Cardiac Arrest in Athletes
Cardiac arrest in young athletes during sport activities has once again been brought to the spotlight. American football player, Damar Hamlin, suffered cardiac arrest during a game on January 2nd of this year, after he was tackled and sustained an impact to his chest. After the tackle took him to the ground, he stood up, and a few seconds later he collapsed and lost consciousness due to cardiac arrest. Fortunately, he was quickly resuscitated, and his heartbeat and circulation quickly restored. He was intubated, taken to the hospital where he underwent multiple tests, and a few days later was released in good health.
So why do very healthy athletes develop cardiac arrest while playing their sport? This can be due to one of the following causes:
1- A blow to the chest wall, leading to conversion from the normal heart beating to “ventricular fibrillation”, which is a form of cardiac arrest.
2- Structural heart disease, previously undetected, until the presenting cardiac arrest. This most commonly also leads to ventricular fibrillation as the cause of cardiac arrest. Most common structural heart disease include Hypertrophic Cardiomyopathy and Anomalous Origin of the Coronary Arteries.
3- Primary electrical diseases of the heart, in the absence of structural heart disease. Such diseases include Long QT Syndromes, Brugada Syndrome and catecholaminergic polymorphic ventricular tachycardia.
Damar Hamlin suffered a forceful chest impact during the football tackle, and this led to cardiac arrest. This is also known as Commotio Cordis, which is Latin and translates to “agitation of the heart”. In the United States, other sports in which cardiac arrest occurs due to forceful chest impact include baseball, lacrosse and hockey. Outside the United States, soccer, cricket and rugby are the main causes.
The mechanism leading to sudden cardiac arrest from Commotio Cordis is related to the location and velocity of the impact to the chest wall, in addition to the timing of the cardiac cycle. The impact has to be directly over the heart area, at velocities above 40 miles per hour. The impact has to occur within 20 to 40 milliseconds of the upsloping portion of the T wave on the ECG.
Registry data has shown that the mean age of occurrence of cardiac arrest from Commotio Cordis is 15 years, with less than 10% occurring in those older than 25 years of age, with 95% of cases occurring in males. The diagnosis is based upon a witnessed chest impact followed by collapse within about 5 seconds. The portable defibrillator when attached during resuscitation would show an irregular fibrillatory pattern of ventricular fibrillation; this is most commonly reverted to the normal sinus beating if a cardiac shock was delivered quickly. Every one-minute delay in resuscitation will reduce the chance of successful resuscitation by 10%.
There is no universal way to prevent cardiac arrest from Commotio Cordis during sport activities, and many different types of blows can cause it. Standard protective gear does not prevent its occurrence and many of the Commotio Cordis victims were wearing a proactive gear during the incident. Only specialized gear is protective, ones that follow the standards set by the National Operating Committee on Standards of Athletic Equipment. Players should be encouraged to turn away from incoming projectiles such as baseballs and lacrosse balls.