EKG Flashcards
P wave
atrial depolarization
QRS complex
ventricular depolarization and atrial repolarization
T wave
ventricular repolarization
PR interval
movement of electrical activity from atria to ventricles
normal PR interval
0.12 - 0.20
what is happening in the PR interval
time impulse travels from SA node through internodal pathways in atria toward ventricles
long PR interval
greater then 0.20 seconds
indicates the impulse was delayed as it passed through atria, AV node, or AV bundle
short PR interval
less than 0.12 seconds
may be seen when the impulse originates in the atria close to the AV node or in the AV bundle
QRS complex represents
conduction of impulse form Bundle of HIS through ventricular msucle
normal QRS complex
0.12 seconds
0.12 seconds = ___ small boxes
3
R-R interval
ventricular rate and regularity
QT interval
time take from ventricles to depolarize, contract, and repolarize; represents total ventricular activity
ST segment
time between ventricles depolarized and repolarization of ventricles begins (ventricular contraction)
T waves
“resting phase” of cardiac cycle
Most important assessment other or while doing ECG
looking at your patient and there presentation
8 step ECG interpretation
(1) measure HR
(2) examine R-R interval
(3) examine P wave
(4) measure PR interval
(5) determine if each P wave is followed by QRS
(6) examine and measure QRS
(7) examine and measure QT
(8) diagnose the rhythm
six-second method
count the number of complete QRS complexes within a period of 6 seconds and multiply it by 10 to determine the number of QRS complexes in 1 min
Sinus Bradycardia
HR less than 60
originates from SA node
treatment for sinus bradycardia
atropine / pacemaker
sinus tachycardia
rate greater than 100bpm and less than 150bpm
what causes sinus tachycardia
sympathetic stimulation, fever, hypovolemia, pain
treatment for sinus tachycardia
beta blockers, calcium channel blockers, vagal nerve stimulus, antipyretics, pain management, antianxiety measures, carotid artery massage
sinus node dysfunction
impulses originate elsewhere in atria
- premature atrial contractions
- SVT
- may decrease cardiac output secondary to tachycardia
Atrial dysrhythmias
characterized by rapid atrial rate
- rapid ventricular response to symptoms
PAC’s
often benign but may be warning sign for something else
- enhanced automaticity of cardiac cells
sinus arrhythmia
rate 63-81 bpm
who is sinus arrhythmia common in
athletes and children
atrial fibrillation
atria contracting very rapidly, unable to empty, discharging greater than 400bpm
- absent P waves
what happens in afib
- atrial chambers are unable to refill before contraction
- inadequate ventricular filling
- decreased stroke volume by 25%
- blood in atria prone to form clots
- increase risk for thrombotic stroke
supraventricular tachycardia (SVT)
- rate between 150 and 250 bpm
- regular rhythm
- undistinguishable P wave
- QRS complex normal
- R-R irregular
treatment for SVT
valsalvas maneuver, calcium channel blockers, digoxin, beta blockers, adenosine, cardioversion
atrial flutter
- rate greater than 250 (up to 350)
- ventricular rate regular or irregular
- atrial oscillations appear as saw tooth or flutter waves
-ventricular rate ~80, atrial rate ~375 - QRS complex 0.10
treatment for atrial flutter
cardioversion, calcium channel blockers to regulate HR, digoxin, beta blockers
heart blocks are like __________
relationships
first degree AV block
- PR interval > 0.20 seconds
- delayed conduction through AV node
- pt usually asymptomatic; no treatment necessary
- related to acute MI, CAD
second degree AV block
SA node impulse conduction is delayed or completely blocked
- occurs in AV nodal area
- P wave is present
- PR interval is irregular or not measurable
difference between second degree AV block type 1 and type 2
Type 1 - P and QRS are far apart and then close together again
Type 2 - P and QRS are normal, but P sometimes moves father or closer
junctional dysrhythmias
- SA node fails to fire
- intrinsic rate 40-60 bpm
- AV node become pacemaker
- inverted or absent P wave
ventricular dysrhythmias
- life threatening
- inadequate ventricular ejection
- insufficient stroke volume
- decrease cardiac output
- decrease tissue perfusion
ventricular bigeminy
- beats originate in the ventricles
- regular pattern
- may lead to v tach or v fib
treatment for ventricular bigeminy
O2, antiarythmatics
ventricular tachycardia
- 3 or more PVC’s occurring at a rapid rate, usually greater than 100bpm
- may deteriorate into ventricular fibrillation
ventricular fibrillation
- most common cause of sudden cardiac arrest
treatment for ventricular fibrillation
defibrillation is treatment of choice and epinephrine
asystole
- represents complete cessation of electrical impulses
- terminal rhythm
