ECG 1 Flashcards
What will a wave of depolarisation approaching the positive electrode cause?
An upward blip
What will a wave of depolarisation approaching the negative electrode cause?
A downward blip
What is transmitted better - fast or slow events?
Fast events
STUDY THE DIAGRAM
What causes the P wave?
Wave of depolarisation towards the left leg
What is the PR interval?
The time between atrial depolarisation and ventricular depolarisation
What is shown by the QRS complex?
Time for whole ventricle to depolarise
What is shown by the QT interval?
The length of time the ventricles stay in the plateau phase before they are repolarised
What is the Q of the the QRS complex?
The intraventricular septum depolarising left to right
What is the R of the QRS complex?
The bulk of the ventricle depolarising from endocardium to epicardium
What is the S of the QRS complex?
The upper part of the interventricular septum depolarising
Which numbers on the diagram correspond to the Q, R and S of the QRS complex?
1 - Q
2 - R
3 - S
Why is the T wave positive?
The wave of repolarisation travels back up the heart
Why does the wave of depolarisation that causes the T wave travel back up the heart?
Epicardium is repolarised a lot faster than endocardium
When can the axis of the heart be altered?
- Heart rotation
- Hypertrophy of the heart wall
What will a changed heart axis result in?
Different readings on the standard limb leads
What are the 3 augmented limb leads?
- aVR
- aVL
- aVF
What is the orientation of aVR?
- Right arm positive relative to left arm and left leg
What is the orientation of aVL?
Left arm is positive compared to right arm and right leg
What is the orientation of aVF?
Right foot is positive but it is in the shape of a crucifix
STUDY THE AUGMENTED LIMB LEAD ECG TRACE
How are the precordial leads arranged?
In front of the heart
What anatomical plane is the heart analysed in by the precordial leads?
Transverse plane
Since the precordial leads are arranged from V1 (on the right side of the chest) to V6 (on the left side in the mid axillary line) what will the change in signal be?
V1 = negative
V6 = positive
Gradual change through V2 - V5 from negative to positive
What is the gradual change in signal type shown by the precordial leads called?
Progression
STUDY THE PRECORDIAL LEADS ECG TRACE
What is shown by the rhythm strip?
- Heart rate
- Allows you to measure the R-R wave interval
- Tells you if the QRS is preceded by a P wave
HIT ME WITH YA RHYTHM STRIP
What will the rhythm strip tell you about the PR interval?
If it is the correct length of time
What will the rhythm strip tell you about the QRS complex?
If it is too wide
What will the rhythm strip tell you about the QT interval
If it is too long
What does STEMI stand for?
ST Elevated Myocardial Infarction
What does the extend of STEMI indicate?
The severity of a heart attack
What is more serious - a MI with STEMI or a MI without STEMI?
MI with STEMI
