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

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1. Dominant R wave in V1

Causes of Dominant R wave in V1

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Examples of Dominant R wave in V1

Normal paediatric ECG (2 yr old)

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Right Ventricular Hypertrophy (RVH)

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Right Bundle Branch Block (RBBB)

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Posterior MI

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Wolff-Parkinson-White (WPW) Type A

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Leads V1 and V3 reversed

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Muscular dystrophy

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2. Dominant R wave in aVR

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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

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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)

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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

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Ventricular Tachycardia

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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).

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ECG Library Basics

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Advanced Reading

Online

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

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LITFL Further Reading

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