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Chapter 2
•
Cardiovascular Care
17
PICTURING
PATHO
Tests to Identify Myocardial
Infarction
After myocardial infarction (MI),
myocardial cell death can be
recognized by the appearance, in
the blood, of different proteins
released into the circulation from
the damaged myocytes: myoglobin,
cardiac troponin T and I, CK, and
LDH.
Myoglobin
•
Elevated
•
First marker of cardiac injury after
acute MI
CK-MB
•
Returns to normal quickly
•
Most reliable when reported as a
percentage of total creatine kinase
(CK) (relative index)
Troponin I
•
Isotypes of troponin found only in
myocardium
•
Elevated
•
Specific to myocardial damage
Troponin T
•
Isotype of troponin that is less
specific to myocardial damage
(can indicate renal failure)
•
Elevated
•
Determined quickly at bedside
S t a b i l i z e d
f i b r i n
c l o t
Factor XII
XIIa
Factor XI XIa
Factor IX IXa
Factor VIII VIIIa
Factor VII VIIa
Factor X Xa
Factor V
Platelet phospholipid
Prothrombin Thrombin
Fibrinogen Fibrin
Factor XIII
I n t r i n s i c p a t hwa y
Activated by contact with
damaged vessel surface
E x t r i n s i c p a t hwa y
Activated by
damaged tissue
Tissue
thromboplastin
Understanding Clotting
Clotting is initiated through two different pathways.