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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

Pathological Q Waves

>1 mm wide
>2 mm deep
Seen in leads V1-V3