title: U wave variability in the surface ECG.
abstract: A 72-year-old man with heart failure, left ventricular dysfunction (ejection fraction 20%), prior ischemic stroke, COPD, and exacerbation of chronic renal failure was admitted in our unit. Serum potassium was 6.1 mmol/L, calcium concentration was at the lower normal range 2.15 mmol/L, and NT-pro-BNP was 28,900 pg/mL. The surface 12-lead electrocardiogram (ECG) showed sinus rhythm at 60 bpm, PR interval 160 ms, QRS duration 115 ms, QT interval 460 ms, and left ventricular hypertrophy criteria. Negative T waves in leads I, II, aVL, and V4 -V6 were also seen. In leads V4 -V6 , negative U waves were observed in concordance with negative T waves. In all precordial leads, beat-to-beat U-wave polarity variability was observed as a polarity variation from negative to positive with associated and stable negative T waves, in a beat-to-beat alternate morphology.
authors.affiliation: Department of Cardiology, Specialistic Hospital, Gorlice, Poland.
authors.forename: Piotr
authors.initials: P
authors.lastname: Kukla
authors.forename: Adrian
authors.initials: A
authors.lastname: Baranchuk
authors.forename: Marek
authors.initials: M
authors.lastname: Jastrzębski
authors.forename: Leszek
authors.initials: L
authors.lastname: Bryniarski
mesh_terms: D000368:Aged; D001145:Arrhythmias, Cardiac / Q000150:complications* / Q000175:diagnosis; D053840:Brugada Syndrome; D000075224:Cardiac Conduction System Disease; D004562:Electrocardiography / Q000379:methods*; D006329:Heart Conduction System / Q000002:abnormalities*; D006333:Heart Failure / Q000150:complications*; D006801:Humans; D006947:Hyperkalemia / Q000150:complications*; D017379:Hypertrophy, Left Ventricular / Q000150:complications; D006996:Hypocalcemia / Q000150:complications*; D007676:Kidney Failure, Chronic / Q000150:complications; D008297:Male; D018487:Ventricular Dysfunction, Left / Q000150:complications*
keywords: U-wave variability; heart failure; hyperkalemia
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