Daily Archive 29.12.2018

Signs of reciprocal AV-node tachycardia on ECG

Signs of reciprocal AV-node tachycardia on ECG

P teeth are layered on QRS complexes and therefore not visible. The QRS complex is narrow, the frequency of contractions of the ventricles is 150-200 per minute.

This form of supraventricular tachycardia occurs mainly in young people suffering from vascular dystonia. In people with heart disease, this form of heart rhythm disorder is quite rare.

The most common form of supraventricular tachycardia is reciprocal AV nodal tachycardia; A focus that initiates and maintains tachycardia is located above the level of the ventricles, in particular in the AV node.

It is believed that in the AV node, as a result of the so-called longitudinal dissociation, two pathways of excitation are formed: a slowly conducting, or alpha, path with a short refractory period and a fast conducting, or beta, with a long refractory period. Such splitting allows circular movement of the excitation wave when the excitation propagates from one path (alpha path) to another (beta path) and performs a fast circular motion.

At the analysis of an electrocardiogram the narrow QRS complexes, quickly following one after another, attract attention. The frequency of ventricular contractions is usually 120-220 per minute.

P teeth, although recorded, are negative and, due to the high frequency of contractions, are not visible or are not clearly visible. This results from the fact that teeth P are layered on the QRS complexes or are registered immediately after these complexes. The QRS and ST-T complexes do not initially change. Only with aberrant ventricular conduction, QRS complexes can be broadened, as in the blockade of the bundle of the His bundle (PG).

Accurately determining the boundaries of the P wave is sometimes difficult. Therefore, they used to speak simply about ‚Äúsupraventricular tachycardia‚ÄĚ, making no distinction between atrial and AV-nodal tachycardia.

It is noteworthy that this tachycardia often occurs in young people, especially in girls, suddenly, for no apparent reason or after exercise, and also stops suddenly. These features have important clinical significance. Reciprocal AV-nodal tachycardia can also occur in patients with a heart condition. However, in most cases, the general condition of the patients, despite the rapid reduction of the ventricles, remains relatively satisfactory, since the blood pressure, as well as the stroke and minute volumes of the heart, decrease slightly.

It is known that after an attack of reciprocal AV-nodal tachycardia, there is often abundant urination due to the release of atrial natriuretic peptide.

Treatment of reciprocal AV-node tachycardia often begins with carotid sinus massage, the patient is asked to strain (Valsalva maneuver), give him cold water to drink, if necessary, intravenously, verapamil, cardiac glycosides, beta-adrenergic receptor blockers or flecainide, and if there is no effect from These measures address the issue of catheter ablation. Differential diagnosis and treatment of tachycardia with normal ventricular complexes are presented in the figure below.