This is simple and straightforward. Look for PR intervals and QT intervals.
A prolonged PR interval on its own is not a major issue. It represents a first degree block. However if combined with a left anterior fascicular block and a RBBB, it is a triphasicular block and the patient requires a pacemaker.
The QT Interval is very important.
It is usually given on the ECG, but can be calculated also. A clue as to a prolonged QT occurs when the end of the T wave is past the midpoint between the R-R Interval.
The QT Interval is measured from the beginning of QRS to end of T wave.
It can be calculated by QTc = QT/sq root of RR
>0.44 seconds concerning
Causes of Prolonged QT
Inherited Lange-Neilsen (AR), Romano-Ward(AD)
Drugs – amiodarone, sotalol, haloperidol, methadone
Other – Hypothyroidism, Hypercalcaemia