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Updated: Thu, 07/18/2024 - 18:12

Gradual reopening continues on downtown campus. See Campus Public Safety website for details.

La réouverture graduelle du campus du centre-ville se poursuit. Complément d'information : Direction de la protection et de la prévention.

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Damar Hamlin and the Importance of Defibrillators

While we cannot yet know for sure what happened to Hamlin, most people who witnessed the event believe he suffered from commotio cordis.

This article was originally posted in the Montreal Gazette.

It is terrible to see a young, healthy man go into cardiac arrest on live TV. Damar Hamlin’s teammates and the opposing players were visibly shaken by his sudden collapse, and with good reason. While we cannot yet know for sure what happened to Hamlin, most people who witnessed the event believe he suffered from commotio cordis.

Commotio cordis is mercifully not common, with only a few hundred cases reported since a national registry was established in the United States. It seems strange that a seemingly benign blow could trigger a heart arrhythmia, and yet there have been enough documented cases and experimental evidence in animals to prove that triggering an arrhythmia in this way is possible.

It is, of course, a remarkably rare occurrence. A blow with enough speed and force has to strike the chest in just the wrong place at just the wrong time in a very narrow window in the cardiac cycle while the heart is depolarizing and vulnerable to an arrhythmia. It is commonly described in sports like hockey and baseball where balls and pucks are propelled at high velocities and can strike players in the chest.

It is uncertain whether commercially available sports equipment offers up any real protection. Whether this means that chest protectors are ineffective or whether we just need better designed chest protectors is unclear. Using softer baseballs does seem to reduce the risk, probably because it reduces the trauma to the chest wall and the amount of kinetic energy transferred to the heart with the contact. This probably is especially important in younger age groups, where the risk is higher. The average age for this type of cardiac arrest is actually 15 and occurs mainly in boys, though this might simply be because boys are more likely than girls to take up sports like football, baseball and hockey.

No doubt many parents will be worried for their children, so it is worth repeating how rare this event truly is.

The best prevention strategy is preventing the injury itself. Coaching and educating young athletes to avoid shots directly to the chest is key. And while this might seem like an obvious thing to say, it has to be ingrained in sports culture.

However, the most important take-away from the story of Damar Hamlin in particular and sudden cardiac death in general is the role of defibrillators. When you suffer a severe arrhythmia, as one does in commotio cordis, the heart stops pumping blood to the rest of the body. The only way to re-set it is with a shock to the heart from an automatic electronic defibrillator (AED); the device was used on Hamlin.

As I write this, Hamlin is in critical condition. Survival and a good prognosis are dependent on shocking the heart back into a normal rhythm as quickly as possible because every minute the heart is fibrillating is another minute the brain and other vital organs are being deprived of oxygen. Performing CPR will help a little bit by pushing some blood to the critical organs, but it is a defibrillator that will break the arrhythmia.

The reason the prognosis from commotio cordis and other causes of sudden cardiac death have improved over the past decades is the wider availability of defibrillators in public spaces. Training the public in CPR and in the use of defibrillators (which are actually very easy to use) is probably the most important thing we can do to save lives.

Whether a cardiac arrest occurs from a pre-exisiting genetic problem like hypertrophic cardiomyopathy or long QT syndrome, or commotio corids, or even a heart attack in an older person, the prompt use of a defibrillator will probably make the difference between life and death and between neurological recovery and persistent deficits.


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