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.
Digoxin at ordinary doses changes the ECG on purpose-free days too: a downsloping, sagging ST depression that curves back up (the reverse tick, or Salvador Dali's moustache), mostly where the R waves are tall, flattened or biphasic T waves, and a short QT. That's the effect, and on its own it only tells you the patient takes the drug. Toxicity shows up as rhythm trouble: frequent PVCs, bradycardia, AV block, atrial tachycardia with block, regularized AF, bidirectional VT.
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.
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.
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.
Flattened T waves, ST depression and prominent U waves (best in V2-V3) that can merge with the T to look like a long QT.
A short QT (QTc under 350 ms): the ST segment almost disappears, so the T wave starts right off the QRS.
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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