R Wave

Abnormalities of the R wave

• Dominant R wave in V1
• Dominant R wave in aVR
• Poor R wave progression

Causes of Dominant R wave in V1

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

 

Normal paediatric ECG (2 yr old)

 

Right Ventricular Hypertrophy (RVH)

 

Right Bundle Branch Block

 

 

Posterior MI

 

WPW (type A)

 

Leads V1 and V3 reversed

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

 

Muscular dystrophy

 

Dominant R wave in aVR

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

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

Poor R wave progression

Defined as an R wave ≤ 3 mm in V3

Causes

• 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).

Related Topics

• P wave
• Q wave
• T wave

Further Reading

• ECG BASICS — Waves, Intervals, Segments and Clinical Interpretation
• ECG CLINICAL CASES — Your favourite ECG’s placed in clinical context with a challenging Q&A approach
• ECG and Cardiology Eponymous Syndromes — Cheats guide to eponymous emancipation
• ECG Exam Template — a framework for the FACEM part 2 exam.
• ECG Reference Sites on the WEB — the best of the rest

References

• Surawicz B, Knilans TK. Chou’s Electrocardiography in Clinical Practice. 6th Edition. Saunders Elsevier 2008.
• Wagner, GS. Marriott’s Practical Electrocardiography (11th edition), Lippincott Williams & Wilkins 2007.

Author Credits