T wave alternans

A periodic beat-to-beat variation in the amplitude or shape of the T wave may be termed T wave alternans.

Microvolt T wave Alternans (MTWA)

Valsalva or stress testing can prolong the QT interval, produce T wave alternans, and reveal notched T waves, especially during the early recovery phase.

Microvolt T wave alternans is defined as an alternation in the morphology of the T wave in an every other beat or AB-AB pattern.

Most modern references to TWA refer to microvolt T wave alternans (MTWA), a non-invasive heart test that can identify patients who are at increased risk of sudden cardiac death.

Additional features that are sometimes present include a prominent U wave, abnormal contour of T or TU waves, T wave alternans, a subnormal spontaneous sinus rate (especially in children), and sinus pauses.

Microvolt T wave alternans is a variant of T wave alternans that detects T wave alternans signals as small as one-millionth of a volt.