Commotio cordis generally results in what arrhythmia?

Commotio cordis is a condition that occurs when a blunt force impact to the chest happens during a specific window of the cardiac cycle, typically leading to a disruption of the heart's electrical activity. The most common and significant arrhythmia associated with commotio cordis is ventricular fibrillation.

Ventricular fibrillation is characterized by rapid, erratic electrical impulses in the ventricles, causing them to quiver ineffectively instead of contracting in a coordinated manner. This results in loss of effective blood circulation and can lead to sudden cardiac arrest if not quickly addressed with defibrillation. The timing of the impact is crucial; if it occurs just before the T-wave of the ECG, it can precipitate this life-threatening arrhythmia.

Understanding the underlying mechanism helps clarify why ventricular fibrillation is specifically associated with commotio cordis rather than other arrhythmias, which may not arise from the same type of mechanical insult to the heart. For example, tachycardia and bradycardia involve higher or lower heart rates, respectively, but do not typically stem from the acute circumstances presented in commotio cordis. Atrial fibrillation, which is an irregular and often rapid heart rhythm, also does not correlate with