ECG Fundamentals Flashcards
What is the regular axis of the QRS complex?
-30 -> +90 degrees
What is the J point on an ECG?
Transition point of QRS complex to ST segment
What do each of the main components of an ECG represent?
P Wave: Atrial Depolarisation
QRS Complex: Ventricular Depolarisation
T Wave: Ventricular Repolarisation
How long are each of the main ECG intervals meant to be?
PR: 120-200ms (Long shows heart block)
QT: 0.35-0.45s
(QRS Complex less than 110 ms)
Where would you place lead 1, 2 and 3 on the ECG?
1: RA -> LA w/ +ve electrode at LA (0deg)
2: RA -> LL w/ +ve at LL (60deg)
3: LA -> LL w/ +ve at LL (120deg)
Where would you place the av leads?
avF: 1/2 way between LA and RA to LL w/ +ve on LL (90deg)
avL: 1/2 way between RA and LL to LA w/ +ve on LA (-30deg)
avR: 1/2 way between LA and LL to RA w/ +ve RA (-150deg)
How many seconds do squares represent on ECG?
Small: 0.04s
Large: 0.2s
Which lead produces all negative waves?
avR
Which leads would produce QRS complex upright?
1 and 2
In which leads must the R and S waves grow?
R: Chest leads V1 to V4
S: Chest leads V1 to V3 (Disappear in V6)
In which leads will T waves and P waves be seen upright?
Leads 1, 2, V2-6
What abnormalities on P waves would be shown?
Tall pointed: Right atrial enlargement
M-shaped: Left atrial enlargement
What are 3 signs of abnormal T waves?
1) Symmetrical
2) Tall and peaked
3) Biphasic/Inverted
What does plateau phase of cardiac AP coincide with on ECG?
QT interval (QT decreases after HR increases)