Junctional bradycardia: Difference between revisions
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'''Cardiovascular''' | '''Cardiovascular''' | ||
|style="height:100px"; style="width:75%" border="1" bgcolor="Beige" | [[Acute coronary syndrome]], [[acute rheumatic fever]], [[Andersen cardiodysrhythmic periodic paralysis]], [[Brugada syndrome]], [[cardiac tumor#heart in lymphomas|cardiac lymphoma]], [[cardiac tumor]], [[Carotid sinus hypersensitivity|cardioinhibitory syncope]], [[congenital heart disease]], [[congestive heart failure]], [[reperfusion injury|coronary reperfusion therapy]], [[dilated cardiomyopathy]], [[hypertensive heart disease]], [[hypertrophic cardiomyopathy]], [[ischemic heart disease]], [[Jervell and Lange-Nielsen syndrome]], [[long QT syndrome]], [[myocardial infarction]], [[myocardial rupture]], [[myocarditis]], [[NSTEMI]], [[pericarditis]], [[Romano-Ward syndrome]], [[sick sinus syndrome]], [[sinus arrest]], [[sinus bradycardia]], [[ | |style="height:100px"; style="width:75%" border="1" bgcolor="Beige" | [[Acute coronary syndrome]], [[acute rheumatic fever]], [[Andersen cardiodysrhythmic periodic paralysis]], [[Brugada syndrome]], [[cardiac tumor#heart in lymphomas|cardiac lymphoma]], [[cardiac tumor]], [[Carotid sinus hypersensitivity|cardioinhibitory syncope]], [[congenital heart disease]], [[congestive heart failure]], [[reperfusion injury|coronary reperfusion therapy]], [[dilated cardiomyopathy]], [[hypertensive heart disease]], [[hypertrophic cardiomyopathy]], [[ischemic heart disease]], [[Jervell and Lange-Nielsen syndrome]], [[long QT syndrome]], [[myocardial infarction]], [[myocardial rupture]], [[myocarditis]], [[NSTEMI]], [[pericarditis]], [[Romano-Ward syndrome]], [[sick sinus syndrome]], [[sinus arrest]], [[sinus bradycardia]], [[sinus node disease|sinus node fibrosis]], [[STEMI]], [[tachycardia-bradycardia syndrome]], [[Timothy syndrome]], [[valvular heart disease]] | ||
|- | |- | ||
|bgcolor="LightSteelBlue"| '''Chemical/Poisoning''' | |bgcolor="LightSteelBlue"| '''Chemical/Poisoning''' | ||
Revision as of 03:13, 26 August 2013
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Mugilan Poongkunran M.B.B.S [2]
Synonyms and keywords: Junctional escape; junctional escape rhythm
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
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.
Causes
Life Threatening Causes
Life-threatening causes include conditions which may result in death or permanent disability within 24 hours if left untreated.
- Acute coronary syndrome
- Acute hyperkalemic renal failure
- Diabetic ketoacidosis
- Myocardial rupture
- NSTEMI
- Organophosphate poisoning
- Parathion poisoning
- Poisonous spider bites
- Severe brain injury
- STEMI
Common Causes
- Acetylcholine
- Acute rheumatic fever
- Amiodarone
- Antiarrhythmic agents
- Beta-blockers
- Calcium channel blockers
- Cardiac catheterization
- Digitalis toxicity
- Dilated cardiomyopathy
- Diltiazem
- Hyperkalemia
- Hypermagnesemia
- Hypertensive heart disease
- Ischemic heart disease
- Methylprednisolone
- Phenytoin
- Sick sinus syndrome
- Sinus arrest
- Sinus bradycardia
- STEMI
- Verapamil
Causes by Organ System
Causes in Alphabetical Order
Epidemiology and Demographics
Age
Benign junctional rhythms are common during sleep in both children and athletic young adults.
Gender
Males and females are affected equally.
Natural History, Complications and Prognosis
The natural history and prognosis of the disease depends upon the underlying cause that triggered the junctional escape rhythm. A junctional escape rhythm during sleep is benign in children and young adults.
Diagnosis
Symptoms
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:
Physical Examination
Vitals
Pulse
The pulse is regular at a rate of 40 to 60 beats per minute.
