Ventricular extrasystole
The clinical significance of ventricular premature beats depends on how often extrasystoles appear and whether they are single, paired or group. Under the group understand several extrasystoles, following each other. Next, you should also consider the configuration of extrasystoles. If extrasystoles have the same configuration, then they come from the same focus and are called monomorphic or monotopic, if extrasystoles are different in configuration, then we are talking about polymorphic or polytopic extrasystole.
In ventricular premature beats, unlike atrial beats, there is always a compensatory pause. This means that the total duration of 2 contractions (before and after extrasystoles) is equal to twice the RR interval of normal contractions. Under the interval RR understand, as mentioned earlier in the chapter on atrial extrasystoles, the distance from one R wave to the adjacent R wave.
The compensatory pause is explained as follows: the excitability of the sinus node and the atria during ventricular extrasystole is not disturbed. Since the excitation from the sinus node reaches the ventricles in the absolute refractory period associated with the extrasystole, the excitation of the ventricles is impossible. Only with the arrival of the next excitation wave from the sinus node is a normal contraction of the ventricles possible.
In ventricular arrhythmia, due to the pathological propagation of the excitation wave, a secondary violation of repolarization also appears in the form of ST segment depression and a negative T wave.
For the treatment of ventricular premature beats, a doctor has various antiarrhythmic drugs, such as beta-adrenergic receptor blockers and propafenone (prescribed only for severe clinical symptoms). Due to the arrhythmogenic effect inherent in all antiarrhythmic drugs (the frequency of heart rhythm disturbances caused by them is on average 10%), the attitude towards them is currently more restrained and they are prescribed with greater caution.
Features ECG with ventricular extrasystoles:
• Premature appearance of the QRS complex
• The broadening of the QRS complex, the configuration of which resembles the blockade of the corresponding PG leg
• Presence of compensatory pause
• Sometimes found in healthy people, but more often in people with heart disease.
• Treatment is indicated only when clinical symptoms appear. Assign beta-adrenergic receptor blockers, propafenone, amiodarone