ECG changes in hyperkalemia

A 58 years old male who was admitted in intensive care unit developed acute onset palpitation along with giddiness.  Patient pulse was 150 beats per minutes, Blood pressure was 110/70 mmhg. Patient was on oral potassium supplement  to treat hypokalemia which he develop due to acute gastroenteritis. Patient serum potassium at the time of ecg was 6.0meq/dl.

ECG 1(Click on the ecg to enlarge it)

ECG is showing broad complex rhythm at rate around 170 beats per minutes, left axis deviation, QRS complex were of left bundle block morphology, there were monomorphic QRS complexes in lead  of there was no fusion beat or capture beat or fusion beat, also P wave were also not clearly visible. Possibility of both ventricular tachycardia or sine wave pattern due to hyperkalemia was kept. Patient was started on anti hyperkalemia measure and also injection amiodarone was given.

Patient ECG was repeated after 10 minutes

ECG was showing ST elevation in lead V3-V6. Patient cardiac Troponin came negative. ECG again done after five minutes. ECG is shown below.

Ecg is showing junctional rhythm with deep T wave inversion in lead V2-V5. P wave were not visible, QT interval was 420 msec, QTc 470 msec There were no other ST-T wave changes.

Patient was given anti hyperkalemia measure and he improved subsequently. His ecg  became normal. His echocardiography was normal and there was no regional wall motion abnormality.
His normal ecg  not available.
So the final diagnosis of the patient was hyperkalemia due to oral potassium supplement intake.

Lets discuss ECG changes in hyperkalemia

Reference-Braunwald 10th edition, Chapter no 12, Page no 147

In hyperkalemia earliest ecg changes seen is narrow and peaking T wave. There is shortening of QT interval along with widening of QRS duration. There is decrease in the P wave amplitude along with prolongation of PR interval, which lead to second or third degree atrioventricular block. There will be complete loss of P wave along with junctional escape rhythm or so called sinoventricular rhythm.
In the latter instance, sinus rhythm persists with conduction between the sinoatrial and atrioventricular nodes and occurs without producing an overt P wave. Moderate to severe hyperkalemia occasionally induces ST elevations in the right precordial leads (V1 and V2), simulating an ischemic current of injury or Brugada-type patterns. Very marked hyperkalemia leads to eventual asystole, sometimes preceded by a slow undulatory (or sine wave) ventricular flutter like pattern.

Thank you

Praveen Gupta