From the Guidelines
Hyperkalemia causes progressive EKG changes that correlate with increasing potassium levels, with the earliest change being tall, peaked T waves (tenting) typically appearing when potassium exceeds 5.5 mEq/L, as noted in the most recent study 1. As levels rise further (>6.5 mEq/L), PR interval prolongation occurs, followed by P wave flattening and eventual disappearance. With severe hyperkalemia (>7 mEq/L), QRS complex widening develops as ventricular depolarization slows. In critical hyperkalemia (>8 mEq/L), the QRS complex continues to widen, eventually merging with the T wave to create a sine wave pattern, which often precedes ventricular fibrillation and asystole. These EKG changes reflect potassium's effect on cardiac cell membrane potentials, where excess extracellular potassium reduces the resting membrane potential difference, initially accelerating repolarization (causing tall T waves) but eventually slowing depolarization (widening QRS), as explained in 1. Recognizing these progressive changes is crucial for early intervention with calcium gluconate, insulin with glucose, beta-agonists, sodium bicarbonate, or dialysis in severe cases to prevent life-threatening arrhythmias. Some key points to consider include:
- The earliest EKG change in hyperkalemia is tall, peaked T waves (tenting) typically appearing when potassium exceeds 5.5 mEq/L 1.
- As potassium levels rise, PR interval prolongation, P wave flattening, and QRS complex widening occur, with severe hyperkalemia leading to a sine wave pattern and potentially life-threatening arrhythmias 1.
- Early intervention with calcium gluconate, insulin with glucose, beta-agonists, sodium bicarbonate, or dialysis is critical to prevent life-threatening arrhythmias in severe cases of hyperkalemia 1.
From the Research
EKG Changes Associated with Hyperkalemia
The electrocardiographic manifestations of hyperkalemia include:
- Peaked T-waves, particularly in the precordial leads 2
- Widening of the QRS-complex 2, 3
- Prolongation of the PR interval 2
- Flattening or absence of the P-wave 2
- A "sine-wave" appearance at severely elevated levels 2, 4
- Nonspecific repolarization abnormalities 5
- ST segment elevation simulating an acute myocardial infarction 6
- Brugada pattern on ECG, which can revert to normal after effective management of hyperkalemia 5
Severity of Hyperkalemia and EKG Changes
Severe hyperkalemia can lead to more pronounced EKG changes, including:
Importance of EKG Changes in Hyperkalemia
Recognizing these EKG changes is crucial for the rapid diagnosis and treatment of hyperkalemia, as timely intervention can be life-saving 2, 3.