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Heart AttackWhat causes a Heart Attack (Myocardial Infarction) Heart attacks are usually caused by plaques, or blockages in the blood vessels that supply blood to the heart itself; called the coronary arteries. The heart’s job, as you may know, is to pump blood into the lungs and out to the rest of the body where the blood can deliver oxygen to all the parts of your body that need it. Over time plaques can grow on the walls of your blood vessels and slowly begin to “close off the tube” that the blood travels in. What is interesting is that most heart attacks do not happen after a plaque completely closes off the blood vessel, but rather happen when a medium size plaque ruptures (opens up). The stuff inside the plaque then comes into contact with your blood and sets off what doctors call a clotting cascade. This is the same system that would eventually stop a cut on your body from bleeding. So inside the blood vessel with the plaque that ruptured, your body forms a clot (like a wall) and blocks any blood from getting though to the heart muscle. Really anything that stops the blood from getting to the heart’s muscle can cause a heart attack. So, anything that closes off the blood vessel (the tube delivering the blood) will cause a heart attack. Other things that can heart attacks, besides the plaques as we talked about, include: 1) Embolus- This is a clot from another part of the body that breaks off and travels in the blood until it gets stuck in a smaller blood vessel. An embolus can get stuck anywhere really and depending on where it gets stuck, different things can happen. For example, if an embolus gets stuck in the blood vessels in the heart it will cause a heart attack, if an embolus gets stuck in the blood vessels in the brain it can cause a stroke (death of brain tissue due to lack of blood and oxygen supply), etc. 2) Coronary artery vasospasm- Coronary arteries are just the names of the blood vessels that take blood to the heart muscle. Vasospasm means that the blood vessels close off. A good way to visualize vasospasm is by imagining a rubber tube is your blood vessel. If you were to squeeze the tube in your hand hard enough you would close off the tube and nothing could get through. In vasospasm, the tube is being squeezed just like this and is closing itself off. Vasospasm can occur on its own with no real cause, or it can happen after things like cocaine use. 3) Vasculitis- This means you have inflammation of a blood vessel. When things get inflamed, as you may know, they get swollen among other things. Swelling, if severe enough, can close off the tubes just like any of the other things we have talked about above. ***They key idea as to what causes a heart attack is that something is causing the blood to not be able to get through the tubes taking it to the heart muscle. Most often this is a plaque that opens up and causes a clot to form.*** What causes plaques to form If you were to look hard enough, you could find a plaque in anyone alive today. In fact, some research has shown that people start to form plaques in their blood vessels as early as 2-3 years old. As you get older, these plaques can increase in number and size. Below is a list of some of the things that can increase your risk of forming plaques in your blood vessels. 1) Diabetes 2) High Cholesterol- especially high LDL. 3) High Blood Pressure 4) Smoking 5) Advanced age- one of the few things you do not have control over. 6) Diet- high fat diets, especially those high in trans fat or saturated fats. A real basic explanation of how plaques form is that the bad type of cholesterol, known as LDL, starts to build up in the wall of your blood vessels. Your body does not like the LDL there, so it sends some cells into the wall called macrophages that have the job of trying to get the LDL out. This doesn’t always work very well, especially if you have high LDL cholesterol (and therefore a lot of LDL in the walls) and as a result rather then helping remove the LDL, the macrophages eventually add onto the problem and just make the plaques bigger. Things like high blood pressure, diabetes and smoking make this formation of plaques happen much faster. What are some things people with a Heart Attack (Myocardial Infarction) experience There are actually no specific findings that can be seen in all people who are having a heart attack. However, listed below are some of the things that may be seen in someone who is having a heart attack: 1) Chest pain- people usually describe this as a crushing pain right in the middle of their chest. Someone who has had a heart attack may describe it as if an elephant were sitting on their chest. Often pain can also be noticed in the left shoulder as well. However, any chest pain whatsoever should be a concern to you and you should mention it to your doctor. 2) Dsypnea- this is a word that means someone is short of breath or is having trouble breathing. 3) Feeling of something being very wrong 4) Diaphoresis- this means people can get very sweaty. 5) Stomach pain- this type of pain with heart attacks is much more commonly seen in women and people with diabetes. 6) Anxiousness 7) Nausea- feeling like you have to throw up. 8) Sudden death How is a Heart Attack (Myocardial Infarction) diagnosed? In order to diagnose a heart attack, a doctor has to do three things: 1) Talk with you and examine you- important things will include any of the above listed symptoms including chest pain, shortness of breath, sweating and a heart exam. 2) Order an EKG- this is a test that looks at how your heart is beating. Your doctor can look at these tests and see if any changes can be seen that signal a heart attack is happening. For example, a very common change seen on an EKG that signals to a doctor you hare having a heart attack is called ST segment elevation. This just means that a line on your EKG called the ST segment is higher then it should be. 3) Order Cardiac enzymes- Cardiac muscle (heart muscle) has things inside its cells called enzymes that help the muscle cells perform all the things it needs to do to work well. When these muscle cells die (because they are not getting enough blood and oxygen) they open up and release their enzymes into the blood. This causes these enzymes to be present in the blood and as a result your doctor can see if any heart muscle is dying with a blood test. Several of these enzymes commonly measured by doctors include: Troponin and CK-MB. In general, if two or more of these are abnormal, your doctor will diagnose you with a heart attack (Myocardial Infarction). How is a Heart Attack (Myocardial Infarction) treated? Because Heart attacks are most often caused by plaques opening up in your blood vessels and causing clots to form, one of the best first treatments is Aspirin. Aspirin blocks your body’s ability to form blood clots and by doing so it stops you from closing off the tube any more. Specifically, Aspirin blocks cells in your blood called platelets, which are big players in the formation of blood clots. Another drug that works like Aspirin that is often used is called Heparin. Some medicines are also used to slow the heart down and keep it from working too hard. This is very helpful as muscle that is not working as hard does not need as much blood and oxygen. Therefore, these medications decrease the amount of muscle that actually dies during a heart attack. A good example of such medications includes Beta-blockers. The basic idea behind treating people with heart attacks is to either 1) open the blood flow back up or 2) provide new routes for the blood to flow and get to the muscle. Unlike Aspirin and Heparin, which try and keep the tubes from closing off completely, several treatments can actually open the tubes back up if they are already closed completely. For example, there are medications, such as streptokinase, that can bust through the clot already formed and get blood flowing again. Along with this medication, some people may go to “the Cath lab.” The Cath lab is where Cardiologists (doctors who specialize in the heart) take people and can put things in your blood vessels called stents. These small metal devices actually hold your blood vessels open wider and allow blood to come through. Finally, surgery may be an option for some people especially if they have a lot of blood vessels that have plaques in them. This surgery is called coronary artery bypass grafting or CABG. CABG is when doctors take veins from other parts of your body (usually your arm and leg) and use them in your heart to make new connections blood can flow to the muscle. Just think of CABG as making more roads in a busy city. If you have a lot of traffic jams, adding more roads will make traffic flow much better. To read about your medication used in prevention of or treatment after a heart attack, see our medication link. | |
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