Junctional rhythm
Junctional rhythm | |
---|---|
ECG of junctional rhythm | |
Specialty | Cardiology/electrophysiology |
Diagnostic method | ECG |
Treatment | Varies based on underlying cause[1] |
Junctional rhythm also called nodal rhythm
Under normal conditions, the heart's sinoatrial node(SA node) determines the rate by which the organ beats – in other words, it is the heart's "pacemaker". The electrical activity of sinus rhythm originates in the sinoatrial node and depolarizes the atria. Current then passes from the atria through the atrioventricular node and into the bundle of His, from which it travels along Purkinje fibers to reach and depolarize the ventricles. This sinus rhythm is important because it ensures that the heart's atria reliably contract before the ventricles.[citation needed]
In junctional rhythm, however, the sinoatrial node does not control the heart's rhythm – this can happen in the case of a block in conduction somewhere along the pathway described above, or in sick sinus syndrome, or many other situations.
Junctional rhythm can be diagnosed by looking at an
Classification
Junctional bradycardia
Junctional bradycardia is a rhythm that still originates in the AV node or bundle of His, but simply beats at a rate less than 40 beats per minute.[8]
Junctional escape rhythm
Junctional escape rhythm is a rhythm that still originates in the AV node or bundle of His, but beats at the intrinsic automaticity of the AV node, between 40 and 60 beats per minute.[9]
Accelerated junctional rhythm
Accelerated junctional rhythm is when the rhythm of emerged impulses is more than 40 to 60 beats per minute, which is the natural range of the junction. It happens in some instances such as digoxin toxicity, and usually has a rate of between 60 and 100 bpm.[10]
Junctional tachycardia
Junctional tachycardia is a rhythm that still originates in the AV node or bundle of His, but simply beats at a rate above 100 beats per minute.[1]
Presentation
The presentation and symptoms a patient can present with are varied and often dependent on the underlying cause of the junctional rhythm. Patient's can be
Causes
Anything that impairs the SA node can potentially lead to a junctional rhythm. Some examples below:[1]
- Chest trauma
- Ischemic heart disease
- Sick sinus syndrome
- Myocarditis
- Hypothyroidism
- Hyperkalemia
- Muscular dystrophy
- Certain medications
- Other neuromuscular disorders
Diagnosis
ECG findings
The first finding is that junctional rhythms are regular rhythms. This means that the time interval between beats stays constant. The next normal finding is a normal QRS. Since the impulse still travels down the bundle of His, the QRS will not be wide. Junctional rhythms can present with either bradycardia, a normal heart rate, or tachycardia.[8] The most obvious abnormal finding will be abnormal P waves. One of three options can occur:[11]
1. There are no P waves. This is because of either failure of retrograde flow to the atria or the P wave is hidden in the QRS. If the P wave is hidden that implies the atria depolarize at the same time as the ventricles.
2. There are inverted P waves prior to the QRS complex. This is because of retrograde flow to the atria causing depolarization prior to the ventricular contraction. Since the depolarization is occurring in the opposite direction, the P wave deflection is inverted.
3. There are inverted P waves after the QRS complex. This is because of retrograde flow to the atria after ventricular contraction.
Treatment
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Epidemiology
Junctional rhythm is seen equally in men and women, and can be seen intermittently in young children and athletes, especially during sleep. It occurs commonly in patients with sinus node dysfunction. 1/600 cardiology patients over the age of 65 have sinus node dysfunction.[1]
See also
References
- ^ PMID 29939537.
- ISSN 0096-8994.)
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: CS1 maint: multiple names: authors list (link - ^ Merriam-Webster dictionary > Junctional rhythm Retrieved September 2010
- ^ a b Beinart, MD, Sean (11 January 2022). "Junctional Rhythm: Background, Pathophysiology, Etiology". eMedicine.Medscape.
- ^ medical dictionary http://medical-dictionary.thefreedictionary.com/retrograde+conduction
- ISBN 9780323399685.
- ^ Abnormalities in the ECG measurement http://library.med.utah.edu/kw/ecg/ecg_outline/Lesson4/index.html#PRinterval
- ^ a b "Junctional Rhythm: Causes, Symptoms and Treatment". Cleveland Clinic.
- PMID 32491596.
- ISBN 9781582553955.
- ^ "ECG Study Guide".