Biodegradable pericardial implants for bladder augmentation: a 2.5-year study in dogs.

Bladder augmentation using biodegradable pericardial tissue was evaluated in canine bladders. Acetic acid and acetic anhydride treated pericardial tissue grafts were stored in 75% ethanol for 18 to 27 months before implant. Ten dogs weighing 20 to 25 kg. were subjected to a 50% partial cystectomy. After careful separation of the mucosa, bladder muscle and adventitial layers a pericardial graft volumetrically equivalent to the portion of the bladder removed was sutured to the bladder remnant in 2 layers. In 1 control dog the bladder was opened, 50% of the bladder was removed and the bladder was closed primarily. In another control dog the excised bladder was replaced with fresh chemically treated patch material that was never subjected to ethanol storage. Excretory urography and cystography were performed on all dogs. Urodynamics with filling pressures and bladder volumes measured before and after the operation at intervals of up to 36 months confirmed that adequate bladder capacity was achieved. There were no operative complications. Postmortem histological evaluations revealed a smooth epithelialized inner surface with no traces of any surface irregularities or suture lines. The bladder apex showed an intact epithelium and the absence of a smooth muscle layer. The biodegradable acetylated tissue provides an intact structural reservoir for urine and serves as a template for epithelial regeneration. This permits volumetric bladder enlargement while the graft is progressively reabsorbed with time.