Ventricular repolarization begins at the end of the QRS complex and lasts until the end of the T (or U) wave. In other words, the ECG depiction of ventricular repolarization includes the J point, ST segment, T wave, and/or the U wave. 

Conditions that alter ventricular repolarization commonly cause pathologic negative T waves. Pathologic ST segment changes tend to be rather specific. T wave changes not related to pathologic QRS complexes tend to be very nonspecific.