Cardiac Diagnostics

Question 1

List some cardiac labs/diagnostic tests

Answer 1

• lipid profiles (LDL = high risk for CAD)
• resting EKG (important initial test for ischemia)
• CXR (assess size)
• cardiac enzymes (rise indicates infarct)
• BNP (indicates increased ventricular volume/pressure/stretch = CHF)
• echocardiography (chamber size, fx)

Question 2

Describe the implications of HDL vs LDL in the blood

Answer 2

HDL
- protein and cholesterol
- lower risk of CAD

LDL
- carry most serum cholesterol
- deposits in arterial walls (atherosclerotic plaques)
- greater risk of CAD

Question 3

Describe what a CXR can show for a cardiac workup

Answer 3

• heart size
• lung fields (interstitial edema signs of CHF)
• pulmonary/other causes of cardiac symptoms (pneumonia, pneumothorax, PE, aortic artery dissection, tumor)

Question 4

Describe the 2 cardiac enzymes assessed in a cardiac workup

Answer 4

Myoglobin
- sensitive, not specific
- peak rise after 4-6 hrs
- normalizes after 1 day

Troponin
- sensitive & very specific
- peak rise 12-24 hrs
- normalizes after 7 days

Question 5

What can a rise in cardiac enzymes tell us

Answer 5

• infarct
• peak level correlates with amount of damage
• early levels may be normal in MI (requires serial eval)
• serial levels that are normal can rule out MI but not CAD

Question 6

Describe what brain natriuretic peptide (BNP) can tell us

Answer 6

• rise in ventricular volume/pressure and stretch
• rises in CHF
• can help distinguish CHF from other causes of dyspnea

Question 7

Describe what echocardiography can tell us in a cardiac workup

Answer 7

• chamber size, function, thickness
• L ventricular ejection fraction
• morphology & function of the valves
• can identify pericardial effusion
• transesophageal echo enables clearer visualization

Question 8

List some studies to evaluate angina

Answer 8

• stress EKG
• nuclear stress test
• stress echo
• coronary CT angiogram
• MRI
• coronary angiogram
• chemical stress tests (Dobutamine, adenosine, regadenosine)

Question 9

What is the definitive diagnostic test for CAD

Answer 9

coronary angiography aka cardiac catheterization with contrast
- visualizes the location & severity of coronary artery stenosis
- stenting/angioplasty can be performed at same time