Hyperkalemia induced high grade AV block

A 62-year-old female came with a history of giddiness and vomiting since last two days. Patient was a known case of diabetes mellitus and hypertension. Patient pulse during the time of admission was 24 beats per minute. Patient serum creatinine was 4, serum potassium was 6.6mq/dl. Patient ECG is shown below,

1 st ECG of the patient (Click on the ecg to enlarge it)

ECG is showing severe bradycardia with heart rate around 20 beats per minute, there is complete AV dissociation with atrial rate around 100 beats per minutes, QRS morphology is showing incomplete RBBB pattern, QT interval of 600 msec, corrected QTc of 346 msec, there are peaked, tall, tenting T wave of amplitude greater than QRS complex seen in lead V3-V6 so the ecg is suggestive of Complete heart block due to hyperkalemia. 

Patient was given hyperkalemia correction in the form of dextrose insulin drip, injection lasix, and calcium gluconate. Patient repeat ECG is shown below.

ECG of the patient

ECG is showing bradycardia with a heart rate around 50 beats per minute, there is a sudden loss of QRS complex for every 3rd P wave suggestive of 3.1 AV block suggestive of Mobitz type II AV block.

Repeat ECG of the patient after half an hour later of the second ECG 

ECG is showing normal sinus rhythm with tall tenting P wave in lead V2 only, with normal PR interval and RBBB block. Patient serum potassium during this time was 4.9.

Lets discuss ECG changes in hyperkalemia

In hyperkalemia earliest ECG changes seen is narrow and peaking T wave. There is a shortening of QT interval along with the widening of QRS duration. There is a decrease in the P wave amplitude along with prolongation of PR interval, which leads to second or third degree atrioventricular block. There will be a 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 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