COUNTERSHOCK

From Big Medical Encyclopedia

COUNTERSHOCK (synonym cardioversion) — a way of treatment of nek-ry disturbances of a cordial rhythm the impulse of electric current with energy of 50 — 100 J generated by the category of the condenser between two electrodes imposed on a chest wall of the patient. AA. t. apply to the termination of a Bouveret's disease, blinking and an atrial flutter, at to-rykh an impulse of current interrupts circulation of a wave of depolarization of a myocardium or suppresses the geterotopny center of excitement, and also for stopping of fibrillation of ventricles of heart (see the Defibrillation). Effect E. t. consists in recovery of a sinoatrial rate of heart.

For the first time E. t. it was applied in clinic by A. A. Vishnevsky, B. M. Zuckerman and S. I. Smelovsky in 1959; the method was widely adopted from 60th, especially after implementation in a design of defibrillators of the cardiosynchronizer combining an impulse with the QRS complex of the electrocardiogram that allows to avoid accidental coincidence on time of an electroimpulse to a so-called vulnerable phase of a cardial cycle, the corresponding top of a tooth of T of the electrocardiogram (see. Premature ventricular contraction ). Advantages E. t. in comparison with medicinal treatment of arrhythmias consist in its high performance (75 — 90% at a ciliary arrhythmia, apprx. 95% — die an atrial flutter, 75 — 95% — at various forms of a Bouveret's disease), immediate recovery after an electroimpulse of a sinoatrial rate (that is especially important in the presence of disturbances of a hemodynamics), and also lack of undesirable effect of antiarrhytmic drugs.

Indications to E. t. are fibrillation of ventricles of heart (see Arrhythmias of heart), a heavy Bouveret's disease (see) and paroxysms of blinking or an atrial flutter, and also a constant form of a ciliary arrhythmia (see) prescription up to 1 — 2 years, followed by heart failure and badly giving in to medicamentous therapy. At patients with paroxysmal disturbances of a heart rhythm E. t. it has to be carried out by that more urgently, than serious condition of the patient, especially in the absence of bystry effect of antiarrhytmic means or the increased danger of their use. Absolute contraindications to E. t. are not established. Do not recommend to apply E, as a rule. t. for elimination of a perpetual ciliary arrhythmia if it was preceded by the paroxysms of atrial fibrillation transferred the patient it is heavier, than a constant form, and also at short terms of preservation of the recovered sinoatrial rate in the past and at prescription of a ciliary arrhythmia of St. 2 years; at a total atrioventricular block (see the Heart block); at a syndrome of weakness of a sinus node (see. Bouveret's disease); at the heart diseases which are subject to operational treatment in the near future; at a cardiomegaly with the expressed heart failure; at the increased function of a thyroid gland before its suppression. At arrhythmias against the background of digitalis intoxication E. t. do not carry out if there are no vital indications, because of the increased danger of emergence of fibrillation of ventricles.

Emergency E. t. it is carried out without special training of the patient. At planned E. t. for several days cancel the cardiac glycosides appointed for reduction of a circulatory unefficiency; for the purpose of the prevention of the so-called normalizing thromboembolisms connected with a separation of the blood clots formed at arrhythmia in auricles owing to recovery of reductions of auricles some days before E. t. appoint anticoagulants, and for the purpose of decrease in probability of post-conversion arrhythmias of heart and a bystry recurrence of atrial fibrillation by the patient with a ciliary arrhythmia the day before give quinidine in a dose of 0,8 — 1,2 g a day (at a number of patients at the same time still to E. t. the sinoatrial rate is recovered). Planned E. t. it is carried out on an empty stomach.

For carrying out E. t. the patient is stacked on a back; electrodes of a defibrillator impose on a front chest wall (one of electrodes is pressed to a thorax in the right subclavial area, another — in the field of a top of heart) or have one over oblastyo hearts, and another — on spin (the effect is slightly higher at their perednezadny arrangement). By means of a special mark in the screen of an oscillograph synchronize an impulse of current with a tooth of R or S electrocardiograms. Before the category the patient is given an anesthesia, using short-range Thiopentalum-natrium, hexenal, diazepam, sometimes an electroanaesthesia, and carry out oxygenation through a catheter or a mask, stopping it at the time of the category of a defibrillator. The choice of energy of an impulse depends preferential on the nature of arrhythmia. At a ciliary arrhythmia at adults begin usually with 50 J, in the absence of effect repeat the category, having doubled energy of an impulse. During the carrying out E. t. according to the emergency indications sick with digitalis arrhythmias previously intravenously enter 100 mg of lidocaine; initial energy of an impulse at such patients makes 15 — 25 J. During the use of domestic defibrillators and not synchronized impulse tension of the first category makes 4000 in, and each of the subsequent — for 1000 in more (but not higher than 7000 in). AA. t. carry out with observance of all rules of a defibrillation at full readiness for resuscitation actions, including cardiostimulation (see). After E. t. appoint a maintenance therapy (quinidine, kordarony and other antiarrhytmic drugs) within several months.

Complications E. t. at observance of indications and the correct technology of its use are not numerous. Emergence of post-conversion disturbances of a cordial rhythm and conductivity is possible, to-rye connect with increase in a tone of sympathetic or parasympathetic parts of the nervous system under the influence of electric current. In the absence of cardiosynchronization the electric impulse can cause fibrillation of ventricles, is preferential due to coincidence to a «vulnerable» phase of a cardial cycle, a cut can take place approximately in 2% of cases. At its emergence immediately repeat the category with energy of an impulse of 200 J and more. Perhaps damaging action of an impulse on tissues of a thorax and heart, and temporary decrease in sokratitelny function of a left ventricle can lead to a fluid lungs in the first days. Normalizing thromboembolisms (in a brain, kidneys and other bodies) arise approximately at 1 — 1,5% of patients at any way of elimination of a ciliary arrhythmia; reception of anticoagulants reduces their number.

Bibliography: Syrkin A. L., Nedostup A. V. and Mayevskaya I. V. Electropulse treatment of arrhythmias of heart in clinic of internal diseases, M., 1970, bibliogr.; Mandel W. J. Cardiac arrhythmias, Philadelphia — Toronto, 1980.

A. L. Syrkin.

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