Damar Hamlin Collapse
Football watchers were shocked yesterday to witness the collapse and critical hospitalization of young healthy Damar Hamlin during the Bills-Bengal game. Physicians watching the game shared that shock but our minds quickly went into doctor-mode and tried to figure out what could have caused it. Doctors are trained to think in terms of a "differential". We looks at an event (collapse) and quickly gather environmental information to help us with a diagnosis. In this case the information we quickly gathered was:
He collapsed after a tackle and a helmet blow to the chest
He went into cardiac arrest
He was defibrillated with an AED and ? may have restored a heartbeat (this is not confirmed)
He remains in critical condition
He was young (age 23) and had no known illnesses
The "differential" are the many causes to explain the event or the condition. First possibility is a rare event called commotio cordis. This occurs after a blunt force to the chest wall that puts the heart into ventricular fibrillation. In a matter of seconds the blood supply to the brain causes collapse because the heart is no longer beating regularly. The heart has its own sophisticated electrical signaling system that coordinates systole and diastole contractions. If normal contractions aren't immediately restored, death results.
Other causes of sudden cardiac arrest in an athlete are structural within the heart itself. One is hypertrophic obstructive cardiomyopathy (aka:HOCM) This is an inherited genetic condition where the heart muscle becomes thickened and causes blood flow out of the heart to be restricted and can cause a sudden arrhythmia. It can be undiagnosed for years and is usually detected with an EKG and echocardiogram.
A healthy young person may have undetected changes in the coronary arteries or valves. This would be highly unlikely in an elite athlete without symptoms. An athlete could also have an undetected electrical disorder like "long QT syndrome" or "catecholaminergic polymorphic ventricular tachycardia" that predisposes to arrhythmia.
The most likely cause of his collapse is commotio cordis, given the blow to the chest. At this point it is speculation, but as physicians we are often speculating based on the information we have, until a diagnosis can be proven.
He is in the hearts and prayers of everyone who watches football.