Neck
- Cannon a waves may be present if there is delayed atrial contraction against a closed tricuspid valve
Laboratory Findings
Based upon the patient's history and demographics, consideration should be given to checking the following:
- Digoxin levels
- Lyme titers in patients where the disease is endemic
Electrocardiography
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:
- AV dissociation
- Complete heart block
- Digitalis toxicity
- Sinus arrest
- Sinus bradycardia
- ST elevation MI
- The rate is 40-60 beats per minute.
- The rate is generally regular.
- The QRS complex is narrow.
- 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.
- The p wave may be buried within the QRS complex and may not be discernable.
- A slow AV nodal reentry tachycardia (AVNRT) should be excluded.
EKG Examples
Shown below is an EKG with a nodal escape rhythm. Note the lack of P or P' waves. 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.
Copyleft images obtained courtesy of ECGpedia, http://en.ecgpedia.org.
Example of junctional escape rhythm / junctional bradycardia on telemetry:
{{#ev:youtube|S2xnOJfZOPI}}
Holter / Cardiac Event Monitoring
A cardiac event monitor may be helpful in patients with transient symptoms or palpitations to exclude other rhythms such as ventricular tachycardia.
Electrophysiologic Studies
- There is normal conduction in the His bundle, and the His-ventricular interval is normal.
- Preceding each QRS, there should be a His bundle depolarization
- AV conduction is variable
- VA conduction is variable
Treatment
Acute Management
- Avoid drugs that suppress the AV node as the junctional bradycardia may be the patient's only escape rhythm
- Treat symptomatic digitalis toxicity with atropine and digoxin immune Fab (Digibind)
Asymptomatic Patients
- Among healthy patients with heightened vagal tone, no treatment is necessary
Symptomatic Patients
- Permanent pacemaker placement in indicated in symptomatic patients with:
- Complete heart block
- High grade AV block
- Sick sinus syndrome
References
- ↑ McGregor A, Hurst E, Lord S, Jones G. "Bradycardia following retinoic acid differentiation syndrome in a patient with acute promyelocytic leukaemia". BMJ Case Rep. doi:10.1136/bcr.02.2012.5848. PMID 22778455.
- ↑ Cannillo M, Frea S, Fornengo C, Toso E, Mercurio G, Battista S; et al. (2013). "Berberine behind the thriller of marked symptomatic bradycardia". World J Cardiol. 5 (7): 261–4. doi:10.4330/wjc.v5.i7.261. PMC 3722425. PMID 23888197.
- ↑ Mehlsen J, Kaijer MN, Mehlsen AB (2008). "Autonomic and electrocardiographic changes in cardioinhibitory syncope". Europace. 10 (1): 91–5. doi:10.1093/europace/eum237. PMID 17971422.
- ↑ Isbister GK (2002). "Delayed asystolic cardiac arrest after diltiazem overdose; resuscitation with high dose intravenous calcium". Emerg Med J. 19 (4): 355–7. PMC 1725910. PMID 12101159.
- ↑ Brembilla-Perrot B, Muhanna I, Nippert M, Popovic B, Beurrier D, Houriez P; et al. (2005). "Paradoxical effect of isoprenaline infusion". Europace. 7 (6): 621–7. doi:10.1016/j.eupc.2005.06.012. PMID 16216767.
- ↑ Guillén EL, Ruíz AM, Bugallo JB (1998). "Hypotension, bradycardia, and asystole after high-dose intravenous methylprednisolone in a monitored patient". Am J Kidney Dis. 32 (2): E4. PMID 10074612.
- ↑ Landovitz RJ, Sax PE (1999). "Symptomatic junctional bradycardia after treatment with nelfinavir". Clin Infect Dis. 29 (2): 449–50. doi:10.1086/520237. PMID 10476763.
- ↑ Zyśko D, Gajek J, Agrawal AK, Rudnicki J (2012). "[The relevance of junctional rhythm during neurocardiogenic reaction provoked by tilt testing]". Kardiol Pol. 70 (2): 148–55. PMID 22427080.
- ↑ Cohen AS, Matharu MS, Goadsby PJ (2007). "Electrocardiographic abnormalities in patients with cluster headache on verapamil therapy". Neurology. 69 (7): 668–75. doi:10.1212/01.wnl.0000267319.18123.d3. PMID 17698788.