Ventricular tachycardia
Last reviewed: 23.04.2024
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Ventricular tachycardia consists of three or more consecutive ventricular pulses with a frequency of 120 per minute.
The symptoms of ventricular tachycardia depend on the duration and vary from a complete lack of sensation and palpitations to hemodynamic collapse and death. The diagnosis is established according to an electrocardiogram. Treatment for ventricular tachycardia, with the exception of very short episodes, includes cardioversion and antiarrhythmic drugs, depending on the symptoms. If necessary, prescribe long-term treatment with the use of an implantable cardioverter-defibrillator.
Some experts use the value of 100 contractions per minute as a limit for ventricular tachycardia. Repeated ventricular rhythm with less frequency is called enhanced idioventricular rhythm, or slow ventricular tachycardia. This condition is usually benign and does not require treatment until hemodynamic symptoms appear.
Most patients with ventricular tachycardia have significant cardiac abnormalities, mainly myocardial infarction or cardiomyopathy. Electrolyte abnormalities (especially hypokalemia or hypomagnesemia), acidosis, hypoxemia, and side effects of drugs may also contribute to the development of ventricular tachycardia. The syndrome of an extended QT interval (congenital or acquired) is associated with a special form of ventricular tachycardia, called “pirouette” tachycardia (torsades depointes).
Ventricular tachycardias can be monomorphic or polymorphic, stable or unstable. Monomorphic ventricular tachycardia arises from a single abnormal focus or an additional pathway and is regular with the appearance of identical QRS complexes . Polymorphic ventricular tachycardia arises from several different foci or pathways and is irregular, with differing QRS complexes . Unstable ventricular tachycardia lasts <30 s, sustained - 30 s or stops faster due to the development of hemodynamic collapse. Ventricular tachycardia often turns into ventricular fibrillation followed by cardiac arrest.
Symptoms of ventricular tachycardia
A short ventricular tachycardia or ventricular tachycardia with a low frequency may be asymptomatic. Sustained ventricular tachycardia almost always leads to the development of prominent symptoms, such as rate, palpitations, signs of hemodynamic insufficiency, or sudden cardiac death.
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Diagnosis of ventricular tachycardia
The diagnosis is made according to ECG. Any tachycardia with a wide ventricular complex (QRS 0.12 s) should be regarded as ventricular tachycardia until it is proven otherwise. The diagnosis is confirmed by detecting on the electrocardiogram dissociation of the P waves , stretched or trapped complexes, unidirectionality of the QRS complex in the chest leads (concordance) with the discordant T wave (directed against the direction of the ventricular complex) and the frontal direction of the QRS axis in the northwest quadrant. Differential diagnosis is carried out with supraventricular tachycardia, combined with the blockade of the bundle of the bundle of His or with an additional way of conducting. At the same time, since some patients are surprisingly well tolerated with ventricular tachycardia, the conclusion that a well-tolerated wide ventricular complex tachycardia should be supraventricular is an error. The use of drugs used in supraventricular tachycardia (for example, verapamil, diltiazem) in patients with ventricular tachycardia can lead to hemodynamic collapse and death.
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Treatment of ventricular tachycardia
Emergency treatment of ventricular tachycardia. Treatment depends on the symptoms and duration of ventricular tachycardia. Ventricular tachycardia with arterial hypertension requires synchronized direct cardioversion with a strength of 100 J. Stable, stable ventricular tachycardia can be treated with intravenous drugs, usually lidocaine, which quickly acts, but is quickly inactivated. With the ineffectiveness of lidocaine, procainamide can be administered intravenously, but the administration can take up to 1 hour. The ineffectiveness of procainamide serves as an indication for cardioversion.
With unstable ventricular tachycardia, there is no need for emergency treatment until the contractions become very frequent or the seizures are long enough to cause symptomatology. In such cases, prescribe antiarrhythmic drugs, as with sustained ventricular tachycardia.
Long-term treatment of ventricular tachycardia
The main task is to prevent sudden death, rather than simply suppressing arrhythmia. This is best achieved by implanting a cardioverter-defibrillator. At the same time, deciding who to treat is always difficult and depends on identifying potentially life-threatening ventricular tachycardias and the severity of underlying cardiac disease.
Prolonged treatment is not used if the identified attack of ventricular tachycardia is a result of a transient (for example, 48 hours after the development of myocardial infarction) or reversible (disorders associated with the development of acidosis, electrolyte imbalance, poruritmic effect of antiarrhythmic drugs) causes.
In the absence of a transient or reversible cause, patients who have had an attack of sustained ventricular tachycardia usually need ICDF. Most patients with sustained ventricular tachycardia and severe structural heart disease should also receive beta-blockers. If the use of ICDF is not possible, amiodarone should be the preferred anti-arrhythmic drug to prevent sudden death.
Since unstable ventricular tachycardia is a marker for an increase in the risk of sudden death in patients with structural heart disease, such patients (especially with an ejection fraction less than 0.35) need further examination. There is evidence of the need to implant ICDF in such patients.
If prevention of VT is necessary (usually in patients with ICDF suffering from frequent episodes of ventricular tachycardia), antiarrhythmic drugs, radiofrequency or surgical ablation of arrhythmogenic substrates are used. Can use any antiarrhythmic drug la, lb, lc, II, III classes. Since b-blockers are safe, in the absence of contraindications, they become the means of choice. If another drug is needed, sotalol is prescribed, then amiodarone.
Radiofrequency ablation is often performed in patients with ventricular tachycardia with clearly detectable sources [for example, ventricular tachycardia from the right ventricular outflow tract, left septal ventricular tachycardia (Belassen's ventricular tachycardia, verapamil-sensitive ventricular tachycardia)