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

Electrocardiogram

Associate Professor Curtin Medical School, Curtin University. Emergency physician MA (Oxon) MBChB (Edin) FACEM FFSEM Sir Charles Gairdner Hospital.  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) Adult/Paediatric 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

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  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