Cardiac Lab Evaluation Flashcards
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
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)
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”
Cardiac causes of elevated plasma cardiac troponin other than ACS
- cardiac contusion
- cardiac surgery
- cardioversion
- CHF
- aortic dissection
- pericarditis
Non-Cardiac causes of elevated plasma cardiac troponin other than ACS
- PE
- Severe pulmonary HTN
- Renal failure
- stroke
- sepsis
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
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
What are the three types (isoenzymes) of Creatine Kinase?
CK-MM- skeletal muscle and heart
CK-MB- heart
CK-BB- brain
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
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
What are some lab tests for CV risk assessment?
lipid profile
hs-CRP
Homocystine
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**
How to lower hs-CRP
- cardiac diet
- exercise
- BP control
- smoking cessation
- statins
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
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
