Bidirectional Block Assessment Techniques During Cavotricuspid Isthmus Ablation: A Comprehensive Review

Ablation of common atrial flutter is one of the most commonly performed procedures in arrhythmia units worldwide. The most frequently used approach involves creating a radiofrequency ablation line between the tricuspid annulus and the inferior vena cava, at the level of the medial cavotricuspid isthmus. The generally accepted endpoint for this procedure is establishment of bidirectional block along this line. Since the late 1990s, various approaches have been used to confirm the presence of this block. However, most of the techniques discussed here have not been compared in large-scale studies. Instead, they are supported by small studies in a limited number of patients, making it difficult to assess the superiority of one technique over another. In addition, long-term follow-up data and recurrence rates are scarce. This comprehensive review presents an overview of the different techniques: we summarise the methodology, appropriate measurement procedures, degree of validity and potential pitfalls encountered in routine clinical practice. The accumulation of favourable results using a combination of different approaches increases the likelihood that the ablation line is electrically impermeable. Thus, we recommend familiarising oneself with all these methods and using multiple techniques to assess cavotricuspid isthmus ablation.