ECG rhythms Flashcards
What is normal sinus rhythm defined by? (2)
P wave for each QRS and vice versa
PR interval
What is sinus arrythmia defined by?
Meets all criteria for sinus rhythm but rhythm itself is irregular because of changes due to respiration
ECG features of atrial fibrillation (2)
Disorganised atrial activity- absent P waves
Irregular QRS complexes
Cause of atrial flutter
Re-entry circuit within the atria resulting in an atrial rate of around 300bpm
ECG features of atrial flutter (2)
Sawtooth baseline best seen in V1 or II
Ventricular rate usually a division of 300 (e.g. 150, 100, 75)
Atrial flutter is a type of what?
Narrow complex tachycardia
What is junctional rhythm and how does it appear on ECG?
Electrical impulse begins in the AV node and travels retrograde. Results in inverted P waves after the QRS
What is supraventricular tachycardia?
Narrow complex tachy that originates above or involves the AV node
ECG features of SVT?
Regular narrow complex tachy. Often no clear P waves
How does the morphology of an atrial eptopic differ from a normal P wave?
Narrow and pointed (compared to broad and flat)
What are the defining features of ventricular rhythms? (2)
They are always broad complex and always pathological
What are ventricular complexes?
Heartbeat initiated by Purkinje fibres
What is a) bigeminy and b) trigeminy?
a) 1 sinus beat + one ventricular premature complex
b) 1 sinus beat + two VPCs
What is ventricular tachycardia?
Regular broad complex tachy
What can polymorphic VT (e.g. torsades de point) be confused with?
ventricular fibrillation
What are polymorphic VTs often associated with?
Long QT syndrome
What is a fusion beat?
When a normal beat fuses with a VT complex
What is a capture beat?
A normal QRS between abnormal beats
What are fusion beats and capture beats both “proof” of?
Independent rhythms in atria and ventricles
Why can it sometimes be difficult to distinguish ventricular rhythms from supraventricular rhythms + bundle branch block?
How can these be distinguished?
Both give you a broad QRS complex.
Good predictor of VT is pre-existing coronary disease. Capture and fusion beats are always VT
Good predictorof SVT is pre-existence of LBBB/RBBB
