Needles that hit the heart directly did exist in the 1980s. They are cardiotonic needles. A longer needle goes straight into the heart and is used for first aid. In the 1990s, they switched to intravenous needles, which were more effective and safer.

The possibility in the movie is that the virus will enter the heart and cause infection, and an injection will be injected into the heart for a period of time to prevent infection.