intro to ECG

Question 1

what is an ECG?

Answer 1

• recording of potential changes

- detected by electrodes positioned on the body

Question 2

what is the purpose of an ECG?

Answer 2

provides info about cardiac rate, rhythm, chamber size, the electrical axis of the heart
- main test to assess for myocardial ischaemia and infarction

Question 3

what does electrical activity within and between cardiac muscle cells cause?

Answer 3

• current flow within the heart

- current flow within the surrounding tissue

Question 4

how does a vector come about within the cardiac system?

Answer 4

charges that are separated constitute an electrical dipole = vector that has magnitude and direction
- allows the electrical axis of the heart to be estimated

Question 5

how are the magnitude and direction calculated? (of a vector)

Answer 5

> magnitude- determined by the mass of cardiac muscle that is involved in the generation of the signal
direction - determined by the overall activity of the heart at any instant in time and varies during the cardiac cycle

Question 6

what is a rhythm strip?

Answer 6

• prolonged recording of one lead
• usually lead 2
  allows you to determine heart rate and identify the cardiac rhythm