The QT interval corresponds to the duration of a beat of the heart which occurs during split seconds; the electric activity of the cardiac muscle is prepared for the next beat.

Sketch of a Long QT

An electrocardiogram (ECG) makes it possible to record all the electric activity of the muscle of the heart. The waves are transcribed and taken as locates for the calculation of the QT which is carried out by measuring the space which begins with Q undulated until the end from the wave T, the main thing mark bench for the QT. The QT is regarded as prolonged when time put to traverse the interval is produced with - above 400 ms. However in the majority of the cases, the men have a QT interval shorter than the women. The lengthening of QT interval is always associated with an abnormal gene on a potassic, sodic or calcic channel.

This lengthening QT predisposes the patient with arrhythmias (twists of points) which are more serious among women.

For approximately 10% of the patients one finds a normal QT interval on the ECG and in nearly 30 % of the cases, the interval is prolonged little or limit, of or the interest to carry out, other tests and not to exclude the possibility of a LQTS at these people.


-Last update-august 29 2008-

Copyright2008 -Long QT syndrome association-