Task Force 11: Commotio cordis

Commotio Cordis: A Comprehensive Review

Commotio cordis is a rare, however, potentially fatal, cardiovascular phenomenon arising from direct chest wall trauma, causing sudden cardiac arrest and potentially death. It is primarily seen in young athletes who participate in contact and organized sports. Though debated, the cause of commotio cordis is believed to involve specific timing of chest impact during ventricular electrical activity leading to severe arrhythmic events. Due to sudden onset, the first step in management is immediate and effective basic life support with automated external defibrillation, followed by advanced cardiac life support. Future considerations should include secondary prevention measures such as protective padding in contact sports. It is paramount that clinicians are vigilant in recognizing potential cases of commotio cordis in the field and provide immediate care. This review consolidates the current understanding of commotio cordis, emphasizing the importance of awareness and early intervention. Future research is warranted, including retrospective and observational studies to identify high-risk patterns or trends associated with the condition.

Commotio Cordis in 2023

Since the nationally televised cardiac arrest of American National Football League player Damar Hamlin in January 2023, commotio cordis has come to the forefront of public attention. Commotio cordis is defined as sudden cardiac arrest due to direct trauma to the precordium resulting in ventricular fibrillation or ventricular tachycardia. While the precise incidence of commotio cordis is not known due to a lack of standardized, mandated reporting, it is the third most common cause of sudden cardiac death in young athletes, with more than 75% of cases occurring during organized and recreational sporting events. Given that survival is closely tied to how quickly victims receive cardiopulmonary resuscitation and defibrillation, it is crucial to raise awareness of commotio cordis so that athletic trainers, coaches, team physicians, and emergency medical personnel can rapidly diagnose and treat this often-fatal condition. Broader distribution of automated external defibrillators in sporting facilities as well as increased presence of medical personnel during sporting events would also likely lead to higher survival rates.

Commotio Cordis in Non-Sport-Related Events: A Systematic Review

BACKGROUND

Commotio cordis is an increasingly recognized cause of sudden cardiac death. Although commonly linked with athletes, many events occur in non-sport-related settings.

OBJECTIVES

The goal of this study was to characterize and compare non-sport-related vs sport-related commotio cordis.

METHODS

PubMed and Embase were searched for all cases of commotio cordis from inception to January 5, 2022.

RESULTS

Of 334 commotio cordis cases identified, 121 (36%) occurred in non-sport-related contexts, which included assault (76%), motor vehicle accidents (7%), and daily activities (16%). Projectiles were implicated significantly less in non-sport-related events (5% vs 94%, respectively; P < 0.001). Nonprojectile etiologies in non-sport-related events mostly consisted of impacts with body parts (79%). Both categories affected similar younger aged demographic (P = 0.10). The proportion of female victims was significantly higher in non-sport-related events (13% vs 2%, respectively; P = 0.025). Mortality was significantly higher in non-sport-related events (88% vs 66%, respectively; P < 0.001). In non-sport-related events, rates of cardiopulmonary resuscitation (27% vs 97%, respectively; P < 0.001) and defibrillation (17% vs 81%, respectively; P < 0.001) were both lower and resuscitation was more commonly delayed beyond 3 min (80% vs 5%, respectively; P < 0.001).

CONCLUSIONS

Commotio cordis occurs across a spectrum of non-sport-related settings including assault, motor vehicle accidents, and daily activities. Both categories affected a younger and male-predominant demographic. Mortality is higher in non-sport-related commotio cordis, likely owing to lower rates of cardiopulmonary resuscitation, defibrillation, automated external defibrillator availability, and extended time to resuscitation. Increased awareness of non-sport-related commotio cordis is essential to develop a means of prevention and mortality reduction, with earlier recognition and prompt resuscitation measures.

Ventricular fibrillation arrest after blunt chest trauma in a 33-year-old man, commotio cordis?

Background

Commotio cordis is an event in which a blunt, non-penetrating blow to the chest occurs, triggering a life-threatening arrhythmia and often sudden death. This phenomenon is often seen in young, male athletes and has become increasingly well-known over the past few decades. We present a unique case in which ventricular fibrillation occurs in an older male athlete after blunt trauma.

