The accident occurred last month in Nghe An Province when the boy was put in front of the steering of a car driven by a relative.
When the car crashed into a wall, his chest hit the steering wheel. It remains unclear how the accident happened.
He was taken to Nghe An Maternity - Pediatric Hospital under a life-threatening condition.
Echocardiographic results showed acute cardiac tamponade, rupture of the right ventricular wall, and pericardial effusion.
Doctors on Friday confirmed the child had suffered severe heart injury and a concussion to the left lung, which required immediate surgery.
When the surgical team opened his chest, the heart had already ceased beating. They reported an abundant amount of hematoma in the pericardial cavity.
Surgeons quickly opened the pericardium and drained the hematoma and simultaneously, manually squeezed and stimulated the baby's heart back into action.
After a minute, his heartbeat had returned to normal.
The surgical team then put the patient on ECMO (extracorporeal membrane oxygenation) and noted the heart had its right atrium torn by around one centimeter.
They sutured the rupture, drained the lungs, and contained bleeding in the pericardium, and mediastinum. After surgery, the patient gradually regained consciousness and stable function of the cardiovascular and respiratory systems.
Now in stable condition, he remains in recovery.
His condition is complex and has a very high mortality rate, doctors warned.
It was recommended adults absolutely refrain from letting their children sit on their laps while driving a car, and that a child seat and safety belt is necessary.