Heart attack (also called myocardial infarction) is a heart disease caused by the interruption of blood flow in one part of the heart.
It can lead to irreversible damage and death of the cells in this area of the heart.
Heart attacks are one of the leading causes of death for men and women around the world.
Although there are many different reasons for myocardial infarction, one of the main causes is partial or total occlusion of coronary arteries.
This occurs mainly due to the tearing of an arteriosclerotic plaque formation.
An atherosclerotic plaque can erode due to the action of enzymes called metalloproteinases.
These enzymes cause the plaques to flatten, but their strength may still be large enough to narrow the vessel. This leads to a change in blood flow from the coronary arteries to the heart muscle cells.
When the amount of blood reaching the heart is reduced over a long period of time, it triggers a process called the ischemia cascade. This leads to the death of the heart muscle cells due to hypoxia (lack of oxygen).
The damaged heart tissue transmits the electrical impulses more slowly than normal. This difference in the conduction velocity of the pulses can trigger an arrhythmia, which may be the cause of death in some people.
The most dangerous arrhythmia is ventricular fibrillation: a much too fast and irregular heartbeat, which is the main cause of sudden cardiac arrest.
Another dangerous arrhythmia is ventricular tachycardia: it causes too fast a heart rate, which no longer allows the heart to pump blood sufficiently to the different areas of the body.
This can lead to a reduction in cardiac output and a dangerous reduction in blood pressure, which can increase coronary ischemia and the extent of the infarction. The fulminant infarction or sudden death is more common in women, while men feel the harbingers of symptoms up to a week before.
Myocardial infarction usually affects people older than 40 years. However, it can also be a juvenile disorder if the person concerned has various risk factors.
Mortality is increased, it is estimated that about 8% of all deaths are caused by acute myocardial infarction.
The events preceding myocardial infarction lead to heart muscle damage and/or cardiac muscle death.
Types of myocardial infarction
According to the location of the plaques
- Anterior wall infarction: The occlusion is located in the left coronary artery and has a negative effect on the blood flow to the left ventricle. It is considered the most severe type of heart attack and the affected area is located on the front side of the heart muscle.
- Infarction of the posterior wall or inferior infarction: is less severe than on the anterior wall. The occlusion is located in a branch of the right coronary artery. The posterior heart muscle tissue is affected. The infarction of the right ventricle occurs in about 40% of cases of inferior infarction.
- Lateral wall infarction: is caused by occlusion of the circumflex artery and causes a laterally circumscribed infarction.
After the spread of plaques
- Patients with non-ST elevation infarction. It is abbreviated as NSTEMI, the interruption of blood flow in the heart occurs temporarily due to a partial occlusion of the arteries. The cell damage is minor. The heart enzymes in the blood are used for diagnosis, but no electrocardiogram (ECG) is performed.
- Patients with ST elevation infarction. It is abbreviated as STEMI, it is a permanent occlusion of the coronary artery. A significant part of the heart muscle dies due to lack of nutrients and oxygen from the blood. This is a serious heart attack that can be diagnosed on the basis of an ECG and the enzymes in the blood.
According to the severity of cell damage
- Massive transmural myocardial infarction, is a severe form of infarction. Cell necrosis is evident in all three wall layers of the heart muscle: endocardium (inside), myocardium (middle layer) and epicardium (outside).
- Massive non-transmural myocardial infarction: this type of myocardial infarction is characterized by cell death, which occurs on the inner wall surface of the heart muscle. It is less severe than transmural infarction.
- Miliary infarction, is localized in small, independent zones.
In addition, two other types of infarction can arise: with and without Q-spike.
These are classifications based on ECG results. The type of Q spike shows the prolonged occlusion of a coronary artery, one notices deep Q spikes on the ECG.
On the other hand, the non-Q-jagged infarction indicates a prolonged partial or a short-term complete occlusion of the coronary artery.
There is no marked difference in the ECG result.
Causes of myocardial infarction
- Nutrient-poor diet
- Low oxygen levels in the blood
- Fast heartbeat
- Overactive thyroid gland (hyperthyroidism)
Risk factors of myocardial infarction
- Familial heart attack
- Chronic alcohol consumption
- High blood pressure (or hypertension)
- Night work (people who work shifts are more likely to develop myocardial infarction)
- High-cholesterol diet
If the patient is not aware of the initial symptoms, the risk of partial or complete heart muscle damage increases.
Symptoms of myocardial infarction
The symptoms vary from person to person.
Furthermore, it is observed that the symptoms in women are very different from those in men. The patient’s clinical picture may include the following common symptoms:
- Chest pain: You may feel discomfort, such as tightness, pressure, or a stinging sensation in the middle of the chest that lasts for a few minutes.
The complaints can come and go at intervals.
