Bradycardia

Last reviewed: 23 Aug 2023

Last updated: 06 Jan 2023

Sinus bradycardia is any heart rhythm slower than 50 bpm, even if transient, owing to sinus node dysfunction and/or atrioventricular (AV) conduction abnormalities.

Causes include intrinsic sinus node, AV nodal, and His-Purkinje disease, or extrinsic influences, which may be reversible.

Common symptoms include syncope, fatigue, and dizziness; however, the patient may be asymptomatic.

Evaluation involves determining the association of symptoms with heart rate and an assessment of underlying cardiovascular conditions. A 12-lead ECG and/or a heart monitor are the diagnostic tests of choice.

Patients with a reversible cause may not require long-term therapy; however, patients with nonreversible causes may require an implantable pacemaker with or without a defibrillator. Urgent treatment may include temporary pacing and drug interventions.

Potentially life-threatening complications, including cardiovascular collapse and death, may occur.

Definition

While some consider bradycardia to be a heart rate <60 bpm, this is in dispute and most consider rates of <50 bpm to represent bradycardia. A study of 500 healthy people, using ECG recordings, showed the mean afternoon heart rate to be 70 bpm in men and women, with two standard deviations being 46 to 93 bpm in men and 51 to 95 bpm in women.[1][2] A slow heart rate is common under various circumstances and does not necessarily require treatment unless it causes symptoms. Nonetheless, some patients, even if asymptomatic, may require interventions to prevent life-threatening complications. This topic focuses on electrical causes of bradycardia.

History and exam

Key diagnostic factors

pulse rate <50 bpm
age >70 years
use of known causative medications
presence of known underlying cause
dizziness/lightheadedness
syncope
fatigue
exercise intolerance
shortness of breath
cannon a-waves in jugular venous pulse
jugular venous distension

More key diagnostic factors

Other diagnostic factors

increased intracranial pressure
abnormal heart sounds
abdominal or lower extremity edema
hypotension
mental status changes
pallor
extremities cool to touch
hypothermia
chest pain
rashes
thyroid goiter

Other diagnostic factors

Risk factors

use of known causative medications
age >70 years
recent myocardial infarction
surgery
percutaneous valve replacement procedures
hypothyroidism
electrolyte disorders
acidosis
infections
exposure to toxins
hypothermia
infiltrative diseases
sleep-disordered breathing
epilepsy

More risk factors

Diagnostic investigations

1st investigations to order

12-lead ECG
Holter monitoring
event monitor/mobile cardiac telemetry
exercise testing
carotid sinus massage
echocardiogram
thyroid function tests
basic metabolic panel
arterial blood gas
cardiac biomarkers
serum digoxin level
serum creatinine

More 1st investigations to order

Investigations to consider

implantable-loop recorder
tilt-table testing
Lyme titers
electrophysiology testing
nocturnal pulse oximetry or overnight polysomnography

More investigations to consider

Treatment algorithm

ACUTE

hemodynamically unstable

hemodynamically stable: sinus node dysfunction

hemodynamically stable: acquired atrioventricular block

hemodynamically stable: congenital atrioventricular block

hemodynamically stable: vagally mediated bradycardia

hemodynamically stable: bradycardia associated with neurologic disorders

Contributors

Authors

Brian Olshansky, MD, FAHA, FACC, FHRS, FESC

Professor Emeritus

University of Iowa

Iowa City

Adjunct Professor

Des Moines University

Electrophysiologist

Covenant Hospital

Waterloo

VA Hospital

Iowa City

CGH Medical Center

Sterling

Disclosures

BO declares that he has no competing interests.

Sandeep Saha, MD, MS, FACC, FHRS

Cardiologist and Cardiac Electrophysiologist

Oregon Heart Center

Consultant, Cardiology and Cardiac Electrophysiology

Salem Health Hospitals and Clinics

Salem

Disclosures

SS is a consultant for Medtronic and St Jude Medical. He is on the speakers' bureau for Medtronic. None of these activities are relevant to the content of this topic.

Rakesh Gopinathannair, MD, MA, FAHA, FACC, FHRS

Director, Cardiac Electrophysiology Laboratories

Kansas City Heart Rhythm Institute and Research Foundation

EP Medical Director

Research Medical Center, HCA Midwest Health

Overland Park

Clinical Professor of Medicine

University of Missouri-Columbia

Columbia

Disclosures

RG is a consultant for St. Jude Medical, Biotrionik, and Boston Scientific. He is on the speakers' bureau for Pfizer Inc. and Zoll Medical. He serves as a physician advisor for HealthTrust PG and AltaThera Pharma, and PaceMate. None of these activities are relevant to the content of this topic.

Acknowledgements

Professor Brian Olshansky, Dr. Sandeep Saha, and Professor Rakesh Gopinathannair would like to gratefully acknowledge Dr Giselle Statz for her contributions to this version of the topic. They would also like to acknowledge Dr Renee M. Sullivan, Dr Weiwei Li, Dr Alexander Mazur, and Dr Chirag M. Sandesara, previous contributors to this topic.

Disclosures

GS, RMS, WL, AM, and CMS declare that they have no competing interests.

Peer reviewers

Nora Goldschlager, MD

Professor of Clinical Medicine

University of California

Chief

Clinical Cardiology

San Francisco General Hospital

Director

Coronary Care Unit

ECG Laboratory and Pacemaker Clinic

San Francisco

Disclosures

NG declares that she has no competing interests.

Paul Heidenreich, MD

Associate Professor of Medicine

Stanford University

Stanford

Disclosures

PH declares that he has no competing interests.

Juan M. Sztajzel, MD

Cardiology Center and Medical Polyclinics

University Hospital Geneva

Geneva

Switzerland

Disclosures

JMS declares that he has no competing interests.

Differentials
- Ventricular bigeminy
- Frequent premature ventricular contractions (PVCs)
- Atrial fibrillation
More Differentials
Guidelines
- 2021 ESC Guidelines on cardiac pacing and cardiac resynchronization therapy
- 2020 AHA Guidelines for cardiopulmonary resuscitation and emergency cardiovascular care
More Guidelines
Patient leaflets
Bradycardia
More Patient leaflets
Videos
How to perform an ECG: animated demonstration
More videos
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Bradycardia

Summary

Definition

History and exam

Key diagnostic factors

Other diagnostic factors

Risk factors

Diagnostic investigations

1st investigations to order

Investigations to consider

Treatment algorithm

hemodynamically unstable

hemodynamically stable: sinus node dysfunction

hemodynamically stable: acquired atrioventricular block

hemodynamically stable: congenital atrioventricular block

hemodynamically stable: vagally mediated bradycardia

hemodynamically stable: bradycardia associated with neurologic disorders

Contributors

Authors

Brian Olshansky, MD, FAHA, FACC, FHRS, FESC

Disclosures

Sandeep Saha, MD, MS, FACC, FHRS

Disclosures

Rakesh Gopinathannair, MD, MA, FAHA, FACC, FHRS

Disclosures

Acknowledgements

Disclosures

Peer reviewers

Nora Goldschlager, MD

Disclosures

Paul Heidenreich, MD

Disclosures

Juan M. Sztajzel, MD

Disclosures

Differentials

Guidelines

Patient leaflets

Videos

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