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Antiarrhythmic drugs

Normalizing effect on the disturbed rhythm of heart contractions can
provide substances belonging to different classes of chemical compounds and
belonging to different pharmacological groups.
So, with arrhythmias associated with emotional stress in patients
without serious heart disease, antiarrhythmic effects can have
sedatives (sedatives, tranquilizing) drugs. Antiarrhythmic
This activity has a number of agents that affect the efferent and afferent
inervation (anticholinergics and cholinomimetics (see Atropine, Carbacholine.),
adrenergic blockers and adrenergic mimetics (see - Adrenergic blockers, Izadrin), local
anesthetics (see Lidocaine, Trimecain, Pyromecain), some antiepilep-
tical preparations (see Difenin), preparations containing potassium salts (see
Potassium chloride, Asparkam, Panangin), calcium ion antagonists (see Verapamil,
Nifedipine) and others.
However, there are a number of drugs, the main pharmacological
a property of which is the normalizing effect on the heart rhythm at
different types of arrhythmias. These tools, as well as a number of Ab -blockers,
calcium ion antagonists, lidocaine and other local anesthetics,
convulsive drug difenin due to their pronounced antiarrhythmic
activity united in the K group of antiarrhythmic drugs.
There are various classifications of antiarrhythmic drugs.
Currently, the most common classification of Wogen-William
sa (Vaughan-Williams E. M.), dividing antiarrhythmics into 4 groups:
UI group - membrane stabilizing agents (quinidine-like);
UII group - A b -blockers;
U III group - drugs that slow down the repolarization (the main
Amiodarone; here they include the sympatholytic Ornid, or Bretilium);
U IV group - calcium channel blockers (calcium ion antagonists).
The first group includes a number of drugs that differ in some specific
the benedities of action. Conventionally, it is divided into 3 subgroups:
Subgroup IA - quinidine, novokinamid, disopyramide;
subgroup IB - local anesthetics (lidocaine, trimekain, pyromekain),
as well as mexiletin and difenin;
The IC subgroup is Aymaline, Etmozin, Etacizin, Allapinin.
Some antiarrhythmic drugs have to varying degrees.
properties of different subgroups.
The choice of antiarrhythmic agent for optimal use with
or another form of arrhythmia requires knowledge of not only the nature of the arrhythmia, but also the
the action of the drug, the sum of its pharmacological properties.
In the mechanism of action of all antiarrhythmic drugs leading role
plays an effect on cell membranes, on the transport of ions through them (Na +,
K +, Ca2 +), as well as the associated effect on electrophysiology
myocardial processes, depolarization of the electric membrane
cardiomyocyte potential.
Different groups of antiarrhythmic drugs and individual drugs of different
some kinds of influence on these processes. So, drugs subgroups
IА and IС spells mainly suppress the transport of sodium ions through “fast” ones.
sodium channels of the cell membrane. Preparations of subgroup IB increase
membrane permeability to potassium ions. Quinidine concurrently with oppression
transport of sodium ions reduces the entry of ions into cardiomyocytes
calcium. The same combined effect has a new anti-anti-inflammatory
Bonicore remedy.
The preparations of group I reduce the maximum rate of depolarization, increasing
the excitability threshold is slowed down, the conductivity of the His bundle and fibers is slowed down
Purkinje, slow down the recovery of cardiomyocyte membrane reactivity.
Preparations of group II (Ab -blockers) reduce the effect on the heart
adrenergic impulses that may under certain conditions have
significance in the pathogenesis of arrhythmias. In the mechanism of the antiarrhythmic action of these
drugs play a role suppression under their influence activation
adenylate cyclase cell membranes and reducing the formation of cyclic
AMF, contributing to the transmission of catecholamine effects. Drugs of this
groups reduce the transmembrane transfer of sodium ions, increase the
the nose of potassium ions, reduce the excitability of myofibrils and Purkinje fibers,
reduce the rate of excitation. Most A b -adrenoblock-
tori slow down sinus rhythm, sinoatrial and atrioventricular
conductivity, have a negative inotropic effect.
Unique in its effects is the main representative of
Paraty III group - amiodarone, which increases the duration of
action potential, slows down the conduct of the impulse in all areas of the wire.
heart system, slows sinus rhythm, causes lengthening of the inter-
shaft Q - T. It has no significant effect on contractile
myocardial property. Amiadarone has a wide range of antiarrhythmic effects.
however, it is also an active antianginal drug.
Belonging to the III group of ornids (bretilium) has mainly sym-
patolytic action (see Ornid), thus limiting the influence
catecholamines on myocardium; however, it increases, like amiodarone,
action potential duration.
Group III drugs have relatively little effect on transmembrane
ion transport.
Group IV drugs (verapamil, nifedipine, etc.) inhibit slow
transmembrane current of calcium ions in myocardial cells, which is
reduces the automaticity of ectopic foci and affects the repeated
input excitation.
Features of the mechanism of action of drugs of different groups are important.
value to clarify the indications and contraindications in the appointment
one or another antiarrhythmic drug.
When choosing a drug, it is necessary to consider not only its specific
antiarrhythmic features, but also general pharmacological properties
(influence on other functions and systems of the body), as well as possible adverse effects
effects.
It should be borne in mind that antiarrhythmic drugs due to their
effect on the conducting system of the heart can in certain conditions
vat proarrhythmic (arrhythmogenic) action.

Subgroup Antiarrhythmic drugs include subgroups: