Introduction: One of the mechanisms of atrial tachycardia (AT) after initial pulmonary vein (PV) isolation is PV-gaps related left atrial (LA) flutter. Tetra loop PV related atrial flutter had not been previously described. We report the case of tetra loop PV related LA flutter with inconsistent activation of coronary sinus (CS).
Methods: Patient was reffered to catheter ablation of AT occured after initial PV isolation. CS showed inconsistent activation with variable cycle lenght (CL), where as other sites of LA had regular CL = 210 ms. Reconnections in all PVs was revealed and left PV antra was used as the electrical refferent. Activation mapping show tetra loop flutter confirmed by entrainment. Two loops were related to the double gap at the left PVs, enother two - to the double gap at the right PVs. Fronts collision at the site of mid CS was the cause of its inconsistent activation. Sequential PV reisolation led to organisation of CS activity, followed by AT termination.
Conclusions: Tetra loop PV related macroreentry is unusual mechanism of AT and requires PV reisolation only