What is r on t phenomenon?

The r-on-t phenomenon is a cardiac arrhythmia in which the ventricular depolarization (r-wave) occurs during the vulnerable period of the T wave on the electrocardiogram (ECG). This can trigger ventricular fibrillation, a potentially life-threatening rhythm disturbance. The vulnerable period of the T wave occurs during the refractory phase of ventricular repolarization when another electrical impulse can trigger ventricular arrhythmias. The r-on-t phenomenon is often seen in patients with long QT syndrome, ischemic heart disease, and electrolyte imbalances. Treatment may involve medication to manage underlying conditions and implantation of a pacemaker or defibrillator to prevent sudden cardiac death.