Right atrial angiographic evaluation of the posterior isthmus - Relevance for ablation of typical atrial flutter

Background-Gaining anatomic information about the posterior isthmus is not generally part of flutter ablation procedures. We postulated that right atr ial (RA) angiography could rationalize the ablation approach by revealing t he conformation of the isthmus. Methods and Results-In 100 consecutive patients, biplane RA angiography was performed before ablation to guide catheter contact with the isthmus along its length. Angiography showed a wide variation in the width of the isthmu s (17 to 54 mm; 31.3+/-7.9), its angle with the inferior vena cava in the r ight anterior oblique projection (68 degrees to 114 degrees; 90.3+/-9.0 deg rees), and its lateral position relative to the inferior vena cava in the l eft anterior oblique projection, A deep sub-Eustachian recess was revealed in 47%, with a mean depth of 4.3+/-2.1 mm (1.5 to 9.4). A Eustachian valve was visualized in 24%. Ablation resulted in bidirectional conduction block (which could be transient) in all, with a median of 2 dragging radiofrequen cy (RF) applications (2.3+/-2.5 RF applications; 57 degrees C, less than or equal to 99 seconds each). Permanent block was achieved in 99%, with a med ian of 3 RF applications (3.4+/-3.0). The presence of a Eustachian valve or concave isthmus was associated with statistically more RF applications; th e same trend was seen for patients with deep pouches. The number of RF appl ications decreased statistically throughout the study, indicating a learnin g curve. No patient had a recurrence after a follow-up of 13+/-11 months. Conclusions-Right atrial angiography reveals a highly variable isthmus anat omy, often showing particular configurations that can make ablation more la borious. Rational adaptation of the ablation approach to these anatomic fin dings may contribute to successful ablation.