Case presentation

Patient with no known medical history was brought to the ER after being found unconscious after a soccer ball kick to the chest. He was found to be in ventricular fibrillation and successfully resuscitated on the soccer field. Patient was admitted to the hospital and lab workup and initial imaging were unremarkable, except elevated troponin and lactate, which returned to normal levels. An echocardiogram showed global left ventricular systolic dysfunction with a visually estimated ejection fraction of 45–50%. Coronary showed angiographically nonobstructive coronary arteries. The patient was diagnosed with commotio cordis and discharged from the hospital in stable condition. Follow-up echocardiogram continued to show low ejection fraction and event monitor demonstrated frequent polymorphic ventricular tachycardia with periods of asystole.

Conclusion

This case is unique in that blunt trauma to the chest from a soccer ball immediately triggered ventricular fibrillation in a patient with a possible cardiomyopathy. It is possible that the blunt trauma caused primary commotio cordis that led to cardiomyopathy in a previous healthy man, or that an underlying cardiomyopathy made it more likely for this to occur. Overall, increased awareness and prevention efforts of blunt chest trauma are required to reduce the high mortality associated life-threatening arrhythmias. There is limited data regarding the interplay between these two entities.

A Lethal Blow to the Chest as an Underdiagnosed Cause of Sudden Death in United Kingdom Sports (Football, Cricket, Rugby)

Nonpenetrating blunt force trauma to the front of the chest can lead to commotio cordis, a cardiac rhythm disturbance, which can result in cardiac arrest and death. The condition is particularly noted during sport. No series of such cases has been published in the UK. This study is a retrospective analysis of a database of 6000 cases of sudden cardiac death examining commotio cordis in the setting of collapse and death shortly following a blow to the precordium where no structural heart disease was identified at autopsy. Of the 17 cases, 16 were male, and 11 were 18 years old or younger. Eleven occurred whilst playing sport while 6 involved physical interaction including assault. The most common circumstance of death involved a youth being struck in the chest by a ball during sporting activity. In conclusion, this study demonstrates that cases of commotio cordis in the UK follow a similar circumstantial and age profile to those reported in the United States, and indicates that ball sports such as football, cricket, and rugby expose young participants to a similar risk. There is currently no nation-wide registry of deaths occurring during sporting activity in the UK, and although the true incidence of this condition is not currently known, it is most probably under-recognised and underdiagnosed.

Catecholaminergic polymorphic ventricular tachycardia in children: analysis of therapeutic strategies and outcomes from an international multicenter registry

BACKGROUND

Catecholaminergic polymorphic ventricular tachycardia is an uncommon, potentially lethal, ion channelopathy. Standard therapies have high failure rates and little is known about treatment in children. Newer options such as flecainide and left cardiac sympathetic denervation are not well validated. We sought to define treatment outcomes in children with catecholaminergic polymorphic ventricular tachycardia.

METHODS AND RESULTS

This is a Pediatric and Congenital Electrophysiology Society multicenter, retrospective cohort study of catecholaminergic polymorphic ventricular tachycardia patients diagnosed before 19 years of age. The cohort included 226 patients, including 170 probands and 56 relatives. Symptomatic presentation was reported in 176 (78%). Symptom onset occurred at 10.8 (interquartile range, 6.8-13.2) years with a delay to diagnosis of 0.5 (0-2.6) years. Syncope (P<0.001), cardiac arrest (P<0.001), and treatment failure (P=0.008) occurred more often in probands. β-Blockers were prescribed in 205 of 211 patients (97%) on medication, and 25% experienced at least 1 treatment failure event. Implantable cardioverter defibrillators were placed in 121 (54%) and was associated with electrical storm in 22 (18%). Flecainide was used in 24% and left cardiac sympathetic denervation in 8%. Six deaths (3%) occurred during a cumulative follow-up of 788 patient-years.

