<unk>  is a heart rhythm that originates from the sinus node and has a rate of under 60 beats per minute. Common causes include sick sinus syndrome and pharmacotherapy such as beta-blockers.<unk>  is fairly common in highly trained athletes.  It only requires treatment if the patient is symptomatic.
Sinus bradycardia
Wide complex tachycardia
Sinus arrhythmia
Junctional tachycardia
Supraventricular arrhythmias
Narrow complex tachycardia
Sinus tachycardia
Inappropriate sinus tachycardia