Commotio cordis
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[[Image:Heart-thorax-gray.gif|thumb|300px|right|Human adult thorax, showing the outline of the heart (in red). The sensitive zone for mechanical induction of heart rhythm disturbances lies between the 2nd and the 4th ribs, to the left of the sternum]]
'''Commotio cordis''' (from [[Latin]] ''commotion of the heart'' - a functional effect of mechanical stimulation in the absence of structural damage, as opposed to [[myocardial contusion]] which involves tissue damage) is a sudden disturbance of [[heart rhythm]] observed mostly in young people during participation in [[sport]]s. It occurs as the result of a blunt, non-penetrating [[impact]] to the [[precordium|precordial region]], often caused by impact of a [[ball]], a [[Bat (disambiguation)|bat]] or other projectile. The impact is transmitted to the heart muscle, and depending on the precise timing in relation to the [[cardiac cycle]], it may affect the heart's electrical activity, causing an [[arrhythmia]], such as an [[ectopic beat]], [[ventricular tachycardia]] or [[ventricular fibrillation]]. Pre-existing conditions, such as undetected electrical or structural abnormalities in the [[heart]] of these individuals, have been speculated to render individuals more vulnerable, but this view is not currently corroborated by hard evidence. The phenomenon was confirmed experimentally in the 1930s, with research in anaesthetized [[rabbit]]s, [[cat]]s and [[dog]]s.<ref>Schlomka G. Commotio cordis und ihre Folgen. Die Einwirkung stumpfer Brustwandtraumen auf das Herz. Ergebnisse der inneren Medizin und Kinderheilkunde. 1934;47: 1-91.</ref>
==Incidence==
''Commotio cordis'' is a very rare event, but nonetheless is often considered when an athlete presents with sudden cardiac death. Some of the sports which have a risk for this cause of trauma are [[baseball]], [[football (soccer)|soccer]], [[ice hockey]], [[polo]], [[Rugby football|rugby]], [[cricket]], [[softball]], [[pelota]], [[fencing]], [[lacrosse]], [[boxing]], [[karate]], [[kung fu]] and other [[martial arts]]. [[Child]]ren are especially vulnerable, possibly due to the mechanical properties of their [[thorax|thoracic skeleton]]. The [[United States|USA]] ''Commotio Cordis Registry'' had more than 130 cases recorded by September 2001, with most of the cases occurring in [[Little League]] baseball, lacrosse and softball. {{Fact|date=June 2007}} The real number of cases may be much larger. {{Fact|date=June 2007}}
==Other situations==
''Commotio cordis'' may occur also in other situations, such as in children who are punished with blows over the precordium, cases of [[torture]], frontal collisions of [[motor vehicle]]s (the impact of the steering wheel against the thorax, although this has decreased substantially with the use of [[safety belt]]s and [[air bag]]s).
Cases of ''commotio cordis'' have been recorded in people who were shot by [[firearm]]s over the precordium and were using [[body armour]],<ref>Cannon L. Behind armour blunt trauma--an emerging problem. ''J R Army Med Corps.'' 2001 Feb;147(1):87-96. Review. PMID 11307682 </ref> thus stopping the bullet but causing a mechanical impact to the thorax (the so-called Behind Armour Blunt Trauma or BABT); or after being hit by less-lethal [[crowd control]] firearm shots using [[rubber bullet]]s or [[plastic bullet]]s.<ref>Hiss J, Hellman FN, Kahana T. Rubber and plastic ammunition lethal injuries: the Israeli experience. ''Med Sci Law.'' 1997 Apr;37(2):139-44. PMID 9149508</ref>
In contrast, the [[precordial thump]] (hard blows given over the precordium with a closed fist in order to revert [[cardiac arrest]]) is a sanctioned procedure for emergency resuscitation by trained health professionals witnessing a ''monitored'' arrest when no equipment is at hand, endorsed by the latest guidelines of the [http://www.erc.edu/index.php/ilcor/en/ International Liaison Committee on Resuscitation]. It has been discussed controversially, as - in particular in severe hypoxia - it may cause the opposite effect (i.e., a worsening of rhythm - ''commotio cordis''). In a normal adult, the energy range involved in the precordial thump is 5-10 times below that associated with commotio cordis.<ref name="Kohl2005">Kohl P, Sachs F & Franz M (eds): ''Cardiac Mechano-Electric Feedback and Arrhythmias: from Pipette to Patient''. Elsevier (Saunders), Philadelphia 2005.</ref>
==Mechanism of injury==
[[Image:Commotio-cordis-ecg.jpg|right|framed|Electrocardiogram schematic tracing, showing the period of vulnerability to stretch-induced ventricular fibrillation which occurs in commotio cordis]]
The following factors influence the chance of ''commotio cordis'':
* Direction of impact over the precordium (precise area, angle of impact)
* Total applied energy (area of impact versus energy, i.e., the mass of the projectile multiplied half the square of its velocity)
* Impact occurring within a specific 10-30 millisecond portion of the cardiac cycle. This period occurs in the ascending phase of the T wave, when the ventricular myocardium is repolarizing, moving from [[systole]] to [[diastole]] (relaxation).
