R Wave Peak Time RWPT

R wave peak time, also known as intrinsicoid deflection, is the time from onset of earliest Q wave 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
Prolonged R-wave peak time aVL
Prolonged R-wave peak time in aVL due to left anterior fascicular block

RWPT in wide QRS complex tachycardia

R-wave peak time (RWPT) may be useful 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

Example 1
  • Ventricular tachycardia
  • Positive deflection wide QRS
  • R-wave peak time (RWPT) >50 ms

Example 2
  • Ventricular tachycardia
  • Negative deflection wide QRS
  • R-wave peak time (RWPT) >50 ms

Example 3
  • Supraventricular tachycardia with aberrancy
  • Negative deflection wide QRS
  • R-wave peak time (RWPT) <50 ms

References

Advanced Reading

Online

Textbooks


LITFL Further Reading

ECG LIBRARY 700

ECG LIBRARY

Electrocardiogram

Emergency physician MA (Oxon) MBChB (Edin) FACEM FFSEM with a passion for rugby; medical history; medical education; and asynchronous learning #FOAMed evangelist. Co-founder and CTO of Life in the Fast lane | Eponyms | Books | Twitter |

MBBS (UWA) CCPU (RCE, Biliary, DVT, E-FAST, AAA) Emergency Medicine Advanced Trainee in Melbourne, Australia. Special interests in diagnostic and procedural ultrasound, medical education, and ECG interpretation. Editor-in-chief of the LITFL ECG Library. Twitter: @rob_buttner

One comment

  1. RWPT in WCT diagnosis? Neither specific [85.3% (80.6–89.3)] nor sensitive [62.0% (57.6–66.2)]. But useful when combined with other criteria in VT SCORE method. Europace (2016) 18, 578–584.
    Congratulation on your web page., Marek

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