Cardiomyopathy

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Cardiomyopathy, abbreviated as CM, is a domain of cardiology and forensic pathology, as many cardiomyopathies can lead to sudden death.

Overview

Types[1]

  1. Dilated cardiomyopathy - most common ~ 90%
  2. Hypertrophic cardiomyopathy
  3. Restrictive cardiomyopathy - least common

Note: The frequency of the CMs is in alphabetic order dilated, hypertrophic, restrictive.

Dilated cardiomyopathy

General

  • Classic cause of sudden death in young athletes.[2]
  • Most common of the cardiomyopathies.

Causes:

  • Myocarditis - leading cause, usually viral.[3]
  • Familial ~ 30% - can be AD with variable penetrance, AR, X-linked.

Microscopic

Features:

  • Epicardial fibrosis.
  • Usually non-specific.

Hypertrophic cardiomyopathy

General

  • Abbreviated HCM.

Microscopic

Features:[4]

  • Myocardial fibre has increased transverse size (40 micrometres).
    • Normal myocardial fibre width = 15 micrometres.
  • Interstitial fibrosis.

Hypertrophic obstructive cardiomyopathy

  • Considered to be a variant of HCM.

Arrhythmogenic right ventricular cardiomyopathy

General

  • Previously known as "arrhythmogenic right ventricular dysplasia".
  • Associated with sudden cardiac death in "young people".[5]
  • Male > female.

Etiology

  • Genetic - mutations in:
    • Desmosomal proteins, especially plakoglobin and desmoplakin.
  • Usually autosomal dominant.
  • Autosomal recessive variant: Naxos syndrome.[6]
    • Clinical: wooly hair, palmar & plantar keratoses.

Histology

Features:[7]

  • "Moth-eaten" appearance:
    • Loss of myocytes, replaced by:
      • Fat and/or
      • Scar tissue.
  • +/-Inflammation (lymphocytes, macrophages).
  • Myocytes have "bubbly" appearance with loss of myofibres and cross-striations.

Image:

Gross features

Gross:[7]

  • RV wall thinning/replacement with fat.
    • Especially fat where fat is not usually seen - posterior RV wall, RVOT.
  • Septum usually has relative sparing
    • Thus, endomyocardial biopsy is not reliable.
  • +/-Aneurysms/dilation.

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. 601. ISBN 0-7216-0187-1.
  2. ↑ Gojanovic B, Feihl F, Gremion G, Waeber B (February 2007). "[Sudden death in young athletes]" (in German). Praxis (Bern 1994) 96 (6): 189-98. PMID 17330410.
  3. ↑ Luk A, Ahn E, Soor GS, Butany J (March 2009). "Dilated cardiomyopathy: a review". J. Clin. Pathol. 62 (3): 219–25. doi:10.1136/jcp.2008.060731. PMID 19017683.
  4. ↑ 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. 601-3. ISBN 0-7216-0187-1.
  5. ↑ Sudden cardiac death due to hypertrophic cardiomyopathy can be reduced by pre-participation cardiovascular screening in young athletes. URL: http://eurheartj.oxfordjournals.org/cgi/content/full/27/18/2152. Accessed on: 16 December 2009.
  6. ↑ http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=601214
  7. ↑ 7.0 7.1 URL: http://emedicine.medscape.com/article/1612324-overview.
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