What is Preexcitation Syndrome?

Preexcitation syndrome is not actually a disease, because preexcitation is an abnormality of the heart's atrioventricular ventricles, and preexcitation syndrome refers to people who experience the preexcitation phenomenon. If it is a simple pre-excitation phenomenon, there will be no symptoms in the body, only atrial flutter or atrial fibrillation will occur. For preexcitation syndrome, it is necessary to do corresponding examinations so that you can know your physical condition in time.

Preexcitation is an abnormal phenomenon of atrioventricular conduction. The impulse is transmitted through the accessory pathway, prematurely exciting part or all of the ventricles and causing premature excitation of some ventricular muscles. Preexcitation phenomenon is called preexcitation syndrome or WPW syndrome, which is often accompanied by supraventricular paroxysmal tachycardia. Preexcitation is a rare arrhythmia, which is mainly diagnosed by electrocardiogram.

Simple preexcitation is asymptomatic

The concurrent supraventricular tachycardia is similar to general supraventricular tachycardia. In patients with concurrent atrial flutter or atrial fibrillation, the ventricular rate is mostly around 200 beats/min. In addition to discomfort such as palpitations, shock, heart failure and even sudden death may occur. When the ventricular rate is extremely fast, such as 300 beats/min, the heart sounds detected by auscultation may be only half of the ventricular rate on the electrocardiogram, indicating that half of the ventricular excitation cannot produce effective mechanical contraction.

Vectorcardiogram Diagnosis

In addition to the ECG features, the vectorcardiogram can be used as a basis for diagnosis. Its characteristic is that the initial part of the QRS loop on each plane runs slowly in a straight line, lasting up to 0.08 seconds, and then suddenly turns and continues to run at normal speed. The QRS loop operation time can exceed 0.12 seconds. His bundle electrogram and surface or epicardial mapping are helpful in distinguishing various types of preexcitation and locating the accessory pathway, and play an important role in confirming whether the accessory pathway is involved in the tachycardia reentry circuit. The preexcitation pattern on the electrocardiogram should be differentiated from bundle branch block, ventricular hypertrophy or myocardial infarction. The presence of a shortened PR interval and preexcitation waves can confirm preexcitation. When the accelerated ventricular autonomous rhythm and sinus rhythm present interfering atrioventricular dissociation (especially when the ventricular rate is similar to the sinus rate), there may be short bursts of shortened PR interval and wide and deformed QRS complexes on the electrocardiogram, which resemble intermittent preexcitation; but long records can often show irregular PR interval and atrioventricular dissociation, which are not difficult to distinguish from preexcitation. When preexcitation is complicated by supraventricular tachycardia, the QRS complex often does not widen, but after the attack stops, there are characteristic ECG changes except for latent preexcitation. When preexcitation is complicated by atrial fibrillation or atrial flutter, the QRS complex often widens, which should be distinguished from ventricular tachycardia.