J wave

A J wave is a small, early upward bump seen on an electrocardiogram (ECG) that occurs at the start of the heart's repolarization phase, particularly in certain arrhythmias. It appears during the transition between the depolarization and repolarization of the heart's ventricles. While sometimes harmless, prominent J waves can be associated with increased risk of abnormal heart rhythms, especially in people with underlying heart conditions or specific syndromes. Understanding and identifying J waves helps doctors assess heart health and potential arrhythmia risks.