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| {{SI}} | | {{Junctional bradycardia}} |
| {{CMG}}
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| {{SK}} Junctional escape; junctional escape rhythm
| | '''For patient information, click [[Junctional bradycardia (patient information)|here]]''' |
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| ==Overview==
| | {{CMG}}; {{AE}} {{M.P}} |
| 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.
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| ==Pathophysiology==
| | {{SK}} Junctional escape; junctional escape rhythm |
| Normally, the [[atrioventricular node]] ([[AVN]]) can generate an escape rhythm of 40-60 beats per minute in case the [[sinoatrial node]] ([[SA node]]) or atrial pacemakers fail ([[sinus arrest]]) or slow ([[sinus bradycardia]]) or if there is [[complete heart block]]. This [[junctional escape rhythm]] generates a normal, narrow [[QRS complex]] rhythm at a rate below 60 beats per minute ([[junctional bradycardia]]) as the electrical impulses once they are generated are conducted with normal velocity down the usual pathways. [[Retrograde P waves]] (i.e. upside down) [[P waves]] due to retrograde or backward conduction may or may not be present.
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| ==Causes== | | ==[[Junctional bradycardia overview|Overview]]== |
| * [[Acute MI]]
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| * [[Acute rheumatic fever]]
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| * [[Antiarrhythmic agents]]
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| * [[Beta-blockers]]
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| * [[Calcium channel blockers]]
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| * [[Complete heart block]]
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| * [[Conduction system disease]]
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| * [[Digitalis toxicity]]
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| * [[Diphtheria]]
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| * Healthy response during sleep in patients with [[heightened vagal tone]]
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| * [[Heart surgery]] particularly [[valve replacement]] or surgery for [[congenital heart disease]]
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| * [[Ischemic heart disease]]
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| * [[Lyme disease]]
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| * [[NSTEMI]]
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| * [[Sick sinus syndrome]]
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| * [[Sinus arrest]]
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| * [[Sinus bradycardia]]
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| * [[STEMI]] particularly inferior MI involving the [[posterior descending artery]] causing ischemia of the [[AV node]] due to poor perfusion in the [[AV nodal artery]]
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| ==Epidemiology and Demographics== | | ==[[Junctional bradycardia historical perspective|Historical Perspective]]== |
| ===Age===
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| Benign junctional rhythms are common during sleep in both children and athletic young adults.
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| ===Gender=== | | ==[[Junctional bradycardia classification|Classification]]== |
| Males and females are affected equally.
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| ==Natural History, Complications and Prognosis== | | ==[[Junctional bradycardia pathophysiology|Pathophysiology]]== |
| The natural history and prognosis of the disease depends upon the underlying cause that triggered the junctional escape rhythm.
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| A [[junctional escape rhythm]] during sleep is benign in children and young adults.
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| ==Diagnosis== | | ==[[Junctional bradycardia causes|Causes]]== |
| ===Symptoms===
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| Symptoms are more likely if the atrial rate is faster than the junctional rate (if [[AV dissociation]] or [[complete heart block]] is present) as compared with the scenario whereby the junctional rate is faster than the atrial rate. The following symptoms may be present:
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| * [[Dyspnea]]
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| * [[Fatigue]]
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| * [[Lightheadedness]]
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| * [[Palpitations]]
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| * [[Presyncope]]
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| * [[Reduced exercise tolerance]]
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| * [[Syncope]]
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| ===Physical Examination=== | | ==[[Junctional bradycardia differential diagnosis|Differentiating Junctional bradycardia from other Disorders]]== |
| ====Vitals====
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| =====Pulse=====
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| The [[pulse]] is regular at a rate of 40 to 60 beats per minute.
