ECG Flashcards
Conduction
Current
Vectors
Sum of current
Timing
Duration, frequency
Intervals
Segments of conduction
Patterns
Morphology
Rhythm
Fast, slow, regular, irregular
P wave
Atrial depolarization (right atrium to left atrium)
Upright in I, II, V4-V6, aVF
Inverted in aVR
Usually somewhat biphasic in V1
PR interval: beginning of P wave to start of Q wave
-usually 0.12-0.20 sec
-time from SA node to ventricular fibers
QRS complex
Ventricular depolarization=0.05-0.10 sec
Q waves typically <0.03 sec
Q wave usually small and narrow
-1-2 mm deep in I, aVL, V5, V6
->2 mm indicative of infarction, particularly in limb leads
QT duration: ventricular systole
-clinically associated with myocardial infarct or ischemia
ST segment
Just after QRS Assess distance from baseline -<1 mm in limb leads -<2 mm in precordial leads -"elevation" or "depression" when further from baseline than normal --myocardial infarction or ischemia
T wave
Ventricular repolarization
Upright in I, II, V3-V6
Usually inverted in aVR
Variable in all other leads
Slightly rounded and asymmetrical in morphology
<5 mm high in limb leads, <10 mm high in precordial leads
Inversion: usually associated with ischemia
HR on ECG
Count number of complexes in 6 seconds * 10
OR
300, 150, 100, 75, 60, 50,…
Rhythm-not present Rate-absent P wave-absent PR interval-absent QRS-absent
Asystole
Rhythm-irregular
Rate-very fast (>350 bpm) for atrial, but ventricular rate may be slow, normal, or fast
P wave-absent-erratic waves are present
PR interval-absent
QRS-normal but may be widened if there are conduction delays
Atrial fibrillation
Rhythm-regular or irregular
Rate-fast (250-350 bpm) for atrial, but ventricular rate is often slower
P wave-not observable, but saw-toothed flutter waves are present
PR interval-not measurable
QRS-normal (0.06-0.10 sec)
Atrial flutter
Rhythm-regular Rate-underlying rate P wave-normal PR interval-prolonged (>0.20 sec) QRS-normal (0.06-0.10 sec)
First degree heart block
Rhythm-regular Rate-normal (60-100 bpm) P wave-normal (positive & precedes each QRS) PR interval-normal (0.12-0.20 sec) QRS-normal (0.06-0.10 sec)
Normal sinus rhythm
Rhythm-irregular
Rate-usually normal but depends on underlying rhythm
P wave-premature, positive and shape is abnormal
PR interval-normal or longer
QRS-0.10 sec or less
Premature atrial complex
Rhythm-irregular Rate-underlying rate P wave-absent PR interval-not measurable QRS-wide (>0.10 sec), bizarre appearance
Premature ventricular complex
Rhythm-irregular but with progressively longer PR interval lengthening
Rate-underlying rate
P wave-normal
PR interval-progressively longer until a QRS complex is missed, then cycle repeats
QRS-normal (0.06-0.10 sec)
Second degree heart block type I
Rhythm-regular (atrial) and irregular (ventricular)
Rate-characterized by atrial rate usually faster than ventricular rate (usually slow)
P wave-normal form, but more P waves than QRS complexes
PR interval-normal or prolonged
QRS-normal or wide
Second degree heart block type II
Rhythm-irregular when \_\_\_\_\_\_\_\_\_\_\_\_\_\_ occurs Rate-normal or slow P wave-normal PR interval-normal (0.12-0.20 sec) QRS-normal (0.06-0.10 sec)
Sinoatrial block
Rhythm-regular Rate-slow (<60 bpm) P wave-normal PR interval-normal (0.12-0.20 sec) QRS-normal (0.06-0.10 sec)
Sinus bradycardia
Rhythm-regular Rate-fast (>100 bpm) P wave-normal, may merge with T wave at very fast rates PR interval-normal (0.12-0.20 sec) QRS-normal (0.06-0.10 sec)
Sinus tachycardia
Rhythm-regular Rate-fast (150-250 bpm) P wave- merged with T wave PR interval-normal (0.12 sec) QRS-normal (0.10 sec)
Supraventricular tachycardia
Rhythm-regular, but atrial and ventricular rhythms are independent
Rate-characterized by atrial rate usually normal and faster than ventricular rate
P wave-normal shape and size, may appear within QRS complexes
PR interval-absent: the atria and ventricles beat independently
QRS-normal, but wide if junctional escape focus
Third degree heart block
Rhythm-highly irregular Rate-unmeasurable P wave-absent PR interval-absent QRS-none
Ventricular fibrillation
Rhythm-regular Rate-fast (100-250 bpm) P wave-absent PR interval-not measurable QRS-wide (>0.10 sec), bizarre appearance
Ventricular tachycardia
