Arrhythmia (from Greek a is a negative particle and rythmos is a rhythm) is a violation of the normal sinus rhythm of heart contractions.
Conductive system of the heart. With each beat of the heart, there is a sequential reduction in its departments – first the atria, and then the ventricles. Abbreviations follow one after another at regular intervals. A clear and harmonious work of the departments of the heart provides its conductive system. It represents nerve fibers and plexuses along which excitation passes in a certain sequence to all parts of the heart. The signal for myocardial contraction, in essence, is a weak electrical impulse that is generated by special cells called a pacemaker. The impulse originates in the sinus node which is located at the top of the right atrium. It is he who regulates the heart rate (60–80 in 1 minute).
Next, a pulse is applied to the ventricles through the atrioventricular node , providing heart rate 40-60 1 minute, and then through the atrioventricular bundle (bundle branch block) and its legs, which generate pulses with a frequency of 20-40 min in 1 – a nerve endings ( Purkinje fibers ) to the muscle itself. If the sinus node fails completely, the heart will not stop, and the atrioventricular node will become the main pacemaker. And even with the blockade of this node, cardiac arrest will also not occur, because “Control” will be transferred to the atrioventricular bundle and Purkinje fibers . The functioning of the conduction system of the heart as a whole is influenced by the central nervous system, thyroid hormones and adrenal glands, which accelerate or slow down the electrical impulse and, accordingly, increase or decrease the heart rate.
Causes of arrhythmias.
- Expansion of the cavities of the heart (dilatation),
- An increase in myocardial mass ( myocardial hypertrophy) and insufficient oxygen supply to the heart muscle due to this,
- The development of connective (scar) tissue after a heart attack, myocarditis (inflammation of the heart muscle),
- Atherosclerotic narrowing of the coronary vessels.
- These changes are frequent companions of hypertension, coronary heart disease and heart defects.
- With hormonal disorders ( thyrotoxicosis
- A healthy person can provoke arrhythmia can be plentiful food, constipation , tight clothes, insect bites, some medications, stress.
- With uncontrolled use, drugs of almost all major groups, drugs to improve cerebral circulation ( cavinton , oxybral , etc. ) and even antiarrhythmic drugs themselves can cause arrhythmia.