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