What is the most likely cause of collapse in a baseball player struck in the chest?

Collapse in a baseball player struck in the chest is most likely caused by ventricular fibrillation. This occurs when an impact at a critical moment in the cardiac cycle leads to a disruption in the heart's electrical rhythm, resulting in chaotic and ineffective contractions.

In cases of blunt force trauma to the chest, such as being hit by a baseball, the heart can be affected if the impact occurs during the T wave of the cardiac cycle. This timing can precipitate ventricular fibrillation, a condition that rapidly leads to the loss of effective circulation and can result in sudden cardiac arrest.

The likelihood of ventricular fibrillation as the cause of collapse is further supported by the fact that the heart is especially vulnerable to disruptions in its rhythm during this moment. Other causes, such as rupture of the aorta, while serious, typically involve other types of trauma and would present with different symptoms and mechanisms of collapse. Myocardial contusion, while a possible outcome of blunt trauma, may not lead to immediate collapse as effectively as ventricular fibrillation. Shearing of the vena cava is a severe condition that usually relates to major trauma, and less common in sports-related impacts.

Understanding the mechanism of how chest impacts can affect heart rhythm is crucial in recognizing emergency situations in sports and