Heart valves

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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]

  1. Ventricularis.
    • Elastic tissue.
  2. Spongiosa.
    • Loose connective tissue.
  3. 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.
  • Most common cause of aortic stenosis.

DDx of aortic stenosis:

  1. Calcific aortic stenosis.
  2. Bicuspid aortic valve with calcific aortic stenosis.
  3. Rheumatic heart disease.

Clinical (mnemonic SAD):

  • Syncope.
  • Angina.
  • Dyspnea (shortness of breath) - first symptom.

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.

Localized dystrophic heart valve amyloidosis

General

  • Common:
  • Not seen in acute disease and healed endocarditis.[6]

Hypothesis:

Microscopic

Features:[6]

  • Pink amorphous material - key feature.
    • Usually around the calcific foci.

DDx:

Stains

  • Congo red +ve.

Dystrophic amyloid:[6]

  • Alcian blue -ve.
  • Periodic acid-Schiff -ve.

Myxomatous degeneration

General

Gross

Features:[10]

  • 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.
    • Acid fuchsin, alcian blue, crocein scarlet, elastic hematoxylin, pathology consultation, and saffron.[11][12]

Interpretation of Movat stain:[12]

  • 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.[13]
      • Caused by Streptococcus pyogenes.[14]
  • Disease less frequent today - as streptococcal pharynigits is treated.

Gross

  • "Fish-mouth appearance".
  • Significant valvular thickening.
  • Thickening of the cordae tendinae.

Microscopic

Features:[16]

  • Caterpillar cells (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.
    • Surrounded by lymphocytes (T cells) +/- plasma cells.

Notes:

  • Anitschkow cells are thought to be histocytes and Aschoff bodies are thought to be granulomas.[17]
    • This is disputed.[18]

Images:

IHC

Features (Aschoff bodies & Anitschkow cells):[17]

  • S100 -ve.
  • Muscle specific actin -ve.
  • Desmin -ve.
  • NF -ve.
  • Vimentin +ve.
  • CD45 +ve (weak).

Infective endocarditis

General

  • Infection of the endocardium - often involves the valves (which are covered by endocardium).
  • Before the time of antibiotics -- 100% fatal.

Organisms

Particular organisms are associated with particular clinical scenarios:

  • IV drug user = Staphylococcus aureus.
  • No risk factors/normal valve = Streptococcus viridans.
  • Prosthetic valves = Staphylococcus epidermidis.[19]

Most common organism overall:

  • Staphylococcus aureus.[20]

Clinical

  • Diagnosed (clinically) using the Duke criteria.[21][22]
    • Positive blood cultures.
    • Cardiac involvement - vegetation.
    • +/-Febrile.

Gross

Location:

  • Left sided (mitral, aortic) more common than right sided (pulmonic, tricuspid).
    • This is reversed in IV drug users.[23]

Microscopic

  • Inflammatory infiltrate (key feature @ low power):
    • +/-Plasma cells.
    • +/-Neutrophils.
  • Microorganisms - key feature (diagnostic).
    • Hard to see (even at high power).

Stains

Nonbacterial thrombotic endocarditis

General

  • Abbreviated NBTE.
  • May be associated with catheterization.

Microscopic

Features:

  • No inflammation.
  • No organisms.

Libman-Sacks endocarditis

General

Gross

  • Vegetations anywhere on the valve surface.[24]

Microscopic

Features:

  • Hematoxylin bodies. (???)

Biscupid aortic valve

General

  • Aortic valve usually tricuspid.
  • Most common congenital heart defect.[25]
    • 1-2% of general population.[26]
      • Male:female ~ 2:1.[27]
  • Inherited in autosomal dominant pattern.
    • NOTCH1 gene - implicated.[28]

Significance:

Gross

Features - either:

  1. Raphe does not reach the free margin of the cusp.[29]
  2. No raphe - uncommon (~7% of cases).[30]

Note:

  • Raphe ~ suture or seam.[31]

Images:

Microscopic

Features - section through raphe:

  • "No evidence of fusion."[29]
  • Elastic fibres through-out (not interrupted by fibrous tissue). (???)

Tumours

Main article: Cardiac tumours

Papillary fibroelastomas are the most common tumour of the valve.

