Electrocardiography Flashcards
state 3 things that ECGs are of great value in diagnosing
MI, arrhythmia and ventricular hypertrophy
The electrical activity of the heart extends through the body tissue and can be recorded using up to ___ leads (electrodes) placed on the surface of the body.
12
The ECG is a summation of all the heart’s ______ activitites
electrical
what is the P wave caused by?
atrial defibrillation
Which wave is this describing?
Its contour is usually smooth, positive and of uniform size. Its duration is normally less than 0.12 seconds.
P wave
What does the QRS complex represent?
depolarisation of the ventricles
The T wave is due to _____ _____ and is usually negative/positive
ventricular repolarisation
positive
What name is given to the portion of the ECG wave from the beginning of the P wave to the beginning of the QRS complex? (its duration is normally 0.12 - 0.2 seconds)
the PR interval
Where does the QT interval extend from and to?
What does this period of time represent?
From the onset of the QRS complex to the end of the T wave.
It represents the time between the start of ventricular depolarization and the end of ventricular repolarization.
True or false - The QT interval is dependent upon heart rate. It varies inversely with heart rate.
True (i.e. heart rate increases, QT interval becomes shorter and vice versa )
What does the ST segment represent?
The period from the end of ventricular depolarization to the beginning of ventricular repolarization.
