OccurrenceFrequency
Heart attacks are the leading cause of death for the population in industrialized countries. In Germany, about 200,000 people die from a heart attack every year. Men have a risk of about 30% of their lives to suffer a heart attack, for women in Germany this risk is about 15%.
Cause of the heart attack
In more than 95% of cases, heart attacks occur at the base of coronary artery disease: the walls of the coronary arteries are damaged by atherosclerosis by so-called plaques attaching themselves to the walls of the vessels. If these plaques tear off the vessel wall, the wall is injured and a blood clot (thrombus) closes the tearing site. This wound closure narrows the vessel or displaces it completely, resulting in reduced blood flow to the downstream organ, the heart.
The main risk factors for the occurrence of atherosclerosis of the coronary arteries and a subsequent heart attack are Further risk factors for a coronary artery disease or a myocardial infarction are
- Cigarette Smoking
- High blood pressure (arterial hypertension)
- A high total cholesterol level in the blood
- A low level of HDL cholesterol, which has a protective effect on the condition of the blood vessels
- A high level of lipoproteins-a in the blood
- Age (men over 45 years and women over 55 years have an increased risk of heart attack)
- A diabetes mellitus and
- The occurrence of CHD and/or heart attacks in first-degree relatives
- Overweight (Adiposity)
- Physical inactivity
- Wrong diet
- Lipometabolic disorders
- Glucose tolerance disorder with elevated blood sugar levels and
- Tendency to thrombosis (vessel occlusion tendency)
Much rarer causes of a heart attack (less than 5% of cases) are vascular inflammation (vasculitis), embolisms (thrombi carried into the bloodstream), (congenital) vascular malformations existing since birth, and vascular spasms that can be caused by medication. Factors that can be partly responsible for the occurrence of a heart attack are, in addition to physical exertion and mental stress, the time of day and the pre-existence of unstable angina pectoris.If angina pectoris symptoms have already occurred in the patient’s medical history, i.e. a feeling of tightness in the chest, sometimes with shortness of breath (dyspnoea) and reduced performance, the risk of a heart attack is 20%. The frequency (incidence) of a heart attack is increased in the early hours of the morning, as the blood tends to form thrombi (vascular occlusion).
In 70% of cases, the left half of the heart is affected by an infarction. It is larger and more muscular than the right half and therefore requires more oxygen. Myocardial infarction is further classified into transmural and non-transmural infarction.
In transmural myocardial infarction, more than 50% of the wall thickness of the heart muscle is affected by cell death and is associated with visible changes in the echocardiogram (ECG). In non-transmural myocardial infarction, the cell damage is limited to the inner layer of the heart wall and no correlate is found in the ECG. The part of the heart muscle that becomes functionless due to myocardial infarction depends on the location of the vascular occlusion.
If the narrowing or occlusion of the vessel is located at the vascular trunk, large areas of the heart muscle are undersupplied, resulting in an extensive infarction zone with a high loss of function. The longer the ischemia time (time in which the heart muscle is less supplied with oxygen), the more pronounced the process of cell death and the more severe the impairment of cardiac performance. Arterial hypertension (high blood pressure) is a widespread disease in the population of industrialized nations.
The high blood pressure can cause turbulence within the vessels. This promotes the deposition of various substances on the vessel wall. The deposits lead to more turbulence and even more substances being deposited.
In a sense, a vicious circle is present, because the substances constrict the vessel and lead to higher blood pressure values, which gradually put more and more stress on the heart. These deposits are particularly dangerous with regard to a heart attack if they occur in the coronary arteries. These vessels are responsible for supplying the heart muscles with oxygen and other nutrients.
Over time, constriction can lead to too little blood with nutrients reaching the heart muscle cells. This can result in damage or even death of the cells, which can lead to a heart attack. Blood pressure can also provide important information when the heart attack occurs acutely.
The heart can be so badly damaged by the infarction that it no longer has enough strength to maintain the blood pressure. A sharp drop in blood pressure (often accompanied by dizziness or fainting spells) can therefore be a sign of a heart attack. It has long been known that prolonged stress can have a damaging effect on the cardiovascular system.
There are several mechanisms behind this. On the one hand, chronic stress increases blood pressure and pulse rate in the long run. Especially high blood pressure values increase the risk to suffer a heart attack.
In addition, the body produces more white blood cells under stress. In stressful situations, these are supposed to help the immune system in particular to defend itself against foreign substances. The white blood cells do not only have positive effects on the body. Especially in people who already suffer from atherosclerosis (calcification of the vessels), these blood cells like to form additional plaques and deposits inside the vessels, thus leading to additional narrowing.
