title: Discordant U waves in the setting of hyperkalaemia.
abstract: Physiological U wave genesis occurs likely secondary to either late repolarisation of Purkinje fibres, or late repolarisation of some myocardial cells and/or delayed after depolarisation of the ventricular wall occurring during ventricular filling. Hypokalaemia has a well-known association with pathological 'U wave' which actually combines with the T wave (TU complex) and results from slowing of phase 3 of the action potential with resultant electrical interaction between the three myocardial layers. U waves usually tend to disappear in the setting of hyperkalaemia. We report an unusual case where hyperkalaemia and discordant U waves coexisted. We believe that this may have occurred as a result of partial clinical adaptation of cardiac myocytes to the long-standing effects of hyperkalaemia as the patient had underlying history of chronic kidney disease. We also discuss the possible mechanisms of the U wave genesis and the importance of different U wave morphologies encountered in the real clinical practice.
authors.affiliation: Department of Internal Medicine, Saint Vincent Hospital, University of Massachusetts Medical School, Worcester, Massachusetts, USA. lovids@hotmail.com
authors.forename: Lovely
authors.initials: L
authors.lastname: Chhabra
authors.forename: David H
authors.initials: DH
authors.lastname: Spodick
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003937:Diagnosis, Differential; D004562:Electrocardiography; D005260:Female; D005440:Fluid Therapy; D006801:Humans; D006947:Hyperkalemia / Q000188:drug therapy / Q000503:physiopathology* / Q000628:therapy; D011137:Polystyrenes / Q000627:therapeutic use; D016896:Treatment Outcome
chemical_list: D011137:Polystyrenes; C003321:polystyrene sulfonic acid