CONCLUSIONS

This study demonstrates a malignant phenotype and lengthy delay to diagnosis in catecholaminergic polymorphic ventricular tachycardia. Probands were typically severely affected. β-Blockers were almost universally initiated; however, treatment failure, noncompliance and subtherapeutic dosing were often reported. Implantable cardioverter defibrillators were common despite numerous device-related complications. Treatment failure was rare in the quarter of patients on flecainide. Left cardiac sympathetic denervation was not uncommon although the indication was variable.

Outcomes of out-of-hospital cardiac arrest by public location in the public-access defibrillation era

BACKGROUND

The strategy to place public-access automated external defibrillators (AEDs) has not yet been established in real settings.

METHODS AND RESULTS

This, prospective, population-based observational study in Osaka, Japan, included consecutive out-of-hospital cardiac arrest (OHCA) patients with resuscitation attempts during 7 years, from January 2005 through December 2011. The trends in the proportion of public-access AED use and 1-month survival with neurologically favorable outcome were evaluated by location. Factors associated with neurologically favorable outcome (defined as cerebral performance category 1 or 2) after ventricular fibrillation were also assessed using multiple logistic regression analysis. A total of 9453 bystander-witnessed OHCAs of cardiac origin were documented and 894 (9.5%) of them occurred at public places. The proportion of public-access AED use significantly increased from 0.0% (0/20) in 2005 to 41.2% (7/17) in 2011 at railway stations and from 0.0% (0/7) to 56.5% (13/23) at sports facilities. Mean time from collapse to shock was 5.0 minutes among those who received shocks with public-access AEDs. The proportion of neurologically favorable outcome was 28.0% (33/118) at railway stations, 51.6% (48/93) at sports facilities, 23.3% (20/86) in public buildings, and 41.9% (13/31) in schools. In multivariate analysis, early defibrillation, irrespective of bystander or emergency medical service (EMS) personnel, was significantly associated with neurologically favorable outcome (adjusted odds ratio for 1-minute increment, 0.89; 95% confidence interval, 0.87 to 0.92).

CONCLUSIONS

This large, population-based OHCA registry demonstrated that earlier shock, irrespective the shock provider (bystander or EMS personnel), contributed to improving outcome, and a public-access defibrillation program was successfully implemented so that shocks with public-access AEDs were delivered to over 40% of bystander-witnessed OHCAs and time to shock was shortened in some kinds of public places.

Biomechanical considerations for assessing interactions of children and small occupants with inflatable seat belts

NHTSA estimates that more than half of the lives saved (168,524) in car crashes between 1960 and 2002 were due to the use of seat belts. Nevertheless, while seat belts are vital to occupant crash protection, safety researchers continue efforts to further enhance the capability of seat belts in reducing injury and fatality risk in automotive crashes. Examples of seat belt design concepts that have been investigated by researchers include inflatable, 4-point, and reverse geometry seat belts. In 2011, Ford Motor Company introduced the first rear seat inflatable seat belts into production vehicles. A series of tests with child and small female-sized Anthropomorphic Test Devices (ATD) and small, elderly female Post Mortem Human Subjects (PMHS) was performed to evaluate interactions of prototype inflatable seat belts with the chest, upper torso, head and neck of children and small occupants, from infants to young adolescents. Tests simulating a 6-year-old child asleep in a booster seat, with its head lying directly on its shoulder on top of the inflatable seat belt, were considered by engineering judgment, to represent a worst case scenario for interaction of an inflating seat belt with the head and neck of a child and/or small occupant. All evaluations resulted in ATD responses below Injury Assessment Reference Values reported by Mertz et al. (2003). In addition, the tests of the PMHS subjects resulted in no injuries from interaction of the inflating seat belt with the heads, necks, and chests of the subjects. Given the results from the ATD and PMHS tests, it was concluded that the injury risk to children and small occupants from deployment of inflatable seat belt systems is low.

Commotio cordis, therapeutic hypothermia, and evacuation from a United States military base in Iraq

BACKGROUND

Therapeutic hypothermia (TH) has been demonstrated to improve clinical outcomes after out-of-hospital ventricular fibrillation (VF) cardiac arrest. It remains unclear if TH can be safely and effectively used in the setting of traumatic arrest. Furthermore, the use of TH methods in the pre-hospital and transport environments remain poorly established and a domain of active investigation.

