Hyperkalemia

Electrolyte disorders are common and can be very dangerous. Potassium is one of the most important electrolytes in the body. Most potassium is intracellular and the small amounts of extracellular potassium are usually tightly regulated. Disorders of potassium can lead to critical arrhythmias if not detected rapidly.

Signs of Hyperkalemia

Hyperkalemia (high potassium) makes the heart less excitable. Classic signs of hyperkalemia include tall, peaked T waves. It may also cause a widened QRS, prolonged PR interval and loss of the P waves. If you think of the ECG trace as a length of string, it is a bit like someone is ‘pulling up’ on the T waves, dragging everything towards the T wave.

Do the ECG signs correlate to the serum K?

People are traditionally taught that the signs of hyperkalemia develop in a predictable fashion reflecting the degree of hyperkalemia. Under this model, early hyperkalemia (K+>5.5) causes peaked T waves, worsening hyperkalemia (>6.5) causes P and PR changes, while severe hyperkalemia (>7 ) causes wide QRS, conduction blocks, bradycardia and sine waves and extreme hyperkalemia (>9) causes cardiac arrest.ref However, any ECG changes are dangerous and need urgent treatment. Some patients have ECG changes that do not correlate with the potassium level and they are still at risk of arrest.ref

Hyperkalemia can mimic other dangerous conditions

Hyperkalemia can cause so many different ECG changes that Dr Amal Mattu refers to it as the “syphilis of electrocardiography”.ref In particular, hyperkalemia can cause dramatic ST segment changes so that it mimics a STEMI.ref It is also possible to have both hyperkalemia and an acute infarct! You should be on the lookout for hyperkalemia in patients with renal failure, potassium supplements, potassium-sparing diuretics, ACE inhibitors, or any patient with a new bradycardia or AV block.ref Constant vigilance is required!

References

ECG Library (67)

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In the ECGquest archives, this ECG has been tagged with: - Abdominal pain Chest pain 12-Lead Coved ST elevation Peaked T waves Tachycardia Wide QRS Sinus tachycardia Hyperkalemia Dr Smith's ECG Blog CC BY-NC
Do you recognize this ECG yet?

This ECG is from a man in his 30s who presented with chest pain and RUQ abdominal pain, on a background of type 1 diabetes. His BSL was high.

This ECG shows sinus tachycardia with a wide QRS, R in aVR, coved ST elevation and peaked T waves. The cause was hyperkalemia.

In the ECGquest archives, this ECG has been tagged with: - 12-Lead Wide QRS Hyperkalemia Dr Smith's ECG Blog CC BY-NC
A 60-something who has non-specific generalized malaise and is ill appearing.

This ECG is from a man in his 60s who presented with generalised malaise.

This ECG shows very wide complexes due to hyperkalemia (8.9).

In the ECGquest archives, this ECG has been tagged with: - Dyspnoea 12-Lead Peaked T waves Hyperkalemia Dr Smith's ECG Blog CC BY-NC
Patient with Dyspnea. You are handed a triage ECG interpreted as “normal” by the computer.

This ECG is from a dialysis patient who presented with dyspnoea.

This ECG shows subtly peaked T waves and flat ST segments. The cause was hyperkalemia (6.3).

In the ECGquest archives, this ECG has been tagged with: - Muscle pains 12-Lead Long QT Peaked T waves Hyperkalemia Hypocalcaemia Dr Smith's ECG Blog CC BY-NC
Patient with Dyspnea. You are handed a triage ECG interpreted as “normal” by the computer. ‘Baseline’ ECG

This ECG is from a dialysis patient who presented with diaphoresis and muscle cramps.

This ECG shows subtly peaked T waves and long ST segments causing a long QT interval. The cause was hyperkalemia (6.6) and hypocalcemia.

