ECG's Flashcards
What drug causes a prolongation of the QT interval?
First generation anti-psychotics
How do you work out the rhythm? (bpm)
Count the number of large squares within one R-R interval and divide 300 by this number E.g 300/4 = 75bpm
How do you calculate the heart rhythm if the R-R interval is irregular?
Count the number of complexes on the rhythm strip and multiply this by 6
e.g 10x 6 = 60bpm
What is meant by cardiac axis?
The overall direction of electrical spread within the heart
What is the normal PR interval duration?
120-200ms (3-5 small squares)
What would be considered a prolonged PR interval? and what does this suggest?
A PR interval >0.2 seconds. This indicates a atrioventricular delay.
Describe the types of heart block?
Type 1 - fixed prolonged PR interval (occurs between the SA and AV node)
Second degree (type 1) - progressive prolonging of the PR interval (Occurs IN the AV node)
Second degree (type 2) - consistent PR interval duration with intermittently dropped QRS complexes. (Occurs AFTER the AV node in the bundle of his or purkinjie fibres)
Third degree - complete heart block. No association between P waves and QRS complexes (occurs at or after the AV node)
What is a Q wave and when would you be concerned?
If isolated it is okay but if you notice it in whole territories then it may suggest a previous MI
What might ST depression in two consecutive leads indicate?
Cardiac ischaemia
What is considered tall tented T waves?
- if it is >5mm in the limb lead (I, II, III, aVF, aVL and aVR)
- & >10mm in the chest lead (V1- V6)
What is the J point ?
The point where the S wave joins the ST segment
What is meant by a flat T wave?
This is a non specific finding and can indicate ischaemia or electrolyte imbalance
How to calculate PR interval?
One small box is 0.04 secs
Calculating QT/QTc interval?
