Detection of U wave activity in healthy volunteers by high-resolution magnetocardiography.

Introduction: The purpose of our study was to prove the existence of the U wave using magnetocardiograms (MCGs).

Methods: The 31-channel MCGs of 25 healthy volunteers were recorded. The onset of the U wave was defined by newly developed spatial correlation analysis; and the end, by different approaches.

Results: A U wave could be proved in all volunteers. In 10 volunteers (heart rate, 57 +/- 19 beats/min) in whom the U wave was found to be separated from the following P wave, the U wave's end could be determined as a threshold value (U wave duration, 310 +/- 24 milliseconds). In 15 volunteers (heart rate, 70 +/- 38 beats/min), the end of the U waves was concealed by a continuous transition of the U waves into the following P waves.

Conclusions: The U wave seems to be a regular phenomenon and has a distinct spatiotemporal assembly.