In the ECGquest archives, this ECG has been tagged with: - 12-Lead Absent P waves Peaked T waves Accelerated idioventricular rhythm Hyperkalemia EMergucate CC-BY-NC-SA
ECG of the Week Interpretation – March 20th 2019

This ECG is from a man in his 60s who presented with fever and delirium. He has a history of renal failure, T2DM and cognitive impairment.

This ECG shows accelerated idioventricular rhythm with peaked T waves due to hyperkalemia.

In the ECGquest archives, this ECG has been tagged with: - Cardiac arrest 12-Lead Bradycardia Irregular Peaked T waves Wide QRS Hyperkalemia Dr Smith's ECG Blog CC BY-NC
A patient with cardiac arrest, ROSC, and right bundle branch block (RBBB).

This ECG is from a patient who presented after a PEA arrest with ROSC after intubation and chest compressions.

This ECG shows irregular, slow, wide complex rhythm with peaked T waves due to hyperkalemia.

In the ECGquest archives, this ECG has been tagged with: - Hypotension 12-Lead Nonspecific baseline artefact Bradycardia Extra P waves Irregular Peaked T waves Wide QRS Second degree AV block Hyperkalemia Dr Smith's ECG Blog CC BY-NC
What will you do for this altered and bradycardic patient?

This ECG is from a woman in her 60s who presented from a nursing home with altered mental status, hypotension, hypoxia and bradycardia.

This ECG shows an irregular rhythm due to second degree AV block with wide QRS and peaked T waves. The cause was hyperkalemia.

In the ECGquest archives, this ECG has been tagged with: - Hypotension 12-Lead Pacemaker spikes Wide QRS Ventricular pacemaker Hyperkalemia Dr Smith's ECG Blog CC BY-NC
What will you do for this altered and bradycardic patient? Repeat ECG after transvenous pacemaker

This ECG is from a woman in her 60s who presented from a nursing home with altered mental status, hypotension, hypoxia and bradycardia. This was the repeat ECG after placement of a transvenous pacemaker.

This ECG shows a very wide ventricular paced rhythm with widespread excessive discordant ST elevation. The cause was hyperkalemia.

In the ECGquest archives, this ECG has been tagged with: - Chronic kidney disease 12-Lead Incorrect Machine Interpretation Flat ST segment Peaked T waves Hyperkalemia Dr Smith's ECG Blog CC BY-NC
I saw this computer “normal” ECG in a stack of ECGs I was reading

This ECG is from a woman of unknown age who presented with a clotted dialysis shunt.

This ECG shows peaked T waves and flattened ST segments caused by hyperkalemia.

In the ECGquest archives, this ECG has been tagged with: - Chronic kidney disease 12-Lead Flat ST segment Peaked T waves Hyperkalemia Dr Smith's ECG Blog CC BY-NC
What is the diagnosis?

This ECG is from a patient on dialysis who presented after a fall.

This ECG shows flattened ST segments and peaked T waves due to hyperkalemia.

In the ECGquest archives, this ECG has been tagged with: - 12-Lead Long PR Long QT Wide QRS Hyperkalemia Hypocalcaemia ECG of the Week CC-BY-NC-SA
ECG of the Week – 31st December 2018 – Interpretation

This ECG is from a woman in her 30s who presented with cramping following thyroid surgery.

This ECG shows prolonged QT due to long ST segment, no U waves, but also a prolonged QRS and PR. There was hypocalcemia, mild hyperkalemia and hypermagnesemia.

In the ECGquest archives, this ECG has been tagged with: - Loss of consciousness 12-Lead Long QT Peaked T waves Hyperkalemia Hypocalcaemia Dr Smith's ECG Blog CC BY-NC
Found comatose with prehospital ECG showing “bigeminal PVCs” and “Tachycardia at a rate of 156”

This ECG is from a patient with a history of diabetes who was found with a GCS of 4.

This ECG shows sinus rhythm with peaked T waves that were so narrow they were mistaken for separate QRS complexes. The cause was hyperkalemia due to acute renal failure.

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