ECG Flashcards
(46 cards)
What do leads refer to in an ECG
the view of the heart
Define cardiac vectors
reflect the magnitude and direction of electrical events in the heart, measured by electrocardiography
What does an isoelectric line suggest
Mo net change in voltage i.e. the vectors are perpendicular to the lead
What denotes the duration of an event in an ECG
width of deflection
What are upward deflections toward in an ECG
Cathode (+)
What are downward deflections toward in an ECG
Anode (-)
What does steepness of a line denote in an ECG
velocity of action potential
What occurs at P in an ECG
atrial depolarisation and contraction
What occurs through QRS in an ECG
ventricular depolarisation and contraction (+atrial depolarisation)
What occurs at T in an ECG
Ventricular repolarisation and relaxation
What occurs at Q in an ECG
Septal depolarisation in the bundle branches
What occurs at R in an ECG
Ventricular depolarisation in the Purkinje fibres
What occurs at S in an ECG
Late ventricular depolarisation in the Purkinje fibres
Which electrodes does lead I read from
right arm to left arm
Which electrodes does lead II read from
Left leg to right arm
Which electrodes does lead III read from
left arm to left leg
What is used to enhance conduction on the limb electrodes
Conductive gel
What planes are the leads visual representations of
Coronal and horizontal plane
Which leads have a fixed anode
Lead I, II, III
Which leads have a viral anode
aVR, aVL, aVF, V1-V6
Which lead is usually isoelectric
avL as it is viewed from bottom right to top left
Where are the chest leads placed
V1 - right 4th intercostal V2 - left 4th intercostal V3 - halfway V2 V4 V4 - 5th intercostal space mid-clavicular line V5 - V4 at the Anterior axillary line V6 - V4 at the mid-axillary line
Which lead is commonly used
Lead II
What does each big square represent in most ECGs
1mV
