From the Guidelines
Hyperkalemia causes characteristic EKG changes that progress with increasing potassium levels, with the earliest change being peaked T waves, followed by PR interval prolongation, P wave flattening, QRS widening, and eventually a sine wave pattern, as described in the 2010 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care 1. The EKG changes associated with hyperkalemia are a result of the effect of potassium on cardiac cell membrane potential, causing faster repolarization initially and then slowing depolarization.
- The earliest EKG change in hyperkalemia is the presence of peaked T waves (tenting) on the electrocardiogram (ECG), which can occur when serum potassium rises above 5.5 mmol/L.
- As serum potassium levels continue to rise, the ECG may progressively develop:
- Flattened or absent P waves
- A prolonged PR interval
- Widened QRS complex
- Deepened S waves
- Merging of S and T waves
- If hyperkalemia is left untreated, a sine-wave pattern, idioventricular rhythms, and asystolic cardiac arrest may develop, as noted in the study published in Circulation 1. Treatment of hyperkalemia-induced EKG changes should be initiated promptly, with calcium gluconate, insulin, and glucose being the first line of treatment, as they can help stabilize cardiac membranes and shift potassium intracellularly 1.
- Additional treatments, such as sodium bicarbonate and beta-agonists like albuterol, may also be used to help manage hyperkalemia.
- Definitive treatment requires potassium removal through diuretics, potassium binders, or dialysis in severe cases, as recommended in the guidelines 1.
From the Research
EKG Changes in Hyperkalemia
- Hyperkalemia can cause various cardiac dysrhythmias, which may result in cardiac arrest and death 2
- EKG changes in hyperkalemia can include:
- Tenting T waves
- Disturbance of intraventricular conduction
- Deformed wide QRS complexes
- Atrial asystole 3
- The most common EKG changes associated with hyperkalemia are:
- Initial high T waves and shortened intervals
- Prolongation of conduction and lethal dysrhythmias as the serum potassium level rises 4
- It is important to note that absent or atypical EKG changes do not exclude the necessity for immediate intervention in hyperkalemia 5
Clinical Considerations
- Hyperkalemia is a life-threatening electrolyte imbalance that may lead to fatal arrhythmias 6
- Severe hyperkalemia can cause fatal rhythm disturbance and terminal heart arrest 3
- The most frequent causes of hyperkalemia in elderly patients are iatrogenic medication-related etiology due to associated polymorbidity, polypharmacy, and reduced reserve metabolic capacity 3
- Potassium sparing drug therapy in older persons requires more frequent monitoring especially when drugs or their doses are changed, or during concomitant acute illness 3
Treatment and Prevention
- Treatment of hyperkalemia involves shifting potassium intracellularly and eliminating it through renal and gastrointestinal routes 6
- Management includes measures to "stabilize" cardiac membranes, to shift K+ from extracellular to intracellular stores, and to promote K+ excretion 2
- Calcium gluconate 10% dosed 10 mL intravenously should be provided for membrane stabilization, unless the patient is in cardiac arrest, in which case 10 mL calcium chloride is warranted 2