Cardiac Laboratory and Diagnostics (Exam 2) Flashcards
Describe lipid profiles and the indications for use.
Men 35 or older and women 45 or older (not recommended in those older than age 75.
Describe what a resting EKG is and the indications for use.
It is most important initial test for ischemic heart disease. Classic findings: reversible ischemia (angina): ST depression, T-Wave flattening/inversion.
Acute MI: ST elevation followed by Q waves. A completely normal EKG doesn’t exclude angina or acute MI.
What is the indication for use of a stress EKG?
evaluate for angina/ischemia-used to induce myocardial ischemia when not present at rest. Patients with suggestive symptoms, high-risk patients (hyperlipidemia, DM), patients with strong family history of early CAD, older patients beginning strenuous activity program. Often combined with radionuclide or echo.
Describe a stress EKG.
Exercise on treadmill or stationary bike
various protocols (most common is “Bruce”
Positive test: ST depression >/= 1 mm
Positive test usually followed by coronary angiogram.
Describe a chest X-ray and indications for use.
Often normal in patients with ischemic heart disease.
Assess for:
heart size (cardiomegaly)
lung fields for interstitial edema (sign of CHF)
Indicated for those with chest pain or shortness of breath.
What is the indication for use of cardiac enzyme tests?
Enzyme rise indicates irreversible myocardial cell damage. Normal serial enzymes rule out acute MI, but do not rule out coronary artery disease-chest pain may still be due to unstable angina. Peak level of enzymes correlate with amount of myocardial damage.
Describe a cardiac enzyme test.
Myoglobin: very sensitive, not specific. early rise: 1-2 hours. Peak: 4-6 hours. Normalize 1 day.
Troponin: still quite sensitive and very specific for MI. early rise: 3-6 hours. Peak: 12-24 hours. Normalize: 7 days.
What is the indication for use of Brain Natriuretic Peptide (BNP) testing?
Helps distinguish CHF from other causes of dyspnea.
Describe a BNP test.
A polypeptide secreted by cardiac ventricles in response to increased ventricular volume/pressure-rises in CHF
Describe Stress radionuclide studies and when they are used.
Used to detect coronary artery disease, reversible ischemia, or old/recent MI. A radionuclide is injected during exercise. A zone of hypoperfusion may indicate reversible ischemia or scar. If reversible, perfusion defects will fill in during rest period. If old, perfusion defects persist despite rest.
What are the indications for use of a multiple-gated blood pool imaging (MUGA scan)?
calculate left ventricular ejection fraction-patients getting chemo may get scan to make sure no cardio side effects from chemo. Look for focal wall motion abnormality after MI. Look for temporary wall motion abnormality with exercise (reversible ischemia).
Describe a MUGA scan.
Red blood cells are labeled with technetium-99. The heart is imaged through several hundred cardiac cycles to provide clear image of the heart throughout the cycle.
What are the uses of a PET scan?
Distinguishes stunned myocardium from scar by showing persistent metabolism in areas of reduced blood flow.
Describe a PET scan.
Uses positron emitting agents to show perfusion/glycolytic metabolism of myocardium.
How does echocardiography work?
Demonstrates chamber size, function, thickness-left ventricular ejection fraction (important prognostic indicator). segmental “wall motion abnormalities”
How is echocardiography used?
wall abnormalities indicate ischemia or prior MI. Identifies pericardial effusions.
What is a two-dimensional echocardiogram?
cross-section of cardiac structures
What is a color-flow doppler?
measures speed and direction of cardiac blood flow. detects valvular regurgitation
What is a transesophageal echo (TEE)?
Transducer passed into esophagus. enables clearer visualization of cardiac structures-can be useful for detecting vegitations of the heart valves or blood clots forming on the valves.
Describe a stress echo and when it should be used.
Performed at rest and with exercise.
wall motion abnormalities indicate either reversible ischemia or prior infarction.
Reversible ischemia: produces exercise-induced wall motion abnormalities (defects are present only with exercise).
Prior MI: “fixed defect” that is present with both rest and exercise.
What do you do if a person can’t do a stress test because of their inability to do the physical work?
Pharmacologic induced stress: adenosine
Describe a coronary CT angiogram (CCTA).
Noninvasive method to image coronary arteries. Downside is radiation. If the test is negative there is certainty that there is no issues. Sensitivity: 95% Specificity 60-90%-may look more occluded than it actually is.
What are the indications for use of a CCTA?
Symptomatic patients at intermediate risk for CAD.
Equivocal/nondiagnostic stress test.
What is a cardiac MRI used for?
Usually research but being investigated fo possible use of imaging coronary arteries for CAD.
Describe a cardiac MRI.
Provides excellent anatomic definition of heart
-myocardial thickness
-chamber size
-many congenital defects
Rapid sequence MRI shows LV function and wall motion (useful if echo is suboptimal)
What are the indications for use of Cardiac Catheterization?
patients being considered for angioplasty/stent or coronary artery bypass grafting (CABG) because of:
- anginal symptoms not responding to medication
- unstable angina
- non-invasive tests demonstrate high-risk disease
- recurrent symptoms in pt with prior angioplasty or CABG
- Pts surviving sudden death from life-threatening arrhythmiain which CAD may be the cause
- chest pain or cardiomyopathy of unknown cause
- acute MI in ER
Describe a cardiac catheterization.
Gold standard-the definitive diagnostic test for CAD. Selective catheterization of coronary arteries followed by injection of contrast. Visualizes location and severity of coronary artery stenosis. Angioplasty/stenting can be performed as part of same procedure.
Why is cardiac catheterization not typically first line for diagnostic testing?
Really expensive and invasive.
What is a holter monitor?
portable cardiac monitor worn by pt to record cardiac activity for 24-48 hours.
what is an event monitor?
records only when patient activates it (when patient is experiencing symptoms). preferable when symptoms are infrequent and might not be caught in a 24 hour period.
What is ambulatory EKG monitoring used for?
useful in diagnosis of arrhythmias: symptoms are often not present at time of office/hospital evaluation. can demonstrate the arrhythmia present at the time the symptoms occur.
