A short QT (QTc under 350 ms): the ST segment almost disappears, so the T wave starts right off the QRS.
High calcium shortens the QT, mostly by squeezing out the ST segment, so the T wave seems to rise straight off the QRS. A QTc under 350 ms is short. Severe hypercalcemia can add Osborn waves and, at the extreme, ventricular arrhythmias. Think of it in cancer, myeloma or hyperparathyroidism, often in a dehydrated, confused patient. Digoxin shortens the QT too, but adds a sagging ST.
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.
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.
A long QT made by a long, flat ST segment, with a normal-looking T wave at the end of it.
Sinus rhythm, a normal axis, normal intervals, R waves growing from V1 to V5, and no ST elevation or depression.
T waves that are tall, narrow at the base and peaked, best seen in the chest leads. As potassium rises, the P wave flattens, the PR lengthens and the QRS widens.
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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