Sinus bradycardia 2166438 215611025 2008-05-28T23:08:28Z Arcadian 104523 nav {{SignSymptom infobox | Name = Sinus bradycardia | ICD10 = | ICD9 = {{ICD9|427.81}} | MeshID = D001146 | }} '''Sinus [[bradycardia]]''' is a heart rhythm that originates from the sinus node and has a rate of under 60bpm. ==Etiology== *This rhythm may be caused by one of the following: **Increased [[vagal]] tone. **Intrinsic disease of the [[SA node]]. **An effect of [[drugs]], such as the use of [[digitalis]], [[beta-blockers]], or quinidine. **[[Sleep]] **It could also be a normal finding in a healthy, well-conditioned person. ==ECG Characteristics== *Rate: Less than 60. *Rhythm: Regular. *P waves: Upright, consistent, and normal in morphology and duration. *P-R Interval: Between 0.12-0.20 seconds in duration. *QRS Complex: Less than 0.12 seconds in width, and consistent in morphology. ==Significance== The decreased heart rate can cause a decreased cardiac output resulting in symptoms such as lightheadedness, dizziness, hypotension, vertigo, and syncope. The slow heart rate may also lead to atrial, junctional, or ventricular ectopic rhythms. Sinus bradycardia is not necessarily a bad symptom. People who regularly practice sports may have sinus bradycardia, because their trained hearts can pump enough blood in each contraction. == See also == *[[Sinus tachycardia]] *[[Long QT syndrome]] {{Heart diseases}} [[Category:Cardiac electrophysiology]] [[nl:Sinusbradycardie]] [[sv:Sinusbradykardi]]