Huge voltage (deep S in V1 plus tall R in V5 or V6 adding to 35 mm or more), with lateral ST depression and asymmetric T inversion, and ST elevation in V1-V3 that matches the deep S waves.
A thick left ventricle makes big forces: deep S waves in V1-V3 and tall R waves in I, aVL and V5-V6. Sokolow-Lyon adds the S in V1 to the taller R in V5 or V6, and 35 mm or more meets it. Strain is the repolarization that goes with it: ST depression and an asymmetric T inversion (slow down, quick back up) in the lateral leads. The ST elevation in V1-V3 is the deep S waves' mirror image, and it's the reason LVH is one of the commonest false STEMI calls. Hypertension is the usual cause. Voltage alone can be normal in a young, thin patient.
Each is a standard 12-lead: 2.5 seconds of each lead in four columns, with 10 seconds of lead II along the bottom, drawn to scale (25 mm a second, 10 mm a millivolt). The measurements are under each one.
ST elevation across V1-V4, from an occluded left anterior descending artery.
A QRS of 0.12 s or more with a deep, broad S (QS or rS) in V1 and a broad R with no Q wave in I, aVL, V5 and V6.
Horizontal ST depression across many leads, deepest in V4-V6, I and II, with ST elevation in aVR (bigger than any in V1): global subendocardial ischemia, not a territory.
A sagging, scooped ST depression (the reverse tick) where the R waves are tall, flattened T waves and a short QT. It means the patient takes digoxin, not that they're toxic.
The ECG tool in the app gives you a new 12-lead every time and walks you through reading it: rate, QRS, axis, then where the ST is up and down. It's part of the Paramedic level, and you can try 5 ECGs a day free.
Try the 12-lead drill
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