7 ECG Abnormalities Flashcards
List sites a abnormal supra-ventricular rhythms may arise
- Sinus node
- Atrium
- AV node
How are supra-ventricular rhythms conducted into the ventricles?
His-Purkinje system
What are QRS complexes like in supra-ventricular rhythms?
Narrow
In ventricular rhythms what are the QRS complexes like?
Larger than 3 small boxes
What is sinus bradycardia and tachycardia?
B = below 60 T = Above 100
What is the most common cardiac arrhythmia?
Atrial fibrillation
In AF where are electrical impulses initiated from?
Different sites in the atrium called ectopic sites
How does AF present on an ECG?
- Absent P waves
- Wavy baseline
- Narrow QRS complex
- Irregularly irregular
What are the most common complications of atrial fibrillation?
Blood clots arising in the atria
What is heart block?
Block in the electrical conducting system between the atria and the ventricles
What are common causes of heart block?
Acute myocardial infacrtion
What is 1st degree AV heart block?
Prolonged PR interval, but every P wave is still followed by a QRS complex
PR interval is bigger than 1 PR square
What is 2nd degree AV heart block?
Atria are contracting normally but not every impulse from the atria is making it through to the ventricles
What is Mobitz type 1?
progressive PR lengthening until one P wave is not conducted
What is Mobitz type 2?
The PR interval is normal, but then get a sudden non conduction of a beat
What is 3rd degree heart block?
Atria are doing there thing but impulse is not getting through, no relationship between the p wave and the QRS complexes
What is a ventricular ectopic beat?
Causes ventricular contraction before the underlying rhythm would normally depolarise the ventricles
Get a wider and different shaped QRS complex compared to the usual
What is ventricular tachycardia?
Get a consecutive run of more than 3 ectopic beats
In terms of cardiac output describe atrial fibrillation and ventricular fibrillation?
Cardiac output present in AF, no cardiac output or heart beat is present in VF
Which part of the heart is most vulnerable to ischemia?
Sub endocardial muscle
How is ischaemia identified on a ECG?
ST segment depression or T wave inversion
How is myocardial infarction identified on an ECG?
ST elevation
What is a pathological q wave a sign of?
A previous myocardial infraction
Describe a pathological Q wave?
More than 1 small square wide or 2 small square deep, the depth is more than 1/4 of the height of subsequent R wave and is greater than 1/3 the amplitude of the QRS complex
How can identify hyperkalameia on a ECG?
Tall T wave
How can identify hypokalaemia?
Low T wave
What is the cardiac axis?
The average (overall) direction of spread of the ventricular depolarisation
What is left axis deviation?
When overall direction ventricular depolarisation is upwards and to the left
What is right axis deviation?
When overall direction ventricular depolarisation is downwards and to the right
What is often the earliest ECG change seen during myocardial infarction?
Tall peaked T waves
How do you tell if the cardiac axis is normal?
In normal cardiac axis Lead II has the most positive deflection compared to Leads I and III
What does a prolonged PR interval suggest?
An atriventricular delay
