Junctional bradycardia overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Mugilan Poongkunran M.B.B.S [2]
Overview
Junctional bradycardia is a slow (40 to 60 beats per minute) narrow complex escape rhythm that originates in the atrioventricular node to compensate for slow or impaired conduction of pacemaker activity in the atrium.
Pathophysiology
Junctional bradycardia or an AV junctional escape is a delayed heartbeat originating from an ectopic focus somewhere in the AV junction to compensate for an SA node that is no longer handling the pacemaking activity.
Causes
Junctional bradycardia occurs when the rate of depolarization of the SA node falls below the rate of the AV node or when the electrical impulses from the SA node fail to reach the AV node because of SA or AV block. SA node fibrosis and inferior wall myocardial infarction causing sinus arrest may cause the AV node to become the dominant pacemaker of the heart.
Differentiating Junctional Bradycardia from other Diseases
Junctional bradycardia or junctional escape rhythm need to be differentiated from other bradycardia conditions which has the bundle of His or the ventricles as their pacemaker compensating for the failed SA node.
Epidemiology and Demographics
Junctional bradycardia is fairly uncommon. It can occur in any age group, however it is more likely to be observed in elderly people with underlying heart disease.
Natural History, Complications and Prognosis
Junctional bradycardia mostly results due to failure of impulse transmission from SA node. Its severity of symptoms depends on the underlying cause.
Diagnosis
History and Symptoms
Junctional bradycardia symptoms mostly are due to decrease cardiac output and may present with sometimes with loss of consciousness and syncope.
Physical Examination
Complete physical examination help determine any heart defects as a cause for junctional bradycardia and assess the severity of the condition.
Laboratory Findings
Junctional bradycardia patients may have no definite cause or may be the result of various other problems. If junctional bradycardia patients present with symptoms, a generalized approach is done to find the precipitating factors.
Electrocardiography
Junctional bradycardia or AV junction rhythm is usually caused by the absence of the electrical impulse from the SA node. This usually appears on an EKG with a normal QRS complex accompanied with an inverted P wave either before, during, or after the QRS complex.
Treatment
Medical Therapy
Treatment of junctional bradycardia depends on the severity of presentation. Atropine can be used to manage symptomatic patients.
Surgery
Junctional bradycardia patients should be placed on pacemaker if there is complete AV block or sick sinus syndrome.