恶俗老狼 is absolutely correct:

This is symtompatic bradycardia manifested by Mobitz type 1 or Wenckebach.  If he does not have a pacemaker, anytime he could drop dead (sorry to say that).  For Mobitz type 2 and type 3 block, regardless of symptom or not, he will need a pacemaker.  Common causes will be CAD.  Electrolytes will be potassium, calcium, magnesium and etc.  But electrolytes problem happen in more of acute or subacute condition.

 

See cardiologist and get it done, asap.  It is usually a same day surgery done by interventional cardiologist and an anesthesiologist is usually at the table side.