See also

References

  1. ↑ 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.
  2. ↑ 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.
  3. ↑ 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.
  4. ↑ Kristen, AV.; Schnabel, PA.; Winter, B.; Helmke, BM.; Longerich, T.; Hardt, S.; Koch, A.; Sack, FU. et al. "High prevalence of amyloid in 150 surgically removed heart valves--a comparison of histological and clinical data reveals a correlation to atheroinflammatory conditions.". Cardiovasc Pathol 19 (4): 228-35. doi:10.1016/j.carpath.2009.04.005. PMID 19502085.
  5. ↑ 5.0 5.1 Falk, E.; Ladefoged, C.; Christensen, HE. (Jan 1981). "Amyloid deposits in calcified aortic valves.". Acta Pathol Microbiol Scand A 89 (1): 23-6. PMID 7223424.
  6. ↑ 6.0 6.1 6.2 6.3 Cooper, JH. (Jul 1983). "Localized dystrophic amyloidosis of heart valves.". Hum Pathol 14 (7): 649-53. PMID 6190729.
  7. ↑ URL: http://emedicine.medscape.com/article/759004-overview. Accessed on: 8 June 2010.
  8. ↑ 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.
  9. ↑ 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.
  10. ↑ 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.
  11. ↑ URL: http://www.mayomedicallaboratories.com/test-catalog/Overview/9832. Accessed on: 8 June 2010.
  12. ↑ 12.0 12.1 Modified Movat's Pentachrome Stain. University Penn Medicine. URL: http://www.med.upenn.edu/mcrc/histology_core/movat.shtml. Accessed on: January 29, 2009.
  13. ↑ 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.
  14. ↑ Chopra, P.; Gulwani, H. (Oct 2007). "Pathology and pathogenesis of rheumatic heart disease.". Indian J Pathol Microbiol 50 (4): 685-97. PMID 18306530.
  15. ↑ URL: http://en.wikipedia.org/wiki/Ellipse. Accessed on: 13 November 2010.
  16. ↑ 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.
  17. ↑ 17.0 17.1 Love, GL.; Restrepo, C. (Jul 1988). "Aschoff bodies of rheumatic carditis are granulomatous lesions of histiocytic origin.". Mod Pathol 1 (4): 256-61. PMID 3070554.
  18. ↑ Stehbens, WE.; Zuccollo, JM. (May 1999). "Anitschkow myocytes or cardiac histiocytes in human hearts.". Pathology 31 (2): 98-101. PMID 10399163.
  19. ↑ Alonso-Valle, H.; Fariñas-Alvarez, C.; García-Palomo, JD.; Bernal, JM.; Martín-Durán, R.; Gutiérrez Díez, JF.; Revuelta, JM.; Fariñas, MC. (Apr 2010). "Clinical course and predictors of death in prosthetic valve endocarditis over a 20-year period.". J Thorac Cardiovasc Surg 139 (4): 887-93. doi:10.1016/j.jtcvs.2009.05.042. PMID 19660339.
  20. ↑ Petti, CA.; Fowler, VG. (Jun 2002). "Staphylococcus aureus bacteremia and endocarditis.". Infect Dis Clin North Am 16 (2): 413-35, x-xi. PMID 12092480.
  21. ↑ http://www.medcalc.com/endocarditis.html
  22. ↑ 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.
  23. ↑ Mathura, KC.; Thapa, N.; Rauniyar, A.; Magar, A.; Gurubacharya, DL.; Karki, DB.. "Injection drug use and tricuspid valve endocarditis.". Kathmandu Univ Med J (KUMJ) 3 (1): 84-6. PMID 16401952.
  24. ↑ 24.0 24.1 Plastiras, SC.; Pamboucas, CA.; Tektonidou, M.; Toumanidis, ST. (Mar 2010). "Real-time three-dimensional echocardiography in evaluating Libman-Sacks vegetations.". Eur J Echocardiogr 11 (2): 184-5. doi:10.1093/ejechocard/jep172. PMID 19946116.
  25. ↑ 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.
  26. ↑ 26.0 26.1 26.2 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.
  27. ↑ Tzemos, N.; Therrien, J.; Yip, J.; Thanassoulis, G.; Tremblay, S.; Jamorski, MT.; Webb, GD.; Siu, SC. (Sep 2008). "Outcomes in adults with bicuspid aortic valves.". JAMA 300 (11): 1317-25. doi:10.1001/jama.300.11.1317. PMID 18799444.
  28. ↑ Garg, V.; Muth, AN.; Ransom, JF.; Schluterman, MK.; Barnes, R.; King, IN.; Grossfeld, PD.; Srivastava, D. (Sep 2005). "Mutations in NOTCH1 cause aortic valve disease.". Nature 437 (7056): 270-4. doi:10.1038/nature03940. PMID 16025100.
  29. ↑ 29.0 29.1 Rose, Alan G. (2008). Atlas of Gross Pathology with Histologic Correlation (1st ed.). Cambridge University Press. pp. 2. ISBN 978-0521868792.
  30. ↑ Sabet, HY.; Edwards, WD.; Tazelaar, HD.; Daly, RC. (Jan 1999). "Congenitally bicuspid aortic valves: a surgical pathology study of 542 cases (1991 through 1996) and a literature review of 2,715 additional cases.". Mayo Clin Proc 74 (1): 14-26. doi:10.4065/74.1.14. PMID 9987528.
  31. ↑ URL: http://dictionary.reference.com/browse/raphe. Accessed on: 25 February 2012.
  32. ↑ Fedak, PW.; Verma, S.; David, TE.; Leask, RL.; Weisel, RD.; Butany, J. (Aug 2002). "Clinical and pathophysiological implications of a bicuspid aortic valve.". Circulation 106 (8): 900-4. PMID 12186790.
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