Preexcitation syndrome surgery, understand the condition before surgery

Cardiac preexcitation syndrome is an extra channel in the heart. Generally, if it does not cause tachycardia, no treatment is required. If tachycardia occurs, it will cause palpitations and atrial fibrillation, and timely surgical treatment is required. Common methods include radiofrequency ablation.

1. Treatment methods

Preexcitation itself does not require specific treatment. When concurrent supraventricular tachycardia occurs, the treatment is the same as general supraventricular tachycardia. When atrial fibrillation or atrial flutter occurs, if the ventricular rate is fast and accompanied by circulatory disorders, synchronized direct current cardioversion should be used as soon as possible. Lidocaine, procainamide, propafenone, and amiodarone slow conduction along the accessory pathway, which can slow the ventricular rate or convert atrial fibrillation and flutter to sinus rhythm. Digitalis accelerates conduction along the accessory pathway, while verapamil and propranolol slow down conduction within the atrioventricular node, both of which may significantly increase the ventricular rate or even develop into ventricular fibrillation, so they should not be used. If supraventricular tachycardia, atrial fibrillation or atrial flutter occurs frequently, it is advisable to take the above-mentioned antiarrhythmic drugs orally for a long time to prevent attacks. For patients whose atrial fibrillation cannot be controlled by drugs, whose electrophysiological examination confirms that the refractory period of the bypass is short or the refractory period of the bypass is shortened during rapid atrial pacing, or whose ventricular rate reaches about 200 beats/min during an attack of atrial fibrillation, there are indications for electrical, radiofrequency, laser or cryoablation after positioning, or surgical severance of the bypass to prevent attacks.

2. Disease Diagnosis

Simple preexcitation has no symptoms. The concurrent supraventricular tachycardia is similar to general supraventricular tachycardia. For those 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 auscultatory heart sounds may be only half of the ventricular rate on the electrocardiogram, indicating that half of the ventricular excitation cannot produce effective mechanical contraction. When preexcitation is complicated by supraventricular tachycardia, the QRS complex is often not widened, but after the attack stops, there are characteristic electrocardiogram changes except for latent preexcitation. When preexcitation is complicated by atrial fibrillation or atrial flutter, the QRS complex is often widened, which should be distinguished from ventricular tachycardia.

The preexcitation pattern on the electrocardiogram should be differentiated from bundle branch block, ventricular hypertrophy or myocardial infarction. The presence of 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. However, long records can often show an irregular PR interval and atrioventricular dissociation, which are not difficult to differentiate from preexcitation.

3. Preventive Care

The prevention of preexcitation syndrome is mainly to prevent the recurrence of tachycardia. In order to effectively prevent the recurrence of tachycardia, two drugs should be used to simultaneously inhibit the forward and reverse conduction of the reentrant circuit, such as quinidine and propranolol, or procainamide and verapamil, which can achieve better results. Class IA and IC drugs such as amiodarone or Sol can prolong the irregularity between the atrioventricular accessory pathway and the atrioventricular node, which can effectively prevent the recurrence of tachycardia. Drug selection can be based on clinical experience, or the use of effective drugs determined by electrophysiological examinations can ensure the best effect in preventing recurrence.