The ECG changes associated with WPW syndrome include

• Shortened PR interval (less than 0.12 sec). 

• A delta "slur" wave 

• A broad QRS interval (greater than 0.10 sec).

Long QT interval

To measure the corrected QT interval  (QTc)

QTc= QT measured / square root of the RR interval

The "normal" QTc is less than 0.44 but that the distribution of QTc in the normal population overlaps with the distribution of the QTc in those with LQT.

Other factors like T-wave morhology need to be considered and in about 10% of cases the diagnosis can be difficult to make.

If suspicious further testing such exercise testing or Holter monitoring  is often helpful.

 If there is any reason to suspect long QT syndrome, then discuss with Cardiologist on call.

Hypokalaemia an hyperkalaemia

Hypokalaemia: flattened or inverted T waves, ST depression, PR prolongation.

Hyperkalaemia: peaked T waves, widened QRS.