Commotio cordis is an extremely rare heart problem where a patient's heart goes into fibrillation as a result of a blow to the chest at precisely the wrong moment. The fibrillation will cause the patient to lose consciousness, and she can die if not provided with prompt treatment. Doctors most commonly observe commotio cordis at youth sporting events, as athletes are more at risk of blows to the chest, and young athletes have flexible chest walls, making it possible to interrupt heart rhythms with a blow that might not be dangerous for an adult. Sometimes collisions with steering wheels in car accidents can cause similar damage.
For commotio cordis to occur, the impact has to occur in a very small area of the chest, where it can interrupt heart rhythms by disrupting the heart. It also must occur during the repolarization phase, as the heart is in transition from pumping blood out to receiving deoxygenated blood from the rest of the body. The specific timing and placement needed for this to happen make it very rare; many athletes experience blows to the chest with no ill effects because they happen at an acceptable time, or on a safe area of the chest.
It is possible to recover from fibrillation if provided with prompt medical treatment. Any time someone collapses and appears not to have a pulse, cardiopulmonary resuscitation should be provided. If an automated external defibrillator is available, this can be used to check the heart rhythm and prepare a shock to force the heart back into action. Many sports fields have such devices so bystanders can provide emergency medical assistance. Paramedics can also use their own equipment on arrival, but with disruptions to the heart rhythm, every second counts, and anyone present should not wait for first responders to show up.
After commotio cordis, a patient who receives treatment and recovers his normal heart rhythm should experience no ill effects, although his chest may be bruised. A doctor may recommend an evaluation if there are any concerns, and it is important to be aware that this condition is not the fault of a preexisting heart problem or an indicator that the patient will have heart problems in the future.
In the event that a patient does not receive treatment for commotio cordis in time, she will die. Athletes, coaches, and family members can address the risks of this rare accident by wearing chest protectors in games, being conscientious about avoiding blows to the chest, and responding promptly if someone falls on the field and appears to be in distress.