulus/hypoplastic * Aortic:pulmonic ratio of >1.2 o Flattening/paradoxical IVS motion o RVH w prominent pap muscles o Muscular narrowing of RVOT o ↑ endocardium echogenicity (fibrosis) o Post stenotic MPA dilation

Question 31

Dopper echo PS

Answer 31

o High velocity/turbulent flow across stenosis o PG across PV: Mild 30-50mmHg, Moderate 50-80mmHg, Severe >80mmHg o PI: secondary to abnormal valve apparatus and PA annular dilation  Diastolic fluttering of TV  ↑ velocity if PH (>2.5m/s) o TR

Question 32

Cardiac KT angio PS

Answer 32

o Post stenotic dilation of MPA o Features of PV dysplasia  Narrowed valve orifice  Asymmetric valve sinuses  Hypoplasia of annulus/valve sinus  Systolic valve doming  Filling defect → from thickening of leaflets o RVH o Levophase: look for single RCA

Question 33

Cardiac KT pressure study PS

Answer 33

o Systolic PG across obstruction o ↑RV systolic pressure o ↑RAP: ↑a wave

Question 34

Natural hx PS

Answer 34

* PV dysplasia most frequent in dogs o Subvalvular/supravalvular stenosis reported but unfrequent  Supravalvular: Giant Schnauzer o Pulmonary atresia → most severe form * Mild to moderate PS may live normal lives. * Moderate: most dogs are ok, uncertain px long term o PG ↓ might be beneficial if concurrent TVD * Severe may develop c/s and R CHF o General correlation btw PG and survival o Progressive muscular hypertrophy can worsen PG w DRVOTO o Usually balloon valvuloplasty will be attempted to ↓ PG  Single RCA → BV contra indicated, can place stent

Question 35

Decr px PS

Answer 35

when c/s develop o Exercise intolerance o R-CHF o Arrhythmias (Afib)/sudden death

Question 36

Tx PS

Answer 36

o BVP: especially if dysplatic valve w/o hypoplasia o Stent: indicated in CA anomaly of PA hypoplasia  TR: contra indicated since will ↑ RV volume over load w/ creating PI o Sx

Question 37

RVOTO can be associated w/

Answer 37

o HCM o High output states: hyperT4, anemia, fever, pregnancy

Question 38

RVOTO PE

Answer 38

soft early to mid systolic high frequency murmur o Murmur can change with HR and body position

Question 39

Echo DRVOTO

Answer 39

↑ velocity in RVOT o No other cause of murmur on echo and normal heart