ECG Flashcards
How many physical leads are there in a 12 lead ECG
10
List the names and anatomical placement of all the leads of a 12 lead ECG
V1 - Right sternal edge 4th intercostal space
V2 - left sternal edge 4th intercostal space
V3 - halfway between V2 and V4
V4 - 5th intercostal space mid clavicular line
V5- level with V4 anteriorly axillary line
V6 - 5th intercostal space mid axillary line
- Right arm = red
- Left arm = yellow
- Leg leg = green
- right leg = black
what speed is a normal ECG set at
25 mm/sec
How many large squares is 1 second
5
what amplitude is a normal ECG set at
10mm = 1mV
What do you need to consider when assessing whether an ECG is of adequate technical quality to assess
- labelled with name, date and age
- baseline - if this wanders a lot across the page then it may be difficult to interpret
- movement artefact - a sudden movement is easy enough, regular small movements like shivering or parkinsons may look like major abnormality
- electrical artefacts - pacemaker spike, mobile phone
- missing leads or wrong connected leads - easy to spot if you know the hex axial system and normal progression
what do absent P waves represent
- atrial fibrillation
What are the similarities and differences on appearance between sinus arrhythmia and AF
Similar
- both are irregularly irregular although there may be more of a pattern in sinus arrhythmia if they are breathing regularly and usually less variation in rate
Different
- every QRS has a P wave in SA, no relationship between p and QRS in AF
How do you measure the PR interval
from the start of the P wave to the Q wave
What is a normal PR interval and what does a prolonged PR interval represent
120-200msec
- if it is prolonged this represents heart block
what is the QT interval
below 400-440 messes
How do you measure the PR interval
from the start of the QRS complex
how broad is the QRS complex
120 mesec
what is the QT interval
Start of QRS to end of T wave
- corrected to rate
what is the relevance of QT interval
- QT interval represents electrical depolarisation and depolarisation of the ventricles
- A lengthened QT interval is a marker for the potential of ventricular tachyarrhtymias and a risk factor for sudden death
