Which condition is associated with the "R on T" phenomenon?

Which condition is associated with the "R on T" phenomenon?

• A. Hypertension
• B. Hypokalemia
• C. Hypernatremia
• D. Bradycardia

Answer: (B)

The "R on T" phenomenon occurs when a premature ventricular contraction (PVC) lands on the T wave of the preceding beat. This can potentially lead to dangerous arrhythmias, such as ventricular tachycardia or ventricular fibrillation.

Hypokalemia, a condition characterized by low potassium levels in the blood, is strongly associated with this phenomenon. The reduction in potassium can lead to changes in cardiac myocyte excitability, which may result in the heart becoming more vulnerable to arrhythmias, including the occurrence of R on T. Low potassium levels affect the repolarization phase of the cardiac cycle, thus increasing the risk for arrhythmias when a PVC occurs on the T wave.

Understanding the relationship between hypokalemia and cardiac rhythm disturbances, particularly the R on T phenomenon, can help in identifying and managing patients at risk for serious ventricular arrhythmias.