EKG Basics
Text Outline
EKG graph paper:
Small square = 1 mm or 0.04 sec
Large square = 5 mm or 0.2 sec
Normal values:
· Heart Rate: 60 to 100 beats/min
· P Wave: width < 3 small boxes (0.12 sec) and height < 2.5 small boxes (0.25 mv)
· PR Interval: 3 to 5 small boxes (0.12 to 0.20 sec)
· QRS duration: < 3 small boxes (0.12 sec)
· T wave: < 5 small boxes in limb leads, < 10 small boxes in precordial leads
Heart rate estimation:
· Regular rhythm: Division of 300 by number of large squares between consecutive R waves
· Irregular rhythm: Number of QRS complexes (R waves) on the EKG strip x 10
Rhythm analysis:
· Regular rhythm: Interval between R waves is constant or varies by < 1.5 small boxes
· Irregular rhythm: Interval between R waves varies by > 1.5 small boxes
Systematic Interpretation:
· Read EKG strip from left to right
· Seven step approach
o Calculate heart rate
o Check rhythm
o Assess P Wave
Present or absent?
Occurring regularly or irregularly?
P wave before each QRS or not?
Shape
o Measure PR interval
Beginning of P wave to onset of QRS complex
o Measure QRS duration
Beginning of Q wave to end of S wave
o Look at ST segment
Elevated, depressed or isoelectric to TP segment?
o T waves
Tall, inverted or biphasic?
· Normal sinus rhythm
· Sinus bradycardia
· Sinus tachycardia
· Sinus arrhythmia
· Sinus pause/arrest
· Atrial flutter
· Atrial fibrillation (AFib)
· Supraventricular tachycardia (SVT)
· Premature atrial complexes (PACs)
· Multifocal atrial tachycardia (MAT)
· Ventricular tachycardia (VT)
· Premature ventricular complexes (PVCs)
· Torsades de Pointes
· Ventricular fibrillation (VFib)
Conduction blocks: <=click link
· First degree AV block
· Second degree AV block:
o Mobitz type I
o Mobitz type II
· Third degree AV block
· Right bundle branch block
· Left bundle branch block
EKG in myocardial infarction (MI): <=click link
· Criteria
· Contiguous leads
· STEMI evolution
· Old MI