Heart Virus (心 臓 病 Shinzōbyō) is an extremely dangerous virus that can be lethal, even to a powerful warrior like Goku who must also die.
There is no exact name for this Heart virus, when a person is infected with the Heart Virus, the body will gradually become tired and in pain. The transformation into Super Saiyan causes side effects to accelerate the pain further.
The first manifestation is endurance, although Goku just flew not far away but sweat and fatigue showed up on his face. When the virus starts to penetrate deep into the body, the person will have a heart attack until death. Senzu cannot save either.
The only way to eradicate this virus is the medicine of the Future Trunks from future, and the future medicine is much more developed than it is now, so they can prevent it.
According to Piccolo, he speculated that the virus could be harmful to surrounding people, so he reminded Yamcha to take it as a precaution.
Timeline of Future Trunks
According to what Trunks said, Goku in his timeline died of Tim’s virus, not long after, Goku’s group died due to the attacks of Android 17 and 18.
Because Piccolo’s life and God were one, when Piccolo died, God died, the Angels died as well (this time Dende has not been taken up to take on this new position).
Main Time Line
Future Trunks used the time machine to return to the previous timeline to destroy Frieza’s father and son and give Goku the Heart Disease preventive medicine. But because in the process of training later Goku did not see any abnormal signs, so he did not bring and did not drink it.
The consequence of not taking preventive medicine is that in the battle with Android 19 and 20. Tien Shinhan has discovered Goku is losing his strength even though he has only been flying a short distance away, Goku also feels that his body is not right and turned into Super Saiyan and bombarded 19.
But the virus became more and more invasive and caused many side effects when transforming so Goku became tired and painful, he was defeated before Number 19 and Senzu couldn’t do anything at that time.
Luckily, Vegeta came to save Goku from danger, he was taken home by Yamcha and treated.
Not long after, Goku was fully recovered and joined his teammates against the Android & Cell.