ECG interpretation basics Flashcards
(10 cards)
ECG interpretation basics
P Wave
a) What does the P wave represent?,
b) What is it’s normal length?
a) Atrial depolarisation,
b) <0.12s (3 small squares).
ECG interpretation basics
PR interval
a) What does the PR interval represent?,
b) Measured from,
c) Normal length,
d) Prolonged.
a) Atrial depolarisation complete,
b) Start of P wave to start of QRS,
c) B/W 0.12 and 0.20s.
d) A PR interval >0.20s indicates slower conduction b/w atria and ventricles and suggests 1st deg heart block.
ECG interpretation basics
QT interval
a) Represents,
b) Measured from,
c) What is it’s normal length?
a) Time taken for ventricular depolarisation and repolarization,
b) Start of the QRS complex to the end of the T wave,
c) B/W 0.36 and 0.44 s.
ECG interpretation basics
QRS Complex
a) What does the QRS Complex represent?,
b) Normal width,
c) Generally divided into 2 camps
a) Ventricular depolarization,
b) B/W 0.8 and 0.12s,
c) Narrow/Normal complex - Supraventricular origin
Wide complex - Ventricular origin or a block is
occurring.
ECG interpretation basics
PR Segment
a) Represents.
a) Electrical conduction passing through the AV node.
Allows atria to empty of blood prior to contraction of
ventricles.
ECG interpretation basics
ST Segment
a) What does the ST Segment represent?,
b) What shape should it be?
a) Completion of venricular depolarization and beginning
of ventricular repolarization.
b) This segment should be isoelectric (flat).
ECG interpretation basics
T Wave
a) What does the T wave represent?,
b) What shape should it be?
a) Ventricular repolarization,
b) Generally it is round and upright.
ECG interpretation basics
Ventricular Tachycardia (VT)
3 R’s
a) Rate - B/W 100 and 250bpm,
b) Regularity - Regular however can be monomorphic or
polymorphic.
c) Resemblance - Bizarre appearance.
Unable to ID P wave or T wave. Therefor unable to
assess PR interval or QT interval.
ECG interpretation basics
Explain the difference b/w monomorphic and polymorphic when it comes to resemblance.
Monomorphic presents the same (shape) throughout.
Polymorphic is NOT the same throughout (eg. Torades de Pointe).
ECG interpretation basics
QT interval
Interesting to note
* Relationship to HR,
* Men and Women.
QT interval is inversely proportional to HR.
ie. QT interval shortens at faster HR and lengthens at slower HR.
Men have shorter QT intervals than women.
