Practical points Flashcards
(42 cards)
how long should the p wave (atrial depolarisation) normally take?
0.08-0.12 seconds
how long should the p wave (atrial depolarisation) normally take?
0.08-0.12 seconds
how long should the QRS complex (ventricular depolarisation) normally take?
why does the T wave have an upward deflection?
the repolarisation - which would normally be negative is moving in a direction opposite to that of the depolarisation
Depolarization moving _____ the recording (+ve) electrode gives an upward deflection on the ECG, whereas ____ from causes a downward deflection
Depolarization moving towards the recording (+ve) electrode gives an upward deflection on the ECG, whereas away from causes a downward deflection
what does the T wave represent?
ventricular repolarisation
why is aVR inverted?
because the predominant vector is depolarisation moving away from the electrode
why does aVL and lead III have poorly resolved P and T waves?
the predominant vector is approximately perpendicular to the lead axis
why does lead II have a well resolved P and T wave?
the vector is approximately parallel to the lead axis
how long should the PR interval be?
(0.12- 0.2 seconds
what does the PR interval represent?
largely AV nodal delay
how do you work out the HR if it is irregular?
COUNT THE NUMBER OF QRS COMPLEXES IN 30 LARGE SQUARES, AND MULTIPLY BY 10
ST elevation in which leads indicates inferior infarct?
II,III,aVF
ST elevation in which leads indicates Lateral infarct?
I, aVL, V5/6
ST elevation in which leads indicates anterior infarct?
V3 and V4
ST elevation in which leads indicates Septal infarct?
V1 ans V2
which two leads indicate axis?
I and avF
if leads I and aVF are both positive, axis is…
normal
if leads I and aVF are both negative, axis is…
extreme RAD or extreme LAD
if lead I is positive but aVF is negative, axis is…..
LAD
if Lead I is negative but aVF is positive, axis is…..
RAD
what are the 5 steps in ECG interpretation
Verify patient details: name and date of birth
Check date and time in which the ECG was taken
Check the calibration of the ECG paper
Look at the rhythm strip
Look at individual leads for voltage criteria changes OR any ST or T-wave changes
how long should the QRS complex (ventricular depolarisation) normally take?
why does the T wave have an upward deflection?
the repolarisation - which would normally be negative is moving in a direction opposite to that of the depolarisation
