In an article published in The Conversation, experts detailed the phenomenon of commotio cordis following reports that Russian opposition leader and political prisoner Alexei Navalny died after receiving a blow to the chest. Commotio cordis is most often seen in athletes who receive blunt force trauma to the chest from hard objects such as sports equipment or collisions with other players. The experts explained that the precordium region of the chest rests just above the heart, which is further cushioned by a sac of membranes comprised of shock-absorbing fat and fluid known as the pericardium. Trauma delivered to this region in the form of a high-energy impact during the heart’s T wave upstroke—which accounts for only 1% of the heart’s cycle—can cause ventricular fibrillation and cardiac arrest. When this occurs, first responders must immediately initiate chest compressions, adrenaline, and automated external defibrillators to restore the heart’s rhythm. Although some experts have historically considered the possibility of a precordial thump to trigger tiny electrical currents and reset the heart’s rhythm, many others worry that the blow may exacerbate commotio cordis. Guidelines instructing first responders on the use of precordial thumps have been revised to omit the action after several studies have demonstrated that it may not benefit patients experiencing commotio cordis.