Antiarrhythmic drugs

Normalizing effect on the disturbed rhythm of cardiac contractions can
Substances belonging to different classes of chemical compounds and
Belonging to different pharmacological groups.
Thus, in arrhythmias associated with emotional stress, in patients
Without serious heart disease antiarrhythmic effect may have
Calming (sedative, tranquilizing) drugs. Antiarrhythmic
A number of agents that affect the efferent and afferent-
(Holinoblokatory and holinomimetiki (see Atropin, Karbacholin.),
Adrenoblockers and adrenomimetics (see -Arenoblockers, Iadrin), local
Anesthetics (see Lidocaine, Trimecaine, Pyromecaine), some antiepileptic-
(See Diphenin), preparations containing potassium salts (see Diphenin).
Potassium chloride, Asparcum, Panangin), calcium ion antagonists (see Verapamil,
Nifedipine), etc.
At the same time, there are a number of drugs, the main pharmacological
The property of which is the normalizing effect on the heart rhythm at
Different types of arrhythmias. These drugs, as well as a number of Ab-adrenoblockers,
Antagonists of calcium ions, lidocaine and other local anesthetics, anti-
An anticonvulsant preparation of diphenin in connection with their severe antiarrhythmic
Activity is combined into a group of antiarrhythmic drugs.
There are different classifications of antiarrhythmic drugs.
Currently, the most common classification of Vaughan-William-
Sa (Vahoun-Williams EM), which subdivides antiarrhythmics into 4 groups:
UI group - membrane-stabilizing agents (quinidinoids);
UII group - A b-adrenoblockers;
U III group - drugs that slow repolarization (main
Amiodarone; Here the sympatholytic ornid, or brethilia, is also included);
U IV group - calcium channel blockers (calcium ion antagonists).
The first group includes a number of drugs that differ in some
Actions. Conditionally it is divided into 3 subgroups:
Subgroup IA - quinidine, novocainamide, disopyramide;
Subgroup IB - local anesthetics (lidocaine, trimecaine, pyromecaine),
As well as mexiletine and diphenine;
Subgroup IC - aymalin, etmozin, etatsizin, allapinin.
Some antiarrhythmic drugs have to some extent
Properties of different subgroups.
The choice of an antiarrhythmic agent for optimal use with that
Or other form of arrhythmia requires knowledge of not only the nature of the arrhythmia, but also the me-
The effect of the drug, the amount of its pharmacological properties.
In the mechanism of action of all antiarrhythmic drugs, the leading role
Plays an effect on cell membranes, on transport through them ions (Na +,
K +, Ca2 +), as well as the associated effects on electrophysiologists-
The processes in the myocardium, the depolarization of the electrical membrane
Potential of cardiomyocytes.
Different groups of antiarrhythmics and individual drugs
Some influences on these processes. Thus, preparations of subgroups
Ia and Ic mainly suppress the transport of sodium ions through "fast"
Sodium channels of the cell membrane. Preparations of subgroup IB increase
Permeability of membranes for potassium ions. Quinidine simultaneously with oppression
Transport of sodium ions reduces the flow into the cardiomyocytes of ions
Calcium. The same combined effect is exerted by the new anti-
Bonnecore.
Group I drugs reduce the maximum depolarization rate,
The threshold of excitability, slow the conductivity along the bundle and the fibers
Purkinje, slow down the restoration of reactivity of membranes of cardiomyocytes.
Group II drugs (Ab-adrenoblockers) reduce the effect on the heart
Adrenergic impulses that can under certain conditions have
Value in the pathogenesis of arrhythmias. In the mechanism of antiarrhythmic action of these
The suppression of activation under their influence plays a certain role
Adenylate cyclase of cell membranes and a decrease in the formation of cyclic
AMP, which promotes the transfer of effects of catecholamines. Preparations of this
Groups decrease the transmembrane transfer of sodium ions, increase the
Nose of potassium ions, reduce the excitability of myofibrils and Purkinje fibers,
Reduce the speed of excitation. The majority of A-b-adrenergic block-
Slow sinus rhythm, sinoatrial and atrioventricular
Conductivity, have a negative inotropic effect.
Unique in its impact is the main representative of the pre-
III group - amiodarone, which increases the duration of
The effect of the action, slows the holding of momentum across all
The cardiac system decreases the sinus rhythm, causes lengthening of the inter-
It does not have a significant effect on the contractile process.
The ability of the myocardium. Amiadarone has a broad spectrum of antiarrhythmic activity.
And at the same time is an active antianginal drug.
The ornid (brethilia), ranked as group III,
Pathological action (see Ornid), thus limiting the effect of
Catecholamines on the myocardium; At the same time, it increases, like amiodarone,
Duration of the action potential.
Preparations of group III relatively little influence on transmembrane
Ion transfer.
Preparations of the IV group (verapamil, nifedipine, etc.) inhibit slow-
Transmembrane current of calcium ions into myocardial cells, which is
It reduces the automatism of ectopic foci and affects the repeated
Excitation input.
The features of the mechanism of action of preparations of various groups have important
Value for clarification of indications and contraindications in prescribing
One or another antiarrhythmic drug.
When choosing a drug, one should take into account not only its specific
Antiarrhythmic features, but also the general pharmacological properties
(Influence on other functions and systems of the body), as well as possible side effects
Effects.
It is necessary to take into account that antiarrhythmic drugs in connection with their de-
On the conduction system of the heart can, under certain conditions,
Proaritmic (arrhythmogenic) action.