ECG Analysis Flashcards
What is a normal heart rate?
60-100bpm
How long is a normal p-wave?
Less than 80ms
How long is a normal PR interval?
Less than 200ms
How long is a normal QRS complex?
Less than 120ms
How do you calculate the heart rate from an ECG?
Determined from R-R intervals; count the R waves in 30 squares then multiply by 10 (1 sq=0.2s)
What time period does each square on an ECG represent?
0.2 seconds
What is a regularly irregular heart rhythm?
Where there is a regular abnormality of the ECG
What is an irregularly regular heart rhythm?
When the RR intervals vary but the ECG itself is normal
What is an irregularly irregular heart rhythm?
Where there is no order to the ECG whatsoever, and this can be indicative of heart failure
What is a normal PR interval?
120-200ms
What may a prolonged PR interval represent?
Heart block
What may a prolonged QRS complex present?
Abnormality of ventricular contraction or conduction
What may an elevated ST segment represent?
Myocardial infarction (STEMI)
What may a depressed ST segment represent?
Ischaemia - angina
What is another phrase for a normal ECG?
Normal sinus rhythm
How would sinus bradycardia appear on ECG?
All normal characteristics except a longer R-R interval, with HR less than 60bpm
How would sinus tachycardia appear on ECG?
All normal characteristics except a shorter R-R interval, with HR greater than 100bpm
How would ventricular tachycardia appear on ECG?
> Increased heart rate (tachycardia)
Prolonged QRS complex (due to abnormal ventricular conduction and contraction)
Unidentifiable p-waves as they are masked by the consistent ventricular depolarisation
What is the cause of ventricular tachycardia?
Abnormal tissues in the ventricles, aside from the AVN begin to generate a rapid and irregular heart rhythm
How would ventricular fibrillation appear on ECG?
There are no identifiable features on the ECG it becomes a mixture of uncoordinated wiggly lines
What is the cause of ventricular fibrillation?
Results from disorganised electrical signals which cause the ventricles to quiver instead of contract in a rhythmic fashion
How would first degree heart block appear on ECG?
The PR interval will be consistently prolonged (greater than 200ms)
What are the types of second degree heart block?
Type 1 - wenkenback (progressively longer PR interval until failure of QRS)
Type 2 - Mobitz II (normal PR interval until failure, then restarts)
How would second degree type I heart block appear on ECG?
Variable PR interval:
PR intervals will become progressively longer until a p-wave fails to produce a QRS complex, then the cycle starts again.