Cardiac labs

Question 1

Acute Coronary Syndrome (ACS)

Answer 1

• when stable angina become more aggressive
  
  • unstable angina
  • NSTEMI
  • STEMI

Question 2

biomarkers in ACS

Answer 2

• troponin (Tn)
  
  • Most widely used and helpful cardiac biomarker
• creatine kinase- muscle band (CK-MB)
  
  • A second biomarker is creatine kinase (CK), particularly its myocardial-specific isoenzyme

Question 3

dx of AMI

Answer 3

• AMI are characterized by a rise and fall in biomarkers of myocyte injury and imply the death of cardiac myocytes caused by ischemia
• must also have one of these
  
  • ischemic symptoms
  • ECG changes suggestive of ischemia
  • imaging evidence of new loss of viable myocardium
• w/out elevation of biomarkers only Unstable Angina

Question 4

Dx for range from AMI to MI

Answer 4

Question 5

More DX of ACS

Answer 5

Question 6

Troponin Indication

Answer 6

• In the ER, patients with suspected ACS should have a troponin level drawn at presentation and again at 3 and 6 hours after symptom onset
• Drawing a troponin level may also be useful in the setting of delayed presentation, as remain elevated for 7-10 -14 days after infarct

Question 7

Troponin Means..

Answer 7

• ¨Elevated troponin not seen exclusively in AMI; ↑ levels (usually more modest and stable elevations) also may be seen in following diagnoses:
  
  • Inflammatory cardiac diseases (myocarditis, endocarditis, pericarditis)
  • Severe pulmonary hypertension, including PE
  • Severe HF
• Troponin release can also be induced by cardiac trauma, as occurs during CPR, electrical cardioversion, or implantable cardioverter defibrillator (ICD) firings
• Mild stable elevation also seen in severe renal disease

Question 8

CK-MB

Answer 8

• Normal range: 0-3 ng/ml
• CK-MB typically becomes elevated around 4 hours after the onset of infarction, peaks at 12 to 24 hours, and returns to baseline within 36 to 48 hours

Question 9

comparison of cardiac biomarkers

Answer 9

Question 10

Brain Natriuretic Peptide (BNP)

Answer 10

• BNP is a hormone released primarily from the heart, particularly the ventricular myocytes
• Released in response to ↑ ventricular wall tension – “volume or pressure overload”
• Measuring BNP is an add to the diagnosis of heart failure
• Normal range of BNP: < 100 pg/mL

Question 11

Brain Natriuretic Peptide (BNP) function

Answer 11

• ↓ blood volume through natriuresis (↑ renal Na / water excretion)
• ↓ peripheral resistance through vasodilation
• having net effect of ↓ afterload

Question 12

BNP indications

Answer 12

• indicated when heart failure is a diagnostic consideration, i.e. useful as a clue in the differential diagnosis of dyspnea
• Elevated in pts with symptomatic L or R ventricular dysfunction (either systolic or diastolic)
• BNP should be normal in noncardiac causes of dyspnea and should be quite elevated in cardiac causes of dyspnea (i.e. CHF

Question 13

BNP: what the values mean?

Answer 13

• <100 pg/mL: Negative predictive value high; basically excludes dx of heart failure; consider alternate diagnoses
• 100-400 (or 500) pg/mL: Possible dx of heart failure; history, PE, and other tests are required to improve the probability of the dx; i.e., combining BNP with clinical judgment may increase diagnostic certainty
• >400 (or 500) pg/mL: Diagnosis of heart failure is highly likely

Question 14

factors imacpting BNP

Answer 14

• BNP values tend to be higher:
  
  • Older age
  • Female sex
  • Acute and chronic renal failure
• BNP values tend to be lower:
  
  • Obesity