Supraventricular tachycardia (SVT) including atrioventricular reentry tachycardia (AVRT) and atrioventricular nodal reentry tachycardia (AVNRT) were most common arrhythmia in pediatric population. Long term treatment in SVT includes medical control and ablation therapy. Choice of the management tools depend on the patient age and possible complication. Catheter ablation for SVT has high successful rate and low recurrence rate. Nevertheless, many new tools have been developed to increase safety and efficacy of ablation recently. Non-fluoroscopic mapping technique has been developed for years. Now, zero-fluoroscope mapping and ablation can be achieved in more than 90% of patients with similar successful rate and recurrence rate. Cryoablation is another new tool. The cryoablation can totally eliminate risk of atrioventricular block, which is one of the most serious complication for perinodal arrhythmia ablation.
　　Supraventricular tachycardia can sometimes associate with CHD like Ebstein's anomaly patients. Transcatheter ablation has high success rate but recurrence is not uncommon. For the postoperative atrial arrhythmia in rCHD, atrial flutter (AF) and IART are the most common but also most difficult to treat. The presence of the atrial arrhythmia may increase morbidity and mortality in these patients, therefore aggressive treatment is necessary. Medical treatment seldom succeeds. Surgical revision with concomitant cryoablation can be performed in selected patients as Fontan operation patients. The transcatheter ablation is still the mainstay treatment, and introduction of 3D mapping greatly increase the success rate and should be used in these complex anatomy patients.
　　With the advance of surgical technique and perioperative care, most of the congenital heart disease patients can survive into adulthood, and the long term complication including tachyarrhythmia and bradyarrhythmia became an important issue in these repaired congenital heart disease (rCHD) patients.
　　The late arrhythmia is more and more common with the increasing age both in simple CHD and in more complex CHD with complex surgery.
　　The late arrhythmia we faced include tachyarrhythmia as supraventricular tachycardia and VT and also bradyarrhtha as AV block and SSS.
We will talk about VT first.
　　This 25 y/o repaired TOF pts complained about frequent fainting out in recent months. The EKG at ED during one episode showed wide QRS tachycardia and LBBB pattern. After DC cardioversion, it then returned to sinus rhythm. We can see the baseline EKG still showed wide QRS, RBBB pattern and prolonged QRS duration.
　　TOF is the prototype of VT in rCHD pts. Although total correction can be achieved by VSD repair and RVOT reconsturction, residual hemodynamic problem including pulmonary regurgitation and ensuing RV dilatation can cause later problem.
　　Previous studies showed late death is common in these patients, and increase with age. SCD accounts for near 1/3 of the patients either in Western country or in our study.
　　Dr. Gatzoulis has proposed mechanoelectrical interaction as the possible mechanism of VT and SCD in these patients.
　　So PVR has been studied for since 2005 and early report suggested it can decrease VT rate.
　　However, recent large scale study didn't support this finding. VT frequency is still the not decreased in these patients.
　　Some suggest the simple reentry mechanism as the possible cause of VT. They proposed VT isthmus ablation to cure the VT. However, several recent large scale study suggest either transcatheter mapping and ablation or intraoperative cryoablation may decrease, but can't totally eliminate the VT substrate.
　　So there should be other explanation for the VT.
　　We performed serial study about the mechanism. Using human study and animal model, we found repolarization heterogeneity may be important in the pathogenesis of VT, which can also link the mechanical and electrical factors.
　　Therefore we suggested the repolarization heterogeneity may be the central pivot which cause low repolarization reserve, high risk of VT and SCD. Both mechanical factors and genetic factors may increase repolarization heterogeneity. So PVR which can decrease mechanical factors, and drug used, which may increase repolarization reserve may have some benefit in these patients but can't totally eliminate the risk. So ICD is still necessary in these patients.
Then let's take about SVT.
　　SV arrhythmia in the CHD include PSVT as AVRT, AVNRT and atrial arrhythmia including AT/AF/IART/Af. These may relate to atrial dilatation due to hemodynamic factors or surgical scar related.
　　Drug therapy is often the first line therapy, and especially important in small children. However, life long therapy is often necessary. Long term side effect is a problem. Catheter ablation….
In boston children hospital, they present their result of ablation for SVT in these CHD patients. The success rate is around 80% but the recurrence rate is not low.
　　We also report our ablation result of PSVT including TAVNRT, AVRT, and AVNRT in single ventricle physiology patients. The success rate is 85%, and recurrence rate is 16%.
The more difficult part is atrial arrhythmia. Because of variant CHD anatomy and surgical procedure, the atrial arrhythmia substrate can be very complex.
　　These patients are often less tolerable to arrhythmia because of hemodynamic problem. Again, medical therapy is still the first line therapy. Amiodarone and sotalol were reported to have 50% success rate but the recurrence rate is high. Besides the long term side effect is a problem. catheter ablation is still the mainstay treatment in nowadays.
Using the 3D mapping system, the success rate can be as high as 80%, but recurrence is still a problem. The recurrence rate is especially high in Fontan patients.
The potential difficulty in ablation of AA in rCHD pts includes….
Therefore, compared to acquired heart disease, the result of ablation in AA is always poorer in CHD patients.
Then we see the patients.
　　The result from Netherland also showed similar finding. After successful ablation, the recurrence rate can be as high as 30%in 5 years FU. And most of the 2nd arrhythmia is AT but not AF. Although with high recurrence, the arrhythmia score is lower for those after successful ablation both with and without recurrence. This means the recurrence frequency is lower and less drug is necessary.
　　The ablation result for Fontan operation is poorer. In this situation, Fontan conversion to TCPC with intraoperative maze is indicated to decrease arrhythmia recurrence.
　　For bradyarrhythmia, this is a pt after senning operation for TGA. He complained about frequent near syncope, and baseline EKG showed heart rate only 34bpm. The Holter showed long pause for 7 seconds. The SSS often related to extensive atrial surgery as atrial switch or Fontan operation. Some may be due to underlying heart disease as LAI and l-TGA.
　　We can see here the extensive atrial surgery, which can damage sinus node, the sinus nodal artery and cause SSS. The SSS rate increase gradually during FU, and more than half of the patients developed SSS by the age of 20.
　　Because AV synchrony is necessary for the borderline hemodynamics in these pts, AAI or DDD is often implanted. For Fontan pts, epicardial lead is often necessary, but for Senning pts, endocardial lead is feasible.
So in the pt we just mentioned, we put an AAI PM in the left side pulmonary atrium.
　　For postoperative AV block, as it carries high mortality rate without treatment, pacemaker is often necessary.
　　In previous studies, if AV block developed after operation, some of the AV block may recovered, but most of them within 7 days. So in the current guideline, pacemaker should be implanted if AV block persisted at least 7 days.