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Diagnostics > Cardiac enzymes > Flashcards

Cardiac enzymes Flashcards

1
Q

MI

A
  • Temporary diminished supply of blood to myocardium –> reversible effects
  • 1 cause of chest pain
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2
Q

MI cause

A

Obstruction or constriction of coronary vessels

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3
Q

Myocardial ischemia

A

May develop:

  1. Slowly as aa become obstructed over time
  2. Quickly when artery becomes suddenly obstructed
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4
Q

Myocardial ischemia causes

A
  • Coronary artery disease = most common
  • Blood clot
  • Coronary artery spasm
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5
Q

CAD

A
  • Plaques comprised of cholesterol which builds up in arterial wall
  • Blood flow restricted &/or rupture of plaques –> blood clot
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6
Q

Blood clot

A
  • Plaque builds up, ruptures –> localized clot

- May travel to coronary aa from another area of body (rare)

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7
Q

Coronary artery spasm

A

Arterial wall spasm –> temporary interruption of blood flow

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8
Q

MI sx

A
  • Chest pain
  • Dyspnea
  • Nausea
  • Pain radiating to neck, arms, back
  • Epigastric pain
  • Fatigue/ weakness
  • Dizziness
  • Impeding sense of doom
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9
Q

What type of patients present atypically w/ an MI?

A
  • Elderly
  • Females
  • Diabetics
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10
Q

Acute MI

A

Myocardial cell death due to prolonged ischemia

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11
Q

Tall T waves

A
  • Earliest change seen in acute MI

- Most often seen in anterior chest leads

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12
Q

Flattened T waves

A

Often seen in pts w/ myocardial ischemia, but often non-specific

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13
Q

Q waves

A

Typically seen in left-sided leads

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14
Q

Pathological Q waves

A
  • > 40 ms wide
  • > 2 mm
  • 25% of depth of QRS
  • Seen in leads V1-3
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15
Q

Pathological Q wave differential

A
  • MI
  • Cardiomyopathies
  • Rotation of heart
  • Lead placement errors
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16
Q

Intracellular enzymes & proteins

A
  • Creatine kinase (CK or total CK)
  • Creatine kinase myoglobin (CK-MB)
  • Myoglobin (MB)
  • Troponin **
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17
Q

CK

A

Released w/ brain or muscle injury

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18
Q

What are the 3 isoenzymes of CK?

A

Total CK:

  • CK-MB in heart
  • CK-MM in muscle
  • CK-BB in brain
19
Q

CK-MB may also present where?

A
  • Small intestine
  • Tongue
  • Diaphragm
  • Uterus
  • Prostate
20
Q

When does CK-MB increase?

A

4-6 hrs after myocardial injury

21
Q

When does CK-MB peak?

A

18-24 hrs

22
Q

When does CK-MB normalize?

A

48-72 hrs

23
Q

What is the normal range of CK-MB?

A

5-25

24
Q

When is CK-MB most sensitive/specific to MI?

A

Within 24-36 hrs of onset of chest pain

25
Q

MB

A
  • Protein found in skeletal & cardiac muscle
  • Lower sensitivity
  • Considered unnecessary w/ troponin testing
26
Q

When does MB increase?

A

2-4 hrs after myocardial injury

27
Q

When does MB peak?

A

6-12 hrs

28
Q

When does MB normalize

A

24-36 hrs

29
Q

What is the normal range for MB?

A

0-85

30
Q

Troponin categories

A
  • Troponin I (TnI)
  • Troponin T (TnT)
  • Troponin C (TnC)
  • All regulatory proteins part of skeletal & cardiac muscle
  • Each has unique fxn
31
Q

Which troponin inhibits the interaction of myosin w/ actin?

A

Troponin I

32
Q

Which troponin binds troponin components to tropomyosin?

A

Troponin T

33
Q

Which troponin contains the binding sites for Ca2+?

A

Troponin C

- Initiates contraction

34
Q

Which troponins are immunologically distinct enzymes?

A

I & C

35
Q

Which troponin has the greatest sensitivity for MI?

A

Troponin I

  • Detects small infarcts, myocardial injury
  • May be elevated for other reasons other than MI
36
Q

When does troponin I increase?

A

4-8 hrs

37
Q

When does troponin I peak?

A

18-24 hrs

38
Q

When does troponin I normalize?

A

5-14 days

39
Q

What is normal troponin I?

A

<0.1

40
Q

What range of troponin I is considered indeterminate?

A

.1-.9

41
Q

What range of troponin I is myocardial injury likely?

A

1.0-1.4

42
Q

W/ troponin I, what level is definitive for myocardial injury?

A

> or = to 1.5

43
Q

Which cardiac enzymes are more accurate & sensitive? Serial markers or single initial?

A

Serial markers

  • 4 to 6 hr intervals X 3
  • Utilized less in unstable angina

Diagnostics (11 decks)

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