Beta-blockers may slow the heart rate to a dangerous level if prescribed with calcium channel blocker-type medications. Bradycardia is also part of the mammalian diving reflex. Diagnosis
A diagnosis of bradycardia in adults is based on a heart rate less than 60 BPM, although some studies use a heart rate of less than 50 BPM. This is determined usually either by palpation or ECG. If symptoms occur, a determination of electrolytes may be helpful in determining the underlying cause. Management
The treatment of bradycardia is dependent on whether or not the person is stable or unstable. Stable
Emergency treatment is not needed if the person is asymptomatic or minimally symptomatic. Unstable
If a person is unstable, the initial recommended treatment is intravenous atropine. Doses less than 0.5 mg should not be used, as this may further decrease the rate. If this is not effective, intravenous inotrope infusion (dopamine, epinephrine) or transcutaneous pacing should be used. Transvenous pacing may be required if the cause of the bradycardia is not rapidly reversible.In children, giving oxygen, supporting their breathing, and chest compressions are recommended. Epidemiology
In clinical practice, elderly people over age 65 and young athletes of both sexes may have sinus bradycardia. The US Centers for Disease Control and Prevention reported in 2011 that 15.2% of adult males and 6.9% of adult females had clinically-defined bradycardia (a resting pulse rate below 60 BPM). Society and culture
Records
Daniel Green holds the world record for the slowest heartbeat in a healthy human, with a heart rate measured in 2014 of 26 BPM.
Impulses originating within or below the bundle of His in the AV node will produce a wide QRS complex with heart rates between 20 and 40 BPM. Those above the bundle of His, also known as junctional, will typically range between 40 and 60 BPM with a narrow QRS complex. In a third-degree heart block, about 61% take place at the bundle branch-Purkinje system, 21% at the AV node, and 15% at the bundle of His. AV block may be ruled out with an ECG indicating "a 1:1 relationship between P waves and QRS complexes." Ventricular bradycardias occurs with sinus bradycardia, sinus arrest, and AV block. Treatment often consists of the administration of atropine and cardiac pacing. Infantile
For infants, bradycardia is defined as a heart rate less than 100 BPM (normal is around 120–160 BPM). Premature babies are more likely than full-term babies to have apnea and bradycardia spells; their cause is not clearly understood. The spells may be related to centers inside the brain that regulate breathing which may not be fully developed. Touching the baby gently or rocking the incubator slightly will almost always get the baby to start breathing again, which increases the heart rate. Medications (theophylline or caffeine) can be used to treat these spells in babies if necessary. Neonatal intensive-care unit (NICU) standard practice is to electronically monitor the heart and lungs for this reason. Causes
Bradycardia arrhythmia may have many causes, both cardiac and non-cardiac.