Abnormal ECG Flashcards
Rhythm arising from the SA node, Atrium or AV node are called…
Supraventricular rhythm
How are the Supraventricular rhythms conducted and what is the consequence on ventricular depolarisation?
- By His-Purkinje system
- Normalventricular depolarisation ,normal narrow QRS
Where do ventricular rhythms arise from and how do they spread ?
What do QRS look like ?
- From different foci in ventricle
- DONT spread via His-Purkinje system
- Wide QRS (>3 small boxes)
What do atrial beats look like on ECG ?
- Small p wave
- Normal QRS
What can you see on a AV junctional beat ECG ?
Reversed p wave because atrial depolarisation goes away from apex (AV to SA)
Normal QRS
Which lead is the best to look at p waves ?
II
What is normal sinus rhythm ?
- HR 60-100 bpm
- Regular
- p wave befor each QRS
- PR 0,12-0,20 s
- QRS < 0,12 s (3 small boxes)
Sinus rhythm with rate < 60bpm is called …
Bradycardia
What causes Atrial Fibrillation ?
Multiple atrial foci , chaotic impulses
What are the consequences of AF on the P wave , impulse and QRS ?
- No p wave , wavy baseline
- Impulses arrive at AV node at rapid irregular rate
- QRS normal but irregular
In AF, are all impulses arriving at the AV node conducted ? Why
No,
only some at irregular intervals because AV node in refractory period
How is the pulse and HR in AF ?
Irregularly irregular
What is Heart block ?
AV conduction blocks
-Delay or failure of impulse conduction from atrium to ventricle via AV node and bundle of HIS
What can cause heart block ?
Acute MI
Degenerative changes
What are the 3 types of heart block ?
- First degree
- 2nd degree
- -type 1 : Wenkenbach
- -type 2
- 3rd degree , Complete heart block
Describe ECG for First degree heart block
- P wave normal
- Prolonged PR interval (>5 small squares)
- QRS normal
Describe ECG for 2nd degree heart block TYPE 1
- Progressive lengthening of PR interval
- Until one P not conducted (Missing QRS)
- Then new cycle of lengthening (can be 2:1 …)
What happens on an ECG showing 2nd degree TYPE 2 heart block?
-Normal PR interval
-Sudden non-conduction of beat : Dropped QRS
(Skipped ventricular beat)
What happens in Complete heart block ? (Atrial Depolarisation, ventricle, impulse,HR)
- Normal atrial depolarisation
- Impulse not conducted to ventricles
- Ventricle pacemaker takes over : Ventricular Escape rhythm
- HR slow , poor BP
What does the ECG look like if Complete heart block ?
- P wave normal
- P-P interval constant
- QRS interval wide
- R-R intervals constant but slow (37bpm)
- No relationship between p and QRS
What causes an single abnormal wide QRS complex in ECG and why is it wide ?
- Ventricular ectopic beat du to ectopic focus in ventricular muscle
- QRS wide because slow because not spread through His-Purkinje system
How is Ventricular ectopic beat different from Ecape rhythm in 3rd degree heart block?
Wide QRS complex not regular.
Define Ventricular tachycardia
Run of more than 3 consecutive ventricular ectopic beats (broad complex tachycardia )
What is ventricular fibrillation ? What is the cause ?
- Abnormal , chaotic , fast ventricular depolarisation
- Due to impulses from numerous ventricular ectopic foci
