Reading the ECG: The Wide Complex

What this deck covers

Reading the ECG: The Wide Complex in twelve illustrated clinical cases with worked explanations – case presentations built around clinical images, radiology, teaching illustrations and real laboratory data, with the reference range beside every value a case quotes. This visual, data-interpretation style of practice suits candidates preparing for MRCPCH AKP in particular, alongside Saudi and Gulf licensing examinations such as the Arab Board, DHA and OMSB. Each case gives you a clinical vignette, four options, the correct answer, and an explanation of why each of the other three is wrong.

The twelve cases, in order

1. Measuring how wide a complex is
2. The same width, two different ages
3. Which side the delay is on
4. The same question, the other side
5. A spike before every complex
6. Wide when fast, narrow when slow
7. T waves that point the wrong way
8. Every chest lead facing one way
9. One narrow beat in a wide run
10. A complex between two shapes
11. A pattern that needs nothing done
12. What the P waves settle

What this deck teaches

• Measure it in the widest lead. From the first deflection of the complex to the point the segment begins. A complex that looks narrow in one lead can be wide in another.
• There is no single normal duration. The upper limit is shorter in an infant than in an adolescent, so a width is read against the age before it is called wide.
• Which side, from V1 and V6. A secondary R wave in V1 with a broad S wave laterally is one side. A broad notched R wave in V6 with a deep S wave in V1 is the other.
• A spike before every complex is a device. Sharp, narrow, and in front of each beat. It is not part of the complex and it is not measured as part of the width.
• Width that comes and goes with rate. A complex wide at speed and narrow when the rate falls is conduction that cannot keep up, not a complex that is wide in its own right.
• Repolarisation follows the complex. T waves pointing away from a wide QRS are expected. Reporting them as a separate abnormality is the common error.

Exam pearls from this deck

• A complex is as wide as its widest lead, not as its clearest one.
• A width is judged against the age, in the same way a voltage is.

The twelve worked cases in this deck, with the images and the full explanation of every option, are part of Pediatric Case Review membership. See what is included, or start with the free Pediatric Exam Review Sets.

More from this system: all cardiology illustrated case decks · cardiology board questions for bank-style drilling · the free Pediatric Exam Review Sets · pediatric reference values.