Cardiac Function

Question 1

lab test useful for detecting acute MI or minor myocardial injury

Answer 1

cardiac biochemical markers

Question 2

when are cardiac biochemical markers most useful?

Answer 2

when patients have non-diagnostic ECG tracings

Question 3

enzymes that catalyze similar reactions but are located in different tissues

Answer 3

isoenzymes

Question 4

an enzyme that comes from skeletal muscle, myocardium, and the brain that acts as intracellular storage of energy and muscle contraction

Answer 4

creatine kinase

Question 5

what does an elevated CK indicate?

Answer 5

MI / tissue or muscle injury

Question 6

what is the elevation characteristics of CK?

Answer 6

dramatic increase early and remains elevated for 3-4 days

Question 7

what is CK-MB highly specific for?

Answer 7

myocardial injury

Question 8

which cardiac enzyme is the first to rise after an acute MI?

Answer 8

CK

Question 9

which 3 conditions is CK-BB isoenzyme indicated for?

Answer 9

1. normal childbirth
2. malignant tumors
3. shock syndrome

Question 10

which 4 conditions is CK-MM isoenzyme indicated for?

Answer 10

1. muscular dystrophy
2. rhabdomyolysis
3. hypothyroidism
4. reye’s syndrome

Question 11

which 4 conditions is CK-MB isozyme indicated for?

Answer 11

1. heart injury
2. trauma
3. kidney injury
4. drugs

Question 12

after an acute MI, when does CK-MM return back to normal?

Answer 12

by day 3-4

Question 13

after an acute MI, when does CK-MB return back to normal?

Answer 13

by day 2-3

Question 14

a serious condition in which damaged muscle tissue releases its proteins and electrolytes into the blood

Answer 14

rhabdomyolysis

Question 15

what enzyme would be affected by rhabdomyolysis?

Answer 15

CK

Question 16

what is the contractile protein that acts as a marker of myocardial injury?

Answer 16

troponin

Question 17

where is troponin I located?

Answer 17

only in heart muscle

Question 18

where is troponin T located?

Answer 18

heart muscle and some in other muscles

Question 19

where is troponin C located?

Answer 19

heart muscle and some in other tissues, bound to calcium

Question 20

why is troponin I good to measure for a late diagnosis of myocardial injury?

Answer 20

returns to normal in 5-10 days

Question 21

what happens to troponin T, troponin I, and Ck-MB 4 hours after admission of a patient that had an AMI?

Answer 21

they increase

Question 22

what 3 interferences cause cardiac troponin to falsely increase?

Answer 22

1. microclots
2. skeletal muscle disease
3. hemolysis

Question 23

what 3 interferences cause cardiac troponin to falsely decrease?

Answer 23

1. autoantibodies
2. biotin intake
3. hemolysis

Question 24

a simple heme protein that is found in the cytoplasm of skeletal and cardiac muscles that carries oxygen to the mitochondria for oxygen storage

Answer 24

myoglobin

Question 25

what do elevated levels of myoglobin indicate?

Answer 25

tissue damage

Question 26

when does myoglobin return to normal after an AMI?

Answer 26

in 18-24 hours

Question 27

what 2 other enzymes besides CK, troponin, and myoglobin will be elevated after an MI?

Answer 27

1. AST
2. LDH

Question 28

at what LDH level will a lab perform isoenzymes?

Answer 28

greater than 180

Question 29

what ratio between the isoenzymes LD1 and LD2 indicates an AMI?

Answer 29

LD1>LD2

Question 30

what is the most common cause of rhabdomyolysis?

Answer 30

muscle injury from trauma

Question 31

what diagnostic study can be used to indicate CHF?

Answer 31

BNP