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Common Congenital Heart Lesions - page 43 / 126

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Serum Biomarkers

Myocardial necrosisÆdefective cell membranesÆrelease of serum biomarkers

  • Detection of serum biomarkers serve important diagnostic & prognostic roles

  • These are higher than normal in ACS & are released in a specific temporal

sequence (Myogloblin then CK-MB & Troponins)

Myoglobin

  • Cytosolic, O2 binding protein of the cardiac & skeletal muscle

  • Earliest marker detected (released 2-4 hours after injury)

  • Rapidly cleared via the kidneys

  • Highly sensitive, but NOT specific since found in cardiac & skeletal muscle

  • Of limited diagnostic value

  • Improved specificity if combined with Carbonic Anhydrase III

tests…however this is very expensive

CK-MB

  • CK isoenzyme found mainly in the heart (although found in other places too, including the skeletal muscle, uterus, prostate, gut, etc.)

  • Released 3-12 hours after injury

  • Has a delayed peaking pattern distinct from other tissues with CK-MB

  • Has a sensitivity & specificity similar to Tn (this is increased even more is tested together)

  • To distinguish CK-MB released from the heart vs. skeletal muscle, determine the relative index…usually >2.5-5% if there’s myocardial injury

Relative Index= CK-MB/total CK

Troponins (TnT & TnI)

  • Unique TnT & TnI found in the heart vs. skeletal muscle b/c of regulation by different genesÆslight, AA variations…Thus, these are considered to be the Gold Standard of biomarkers

  • Absent in healthy patients

  • Released 3-6 hours after injury (so typically see rising CK-MB & Tn levels)

  • Have stability issues…you must get the sample to the lab ASAP!

LDH

  • Nonspecific marker

  • Peaks 3-5 days after MI

  • Great specificity when tested with CK-MB

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