Figure 1. Representative transoesophageal echocardiographic images of different mechanisms of ineffective PFO closure.

A. Incomplete stitch detachment: one of the most frequently identified mechanisms of ineffective PFO closure was partial stitch detachment with opening of the foramen ovale and right-to-left passage of microbubbles at bubble test. In this case the stitch is placed only on the septum secundum; B. Incomplete stitch detachment: the same mechanism described in (A) but in this case the NobleStitch was found on the septum primum resulting in recurrent atrial shunt; C. Atrial septal tear: a new atrial septal tear occurred very close to the stitch after the NobleStitch procedure causing a left-to-right shunt; D. KwiKnot embolisation: complete detachment of the stitch and the KwiKnot into the pulmonary circulation resulting in PFO reopening. PFO: patent foramen ovale; RLS: right-to-left shunt; TOE: transoesophageal echocardiography