Science Fact - Heart Attack Man

Everyone knows what a heart attack is, right? Or do they? When I was growing up I understood it as something that happened to your heart that messes it up for some reason, possibly leading to death but maybe not. My old definition wasn't very enlightened or scientific, but I knew enough to understand the seriousness of heart attacks and the lifestyle behaviours that could increase your risk. Now I know a lot more about heart attacks such as the causes, the various effects on the cardiovascular system, and how to treat someone who may be having a heart attack.

Before we dive headfirst into the cardiac world, I want to point out how many of us replace vague notions with more solid science as we get older. Good examples of this replacement are:

• 1. Realizing that meat is not a separate part of an animal, but is in fact muscle (thanks Morgan).


• 2. Understanding that bugs have organs similar to ours and are not just filled with yellow goo.


• 3. Watching a movie and realizing that the two people lying naked on a bed are doing more than just kissing.

So now what is a heart attack? The medical term is myocardial infarction (MI). Let's dissect this term: myo = muscle, cardiac = heart, and infarction = death or injury due to a lack of oxygen. Put together, we see that an MI is when heart muscle dies because there isn't enough oxygen getting to it. If you kill part of your heart, it won't work as well. Furthermore, the rest of the heart will have to work even harder to keep up with the body's demand. This added stress will make it more likely that your heart will poop out. Bad stuff all around.

What causes an MI in the first place? Wel, anything that would reduce or stop blood flow to the heart. And not the inner chambers of the heart (the atria and ventricles), but the outer blood supply that feeds the actual muscle. These vessels are known as coronary arteries. To illustrate this idea, think about a water pump. If you reduce the water flow inside the pump, it can still work. But if you cut the electricity that's actually 'feeding' the pump, then it stops working.

Things that can trigger myocardial infarctions are:

• Overexertion - Too much stress (physically or psychologically) for your heart to take, leading to a constriction of blood vessels and an increase in blood pressure. These two things can trigger an MI. If you're normally a couch potato, don't decide to get up and immediately run a marathon. Build up to your desired level of exercise.


• Blood Clots - A blood clot can form in your coronary arteries, or it can form somewhere in your body and then travel into one of your coronary arteries. The result would be the blockage of blood flow and ultimately MI. If instead it travelled to your brain, that would be called a stroke.


• Atherosclerosis - An atheroma is a build-up of junk (cell debris and cholesterol) inside the walls of your arteries. This is referred to as the 'hardening' of your arteries. The diameter of the arteries will shrink, making it harder for the heart muscle to get a proper blood supply. Furthermore, if the inner wall of the artery breaks open (possibly due to an increase in blood pressure) then this junk can block the blood vessels.

Before I wrap this up, I'd like to point out that myocardial infarctions are not the only things that can go wrong with your heart. Most people call everything a heart attack, but there are three main conditions that make up our classic idea of a heart attack. They are (1) myocardial infarctions, (2) cardiac arrest, and (3) ventricular fibrillation. Cardiac arrest is when your heart stops beating, and I shouldn't have to mention that it's pretty serious. Ventricular fibrillation, or V-fib, is when your heart is not contracting normally so it doesn't pump blood well. This can also lead to cardiac arrest. For people in V-fib, it is crucial that you do something to get their heart back on track, something to stop the fibrillation. That's why we use the shocking machine, otherwise known as a 'defibrillator'.