Patent Foramen Ovale

While a patent foramen ovale (PFO) is found in ~15% of the normal adult population, it is found in over 50% of young adults with cryptogenic stroke.² The implied mechanism is paradoxical embolization of clot from the right to left atrium and from there to the cerebral circulation. Because of the relatively low risk of recurrent stroke (1% to 5% per year), transcatheter closure of PFOs is currently indicated for patients with cryptogenic stroke and PFO who have had a recurrent stroke on medical therapy.There are two devices that currently have limited FDA approval—the Amplatzer PFO Occluder and the CardioSeal. The limited FDA approval (humanitarian device exemption (HDE)), while not investigational, requires institutional review board oversight and does not permit ‘off-label’ usage. Randomized trials comparing medical therapy with device closure after a first cryptogenic stroke are under way.

PFO closure is also being investigated as a therapy for migraine headaches. Studies have shown a strong association between migraine headache and PFO. The proposed mechanism is paradoxical shunting of vasoactive substances to the cerebral circulation. Recent uncontrolled studies have shown a dramatic reduction in migraine frequency in those patients with PFO who have undergone transcatheter PFO closure.³ Several randomized controlled trials with a variety of transcatheter PFO occluders will start in the US by the end of the year.

Patent Ductus Arteriosus

The ductus arteriosus is a fetal blood vessel connecting the aorta with the pulmonary artery. Normally, this vessel closes in the first days of life; however, if it remains open, this may lead to pulmonary over-circulation, left atrial and ventricular dilation, and pulmonary hypertension. Even in the absence of a significant hemodynamic burden, a patent ductus arteriosus (PDA) is a nidus for endarteritis with a risk of ~1% per year. Indications for PDA closure are therefore any audible or hemodynamically significant PDA.

A variety of devices have been used ‘off-label’ to close PDAs. Small PDAs (≤2mm) are easily closed with stainless-steel Gianturco coils. Larger PDAs are better closed with the Amplatzer Duct Occluder, which is a mushroom-shaped device with a nitinol frame and filled with an occlusive polyester fabric mesh. This device is delivered from the venous approach placing the ‘hat’ in the aortic ampulla and the ‘stem’ in the PDA itself (see Figures 3 and 4). Closure rates are virtually 100% for PDAs up to 10mm and complications are rare.4 Patients who are more than six months old or 6kg in weight are the best candidates for transcatheter PDA closure.

Due to the small delivery system (5–7 French), excellent occlusion characteristics, and low-profile, the Amplatzer PDA Occluder has also been used ‘off-label’ to occlude other congenital and acquired defects. Examples include closure of prosthetic paravalvular leaks, and residual patch-margin ventricular septal defects.⁵