Heart attack - definition, causes, characteristics, diagnostics, course

Heart attack is one of the leading causes of death in Germany. The definition of a heart attack is: death of a different part of the heart muscle due to oxygen deficiency with sometimes life-threatening complications. Here you will learn how and why a heart attack develops, how to recognize it and what to do if you suspect a heart attack.

How does a heart attack develop?

As the motor of the circulation, the heart is the driving force of all circulation processes in the organism. Of course, the heart muscle also requires sufficient oxygen supply for its continuous, very energy-intensive pumping action. The perfusion of the heart muscle is ensured by the coronary vessels, which have their origin directly at the departure of the main artery and fan out like the branches of a treetop on the surface of the heart.

The heart muscle reacts very sensitively to circulatory disturbances lasting just a few seconds, while, for example, the arms or legs of the human suffer a circulatory failure, sometimes for several hours, without significant damage.

A heart attack occurs when the blood flow through the heart muscle is acutely restricted via the coronary vessels so that part of the heart muscle dies.

Causes of a heart attack

Such a myocardial infarction is based in the vast majority of cases on a chronic calcification of the coronary arteries, which is favored by high blood pressure, diabetes, lipid metabolism disorder, gout, obesity, smoking and genetic factors. Like limescale in the tubes of a washing machine, arteriosclerosis forms constrictions on the coronary arteries over the course of decades.

Complete occlusion of an important vessel - usually with an additional small blood clot - causes infarction.

However, heart attack mechanisms are also conceivable in which the coronary vessels are healthy. This would be the case, for example, when a blood clot from the heart itself is entrained in the bloodstream, enters the coronary vessels, clogs a healthy vessel there and triggers the heart attack.

In very rare cases, an acute thrombosis of a primarily healthy coronary vessel or even a vascular spasm as the cause of a heart attack comes into consideration.

The possible causes of a heart attack again at a glance:

  • Atherosclerosis (arteriosclerosis)
  • Embolism (carry-over of a blood clot)
  • Thrombosis (local formation of a blood clot)
  • Vascular spasm (vasospasm)

General information about heart attacks

Heart attack is the most serious complication of coronary heart disease. In Western industrial nations, it is in the lead in the cause of death statistics. On average, about 300 to 400 out of 100, 000 35- to 64-year-old men die as a result of a heart attack. Between the ages of 45 and 50, heart attacks are much more common in men than in women.

In older people, these differences are similar again. In addition, it has been observed that the incidence of coronary heart disease and heart attacks has increased significantly in women over the last few decades, most likely as a result of nicotine use and contraceptive pills.

The arteriosclerosis on the coronary arteries can individually assume very different forms and also lead to the most diverse symptoms. If there are only small constrictions of the coronary vessels - usually less than 70 percent of the vessel diameter - no symptoms at all must occur. The extreme form would be given by the complete closure of a coronary artery with myocardial infarction.

In between, there are fluid transitions between angina pectoris complaints with stronger physical stress (stress angina) up to angina pectoris at rest (Ruheangina), which may already be a harbinger of myocardial infarction. In addition, the severity of the discomfort of a patient in calcification of the coronary arteries also depends on his physical training state and possible comorbidities such as diabetes.

Characteristics and symptoms

Regular physical training improves the circulation of the heart muscle, which is therefore also better prepared for a heart attack. Myocardial infarction may, in some cases, be the first and most dramatic manifestation of vascular calcification on the coronary arteries. So it can come in the case of an apparently healthy people out of the blue out to the occurrence of a heart attack with fatal outcome.

The heart attack can also be at the end of a long-term increase in angina pectoris complaints.

The classic symptoms of heart attack include:

  • Strong, oppressive chest pain, sometimes radiating to the left arm ("as if an iron ring is contracting around the chest")
  • cold sweat
  • difficulty in breathing
  • paleness
  • Flat, fast pulse
  • anxiety

However, a heart attack can also hide behind much less typical symptoms such as jaw pain, abdominal pain, back pain, nausea, vomiting, shortness of breath, fainting or cardiac arrhythmias. In isolated cases one speaks also of mute heart attacks, which are usually diagnosed only randomly years later in the electrocardiogram (ECG).

Fast action required

If there is a suspicion of a heart attack, the highest alert level is required. Even of the patients who can still be brought to the hospital in this life-threatening emergency situation, 15 to 30 percent die in the following hours. If the heart attack survives, three percent of patients still die each year from complications such as malignant arrhythmias, recurrent heart attacks, or congestive heart failure.

About the concrete triggering causes of a heart attack in individual cases, it is often speculated by laymen. Contrary to popular belief, experience has shown that rest and relaxation situations are much more common than stress situations in which heart attacks occur.

Diagnosis by ECG and blood tests

The diagnosis can be made with appropriate symptoms only by an ECG and certain blood tests, since the transitions between circulatory disorders in angina and a proper heart attack run smoothly. On the ECG, the doctor sees typical changes that indicate a heart attack: in addition, the region of the heart - front wall, back wall or side wall - that is affected by the infarction can also be determined.

The blood tests in turn provide information about the extent and stage of myocardial infarction. It is crucial for the treatment to know the exact stage and ideally to initiate first measures at the earliest possible stage of myocardial infarction.

Course of myocardial infarction

If the onset of myocardial infarction is already more than four to six hours after diagnosis, major irreversible damage to the heart muscle must already be expected. The dead part of the heart muscle is usually replaced by the body within 10 to 14 days by a connective tissue scar, as after burning the skin.

Of course, this scar material does not have the capacity of the previously intact heart muscle, so that after a heart attack often a heart muscle weakness persists to heart failure.

If no clear diagnosis is possible

Sometimes the diagnosis - especially with small infarcts - can not be clearly stated. In case of doubt, however, a patient will be treated for safety reasons, just like with a proper infarction. In addition to the indirect methods such as blood tests and ECG, the changes in the coronary arteries can be viewed directly only through a cardiac catheterization.

In this procedure, the coronary arteries are retrieved via long plastic tubes, which are advanced over the inguinal vessels to the heart, and visualized with X-ray contrast medium. Classically, a closed infarct vessel is found in acute myocardial infarction. In addition, in the region of the heart muscle, which was formerly supplied with blood by the infarct vessel, a diminished contraction force can be detected.

Even years after a heart attack, the regionally reduced contraction force of the heart muscle persists and can be diagnosed by a cardiac catheterization or - far less costly - by an ultrasound examination of the heart. However, if the coronary arteries are inconspicuous in the cardiac catheterization in acute infarction, there is a suspicion of embolic infarction (with self-dissolution of the blood clot) or rarely on a vasospastic infarction.

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