Cardiac Function Flashcards
lab test useful for detecting acute MI or minor myocardial injury
cardiac biochemical markers
when are cardiac biochemical markers most useful?
when patients have non-diagnostic ECG tracings
enzymes that catalyze similar reactions but are located in different tissues
isoenzymes
an enzyme that comes from skeletal muscle, myocardium, and the brain that acts as intracellular storage of energy and muscle contraction
creatine kinase
what does an elevated CK indicate?
MI / tissue or muscle injury
what is the elevation characteristics of CK?
dramatic increase early and remains elevated for 3-4 days
what is CK-MB highly specific for?
myocardial injury
which cardiac enzyme is the first to rise after an acute MI?
CK
which 3 conditions is CK-BB isoenzyme indicated for?
- normal childbirth
- malignant tumors
- shock syndrome
which 4 conditions is CK-MM isoenzyme indicated for?
- muscular dystrophy
- rhabdomyolysis
- hypothyroidism
- reye’s syndrome
which 4 conditions is CK-MB isozyme indicated for?
- heart injury
- trauma
- kidney injury
- drugs
after an acute MI, when does CK-MM return back to normal?
by day 3-4
after an acute MI, when does CK-MB return back to normal?
by day 2-3
a serious condition in which damaged muscle tissue releases its proteins and electrolytes into the blood
rhabdomyolysis
what enzyme would be affected by rhabdomyolysis?
CK
what is the contractile protein that acts as a marker of myocardial injury?
troponin
where is troponin I located?
only in heart muscle
where is troponin T located?
heart muscle and some in other muscles
where is troponin C located?
heart muscle and some in other tissues, bound to calcium
why is troponin I good to measure for a late diagnosis of myocardial injury?
returns to normal in 5-10 days
what happens to troponin T, troponin I, and Ck-MB 4 hours after admission of a patient that had an AMI?
they increase
what 3 interferences cause cardiac troponin to falsely increase?
- microclots
- skeletal muscle disease
- hemolysis
what 3 interferences cause cardiac troponin to falsely decrease?
- autoantibodies
- biotin intake
- hemolysis
a simple heme protein that is found in the cytoplasm of skeletal and cardiac muscles that carries oxygen to the mitochondria for oxygen storage
myoglobin
what do elevated levels of myoglobin indicate?
tissue damage
when does myoglobin return to normal after an AMI?
in 18-24 hours
what 2 other enzymes besides CK, troponin, and myoglobin will be elevated after an MI?
- AST
- LDH
at what LDH level will a lab perform isoenzymes?
greater than 180
what ratio between the isoenzymes LD1 and LD2 indicates an AMI?
LD1>LD2
what is the most common cause of rhabdomyolysis?
muscle injury from trauma
what diagnostic study can be used to indicate CHF?
BNP
