Difference between revisions of "Myocardial infarction"

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#redirect [[Heart#Myocardial infarction]]
{{ Infobox diagnosis
| Name      = {{PAGENAME}}
| Image      = MI_with_contraction_bands_very_high_mag.jpg
| Width      =
| Caption    = Contraction band necrosis - a finding of MI. [[H&E stain]].
| Synonyms  =
| Micro      = wavy fibers, myocyte [[necrosis]] with loss of cross striations, [[contraction band necrosis|contraction bands]], edema, hemorrhage, neutrophilic infiltrate, pyknosis of nuclei, loss of nuclei (karyolysis), loss of striations, macrophage and mononuclear infiltration, fibrovascular response, fibrovascular response, [[granulation tissue]], myocardial fibrosis (old)
| Subtypes  =
| LMDDx      = [[cardiac amyloidosis]] for old infarct, [[myocarditis]]
| Stains    =
| IHC        =
| EM        =
| Molecular  =
| IF        =
| Gross      = myocardial pallor, hyperemia (redness), yellow lesion with hyperemic border, white (fibrosis)
| Grossing  =
| Site      = [[heart]]
| Assdx      = [[coronary artery atherosclerosis]]+/-plaque rupture, +/-thrombosis, cocaine use
| Syndromes  =
| Clinicalhx =
| Signs      = abnormal EKG - esp. ST elevation
| Symptoms  = classic findings: retrosternal chest pain +/- with radiation down the arms, nausea & vomiting, diaphoresis
| Prevalence =
| Bloodwork  = elevated troponin, CK-MB
| Rads      =
| Endoscopy  =
| Prognosis  = dependent on extent
| Other      =
| ClinDDx    = varies by presentation - usu. [[aortic dissection]], [[acute pneumonia]], [[pulmonary embolism]], GI pathology, 
| Tx        =
}}
'''Myocardial infarction''', abbreviated '''MI''', is death of cardiac muscle due to a compromised blood supply. In the context of pathology, they are occasionally seen at [[autopsy]].
 
==General==
===Clinical===
*Usually diagnosed clinically - with blood work (troponin, CK-MB) or EKG.
*MI may be precipitated by cocaine use... and further exacerbated by treatment with a beta-blocker.<ref name=pmid19127137>{{cite journal |author=Mohamad T, Kondur A, Vaitkevicius P, Bachour K, Thatai D, Afonso L |title=Cocaine-induced chest pain and beta-blockade: an inner city experience |journal=Am J Ther |volume=15 |issue=6 |pages=531-5 |year=2008 |pmid=19127137 |doi=10.1097/MJT.0b013e3181758cfc |url=}}</ref>
*Acute myocardial infarction (abbreviated AMI) = MI < 6 hours old.<ref name=pmid19258462>{{Cite journal  | last1 = Senter | first1 = S. | last2 = Francis | first2 = GS. | title = A new, precise definition of acute myocardial infarction. | journal = Cleve Clin J Med | volume = 76 | issue = 3 | pages = 159-66 | month = Mar | year = 2009 | doi = 10.3949/ccjm.75a.08092 | PMID = 19258462 | URL = http://www.ccjm.org/content/76/3/159.full }}</ref>
**Usually no [[PMN]] infiltrate.
 
Classic symptoms:
*Retrosternal chest pain +/- with radiation down the arms.
*Nausea & vomiting.
*Diaphoresis.
 
Enzymatic tests:<ref>URL: [http://pro2services.com/Lectures/Fall/CardEnz/a6mienz.gif http://pro2services.com/Lectures/Fall/CardEnz/a6mienz.gif]. Accessed on: 27 April 2012.</ref>
*CK: peaks at day 1, resolves after 2-3 days.
*AST: peaks close to day 2, resolves after 4-5 days.
*LDH: peaks day 2, resolves after ~6 days.
 
===Complications===
Complications of MI:<ref name=Ref_PCPBoD8_293>{{Ref PCPBoD8|293}}</ref>
*Contractile dysfunction.
*[[Cardiac arrhythmia]].
*Aneurysm formation, e.g. left ventricular aneurysm.
*Ventricular rupture:
**Ventricular free wall rupture.
**Ventricular septal rupture.
*[[Fibrinous pericarditis]].
**''Dressler's syndrome'' [[AKA]] ''postmyocardial infarction syndrome''<ref name=pmid5039567>{{cite journal |author=Hutchcroft BJ |title=Dressler's syndrome |journal=Br Med J |volume=3 |issue=5817 |pages=49 |year=1972 |month=July |pmid=5039567 |pmc=1788531 |doi= |url=}}</ref>; pericarditis post-myocardial infarction +/- pericardial effusion (clinically tamponade).
*Mural thrombosis.
*Extension of MI.
 
