ECG Blog #122 (RBBB - LPHB - Congenital Heart Disease - Pediatric - RVH - LVH)

The ECG in Figure-1 was obtained from a 6-year old boy. If no other history was available at the time you were asked to interpret this tracing — What would be your impression?

• Although this tracing is technically a bit suboptimal ... — this should not interfere with your overall interpretation.

Figure-1: 12-lead ECG obtained from a 6-year old boy. No history available at the time you are asked to interpret this tracing.

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Interpretation: The rhythm is sinus, as determined by upright P waves with a constant and normal PR interval in the long lead II rhythm strip at the bottom. However, there is marked sinus arrhythmia. The QRS complex is wide (about 0.11 second) — and manifests a morphology consistent with complete RBBB (rSR’ in V1; wide terminal S waves in leads I and V6). Additional findings of interest include the following:

• LPHB, as well as RBBB — suggested by the very steep initial descent to the S wave in lead I — with qR patterns seen in each of the inferior leads. (With simple RBBB — there should not be a predominant S wave in lead I with steep initial descent as seen here).
• Small and narrow (probably septal) q waves in the infero-lateral leads.
• A very prominent (tall) R’ in lead V1 (that exceeds 20mm in amplitude! ).
• ST-T wave depression (with a terminal positive T wave component) in leads V1,V2 that is at least in part secondary to the RBBB, though which seems more pronounced than is usually seen with simple RBBB.
• Some “extra” deflections — namely, the terminal S waves in leads II and aVF; and especially the multi-directional QRS complex in lead V2.
• Seemingly generous R wave amplitude in lateral chest leads (24mm in V5; 20mm in V6).

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Impression: Sinus arrhythmia, even when marked as seen here in Figure-1 — is not abnormal in an asymptomatic child. In addition — the small and narrow infero-lateral q waves are a common normal finding — and, lateral chest lead QRS amplitude is not outside the normal range for a child this age (See Tables in Additional Reading below). On the other hand — complete RBBB is abnormal, and of itself would merit further evaluation. However, much more than simple RBBB — we also see: i) LPHB (vs abnormal right axis deviation); ii) markedly increased R’ amplitude in lead V1; iii) what seems to be excessive ST-T wave change in V1,V2; and iv) some “extra QRS deflections” beyond that expected for simple RBBB. Although reliability of a taller-than-expected R’ deflection with RBBB in adults is of imperfect reliability for predicting RVH (Right Ventricular Hypertrophy) — the above combination of findings in a young child should strongly suggest RVH and some form of underlying structural heart disease (most likely CHD = Congenital Heart Disease).

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Clinical Follow-Up: It turns out that this 6-year old child had Transposition of the Great Arteries which was surgically corrected. The child has done well post-surgery, and he was asymptomatic at the time the ECG in Figure-1 was obtained.

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Clinical MESSAGE: Although most providers who are not in the field of pediatric cardiology are not called upon to interpret pediatric ECGs on a regular basis — many (if not most) adult providers do encounter pediatric ECGs from time to time. It is therefore important to at least be aware of “the Basics” for interpreting the ECG of our younger patients. Knowing the specific type of congenital heart disease most likely to account for a given set of abnormal ECG findings is far less important than recognizing whether what is seen is likely to be normal or abnormal considering the age of the patient. The KEY point to emphasize from this case — is that the ECG in Figure-1 is not normal for a 6-year old child. Further investigation is clearly indicated until the cause of the abnormal findings is found.

• The clinical reality, is that many children with surgically-corrected congenital heart disease are now surviving into adulthood. These patients make up a new population that adult providers will increasingly come into contact with, making awareness of the longterm effects of CHD more and more important.

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Acknowledgment: — My thanks to David McCarty (USA) for his permission to use this case and ECG.

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Additional Reading: I am not an expert in pediatric cardiology or pediatric ECG interpretation. However, I did oversee all ECGs done on pediatric patients in our 35-provider Primary Care Center for 3 decades. Below are links to some basic materials that may be of help to adult providers without regular exposure to pediatric ECGs.

• Regarding this Case: CLICK HERE — for more on Surgically-Corrected Transposition of the Great Arteries.
• PDF of the Chapter I wrote on Pediatric ECG Interpretation (from my 1998 ECG book, published by Mosby). Although written a while back ... the "Basics" are here, and they provide perspective and a way to approach interpretation of pediatric ECGs. (NOTE: This pdf reads much better if you download to your desktop (!) instead of trying to read from your browser).
• Pediatric R Wave Upper Limits.
• Pediatric S Wave Upper Limits (These 2 Tables are from Rijnbeek et al: Eur Heart J 22(8):702, 2001 — and they go beyond the simpler Tables I show in the PDF from my Chapter). When in doubt as to whether QRS amplitude is within or exceeds the normal range in a given lead for a child of a certain age — I look up the limits in a Table ...

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