I just read this report about a local cricketer who was hit by a ball in the front of the chest last night, and suffered a cardiac arrest as a result. The good news is that bystanders performed CPR on him until paramedics got there, who were able to shock him back into a normal rhythm :
The 25-year-old Greensborough man was batting against a fast bowler at cricket training when he was struck just over the heart.
Paramedic Phil Morey said the man went into cardiac arrest after being struck by the delivery.
“It is a very unusual circumstance – it’s not something that I have seen before,” he said.
Two senior coaches performed CPR on the man until paramedics arrived.
Mr Morey said that paramedics were able to revive the man with defibrillation, or electricity to the heart
How did this happen, you may wonder. Well, we need to know a bit of physiology to understand what went on here. The heart has an inbuild pacemaker, and a conduction system that distributes electrical impulses from that pacemaker across the heart muscle, which causes muscle fibers to contract, which causes blood to be pumped out into the circulation, so that tissues are supplied with oxygen. Without going into details, the graph of that electrical activity looks like this, when recorded on an ECG :
Now, a thump to the chest (with a fist, or a cricket ball for that matter) delivers about 5-10 Joule of energy, and if that energy is delivered at the wrong time in the electrical cycle of the heart, it may cause the heart to go into a condition known as ventricular fibrillation, chaotic and unordered electrical activity where no blood is being pumped into the circulation, including the brain, and subsequently the person will become unconscious, and, if this goes on unreversed, die. VF looks like this on the ECG trace :
So what happened here is that the impact of the cricket ball caused the heart to go into VF, and bystanders kept the circulation going with chest compressions until the ambulance paramedics got there to defibrillate the heart out of VF and into a normal rhythm, one where blood can be pumped into the circulation to deliver oxygen to the brain and other organs. Well done, everyone !