Idioventricular rhythm
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Mahmoud Sakr, M.D. [2]
Synonyms and keywords: IVR
Overview
Normally, the SA node is responsible for triggering each heart beat that results in ventricular contraction. However, if the ventricle does not receive triggering signals at a rate high enough, the ventricular myocardium itself becomes the pacemaker or produces escape beats. This is called idioventricular rhythm.
Pathophysiology
Idioventricular rhythm originates in the ventricular area and the depolarization wave spreads either partially through the electrical conduction system or completely via direct cell-to-cell transmission. Idioventricular rhythm can occur as an escape rhythm, or as an increased automaticity of a single ventricular ectopic pacemaker. This increased automaticity may lead to rates that are faster than the intrinsic rate of the upper pacemakers. The intrinsic rate in idioventricular rhythm is most commonly between 30 and 50 BPM, but the rhythm can be anywhere from 20 to 50 BPM. The idioventricular complexes will have the morphological characteristics of the ventricular escape complex, two ventricular escape complexes, two ventricular escape complexes with associated AV dissociation or ectopic ventricular complexes.[1]
Causes
Life Threatening Causes
Idioventricular rhythm is a life-threatening condition and must be treated as such irrespective of the causes. Life-threatening conditions can result in death or permanent disability within 24 hours if left untreated.
Common Causes
- Acute rheumatic fever
- Amiodarone
- Beta-blockers
- Calcium channel blockers
- Cardiomyopathy
- Congestive heart failure
- Diabetic ketoacidosis
- Digoxin
- Hyperkalemia
- Hypermagnesemia
- Hypertensive heart disease
- Hypothermia
- NSTEMI
- Organophosphate poisoning
- Severe brain injury
Causes by Organ System
Causes in Alphabetical Order
Differentiating Idioventricular Rhythm from other Diseases
Below is a table to illustrate some of the similarities and disparities between different ventricular arrhythmias.
| example | regularity | atrial frequency | ventricular frequency | origin (SVT/VT) | p-wave | effect of adenosine | |
|---|---|---|---|---|---|---|---|
| Wide complex (QRS>0.12) | |||||||
| Ventricular Escape | [[Image:]] | irregular | ? | 1-2 bpm | ventricle (VT) | AV-dissociation | None |
| Idioventricular rhythm | [[Image:]] | regular (mostly) | ? | 20-50 bpm | ventricle (VT) | AV-dissociation | None |
| Ventricular Tachycardia | 
|
regular (mostly) | 60-100 bpm | 110-250 bpm | ventricle (VT) | AV-dissociation | no rate reduction (sometimes accelerates) |
| Ventricular Fibrillation | 
|
irregular | 60-100 bpm | 400-600 bpm | ventricle (VT) | AV-dissociation | none |
| Ventricular Flutter | 
|
regular | 60-100 bpm | 150-300 bpm | ventricle (VT) | AV-dissociation | none |
| Accelerated Idioventricular Rhythm | 
|
regular (mostly) | 60-100 bpm | 50-110 bpm | ventricle (VT) | AV-dissociation | no rate reduction (sometimes accelerates) |
| Torsade de Pointes | 
|
regular | 150-300 bpm | ventricle (VT) | AV-dissociation | no rate reduction (sometimes accelerates) | |
| Bundle-branch re-entrant tachycardia* | 
|
regular | 60-100 bpm | 150-300 bpm | ventricles (VT) | AV-dissociation | no rate reduction |
| (*) Bundle-branch re-entrant tachycardia is extremely rare | |||||||
References
- ↑ Miller, Geoffrey P.; Garcia, Tomas B. (2004). Arrhythmia recognition: the art of interpretation. Boston: Jones and Bartlett Publishers. ISBN 0-7637-2246-4.