Heart
Valvular disease
Degenerative valve disease
Author: R. Amita, M.D.
Topic Completed: 1 September 2014
Minor changes: 31 December 2020
Copyright: 2014-2021, PathologyOutlines.com, Inc.
PubMed Search: Degenerative valve disease [title]
Table of Contents
Definition / general | Terminology | Epidemiology | Sites | Pathophysiology | Diagrams / tables | Etiology | Clinical features | Diagnosis | Radiology description | Prognostic factors | Treatment | Clinical images | Gross description | Gross images | Microscopic (histologic) description | Microscopic (histologic) images | Additional referencesCite this page: Amita R. Degenerative valve disease. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/heartdegenerative.html. Accessed January 20th, 2021.
Definition / general
- Degenerative valve disease occurs due to a pathological weakening / sclerosis of connective tissue
Terminology
- Mitral valve prolapse (MVP), Floppy mitral valve, Flail leaflet, Calcific aortic valve disease
Epidemiology
- Prevalence of degenerative valve disease is estimated at 2 - 3% of the population
Sites
- Mitral and aortic valves
Pathophysiology
- Degenerative mitral valve disease:
- Degeneration occurs in conjunction with an accumulation of dermatan sulfate, a glycosaminoglycan, within the connective tissue matrix of the valve but the exact mechanism is not known
- Calcific aortic valve disease:
- T lymphocytes and macrophages infiltrate endothelium and release cytokines that act on valvular fibroblasts to promote cellular proliferation and extracellular matrix remodeling
- A subset of valvular fibroblasts within fibrosa layer differentiates into myofibroblasts that possess characteristics of smooth muscle cells
- LDL that is taken into the subendothelial layer is oxidatively modified and taken up by macrophages to become foam cells
- ACE is colocalized with apolipoprotein B (ApoB) and facilitates conversion of angiotensin II (AngII), which acts on angiotensin 1 receptors (AT-1R), expressed on valvular myofibroblasts
- A subset of valvular myofibroblasts differentiate into osteoblast phenotype that is capable of promoting calcium nodule and bone formation
Diagrams / tables
Images hosted on other servers:
Potential pathways
MVP subtypes
Etiology
- Occurs with greater frequency in individuals with Ehlers-Danlos Syndrome, Marfan syndrome or polycystic kidney disease
- Other risk factors include Graves disease and chest wall deformities such as pectus excavatum
Clinical features
- Asymptomatic or has a nonspecific clinical presentation
- Mitral valve prolapse:
- For unknown reasons, MVP patients tend to have a low body mass index (BMI) and are typically leaner than individuals without MVP
- May have a syndrome of atypical chest pain, palpitation and dyspnea
- Patients with sudden worsening of the mitral regurgitation owing to chordal rupture or with the onset of atrial fibrillation may have an abrupt onset of dyspnea and exercise intolerance
Diagnosis
- Non ejection systolic click of the mitral valve and a late systolic murmur
Radiology description
- Echocardiography is the most useful method of diagnosing a prolapsed mitral valve
- Two and three dimensional echocardiography are particularly valuable as they allow visualization of the mitral leaflets relative to the mitral annulus
- This allows measurement of the leaflet thickness and their displacement relative to the annulus
Prognostic factors
- MVP is benign, but MVP patients with a murmur, not just an isolated click, have an increased mortality rate of 15 - 20%
- The major predictors of mortality are the severity of mitral regurgitation and the ejection fraction
Treatment
- Symptomatic patients may benefit from beta blockers (e.g., propranolol)
- Patients with prior stroke or atrial fibrillation may require blood thinners such as aspirin or warfarin
- In rare instances, when mitral valve prolapse is associated with severe mitral regurgitation, mitral valve repair or surgical replacement may be necessary
- Mitral valve repair is generally considered preferable to replacement
- Current ACC / AHA guidelines promote repair of mitral valve in patients before symptoms of heart failure develop
- Symptomatic patients, those with evidence of diminished left ventricular function or those with left ventricular dilatation need urgent attention
Clinical images
Images hosted on other servers:
Mitral valve prolapse TEE
Gross description
- Calcific aortic valve disease:
- Characterized pathologically by large nodular calcific masses within the aortic cusps that protrude along the aortic surface into the sinuses of Valsalva, interfering with opening of the cusps
- There is no disease along the ventricular surface
- Degenerative mitral valve disease:
- Two forms of mitral valve disease have been described:
- In the more common, classic form, there are thickened and redundant myxomatous mitral leaflets resulting from abnormal connective tissue
- In the nonclassic form, the prolapsing mitral leaflets are normal in thickness
- Patients with Barlow syndrome have diffuse, generalized thickening and billowing of the leaflets; patients with fibroelastic dysplasia have disease localized to isolated regions of the valve
- The chordae tendineae are frequently elongated and prone to rupture
Gross images
Images hosted on other servers:
Left: minimally diseased aortic valve
Right: severely stenotic aortic valve
Microscopic (histologic) description
- MVP is characterized by myxomatous infiltration, fibroelastic deficiency, collagen alterations, mucopolysaccharide accumulation
- Myxomatous infiltration is characterised by thickening and proliferation of the spongiosa with pooling of glycosaminoglycans
- Spongiosa invades fibrosa giving the appearance of cystic spaces and less dense collagen
- Collagen alterations are characterized by fragmentation of collagenous bundles within the fibrosa
- Elastic fiber alterations are characterized by disrupted, fragmented and granular elastic fibers that form an amorphous clump
- The number of elastic fibers is increased in the abnormal area
Microscopic (histologic) images
Images hosted on other servers:
Calcific aortic valve: Verhoeff-van Gieson stain