- Pain in the upper part of the body: One may feel a pain or diffuse discomfort on the shoulder, arm, back, neck, teeth or jaw.
The pain can also occur in the upper part of the body without discomfort in the chest.
- Stomach pain: The pain may extend down to the abdomen and you may also feel heartburn.
- Anxiety: there may be a feeling of anxiety or depression, similar to a panic attack for no apparent reason.
- Sweating: sudden cold welding.
- Nausea and vomiting: one suffers from stomach pain or nausea.
- Increase in the enzyme GOT in the liver, which occurs within 8 hours and persists for a few days.
However, women show different symptoms compared to men. In addition to pain and discomfort, they may also experience the following symptoms:
- Back pain, pain in the neck, jaw, shoulder or abdomen
- Shortness of breath
- Nausea or vomiting
- Stomach ache
- Dizziness or vertigo
- Unusual or unexplained fatigue
Silent heart attack differs from the classic heart attack because it does not cause pain or tightness in the chest. However, other symptoms occur (for example, sweating, nausea, jaw pain, etc.).
Consequences and risks of myocardial infarction
Complications of myocardial infarction include:
- Ventricular fibrillation
- Swollen legs and ankles
- Ventricular aneurysm
- Ventricular arrhythmia
In the first 6 months after the infarction, it is not allowed to have dental treatments performed.
a heart attack
A mild myocardial infarction can be distinguished from stable angina pectoris only by analyzing the electrocardiogram (ECG).
If the ECG curve over a region shows an ST-segment elevation, the patient should be diagnosed with a typical myocardial infarction.
If the curve does not show an ST segment elevation, the patient is diagnosed with a mild heart attack.
Alternatively, a mild heart attack may be detected by blood tests. If two markers (proteins) called troponin and creatine kinase MB (CK-MB) can be detected in laboratory tests of the blood, it means that the patient has suffered a mild heart attack.
Some other non-invasive examinations consist of echocardiogram, echography of the heart, nuclear medicine, angiogram or radiography of the coronary arteries.
What to do? Therapy for a heart attack
In the acute phase, the therapy serves to restore blood circulation as early as possible. The choice of therapy varies depending on the extent of damage to the heart muscle tissue.
Patients who have suffered only a mild heart attack usually do not need surgical intervention to restore normal circulation.
In the case of an infarction suffered, the focus is primarily on treatment, which is able to restore normal blood flow to the heart. This includes the following medications:
drugs Aspirin is an antiplatelet drug.
It reacts with the platelets, the blood cells that form blood clots.
Antiplatelet drugs such as aspirin significantly reduce the size of blood clots, thus promoting normal blood flow to the heart.
Therapy based on aspirin over a certain period of time reduces the likelihood of a future heart attack to a minimum
Thrombolytics or fibrinolytics
When it comes to interfering with the formation of blood coagles or dissolving them, fibrinolytics such as anistreplase can be administered. These drugs destroy blood clots and effectively eliminate arterial occlusions.
Thrombolytics have the goal of reopening arteries or preventing the formation of new blood clots.
Beta-blockers such as acebutolol (Prent) are commonly used in the treatment of arterial hypertension. With the lowering of blood pressure, the heart needs less blood and oxygen to function effectively. It also increases the heart’s ability to relax, which serves overall well-being.
As the name suggests, vasodilators are formulated to dilate blood vessels and improve blood flow to the heart.
As blood flow increases, so does the influx of oxygen to the heart.
These positive changes in blood flow serve to improve the condition of the heart and reduce possible damage.
To lower cholesterol, doctors can prescribe statins.
These drugs reduce bad cholesterol.
Surgery for heart attack and first aid
A severe heart attack must be treated surgically because medication cannot open the blocked arteries. Some surgical procedures are described below:
This procedure consists of using a long and thin tube (catheter) to open the artery. Before starting the procedure, doctors need to locate the occlusion. This is done using the angiogram (X-ray, which provides images of what is happening in the arteries).
Once the position of the occlusion has been determined, the catheter is inserted via a leg artery. Then the catheter is advanced to the point where the blood clot is located.
Then the balloon attached to the catheter is stretched to remove the occlusion. In this method, a stent made of a metallic grid can also be attached to the closed site. The grid prevents the artery from narrowing at this point, thus reducing the likelihood of future cardiac problems.
In this surgical procedure, the blood circulation is routed around the occlusion site (bypass). For this purpose, a chest wall artery is connected to a coronary vessel running above and below the constriction. This ensures that the occlusion does not affect the blood flow and allows proper blood flow to and from the heart.
Cardiac rehabilitation and prevention of a heart attack
After an infarction, cardiac rehabilitation is important in order to promote a resumption of everyday activities.
You are not allowed to exercise during the initial period after the heart attack, but light physical activity is recommended as soon as the doctor allows it. For example, you can walk, swim or cycle.