What is the cause of myocardial infarction?

September 29, World Heart Day. I just have a question about “myocardial infarction”, so let’s talk about it.

Cardiovascular disease is the number one killer of various diseases in our country. From the statistical data, since the 1990s, cardiovascular disease has always been the first cause of death for urban and rural residents in my country, and there are 2 cases of cardiovascular disease in every 5 deaths.

According to the “China Cardiovascular Health and Disease Report 2021”, there are about 330 million cardiovascular disease patients in my country, including 245 million hypertension, 11.3 million coronary heart disease, 13 million stroke, and other There are also 8.9 million heart failure, 4.87 million atrial fibrillation, pulmonary heart disease, rheumatic heart disease, congenital heart disease, etc. There are also many lower extremity arterial diseases, 45.3 million. In this way, one out of every three or five people has a cardiovascular disease.

In cardiovascular disease, myocardial infarction is an emergency that can lead to sudden death. So, here comes the problem.

What causes a heart attack?

Myocardial infarction, myocardial infarction, is caused by sudden and complete occlusion of the coronary arteries supplying blood to the heart muscle, resulting in myocardial ischemia and necrosis.

A sudden, complete occlusion of a coronary artery.

Because if it is a chronic occlusion, during the slow occlusion process, the blood vessels of the heart will open up collateral circulation. Therefore, some people do coronary angiography and see that the blood vessel is completely blocked, but there is no myocardial infarction. This is the reason. Also, if the blood vessel is not completely occluded, it usually causes angina pectoris, myocardial ischemia attack, but not myocardial infarction.

In medicine, all ischemic necrosis caused by arterial occlusion is called “infarction”, such as cerebral infarction, pulmonary infarction, renal infarction, etc. The coronary artery supplying the heart muscle is blocked and the heart muscle is ischemic and necrotic, which is called “myocardial infarction”.

According to this principle, anything that can cause a sudden occlusion of a coronary artery can lead to a myocardial infarction. Such as coronary atherosclerotic occlusion, coronary thrombosis, vasculitis coronary stenosis and occlusion, foreign emboli blocking coronary arteries, and coronary artery spasm. But the most common and most common is coronary atherosclerosis, coronary heart disease, 95% to 99% of them are.

To say that coronary atherosclerotic stenosis is not formed in a day, why is it suddenly blocked?

The most common cause is the sudden rupture of unstable plaques in the coronary arteries and the formation of blood clots. The blood clot blocked the narrowed blood vessel.

Coronary atherosclerosis involves the formation of plaque, but plaque is not the same as plaque. Plaques that are weak and unstable, medically known as “vulnerable plaques”, are prone to rupture. There are a number of factors that can make plaque unstable and easy to break.

* The plaque is inflamed. Plaques with inflammation are not strong, just like the skin with inflammation is easy to fester, and plaques with inflammation are easy to break.

*Too much lipid in the plaque. When cholesterol is high, a lot of cholesterol enters the plaque, and there are more lipids and necrotic cells that eat lipids in the plaque. Just like making dumplings, if there is too much stuffing in the dumplings, the dumpling skin will be easily broken.

*The “cap” that covers the plaque surface is weak. There is a fibrous cap on the surface of the plaque, and if it is firm, it is not easy to break. When new, fast-growing plaques and inflammation are present, the fibrous cap is not strong and is easily broken.

* Then there is the strong constriction of the blood vessel, tearing apart the plaque. For example, nervousness, emotional agitation, elevated blood pressure, smoking, cold, etc., can stimulate blood vessels and cause coronary spasm, tearing plaque.

When blood vessels are damaged and inflamed, platelets are also particularly active, and they tend to stick together to form blood clots.

The formation of myocardial infarction has such a time course, so it is said that “time is the heart muscle”.

Under normal circumstances, myocardial necrosis begins to occur 20 minutes after complete ischemia. In about 1 to 2 hours, most of the myocardium in the infarcted area is necrotic. After 6 hours, the myocardial The whole layer is necrotic from the inside to the outside, which is called “transmural myocardial infarction” in medicine.

So, if the attack of angina pectoris is usually 10 minutes, not more than 20 minutes. If the chest pain persists for more than half an hour, it is either angina or myocardial infarction.

Myocardial infarction progresses rapidly, and the rescue should be timely and early, strive to open blood vessels within 2 hours (120 minutes). If it is too late, the myocardium is necrotic. Even if the blood vessels are opened, the necrotic myocardium cannot be resurrected. Therefore, cardiologists often say “Time is the heart muscle“, which is not a slogan.

How can we prevent myocardial infarction?

*From a big perspective, of course, it is necessary to prevent and control the “three highs” and prevent coronary heart disease!

* For patients with coronary heart disease, it is precisely because of these mechanisms of myocardial infarction that antiplatelet drugs such as aspirin or clopidogrel are used to Prevent thrombosis; Take “statin” drugs to lower blood lipids, lower cholesterol, and stabilize plaques, so that plaques are not easily broken, and can even be reduced.

Be aware that plaque stability and instability are interchangeable, and adherence to treatment is important.

* Avoid triggers. Keep a calm mind and avoid emotional agitation; stabilize blood pressure and avoid sudden rise; quit smoking, keep warm, and avoid factors that induce coronary spasm; avoid sudden exertion and increase the heart load.

* Once angina pectoris occurs, whether it is new or aggravated by existing angina pectoris, seek medical attention in time, and treat it before myocardial infarction.

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