Why does a heart suddenly stop beating?

Heart failure is a serious and feared complication of many heart diseases. Every year in Germany alone, more than 100,000 people die from this complete loss of heart function, whereby improved early defibrillation as part of first aid measures could significantly reduce the mortality rate. And the high number of cases of heart failure could also be significantly reduced in prevention.

The heart: structure and function

The heart (Cor) is the motor of our body. As the centre of the blood circulation, it is, besides the brain, the most important organ for maintaining vital functions. Of course, the pumping property of the heart muscle is essential, thanks to which the blood is conducted through the blood vessels through the entire body.

One of the various tasks of the cardiovascular system is to pump the blood through the blood vessels:

Oxygen transport – Regular breaths enrich the blood in the lungs with oxygen. This oxygen then passes through the blood circulation into all areas of the body and supplies organs and tissue structures with the necessary “fresh air”.

Nutrient transport – Nutrients that pass into the metabolism in the gastrointestinal tract through digestive processes are also largely transported via the blood. Vitamins and minerals, proteins and carbohydrates can therefore quickly reach their place of use in the body thanks to their nutrient-conducting function.

Metabolism – Many metabolic waste products are also removed from the body via the blood circulation. Thus urinary substances in the kidneys are filtered out of the blood and carbon dioxide, which is produced in the organs after the consumption of oxygen, is breathed out of the venous blood in the lungs.

Immune defence – The cells contained in the blood also include white blood cells, the so-called leukocytes. These have a special role to play in the immune function, as they either detect harmful foreign bodies such as infectious agents and pass the relevant information on to the immune defence, or are themselves involved in the defence because they produce specific antibodies against the body invaders.

Hormone transport – Hormones are an important component in signal transduction for certain bodily functions. By distributing hormones through the bloodstream in the body, the heart also has an internal “communication function” that controls hormone-based mechanisms.

Heat regulation – The heart is also involved in the development of body temperature. This is because blood circulation continuously cools the body and defuses local heat sources.

The pumping function of the heart comes about through regular muscle contractions of the heart muscle. The clock for this is the so-called sinus node (Nodus sinutrialis). This is located in the right atrium and is controlled by the sympathetic and parasympathetic nodules. The impulses of the sinus node are transmitted to the entire heart muscle via the atrioventricular node (Nodus atrioventricularis, short: AV node), a muscular connecting piece between the left and right ventricles.

The result is regular muscle contractions of the heart, which are perceived as heart beats. This special control of the heart rhythm and radial pumping mechanism is also known in medicine as the excitation conduction system.

Definition Heart failure

Heart failure now describes the functional failure of this system of excitation conduction and pump function. This condition, which can be triggered by various heart diseases, is always life-threatening.

Doctors distinguish between two main forms of heart failure:

Acute heart failure – heart failure occurs suddenly and without any prior warning.

Chronic heart failure – heart failure develops insidiously and progresses along with an increasing deterioration of heart function.

If the failure of the heart is treated in time, the heart function can be restored. However, it often takes only a few minutes to decide whether the conduction of the heart’s excitation can be “retrieved” or whether it will dry up forever, resulting in cardiac death.

Causes of acute heart failure

Acute heart failure can have many causes and is always a life-threatening situation. Often the symptoms are completely absent or occur only so shortly before the onset of unconsciousness that the affected person and his or her environment are completely surprised by the event and are accordingly overwhelmed with the situation. For this reason one speaks here also of sudden heart failure and/or sudden heart death, if any assistance remains unsuccessful.

Cardiovascular diseases as the main cause

The triggers are usually to be found in an (undiscovered) disease of the heart. By far the most common cause is severe calcification of the coronary arteries. The clinical picture is known in medical circles as coronary heart disease and is often the result of a previous arteriosclerosis (arteriosclerosis), which is already very advanced.

The calcification process is gradual and therefore often remains undetected until acute heart failure occurs. Other cardiovascular diseases can also lead to acute heart failure. These include

These diseases, if left untreated, are often associated with premature heart damage, which further increases the risk of acute heart failure. In addition, there are a number of other influencing factors that promote such a scenario. If, for example, the heart is preweakened by a previous heart attack, the patient must continue to be monitored in hospital for a while to ensure that the heart attack is not followed by another life-threatening loss of heart function.