POPULATION-SPECIFICCONCERNS Malissa Martin, EdD, ATC, CSCS, Report Editor

CommotioCordis in the Athletejane S, Kim • California State University, Long Beach

KEY POINT

(ommotio cordis (C() is a rare but deadlyconcussion of the heart, ( ( occurs as aresult of a blunt force to the chest wall,

•CC is often associated with youth sports, .nsuch as baseball and hockey, m

PPROXIMATELY 350,000 cases of suddencardiac death (SCD) occur in the United Stateseach year, ' The incidence of SCD during vari-ous types of athletic activity varies, Maron etal,2 estimated that 1 in 200,000 high schoolathletes die of SCD each year. Although theincidence of cardiac arrest among athletesis low, such an event demands an immedi-ate response. The purpose of this report is

to review the etiology ofcommotion cordis (CC)and to present possibleprevention strategies.

Case reports of CChave been documentedover the past 130 years,'Reports were often citedas SCD, with no struc-tural damage, during

Educated athletic trainers and therapists, performance of routinecoaches, and players can help prevent CC. .r tnanual labor. Theories

• about the etiology ofCC include alteration in

coronary blood flow and mechano-electricalfeedback,' Currently, the general consensusamong experts is that CC is primarily anelectrical event that results in instantaneousventricular fibrillation (VF),

SCD in athletes is most often attributableto a congenital or acquired cardiac disease(e,g,, hypertrophie cardiomyopathy) but mayalso result from a seemingly innocuous chestblow from body contact with an opponentor the impact of a projectile (i,e,, a baseball),A "cardiac concussion" can induce cardiacarrest in the absence of any premorbid car-diac disease or structural abnormality.

Although CC appears to be a randomevent, there have been a number of casesthat have had legal ramifications. In 1993,an Italian hockey player was charged withunintentional manslaughter when his oppo-nent died suddenly after having been hit inthe chest,•• The prevalence of CC in sport hasnot been clearly established, because manycases are not reported or are simply reportedas accidental deaths,' A National CommotioCordis Registry was established at the Min-neapolis Heart Institute Foundation in 1995to track cases of CC, with a focus on sportevents,^

Clinical Presentation

The creation of the National CommotioCordis Registry has provided a more accuratedescription of the circumstances of CC cases.Most cases have occurred during participa-tion in competitive youth baseball (Figure 1 ),but participation in hockey, lacrosse, soccer,Softball, and karate has also been reported,*The events usually involve a blow to the chestfrom a projectile thrown at normal velocity,with most victims being adolescent malesbetween 5 and 15 years of age who had nopreexisting heart condition (Table 1),'

Immediately after chest impact, collapseusually occurs, and resuscitation effortsare rarely successful. Cases have beenreported, however, that involved the victimbriefly continuing to perform an activity ina conscious state (e,g,, attempting to stand,speak, cry, walk, or throw a baseball) beforesubsequently collapsing in a state of cardiac

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Many ce cases occur during participation in competitive youthbaseball.

TABLE 1. GENERAL PROFILEAND STATISTICS OF C C VICTIMS® ''^

• Athletes participating in organized, competitive sports— 56-62 %

• Athletes participating in recreational sports — 22%

• Victims engaging in everyday activities (e.g. accidentalkick, remedy for hiccups, hit by a snowball, etc.) —22%

• Victims hit by projectile — 58%

• Instances involving body contact with another personor a stationary object — 42 %

• Athletes wearing chest protection — 28%

• Race: White — 80%

• Sex: male — 95%

• Mean age — 15 ± 9 years old (27% younger than 10;10% older than 25)

arrest.^ This suggests that VF may be tolerated for abrief period, before cardiac arrest occurs.^

Pathophysioloqy

The three major determinants of CC occurrence appearto be body location, timing, and force of impact.'̂ Car-diac arrest that is attributable to CC is precipitated byimpact directly over the heart. Although lesions are evi-dent in only a minority of cases, there may be bruisingon the left side of the sternum at the level of the nipples."

Maron et al." found that VF only occurs when anathlete is hit during the repolarization phase of the

heart cycle (diastole), specifically during the 15 to 30msec period preceding the T-wave peak."* Chest blowsreceived outside this defined interval can produce aheart block that is generally not lethal. Thus, the inci-dence of CC "near-miss" cases may be great.

The force of chest impact is a third factor that isdirectly related to the risk for cardiac arrest. An animalstudy of chest blows with baseballs demonstrated thatthe softest baseballs triggered VF in fewer impacts thanthose of intermediate hardness or the hardness of astandard baseball.'° Moreover, the velocity at whichbaseballs are thrown in the 15-30 msec window canaffect risk for cardiac arrest. Occurrence of VF in juve-nile swine was greatest at 40 mph, and the occurrencewas lower at velocities that were either less than orgreater than 40 mph. The high-velocity impacts mayhave created structural damage that precluded theoccurrence of VF" Thus, the risk of VF appears to belinked to a specific velocity of chest wall impact.

The susceptibility of young athletes to CC may beattributable to the amount and rate of chest wall com-pression that results from the external blow. A morecompliant chest wall transmits a greater amount ofimpact energy to the heart.'^ A defect in the function ofsodium channels, or irregular activation of potassium-ATP channels, may also play a role in sudden deaththat is attributable to C C

I

Prevention and Immediate Care

The survival rate of individuals who experience VF is15 96.̂ Athletic trainers and therapists (ATs) must rec-ognize and react to CC immediately. The recommenda-tions of the National Athletic Trainers' Association forprevention of CC include training athletic personnel inthe recognition of the signs and symptoms of CC andteaching athletes how to avoid being hit in the chest."