OBJECTIVES

To describe a case of successful TH utilization after blunt trauma with commotio cordis and pulmonary contusion, and to describe the continuation of TH during international fixed-wing aeromedical transport.

CASE REPORT

A 33-year-old active duty soldier suffered blunt chest trauma and immediate VF arrest. He was successfully resuscitated with cardiopulmonary resuscitation and defibrillation attempts. Given his ensuing comatose post-arrest state, he was therapeutically cooled and subsequently evacuated from Iraq to Germany, with cooling maintenance established in flight without the availability of training or commercial cooling equipment. The patient exhibited an eventual excellent neurologic recovery. To utilize TH for this patient, military physicians with limited local resources employed a telemedical approach to obtain a hypothermia protocol to develop a successful treatment plan.

CONCLUSIONS

The patient's successful resuscitation suggests that care should not be withheld for blunt trauma patients without vital signs in the field if VF is present, until the differential diagnosis of commotio cordis has been considered.

Commotio cordis

Content:

Commotio cordis is blunt, nonpenetrating trauma to the chest resulting in irregular heart rhythm and often leading to sudden death. This article presents the epidemiology, variables leading to commotio cordis, theories on predisposing factors, diagnosis, treatment, treatment outcomes, and return-to-play recommendations.

Evidence Acquisition:

A PubMed (MEDLINE) search for commotio cordis was conducted on July 1, 2008, and it yielded 106 results, of which 26 were used for this review, including experimental models, simulation studies, case analysis studies, case reports, general recommendation, review articles, and editorials.

Results:

There are more than 190 reported cases of commotio cordis in the United States. Forty-seven percent of reported cases occurred during athletic participation. Commotio cordis is the second-most common cause of sudden cardiac death in athletes. Occurrence of commotio cordis is related to time of impact during the cardiac cycle, direct impact over the heart, the hardness and speed of the projectile, and the ineffectiveness of chest barriers. As a result, the US Consumer Product Safety Commission recommends that softer “safety” baseballs be used for youth baseball. Resuscitation using defibrillation was effective in only 15% of cases. Resuscitation within 3 minutes resulted in a survival rate of 25% (17 of 68 cases). Survival drops to 3% when resuscitation is delayed beyond 3 minutes. Survival of commotio cordis has risen from 10% to 15% since 2001. Reduced ventricular ejection fraction has been identified in some commotio cordis survivors.

Conclusion:

Preventive measures, such as using soft “safety” balls and making automated external defibrillators available at sporting venues, can reduce commotio cordis morbidity and mortality. Chest protector designs can be improved to enhance protection. Return to play is best left to clinical judgment given that data are lacking with regard to susceptibility for reoccurrence.

Cardiac changes after simulated behind armor blunt trauma or impact of nonlethal kinetic projectile ammunition

BACKGROUND

Cardiac-related injuries caused by blunt chest trauma remain a severe problem. The aim of this study was to investigate pathophysiological changes in the heart that might arise after behind armor blunt trauma or impacts of nonlethal projectiles.

METHODS

Sixteen pigs were shot directly at the sternum with "Sponge Round eXact I Mpact" (nonlethal ammunition; diameter 40 mm and weight 28 g) or hard-plastic ammunition (diameter 65 mm and weight 58 g) to simulate behind armor blunt trauma. To evaluate the influence of the shot location, seven additional pigs where exposed to an oblique heart shot. Physiologic parameters, electrocardiography, echocardiogram, the biochemical marker troponin I (TnI), and myocardial injuries were analyzed.

RESULTS

Nonlethal kinetic projectiles (101-108 m/s; 143-163 J) did not cause significant pathophysiological changes. Five of 18 pigs shot with 65-mm plastic projectiles (99-133 m/s; 284-513 J) to the front or side of the thorax died directly after the shot. No major physiologic changes could be observed in surviving animals. Animals shot with an oblique heart shot (99-106 m/s; 284-326 J) demonstrated a small, but significant decrease in saturation. Energy levels over 300 J caused increased TnI and myocardial damages in most of the pigs.

