The ECG of preexcitation syndrome is characterized by a shortened PR interval, abnormally wide QRS waves, the presence of preexcitation waves, and secondary ST-T changes.
Pre-excitation syndrome is an abnormality of atrioventricular conduction in which electrical impulses are transmitted downward to excite part or all of the ventricle early, causing premature excitation of the ventricular myocardium.
The electrocardiogram will show a shortened PR interval of less than 0.12 seconds and an acutely broad QRS wave with a QRS wave time limit of more than 0.12 seconds, and secondary changes in the ST-T, which are in the opposite direction of the main QRS wave.
The most typical electrocardiographic change in preexcitation syndrome is the appearance of a coarse, blunt, preexcitation wave at the beginning of the QRS wave cluster that forms a staccato with the rest of the wave.
There are two types of waveforms, type A and type B. Type A preexcitation waves and QRS wave clusters are upward in V1 lead, suggesting myocardial preexcitation of the left ventricle or the posterior base of the right ventricle, and type B preexcitation waves and QRS wave clusters are downward in V1 lead, suggesting myocardial preexcitation of the anterior lateral wall of the right ventricle.
When the ECG shows preexcitation syndrome manifestations, it is necessary to consult a doctor in time to clarify the cause and rational treatment.