Ker, James A.2010-11-122010-11-122010-09Ker, J 2010, 'The double U wave - should the electrocardiogram be interpreted echocardiographically?', Clinical Medicine Insights: Cardiology, vol. 4, pp. 77-83. [http://www.la-press.com/]1179-5468http://hdl.handle.net/2263/15271The U wave is still an electrocardiographic deflection of enigmatic origin. Numerous hypotheses on its origin have been formulated, but to date none has been conclusively proven. Recently, a report described the first case of bifid (or notched) U waves. Until then this phenomenon has only been described in the T wave. This is the first report of double U waves—two separate deflections, ascribed to an accessory papillary muscle. HYPOTHESIS: The presence of a double U wave will be associated with an accessory papillary muscle (s). MATERIALS AND METHODS: This is a retrospective analysis of 4729 patient files of patients who were evaluated at a cardiology practice. The 12-lead surface electrocardiogram was evaluated for the possible presence of a double U wave. In cases where a double U wave was found, the transthoracic echocardiogram was then scrutinized for the presence of an accessory papillary muscle. RESULTS: A total of 3 cases of a double U wave were found. In every case an accessory papillary muscle was clearly seen on the transthoracic echocardiogram. CONCLUSION: A double U wave is a new variant of an old electrocardiographic deflection of enigmatic origin. This variant may be associated with an accessory papillary muscle.en© the author(s), publisher and licensee Libertas Academica Ltd. This is an open access article. Unrestricted non-commercial use is permitted provided the original work is properly cited.U waveDoublePapillary muscleElectrocardiographyEchocardiographyArticle