CONCLUSION

This study indicates that nonlethal kinetic projectiles "eXact iMpact" does not cause heart-related damage under the examined conditions. On impact, sudden heart arrest may occur independently from the cardiac's electrical cycle. The cardiac enzyme, TnI, can be used as a reliable diagnostic marker to detect heart tissue damages after blunt chest trauma.

Sudden cardiac death following blunt chest trauma: commotio cordis

BACKGROUND

There have been numerous reports of sudden cardiac death attributable to the condition of commotio cordis. Primarily, these are reports from the USA. Although three Australian cases have been mentioned in the published literature, the present case appears to be the first described Australian case.

METHODS

A man was brought to the Emergency Department after sudden collapse while playing cricket. His medical history was suggestive of hitting by a cricket ball while batting.

RESULTS

The epidemiology and mechanism of arrhythmia induction in commotio cordis are discussed. The emergency management of commotio cordis is outlined.

CONCLUSIONS

Commotio cordis is rare in sports (and Emergency Medicine). However it has a high mortality rate, and rapid recognition of the condition allows early defibrillation, generally with a good outcome. The improvement of participant care is recommended at community and other sport events.

Causes of sudden cardiac arrest in young athletes

Knowledge of sudden cardiac death in young athletes is imperative for all physicians and allied health professionals. The complete differential diagnosis of a young patient with sudden cardiac arrest will result in proper work-up and treatment. In this article, we review several etiologies of sudden cardiac death, including hypertrophic cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, Wolff-Parkinson-White syndrome, long QT syndrome, Brugada syndrome, and commotio cordis. Clinical findings, work-up, treatment, long-term management, and athlete preparticipation screening guidelines are discussed.

Safety baseballs and chest protectors: a systematic review on the prevention of commotio cordis

OBJECTIVE

To determine whether chest protectors and/or safety baseballs reduce the incidence of commotio cordis during sport through a review of the best available evidence.

DATA SOURCES

PubMed, Ovid Medline, and Embase databases from 1950 to 2009. We selected articles according to "death, sudden, cardiac," "commotio cordis," "sports equipment," and "protective devices." We identified 17 articles in the systematic literature search. Of these, 7 articles met inclusion criteria. Three independent reviewers reviewed the articles. The study results and generated conclusions were extracted and agreed on.

RESULTS

The softest safety baseball shows statistically significant reductions in the incidence of ventricular fibrillation (VF) at all velocities compared with standard baseballs in the 3 studies that evaluated their use. Different degrees of softness did not show statistically significant reductions in VF. In the 3 studies that evaluated the use of chest protectors against controls, there was an increase in protection against fatal arrhythmias; however, this was only statistically significant for 1 chest protector.

CONCLUSIONS

This systematic review shows strong supportive evidence toward a decreased rate of commotio cordis with safety baseballs when compared with standard balls. Based on the results of our systematic review, the rate of induction of VF was at its lowest when chest protection was used.

Sudden cardiac death in athletes

Sudden cardiac death in athletes is an uncommon but extremely visible event because of the high profile of amateur and professional athletes and the expected excellent health of these athletes. However, paradoxically, athletic performance may immediately increase the risk of ventricular arrhythmias and sudden cardiac death while run reducing atherosclerosis, which thus improves cardiovascular health and longevity. In athletes younger than 30 years, the most common underlying causes are due to inherited heart disease. In the older athletes, sudden death is generally due to arrhythmias in the context of coronary artery disease. Many athletes with aborted sudden death, arrhythmia-related syncope, or high-risk genetic disorders benefit from therapy with implanted cardioverter/defibrillators (ICDs) . Although ICD therapy can effectively abort sudden death, implantation of an ICD generally prohibits an individual from all competitive athletics except low-intensity sports. The screening of athletes has been notoriously inadequate; however, the optimal screening strategies have yet to be determined. Recommendations for participation in competitive athletics generally follow the recently published 36th Bethesda Conference Eligibility Recommendations for Competitive Athletes with Cardiovascular Abnormalities.

