Emergency Medical Technician (EMT) Intermediate Practice Exam

What characterizes commotio cordis?

1. Heart failure due to cardiac muscle damage

2. Immediate cardiac arrest during a critical moment of heart's repolarization

3. Severe arrhythmias caused by blunt chest trauma

4. Cardiac arrest due to drug overdose

The correct answer is: Immediate cardiac arrest during a critical moment of heart's repolarization

Commotio cordis is a condition characterized by immediate cardiac arrest that occurs during a critical moment of the heart's repolarization phase, particularly during the vulnerability period of the cardiac cycle, specifically the T-wave. This event typically follows a blunt, non-penetrating impact to the chest, such as being struck by a baseball or hockey puck. The force applied at the precise moment disrupts the electrical activity of the heart, leading to an abnormal rhythm and resulting in sudden cardiac arrest. The timing of the blow is crucial, as it must coincide with the T-wave in the cardiac cycle, which is when the heart is particularly susceptible to disturbances in its electrical activity. Thus, the direct relationship between the timing of the impact and the heart's electrical cycle is essential to understanding why immediate cardiac arrest occurs in commotio cordis cases. The other choices describe conditions that do not align with the specific mechanism of commotio cordis. For instance, heart failure due to cardiac muscle damage involves a different pathological process and is usually a chronic condition rather than an acute event triggered by trauma. Severe arrhythmias caused by blunt chest trauma are broader and may arise in various circumstances but do not specifically narrow down to the precise electrical event mandated by comm