ECG
PR prolongation
Bradycardia
QT Prolongation with sotalol
Wide QRS with propanolol
Any bradydysrhythmia
Obtain multiple ECGs over time to monitor any changes
Glucose
Chemistry
Creatinine (esp with atenolol)
Continuous cardiac monitoring
Respiratory rate
Propranolol can induce central apnea
PR prolongation
Bradycardia
QT Prolongation with sotalol
Wide QRS with propanolol
Any bradydysrhythmia
Obtain multiple ECGs over time to monitor any changes
Creatinine (esp with atenolol)
Propranolol can induce central apnea
Beta-blocker toxicity
Cardiac
Clonidine toxicity
Inferior MI 
Digoxin toxicity
Sick sinus syndrome
Calcium channel blocker toxicity
Neurocardiogenic/reflex-mediated