February 2023 Issue
ISSN 2689-291X
ISSN 2689-291X
Hypokalemia:
Electrocardiographic & Arrhythmic Manifestation!
Description & Discussion
Three electrocardiograms (EKGs) are presented below with variable degrees of hypokalemia. In Figure A, the potassium level is 3.2 mmol/L. Prominent U waves are indicated by the blue arrows adjacent to the T wave, long known to be a sign of hypokalemia [1], causing prolongation of the QT interval due to QT-U fusion [2].
In Figure B, the potassium level is 1.7 mmol/L. Tall U waves, which exceed the T waves in height and fuse with them, are evident as indicated by the red arrows [3]. In Figure C, the potassium level is 2.4 mmol/L. Prolonged QT interval is indicated by the orange arrow probably due to QT-U fusion. Premature ventricular contractions (PVCs; fourth and sixth beats from left) are noted by the green arrows. The second PVC, having followed the compensatory pause of the first PVC, initiated Torsade de Pointes [4, 5] conceivably due to an R-on-T phenomenon [6].
Three electrocardiograms (EKGs) are presented below with variable degrees of hypokalemia. In Figure A, the potassium level is 3.2 mmol/L. Prominent U waves are indicated by the blue arrows adjacent to the T wave, long known to be a sign of hypokalemia [1], causing prolongation of the QT interval due to QT-U fusion [2].
In Figure B, the potassium level is 1.7 mmol/L. Tall U waves, which exceed the T waves in height and fuse with them, are evident as indicated by the red arrows [3]. In Figure C, the potassium level is 2.4 mmol/L. Prolonged QT interval is indicated by the orange arrow probably due to QT-U fusion. Premature ventricular contractions (PVCs; fourth and sixth beats from left) are noted by the green arrows. The second PVC, having followed the compensatory pause of the first PVC, initiated Torsade de Pointes [4, 5] conceivably due to an R-on-T phenomenon [6].
References
Authors:
Mariam Riad, M.D.
Cardiology Fellow
University of South Alabama
Mobile, AL
Mustafeez Ur Rahman, M.D.
Cardiology Fellow
University of South Alabama
Mobile, AL
Alexis Parks, D.O.
Internal Medicine Resident
University of South Alabama
Mobile, AL
Douglas Williams, M.D.
Internal Medicine Resident
University of South Alabama
Mobile, AL
Nupur Shah, M.D.
Cardiology Fellow
University of South Alabama
Mobile, AL
Rajasekhar Mulyala, M.D.
Cardiology Fellow
University of South Alabama
Mobile, AL
G. Mustafa Awan, M.D.
Professor of Cardiology
University of South Alabama
Mobile, AL
Christopher Malozzi, D.O.
Associate Professor of Cardiology
University of South Alabama
Mobile, AL
Bassam Omar, M.D., Ph.D.
Professor of Cardiology
University of South Alabama
Mobile, AL
- Bernstein H, Alperin HL, Blum RL. Prominent U Waves of Hypokalemia. New Physician. 1963 Nov;12:Suppl A78-9.
- Omar HR. Hypokalemia-induced T-U fusion. Intern Emerg Med. 2012 Apr;7(2):193-4.
- Reddy GV, Schamroth L, Schamroth CL. Tall and peaked U waves in hypokalemia. Chest. 1987 Apr;91(4):605-7.
- Mathur P, Gupta SS, Sarasam R, Namana V. Dextrose, hypokalemia and torsade de pointes. QJM. 2017 Apr 1;110(4):249-250.
- Cranefield PF, Aronson RS. Torsade de pointes and other pause-induced ventricular tachycardias: the short-long-short sequence and early afterdepolarizations. Pacing Clin Electrophysiol. 1988 Jun;11(6 Pt 1):670-8.
- Oksuz F, Sensoy B, Sahan E, Sen F, Baser K, Cetin H, Unal S, Ozeke O, Topaloglu S, Aras D. The classical "R-on-T" phenomenon. Indian Heart J. 2015 Jul-Aug;67(4):392-4.
Authors:
Mariam Riad, M.D.
Cardiology Fellow
University of South Alabama
Mobile, AL
Mustafeez Ur Rahman, M.D.
Cardiology Fellow
University of South Alabama
Mobile, AL
Alexis Parks, D.O.
Internal Medicine Resident
University of South Alabama
Mobile, AL
Douglas Williams, M.D.
Internal Medicine Resident
University of South Alabama
Mobile, AL
Nupur Shah, M.D.
Cardiology Fellow
University of South Alabama
Mobile, AL
Rajasekhar Mulyala, M.D.
Cardiology Fellow
University of South Alabama
Mobile, AL
G. Mustafa Awan, M.D.
Professor of Cardiology
University of South Alabama
Mobile, AL
Christopher Malozzi, D.O.
Associate Professor of Cardiology
University of South Alabama
Mobile, AL
Bassam Omar, M.D., Ph.D.
Professor of Cardiology
University of South Alabama
Mobile, AL