CATHETER ABLATION OF LEFT ACCESSORY ATRIOVENTRICULAR CONNECTIONS - THE TRANSSEPTAL APPROACH

Background: In the past few years, there has been a relative explosion of activity in the realm of interventional cardiology. The high rate of success of radiofrequency energy ablation have transformed catheter ablation from an investigational procedure into the first-line therap y for symptomatic Wolff-Parkinson-White syndrome. Radiofrequency cathe ter ablation for preexcitation syndrome is commonly based on a ventric ular approach. Such an approach might be associated with the risk of p rolonged arterial catheter manipulation, retrograde left ventricular c atheterization, and production of multiple, potentially arrhythmogenic , ventricular lesions created during ablation. Potential risks can be avoided using atrial insertion ablation procedures. The transseptal pr ocedure that was developed in the 1950s and 1960s as a diagnostic proc edure and then shelved in the 1970s and early 1980s has now come back into prominence as a therapeutic technique in the treatment of valvula r heart disease, and then in the ablation of the left accessory atriov entricular connections. Methods: Atrial aspect of mitral annulus is a relatively smooth, nonobstructed surface that simplifies catheter move ment, thereby permitting rapid and accurate accessory pathway location . Although primary rise of earliest endocardial retrograde atrial acti vation as a marker of accessory pathway atrial insertion is sufficient ly accurate to permit successful ablation, direct recording of an acce ssory pathway potential is an important predictor of successful ablati on site. Moreover, the analysis of the unipolar atrial electrogram, re corded during sinus rhythm front the tip of the ablation catheter-, pr ovides further information for localizing the atrial insertion of the accessory pathways. Shortest atrial-accessory pathway and negative del ta-accessory pathway intervals have been found to be the best predicto rs of the successful site. Results: A 90.5% success of the transseptal approach on an overall population of 328 patients, higher for overt t han for concealed pathways, is comparable with the results of the retr ograde. Complications are 0.5%. Conclusion: In conclusion. the transse ptal approach for ablation at the atrial site is very safe and highly effective, and avoids prolonged arterial cannulation and catheter mani pulation in the ascending aorta and left ventricle.