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Cardiac fibrillation is one of the so-called tachycardiac arrhythmias. These are characterized by the fact that the heart rate rises to over 100 beats per minute. 70 to 75 beats per minute would be normal for women and 60 to 70 beats per minute for men. Cardiac fibrillation is divided into atrial fibrillation and ventricular fibrillation.
When the heart rate rises
As the heart rate increases, less blood is pumped into the circulation per heartbeat. This is because the chambers do not have enough time to relax and refill, or the heart contractions are too weak and uncoordinated.
Atria and chambers
The human heart consists of four inner courtyards, two on each side of the heart: a small, somewhat muscle-free atrium that collects blood from the body or lungs, and a muscular chamber that sucks the blood out of the atrium and then back into the Body, or pressed into the pulmonary circulation. Simply put, the atria contract first, blood flows into the chambers of the heart and then the chambers contract and the blood is pumped into the circulation. All of this is coordinated by special heart cells. Their task is to transmit electrical signals to the ventricles in a certain order, in such a way that smooth cooperation is guaranteed.
With cardiac fibrillation, here atrial fibrillation, this process is disturbed. Effective atrial contractions can no longer take place. On the contrary - the atria resemble a “twitch” or “flicker”. In this way they can no longer properly help the chambers with the pumping work.
The atrial fibrillation
With atrial fibrillation, a cardiac arrhythmia, the atria contract between 350 and 600 times. These completely irregular actions are passed on to the chambers, which then also work in an uncontrolled manner. This means that the excitations of the atria only partially or not at all reach the chambers. This reduces the amount of blood that the chambers pump into the blood vessels. At rest, the amount of blood decreases by about fifteen percent, even more during physical activity. This is then noticeable through palpitations, rapid heartbeat and especially shortness of breath.
Atrial fibrillation is often not noticed at all and its effects are therefore underestimated. In contrast to ventricular fibrillation, this type of cardiac fibrillation is not life-threatening. If atrial fibrillation occurs like a seizure, this is usually only for a short time and is either not perceived as such or, as already mentioned, described as heart stumbling or palpitations. Weakness, shortness of breath, heartache and fear are among the complaints. The faster the heart beats, the sooner patients will notice and the more uncomfortable it will be for them.
Possible causes of atrial fibrillation include high blood pressure that has persisted for a long time, old age, heart failure, diabetes mellitus, coronary artery disease, hyperthyroidism, a heart valve defect, and excessive alcohol consumption.
A complication of cardiac fibrillation, especially atrial fibrillation, is thrombus formation (formation of blood clots). If these dissolve, they can cause an arterial embolism in the form of a stroke or a circulatory disorder in another organ. In addition, the risk of stroke increases with age. If the fibrillation has existed for a long time, the atria become larger and change their actual tissue structure. There is also a risk of heart failure. Most of those affected live with symptoms such as palpitations and shortness of breath during physical exertion for years. There is also a pulse deficit. This means that not all pulse waves emanating from the heart arrive in the periphery, for example in the hand or foot artery. In practice, this can be determined by pressing the various pulses.
In the case of cardiac fibrillation, a specialist, a so-called cardiologist, should generally be consulted. This feels the pulses and auscultates the heart. Usually, an EKG (electrocardiogram) is also included. Such an EGK does not necessarily have to be abnormal. Especially when the atrial fibrillation is in the initial phase, a long-term ECG that is applied between 24 and 48 hours is more meaningful. Another option is to use an event recorder. This is activated by the patient whenever complaints arise. The doctor then evaluates the results using a computer.
In order to counteract clot formation, a complication in cardiac fibrillation, the patient is usually prescribed a drug that inhibits blood clotting (anticoagulants). A so-called drug cardioversion is carried out against the rhythm disorders, which means that those affected are prescribed an antiarrhythmic drug. Another option is electrical cardioversion. It tries to restore the normal heartbeat. This therapy is reminiscent of an “electric shock” during short anesthesia. Before it is used, however, it must be ensured that no blood clot has formed in the atria of the patient. This is checked using a special ultrasound process.
Another treatment option is catheter ablation. This is a procedure in which a certain area in the left atrium is obliterated by means of high-frequency current or cold with the help of a catheter that is pushed over the groin through the vena cava to the heart.
With the so-called frequency control, an attempt is made to lower the pulse rate at rest. This is done by giving medication, such as beta-blockers. This is a therapy procedure for the elderly, with less discomfort.
The ventricular fibrillation
Ventricular fibrillation is a life-threatening fibrillation. If left untreated, this can lead to cardiovascular arrest within a short time. With ventricular fibrillation, the ventricles contract between 350 and 600 times per minute. Controlled ventricular contraction is no longer possible, which means that very little blood is ejected into the vessels. Emergency therapy with resuscitation / defibrillation must be done as soon as possible.
With ventricular fibrillation, the special heart cells are still involved, but the contractions are no longer harmonious, causing the heart muscle to “shake” or “flicker”. A normal contraction is no longer possible and therefore the ventricle no longer pumps the blood properly. If the help does not come in time, a so-called asystole develops - the heart stops.
The most common cause of ventricular fibrillation is damage to the heart muscle caused by coronary artery disease (CHD) or by an acute heart attack. Other causes include myocarditis (inflammation of the heart muscle), severe heart failure (heart failure) or a disease of the cardiac conduction system. Potassium and magnesium are extremely important for the proper functioning of the heart. If the composition of these two vital minerals is very changed, this can also be a reason for life-threatening cardiac fibrillation. Especially when patients with heart failure are taking medication for drainage, the blood should be checked closely for the minerals.
A power accident can also cause ventricular fibrillation. Patients who have had ventricular fibrillation in their lifetime are at high risk of repeating this.
Unconsciousness occurs within a few seconds - without a pulse and without breathing. This can happen out of the blue without a harbinger. Possible warning signs are the following: chest pain on the left side, dizziness, fainting spells, shortness of breath even with little exertion and palpable palpitations. All of these symptoms urgently need to be cleared up by a doctor. Chest pain, tightness in the chest, fear of death, shortness of breath - an emergency doctor must be called here.
The ECG makes ventricular fibrillation visible. Irregular spikes and a frequency of more than 320 beats per minute are typical indications here
With ventricular fibrillation, every second counts. Resuscitation measures must be initiated immediately. The faster ventricular fibrillation is interrupted with a defibrillator, the greater the chance of survival. If patients are at high risk for this threatening cardiac fibrillation and treatment with medication is unsatisfactory, a defibrillator may be implanted. This detects a ventricular fibrillation and interrupts this with an electric shock. (sw)
Author and source information
This text corresponds to the specifications of the medical literature, medical guidelines and current studies and has been checked by medical doctors.
- Thomas Lambert, Clemens Steinwender: Cardiovascular Medicine, Trauner Verlag, 1st edition, 2019
- L. Brent Mitchell: Atrial Fibrillation (AF), MSD Manual, (accessed September 2, 2019), MSD
- Thomas Paul et al .: Guideline Pediatric Cardiology: Tachycardia Cardiac Arrhythmias in Childhood, Adolescence and Young Adulthood (EMAH Patients), German Society for Pediatric Cardiology, (accessed 02.09.2019), AWMF