Department of Physiology1
Basic algorithm:
How to evaluate a normal ECG record
Compendium of Physiology
Autumn 2019
Tibor Stračina
Department of Physiology2
A 12-lead ECG record
Patient‘s name; date and
time of measurement
Time and voltage scale
Bipolar limb leads (I, II, III)
Unipolar augmented limb
leads (aVR, aVL, aVF)
Lead II in long time scale
Values from automatic
analysis (TF – heart rate)
Unipolar chest leads
(V1 – V6)
Calibration mark
Department of Physiology3
The shape of the standard ECG curve:
waves, peaks, segments, and intervals
Pwave
PQsegment
QRScomplex
STsegment
Twave
PQinterval
QTinterval
RRinterval
R – the first positive
deflection of the
ventricular complex
S – a negative
deflection after the „R“
Q – a negative deflection
before the „R“
NOTE: In this lead, Q is not
present in the QRS complex
The level of the isoline
A negative
deflection
A positive
deflection
Department of Physiology4
Basic algorithm
1. Heart rhythm (regular/irregular; sinus/junctional/ventricular/other)
2. Heart rate (a value in bpm)
3. The duration of the P wave, the PQ interval, the QRS complex,
and the QT interval (in ms)
4. Position of ST segment (in isoline/elevated/depressed)
5. Transitional zone (position; lead V1 – V6)
6. Electric axis of the heart (position in degrees)