AGA Medical (Plymouth, Minnesota) thus far focused primarily on closing a type of hole in the heart called a patent forman ovale (PFO), a remnant of the fetal foramen ovale. But AGA has received FDA approval of its occlusive device for closing a muscular ventricular septal defect (VSD) and so can now offer this therapeutic alternative to U.S. doctors and their patients. The Amplatzer Muscular Ventricular Septal Defect Occluder, the company says, safely fills the hole and treats VSD, a defect in the ventricular septum, the wall dividing the left and the right ventricles of the heart.

The ventricular septum consists of "an inferior muscular and superior membranous portion and is extensively innervated with conducting cardiomyocytes," according to the company's description of the defect. The device, which is based on work developed by Kurt Amplatz, MD, one of AGA's founders, won the FDA approval after nine years on the European market via the CE mark.

The device is intended to be used in patients for transcatheter closure in specific circumstances - large-volume left-to-right shunt, pulmonary hypertension and/or clinical symptoms of congestive heart failure. The patient must also be considered at high risk for surgical closure, based either on the anatomy of the defect or the patient's overall medical condition.

"Typically this device is geared toward infants - those most affected by VSD and who wouldn't be able to survive heart surgery," John Barr, COO of AGA, told Cardiovascular Device Update. "We've been getting a good response from it in Europe." Plans call for immediate roll-out of the device in the U.S.

The VSD occluder device consists of two discs made of self-expanding nitinol. The device itself is implanted via a catheter, using the percutaneous procedure that contrasts sharply with the alternative of open heart surgery and results in shorter recovery time. It resembles a metal pole with the two discs lining up parallel to one another atop the pole. "The catheter goes into the heart and the physician releases the device using a screw connection," Barr said.

To increase the closing ability, the discs are filled with polyester fabric that is secured to the disc. The Muscular VSD Occluder uses the Amplazter interface between the device and delivery cable. This screw attachment permits the device to be retrieved and repositioned prior to release from the cable.

AGA has agreed to conduct a five-year post approval study to evaluate long-term safety and effectiveness, as a condition for the approval. In addition, AGA said it will enroll at least 100 patients in a prospective registry study to include an evaluation of post-procedural success, occurrence of major complications, as well as longer term success in closing the shunt associated with the VSD.

Other ongoing AGA initiatives include the Amplatzar PFO closure device, which is currently in a Phase III trial launched last October. In that study, the firm proposes a link between a PFO and migraine headache. The company is also engaged in a study examining the ability of PFO closure to prevent stroke.

Barr told CDU that the company is closing in on completion of its stroke trial, but declined to comment on how many patients were involved in both clinical trial studies for "competitive" reasons. However the company previously has said it was expecting up to 400 patients to participate in the migraine clinical trial study.

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