Cell membrane stretch and chest blow-induced ventricular fibrillation: commotio cordis

INTRODUCTION

Commotio cordis, sudden cardiac death secondary to blunt nonpenetrating chest blows in sports, is reported with increasing frequency. In a swine model, ventricular fibrillation (VF) is induced by a baseball blow to the chest, and the initiation of VF is related to the peak left ventricular (LV) pressure produced by the blow. LV pressure changes likely result in cell membrane stretch and mechanical activation of ion channels. Disruption of cell cytoskeleton that anchors the cell membrane prior to precordial blows offers the opportunity to explore whether cell membrane deformation is critical to commotio cordis.

METHODS AND RESULTS

Twelve juvenile swine (mean 12.7 +/- 1.6 kg) were randomized to intravenous normal saline (control, n = 6) or 10 mg of intravenous colchicine (n = 6), which is known to depolymerize microtubules. Animals were given up to six blows timed to the vulnerable portion of the cardiac cycle with a 30 mph baseball on the chest directly over the cardiac silhouette. VF was initiated by 14 of the 29 (48%) impacts in the colchicine-treated animals compared with only 3 of 28 (11%) in the controls (P = 0.002). The peak generated LV pressure did not differ between colchicine animals (405 +/- 61 mmHg) and controls (387 +/- 115) (P = 0.47). However, animals administered colchicine were more likely to have VF generated by the chest blow at all pressures.

CONCLUSION

The initiation of VF by chest blows is significantly increased by selective disruption of the cytoskeleton, suggesting that mechanical deformation of the cell membrane is fundamental to the activation of ion channels and underlies the mechanism of VF in commotio cordis.

Sudden cardiac death in young athletes

Although regular aerobic physical activity increases exercise capacity and plays a role in both primary and secondary prevention of a variety of chronic disorders, competitive physical exercise is associated with a significant increase of risk of sudden death in athletes, especially adolescents and young adults. Several pathogenetic mechanisms have been speculated, including silent cardiovascular conditions, mostly cardiomyopathy, premature coronary artery disease and congenital coronary anomalies. Uneventful events, especially commotio cordis, and abuse of unfair and dangerous performance-enhancing drugs, are also claimed as potential causes. Although identification of athletes at major risk and prevention of adverse events seems the more pervasive strategy, guidelines for screening athletes differ widely on international basis and even among the different Sport federations. The aim of this review was to compile the current knowledge on the prevalence and the most common causes of sudden death in sportsmen, providing an overview of the guidelines for pre-participation screening.

Commotio cordis--sudden cardiac death with chest wall impact

Commotio cordis (CC), sudden death as a result of a blunt, often innocent-appearing chest wall blow, is being reported with increasing frequency. The clinical spectrum is diverse; however, a substantial number of cases occur in youth athletics. In events that occur during sport, victims are struck by projectiles regarded as standard implements of the game. Sudden death is instantaneous and victims are most often found in ventricular fibrillation (VF). Overall survival is poor; however, successful resuscitation can be achieved with early defibrillation. Autopsy is notable for the absence of any significant cardiac or thoracic injury. Development of an experimental model has allowed for substantial insights into the underlying mechanisms of sudden death. In anesthetized juvenile swine, induction of VF is instantaneous following chest wall blows occurring during a vulnerable window before the T wave peak. Crucial variables including the velocity of impact, impact location, and hardness of the impact object have been identified. Rapid left ventricular (LV) pressure rise following chest impact likely results in activation of ion channels via mechano-electric coupling. The generation of inward current via mechano-sensitive ion channels likely results in augmentation of repolarization and nonuniform myocardial activation, and is the cause of premature ventricular depolarizations that are triggers of VF in CC. While softer-than-standard safety baseballs reduce the risk of CC, commercially available chest protectors are ineffective in preventing CC. The development of more effective chest protectors and more widespread use of automated external defibrillators at youth sporting events are needed.

