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Antiarrhythmic drugs

Normalizing effect on the disturbed rhythm of heart contractions may
render substances belonging to different classes of chemical compounds and
belonging to various pharmacological groups.
So, with arrhythmias associated with emotional stress in patients
without serious heart disease, an antiarrhythmic effect can have
sedative (sedative, tranquilizing) drugs. Antiarrhythmic
A number of agents affecting efferent and afferent
innervation (anticholinergic and cholinomimetics (see Atropine, Carbacholine.),
adrenergic blockers and adrenergic agonists (see - Adrenergic blockers, Izadrin), local
anesthetics (see Lidocaine, Trimecaine, Pyromecaine), some antiepileptic drugs
ttic drugs (see. Diphenin), 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
the property of which is a normalizing effect on the heart rhythm with
different types of arrhythmias. These funds, as well as a number of Ab-blockers,
calcium ion antagonists, lidocaine and other local anesthetics,
vasoconstrictor drug diphenin in connection with their pronounced antiarrhythmic
activity unite in the K group of antiarrhythmic drugs.
There are various classifications of antiarrhythmic drugs.
Currently, the most common classification is Vogen-William-
CA (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 repolarization (the main idea is
supreme amiodarone; Sympatholytic Ornids, or Brethil, are also included here);
U IV group - calcium channel blockers (antagonists of calcium ions).
The first group includes a number of drugs that differ in some particular
the penalties of action. It is conditionally divided into 3 subgroups:
Subgroup IA - quinidine, procainamide, disopyramide;
subgroup IB - local anesthetics (lidocaine, trimecaine, pyromecaine),
as well as mexiletine and diphenin;
subgroup IC - aymalin, ethmosin, ethacyzin, allapinin.
Some antiarrhythmic drugs have one degree or another.
properties of various subgroups.
Choosing an antiarrhythmic drug for optimal use
some form of arrhythmia requires knowledge of not only the nature of the arrhythmia, but also
the mechanism of action of the drug, the amount of its pharmacological properties.
The leading role in the mechanism of action of all antiarrhythmic drugs
plays an effect on cell membranes, on the transport of ions through them (Na +,
K +, Ca2 +), as well as the interconnected effect on electrophysiological
processes in the myocardium, on the depolarization of the electric membrane
cardiomyocyte potential.
Different groups of antiarrhythmic drugs and individual drugs are different
They are known for some types of influence on these processes. So, the drugs are subgroup-
Pipes IA and IC mainly inhibit the transport of sodium ions through "fast"
sodium channels of the cell membrane. Preparations of subgroup IB increase
membrane permeability to potassium ions. Quinidine concurrently with depression
transport of sodium ions reduces the intake of ion in cardiomyocytes
calcium. The same combined effect has a new antiarit
Bonnecor medicine.
Group I drugs reduce the maximum depolarization rate, increasing
decrease the excitability threshold, slow down the conductivity of the bundle of His and fibers
Purkinje, slow the restoration of the reactivity of the membranes of cardiomyocytes.
Group II drugs (Ab-blockers) reduce the effect on the heart
adrenergic impulses, which under certain conditions may have
importance in the pathogenesis of arrhythmias. In the mechanism of antiarrhythmic action of these
drugs a certain role is played by the suppression under their influence of activation
cell membrane adenylate cyclases and a decrease in the formation of cyclic
AMP, promoting the transmission of the effects of catecholamines. Preparations of this
groups reduce the transmembrane transfer of sodium ions, increase the trans-
nose of potassium ions, reduce the excitability of myofibrils and Purkinje fibers,
reduce the rate of excitation. Most A b -adrenoblock-
tori slow down the sinus rhythm, sinoatrial and atrioventricular
conductivity, have a negative inotropic effect.
Unique in its impact is the main representative of the pre-
group III paraths - amiodarone, which increases the duration of
action potential, slows down the conduction of an impulse in all areas of the
heart system, reduces sinus rhythm, causes lengthening of the inter-
shaft Q - T. It does not significantly affect the contractility
myocardial property. Amiadarone has a wide range of antiarrhythmic effects.
action and at the same time is an active antianginal drug.
The ornids (bretilia) attributed to group III have mainly
patholytic effect (see. Ornid), thus limiting the effect
catecholamines on the myocardium; however, it increases, like amiodarone,
duration of action potential.
Group III drugs have relatively little effect on the transmembrane
ion transfer.
Group IV drugs (verapamil, nifedipine, etc.) inhibit slow
transmembrane current of calcium ions into myocardial cells, which
reduces the automatism of ectopic foci and affects repeated
excitation input.
Features of the mechanism of action of drugs of various groups are important
importance to clarify the indications and contraindications in the appointment
one or another antiarrhythmic drug.
When choosing a drug, one should take into account not only its specific
antiarrhythmic features, but also general pharmacological properties
(effect on other functions and systems of the body), as well as possible side effects
effects.
It must be borne in mind that antiarrhythmic drugs in connection with their action
effect on the conduction system of the heart under certain conditions can
proarrhythmic (arrhythmogenic) action.

Subgroup Antiarrhythmic drugs includes subgroups: