Mitral Valve Pathology

Question 1

Primary mitral valve prolapse results from…

Answer 1

myxomatous proliferation of the leaflets.

Question 2

Describe the findings of myxomatous mitral valve disease.

Answer 2

• “Thick and redundant”
• Thickening occur across the entire valve, including leaflets and chordae tendinae
• Due to accumulation of mucopolysaccharides, with prominence of the spongiosa layer of the leaflets.
• Impaired tensile strength is more marked in the chordae than the leaflets.
• Chordae elongation results in prolapse and loss of leaflet coaptation and may cause MR.

Question 3

What is the measurement used to describe classic MVP?

Answer 3

Diffuse leaflet thickening of > or equal to 5mm

Question 4

What are the two subtypes of myxomatous MV disease?

Answer 4

Barlow disease – seen in younger patients, shows greater annular dilation, more marked leaflet redundancy and prolapse that involves multiple segments

Fibroelastic deficiency – occurs in older patients, typically confined to the posterior middle scallop (P2), associated with thinning and rupture of chordae.

Question 5

Describe genetics of primary MVP

Answer 5

• Higher prevalence of MVP among family member of those affected
• Autosomal dominant mode of inheritance with variable penetrance
• Linkage to a site on chromosome 16 (in some families)

Question 6

What other CTDs are associated with MVP?

Answer 6

Marfan
Ehler-Danlos
Pseudoxanthoma elasticum
Myotonic dystrophy

Question 7

What is the most common group to suffer severe MR from MVP?

Answer 7

-Men in sixth decade of life with primary prolapse

Question 8

What is the phenotypic description involved in secondary prolapse?

Answer 8

• Relatively normal valvular structure

- Disproportion between leaflet size and LV cavity size produces mechanical forces that may lead to leaflet prolapse

Question 9

What is the most common group affected by secondary prolapse?

**Secondary prolapse is usually of little clinical significance and is not usually associated with significant MR.

Answer 9

• Younger women
• Normalization of the relative disproportion between leaflet size and cavity size often occurs with aging; thus incidence decreases with age

Question 10

What other conditions are associated with secondary prolapse?

Answer 10

ASD
Hyperthyroidism
Emphysema
Hypertrophic cardiomyopathy