R Wave Peak Time RWPT

R Wave Peak Time (Intrinsicoid deflection)

The time from the onset of the earliest Q or R wave to the peak of the R wave in the lateral leads (aVL, V5-6).

• Represents the time taken for excitation to spread from the endocardial to the epicardial surface of the left ventricle.
• R-wave peak time is said to be prolonged if > 45ms.
• Additionally used in Lead II in the differentiation of Ventricular Tachycardia (VT) and Supraventricular Tachycardia (SVT) with aberrancy.

Causes of Prolonged RWPT

• Left anterior fascicular block
• Left ventricular hypertrophy
• Left bundle branch block

Prolonged R-wave peak time in aVL due to left anterior fascicular block

RWPT in wide QRS complex tachycardia

R-wave peak time (RWPT) can be used in differentiating ventricular tachycardia (VT) from supraventricular tachycardia (SVT) in patients with wide QRS complex tachycardia

RWPT duration is measured in Lead II from the onset of QRS depolarization until the first change of polarity (with both positive or negative QRS deflection)

Studies in 2010 and 2013 demonstrated RWPT ≥ 50 ms in lead II to be a simple, reproducible, sensitive and specific for ventricular tachycardia.

However, more recent studies suggest RWPT of 50 ms may be optimal to differentiate between VT and SVT with RBBB and LAFB, but not with LBBB

• Ventricular tachycardia.
• Positive deflection wide QRS
• R-wave peak time (RWPT) >50 ms
  

• Ventricular tachycardia.
• Negative deflection wide QRS
• R-wave peak time (RWPT) >50 ms
  

• Supraventricular tachycardia with aberrancy.
• Negative deflection wide QRS
• R-wave peak time (RWPT) <50 ms
  

Reference

• Pava LF, Perafán P, Badiel M, Arango JJ, Mont L, Morillo CA, Brugada J. R-wave peak time at DII: A new criterion for differentiatingbetween wide complex QRS tachycardias. Heart Rhythm. 2010 Jul;7(7):922-6. [PMID 20215043]
  
• Datino T, Almendral J, Avila P, González-Torrecilla E, Atienza F, Arenal A, Fernández-Avilés F. Specificity of electrocardiographic criteria for the differential diagnosis of wide QRS complex tachycardia in patients with intraventricular conduction defect. Heart Rhythm. 2013 Sep;10(9):1393-401. [PMID 23851057]
  
• Yu M et al. R-Wave Peak Time at Lead II in Adults With Ventricular Premature Beats, Bundle Branch Block and Left Anterior Fascicular Block. Am J Med Sci. 2018 Jan;355(1):44-47 [PMID 29289261]
  

LITFL Further Reading

• ECG Library Basics – Waves, Intervals, Segments and Clinical Interpretation
• ECG A to Z by diagnosis – ECG interpretation in clinical context
• ECG Exigency and Cardiovascular Curveball – ECG Clinical Cases
• 100 ECG Quiz – Self-assessment tool for examination practice
• ECG Reference SITES and BOOKS – the best of the rest

Advanced Reading

• Brady WJ, Truwit JD. Critical Decisions in Emergency and Acute Care Electrocardiography
• Surawicz B, Knilans T. Chou’s Electrocardiography in Clinical Practice: Adult and Pediatric
• Wagner GS. Marriott’s Practical Electrocardiography 12e
• Chan TC. ECG in Emergency Medicine and Acute Care
• Rawshani A. Clinical ECG Interpretation
• Mattu A. ECG’s for the Emergency Physician
• Hampton JR. The ECG In Practice, 6e