[The new 2005 resuscitation guidelines of the European Resuscitation Council: comments and supplements]

The new CPR guidelines are based on a scientific consensus which was reached by 281 international experts. Chest compressions (100/min, 4-5 cm deep) should be performed in a ratio of 30:2 with ventilation (tidal volume 500 ml, Ti 1 s, FIO2 if possible 1.0). After a single defibrillation attempt (initially biphasic 150-200 J, monophasic 360 J, subsequently with the respective highest energy), chest compressions are initiated again immediately for 2 min. Endotracheal intubation is the gold standard; other airway devices may be employed as well depending on individual skills. Drug administration routes for adults and children: first choice IV, second choice intraosseous, third choice endobronchial [epinephrine dose 2-3x (adults) or 10x (pediatric patients) higher than IV]. Vasopressors: 1 mg epinephrine every 3-5 min IV. After the third unsuccessful defibrillation attempt amiodarone IV (300 mg); repetition (150 mg) possible. Sodium bicarbonate (1 ml/kg 8.4%) only in excessive hyperkalemia, metabolic acidosis, or intoxication with tricyclic antidepressants. Consider atropine (3 mg) and aminophylline (5 mg/kg). Thrombolysis during spontaneous circulation only in myocardial infarction or massive pulmonary embolism; during CPR only during massive pulmonary embolism. Cardiopulmonary bypass only after cardiac surgery, hypothermia or intoxication. Pediatrics: best improvement in outcome by preventing cardiocirculatory collapse. Alternate chest thumps and chest compression (infants), or abdominal compressions (>1-year-old) in foreign body airway obstruction. Initially five breaths, followed by chest compressions (100/min; approximately 1/3 of chest diameter): ventilation ratio 15:2. Treatment of potentially reversible causes (4 "Hs", "HITS": hypoxia, hypovolemia, hypo- and hyperkaliemia, hypothermia, cardiac tamponade, intoxication, thrombo-embolism, tension pneumothorax). Epinephrine 10 microg/kg IV or intraosseously, or 100 microg (endobronchially) every 3-5 min. Defibrillation (4 J/kg; monophasic oder biphasic) followed by 2 min CPR, then ECG and pulse check. Newborns: inflate the lungs with bag-valve mask ventilation. If heart rate<60/min chest compressions:ventilation ratio 3:1 (120 chest compressions/min). Postresuscitation phase: initiate mild hypothermia [32-34 degrees C for 12-24 h; slow rewarming (<0.5 degrees C/h)]. Prediction of CPR outcome is not possible at the scene; determining neurological outcome within 72 h after cardiac arrest with evoked potentials, biochemical tests and physical examination. Even during low suspicion for an acute coronary syndrome, record a prehospital 12-lead ECG. In parallel to pain therapy, aspirin (160-325 mg PO or IV) and in addition clopidogrel (300 mg PO). As antithrombin, heparin (60 IU/kg, max. 4000 IU) or enoxaparine. In ST-segment elevation myocardial infarction, define reperfusion strategy depending on duration of symptoms until PCI (prevent delay>90 min until PCI). Stroke is an emergency and needs to be treated in a stroke unit. A CT scan is the most important evaluation, MRT may replace a CT scan. After hemorrhage exclusion, thrombolysis within 3 h of symptom onset (0.9 mg/kg rt-PA IV; max 90 mg within 60 min, 10% of the entire dosage as initial bolus, no aspirin, no heparin within the first 24 h). In severe hemorrhagic shock, definite control of bleeding is the most important goal. For successful CPR of trauma patients, a minimal intravascular volume status and management of hypoxia are essential. Aggressive fluid resuscitation, hyperventilation, and excessive ventilation pressure may impair outcome in severe hemorrhagic shock. Despite bad prognosis, CPR in trauma patients may be successful in select cases. Any CPR training is better than nothing; simplification of contents and processes remains important.

Sudden cardiac death in Athletes

The impact of sudden cardiac death (SCD) in athletes has been highlighted by increasing media coverage, as well as medical and lay awareness of the entities associated with SCD. Common etiologies include cardiac abnormalities such as hypertrophic cardiomyopathy (HCM), arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD), and coronary artery anomalies, each with varying geographic incidence. New recommendations regarding noninvasive preparticipation screening have emerged in Europe, where the Italian experience of mandatory annual screening of athletes has been the forerunner in efforts to identify individuals at risk. Ongoing clinical efforts are underway to help define the role of implantable cardioverter defibrillators as a preventive measure in appropriate candidates with HCM or ARVD, as well as methods to limit the potential for SCD as a result of chest blows sustained in sports and other recreational activities by means of chest protectors and special sporting equipment for young athletes.

