Heart valves
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 (see-through)?
- 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.
Notes:
- The loading of the ventricular aspect is tensile and the valsalva side compressive. Thus, it makes sense that the tissue on the ventricular aspect is good in tensile loading and the tissue on the valsalva side good in compression. The elastic tissue can be thought of as rebar... the collagen as concrete.
Mitral valve
Gross
- Cordae tendinae.
- Should be thin.
- No fusion.
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.
Microscopic
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 syndrome (Monosomy X).[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.
Image:
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; elliptical 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 imagination.
- 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 stain (Gomori Methenamine-silver stain).
- Look for fungi.
- Gram stain.
- Look for bacteria.
Non-bacterial thrombotic endocarditis
General
- Abbreviated NBTE.
- May be associated with catheterization.
Microscopic
Features:
- No inflammation.
- No organisms.
Libman-Sacks endocarditis
General
- Associated with systemic lupus erythematosus.[15]
Gross
- Vegetation. (???)
Microscopic
Features:
- Hematoxylin bodies. (???)
Biscupid aortic valve
General
- Aortic valve usually tricuspid.
- 1-2% of general population.[16]
- Inherited in autosomal dominant pattern.
- Most common congenital heart defect.[17]
Significance
- Associated with ascending aortic aneurysms - x10 risk of dissection vs. normal population.[16]
- 30% develop serious morbidity.[16]
- 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
- ↑ Cotran, Ramzi S.; Kumar, Vinay; Fausto, Nelson; Nelso Fausto; Robbins, Stanley L.; Abbas, Abul K. (2005). Robbins and Cotran pathologic basis of disease (7th ed.). St. Louis, Mo: Elsevier Saunders. pp. 558. ISBN 0-7216-0187-1.
- ↑ 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.
- ↑ Cotran, Ramzi S.; Kumar, Vinay; Fausto, Nelson; Nelso Fausto; Robbins, Stanley L.; Abbas, Abul K. (2005). Robbins and Cotran pathologic basis of disease (7th ed.). St. Louis, Mo: Elsevier Saunders. pp. 590. ISBN 0-7216-0187-1.
- ↑ URL: http://emedicine.medscape.com/article/759004-overview. Accessed on: 8 June 2010.
- ↑ 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.
- ↑ Cotran, Ramzi S.; Kumar, Vinay; Fausto, Nelson; Nelso Fausto; Robbins, Stanley L.; Abbas, Abul K. (2005). Robbins and Cotran pathologic basis of disease (7th ed.). St. Louis, Mo: Elsevier Saunders. pp. 591. ISBN 0-7216-0187-1.
- ↑ URL: http://www.mayomedicallaboratories.com/test-catalog/Overview/9832. Accessed on: 8 June 2010.
- ↑ 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.
- ↑ Cotran, Ramzi S.; Kumar, Vinay; Fausto, Nelson; Nelso Fausto; Robbins, Stanley L.; Abbas, Abul K. (2005). Robbins and Cotran pathologic basis of disease (7th ed.). St. Louis, Mo: Elsevier Saunders. pp. 594. ISBN 0-7216-0187-1.
- ↑ URL: http://en.wikipedia.org/wiki/Ellipse. Accessed on: 13 November 2010.
- ↑ Cotran, Ramzi S.; Kumar, Vinay; Fausto, Nelson; Nelso Fausto; Robbins, Stanley L.; Abbas, Abul K. (2005). Robbins and Cotran pathologic basis of disease (7th ed.). St. Louis, Mo: Elsevier Saunders. pp. 593. ISBN 0-7216-0187-1.
- ↑ 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.
- ↑ URL: http://dictionary.reference.com/browse/libman-sacks+endocarditis. Accessed on: 24 May 2011.
- ↑ 16.0 16.1 16.2 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.
- ↑ Siu SC, Silversides CK (June 2010). "Bicuspid aortic valve disease". J. Am. Coll. Cardiol. 55 (25): 2789–800. doi:10.1016/j.jacc.2009.12.068. PMID 20579534.