The small window of vulnerability explains why it is a rare event. Considering that the total cardiac cycle has a duration of 1000 milliseconds (for a base cardiac frequency of 60 beats per minute), the probability of a mechanical trauma within the window of vulnerability is 1 to 3% only. That explains also why the heart becomes ''more'' vulnerable when it is physically strained by sports activities:
# The increase in heart rate (exercise [[tachycardia]]) may double the probability above (e.g., with 120 beats per minute the cardiac cycle shortens to 500 milliseconds without fundamentally altering the windows of vulnerability size);
# Relative exercise-induced [[Hypoxia (medical)|hypoxia]] and acceleration of the excito-conductive system of the heart make it more susceptible to stretch-induced ventricular fibrillation.
The [[cell (biology)|cellular]] mechanisms of ''commotio cordis'' are still poorly understood, but probably related to the activation of mechano-sensitive proteins, [[ion channels]].
It is estimated that impact energies of at least 50 [[joule]]s are required to cause cardiac arrest, when applied in the right time and spot of the precordium of an adult. Impacts of up to 130 joules have already been measured with [[hockey puck]]s and lacrosse balls, 450 joules in karate punches and an incredible 1028 joules in boxer [[Rocky Marciano]]'s punch.<ref name="titlescience.ca View question #821">{{cite web |url=http://www.science.ca/askascientist/viewquestion.php?qID=821 |title=science.ca View question #821 |accessdate=2008-02-23 |format= |work=}}</ref> The 50 joules threshold, however, can be considerably lowered when the victim's heart is under [[ischemia|ischemic]] conditions, such as in [[coronary artery]] insufficiency.<ref name="Kohl2005" />
There is also an upper limit of impact energy applied to the heart; too much energy will create structural damage to the heart muscle as well as causing electrical upset. This condition is referred to as [[contuiso cordis|''contusio cordis'']] (from Latin for ''bruising of the heart''). On isolated [[guinea pig]] hearts, as little as 5 [[millijoule|mJ]] was needed to induce release of [[creatine kinase]], a marker for [[muscle cell]] damage.<ref name="pmid16125216">{{cite journal |author=Cooper PJ, Epstein A, Macleod IA, ''et al'' |title=Soft tissue impact characterisation kit (STICK) for ex situ investigation of heart rhythm responses to acute mechanical stimulation |journal=Prog. Biophys. Mol. Biol. |volume=90 |issue=1-3 |pages=444–68 |year=2006 |pmid=16125216 |doi=10.1016/j.pbiomolbio.2005.07.004 |url=http://linkinghub.elsevier.com/retrieve/pii/S0079-6107(05)00060-X}}</ref> Obviously one should take into account that this figure does not include the dissipation of energy through the chest wall, and is not scaled up for humans, but it is indicative that relatively small amounts of energy are required to reach the heart before physical damage is done.
==Outcome and treatment==
[[Fulminant]] death is the most common outcome, because [[cardiopulmonary resuscitation]] requires quick action by a specialized medical team, using a [[defibrillator]] and cardioactive drugs, and these are rarely on hand in sports arenas. Due to the significant danger to children (death by ''commotio cordis'' is the first cause of fatalities in youth baseball in the US, with 2 to 3 deaths per year)<ref>Abrunzo TJ. Commotio cordis. The single, most common cause of traumatic death in youth baseball. ''Am J Dis Child.'' 1991 Nov;145(11):1279-82. Review. PMID 1951221</ref>, it has been recommended that "communities and [[school]] districts reexamine the need for accessible automatic defibrillators and cardiopulmonary resuscitation-trained [[coach (sports)|coach]]es at organized sporting events for children."<ref>Salib EA, Cyran SE, Cilley RE, Maron BJ, Thomas NJ. Efficacy of bystander cardiopulmonary resuscitation and out-of-hospital automated external defibrillation as life-saving therapy in commotio cordis. ''J Pediatr.'' 2005 Dec;147(6):863-6. Review. PMID 16356450</ref>
==Prevention==
[[Image:Sports-dress-codes.jpg|thumb|right|300px|Equipment and dress used in several sports. clearly demonstrating the lack of protection against chest concussion. From left to right, top to bottom: boxing, field hockey, baseball, karate, cricket, lacrosse and soccer.]]
