“Hearts cannot be broken, they're small squishy things
They don't break like glass but they bruise easily” – The Judybats
While hearts can’t be broken, their rhythmic beating can go awry – a condition we call arrhythmia. Many people don’t think of the heart as a muscle, but that’s what it is - a muscle that pumps blood around the body through a series of regular contractions. When the ventricles contract, oxygenated blood gets pumped out into circulation; when they relax, they fill back up with blood. Disruption of this routine delays delivery of blood to tissues and organs, including the brain.
Ventricular fibrillation is caused when a heart disorder leads to a problem with the electrical impulses running the cardiac muscles, which makes them quiver instead of contracting. A defibrillator basically sends an electric shock through the heart, stopping it in hopes that it starts back up with its normal rhythm restored. A remarkable feat that has saved tens of millions of lives, but how did we learn to do this?
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Ventricular fibrillation usually occurs as a consequence of previous cardiac damage, such as a heart attack. But what about the pain that we feel when someone “breaks” our heart? Believe it or not, stress-induced cardiomyopathy, also known as “broken heart syndrome” is a real thing! |
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Long ago, people used to believe muscles expanded and contracted because of air or fluid inside them. This was referred to as the “balloonist” theory. |
voltage shocks from electrodes placed on the head and one limb of a rat only resulted in a dead rat. But by 1933, he was able to restore normal heartbeats to dogs. However, this required direct contact with the dog’s heart muscle to work. This method of “open chest heart defibrillation” was practiced on patients until 1957, when Kouwenhoven built a device capable of delivering the electrical pulses from outside the body.
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Kouwenhoven’s defibrillation studies also led to the development of cardiopulmonary resuscitation (CPR) as a critical life-saving technique. One fine Saturday – because
all good scientists work through the weekends – a graduate student named Guy Knickerbocker noted a brief rise in blood pressure when he pressed those heavy copper defibrillator paddles onto the dog’s chest. This gave rise to the idea that by forcefully pressing on the chest, one could help circulate blood through the body until the heart started beating again.
*Kouwenhoven’s research stemmed from earlier findings, most notably those made by Jean-Louis Prevost and Frederic Batelli. In 1899, they observed that electrical shocks could induce ventricular fibrillation in dogs, but even larger shocks could restart their hearts.
Contributed by: Bill Sullivan
References:
Furman S (2002). Early history of cardiac pacing and defibrillation. Indian pacing and electrophysiology journal, 2 (1), 2-3 PMID: 17006571
Bresadola, M. (1998). Medicine and science in the life of Luigi Galvani (1737–1798) Brain Research Bulletin, 46 (5), 367-380 DOI: 10.1016/S0361-9230(98)00023-9
http://www.emsmuseum.org/virtual-museum/by_era/articles/399789-CPR-and-the-First-Defibrillator-Drs-Kouwenhoven-Jude-and-Knickerbocker
http://www.aed.com/blog/a-little-defibrillator-history-and-its-potential-future/#sthash.UjFv3BXE.dpuf
http://www.aed.com/blog/a-little-defibrillator-history-and-its-potential-future/#sthash.UjFv3BXE.dpuf
Furman S (2002). Early history of cardiac pacing and defibrillation. Indian pacing and electrophysiology journal, 2 (1), 2-3 PMID: 17006571