.webp)
Pre-excitation is a cardiac medical condition that refers to premature ventricular contraction induction. It usually develops as a result of the presence of bypass pathways along with normal conduction pathways from the sinoatrial node through the atrioventricular node down to the hid bundle and Purkinje fibers. These accessory pathways can be found in the atriofascicular, fasciculoventricular, nodofascicular, and nodoventricular areas. In this case, electrical impulses can be transmitted through normal pathways, bypass pathways, or both. It is associated with tachyarrhythmia and is reflected in many changes upon electrocardiography.
Wolf Parkinson White syndrome is a congenital arrhythmic condition, classified as an autosomal dominant trait, where insulted tissues in the atrioventricular junction are not maturated and accessory pathways are formed. As a result, abnormal impulses can be conducted in anterograde or retrograde directions through the accessory pathway. It is usually not associated with other structural heart disorders, but it participates in paroxysmal supraventricular tachycardia (SVT) and is associated with fatal ventricular arrhythmias.
The most common bypass tract associated with Wolf Parkinson White syndrome is an atrioventricular accessory pathway, which is also known as the Kent bundle. They are usually located at the left or right lateral, right anteroseptal, or posteroseptal. These accessory pathways have different electrical properties compared to normal conduction pathways and can form a reentry electrical circuit, which is associated with arrhythmia development.
Premature atrial impulses can activate the normal physiological electrical pathway into the ventricle, which later, through the normal pathway, can activate the accessory pathway and result in retrograde electrical conduction through it back into the atrium to form a reentry circulation. This condition is called orthodromic tachycardia. However, orthodromic tachycardia can also be involved with other tachycardia conditions other than Wolf-Parkinson-White syndrome.
In rare cases, ectopic atrial impulses can activate accessory pathways rather than normal conduction pathways. So, the signal is conducted in the anterograde direction in the accessory pathway. After that, the accessory pathway can result in the activation of the normal pathway and reentry circulation formation. This condition is called antidromic tachycardia.
The inherited factor is observed through mutations in glycogen storage, such as in Pompe and Danon diseases. Which may cause disturbances in the conduction system and participate in WPWS, along with other cardiomyopathy features. Furthermore, the Ebstein anomaly is associated with WPWS through accessory pathway formation at the right ventricle posterolateral wall.
Accessory pathways act as an extra anterograde tract for atrial impulses in atrial flutter and 10–30% of atrial fibrillation cases, despite the fact that the origin of arrhythmia in these conditions is independent of these pathways. As a result, if the heart impulse rate is markedly elevated, it may result in 1:1 fetal ventricular fibrillation through accessory pathways. Moreover, WPWS is usually not associated with ventricular tachycardia, as it is not accompanied by structural heart diseases.
Patients with the Wolf Parkinson's White pattern have electrical changes compatible with the diagnosis, but they may not be associated with any overt symptoms. But if the patient complains of palpitations, chest pain, dizziness, and syncope along with electrical changes, then it is called Wolf-Parkinson-White syndrome.
The electrocardiograph (ECG) is able to detect some changes that are sufficient for a Wolf-Powell diagnosis, which include:
References
.webp)
.webp)
.webp)
.webp)
.webp)
.webp)