2021, Number 4
Cardiovasc Metab Sci 2021; 32 (4)
The U wave: an ignored wave filled with information
Duque-González, Laura; Gaviria-Aguilar, Maria C; Lopera-Mejía, Laura; Duque-Ramírez, Mauricio
ABSTRACT
The U wave was first described over more than 100 years. However, numerous hypothesis about its origin and clinical significance still exist. It corresponds to the sixth wave of the electrocardiogram (ECG), and its visibility depends, among others, on the heart rate, but it may be absent in 50-75% of cases. Its origin is a cause of debate; there are four crucial hypotheses about its genesis: 1) repolarization of purkinje fibers, 2) repolarization of papillary muscles, 3) M cells theory, and 4) mechanoelectrical theory. Variants of the U wave are prominent and inverted. The inverted U wave is associated with hypertension, coronary heart disease or valvular disease. The prominent U wave is related to bradycardia, hypokalemia, hypothermia, long QT syndrome or with the use of some medication like class Ia and III antiarrhythmics.