Pathological ECG changes

Pathological ECG changes depending on the nature and impact of a pathological process on the heart and localization and distribution-related disorders of the myocardium (see heart Arrhythmia, myocardial infarction, Heart).
Atrial complex. Changes, and P wave consist in change of its magnitude, direction, duration and form. They can be caused by a lesion of a myocardium of the right or the left atrium, the infringement of sequence during the initiation of muscle fibres separate fibrillation, a violation of the process of excitation in the Atria due to a change in the ratio of electromotive force both fibrillation caused by hypertrophy or extension of the right or the left atrium.
If dextrocardia prong R is negative in all derivations except single pole on the right hand. Atrial fibrillation prong R disappears and all over the ECG appear different magnitude and frequency fluctuations.
At significant damage to attack one of the Atria, and P wave is reduced, often splits, sometimes forks; the duration of its increasing. The segment of the P - TA and The tooth, layering on the interval P-Q and ventricular complex, cause changes of ECG in cases where changes prong R.
Change the interval P-Q are to shift up or down to increase or decrease. The interval offset sometimes observed in the myocardial infarction. The increase in the length of the interval is observed at an increased impact of the parasympathetic nervous system, functional and organic lesions of the conducting system of the heart as a result of infections and intoxications, endocrine disorders, or congenital anomalies.
The reduction of the interval P-Q is observed at an increased impact on the heart of the sympathetic nervous system, changing the point of occurrence of cardiac impulse (with the rhythm of the coronary sinus and atrioventricular rhythm) and electrocardiographic WPW syndrome (see heart Arrhythmia).