Closure of patent foramen ovale: technique, pitfalls, complications, and follow up.

T he first atrial septal defects (ASDs) were closed percutaneously in 1974 and reports about their closure published in 1976. In the 1980s the Rashkind occluder was introduced and revived the interest in the topic, focusing for the first time on the patent foramen ovale (PFO). This device is still available in two modified versions. Its initial name, Rashkind Clamshell occluder, has been changed, first into CardioSEAL and more recently into STARFlex (Nitinol Medical Technologies, Boston, Massachusetts, USA). Two other devices are the Sideris Buttoned Device (Custom Medical Devices, Amarillo, Texas, USA) and the Angel Wings device (Microvena Corp, Whitebear Lake, Minnesota, USA), more recently called the Guardian Angel device. The ASDOS device and the Monodisk device are no longer on the market. All these devices had one major problem in common pertaining to the closure of ASDs. They were not selfcentering. Although some efforts were made to remedy this with intricate nitinol wire constructions or interlinking filaments, the only self-centering device was introduced in the 1990s—the Amplatzer ASD occluder. Figure 1 shows a selection of these devices. The PFO was initially considered by interventional cardiologists simply as one of the manifestations of an ASD to be left to their paediatric colleagues. However, about 10 years ago, it was realised that the PFO not only represented the most common form of an ASD but that it also exhibited its problems exclusively in adults and represented the easiest target for closure. A derivative of the Clamshell occluder was dedicated to PFO closure and named PFO STAR (Cardia, Burnsville, Minnesota, USA); the Amplatzer occluder was modified for the PFO indication and first implanted on 10 September 1997 by the author in the presence of Kurt Amplatz, the inventor. Like all Amplatzer occluder devices, it consists of a nitinol mesh double disk containing polyester fabric inside the two disks. The disks are connected by a thin neck formed by the woven wires forming the disks. The neck is twisted around its long axis and hence is extendable. The device has to be screwed on to a pusher/puller cable and pulled into an 8 or 9 French introducer sheath. When pushed out of the sheath, it resumes its disk shape instantly. The whole process is fully reversible, as many times as required, up to the moment the device is unscrewed from the pusher/ puller cable. Three sizes of Amplatzer PFO closure devices are available and named after the diameter of the right sided disk. The most commonly used 25 mm Amplatzer PFO occluder features a right sided disk of 25 mm diameter and a left sided disk of 18 mm diameter. The 18 mm PFO occluder comprises two 18 mm disks and is meant for small PFOs with a stable septum primum. The 35 mm Amplatzer PFO occluder is destined for large PFOs with an extremely redundant and flimsy septum primum (atrial septum aneurysm) and features a 35 mm disk on the right side and a 28 mm disk on the left side. It requires a 9 French sheath in contrast to the two smaller devices fitting through an 8 French sheath. The PFO STAR device is made by square Ivalon patches fixed to two nitinol cross bars connected by a 2 mm metallic axis. The pusher cable is derived from a biotome gripping a ball tip at the right side end of the axis. The two squares are attached in a way that the blunted nitinol wire tips alternate to avoid pressure necrosis of the tissue between two opposed wire ends. The device comes in several sizes. The minimum sheath size is 10 French, the maximum 12 French. More recent generations of these devices feature a hexagon shape. The Helex septal occluder is the most recently developed of the devices (WL Gore and Associates, Flagstaff, Arizona, USA). It is a hybrid device recommended for PFO and ASD closure. It has a distensible neck in its final shape but also some self-centering qualities. It consists of a nitinol wire with a polytetrafluoroethylene patch attached in a banner-like fashion. Within the delivery sheath it is fully elongated. Once implanted, it forms a double disk (15–35 mm in diameter), one on each side of the septum. The sheath size required for implantation is 9 French. The most widely used devices so far for PFO closure are the CardioSEAL device in the USA (2000 to 2002 the only one available) and the Amplatzer PFO occluder in the rest of the world (available in the USA since 2002). The CardioSEAL device was the model for the PFO STAR and differs from it in two major aspects. The wires spreading the tissue have joints made of spring coils shaped into the wires, and the release mechanism employs the principle of a ball tip end on the device and a ball tip end on a cable within the pusher. Inserting the ball tip end of the device first into a cylindrical case at the end of the pusher and pulling back the ball tip end of the pusher cable, the ball tip of the device is enclosed in the case until the pusher cable is pushed out of the case first, thereby releasing the ball tip end of the device. The introducer sheaths required for the different sizes of the CardioSEAL or STARFlex devices vary from 10 to 14 French.