The human heart has a relatively small size in comparison with the work that it performs. It pumps through the vessels an average of 4.7 liters of blood every minute, or 282 liters every hour, supplying organs and tissues with oxygen. Violations of frequency, rhythm and sequence of excitation and contraction of the heart are called cardiac arrhythmia.

The heart has two upper chambers, atria, and the two lower chambers, ventricles. The auricle pumps blood into the ventricles, then the right ventricle pumps blood into the lungs, while the left ventricle supplies blood to all the organs of the body. Genesis of rhythmic contractions of the heart is due to electrical impulses coming from the “natural stimulator”, i.e. the sinoatrial node. Each impulse passes through the atria to the atrioventricular (Aschoff-Tawara) node, and then to the ventricles. After the contraction, a pause occurs until the next impulse, during which the heart “rests.” The normal heart rate is 60 to 80 beats per minute in a calm state, with increasing activity, the frequency of contractions increases.

Cardiac arrhythmia and its signs

Heart arrhythmia (from Greek arrhythmia, lack of rhythm, irregularity of rhythm)


With some diseases (coronary heart disease, heart attack, cardiomyopathy, congenital heart disease), normal heart activity may be disrupted. Heart arrhythmia appears. Excessively frequent cardiac contractions are called tachyarrhythmia. One of the varieties of tachyarrhythmia is ventricular tachycardia, in which electrical impulses arise in the heart ventricles.

Ventricular tachycardia is one of the life-threatening rhythm disturbances. With excessively frequent contractions, the ventricles of the heart fail to fill up with enough blood. As a result, an insufficient amount of blood goes to the organs, including the brain. In addition to palpitation, a person can feel weakness, dizziness, a loss of consciousness is possible.

Chaotic unstable contractions of muscle fibers are called fibrillation, which, in turn, leads to cardiac arrest. This is the most dangerous complication of ventricular tachycardia, which requires immediate resuscitation. Heart failure, as a rule, occurs suddenly. To restore the normal heart rhythm, immediate defibrillation, an electrical impulse restoring the normal rhythm of the heart, is essential.

Unfortunately, this procedure is not always possible in the first minutes of the heart arrest. Therefore, the implantable ICD has a built-in defibrillator and an electronic heart stimulator. Defibrillator brings the heart out the state of ventricular tachycardia or fibrillation by stimulation or electrical impulses.


With certain diseases, the heart beats too slowly. Such violations of the heart rhythm are called bradycardia. With bradycardia, the volume of blood going to the organs is insufficient. The symptoms are dizziness, weakness, a feeling of lack of air, fainting.

Bradycardia can occur when sino-atrial node malfunction or heart block, when impulses from the S-A node to the ventricles are impaired. With bradycardia, the implantable ICD restores the normal heart rate. The volume of blood going to the organs is normalized, the symptoms of bradycardia are eliminated.