Editing Bradycardia (section)

==== Sinus bradycardia ====
[[Sinus bradycardia]] is a [[sinus rhythm]] of less than 50 BPM.<ref name="KusumotoSchoenfeldBarrett2019" /> Cardiac action potentials are generated from the SA node and propagated through an otherwise normal conduction system, but they occur at a slow rate. It is a common condition found in both healthy individuals and those considered well-conditioned athletes.<ref name="hafeez222" /> Studies have found that 50–85% of conditioned athletes have benign sinus bradycardia, as compared to 23% of the general population studied.<ref>{{Cite journal |vauthors=Bryan G, Ward A, Rippe JM |date=April 1992 |title=Athletic heart syndrome |journal=Clinics in Sports Medicine |publisher=Elsevier |volume=11 |issue=2 |pages=259–272 |doi=10.1016/S0278-5919(20)30529-9 |pmid=1591784}}</ref> The heart muscle of athletes has a higher [[stroke volume]], requiring fewer contractions to circulate the same volume of blood.<ref name="HN3">{{Cite book |title=Harwood-Nuss' Clinical Practice of Emergency Medicine |publisher=Lippincott Williams & Wilkins |year=2005 |isbn=978-0-7817-5125-4 |editor-last=Allan B. Wolfson |edition=4th |page=260}}</ref> Asymptomatic sinus bradycardia decreases in prevalence with age.{{cn|date=May 2025}}