Utilization of protective athletic equipment mayseem to be an obvious method of prevention; however,while some experts have advocated the use of sport-specific chest protectors, it may not protect youngathletes from deadly blows.̂ Chest padding can shiftduring play, thereby allowing a ball to hit the unpro-tected chest wall, and protective gear has not beenfound to adequately dissipate the pressure generatedby chest wall impact to prevent CC.'̂ Further researchis needed to establish the characteristics of protectivegear that will provide optimum effectiveness.

Age-appropriate safety balls should be used todecrease incidence of CC in youth baseball. The

28 I JULY 2010 ATHLETIC THERAPY TODAY

adoption of safety balls in organized youth baseballis controversial, because some people feel that theyalter fundamental aspects of the game. Contrary tothis belief. Link et al.'°have suggested that safety ballsof intermediate hardness are indistinguishable fromthe standard baseball and should be used by olderage groups.

Training athletic personnel to recognize the mecha-nism of CC and to react immediately may increasethe chances for survival of athletes who experiencea low-impact blow to the chest. Immediate care forCC is the same as other cardiac emergencies: airwaymaintenance, chest compressions, and ventilation.'"Coaches and ATs, and perhaps even spectators, shouldbe trained in cardiopulmonary resuscitation (CPR),and automated external defibrillators (AEDs) shouldbe readily accessible. According to the American HeartAssociation, each minute of delay in delivering a defi-brillation shock to a cardiac arrest victim reduces thechances of survival by 10%.'^ Thus, rapid response isessential. Because the most common cause of deathin the 12 hours following a successful resuscitation isdysrhythmia, continuous ECG monitoring is essential.'*"

Common misconceptions about prevention andimmediate care include the ability to identify thoseat risk for CC through a preparticipation examina-tion and the appropriateness of delivering precordial"thumps" for resuscitation. Because CC can occur inhealthy athletes, a preparticipation exam has limitedvalue for prevention of cardiac arrest. The use of theprecordial thumps is controversial, particularly in chil-dren, because they can cause a regular heart rhythmto convert to VF'̂

Arrhythmia following CPR or automated externaldefibrillation may be controlled with medication orthrough management of risk factors. Athletes whosurvive CC should avoid substances that contribute toan irregular heartbeat, which include caffeine, tobacco,alcohol, and appetite suppressants. Because arrhyth-mia following CPR or automated external defibrilla-tion increases the risk of heart attack, cardiac arrest,and stroke, careful management of blood pressure,cholesterol level, body weight, and physical activityis important.'^

Summary

Cases of CC should be reported to the MinneapolisHeart Institute Foundation: www.suddendeathathletes.org. Although CC is uncommon, proper training for

its recognition and initiation of a prompt response isessential. If resuscitation is successful, a good long-term prognosis is possible. I

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2. Maron BJ, Epstein SE, Roberts WC. Causes of sudden death in com-petitive athletes.y/im CoUCardiol. 1986;7(1), 204-214,

3. Lateef F Commotio cordis; an underappreciated cause of suddendeath in athletes. Sports Med. 2000;30(4). 301-308.

4. Curfman GD. Fatal impact; concussion of the heart. N Englf Med.1998;338(25);184M843.

5. Maron BJ, DoererJJ, HaasTS, Link MS, Estes NAM III. C/iest Gear Ma;'not Protect Young Athletes From Deadly Blows. Available at; hltp.llwviw.americanheart.org/presenterjhtml7identifier = 3043387. AccessedJanuary 21, 2010.

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8. Link MS, Wang PJ, Pandian NG, Bharati S, UdelsonJE, Lee MY. Vec-chiotti MA, VanderBrink BA, Mirra G, Maron BJ, Estes NAM. 111. Anexperimental model of sudden death due to low energy chest wallimpact (commotio cordis). N Englf Med. 1998;J38(25); 1805-1811.

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10, Link MS, Maron BJ, Wang PJ, Pandian NG, VanderBrink BA, Estes NAMIII. Reduced risk of sudden death from chest wall blows (commotiocordis) with safety baseballs, Pediatri. 2002; /09(l): 873-877,

11, Link MS, Maron BJ, Wang PJ, VanderBrink BA, Zhu W, Estes NAM111, Upper and lower limits of vulnerability to sudden arrhythmicdeath with chest-wall impact (commotio cordis), J Am Coll Cardiol.2003;4/(l);99-104,

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13, National Athletic Trainers' Association, NATA official statement oncommotio cordis. Available at; http;//www,nata,org/statements/ofñcial/ASTFstmtCommotioCordisRevised091107(2).pdf, Accessed January18, 2010,

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15, U.S. Lacrosse Sports Science & Safety Committee, Position statementon commotio cordis. Available at: http://www,uslacrosse.org/safety/commotio_cordis_position.phtml. Accessed January 18, 2010,

16, Crown LA, Hawkins W, Commotio cordis: clinical implications of bluntcardiac trauma. Am Fam Physician. 1997;55(7):2467-2470,

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18, American Heart Association, Living with arrhythmias. Availableat; http;//www,americanheart.org/presenter.Jhtml?identiñer = 35.Accessed January 21, 2010,

Jane Kim is a graduate student at California State University, LongBeach. She is currently working toward a Master's degree in Kinesiol-ogy—Sports Medicine and Injury.

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