Extravascular protrusion of the Alterra adaptive prestent identified on surveillance computed tomography imaging

The Alterra adaptive prestent is a novel self-expanding device designed to provide a landing zone for the 29 mm SAPIEN 3 valve to treat pulmonary regurgitation in patients with a right ventricular outflow tract that is too large for a balloon expandable valve alone. The mechanism of fixation for the Alterra prestent is radial force from the self-expanding stent frame, combined with a unique set of flared "tines" that protrude from both ends of the stent.

In this report, we describe 6 patients who underwent uncomplicated transcatheter pulmonary valve replacement with an Alterra adaptive prestent and SAPIEN 3 valve and had surveillance chest computed tomography (CT) scans performed 1 day to 21 months after implant. In each patient, the CT scan demonstrated extravascular extension of a portion of the Alterra prestent, without clinical sequelae, but with extension into the ascending aorta in 1 patient and contact with the ascending aorta, left pulmonary vein, or left atrial appendage in 3 others.

Surveillance CT imaging shows that the Alterra prestent can perforate the pulmonary artery and/or right ventricle. Although no sequelae were seen in these patients, prestent perforation has the potential to be clinically important. Implanters should be aware of this finding and its potential implications. As experience with the Alterra prestent grows, it will be important to further define the risk factors, incidence, and implications of this phenomenon.