The mandatory use of heavily padded special vests in front of the thorax is generally sufficient to prevent high energy impacts to the precordium. The problem with many sports such as soccer, baseball and karate is that, despite the danger posed by a multitude of punches, kicks, pads, mallets, bats, pucks and balls moving at high speeds, etc., their [[dress code]]s represent an obstacle to the use of mechanical protection to the precordium for all players, or at least for [[goalkeeper]]s, [[batting|batter]]s, ball [[catcher]]s, etc. For example, boxing traditionally requires a naked chest, cricket gear protects the legs but not the chest, and soccer has practically no protection gear at all; although the ball weights 450 grams, may reach speeds of 30 meters per second,<ref name="titleThe physics of football - physicsworld.com">{{cite web |url=http://physicsweb.org/articles/world/11/6/8 |title=The physics of football - physicsworld.com |accessdate=2008-02-23 |format= |work=}}</ref> and barrier defenses actually encourage the reception of the ball against the chest.
Parents of children active in these sports are advised to adopt simple protective measures, particularly in informal "backyard" games, which are often much more dangerous than formal ones, which require some protection.
==Legal issues==
Several people have been convicted of involuntary [[manslaughter]] in cases involving insufficient and slow medical help to athletes who underwent ''commotio cordis'' during sports events,<ref>Maron BJ, Mitten MJ, Greene Burnett C. Criminal consequences of commotio cordis. ''Am J Cardiol.'' 2002 Jan 15;89(2):210-3. Review. PMID 11792344</ref> as well as in cases of intentional delivery of contusive blows. In one such case, a man was sentenced to 18 years of prison for killing his own son with a blow to the chest.
==See also==
*[[Pulmonary contusion]]
==References==
{{reflist|2}}
==Further reading==
* {{cite journal |author=Kohl P, Nesbitt AD, Cooper PJ, Lei M |title=Sudden cardiac death by Commotio cordis: role of mechano-electric feedback |journal=Cardiovasc. Res. |volume=50 |issue=2 |pages=280–9 |year=2001 |pmid=11334832 |doi= |url=http://linkinghub.elsevier.com/retrieve/pii/S0008636301001948}}
* {{cite journal |author=Geddes LA, Roeder RA |title=Evolution of our knowledge of sudden death due to commotio cordis |journal=Am J Emerg Med |volume=23 |issue=1 |pages=67–75 |year=2005 |pmid=15672341 |doi= |url=http://linkinghub.elsevier.com/retrieve/pii/S0735675704002669}}
==External links==
* [http://www.jhu.edu/trayanova/research/lab/projects/each/weihui_CommotioCordis/2320.avi Induction of Ventricular Arrhythmias Following A Mechanical Impact: A Simulation Study in 3D].
* Yabek, S.M. [http://www.emedicine.com/ped/topic3019.htm Commotio cordis]. [[eMedicine]], September 2005.
* [http://theacc.collegesports.com/sports/m-lacros/spec-rel/030105aaa.html Sports Sciences Feature: Commotio Cordis: Sudden death following chest wall trauma]. ACC.
* [http://www.escardio.org/knowledge/OnlineLearning/slides/ESC_Congress_2005/Kohl-FP1296/ Mechanical effects on heart rhythm: from commotio cordis to pre-cordial thump]. PowerPoint slides, by P. Kohl. Sept. 2005 (n PDF).
* [http://www.erc.edu/index.php/ilcor/en/ International Liaison Committee on Resuscitation (ILCOR)]
* [http://circ.ahajournals.org/content/vol112/24_suppl/ American Heart Association guidelines on resuscitation]
* [http://www.resus.org.uk/pages/mediMain.htm Resuscitation Council (UK) guidelines on resuscitation]
{{Injuries, other than fractures, dislocations, sprains and strains}}
{{chest trauma}}
[[Category:Chest trauma]]
[[Category:Cardiology]]
[[Category:Sports medicine]]
[[de:Herzverletzung]]