Iatrogenic biatrial flutter. The role of the Bachmann’s bundle
Emilio Constán, Francisco García, Antonio Linde. Complejo Hospitalario de Jaén, Jaén. Spain
A 63-year-old male patient with a history of atrial fibrillation and common flutter ablated successfully in 2012. Perimitral flutter episode in 2019, performing an anterior mitral line without cessation of the flutter, requiring electrical cardioversion. In 2023 an atypical flutter recurs (Figure 1).
With suspicion of perimitral atrial flutter recurrence, a decapolar catheter is introduced into the coronary sinus, showing exact return cycles at the level of distal dipoles and +24 ms in proximal dipoles. (Figure 2)
Electroanatomical reconstruction of the left atrium was performed with a multipolar catheter, showing isolation of the 4 pulmonary veins and persistence of the anterior mitral line block. Likewise, the activation map of the left atrium revealed the presence of a macroreentrant tachycardia, although without complete cycle integrity around this cavity, for which an electroanatomical map of the right atrium was performed (Figure 3).
Once the activation map of both atria was made, it was possible to appreciate the propagation of the wavefront around the mitral annulus in a clockwise direction, penetrating towards the epicardium through the coronary sinus and ascending through the interatrial septum until the insertion of the superior vena cava, to return again towards the anterior left atrial wall, finally descending through the mitral annulus (Video 1).
With the final diagnosis of biatrial flutter with involvement of the Bachmann bundle, radiofrequency applications were made at the anteroseptal level of the left atrium, producing suppression of the tachycardia in the first seconds, remaining non-inducible after the waiting time and reinduction attempts using atrial pacing (Figure 5 and Video 2). No recurrence was observed during follow-up.
Although the recurrence of perimitral flutter is greater by performing a lateral mitral line due to the myocardial thickness at this level, the anterior mitral line is the only factor for the appearance of iatrogenic biatrial flutter1. The existence of epicardial connections between the left atrium and the coronary sinus, as well as between the right and left atrium through the Bachmann’s region delimit the biatrial circuit, bypassing the anterior mitral line block (Figures 4-6- Bachmann’s Bundle). Ablation at the level of the interatrial septum allows the termination of flutter2
- Mikhaylov E, et al. Biatrial tachycardia following linear anterior wall ablation for the perimitral reentry: incidence and electrophysiological evaluations. J Cardiovasc Electrophysiol, 26 (2015), pp. 28-35
- Nayak HM, Aziz ZA, Kwasnik A, et al. Indirect and Direct Evidence for 3-D Activation During Left Atrial Flutter: Anatomy of Epicardial Bridging. JACC Clin Electrophysiol 6 (2020): 1812-182