The amount of blood pumped by the left ventricle of the heart during one heartbeat is called?

It is known as stroke volume.

Stroke volume (SV) is the volume of blood pumped by the right/left ventricle of the heart in one contraction.

The stroke volume is not all of the blood contained in the left ventricle. The heart does not pump all the blood out of the ventricle. Normally, only about two-thirds of the blood in the ventricle is put out with each beat. What blood is actually pumped from the left ventricle is the stroke volume and it, together with the heart rate, determines the cardiac output.