Supraventricular tachycardia
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Description:
Supraventricular tachycardias (NZhT) – the umbrella term designating set of atrial and atrioventricular tachycardias. Except for antidromic tachycardia at a syndrome of WPW, atrial and atrioventricular tachycardias with blockade of one of ventriculonector branches, and also atrial tachycardias in the presence of additional ways of atrioventricular carrying out (DPP), they have the narrow QRS complexes (less than 0,12 sec.).
Supraventricular tachycardias take the intermediate place between potentially lethal and high-quality disturbances of a cordial rhythm. In most cases the forecast at them good.
Symptoms of Supraventricular tachycardia:
Clinical manifestations depend on rhythm frequency, predserdno ventricular synchronization (at simultaneous reduction of auricles and ventricles the hemodynamics is broken more considerably) and tachycardia duration.
Paroxysmal form — an attack of frequent heartbeat. Begins suddenly, is followed by the expressed concern, weakness, an asthma, pain in a breast or stenocardia. The expressed tachycardia is followed by decrease in the ABP. The frequent and plentiful urination is characteristic. Duration of an attack is various: of several seconds till several o'clock and days, At 20% of patients attacks of tachycardia are interrupted spontaneously.
The chronic (constant and returnable) form without treatment proceeding for years leads to an aritmogenny dilatatsionny cardiomyopathy and heart failure.
Reasons of Supraventricular tachycardia:
The Bouveret's Supraventricular Diseases (BSD) arise at patients of all age groups, however at young patients without the accompanying SSZ their emergence is caused by existence of the functioning additional conduction paths. In the senior age groups Bouveret's supraventricular diseases arise owing to disturbance of functioning of the AV-node. According to recommendations of ACC/AHA/ESC 2003, in the NZhT group carry AV-uzlovuyu reciprocal tachycardia and AV-retsiproknuyu tachycardia with participation of additional conduction paths.
Treatment of Supraventricular tachycardia:
The choice of drug for stopping of PNT is defined by width of the QRS complexes.< 120 мс, диагностируется «узкая» ПНТ. Если длительность комплексов QRS > Lasting 120 ms, is carried out differential diagnosis between "wide" supraventricular and ventricular tachycardia. Pharmacological properties of a propafenon allow to use this drug for stopping of PNT with narrow complexes (recommendations of ACC/AHA/ESC 2003 - a class of the proof of IIA).
Efficiency of stopping of PNT by means of a propafenon depends on a type of a tachyarrhythmia, character of a basic disease and existence of additional ways of AV-carrying out. The greatest efficiency of use of a load dose of a propafenon is noted when stopping PNT from AV-connection. Also Propafenon can be recommended for stopping and prevention of NT at patients with WPW syndrome as it slows down anterograde carrying out on additional conduction paths. High performance of drug is found at treatment of tachycardias with the short refractory period of anterograde carrying out.
Meta-analysis which results were published in 1998 became one of the largest researches studying efficiency of a propafenon in stopping and prevention of paroxysms of PNT. The analysis included 1 843 patients with supraventricular tachycardias, duration of observation of which made over a year. As a result of a research it was found out that preventive reception of a propafenon allowed to keep a sinoatrial rate more than at 60% of patients within a year, at the same time side effects of therapy were registered extremely seldom.
Thus, good tolerance of a propafenon and convenience of use of its peroral load dose allow to recommend it both for stopping of paroxysms of NZhT, and for their prevention.
For stopping reception of a load dose of 450 mg is most often used.
For prevention пропафенон 3 times a day are appointed in a dose of 150 mg.
