commotio cordis

Ventricular fibrillation and sudden death triggered by a blunt, nonpenetrating, and often innocent-appearing unintentional blow to the chest without damage to the ribs, sternum, or heart (and in the absence of underlying cardiovascular disease) constitute an event known as commotio cordis.

When does commotio cordis occur?
About 55% of occurrences of commotio cordis have been reported in young competitive athletes (mostly those between 11 and 20 years of age) participating in a variety of organized amateur sports — typically baseball, softball, ice hockey, football, or lacrosse — who receive a blow to the chest that is usually (but not always) delivered by a projectile that is used to play the game.

How should suspected commotio cordis be treated?
A public health strategy that incorporates a plan for making automated external defibrillators (AEDs) widely available is likely to result in the survival of more young people in the event of commotio cordis. Indeed, AEDs have also effectively terminated ventricular fibrillation in animal models of commotio cordis. However, even under optimal conditions, an AED can fail to restore the heart to normal rhythm after commotio cordis. Both clinical studies and experimental studies suggest that precordial thumps are unreliable in terminating ventricular fibrillation caused by chest blows.

What location of a blow can precipitate commotio cordis?
To precipitate commotio cordis, the blow must be directly over the heart, particularly at or near the center of the cardiac silhouette. Precordial bruises representing the imprint of a blow are frequently evident in victims. There is no evidence in humans or in experimental models that blows sustained outside the precordium (e.g., the back, the flank, or the right side of the chest) cause sudden death.

At what part of the cardiac electrophysiological cycle must the blow occur?
The blow must occur within a narrow window of 10 to 20 msec on the upstroke of the T wave, just before its peak (accounting for only 1% of the cardiac cycle) — that is, the blow must occur during an electrically vulnerable period, when inhomogeneous dispersion of repolarization is greatest, creating a susceptible myocardial substrate for provoked ventricular fibrillation.

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Teaching topics from the New England Journal of Medicine
Vol. 362, No.10, March 11, 2010