BIOCHEMISTRY: CARDIOVASCULAR Flashcards
What is cardiovascular disease (CVD)?
describes any disorder of the heart and circulatory system
most common: coronary artery disease & stroke
What is coronary artery disease?
- build up of of fatty deposits and cholesterol on the inner walls of the artery.
- can lead to stenosis (narrowing of artieries) or blockage
- 12 hours cell death – necrosis in effected area
- called heart attack/myocardial infarction (MI)
How can MI be diagnosed?
- history – symptoms/timing
- blood test – screens for cardiac biomarkers
- ECG/EKG
- Nuclear scan
- Coronary angiography (or arteriography)
Why are the symptoms in diabetes patients sometimes silent?
b/c of nerve damage
What are cardiac biomarkers?
enzymes/proteins which are assayed to assess the health and physiological state of the heart.
- indcates amount of damage done to the heart
- level of specific enzyme/protein correlates w/ tissue damage
Why are biomarkers important?
- help diagnose/stratisfy risk and monitor/manage damage
- help estimate severity of heart attack
How does necrosis and inflammation effect serum proteins and enzyme levels?
The presense of serum proteins/enzymes indicates tissue or celluralr damage has occured resulting in the release of intracellular components into the blood
What are past cardiac biomarkers of the past and why are they no longer used alone to diagnose MI?
- Lactate dehydrogenase (LD or LDH)
- Aspartate aminotrasferase (AST)
- Myoglobin
- Creatine kinase (CK)
They are no longer used because they are non-specific
What are isoenzymes of lactate dehydrogenase (LD or LDH) and where are the isoenzymes found found?
Why can’t we use this biomarker for MI now?
Why was it used in the past?
LD1 - LD5
- pancrease, kidneys, stomach, & red blood cells (RBCs) all contain LDH-1
- Platelets contain LDH-2, LDH-3, & LDH-4
Can’t use this biomarker for MI b/c cardiac tissue contains LDH-1 & LDH-2.
It was used in the past b/c LDH levels would rise ~10 hrs, peak 24-24hrs and remain elevated for upto 8 days
Why is Aspartate aminotrasnferase (AST) no longer used and where can you find high concentrations of it?
- non specific and found in the heart and liver
- also called serum glutamate oxaloacetate (SGOT)
- also catalyzes the reversible transfer of an alpha-amino group b/w aspartate and glutamate (amino acid metabolism)
Why is myoglobin no longer used as a biomarker for MI?
- short half-life (rapid metabolism)
- non specific for cardiac muslce (also found in skeletal muslce)
increases more rapidly than creatine kinase
heme-protein present in the heart/skeletal muscle
oxygen carrier
can be used together w/ troponins and/or CK-MB
The cardiac biomarker creatine kinase (CK) aka creatine phosphokinase (CPK) is not longer used because it’s also present where?
What reversible reaction does it catalylize?
What are the subunits it’s made of and what isoenzymes can it form?
- found in skeletal muscle, myocardium and brain
- creatine to phosphocreatine (makes ATP/ADP) resevoir for energy b/c it’s reversible
- two subunits are –B & –M that can make CK-MM (muscle), CK-BB (brain) and CK-MB (heart)
Why is CK-MB used as a cardiac biomarker?
- highly specific to cardiac tissue
- levels rise 3-6 hours after MI
- peaks 12-24 hours after MI
- returns to baseline 48-72 hrs after MI
if the levels return to normal and rise again could be re-infarction
Explain the CK: CK-MB ratio
It was a ratio proposed for use to diagnose MI. The higher the ratio of CK-MB to CK, the more likely MI occured
if ratio is grearter than 2.3 - 3, proposed MI
Why is troponin C not used?
because it doesn’t have an isoform that is specific to the heart
it can come from heart or skeletal muscle
