Heart Flashcards
Natriuretic Peptides
generally function to inhibit the reabsorption of sodium in the renal tubule so that sodium excretion in urine is increased
ANP
BNP
CNP
BNP
Brain Natriuretic peptide
first discovered in the Brain, but it is actually released from the ventricles when they stretch out.
BNPs cause vasorelaxation and increase water and sodium excretion
Used in diagnosis of CHF- strong correlation with Left Ventricular pressure
The higher the value, the more likely it is CHF or MI. Greater than 500 is essentially CHF.
Normal value less than 100pg/mL
(Don’t confuse with the BMP, basic metabolic panel)
Not a good tool if the patient is in renal failure
CK
Creatine Kinase
an enzyme that helps convert creatine to phosphocreatine–> energy in stress situations
Mostly found in high energy tissues, Cardiac, skeletal muscle, brain
exists in 3 different isoenzymes
CK-MM
found mostly in skeletal muscle- most CK is in this form
people with larger muscle mass tend to have higher baseline CK
CK-BB
mostly in brain
CK-MB
mostly in the heart
rises 3-6 hours after myocardial infarction, not elevated in all patients until 12 hours and returns to baseline in 36-48 hours
used to be the marker for MI, but we have better tests now. NOT the preferred test, but still sometimes gets ordered though!
Troponins
the GOLD STANDARD for MI detection. It rises FASTER and stays around longer.
To diagnose acute coronary syndrome or myocardial injury
-When troponin is bound by calcium, it allows exposure of the myosin binding sites on actin.
- There are different troponin subsets: Cardiac troponin I used more commonly than T because renal failure more frequently increases Cardiac troponin T
Troponin C is not used to detect MI
Myoglobin
a relative of Hb, but is only in skeletal and cardiac muscle. It is a short term O2 storage in muscle.
-It only releases into bloodstream when there is a skeletal or cardiac injury
realeases w/in 3 hours.
More sensitive than CK-MB but is is not as specific to just cardiac
LDH
Lactate dehydrogenase
catalyzes the conversion of lactate to pyruvate→ involved in energy production in cells
Not specific- in many tissues, but it is released during tissue injury.
There are 5 different isoenzymes, 1-5, and LDH-2 is the most abundant, EXCEPT in MI, then LDH-1 is more abundant
Not as useful as troponin, but the benefit is that it can be ordered 48 hrs after injury
D-Dimer
a bi-product of clot formation. Generally it is non-detectable.
Increased D-Dimer is an indication of intravascular clotting. When you see this, ask yourself does this person have a clot somewhere?
DVT (deep vein thrombosis) or PE (pulmonary embolism)
should be used with other tests to diagnose DVT or PE
CRP-HS
C-reactive protein is an acute phase reactant
can increased and then decrease a lot in cases of inflammation- an inflammatory mediator.
It is produced in the liver, but it is not specific. Often used to monitor a pt with strong hx of cardiovascular disease–> are they going down that path?
Lipid panel
Useful in evaluating patients for hyperlipidemia, see if they have a risk for CHD
There is a linear relationship between CHD and hyperlipidemia!
Demonstrates which patients benefit from statin therapy, aspirin and other life-saving treatments
LDL
Low density Lipoprotein- this is bad, you want it to be LOW. This carries a lot of cholesterol, 75%
HDL
High density Lipoprotein, this is good, you want it to be HIGH. This carries less cholesterol, 25%, more protein in comparison to LDL.
Takes cholesterol back to the liver
Men at risk if below 40
Women at risk if below 50
Who do we screen for lipid panel?
Men at age 35+ or if they have risk factors, or a family Hx
Women at 45+ (estrogen confounding factor),, or sooner if risk factors or family hx
Diabetics- annually
High risk patients with one or more, or one severe of: Smoking, Hypertension, Family Hx
Total Cholesterol
sum of LDL, HDL and VLDL- want below 200
Triglycerides
made in the liver, they are fatty acids and glycerol combined
these are an energy source for the body.
ideally, you want this below 150
diabetics frequently have high triglycerides, very high is over 500
LDL particle testing
Calculates how many particles of LDL you have, and how big they are- the smaller and denser are more dangerous because they can attach to the arterial wall better.
More ideal, of your LDL, you want big and fluffy vs small and dense.
This is done via gel electrophoresis
Gone out of favor for testing because it is an added expense.
CK normal
50-200 units/liter
Total CK increase in
strenuous exercise
recent surgery
Rhahbdo
Troponin I normal
Cardiac troponin I:
Troponin T normal
Cardiac troponin T:
D-Dimer normal
Normal value:
Lipid panel components
Total cholesterol
Triglycerides
LDL
HDL
Lipid panel guidelines
If initial test is clearly normal → test every five years
If initial test borderline → test every three years
In patients over age 65 who have had more than 1 screening in past, it is reasonable to stop screening.
Generally should be measured while fasting
Triglycerides high in
Familial hypertriglyceridemia
Hyperlipidemia
High carbohydrate diet
Poorly controlled diabetes
HDL high in
Familial HDL lipoproteinemia Exercise Moderate alcohol use Healthier eating choices Estrogen administration
HDL low in
Metabolic syndrome
Genetically low HDL
Friedewald formula
LDL calculation
LDL= Total cholesterol - (HDL+TG/5)
*only valid if TG, triglycerides, is below 400
LDL levels
if you are already at risk for HD, you want this below 100
Greater than 160 is bad
LDL high in
Familial LDL lipoproteinemia
LDL low in
Exercise
Low fat diet
LDL pattern A
Large particle size
LDL pattern B
Small, dense particle size
Higher ability to enter walls of blood vessel and increased risk of CHD
LDL pattern I
Intermediate particle size
