Electrocardiogram (ECG) Flashcards
P wave
Atrial depolarization
PR interval
Time for atrial depolarization and conduction fro SA node to AV node
PR interval time
0.12-0.20 s
QRS complex
Ventricular depolarization and atrial repolarization
QRS complex time
0.06-0.10
QT interval
Time for both ventricular depolarization and repolarization
QT interval time
0.20-0.40
ST segment
Period when ventricles are depolarized
T wave
Ventricular repolarization
Normal sinus rhythm
60-100 bpm
Sinus bradycardia
<60 bpm
Sinus tachycardia
> 100 bpm
Sinus arrhythmias
Sinus rhythm, quickening and slowing of SA node impulses, beat-to-beat variation
Sinus arrest
Sinus rhythm with intermittent failure of SA node or AV node with occasional complete absence of P wave or QRS complex
Premature atrial contractions (PAC)
Ectopic focus initiates impulse before the SA node
P wave is premature
Benign, occurs with caffeine, stress, smoking, alcohol
Atrial flutter
Ectopic atrial tachycardia 250-300 bpm
Sawtooth shaped P waves
Occurs with valvular disease (esp mitral)
Atrial fibrillation
Atrial depolarize 350-600 bpm
Irregular undulations without discrete P waves
CAD, HTN, valve dx
1st degree AV block
PR interval is longer that 0.20 sec but constant
May be due to meds
2nd degree AV block: Mobitz I
Progressive prolongation of PR interval until one impulse is not conducted
Benign
2nd degree AV block: Mobitz II
Consecutive PR same/normal followed by nonconduction of one or more impulses
↓ CO= more serious
May progress to 3rd degree AV block
3rd degree AV block
All impulses at the AV nodes are blocked, no impulses sent to ventricles
Atria and ventricles are paced interdependently
atrial rate > ventricular rate
*medical emergency= steep ↓ of CO
Premature ventricular complex (PVC)
Ectopic focus causing premature ventricular depolarization
QRS wide and aberrant
May be asymptomatic/palpitations
Ie anxiety, caffeine, etc
Unifocal PVCs
same ectopic focus + same config
Multifocal PVCs
arise from different foci + different config
Bigemy
Normal sinus impulse is followed by a PVC
Trigeminal
PVCs occur after every two sinus impulses
Ventricular tachycardia (v-tach)
3 or more consecutive PVCs at a ventricular rate >150 bpm
QRS complexes are wide and aberrant
Those > 30 sec are life threatening 2 º hypotension
Ventricular fibrillation (v-fib)
Ventricles do not beat in a coordinated fashion
No CO = unconscious
Lethal and requires immediate defibrillation
Ventricular asystole
No rhythm
Straight-line pattern
Immediate CPR and meds needed
ST segment depression
Sign of subendocardial ischemia, digitalis toxicity, hypokalemia
Evaluated at J point
ST segment elevation
Earliest sign of acute trans mural infarction
Benign sign of early repolarization
Q-wave
Characteristic sign of infarction
T-wave inversion
Occurs hours/days after MI as a result of a delat in repolarization
