How does ventricular tachycardia kill you?

Mechanism below:: When VT occurs at a fast enough rate, there is inadequate time for blood to fill the ventricle during each cycle, cardiac output falls, and blood pressure falls. Rate is the key variable. As tissue perfusion fails, acidosis, hypoxemia (low oxygen) and hyperkalemia (high potassium) result which leads to further deterioration in rhythm, ie, ventricular fibrillation and death.

Ventricular: Not all are dangerous. But some are. In these cases your heart may go into ventricular fibrillation and your heart stops popping blood to your body. Or, in some rare cases, especially you have an additional problem such as weak heart muscle, ventricular tachycardia can kill you. Electrophysiology docs like my self can differentiate ones with risk from none risky ones.