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| ====Neck==== | | ==[[Junctional bradycardia epidemiology and demographics|Epidemiology and Demographics]]== |
| * [[Cannon a waves]] may be present if there is delayed atrial contraction against a closed [[tricuspid valve]]
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| ===Laboratory Findings=== | | ==[[Junctional bradycardia risk factors|Risk Factors]]== |
| Based upon the patient's history and demographics, consideration should be given to checking the following:
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| * [[Digoxin]] levels
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| * [[Lyme titers]] in patients where the disease is endemic
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| ===Electrocardiography=== | | ==[[Junctional bradycardia natural history, complications and prognosis|Natural History, Complications and Prognosis]]== |
| A 12 lead EKG should be obtained to evaluate the rhythm. In so far as it may alter treatment, any co-existing rhythm disturbance that may have precipitated junctional bradycardia should be ascertained such as:
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| * [[AV dissociation]]
| | ==Diagnosis== |
| * [[Complete heart block]]
| | [[Junctional bradycardia history and symptoms|History and Symptoms]] | [[Junctional bradycardia_physical_examination|Physical Examination]] | [[Junctional bradycardia laboratory findings|Laboratory Findings]] | [[Junctional bradycardia electrocardiogram|Electrocardiogram]] | [[Junctional bradycardia EKG examples|EKG Examples]] | [[Junctional bradycardia chest x-ray|Chest X Ray]] | [[Junctional bradycardia echocardiography|Echocardiography]] | [[Junctional bradycardia cardiac MRI|Cardiac MRI]] | [[Junctional bradycardia coronary angiography|Coronary Angiography]] |
| * [[Digitalis toxicity]]
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| * [[Sinus arrest]]
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| * [[Sinus bradycardia]]
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| * [[ST elevation MI]]
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| * The rate is 40-60 beats per minute.
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| * The rate is generally regular.
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| * The [[QRS]] complex is narrow.
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| * [[Retrograde p waves]] may be present due to retrograde conduction from the AV node. The p waves will be inverted in leads II and III.
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| * The [[p wave]] may be buried within the [[QRS]] complex and may not be discernable.
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| * A slow [[AV nodal reentry tachycardia]] ([[AVNRT]]) should be excluded.
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| ===EKG Examples===
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| The EKG below shows a nodal escape rhythm. Note the lack of P or [[P' wave]]s. Often the P' wave is hidden in the QRS as the nodal escape conducts down to the ventricle and up to the atrium in a fashion such that the QRS and P' wave occur simultaneously.
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| [[File:Nodal escape rhythm1.jpg|center|500px]] | |
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| Copyleft images obtained courtesy of ECGpedia, http://en.ecgpedia.org.
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| ----
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| Example of junctional escape rhythm / junctional bradycardia on telemetry:
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| {{#ev:youtube|S2xnOJfZOPI}}
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| ===Holter / Cardiac Event Monitoring===
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| A cardiac event monitor may be helpful in patients with transient symptoms or [[palpitations]] to exclude other rhythms such as [[ventricular tachycardia]].
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| ===Electrophysiologic Studies===
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| * There is normal conduction in the [[His bundle]], and the His-ventricular interval is normal.
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| * Preceding each [[QRS]], there should be a [[His bundle]] depolarization
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| * AV conduction is variable
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| * VA conduction is variable
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| ==Treatment== | | ==Treatment== |
| ===Acute Management===
| | [[Junctional bradycardia medical therapy|Medical Therapy]] | [[Junctional bradycardia electrical cardioversion|Electrical Cardioversion]] | [[Junctional bradycardia ablation|Ablation]] | [[Junctional bradycardia surgery|Surgery]] | [[Junctional bradycardia primary prevention|Primary Prevention]] | [[Junctional bradycardia secondary prevention|Secondary Prevention]] | [[Junctional bradycardia cost effectiveness of therapy|Cost-Effectiveness of Therapy]] | [[Junctional bradycardia future or investigational therapies|Future or Investigational Therapies]] |
| * Avoid drugs that suppress the [[AV node]] as the junctional bradycardia may be the patient's only escape rhythm
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| * Treat symptomatic [[digitalis toxicity]] with [[atropine]] and [[digoxin immune Fab]] ([[Digibind]])
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| ===Asymptomatic Patients===
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| *Among healthy patients with heightened vagal tone, no treatment is neccessary
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| ===Symptomatic Patients=== | | ==Case Studies== |
| * Permanent pacemaker placement in indicated in symptomatic patients with:
| | [[Junctional bradycardia case study one|Case #1]] |
| :* [[Complete heart block]]
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| :* High grade [[AV block]]
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| :* [[Sick sinus syndrome]]
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| ==Related Chapters== | | ==Related Chapters== |
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| * [[Junctional tachycardia]] | | * [[Junctional tachycardia]] |
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| ==References==
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| {{Reflist|2}}
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| | [[Category:Disease]] |
| | [[Category:Electrophysiology]] |
| [[Category:Cardiology]] | | [[Category:Cardiology]] |
| [[Category:Electrophysiology]] | | [[Category:Arrhythmia]] |
| | [[Category:Emergency medicine]] |
| | [[Category:Intensive care medicine]] |
| | [[Category:Best pages]] |
| | [[Category:Up-To-Date cardiology]] |
| | [[Category:Up-To-Date]] |
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