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The "QT" interval is found on an electrocardiogram (ECG).
The QT represents the electrical activity of the heart. The start of the
QT interval is demonstrated in the figure below. It is measured
from the initiation of the QRS complex to the end of the T-wave.
The
duration of the QT-interval in normal people at a heart rate of 60 beats
per minute is between 350 and 440 milliseconds. In patients with
SQTS the duration of the QT interval has been between 210 and 340
milliseconds
Another finding in
patients with SQTS is the QT interval changes very little as the heart rate
changes. Normal individuals QT interval lengths when the heart
rate is slow, and shortens during fast heart rates. Patients with SQTS have a
near constant QT interval with slow heart rates and fast heart
rates.
Although these difference seem minor, they
are not found in the normal population, and have proven to be predispose
those with SQTS to arrhythmias.
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