ECG Flashcards
What does the P wave show in an ECG
Atrial contraction
What does the QRS complex show in an ECG
Ventricular depolarisation
repolarisation of atria - but this is hidden because of the stronger QRS wave
What does the T wave show in an ECG
Ventricular repolarisation
How to identify right axis deviation in an ECG
Lead I is negative
Lead II is positive
Lead III is most positive
How to identify left axis deviation in an ECG
Lead I is positive
Lead II is negative
Lead III is negative
Causes of right axis deviation
not so important
PE
atrial septal defect
Ventricular septal defect
What is indicated when the P wave is peaked
Could be hypertrophy of right atrium
Causes of right atrium hypertrophy
Tricuspid valve stenosis
Pulmonary Hypertension
What is indicated when the P wave is broad or bifid
Left atrial hypertrophy
causes of Left atrial hypertrophy
Mitral stenosis
When is a QRS complex abnormal
When it is wider than 3 small boxes (120ms)
When the S wave is greater than the R wave in V1
When is a QRS wide
If there is a bundle branch block
Wolff-Parkinso -White syndrome
Abnormalities of the ST segment
If elevated - MI or pericarditis
Can be depressed - ischaemia, exercise induced angina, treatment with digoxin
What can you tell from the leads that have ST elevation
The location of the infarction
which leads represent inferior of the heart
II
III
aVF
which leads represent Lateral of the heart
I
aVL
V5
V6
which leads represent Anterior of the heart
V3
V4
which leads represent Septal of the heart
V1
V2
When you are looking at the P waves what are you asking yourself?
Are the P waves present
Do they occur regularly
Do they precede each QRS comlex (Sinus rythm)
Are they long, wide, or bifid
What can a prolonged PR interval mean
Heart block
What can a Shortened PR interval mean
Wolf Parkinson White syndrome.
Tell me about the PR interval
from the start of the P-wave to the start of the Q wave
3-5 small squares (200ms)
Are they consistent or changing?
Tell me about the ST segment
Starts at end of S wave and ends at start of T wave
Basically it is a flat line
Tell me about the T waves
T waves represent Ventricular repolarisation
Can be inverted or Tall
