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Flashcards in Cardiac Lab Evaluation Deck (16)
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1

What are cardiac biomarkers used for?
When are they released?
what are 3 examples?

-the dx and risk stratification of patients with cardiac sx

**not necessary for the dx of pts who present with ischemic chest pain and EKGs with ST elevation

-proteins that leak from the myocardium secondary to ischemia

Examples: Troponin, Creatinine Kinase, Myoglobin

2

Troponin
what is it
what types are isolated for cardiac muscle
when is it released
what does it identify

what is it
-protein that is integral to muscle contraction

what types are isolated for cardiac muscle
-Troponin I and Troponin T

when is it released
-released into systemic circulation when there is myocyte necrosis that leads to cell membrane disruption

what does it ID
-patients at increased risk for adverse cardiac events (the degree of troponin is correlated with the extent of myocardial injury)

3

Troponin
when do levels peak
what drug could cause a significant rise

when do levels peak
-rise within 2-3 hours and peak at 12-16 hours

what drug could cause a significant rise
-thrombolytics due to "wash out"

4

Cardiac causes of elevated plasma cardiac troponin other than ACS

-cardiac contusion
-cardiac surgery
-cardioversion
-CHF
-aortic dissection
-pericarditis

5

Non-Cardiac causes of elevated plasma cardiac troponin other than ACS

-PE
-Severe pulmonary HTN
-Renal failure
-stroke
-sepsis

6

How to measure troponin

-measure at presentation to the ED via blood
-repeat every 3-6 hours
-normals vary from lab to lab, so use their reference range

*pts with impaired renal function may have falsely elevated levels

***other cardiac biomarkers are not as sensitive or specific, so use troponin

7

Creatine Kinase
what does an elevated level suggest?
what disease may increase levels?

what does an elevated level suggest?
-muscle damage and can be indicative of injury, rhabdomyolysis, MI, myositis, myocarditis

what disease may increase levels?
-hypothyroidism

8

What are the three types (isoenzymes) of Creatine Kinase?

CK-MM- skeletal muscle and heart
CK-MB- heart
CK-BB- brain

9

CK-MB
where is it mostly found?
when can it be detected and when does it peak?
prognostic value?
what does CK-MB/CK relative help determine?

where is it mostly found?
-concentrated in the myocardium

when can it be detected and when does it peak?
-noted at 4-6 hours after onset of sx and peaks at 24 hours

prognostic value
-limited in pts with ACS

what does CK-MB/CK relative help determine?
-cardiac vs. skeletal muscle injury
-ratio less than 3=skeletal muscle
-rato greater than 5= cardiac muscle

10

Myoglobin
where is it found
when does it peak
high or low sensitivity for AMI

where is it found
-in skeletal and cardiac muscle

when does it peak
-6-12 hours

high or low sensitivity for AMI?
-low sensitivity due to lack of cardioselectivity

11

What are some lab tests for CV risk assessment?

lipid profile
hs-CRP
Homocystine

12

How is a high sensitivity CRP different from a CRP?

CRP measures general inflammation

hs-CRP
- elevated means 2-3 times the risk of MO, stroke, sudden cardiac death, and peripheral arterial disease
-stronger predictor of heart disease and stroke than LDL
-major use is in primary prevention**

13

How to lower hs-CRP

-cardiac diet
-exercise
-BP control
-smoking cessation
-statins

14

Homocystine
what is it
elevated levels related to...

what is it
-amino acid

elevated levels related to...
-genetics and low levels of B6, B12, and folate
--hyperhomocystinemia can lead to blood clots, heart attacks, stroke, miscarriage, pre-eclampsia

15

Brain naturetic peptide (BNP)
produced where
stimulates release of what
help in differentiating between...

produced where
-ventricles and atria in response to an increase in volume and pressure

stimulates release of what
-ANP (body rids itself of sodium in an attempt to decrease total body water volume)

help in differentiating between...
-CHF and lung disease
--if a pt has SOB and COPD and the BNP is fine its probably due to COPD. If BNP is high it might be the heart

16

causes of elevated BNP other than CHF

-elderly
-women
-renal failure
-cirrhosis
-acute coronary syndrome
-myocarditis
-PE
-primary pulmonary HTN