by Gail Belsky. The term sleep disorder may suggest someone tossing and turning all night, but lying awake for hours with insomnia is just one example of many conditions that affect how you sleep and function during the day. In fact, you can have a sleep disorder and not even know it. Next: How long to snooze.
A U wave as seen on ECG. An electrocardiogram of an 18-year-old man showing U waves, most evident in lead V3. The U wave is a wave on an electrocardiogram that is not always seen. It is typically small, and, by definition, follows the T wave. U waves are thought to represent repolarization of the papillary muscles or Purkinje fibers.
In this issue of PACE, Nakagawa et. al. describe how changes in heart rate affect the morphology of the U waves in the electrocardiogram of two patient groups: 1) in patients with idiopathic ventricular tachycardia originating from the right ventricular outflow tract (RVOT-VT) and 2) in healthy controls.