Kõrvalahelad

Kõrvalahelad refers to accessory pathways that can conduct electrical impulses in the heart, bypassing the normal route through the atrioventricular (AV) node. These pathways are embryonic remnants that may persist into adulthood. They are often associated with supraventricular tachycardias (SVTs), particularly Wolff-Parkinson-White (WPW) syndrome. In WPW, the accessory pathway allows for rapid electrical conduction from the atria to the ventricles, leading to pre-excitation of the ventricular muscle. This can manifest as a characteristic delta wave on an electrocardiogram (ECG).

The presence of an accessory pathway itself does not necessarily cause symptoms. However, when these pathways participate in re-entrant circuits, they can trigger episodes of rapid heart rate. The most common re-entrant circuit involves the accessory pathway and the normal AV nodal conduction system. During a tachycardia episode, the electrical impulse travels down one pathway and up the other, creating a loop. This can result in a very fast heart rate, sometimes exceeding 200 beats per minute, which may cause palpitations, dizziness, shortness of breath, or even syncope.

Diagnosis of an accessory pathway is typically made through an ECG, which may show signs of pre-excitation. Electrophysiology studies (EPS) are often performed to confirm the presence and location of the pathway and to assess its properties, such as its ability to conduct impulses in both directions and its refractory period. Management strategies for symptomatic accessory pathways range from medication to interrupt or prevent tachycardias to catheter ablation, a procedure that aims to eliminate the accessory pathway using radiofrequency energy or cryotherapy. Catheter ablation is highly effective and is often considered the treatment of choice for patients experiencing symptomatic arrhythmias related to accessory pathways.