Hypokalemia electrocardiogram: Difference between revisions

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The most notable EKG findings in [[hypokalemia]] are due to the delayed ventricular repolarization, manifesting as (QT-U) with prominent [[U waves]].  The EKG changes of hypokalemia are commonly seen at potassium levels < 3 meq/Li. 90% of the patients with potassium levels <2.7 meq/L have abnormal ECG findings.
The most notable EKG findings in [[hypokalemia]] are due to the delayed ventricular repolarization, manifesting as (QT-U) with prominent [[U waves]].  The EKG changes of hypokalemia are commonly seen at potassium levels < 3 meq/Li. 90% of the patients with potassium levels <2.7 meq/L have abnormal ECG findings.


==Diagnosis==
==Electrocardiogram==
===ECG changes===
===ECG Changes===
# [[ST segment depression]], decreased [[T wave]] amplitude, prominent [[U waves]]
# [[ST segment depression]], decreased [[T wave]] amplitude, and prominent [[U waves]]:
#* seen in 78% of patients with a K < 2.7 meq
#* Seen in 78% of patients with a K < 2.7 meq
#* seen in 35% of patients with a K > 2.7 and < 3.0
#* Seen in 35% of patients with a K > 2.7 and < 3.0
#* seen in 10% of patients with a K > 3.0 and < 3.5
#* Seen in 10% of patients with a K > 3.0 and < 3.5
#* [[U waves]] are also prominent in [[bradycardia]] and [[LVH]]
#* [[U waves]] are also prominent in [[bradycardia]] and [[LVH]]
# [[Prolongation of the QRS]] duration
# [[Prolongation of the QRS]] duration
#* uncommon except in severe hyperkalemia
#* Uncommon except in severe hyperkalemia
# Increase in the amplitude and duration of the [[P-wave]]
# Increase in the amplitude and duration of the [[P-wave]]
# [[Cardiac arrhythmias]] and [[AV block]]
# [[Cardiac arrhythmias]] and [[AV block]]
# '''Contrary to popular belief there is not prolongation of the QTc''', this is artifactually prolonged due to the U wave. In some cases there is fusion of the T and U waves making interpretation impossible.
# Contrary to popular belief there is not prolongation of the QTc, this is artifactually prolonged due to the U wave. In some cases there is fusion of the T and U waves making interpretation impossible.
# Ventricular ectopy
#* [[Premature ventricular complex]]
#* [[Ventricular tachycardia]]
#* [[Ventricular fibrillation]]


===ECG Examples===
===ECG Examples===
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==Treatment==
The EKG changes of hypokalemia are rapidly reversible with potassium repletion.
The EKG changes of hypokalemia are rapidly reversible with potassium repletion.



Latest revision as of 20:36, 21 October 2014

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor-In-Chief: Cafer Zorkun, M.D., Ph.D. [2]; Assistant Editor(s)-In-Chief: Jack Khouri

Overview

The most notable EKG findings in hypokalemia are due to the delayed ventricular repolarization, manifesting as (QT-U) with prominent U waves. The EKG changes of hypokalemia are commonly seen at potassium levels < 3 meq/Li. 90% of the patients with potassium levels <2.7 meq/L have abnormal ECG findings.

Electrocardiogram

ECG Changes

  1. ST segment depression, decreased T wave amplitude, and prominent U waves:
    • Seen in 78% of patients with a K < 2.7 meq
    • Seen in 35% of patients with a K > 2.7 and < 3.0
    • Seen in 10% of patients with a K > 3.0 and < 3.5
    • U waves are also prominent in bradycardia and LVH
  2. Prolongation of the QRS duration
    • Uncommon except in severe hyperkalemia
  3. Increase in the amplitude and duration of the P-wave
  4. Cardiac arrhythmias and AV block
  5. Contrary to popular belief there is not prolongation of the QTc, this is artifactually prolonged due to the U wave. In some cases there is fusion of the T and U waves making interpretation impossible.
  6. Ventricular ectopy

ECG Examples

Shown below is an example of hypokalemia with long QT interval, ST segment depression, low T waves amplitude and TU wave fusion.


Shown below is an example of hypokalemia with Left Ventricular Hypertrophy.


The EKG below demonstrates characteristics of hypokalemia including: T wave inversions and U waves circled in red; flattening of ST segment and prolonged Q- U interval as circled in green.


The EKG changes of hypokalemia are rapidly reversible with potassium repletion.

References


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