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Sinus Bradycardia Clinical Presentation

  • Author: Mark W Livingston, MD; Chief Editor: Erik D Schraga, MD  more...
Updated: Dec 18, 2014


Sinus bradycardia is most often asymptomatic. However, symptoms may include the following:

  • Dizziness
  • Lightheadedness
  • Chest pain
  • Shortness of breath
  • Exercise intolerance

Pertinent elements of the history include the following:

  • Previous cardiac history (eg, myocardial infarction, congestive heart failure, valvular failure)
  • Medications
  • Toxic exposures
  • Prior illnesses


Cardiac auscultation and palpation of peripheral pulses reveal a slow, regular heart rate.

The physical examination is generally nonspecific, although it may reveal the following signs:

  • Decreased level of consciousness
  • Cyanosis
  • Peripheral edema
  • Pulmonary vascular congestion
  • Dyspnea
  • Poor perfusion
  • Syncope


Causes of sinus bradycardia include the following:

  • One of the most common pathologic causes of symptomatic sinus bradycardia is the sick sinus syndrome.
  • The most common medications responsible include therapeutic and supratherapeutic doses of digitalis glycosides, beta-blockers, and calcium channel-blocking agents.
  • Other cardiac drugs less commonly implicated include class I antiarrhythmic agents and amiodarone.
  • A broad variety of other drugs and toxins have been reported to cause bradycardia, including lithium, paclitaxel, toluene, dimethyl sulfoxide (DMSO), topical ophthalmic acetylcholine, fentanyl, alfentanil, sufentanil, reserpine, and clonidine.
  • Sinus bradycardia may be seen in hypothermia, hypoglycemia, and sleep apnea.
  • Less commonly, the sinus node may be affected as a result of diphtheria, rheumatic fever, or viral myocarditis.
Contributor Information and Disclosures

Mark W Livingston, MD Consulting Staff, Department of Emergency Medicine, Yakima Valley Memorial Hospital

Disclosure: Nothing to disclose.


David T Overton, MD, MBA Professor and Chairman, Department of Emergency Medicine, Associate Dean for Educational Affairs, Western Michigan University School of Medicine

David T Overton, MD, MBA is a member of the following medical societies: American College of Emergency Physicians, Society for Academic Emergency Medicine, Michigan College of Emergency Physicians, Association of Academic Chairs of Emergency Medicine, American College of Physicians

Disclosure: Nothing to disclose.

Specialty Editor Board

Francisco Talavera, PharmD, PhD Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Received salary from Medscape for employment. for: Medscape.

Gary Setnik, MD Chair, Department of Emergency Medicine, Mount Auburn Hospital; Assistant Professor, Department of Emergency Medicine, Harvard Medical School

Gary Setnik, MD is a member of the following medical societies: American College of Emergency Physicians, Society for Academic Emergency Medicine, National Association of EMS Physicians

Disclosure: Medical Director for: SironaHealth.

Chief Editor

Erik D Schraga, MD Staff Physician, Department of Emergency Medicine, Mills-Peninsula Emergency Medical Associates

Disclosure: Nothing to disclose.

Additional Contributors

Daniel J Dire, MD, FACEP, FAAP, FAAEM Clinical Professor, Department of Emergency Medicine, University of Texas Medical School at Houston; Clinical Professor, Department of Pediatrics, University of Texas Health Sciences Center San Antonio

Daniel J Dire, MD, FACEP, FAAP, FAAEM is a member of the following medical societies: American Academy of Clinical Toxicology, American Academy of Pediatrics, American Academy of Emergency Medicine, American College of Emergency Physicians, Association of Military Surgeons of the US

Disclosure: Nothing to disclose.

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