Cardiac Laboratory Evaluation Flashcards
What are the cardiac biomarkers? 3
Lab tests for CV risk assessment?
Whats the lab test for heart failure management? 1
- Troponin
- CK-MB
- Myoglobin
- hs-CRP
- homocystine
- BNP
Cardiac biomarkers
Used for what?
What are they not necessary for? 2
Used in the diagnosis and risk stratification of patients with cardiac symptoms.
Not necessary for the diagnosis of patients who present with
1. ischemic chest pain and
2. EKGs with ST elevation.
They got there early enough so the lab tests wont be elevated yet
Follow the trend to peak
What are cardiac biomarkers useful in assessing and why?
- Useful to assess for myocardial injury
2. Proteins that leak from the myocardium secondary to ischemia
What are the differences between the different biomarkers?
2
- Time from ischemic injury to elevation of the lab values
2. Variable degrees of specificity for myocardial injury
Troponin is a highly specific marker for what?
cardiac muscle cell death.
- What is troponin integral to in normal functioning?
- Found in what kind of muscle? 2
- What are Trop I and T specific for?
- Released into the systemic circulation when there is what?
- Protein that is integral to muscle contraction
- Found in skeletal and cardiac muscle
- Troponin I and Troponin T are isolated proteins specific for cardiac muscle
- myocyte necrosis that leads to cell membrane disruption
Troponin can identify patients at increased risk for?
How does the level of troponin affect the outcome?
adverse cardiac events
The higher the troponin the worse the outcome
The degree of troponin rise correlates with the extent of what?
myocardial injury
Troponin rises within 1.____ hours after cardiac insult and may stay elevated for 2.___ _____ to 3.__ ____ after event
Peak at 4._____ hours
“Wash out” after 5.__________ will cause significant rise in Troponins
- 2-3
- 10 days
- 2 weeks
- 12-16
- thrombolytics
Cardiac causes of elevated plasma cardiac troponin other than ACS
16
- Cardiac contusion
- Cardiac surgery
- Cardioversion
- Endomyocardial biopsy
- CHF
- Aortic dissection
- Post PCI
- Rhabdomyolysis
- Myocarditis
- Aortic valve disease
- Hypertrophic cardiomyopathy
- Tachyarrhythmia
- Bradyarrhythmia, heart block
- Apical ballooning syndrome
- Pericarditis
- Endocarditis
Noncardiac causes of elevated plasma troponin
12
- Pulmonary embolism
- Severe pulmonary hypertension
- Renal failure**
- Stroke
- Subarachnoid hemorrhage
- Infiltrative disease, e.g.
- Amyloidosis
- Cardiotoxic drugs
- Sepsis
- Critical illness
- Extensive burns
- Extreme exertion
How troponin is used to diagnose MI. When should we get it?
3
- Measure at presentation to the ED
- Repeat in 3-6 hours post symptom onset
- May repeat beyond 6 hours if risk factors are present
What are the factors that would make us want to check a troponin after 6 hours?
3
- Initial troponin is normal
- EKG changes are present
- Patient has many high risk features
If we dont have perfusion what happens to our troponin level over time?
Still not getting perfusion to the area so there is continuing necrosis and troponin levels stay higher longer (still peak though)
The highly sensitive assays have a high negative predictive value for ______ in the setting of chest pain 2 hours post onset of symptoms
Pts with impaired ______ function may have falsely elevated levels of troponin
NSTEMI (not an MI but they still might have unstable angina)
renal!!!!!!!!
For the diagnosis of MI what biomarkers should we use?
Use Troponin
The other cardiac biomarkers are not as sensitive or specific
Where is creatine kinase found?
What do elevated levels suggest? 6
It may increase in what syndrome (and why?)
Enzyme found in muscle cells
Elevations suggest muscle damage and can be indicative of 1. injury,
- rhabdomyolysis,
- MI,
- myositis,
- myocarditis
- Elevated in 1% of patients on statins
May increase in hypothyroidism
When T3 is low, CK becomes elevated
Creatine Kinase has 3 isoenzymes. What are they?