==Gross==
Sequence:<ref>[http://library.med.utah.edu/WebPath/TUTORIAL/MYOCARD/MYOCARD.html http://library.med.utah.edu/WebPath/TUTORIAL/MYOCARD/MYOCARD.html]</ref>
*18-24 hours - myocardial pallor.
*1-3 days - pallor, moderate hyperemia (redness due to congestion with blood).
*3-7 days - yellow lesion with hyperemic border.
*10-21 days - maximally yellow.
*6 weeks - white (fibrosis).
 
==Microscopic==
Sequence:<ref>[http://library.med.utah.edu/WebPath/TUTORIAL/MYOCARD/MYOCARD.html http://library.med.utah.edu/WebPath/TUTORIAL/MYOCARD/MYOCARD.html]</ref>
*1-3 hours - Wavy (myocardial) fibers
*4-12 hours - Coagulative [[necrosis]] & loss of cross striations, [[contraction band necrosis|contraction bands]], edema, hemorrhage, PMN infiltrate.
*18-24 hours - Coagulative necrosis, pyknosis of nuclei, and marginal contraction bands.
*1-3 days - Loss of nuclei (karyolysis), loss of striations, abundant PMNs.
*3-7 days - Macrophage and mononuclear infiltration, fibrovascular response.
*10-21 days - Fibrovascular response, prominent granulation tissue.
*6 weeks - Fibrosis.
 
Images:
*[http://path.upmc.edu/cases/case158/micro.html MI (upmc.edu)].
 
===Contraction band necrosis===
General:
*Mediated by catecholamines.<ref>{{cite journal |author=Hopster DJ, Milroy CM, Burns J, Roberts NB |title=Necropsy study of the association between sudden cardiac death, cardiac isoenzymes and contraction band necrosis |journal=J. Clin. Pathol. |volume=49 |issue=5 |pages=403–6 |year=1996 |month=May |pmid=8707956 |pmc=500481 |doi= |url=}}</ref>
*Thought to arise in reperfusion from hypercontraction.
 
Microscopic:
*Thick intensely eosinophilic staining bands (on H&E) ~ typically 4-5 micrometres wide
**Span the short axis of myocyte.
**Can be thought of bunched-up striae.
 
Notes:
*Better seen with special stains (Masson or Gomori trichrome).<ref>{{cite journal |author=Hopster DJ, Milroy CM, Burns J, Roberts NB |title=Necropsy study of the association between sudden cardiac death, cardiac isoenzymes and contraction band necrosis |journal=J. Clin. Pathol. |volume=49 |issue=5 |pages=403–6 |year=1996 |month=May |pmid=8707956 |pmc=500481 |doi= |url=}}</ref>
 
====Images====
<gallery>
Image:MI_with_contraction_bands_high_mag.jpg | CBN - high mag. (WC)
Image:MI_with_contraction_bands_very_high_mag.jpg | CBN - very high mag. (WC)
</gallery>
 
==See also==
*[[Heart]].
 
==References==
{{Reflist|2}}


[[Category:Diagnosis]]
[[Category:Diagnosis]]
[[Category:Heart]]

Revision as of 02:12, 8 January 2014

Myocardial infarction
Diagnosis in short

Contraction band necrosis - a finding of MI. H&E stain.
LM wavy fibers, myocyte necrosis with loss of cross striations, contraction bands, edema, hemorrhage, neutrophilic infiltrate, pyknosis of nuclei, loss of nuclei (karyolysis), loss of striations, macrophage and mononuclear infiltration, fibrovascular response, fibrovascular response, granulation tissue, myocardial fibrosis (old)
LM DDx cardiac amyloidosis for old infarct, myocarditis
Gross myocardial pallor, hyperemia (redness), yellow lesion with hyperemic border, white (fibrosis)
Site heart
Associated Dx coronary artery atherosclerosis+/-plaque rupture, +/-thrombosis, cocaine use
Signs abnormal EKG - esp. ST elevation
Symptoms classic findings: retrosternal chest pain +/- with radiation down the arms, nausea & vomiting, diaphoresis
Blood work elevated troponin, CK-MB
Prognosis dependent on extent
Clin. DDx varies by presentation - usu. aortic dissection, acute pneumonia, pulmonary embolism, GI pathology,

Myocardial infarction, abbreviated MI, is death of cardiac muscle due to a compromised blood supply. In the context of pathology, they are occasionally seen at autopsy.

