# Sinus Bradycardia --- **Sinus bradycardia** is a [[arrhythmia]] where the heart is beating too slowly, typically defined as <60 BPM, although it varies on the individual—very fit or athletic people have resting heartrates in the 30s and 40s. It is also common for people to have bradycardia when their metabolic needs are very low, such as when sleeping. This is why it is important to look for symptoms of low [[cardiac output]]/decreased perfusion as well as actual pulse rate. ## Causes - lower metabolic needs - i.e. sleeping - fit people - the heart is really really efficient - vagal stimulation - the [[vagus nerve]] is part of the [[parasympathetic nervous system]] and stimulation of it can slows the heartrate - vomiting can cause it - bearing down - This is actually how Elvis died (on the toilet!) - medications - MI/HF/CAD - can be idiopathic ![[sinus bradycardia.png]] >[!abstract]- Normal sinus rhythm for reference >![[normal sinus.png]] ## Signs & Symptoms The signs and symptoms of sinus bradycardia are those of low cardiac output or decreased perfusion: - lightheadedness/dizziness - especially with exertion - fatigue - syncope - dyspnea - chest pain/discomfort - confusion ## Treatment - O2 - telemetry - Sometimes IV fluids - careful with HF patients - [[atropine]] - an *anticholinergic* which stops the parasympathetic signals, speeding up the heart, used for bradycardia - can increase heart rate - monitor for tachycardia - acts to block muscarinic receptors (i.e. part of the parasympathetic) - pacing (if atropine doesn't work) - typically with a temporary pacemaker (i.e. transcutaneous pacing) ___