CK-MM (skeletal muscle and heart)
CK-MB (Heart)
CK-BB (Brain)
Describe when each of the following are elevated:
CK-MM? 2
CK-MB? 3
CK-BB? 6
CK-MM (skeletal muscle and heart)
Elevated in muscle damage to
1. heart or
2. skeletal muscle, crush injury, seizures, etc.
CK-MB (Heart) Elevated in 1. MI, 2. inflammation of heart muscle, 3. RV and LV strain
CK-BB (Brain) Elevated in 1. brain injury, 2. meningitis, 3. severe shock, 4. stroke, 5. hypothermia, 6. restricted blood flow to the bowel
- CK-MB is concentrated where?
- Also found where to a lesser degree?
- When is it elevated after onset of symtpoms?
- Peaks when?
- Normalizes when?
- in the myocardium
- Also found in skeletal muscle to a lesser degree
- Noted at 4-6 hours after onset of symptoms
- Peaks at 24 hours
- Normalizes in 48-72 hours
- Isolated CK-MB elevation has limited prognostic value in patients with what?
- What is the CRUSADE Registry?
- GRACE registry (in hospital mortality)?
- ACS
- Patients with negative troponin but CK-MB positive their mortality = to patients who had negative troponin and CK-MB
- Both troponin and CK-MB positive = highest
Troponin positive and CK-MB negative = intermediate
Both markers negative = lowest
CK-MB/CK relative index helps to determine what?
How is this calculated?
cardiac vs. skeletal muscle injury.
Calculated by the ratio of CK-MB to the total CK
CK-MB/CK relative index is at what value if its skeletal muscle?
Cardiac?
Ratio less than 3 = skeletal muscle source
Ratio greater then 5 = cardiac source
- What is myoglobin?
- Rises when after onset of infarction?
- Peaks when?
- Normalizes when?
- Low sensitivity why?
- Myoglobin is a protein found in skeletal and cardiac muscle
- Typically rises 2-4 hours after onset of infarction
- Peaks at 6-12 hours
- Normalizes in 24-36 hours
- Low sensitivity for AMI due to lack of cardioselectivity
Lab tests for CV risk assessment
- Lipid profile
(already covered in endocrine) - hs-CRP
- Homocystine
For ruling out/in acute myocardial infarction vs. unstable angina
What is the go to test?
Troponin is the go to test
Remember with symptoms or an abnormal EKG a person may be having an MI with an________troponin if the lab is drawn prior to __ hours of onset of symptoms…don’t treat the labs treat your patient
negative
2
What does CRP measure?
When is it elevated?
CRP measures general levels of inflammation in the body
Elevated in infections, chronic disease, surgery
Elevated hs-CRP causes a 2-3 times the risk of what disease processes?
4
Its a stronger predictor of what two things than LDL?
Major use is what?
In secondary prevention it might predict what?
- MI,
- stroke,
- sudden cardiac death and
- peripheral arterial disease
Stronger predictor of
- heart disease and
- stroke than LDL
Major use is in primary prevention
In secondary prevention may predict recurrent coronary events
To lower hs-CRP what should we tell our pts to do?
5
- Cardiac diet
- Exercise
- BP control
- Smoking cessation
- Statins
- What is Homocystine?
- What is it acquired from?
- What are elevated levels of homocystine related to? 2
- Amino acid
- Acquired mostly from meat protein
- Elevated levels of homocystine are related to
- -genetics and
- -low levels of B6, B12 and folate
Elevated levels of homocystine have been linked to____?
Hyperhomocystinemia may cause?
6
CVD
- Prone to endothelial injury
- Blood clots
- Heart attack
- Stroke
- Miscarriage
- Pre-eclampsia
BNP – Brain naturetic peptide
is produced by what?
In response to what?
ventricles and atria in response to an increase in volume and pressure
(generally a measure of how much volume is in the body-this is too much stretching if too much volume)
BNP stimulates the release of what?
How?
Stimulates the release of atrial naturetic peptide
Body rids itself of sodium in an attempt to decrease total body water volume
What may BNP be helpful in differentiating?
between CHF and lung disease
Do not use routinely to follow stable CHF
Causes of elevated BNP other than CHF
8
- Elderly
- Women
- Renal failure
- Cirrhosis
- Acute coronary syndrome
- Myocarditis
- Pulmonary embolism
- Primary pulmonary hypertension