GENE EXPRESSION OF STRETCH-ACTIVATED CHANNELS AND MECHANOELECTRIC FEEDBACK IN THE HEART

1. Mechanoelectric feedback (MEF) in the heart is the process by which mechanical forces on the myocardium can change its electrical properties. Mechanoelectric feedback has been demonstrated in many animal models, ranging from isolated cells, through isolated hearts to whole animals. In humans, MEF has been demonstrated directly in both the atria and the ventricles. It seems likely that MEF provides either the trigger or the substrate for some types of clinically important arrhythmias. 2. Mechanoelectric feedback may arise because of the presence of stretch-sensitive (or mechano-sensitive) ion channels in the cell membrane of the cardiac myocytes. Two types have been demonstrated: (i) a non-specific cation channel (stretch-activated channel (SAC); conductance of approximately 25 pS); and (ii) a potassium channel with a conductance of approximately 100 pS. The gene coding for the SAC has not yet been identified. The gene for the potassium channel is likely to be TREK, a member of the tandem pore potassium channel gene family. We have recorded stretch-sensitive potassium channels in rat isolated myocytes that have the properties of TREK channels expressed in heterologous systems. 3. It has been shown that TREK mRNA is expressed heterogeneously in the rat ventricular wall, with 17-fold more expression in endocardial compared with epicardial cells. This difference is reflected in the TREK currents recorded from endocardial and epicardial cells using whole-cell patch-clamp techniques, although the difference in current density was less pronounced (approximately threefold). Consistent with this, we show here that when the ventricle is stretched by inflation of an intraventricular balloon in a Langendorff perfused rat isolated heart, action potential shortening was more pronounced in the endocardium (30% shortening at 40 mmHg) compared with that in the epicardium (10% shortening at the same pressure). 4. Computer models of the mechanics of the (pig) heart show pronounced spatial variations in strain in the myocardium with large transmural differences (in the left ventricle in particular) and also large differences between the base and apex of the ventricle. 5. The importance of MEF and the non-homogeneous gene expression and strain distribution for arrhythmias is discussed.

Baseball and softball injuries

Baseball and softball injuries can be a result of both acute and overuse injuries. Soft tissue injuries include contusions, abrasions, and lacerations. Return to play is allowed when risk of further injury is minimized. Common shoulder injuries include those to the rotator cuff, biceps tendon, and glenoid labrum. Elbow injuries are common in baseball and softball and include medial epicondylitis, ulnar collateral ligament injury, and osteochondritis dissecans. Typically conservative treatment with relative rest, medication, and a rehabilitation program will allow return to play. Surgical intervention may be needed for certain injuries or conservative treatment failure.

The Science of Softball

Whilst the sport of softball has achieved worldwide popularity over the last 100 years, a consideration of the scientific principles underpinning softball is in its infancy. It is clear that the various motor skills associated with softball, such as pitching, batting and fielding, place considerable perceptual and physical demands upon players. Each of these skill categories are examined in more detail by reviewing the biomechanical principles associated with skilled performance. For pitching, a certain amount of information can be gleaned from baseball research; however, the underarm technique required by softball places the highest loads on the arm and shoulder during the accelerative, downward phase of the swing. Kinematic analyses of the bat swing suggest that elite batters have approximately 200 ms to decide whether to swing, and approximately the same duration to complete the swing (resulting in reported bat speeds of up to 40 m/sec). The research conducted on fielding has been limited to a consideration of throwing styles adopted in games. A variety of throwing techniques are adopted in the course of a typical game but elite players commonly adopt a sidearm technique when returning to base as quickly as possible. Data obtained from the National Athletic Training Association indicate a similar level of injury incidence in softball as in baseball. Approximately 17% of injuries are experienced by the pitcher and approximately 25% of all injuries are located in the forearm/wrist/hand joint segments. Sports science and sports medicine research have the potential to contribute significantly to performance enhancement and injury prevention in the future.