Flashcards in Cardiac Enzymes-Diagnostics Deck (28)
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1
Ischemia
-Temporary diminished supply of blood (oxygen and nutrients) to the myocardium resulting in reversible effects
-Due to obstruction or constriction of the coronary vessels supplying the myocardium
2
Myocardial Ischemia
-Ischemia may develop slowly as arteries become obstructed over time or it can occur quickly when an artery becomes suddenly obstructive
3
Causes of an MI
-Coronary artery disease
-Blood clot
-Coronary artery spasm
4
CAD
-Most common cause of ischemia
-Plaques comprised mostly of cholesterol which build up in arterial wall
-Blood flow restricted by build up of plaques and/or rupture of plaques which can result in blood clot
5
Blood clot
-Plaque build up ruptures which results information of localized clot
-Blood clot may travel to the coronary arteries from another area of the body= rare
6
Coronary artery spasm
-Arterial wall spam resulting in in temporary interruption of blood flow
7
Acute MI
-Myocardial cell death due to prolonged ischemia
8
Histological cell death
-Takes about 20 minutes
9
Complete necrosis of myocardial cells
=2-4 hrs
10
ST depression greater than or equal to 1 mm
-More specific and coveys worse prognosis
11
ST depression greater than or equal to 2 mm in greater than or equal to 3 leads
-Associated with a high probability of NSTEMI and predicts significant mortality
-->35% mortality @ 30 days
12
ST elevation
-ST elevation @ the J point in 2 contiguous leads or more of 0.2 mV or more in males or 0.15 mV ore more in females in leads V2-V3
13
Tall T waves
-earliest changes seen in acute MI
-Most often seen in the anterior chest leads
14
Isolated tall T waves
-In leads V1-V3 may be due to ischemia of posterior wall of the left ventricle
-->the mirror image of T wave inversion
15
Creatine Kinase
-An enzyme released with muscle or brain tissue injury
16
Total CK
Ck-MB in heart
CK-MM in muscle
CK-BB in brain
17
CK-MB
-Begins to increase 4-6 hrs after myocardial injury
-Peaks in 18-24 hrs
-Normalizes in 48-71 hrs
18
Troponin I
Inhibits the interaction of myosin with actin
19
Troponin T
Binds the troponin components to Tropomyosin
20
Troponin C
Contains the binding sites for the Ca2+ that helps initiate contraction
21
Troponin-I
-Greatest sensitivity for myocardial injury
22
Troponin-I onset
-Begin to increase 4-8 hrs after an MI
23
Troponin-I Peak
@ 18-24 hrs
24
How long does a Troponin-I stay elevated?
5-14 days
25
Myoglobin (MB)
Protein found in skeletal and cardiac muscle
26
When does MB increase?
2-4 hrs after myocardial injury
=Peaks the earliest!
-->diminished utility due to lower sensitivity
27
When is the CK-MB the most sensitive and specific for myocardial injury?
when measured w/in 24-36 hrs of the onset of chest pain
28
