What does ventricular preexcitation mean?

The heart is a relatively complex organ, and its function is unique in the body. Heart disease is also a series of diseases with a high incidence in life. It can cause serious harm to the patient's body and directly threaten the patient's life and health. For example, ventricular preexcitation is a heart disease with very serious consequences. Let's take a look at what ventricular preexcitation means?

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. People with pre-excitation phenomenon are called pre-excitation syndrome or WPW (Wolf-Parkinson-White) syndrome, which is often accompanied by supraventricular paroxysmal tachycardia. Preexcitation is a rare arrhythmia, which is mainly diagnosed by electrocardiogram.

Symptoms: Simple preexcitation is asymptomatic. Concurrent supraventricular tachycardia is similar to general supraventricular tachycardia. For patients with 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.

The cause of the disease is the presence of a congenital atrioventricular accessory channel (also known as an accessory pathway) outside the normal atrioventricular conduction system. Most patients have no organic heart disease. It is also seen in certain congenital and acquired heart diseases, such as tricuspid valve dysplasia, obstructive cardiomyopathy, etc. Electrophysiological studies have shown that the conduction speed of the bypass is fast, and part of the atrial impulse is quickly transmitted down through the bypass, reaching the ventricular end of the bypass in advance, exciting the adjacent myocardium, thereby causing premature ventricular excitation and changing the normal excitation order of the ventricular muscle. As a result, the QRS complex on the electrocardiogram is deformed, with a pre-excitation wave (δ wave) in the initial part. The remainder of the atrial impulse can be transmitted along the normal pathway and merge with the ventricular excitation caused by the bypass pathway to form a ventricular fusion wave. The morphology of the ventricular fusion wave is determined by the length of the refractory period of the normal and accessory pathways. If the refractory period of the normal pathway is long, or most of the impulses are conducted along the bypass pathway, the QRS deformity will be obvious; if the refractory period of the bypass pathway is long, the ventricular fusion wave will be close to normal.

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