R wave

R wave Overview

The R wave is the first upward deflection after the P wave. The R wave represents early ventricular depolarisation

Abnormalities of the R wave

There are three key R wave abnormalities:

1. Dominant R wave in V1
2. Dominant R wave in aVR
3. Poor R wave progression

1. Dominant R wave in V1

Causes of Dominant R wave in V1

• Normal in children and young adults
• Right Ventricular Hypertrophy (RVH)
  • Pulmonary Embolus
  • Persistence of infantile pattern
  • Left to right shunt
• Right Bundle Branch Block (RBBB)
• Posterior Myocardial Infarction (ST elevation in Leads V7, V8, V9)
• Wolff-Parkinson-White (WPW) Type A
• Incorrect lead placement (e.g. V1 and V3 reversed)
• Dextrocardia
• Hypertrophic cardiomyopathy
• Dystrophy
  • Myotonic dystrophy
  • Duchenne Muscular dystrophy

Examples of Dominant R wave in V1

Normal paediatric ECG (2 yr old)

Right Ventricular Hypertrophy (RVH)

Right Bundle Branch Block (RBBB)

Posterior MI

Wolff-Parkinson-White (WPW) Type A

Leads V1 and V3 reversed

• Note biphasic P wave (typically seen in only in V1) in lead “V3”

Muscular dystrophy

2. Dominant R wave in aVR

• Poisoning with sodium-channel blocking drugs (e.g. TCAs)
• Dextrocardia
• Incorrect lead placement (left/right arm leads reversed)
• Commonly elevated in ventricular tachycardia (VT)

Examples of Dominant R wave in aVR

Poisoning with sodium-channel blocking drugs

• Causes a characteristic dominant terminal R wave in aVR
• Poisoning with sodium-channel blocking agents is suggested if:
  • R wave height > 3mm
  • R/S ratio > 0.7

Dextrocardia

This ECG shows all the classic features of dextrocardia:

• Positive QRS complexes (with upright P and T waves) in aVR
• Negative QRS complexes (with inverted P and T waves) in lead I
• Marked right axis deviation
• Absent R-wave progression in the chest leads (dominant S waves throughout)

Left arm/right arm lead reversal

The most common cause of a dominant R wave in aVR is incorrect limb lead placement, with reversal of the left and right arm electrodes. This produces a similar pattern to dextrocardia in the limb leads but with normal R-wave progression in the chest leads. With LA/RA lead reversal:

• Lead I becomes inverted
• Leads aVR and aVL switch places
• Leads II and III switch places

Ventricular Tachycardia

3. Poor R wave progression

Poor R wave progression is described with an R wave ≤ 3 mm inV3 and is caused by:

• Prior anteroseptal MI
• LVH
• Inaccurate lead placement
• May be a normal variant

Note that absent R wave progression is characteristically seen in dextrocardia (see previous ECG).

ECG Library Basics

Advanced Reading

Online

• Wiesbauer F, Kühn P. ECG Mastery: Yellow Belt online course. Understand ECG basics. Medmastery
• Wiesbauer F, Kühn P. ECG Mastery: Blue Belt online course: Become an ECG expert. Medmastery
• Kühn P, Houghton A. ECG Mastery: Black Belt Workshop. Advanced ECG interpretation. Medmastery
• Rawshani A. Clinical ECG Interpretation ECG Waves
• Smith SW. Dr Smith’s ECG blog.

Textbooks

• Zimmerman FH. ECG Core Curriculum. 2023
• Mattu A, Berberian J, Brady WJ. Emergency ECGs: Case-Based Review and Interpretations, 2022
• Straus DG, Schocken DD. Marriott’s Practical Electrocardiography 13e, 2021
• Brady WJ, Lipinski MJ et al. Electrocardiogram in Clinical Medicine. 1e, 2020
• Mattu A, Tabas JA, Brady WJ. Electrocardiography in Emergency, Acute, and Critical Care. 2e, 2019
• Hampton J, Adlam D. The ECG Made Practical 7e, 2019
• Kühn P, Lang C, Wiesbauer F. ECG Mastery: The Simplest Way to Learn the ECG. 2015
• Grauer K. ECG Pocket Brain (Expanded) 6e, 2014
• Surawicz B, Knilans T. Chou’s Electrocardiography in Clinical Practice: Adult and Pediatric 6e, 2008
• Chan TC. ECG in Emergency Medicine and Acute Care 1e, 2004

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