Serial ECG
PR prolongation (varying degrees of AV block)
AV block occurs more commonly with verapamil
Bradyarrhythmia
Less common presentations include ventricular dysrhythmias and QRS widening, which are more commonly seen in toxicity of membrane-stabilizing beta-blockers (i.e. propranolol)
Glucose
hyperglycemia, may help distinguish β-blocker toxicity
Chemistry
Serum<unk>  is often normal
It is the effect on intracellular<unk>  in the myocardium and smooth muscle that leads to the toxicity of CCBs
Continuous cardiac monitoring
PR prolongation (varying degrees of AV block)
AV block occurs more commonly with verapamil
Bradyarrhythmia
Less common presentations include ventricular dysrhythmias and QRS widening, which are more commonly seen in toxicity of membrane-stabilizing beta-blockers (i.e. propranolol)
AV block occurs more commonly with verapamil
hyperglycemia, may help distinguish β-blocker toxicity
Serum<unk>  is often normal
It is the effect on intracellular<unk>  in the myocardium and smooth muscle that leads to the toxicity of CCBs
Calcium channel blocker toxicity
Cardiac
Tricyclic antidepressant toxicity
Inferior MI 
Clonidine toxicity
Sick sinus syndrome
Beta-blocker toxicity
Neurocardiogenic/reflex-mediated