Difference between revisions of "Heart valves"
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==Normal histology== | ==Normal histology== | ||
===Aortic valve=== | ===Aortic valve=== | ||
General | General: | ||
* | *Covered by endothelium. | ||
* | *Mostly avascular (nutrients supplied by diffusion). | ||
Terminology | Terminology: | ||
* | *Base - closest to the aortic wall. | ||
* | *Free edge - closest to the centre of the valve/interacts with other valve cusps. | ||
Three layers (from proximal (ventricular side) to distal (valsalva side)):<ref>PBoD P.558.</ref> | Three layers (from proximal (ventricular side) to distal (valsalva side)):<ref>PBoD P.558.</ref> | ||
| Line 57: | Line 57: | ||
===Mitral valve=== | ===Mitral valve=== | ||
===Gross=== | ===Gross=== | ||
*Cordae tendinae | *Cordae tendinae. | ||
===Histology=== | ===Histology=== | ||
Revision as of 19:11, 13 May 2010
Heart valves are the domain of the cardiac surgeon and their bread & butter.
Clinical
General
- Insufficiency (regurgitant flow) - murmur in diastole.
- Stenosis (decreased flow area) - murmur in systole.
Pathology
Which valves cause the most trouble?
- Mostly those on the left side (subjected to higher pressures), i.e. mitral valve (or left atrioventricular v.) and aortic valve.
Aortic stenosis - cause?
- Mostly "calcific aortic stenosis".
Quick approach to valves
Gross
- Calcification?
- Consider calcific stenosis.
- Vegetations?
- Consider infective endocarditis.
- Thin?
- Consider myxomatous change.
Microscopic
- Inflammation?
- Consider endocarditis.
- Anitschkow's cells (caterpillar cells)?
- Rheumatic heart disease.
- Aschoff bodies?
- Rheumatic heart disease.
- Thickening of spongiosa (layer)?
- Myxomatous change?
Normal histology
Aortic valve
General:
- Covered by endothelium.
- Mostly avascular (nutrients supplied by diffusion).
Terminology:
- Base - closest to the aortic wall.
- Free edge - closest to the centre of the valve/interacts with other valve cusps.
Three layers (from proximal (ventricular side) to distal (valsalva side)):[1]
- Ventricularis.
- Elastic tissue.
- Spongiosa.
- Loose connective tissue.
- Fibrosa.
- Mostly collagen, thickest part in a normal valve.
Mitral valve
Gross
- Cordae tendinae.
Histology
- Similar to the aortic valve.
Calcific aortic stenosis
General
- Somewhat similar to atherosclerosis; however, considered a separate entity[2]
- Mitral valve is usually normal.
Micro
Features:[3]
- Affects the valsalva side of the valve.
- It affects the fibrosa.
- Primarily at the base of the valve, i.e. there is relative sparing the free edge.
Myxomatous degeneration
General
- Usually affects the mitral valve.
- Female > male,[4] disputed by Toronto data.[5]
- Associated with Marfan's syndrome and Turner's syndrome.[6]
Gross
Features[7]
- No commissural fusion.
- Commissural fusion typical of rheumatic heart disease.
- Thickened.
- Rubbery consistency.
- Reactive/secondary changes.
- Fibrosis due to prolapse/abnormal contact of valve with other structures.
- Clots/organized thrombus - due to stasis.
Microscopic
- Thinning of fibrosa layer.
- Thickening of spongiosa layer with mucoid (myxomatous) material. (key feature).
- +/-Secondary changes (due to valvular dysfunction): thrombi, fibrosis.
Staining
- Movat stain.
Interpretation of Movat stain:[9]
- black = nuclei and elastic fibers.
- yellow = collagen and reticular fibers.
- blue = mucin, ground substance.
- red (intense) = fibrin.
- red = muscle.
Rheumatic heart disease
General
- Classically leads to mitral valve stenosis.
