The so-called preexcitation syndrome refers to a syndrome in which, in addition to the normal conduction system in the heart, there are additional conduction pathways between the atria and the ventricles (e.g., the additional bypasses shown in Fig. 1), which cause electrical impulses from the atria to preexcite some or all of the ventricular muscle. The syndrome was first reported in 1930 by Drs. Wolff, Parkinson, and White and is therefore also known as W-P-W syndrome. The prevalence of preexcitation syndrome ranges from 0.15% to 1.6%, with a male predominance. Ventricular preexcitation itself does not produce symptoms and generally has a good prognosis. Chen Yingwei, Department of Cardiovascular Medicine, First Affiliated Hospital of Zhengzhou University Figure 1: Additional bypass shown by red arrows Pre-excitation alone does not cause symptoms, and those with underlying heart disease may have associated symptoms and signs. However, preexcitation syndromes often result in multiple arrhythmias, with atrioventricular tachycardia being the most common (approximately 80%) (Figure 2 shows a preexcitation bypass-mediated tachycardia episode with a ventricular rate of approximately 200 beats per minute). It should be noted that preexcitation is often combined with atrial fibrillation, and atrial waves can reach 350-600 beats/min during an episode of atrial fibrillation. Such rapid atrial waves can be transmitted down the bypass tract, so that preexcitation syndromes combined with atrial fibrillation or atrial flutter can produce rapid ventricular excitation (most ventricular rates are particularly fast, up to 180-200 beats/min, and when the ventricular rate is greater than 200 beats/min, it can lead to ventricular fibrillation, and the risk of sudden death is significantly increased in the patient. Patients are at a significantly increased risk of sudden death) (as shown in Figure 3 atrial fibrillation episodes with rapid ventricular rate, ventricular fibrillation). Figure 2: Electrocardiogram of a pre-excited patient during an episode of tachycardia, with a ventricular rate of nearly 200 beats/min Figure 3: In pre-excitation combined with atrial fibrillation, rapid atrial fibrillation waves agitate the ventricular myocardium via the collateral channel, causing ventricular fibrillation Diagnosis: The diagnosis of pre-excitation in patients with a typical pre-excitation syndrome electrocardiogram is not difficult. For intermittent pre-excitation syndrome, the diagnosis is often difficult. Multiple electrocardiograms, ambulatory electrocardiograms, and exercise testing can help to detect pre-excitation waves. Treatment: The simple presence of preexcitation waves and the absence of tachycardia episodes, or occasional episodes with mild symptoms, generally do not require treatment. Patients with frequent tachyarrhythmias should be treated with medications, transcatheter radiofrequency ablation, or surgery. Drug therapy: When the preexcitation syndrome is complicated by narrow QRS tachycardia (mostly cis-type refractory tachycardia, in which atrial excitation is transmitted downward to the ventricle through the AV node, and then backward to the atrium through the bypass after refractory return, and the tachycardia is formed in a cyclic manner), atrioventricular node blocking agents such as stimulation of the vagus nerve, intravenous adenosine, and verapamil, etc, may be used for the treatment. When pre-excitation syndrome is complicated by wide QRS tachycardia, adenosine and AV node blockers should be disabled. In this type of rhythm, the ventricle is mostly excited by the anterior conduction of the bypass tract (which can also be manifested as a wide QRS wave when combined with bundle-branch block), and if atrioventricular node blockers are used, conduction can only be transmitted down to the ventricle through the bypass tract, and since the bypass tract does not have the characteristic of the AV node that protects against diminishing conduction, the rapid agitation such as atrial flutter/fibrillation can be Because the collateral channel does not have the protective decremental conduction properties of the AV node, rapid excitations such as atrial flutter/atrial fibrillation can be transmitted to the ventricles in a 1:1 fashion, which may lead to ventricular fibrillation and cardiac arrest. In these patients, drugs that prolong both AV node and paravalvular tract refractory periods (propafenone, amiodarone, etc.) may be considered, and DC cardioversion is preferred in hemodynamically unstable patients. Catheter ablation: Transcatheter radiofrequency ablation is currently the best treatment for preexcitation syndrome (Figure 4), as radiofrequency ablation removes the anatomical basis of the case in which preexcitation syndrome develops arrhythmias and is therefore curative, with a single-procedure success rate of more than 95% in experienced centers. Figure 4: Ablation catheter ablation of pre-excitation bypass shown by red arrow Case: patient 58 years old male, intermittent palpitations for 2 years, reoccurring with black 1 week admitted to the hospital, the patient’s usual electrocardiogram suggests pre-excitation electrocardiogram (left bypass pre-excitation wave, Figure 5), 1 week ago palpitations with black cleaner Mobin technology frightened displays Guilty of atrial fibrillation with bypass pre-excitation, the ventricular rate of nearly 200 beats / min, accompanied by low blood pressure, the outside hospitals to give emergency electrical cardioversion, did not do The patient was admitted to our department, after completing the relevant examinations, cardiac electrophysiology examination confirmed the diagnosis of bypass preexcitation wave located on the left side, and the preexcitation wave was successfully blocked by radiofrequency ablation, and the patient was further catheterized for ablation of atrial fibrillation due to the frequency of atrial fibrillation episodes in general, and the patient was discharged from the hospital with a number of electrocardiograms that were normal, and did not have any palpitations and discomfort. Figure 5: Atrial fibrillation with anterior bypass tract, rapid ventricular rate Summary: Pre-excitation syndrome is a very common arrhythmia, which is generally not harmful, but if pre-excitation is combined with atrial fibrillation, due to the rapid atrial fibrillation wave easily via the anterior bypass tract agitation of the ventricle resulting in ventricular flutter, ventricular fibrillation, which is often life-threatening, and the effect of drug treatment is unclear, and often this case requires catheter ablation surgery, which can avoid excessive atrial agitation through the bypass tract agitation after the success of the blockage of the bypass tract. Successful blockade of the bypass tract prevents excessive atrial excitation from transmitting through the bypass tract to the ventricle, thus preventing sudden death.