Polymorphic ventricular tachycardia in children

Polymorphic ventricular tachycardia (catecholaminergic) is a malignant arrhythmia caused by the presence of ventricular tachycardia of at least two morphologies and induced by physical exertion or the introduction of isoproterenol. It is accompanied by syncope and has a high risk of sudden arrhythmic death. The familial variant of polymorphic catecholaminergic ventricular tachycardia is presumably considered a hereditary disease.

Symptoms of polymorphic ventricular tachycardia

Attacks of polymorphic ventricular tachycardia are provoked by emotional or physical stress, as well as swimming. In more than 30% of cases, syncope is accompanied by seizures, which causes late diagnosis. These patients, as well as patients with SYH QT, are monitored by a neurologist for a long time and receive anticonvulsant therapy. On the ECG outside the attack, as a rule, bradycardia and normal Q-Tc values are recorded. The reaction to the stress test is highly reproducible, and the test itself is key in diagnosing the disease, since it is highly likely to provoke polymorphic tachycardia in this group. Patients are characterized by a progressive increase in arrhythmic symptoms - from a single monomorphic ventricular extrasystole to bigeminy, polymorphic extrasystole and polymorphic ventricular tachycardia. In the absence of treatment, mortality from this disease is very high, reaching 30-50% by the age of 30. Moreover, the earlier the clinical manifestation of the disease occurs, the higher the risk of sudden arrhythmic death.

Treatment of polymorphic ventricular tachycardia

Beta-blockers [nadolol, bisoprolol (concor), atenolol, propranolol] are a mandatory component of drug therapy for patients with polymorphic tachycardia, they significantly reduce the risk of sudden death. The doses of these drugs should be 2 times higher than those prescribed to patients with CYH QT. The most effective drug is nadolol. Often, one antiarrhythmic drug is not enough. As a rule, only combined antiarrhythmic therapy is effective in such patients. Another antiarrhythmic drug is added to the beta-blocker, taking into account its possible effect on trigger factors, such as supraventricular arrhythmias. In young people, the following may be effective as a 2nd antiarrhythmic drug: mexiletine at a dose of 5 mg/kg per day, lappaconitine hydrobromide at a dose of 1 mg/kg per day, propafenone at a dose of 5 mg/kg per day, amiodarone at a dose of 5-7 mg/kg per day, verapamil at a dose of 2 mg/kg per day, or diethylaminopropionylethoxycarbonylaminophenothiazine (ethacizine) at a dose of 1-2 mg/kg per day. Carbamazepine may be effective in combination therapy in children for antiarrhythmic purposes. The selection of an antiarrhythmic drug is carried out under the control of ECG data and Holter monitoring, taking into account the saturation doses. It is advisable to calculate the maximum therapeutic effect of the drug taking into account the periods of the day when ventricular tachycardia is most pronounced. Exceptions are long-acting drugs and amiodarone. The maintenance dose of the antiarrhythmic drug is determined individually. If the Q-T interval increases by more than 25% of the initial value, class III drugs are discontinued. Metabolic therapy includes antihypoxants and antioxidants. ACE inhibitors are also used, improving hemodynamic parameters in chronic circulatory failure.

Development of syncopal attacks during therapy, critical sinus bradycardia limiting the possibilities of subsequent antiarrhythmic therapy, as well as persistence of a high risk of sudden arrhythmic death during treatment (assessed by the concentration of individual risk factors) are indications for interventional treatment. Implantation of a cardioverter-defibrillator is performed in children with syncopal variants of polymorphic ventricular tachycardia if antiarrhythmic therapy does not prevent the development of polymorphic ventricular tachycardia. When trigger factors for the development of ventricular tachycardia are identified, their control modes are connected in implanted devices (antitachycardia stimulation mode, etc.). In cases of severe recurrent ventricular tachycardia, the advisability of radiofrequency catheter ablation of the source of ventricular tachycardia or trigger arrhythmic zones should be discussed. Implantation is not performed in patients with frequent episodes of ventricular tachycardia or in the case of frequent episodes of supraventricular arrhythmia with a high rhythm rate (more than 200 per minute) in patients with ventricular tachycardia, since in this case unjustified triggering of the antiarrhythmic implanted device for supraventricular tachyarrhythmia is possible. In severe cases, it is necessary to use all possible resources of antiarrhythmic therapy (combined administration of nadolol and mexiletine); in recent years, the effectiveness of left-sided sympathectomy has been proven.

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