Unit 6 - Cardiovascular - ECG 2 Flashcards
What is the relationship between voltage amplitude and the mass of tissue?
The voltage amplitude is directly related to the mass of tissue undergoing depolarisation or repolarisation
Which direction does the wave of depolarisation spread?
In many different directions simultaneously
What is the mean electrical vector?
The sum of all of the individual vectors at a given instant in time
What is the Einthoven triangle?
A triangle formed from the left arm, left leg and right arm where bipolar leads are placed for a 12 lead ECG
How many leads are there on an ECG?
Leads give different ‘pictures’ of electricity activity depending on their position relative to mean electrical vector
- there are 12 leads in total
Which is the most common lead used by clinicians to look at overall electrical activity of the heart?
Lead 2
- follows path of depolarisation
What are leads 1 - 3 referred to?
Limb leads
What are the 3 augmented leads?
aVL - left arm
aVR - right arm
aVF - left leg/foot
Where is the aVL lead placed?
-30 degrees relative to the lead I axis
Where is the aVR lead placed?
-150 degrees relative to the lead I axis
Where is the aVF lead placed?
+90 degrees relative to the lead I axis
How many leads are placed in the frontal plane?
6 leads
Where is the mean electrical axis?
Sum of all mean electrical vectors during ventricular depolarisation
- normally 40 degrees
What can axis deviations be caused by?
Increased cardiac mass - hypertrophy Changes in conduction pathway Infarcted regions being incapable of activation - scar tissue
What are the 6 chest leads?
Unipolar leads to assess activity in a plane perpendicular to the frontal plane V1 V2 V3 V4 V5 V6
