Lipp Vis Nursing ChaptLWBK1630_C02_p013-068

Chapter 2 • Cardiovascular Care  17

Understanding Clotting

Clotting is initiated through two different pathways.

PICTURING PATHO

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

Factor XII

XIIa

Tissue thromboplastin

Factor XI XIa

Factor IX IXa

Factor VII VIIa

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

Factor VIII VIIIa

Factor X Xa

Factor V

Platelet phospholipid

Prothrombin Thrombin

Fibrinogen Fibrin

Factor XIII

S t a b i l i z e d f i b r i n c l o t