- Rheumatic fever accounts for 99% of mitral stenosis[10]
- Disease less frequent today - as streptococcal pharynigits is treated.
Gross
- "Fish-mouth appearance".
- Slit-like morphology; ellipical cross-sectional flow area (mitral valve) has an abnormally small semi-minor axis[11] axis due to valve thickening.
- Image: Fish-mouth appearance (pipe) - principia-eng.com.
- Significant valvular thickening.
- Thickening of the cordae tendinae.
- Images:
Microscopic
Features:[12]
- Caterpillar cell (aka Anitschkow cells)
- Abundant eosinophilic cytoplasm.
- Moderately-poorly defined cell border.
- Well-defined central ovoid nucleus with a prominent wavy ribbon-like chromatin -- looks vaguely like a caterpillar with some immagination.
- Pathognomonic for rheumatic fever.
- Aschoff bodies:
- Usually in the heart itself,
- Jumbled collagen, eosinophilic, and
- Surrounded by lymphocytes (T cells) +/- plasma cells.
Images:
Endocarditis
General
- Infection of the endocardium - often involves the valves (which are covered by endocardium).
- Before the time of antibiotics -- 100% fatal.
Clinical
- Diagnosed (clinically) using the Duke criteria.[13][14]
- positive blood cultures.
- cardiac involvement - vegetation.
- +/-febrile.
Microscopic
- Inflammatory infiltrate (key feature @ low power)
- +/-Plasma cells,
- +/-Neutrophils.
- Microorganisms (key feature - diagnostic)
- Hard to see (even at high power).
Stains
- GMS (Gomori Methenamine-silver stain)
- look for fungi.
- Gram stain
- look for bacteria.
Biscupid aortic valve
General
- Aortic valve usually tricuspid.
- 1-2% of general population.[15]
- Inherited in autosomal dominant pattern.
Significance
- Associated with ascending aortic aneurysms - x10 risk of dissection vs. normal population[15]
- 30% develop serious morbidity.[15]
- Associated with early development of calcific aortic stenosis.
Tumours
Main article: Cardiac tumours
Papillary fibroelastomas are the most common tumour of the valve.
See also
References
- ↑ PBoD P.558.
- ↑ Otto CM (September 2008). "Calcific aortic stenosis--time to look more closely at the valve". N. Engl. J. Med. 359 (13): 1395-8. doi:10.1056/NEJMe0807001. PMID 18815402.
- ↑ PBoD P.590
- ↑ [1]
- ↑ Leong SW, Soor GS, Butany J, Henry J, Thangaroopan M, Leask RL (October 2006). "Morphological findings in 192 surgically excised native mitral valves". Can J Cardiol 22 (12): 1055-61. PMID 17036100.
- ↑ Wigle ED, Rakowski H, Ranganathan N, Silver MC (1976). "Mitral valve prolapse". Annu. Rev. Med. 27: 165–80. doi:10.1146/annurev.me.27.020176.001121. PMID 779595.
- ↑ PBoD P.591.
- ↑ [2]
- ↑ 9.0 9.1 Modified Movat's Pentachrome Stain. University Penn Medicine. URL: http://www.med.upenn.edu/mcrc/histology_core/movat.shtml. Accessed on: January 29, 2009.
- ↑ PBoD P.594.
- ↑ http://en.wikipedia.org/wiki/Ellipse
- ↑ PBoD P.593.
- ↑ http://www.medcalc.com/endocarditis.html
- ↑ Durack DT, Lukes AS, Bright DK (March 1994). "New criteria for diagnosis of infective endocarditis: utilization of specific echocardiographic findings. Duke Endocarditis Service". Am. J. Med. 96 (3): 200-9. PMID 8154507.
- ↑ 15.0 15.1 15.2 Vallely MP, Semsarian C, Bannon PG (October 2008). "Management of the ascending aorta in patients with bicuspid aortic valve disease". Heart Lung Circ 17 (5): 357-63. doi:10.1016/j.hlc.2008.01.007. PMID 18514024.