Signs of atrial arrhythmia on ECG
• Typically early appearance of a slightly deformed R-wave. There is no compensatory pause.
• The frequency of atrial beats in IHD is increased. Relatively often, atrial extrasystoles appear in vegetative-vascular dystonia.
Normally, people with a healthy heart have sinus rhythms. This means that normal physiological arousal occurs automatically in the sinus node and the heart contracts in time with the pulses generated in the sinus node. This phenomenon is called the automaton heart.
At a sinus rhythm normal teeth P and the QRS complexes are registered through identical intervals of time.
Heart rate is normal, as already mentioned, is about 60-80 beats per minute. In sinus bradycardia, the heart contracts with a frequency of less than 60 beats per minute, and in sinus tachycardia, the heart contracts with a frequency of more than 100 beats per minute.
Atrial premature beats are characterized by the premature appearance of individual atrial contractions. Since atrial extrasystoles appear as a result of pathological excitation in some part of the atrium wall, the P wave, which reflects the onset of pathological atrial excitation, is deformed and has not a semilunar shape inherent in it, but a pointed or bizarre and is located above the isoline (positive) ; sometimes the P wave is biphasic.
The remaining intervals and the teeth on the ECG are normal, in particular the atrial extrasystoles, do not affect QRS complexes, since the conduction of arousal from the atria to the ventricles is not disturbed. Only with very early atrial extrasystoles, some deformation of the QRS complexes is possible due to aberrant excitation in the ventricular myocardium.
Another feature of atrial premature beats is that the total duration of the RR interval before and after the extrasystoles is less than twice the RR interval. The RR interval is the time interval between two teeth of R. In atrial extrasystoles, unlike ventricular, there is no compensatory pause. This is due to the fact that the excitation of the sinus node is suppressed in the retrograde direction by the atrial extrasystole and premature atrial excitation occurs.
With very early extrasystoles, the AV node may be still in the period of absolute refractoriness, and the conduction of arousal into the ventricles is blocked. In this case, the P wave is recorded, which, however, is not followed by the ventricular QRS complex (blocked atrial extrasystoles). This is a special form of atrial arrhythmia.
Frequent atrial premature beats, especially with polymorphic P wave, often turns into atrial fibrillation.
Single atrial extrasystoles can also be recorded in people with a healthy heart, especially in vegetative dystonia, while frequent atrial extrasystoles are a sign of pathology (for example, IHD, cardiomyopathy, heart defects).
ECG features in atrial arrhythmia:
• Premature appearance of the P wave on the ECG
• Easy deformation of the P wave
• Lack of compensatory pause
• Background heart disease: vascular dystonia and ischemic heart disease
• Therapy: beta-adrenergic receptor blockers, verapamil, quinidine