What is the effect of hyperkalemia on an ECG?

• A. Flatter T waves and narrower QRS complexes
• B. Peaked T waves, widening of QRS complexes
• C. Bradycardia and ST segment elevation
• D. Normal T waves and a regular rhythm

Answer: (B)

Hyperkalemia, which is an elevated level of potassium in the blood, has specific and recognizable effects on the electrocardiogram (ECG) that are key to understanding the condition. The classic presentation on an ECG due to hyperkalemia includes peaked T waves and a widening of the QRS complexes.

Peaked T waves appear as tall and narrow spikes following the QRS complex, indicating that the myocardial repolarization is being affected by the increased potassium levels. This change is one of the earliest signs of hyperkalemia on an ECG. As the potassium levels continue to rise, the QRS complex starts to widen, which signifies that the conduction through the ventricles is being altered. The widening of the QRS is concerning as it can lead to more severe arrhythmias and conditions such as ventricular tachycardia or even ventricular fibrillation if left unmanaged.

These ECG changes are critical markers that clinicians use as indicators of hyperkalemia, making the understanding of these visual characteristics essential for timely diagnosis and treatment.