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.
  • In the forensic context, usually caused by alcoholism.[4]

Microscopic

Features:

  • Epicardial fibrosis.
  • Usually non-specific.

DDx:

  • Mitochondrial myopathy.
    • Perinuclear clearing on light microscopy due to abundant mitochondria.
    • Atypical mitochondria on electron microscopy.
  • Muscular dystrophy.
  • Storage disease.

IHC

Work-up for muscular dystrophy:

  • Dystrophin.

Work-up for mitochondrial disease:

  • COX.
  • SDH.

Hypertrophic cardiomyopathy

  • Abbreviated HCM.

General

  • Genetic.

Gross

  • Classic: septum:left ventricular free wall = 1.5:1.0.[5]

Microscopic

Features:[6]

  • Myocardial fibres have increased transverse size (~40 micrometres) - key feature.
    • Normal myocardial fibre width = 15 micrometres.
  • Haphazard arrangement of myocardial fibres;[7] "basket weave" pattern.
  • Interstitial fibrosis.
    • NOT diffuse patch/area as in an old myocardial infarction.
  • Large hyperchromatic nuclei (~3x fibroblast nucleus).[8]

Notes:

  • Easiest to identify if sections are perpendicular to the long axis of the myocytes.

Images:

Variants

Hypertrophic obstructive cardiomyopathy

  • Abbreviated HOCM.
  • Considered to be a variant of HCM.
  • Historically known as idiopathic hypertrophic subaortic stenosis (IHSS).

Apical HCM

  • AKA Japanese variant.[9]
  • Mid-ventricular septal thickening or apical thickening (NOT subaortic hypertrophy).

Restrictive cardiomyopathy

  • Uncommon form of cardiomyopathy.

Etiology

Multiple causes - an incomplete list:[10]

Arrhythmogenic right ventricular cardiomyopathy

  • Abbreviated ARVC.

General

  • Previously known as "arrhythmogenic right ventricular dysplasia" (abbreviated ARVD).
  • Associated with sudden cardiac death in "young people".[11]
  • Male > female.

Etiology

  • Genetic - mutations in:
    • Desmosomal proteins, especially plakoglobin and desmoplakin.
  • Usually autosomal dominant.
  • Autosomal recessive variant: Naxos syndrome.[12]
    • Clinical: wooly hair, palmar & plantar keratoses.

Microscopic

Features:[13]

  • "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:[13]

  • 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.

Noncompaction cardiomyopathy

Etiology

  • Genetic.[14]
  • May be associated with dilation.[15]
  • Rare.
  • Not clear whether it is a unique entity.[16]

Gross

  • Prominent "mesh-like" trabeculae carnae.
    • Enlarged intertrabecular recesses.[17]

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. ↑ DiMaio, Vincent J.M.; Dana, Suzanna E. (2006). Handbook of Forensic Pathology (2nd ed.). CRC Press. pp. 43. ISBN 978-0849392870.
  5. ↑ JB. 9 June 2011.
  6. ↑ 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.
  7. ↑ DiMaio, Vincent J.M.; Dana, Suzanna E. (2006). Handbook of Forensic Pathology (2nd ed.). CRC Press. pp. 44. ISBN 978-0849392870.
  8. ↑ CK. 14 October 2010.
  9. ↑ Reddy, M.; Thatai, D.; Bernal, J.; Pradhan, J.; Afonso, L. (Jul 2008). "Apical hypertrophic cardiomyopathy: potential utility of Strain imaging.". Eur J Echocardiogr 9 (4): 560-2. doi:10.1016/j.euje.2007.02.004. PMID 17392031.
  10. ↑ DiMaio, Vincent J.M.; Dana, Suzanna E. (2006). Handbook of Forensic Pathology (2nd ed.). CRC Press. pp. 44-5. ISBN 978-0849392870.
  11. ↑ 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.
  12. ↑ http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=601214
  13. ↑ 13.0 13.1 URL: http://emedicine.medscape.com/article/1612324-overview.
  14. ↑ URL: http://www.ncbi.nlm.nih.gov/omim/604169. Accessed on: 19 August 2010.
  15. ↑ URL: http://www.ncbi.nlm.nih.gov/omim/601493. Accessed on: 19 August 2010.
  16. ↑ Paterick TE, Gerber TC, Pradhan SR, Lindor NM, Tajik AJ (2010). "Left ventricular noncompaction cardiomyopathy: what do we know?". Rev Cardiovasc Med 11 (2): 92–9. PMID 20700091.
  17. ↑ Chin TK, Perloff JK, Williams RG, Jue K, Mohrmann R (August 1990). "Isolated noncompaction of left ventricular myocardium. A study of eight cases". Circulation 82 (2): 507–13. PMID 2372897.
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