Cardio Case Challenge: A 17-Year-Old in Cardiac Arrest After Collision Playing Sports

Jansen Tiongson, MD; Lisa Chan, MD


December 16, 2022

A review of data from the US Commotio Cordis Registry (USCCR), in Minneapolis, Minnesota revealed that most cases were caused by a blow to the chest from an object used during an organized youth sporting event.[2] A baseball accounted for 53 of the cases, with a softball and a hockey puck the next most frequent, at 14 and 10 cases, respectively. Other documented sporting cases have been caused by blows delivered by body parts, such as an elbow, knee, foot, or fist hitting the anterior chest wall (5-6 cases of each).

Daily activities, including parent-child discipline (5 cases), and even a fall from monkey bars (1 case), can also lead to commotio cordis. Regardless of the mechanism, impacts resulting in commotio cordis are typically of low energy and velocity.[1,4] The victim may collapse immediately after the blow, but in as many as 50% of cases, a short delay occurs between the impact and collapse.

In 1930, George Schlomka was the first to describe the factors that can lead to arrhythmia after a moderate precordial impact. He believed that the force, location, and type of object causing the impact determined the type of injury and the subsequent risk for arrhythmia.[2] The force transmitted to the heart is directly related to the hardness of the striking object. Madias and colleagues[4] reported that the threshold speed of impact at which a standard baseball can cause ventricular fibrillation is between 25 and 30 miles per hour. However, when the speed is over 50 miles per hour, the likelihood of ventricular fibrillation actually decreases, although the possibility of myocardial contusion becomes greater. Furthermore, the authors stated that the impact must be directly over the heart near or just to the left of the sternum in order to instigate ventricular fibrillation. Impact on the center of the heart induced ventricular fibrillation in 30% of reported cases, compared with 13% and 4% at the left ventricular base and apex, respectively.[4]

The use of a standard baseball leads to the incidence rate reported above, but if the core of the ball is softer, then the rate for ventricular fibrillation drops. Link and colleagues[5] reported that changes to the cores of baseballs to make them softer led to a decrease in the rate of ventricular fibrillation with commotio cordis from 70% to 19%. As such, the use of safety baseballs with rubber cores of different degrees of hardness has been advocated to reduce the risk for such traumatic injury in young athletes.[3,5]

Not all impacts to the anterior chest lead to the ventricular fibrillation observed in commotio cordis. The impact must be delivered 10-30 milliseconds before the peak of the T wave in the cardiac cycle (Figure 5) in order to induce ventricular fibrillation.

Figure 5.

Induction is probably secondary to the activation of potassium-carrying ion channels via mechanoelectric coupling. The activation of these ion channels generates an inward current, thus locally augmenting repolarization and resulting in premature ventricular depolarization and the initiation of unstable ventricular arrhythmias. If impact occurs during other portions of the cardiac cycle, different conduction disturbances, such as heart block, bundle branch block, or transient ST segment elevation, may be induced.[2,4,5]


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