Right Ventricular Outflow Tract Tachycardia

Overview

Right ventricular outflow tract (RVOT) tachycardia is a form of monomorphic VT originating from the outflow tract of the right ventricle or occasionally from the tricuspid annulus. It is usually seen in patients without underlying structural heart disease.

The majority (80%) of outflow tract ventricular arrhythmias (OTVAs) originate from the RVOT. The RVOT is divided into rightward (free wall), anterior, leftward, and posterior (septal) parts. RVOT VT can originate from any of these sites but carry common ECG characteristics.

ECG features
  • LBBB morphology
  • Inferior axis
  • rS complex in V1 and R complex in V6
  • Precordial transition usually ≥ V3, with the exception of septal origin, which occurs at ≤ V3

Other general features of VT, such as AV dissociation, fusion and/or capture beats may also be present.


Causes
Idiopathic VT

RVOT tachycardia is most commonly a form of idiopathic VT, whereby no structural heart disease, metabolic/electrolyte abnormalities, or long QT syndrome can be found. There are two main forms of clinical presentation:

  • Repetitive, unsustained, monomorphic VT is the most common form seen in 60-90%
  • Exercise-induced sustained ventricular arrhythmias
Arrhythmogenic Right Ventricular Dysplasia (ARVD)

ARVD is a genetic disorder of myocardium in which there is fatty infiltration of the right ventricular free wall, and accounts for up to 10% of sudden cardiac death in individuals under 65 years of age. Affected individuals often present with exercise-induced episodes of VT accompanied by LBBB morphology.

Differentiation between idiopathic RVOT tachycardia and that caused by ARVD can be difficult and may rely on previous ECG findings as well as family history.


Clinical implications
  • RVOT tachycardia can be difficult to distinguish from SVT with LBBB
  • Inferior axis (+90 degrees) is usually the most differentiating feature, but other features of VT such as AV dissociation may be present

Treatment:

  • Acute termination of idiopathic RVOT tachycardia in a stable patient can be achieved by vagal manoeuvres or adenosine (6mg up to 24mg)
  • IV verapamil is an alternative if the patient has an adequate blood pressure reserve
  • RVOT tachycardia in ARVD does not terminate with adenosine

In stable patients with a regular broad complex tachycardia, adenosine is useful and safe as a diagnostic and potentially therapeutic agent.

In unstable patients, if there is doubt regarding the rhythm (SVT v VT), proceed to DCCV


Example ECGs
Example 1
ECG RVOT VT LBBB Inferior axis 2

RVOT tachycardia:

  • Regular broad complex tachycardia
  • LBBB-like morphology with rS complex in V1 and R complex in V6
  • Precordial transition at V3
  • Inferior axis (+ 90 degrees)

Example 2
ECG RVOT LBBB VT Inferior Axis

RVOT tachycardia:

  • Regular broad complex tachycardia
  • LBBB-like morphology with rS complex in V1 and R complex in V6
  • Precordial transition at V4
  • Inferior axis (+ 90 degrees)

Video Lessons

Professor Sanjay Sharma discusses Right Ventricular VT in ARVD.


Related Topics


References

Advanced Reading

Online

Textbooks


LITFL Further Reading

ECG LIBRARY 700

ECG LIBRARY

Electrocardiogram

MBBS (UWA) CCPU Emergency Medicine Advanced Trainee based in Melbourne, Australia. Co-author of the LITFL ECG Library. Likes Ultrasound, Echo, ECGs, and anything and everything with caffeine. Part of the 2021 ANZCEN Clinician Educator Incubator Programme | @rob_buttner | ECG Library |

Emergency Physician in Prehospital and Retrieval Medicine in Sydney, Australia. He has a passion for ECG interpretation and medical education | ECG Library |

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