E1: Enzymes, Labs & Diagnostics

creatine kinase (CK)

released when muscle is damaged
CK-MB → heart
CK-BB → brain
CK-MM → skeletal muscle

When does CK-MB appear, peak and return normal?

Appears: 6-12 hours

peaks: ~ 24 hours

Returns to normal: 3-4 days (limitation)

Troponin are useful in detecting ______

small infarcts

What cardiac enzyme is the most specific for MI?

Troponin I

When does Troponin I appear and return normal?

Appears: 1-3 hours
Remains: 14-15 days

where is myoglobin found?

striated muscle (heart & skeletal)

when is myoglobin released?

when skeletal or cardiac muscle is damaged

When does myoglobin level appear, peak and return normal?

Appears: 2 hours after MI
peaks: 6-8 hours
Returns to normal: 20-36 hours

Why is myoglobin levels sensitive, but not specific for MIs?

Because it appears within 2 hours but could also be elevated due to damaged skeletal muscle

Why is lactic dehydrogenase (LD) not very helpful in the detection of MIs?

It is found everywhere in the body (not specific to heart)
- found in heart & skeletal muscle, liver, erythrocytes, kidneys

when does LD level appear, peak and return to normal?

appears = 24 hours
peaks = 3 days
returns = 8-9 days

what is the first line and second line test to rule out an MI?

first line = troponin I
second line = CK

What is a normal BNP level?

< 100

What is a BNP used for?

CHF (emergency setting)

when is BNP produced?

↑ ventricular stretch and volume (HF)

what does ↑ BNP result in?

vasodilation, natriuresis, diuresis and ↓ preload

BNP has high _______ and low ______

High sensitivity, but low specificity

Does an elevated BNP rule in heart failure?

NO (low BNP does rule out heart failure)

CXR is used to assess?

heart size, pulm vasculature, calcification and heart failure

What is used to evaluate arrhythmias over a 24 hour period?

Ambulatory cardiac monitoring (Holter monitor)

what is a 2D echo used for?

noninvasive technique used to assess heart position, size, movement of valves, chambers and velocity of blood flow

what is a 2D echo indicated for?

suspected valve, chamber disturbances, evaluation of pericardial effusion

How does a patient lay for a 2D echocardiogram?

Left lateral decubitus

2 types of 2D echo

TTE (default) & TEE (more invasive)

when do you used a TEE?

when you want to look at the left side of the heart (LV & mitral)

If a Homan test is positive, what is your next step?

Doppler US

A Carotid Intima Media Thickness (CIMT) is used to detect the presence or absence of ______

Atherosclerotic disease (and degree of plaque burden)

CIMT can predict _______

future cardiac and cerebrovascular events

A Carotid Intima Media Thickness (CIMT) can distinguish between _________

Different types of plaque which provides information about stable & unstable plaques

Most post-MI patients once stable have a ______ prior to discharge to stratify their risk for any recurrent MI

Stress test

what test is used in stress tests?

EKG or ECHO (or both)

when should a MRI be avoided?

pts w implanted devices & first 12 weeks of pregnancy

multiple-gated acquisition scan (MUGA) is used to assess _______

the function of the heart → CO, LVEF, velocity & wall abnormalities

what is injected in the pt during a MUGA scan?

Tch-99 RBCs

SPECT vs PET (not on exam??)

SPECT = identifies blockages, determines if there was a previous MI or if at risk for MI, assess condition after bypass

PET = looks for CAD via evaluating heart function, assesses damage after MI

What is the Coronary Artery Calcium (CAC) score used for?

Stratify risk of coronary heart disease in asymptomatic patients

As the CAC score rises, so does ________

CV risk

what is a CAC score of < 1?

no identifiable disease

What is a CAC score of 1-10?

Mild

What is a CAC score of 11-100?

Moderate

What is a CAC score of 101-400?

Moderate to high

What is a CAC score of > 400?

Severe

What is a tilt table test used for?

Identify cause of syncope/orthostasis

if a patient exhibits syncope during tilt test it is assessed to be ______

neural mediated and NOT cariogenic

Electrophysiologic studies (EPS) are used to _______

Detect and analyze arrhythmias and their origins

Used as a noninvasive method for detecting blockages in the coronary arteries

Coronary CTA

What 3 major measurements are obtained by cardiac ventriculography?

EF, SV, CO

what is the best way to diagnose HTN?

home or continuous ambulatory BP monitoring (ABPM aka CABP)

CTA is used to obtain _______

high-resolution 3D pictures of the moving heart and great vessels