Electrical Conduction of the Heart Flashcards
What does one big square represent for Time and voltage on an ECG respectively?
Time= 0.2s
Voltage= 0.5mV
Describe phase 0 of Cardiac action potential
Sodium and Calcium channels open causing an influx of ions depolarising the myocyte
What happens at Phase 1 of Cardiac action potential?
Sodium channels close, meaning the membrane stops depolarising
What happens at Phase 2 of the Cardiac action potential? Why?
Potassium channels open causing sodium to flow into out of membrane
Calcium channels stay open to counter effect of Potassium and maintain the Plateau of Depolarisation
What happens during Phase 3 of cardiac action potential?
Ca2+ channels shut resulting in rapid repolarisation
What does a Bipolar lead measure ECG?
Measures the potential difference between two electrodes
What is a unipolar lead ECG?
Measures Potential difference between an electrode and a combined reference electrode
What is an electrode in an ECG? How many are needed for a 12 lead ECG?
Physical connection to patient to measure potential at point
10 electrodes needed for a 12 lead ECG
What is a Lead ECG? What are the 12 Leads in a 12 lead ECG?
Graphical representation of electrical activity in a particular ‘vector’
I-III
aVL
aVF
aVR
V1-6
What are the three Bipolar Limb leads? What do the they show?
I-III
Conduction between Potential difference between RA, LA and LL
What are the 4 Main Electrodes used in ECG? Which one is not used?
RA,LA,LL and RL
RL not used
Which of the 3 important electrodes are positive and which ones are negative?
RA-negative
LA and LL- positive
What are the three Unipolar leads formed as a result of the RA, LA and LL electrodes?
aVR
aVL
aVF
Which are the Septal Chest leads? What artery supplies this area?
V1, V2
Left anterior descending/ Right coronary artery
Which are the Lateral chest leads? Which artery supplies this area?
V5,V6
Circumflex artery
