Sudden Cardiac Arrest: Commotio Cordis

This condition occurs primarily in young males, with the highest incidence in sports such as baseball and hockey; however, it can be seen in sports such as softball, lacrosse, and soccer as well. It may occur in any sport with male or female participants whereby a blow, via contact with another player, or via the ball/puck exerts a sudden impact to the precordial region.

Commotio cordis was 1st described in 1763, and at least 190 cases have been documented in the U.S. alone.

It is the 2nd most common cause of sudden cardiac death in athletes younger than 35.

Greater recognition of this condition has led to improved reporting of it.

The prevalence is higher in competitive sports, with nearly half of the cases occurring during competitive sports. The mean age is 15.6 ± 6.5 yrs, with young males 4–18 at greatest risk (1).

Youth baseball accounts for most of the cases.

Participation in competitive sports known to have a greater risk of CC.

Harder projectiles used in certain sports are more likely to cause CC, with use of standard baseballs and pitches with speeds between 30 and 50 mph carrying the highest incidence of developing the insult.

Velocities above and below this range did not seem to carry the same risk.

Use of protective equipment has not been demonstrated to offer adequate protection from CC.

The U.S. Consumer Product Safety Commission recommends use of softer “safety baseballs” to reduce the risk of soft tissue trauma (3). These “safety baseballs” reduced the risk of onset of VF after precordial impact in a swine model study, and there is a linear correlation between CC events and the relative hardness of a baseball (4)[B]. However, safety baseballs have not been proven to eliminate risk of CC.

Doerer et al. and Weinstock et al. have demonstrated that chest protectors (commonly worn by catchers) in baseball did not prove to be effective in eliminating cases of CC (5). Only 13% of victims who were wearing chest protectors survived a CC event. It is theorized that malpositioning of equipment (when the athlete moves or raises his hands) may contribute to this failure. A swine model by Link et al. revealed that commercially available chest protectors did not prevent CC (6).

Changes in coaching techniques to eliminate chest blocking are theorized to potentially reduce CC events.

Public health measures, such as parents/coaches learning CPR, and the increased availability and use of automated external defibrillator (AED) may provide the biggest impact on improving CC outcomes, but cannot necessarily prevent onset of CC due to the pathophysiology of condition.

Impact to the precordium during the vulnerable period of the repolarization upslope of the T-wave (10–30 ms before the T-wave peak) may lead to VF. VF is the most common initial rhythm in CC.

A study by Link et al. demonstrated that low energy impact, directly over the heart, specifically over the center of the left ventricle (LV), carries the highest risk. Blows at noncardiac sites in this study did not generate VF (7).

The role of projectile speed and projectile hardness has been discussed. The ideal projectile speed and hardness create an ideal energy transfer that potentiates this often-lethal condition.

Causative theories on predisposition to VF/CC include rapid rises in LV pressures to forces between 250 and 450 mm Hg that may potentiate the associated arrhythmia. Stretch channels may be activated due to associated myocardial stretch with impact, and potassium adenosine triphosphate channel activation has been implicated (8).

Critical mass of projectile leading to higher velocity impacts tends to lead to myocardial damage as opposed to myocardial activation.

Sympathetic activation occurring during sports participation may increase the likelihood of CC, but this has not been substantiated in research studies.

Contusio cordis

Myocardial contusion with tissue damage

Rule out other causes of SCD causing arrhythmia such as hypertrophic cardiomyopathy (HCM).

There are no specific labs/imaging tests to aid in diagnosis.

CC is a diagnosis made based on witnessed precordial blow and confirmed by AED recognition of subsequent arrhythmia.

HCM

Long QT syndrome

Wolff-Parkinson-White syndrome

Arrhythmogenic right ventricle dysplasia

Brugada syndrome

Dilated cardiomyopathy

Marfan syndrome

Aortic valve stenosis

Mitral valve prolapse

Coronary artery disease

Myositis

Asthma

Heat stroke

Drug abuse (1)[C]

An individual athlete's susceptibility to CC should be considered in any return to play decisions regarding contact sports.

Decisions are made on a case-by-case basis, with consideration given to residual cardiac deficit, neurologic deficit, or other morbidity. Cardiology consultation should be involved in these decisions (4)[C].

Maron et al. demonstrated that 71% of CC survivors achieved complete physical recovery (10).

CC is a condition that carries a grave prognosis. Despite use of ACLS protocols, the condition is often lethal. Immediate recognition of condition and use of AED to abolish cardiac arrhythmia may allow improved survival and decreased subsequent morbidity.

As the availability and use of AEDs during athletic participation occurs, their effectiveness may be further measured in future studies.