General

Clinical

  • Usually diagnosed clinically - with blood work (troponin, CK-MB) or EKG.
  • MI may be precipitated by cocaine use... and further exacerbated by treatment with a beta-blocker.[1]
  • Acute myocardial infarction (abbreviated AMI) = MI < 6 hours old.[2]
    • Usually no PMN infiltrate.

Classic symptoms:

  • Retrosternal chest pain +/- with radiation down the arms.
  • Nausea & vomiting.
  • Diaphoresis.

Enzymatic tests:[3]

  • CK: peaks at day 1, resolves after 2-3 days.
  • AST: peaks close to day 2, resolves after 4-5 days.
  • LDH: peaks day 2, resolves after ~6 days.

Complications

Complications of MI:[4]

  • Contractile dysfunction.
  • Cardiac arrhythmia.
  • Aneurysm formation, e.g. left ventricular aneurysm.
  • Ventricular rupture:
    • Ventricular free wall rupture.
    • Ventricular septal rupture.
  • Fibrinous pericarditis.
    • Dressler's syndrome AKA postmyocardial infarction syndrome[5]; pericarditis post-myocardial infarction +/- pericardial effusion (clinically tamponade).
  • Mural thrombosis.
  • Extension of MI.

Gross

Sequence:[6]

  • 18-24 hours - myocardial pallor.
  • 1-3 days - pallor, moderate hyperemia (redness due to congestion with blood).
  • 3-7 days - yellow lesion with hyperemic border.
  • 10-21 days - maximally yellow.
  • 6 weeks - white (fibrosis).

Microscopic

Sequence:[7]

  • 1-3 hours - Wavy (myocardial) fibers
  • 4-12 hours - Coagulative necrosis & loss of cross striations, contraction bands, edema, hemorrhage, PMN infiltrate.
  • 18-24 hours - Coagulative necrosis, pyknosis of nuclei, and marginal contraction bands.
  • 1-3 days - Loss of nuclei (karyolysis), loss of striations, abundant PMNs.
  • 3-7 days - Macrophage and mononuclear infiltration, fibrovascular response.
  • 10-21 days - Fibrovascular response, prominent granulation tissue.
  • 6 weeks - Fibrosis.

Images:

Contraction band necrosis

General:

  • Mediated by catecholamines.[8]
  • Thought to arise in reperfusion from hypercontraction.

Microscopic:

  • Thick intensely eosinophilic staining bands (on H&E) ~ typically 4-5 micrometres wide
    • Span the short axis of myocyte.
    • Can be thought of bunched-up striae.

Notes:

  • Better seen with special stains (Masson or Gomori trichrome).[9]

Images

  • CBN - high mag. (WC)

  • CBN - very high mag. (WC)

See also

References

  1. ↑ Mohamad T, Kondur A, Vaitkevicius P, Bachour K, Thatai D, Afonso L (2008). "Cocaine-induced chest pain and beta-blockade: an inner city experience". Am J Ther 15 (6): 531-5. doi:10.1097/MJT.0b013e3181758cfc. PMID 19127137.
  2. ↑ Senter, S.; Francis, GS. (Mar 2009). "A new, precise definition of acute myocardial infarction.". Cleve Clin J Med 76 (3): 159-66. doi:10.3949/ccjm.75a.08092. PMID 19258462.
  3. ↑ URL: http://pro2services.com/Lectures/Fall/CardEnz/a6mienz.gif. Accessed on: 27 April 2012.
  4. ↑ Mitchell, Richard; Kumar, Vinay; Fausto, Nelson; Abbas, Abul K.; Aster, Jon (2011). Pocket Companion to Robbins & Cotran Pathologic Basis of Disease (8th ed.). Elsevier Saunders. pp. 293. ISBN 978-1416054542.
  5. ↑ Hutchcroft BJ (July 1972). "Dressler's syndrome". Br Med J 3 (5817): 49. PMC 1788531. PMID 5039567. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1788531/.
  6. ↑ http://library.med.utah.edu/WebPath/TUTORIAL/MYOCARD/MYOCARD.html
  7. ↑ http://library.med.utah.edu/WebPath/TUTORIAL/MYOCARD/MYOCARD.html
  8. ↑ Hopster DJ, Milroy CM, Burns J, Roberts NB (May 1996). "Necropsy study of the association between sudden cardiac death, cardiac isoenzymes and contraction band necrosis". J. Clin. Pathol. 49 (5): 403–6. PMC 500481. PMID 8707956. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC500481/.
  9. ↑ Hopster DJ, Milroy CM, Burns J, Roberts NB (May 1996). "Necropsy study of the association between sudden cardiac death, cardiac isoenzymes and contraction band necrosis". J. Clin. Pathol. 49 (5): 403–6. PMC 500481. PMID 8707956. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC500481/.
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