ECG rhythms Flashcards
How to identify:
LBBB
QRS >120ms
QRS downwardly deflecting in V1
Normal Sinus rhythm
Regular
Rate 60-100 bpm
PR interval 120-200 ms (3-5 small squares)
P wave precedes each QRS complex
QRS 80-120 ms (2-3 small squares)
Sinus tachycardia
Regular
Rate >100 but <150 bpm
Popping P waves
Each P followed by QRS
PR normal and constant
Sinus Bradycardia
Regular
Rate <60 bpm
Popping P waves
Each P followed by QRS
PR normal and constant
Atrial ectopics
Originates from a focus in the atria
Usually P wave is abnormal in shape - Not Popping
Usually normal QRS
Followed by a compensatory pause
Atrial Fibrilation
Irregularly Irregular
No P waves
Rate may be slow, normal or fast
QRS usually normal
Atrial Flutter
Usually regular
No popping P waves
Flutter waves - saw tooth appaerance
Atrial rate around 300bpm
Narrow Complex Tachycardia
rate >100 (usually >150 bpm)
regular
QRS normal (narrow equal to or <120 ms)
Absence of P waves
Ventricular Tachycardia
Very broad complexes (>160ms).
Heart block:
1st degree
Regular
popping P’s
Each followed by QRS
QRS normal
PR interval prolonged and constant
Usually benign except in combination with other blocks
Heart Block:
2nd degree AV block
mobitz type I (wenckebach AV block)
Irregular
Can be slow/normal
Popping P’s
PR interval progressively lengthens
until P wave is not followed by QRS
Life in the fast lane:
Progressive prolongation of the PR interval culminating in a non-conducted P wave
PR interval is longest immediately before the dropped beat
PR interval is shortest immediately after the dropped beat
Heart Block:
Mobitz Type II (Hay AV block)
usually Irregular (may be regular)
Usually slow
Popping P waves
Not every P wave followed by QRS
PR interval constant when present
Sudden drop of QRS
Life in the fast lane:
Intermittent non-conducted P waves without progressive prolongation of the PR interval
PR interval in the conducted beats remains constant.
P waves ‘march through’ at a constant rate.
RR interval surrounding the dropped beat(s) is an exact multiple of the preceding RR interval (e.g. double the preceding RR interval for a single dropped beat, treble for two dropped beats, etc).
Heart Block:
AV block: 3rd degree CHB (complete heart block)
Regular ventricular rate (QRS)
Regular atrial rate (p)
NO RELATIONSHIP between P and QRS
Usually slow
P waves popping
QRS often wide in acute setting
Life in the fast lane:
In complete heart block, there is complete absence of AV conduction – none of the supraventricular impulses are conducted to the ventricles.
Perfusing rhythm is maintained by a junctional or ventricular escape rhythm. Alternatively, the patient may suffer ventricular standstill leading to syncope (if self-terminating) or sudden cardiac death (if prolonged).