Saturday, 11 April 2015

ECG of the Week - 6th April 2015 - Interpretation

This week's ECG is from a 32yr old female with a history of palpitations. She takes flecanide and verapamil. She presents to the Emergency Department complaining of palpitations for the last few hours. She is conscious, denies chest pain or dysponea and her blood pressure is normal.
Check out the comments on our original post here.

Click to enlarge
  • 132 bpm
  • Regular
  • Evidence of possible AV dissociation
    • Notching best seen in rhythm strip irregularly occurs at differing portions of QRS ( red circles in abridged rhythm strip below)
Abridged rhythm strip - atrial activity circled

  • Right / Inferior (105 deg)
  • QRS - Prolonged (100ms)
  • Discordant ST / T-wave changes
  • LBBB morphology
  • Broad Complex Tachycardia
General DDx include:
  • Ventricular tachycardia
  • SVT with aberrancy
  • SVT with pre-existing block
  • SVT with pre-excitation / WPW
  • Paced rhythm
  • Electrolyte abnormality / toxicological / environmental

 So what does our ECG show ?

The combination of LBBB morphology and right axis deviation is consistent with Right Ventricular Outflow Tract Tachycardia (RVOT). This is a type of monomorphic VT originating from the right outflow tract or tricuspid annulus it is commonly seen in structurally normal hearts and is usually haemodynamically well tolerated. RVOT can be terminated with vagal maneuvers, adenosine and is also sensitive to verapamil. 

Following vagal maneuvers the patient's subsequent ECG is below.

Post vagal maneuver
This ECG shows a combination of sinus rhythm and ventricular ectopics. Note the normal T wave morphology in the precordial leads, inferior axis and lack of epsilon wave in the sinus complexes. The ventricular ectopics share the same LBBB morphology and inferior / right axis seen in the first ECG and are occurring frequently. 

The patient was given iv verapamil and returned to consistent sinus rhythm, long term management will be with plan ablation therapy.

RVOT can also be seen in arrhythmogenic right ventricular dysplasia, you can read more about this condition in the Life in the Fast Lane ECG library (link below).

There is a great and brief overview of idiopathic ventricular tachycardias from the E-Journal of the ESC Council for Cardiology Practice that I would recommend:

References / Further Reading

Life in the Fast Lane

  • Chan TC, Brady WJ, Harrigan RA, Ornato JP, Rosen P. ECG in Emergency Medicine and Acute Care. Elsevier Mosby 2005.