Cardio GW Flashcards
Atrial depolarization
P wave
AV slowing pulse down
PR interval
Ventricular depolarization
QRS wave
Rest period between depolarization and repolarization of vent
ST segment
Repolarization of ventricles
T wave
Depression of ST segment means
decreased blood flow to myocardium
Indicated myocardial ischemia
Elevated ST segment may mean
Acute MI
What is hibernating myocardium
severely, chronically ischemic tissue that is viable but appears to be nonfunctioning and has decreased perfusion
-high likelihood of benefiting from revascularization
What is myocardial stunning
A temporary response where the myocardium is deprived of blood flow.
Occurs after the pt experiences acute episode of severe ischemia or an acute MI that is terminated by thrombolysis or revascularization
Myocardial perfusion imaging RPs
Tl201 thallous chloride
99mTc Sestamibi
99mTc Tetrofosmin
Rb82 chloride, N13 ammonia, F18 FDG
Exercise prep
Fast for at least 3 hours prior
No physical exertion 12 hours prior
Drugs that can affect exercise
Beta blockers 72 hrs
Calcium channel blockers 48-72 hours
Antihypertensives 4-7 days
Anti arrhythmic agents 2 days
Sedatives 1 day
Nitroglycerin 1 hr
Long acting nitrates 12 hr
Digitalis (digoxin) 1-2 weeks
Target heart rate calculation
(220 - pts age) x 85%
Right and left arm electrode placement
Midclavicular line, below clavicle
Rt and left leg electrodes are placed where
Just below rib cage on either side
Pharmacological stress test prep
NPO minimum 4 hours prior
D/C xanthine derivatives 12-24 hours
No caffeine 12 hours prior
If possible, aminophylline should not be administered until ____ minutes after tracer
1-2 minutes
Can cause false positive if injected too early
1-6 EKG placement
1 - fourth intercostal space on left side of sternum
2 - fourth intercostal space on right side of sternum
3 - in between 2 and 4
4 - fifth intercostal space directly below midclavicular line
5 - right beside or 4 at left anterior axillary line
6 - right beside or 4 at left midaxillary line
Dipyridamole (Persantine) contraindications
Bronchospasm, pulmonary disease, active wheezing, hypotension, severe mitral valve disease
MI within 2 days, unstable angina within 48 hours, severe aortic stenosis, severe obstructive hypertrophic cardiomyopathy, and severe orthostatic hypotension
Contraindications for adenosine
Same as dipyridamole +
Second or third degree AV block (without pacemaker)
If patient is taking oral dipyridamole for heart medication and needs stress test
Cannot give adenosine
Must d/c dipyridamole 2 days before regadenoson
Contraindications for regadenoson
2nd or 3rd AV block (without pacemaker)
Bronchospasm, low BP, hypersensitivity to reg.
Contraindications for exercise
LBBB
Combination of low level or isometric exercise with dipyridamole, adenosine, or regadenoson (during or after drug) has what benefits
Decreased side effects
Decreased sub diaphragmatic uptake
Increased target to background ratio
Dobutamine stimulates what receptors
B1
Dobutamine is indicated for
Pts who cannot exercise and cannot undergo pharmacologic stress due to severe bronchospastic disease
Pt prep for dobutamine
NPO at least 4 hours
Withhold beta blockers for 24-48 hours
Contraindications for dobutamine
Recent MI less than 1 week, unstable angina, critical aortic stenosis, atrial tachyarrhythmias, v-tach, uncontrolled HBP, aortic dissection, large aortic aneurysm
Planar MPI, a zoom factor of _____ should be used if using large FVOC
Zoom factor of 1.2-1.5
Diaphragmatic attenuation on planar MPI may cause
False positive defect in inferior wall of left ventricle
Quantitative myocardial perfusion information on planar imaging
Circumferential profile analysis
Heart to lung ratio things to remember
Same size ROIs
The myocardial ROI should not be placed on the anterior or anteriolateral wall because of heart/lung overlap