Electrolytes Disturbances and the ECG

 

Morphologic changes Arrhythmias
P wave PR Interval QRS duration ST segment T wave QT interval Other Slow Fast
K     depressed Flat/inverted   U wave 1o/2o AV block
 
Asystole
AF
PVCs
VF
K / 0     Peaked   Sine wave 2o/3o AV block
Asystole
Broad complex tachycardia
VF
Ca            Sinus Bradycardia  
Ca     depressed/
short
wide   2o/3o AV block
Asystole
 
Mg   depressed/
short
flat/wide/
inverted
U wave   AF
MAT
SVT
PVCs
VT
Torsade
VF
Mg            3o AV block
Asystole
(diastolic arrest)
 
Li   flat flat     Sinus/Bradycardic arrest (rare)