Cardiovascular Labs

Question 1

LDH1

Answer 1

heart and RBC

Question 2

LDH5

Answer 2

muscle and liver

Question 3

CPK

Answer 3

is elevated in first 24 hours and goes away after three days

• most important in ddx recurrent MI, would see a secondary spike in CPK

(troponin would remain elevated for ten days)

CPK-MM = muscle
CPK-MB - heart
CPK-BB = brain

Question 4

troponin

Answer 4

early leakage seen in MI, stays elevated for 5-10 days

• higher sensitivity tests now available
• Cardiac muscle contains specific cTnI and cTnT isoforms. Most cTn is bound, but a small amount is free in the cytosol. The initial rise of cTn after myocyte damage is thought to be release of the unbound cytosolic cTn. This is followed by more prolonged appearance of troponin from damage to the myofilament structures

Question 5

how do you ddx reinfarction?

Answer 5

elevated levels of CK-MB

Question 6

what things needed to ddx an MI?

Answer 6

elevated/falling troponin I or T

EKG changes including new onset of LBBB

chest pain

echocardiogram showing wall motion abnormality

Question 7

other things that could elevated troponin?

Answer 7

MI, pericarditis, myocarditis, PE, sepsis, LVH, CHF, CKD, DM

thus need more than just troponin elevtaion to ddx MI

Question 8

hsCRP

Answer 8

best for testing for CAD

• released by hepatocytes under influence of IL6 and TNFalpha
• if elevated more than 3 mg/L = worse prognosis for stable CHD
• best level of hsCRP <1 mg/L

Question 9

what are mediators released in inflammation?

Answer 9

• IL1, IL6 and TNF go to liver
• liver releases:
  1. fibrinogen (activation of coagulation system)
  2. Serum amyloid A
  3. CRP
  4. C3
  5. Haptoglobin

Question 10

homocysteine

Answer 10

associated with vascular injury, ASHD, coagulation, and venous thromboembol- ism, but less important than cholesterol, DM, smoking, and HTN.

Question 11

how to calculate LDL-C levels?

Answer 11

LDL-C = total-C – [VLDL-C (1/5 trig) + HDL-C]

Question 12

how to calculate Non-HDL-C levels?

Answer 12

Non-HDL-C = total C – HDL-C = cholesterol in LDL

** this is a better measurement of risk than just LDL-C alone***

Question 13

PLAQ test

Answer 13

Lipoprotein Phospholipase A2.
A lipoprotein associated, macrophage secreted enzyme.
Elevated levels lead to increased MI and stroke.
Cleaves oxidized fatty acids from LDL-C.
Levels decreased by statins.

Question 14

best supporting test for ddx of CVD?

Answer 14

cholesterol

Question 15

best marker for severity of CHF?

Answer 15

serum sodium

• high serum sodium is poor prognosis for CHF
• see hypotonic hypervolemic hyponatremia with urinary sodium less than 10

Question 16

best cardiac marker to exclude CHF?

Answer 16

NT-pro BNP levels are low

Question 17

BNP

NT proBNP?

Answer 17

if pt. comes in complaining of SOB, can use these levels, if low, to rule out CHF and to look towards resp issues

Greater than 400 pg/mL = possible CHF.

Less than 100 pg/mL = no CHF.

• NT-proBNP levels are more specific (<400 excludes CHF)

Question 18

look at slide 41 and memorize!

Answer 18

do it now

Question 19

steps of lipid metabolism?

Answer 19

• chylomicrons from diet come in and are broken up by Apo B48, ApoE, ApoCII.
• once chylomicron is broken down the liver can take up the remant and its excreted as VLDL
• VLDL is made into LDL-R by ApoB100 and Apo E3/E3 and is stored in the liver
• if don’t have ApoB48 –> results in high levels of triglycerides and creamy blood

Question 20

hyperlipoproteinemia IIa?

Answer 20

• have defective LDL receptor or defective Apo B100 ligand, which results in LDL not being taken up into the liver or fat cells
• see high cholesterol levels with high LDL-C levels
• • pt. presents with high levels LDL, corneal arcus, tendinous xanthomata, premature CAD, aortic stenosis
• ** strong family hx

Question 21

hyperliporpteouemia IIb?

Answer 21

= “familial combined hyperlipidemia”

• liver is putting out too much ApoB100 and too much VLDL
• results in high levels of triglycerides and high cholesterol (though not even)
• see NO Xanthomas,
• often seen in diabetics
• most common cause of lactescent plasma and primary hyperlipidemia

Question 22

hyperlipoproteinemia III?

Answer 22

• due to defective inherited Apo E3/E3 (instead have E2/E2)
• see equal amounts of cholesterol and triglycerides
  _“dysbetalipoproteinemia = E2/E2
• see weird xanthoma rash on hands and elbows

Question 23

what are markers of CHD?

Answer 23

coronary heart disease stratification = Identify CHD equivalents (DM, TIA, PAD, AAA, 10-year risk of CHD > 20%). If present, the cholesterol goal is HDL-C < 100 mg/dL, with an optional goal of < 70 mg/dL

age, total cholesterol, smoking, HDL cholesterol, BP.
also considered to evaluate risk