Right ventricular outflow tract reconstructive model in adult sheep.

Patients born with congenital right ventricular outflow tract lesions are faced with invasive procedures to establish hemodynamic and physiological stability. Commonly, multiple subsequent surgical procedures are required due to deterioration of a previous repair. These procedures carry additive risks of mortality and morbidity. Less aggressive procedures with accompanying lower risk is ideal. Success in percutaneously placing a transcatheter valve has previously been reported; however, continued safety and efficacy of any technique needs continual assessment. We developed a model for preclinical evaluation of a percutaneous placement of a pulmonic transcatheter valve in adult sheep, including preoperative, surgical, and postoperative techniques for long-term evaluation. Adult sheep were assessed and determined to be acceptable for study enrollment. Perioperative antibiotics and analgesics were given prior to a left thoracotomy. A Medtronic, Hancock 1 valve conduit was inserted for reconstruction of the right ventricular outflow tract. The Hancock 1 valve conduit alone represented the control group and the test animals comprised the addition of a Melodytrade mark transcatheter pulmonary valve (TPV), within the Hancock 1 valve conduit. Fifteen adult sheep survived the surgical implant procedure with no perioperative mortality. There were four early postoperative deaths, three due to infection and one due to heart failure, secondary to intraoperative heart block. The remaining 11 animals remained healthy, gained weight, and survived to termination at 5 months. An initial definite-sized valve conduit was implanted, followed by inserting a single size TPV, which allowed a more accurate physiological assessment of any chosen valve. Our developed adult sheep model for percutaneous TPV implantation for right ventricular outflow tract lesions was successful for long-term assessment by utilizing our preoperative, surgical, and postoperative techniques.

Orthotopic total aortic root replacement model in adult sheep.

Prosthetic heart valves undergo mandatory preclinical animal testing prior to human clinical trials. Historically, a non-site-specific placement of a valve prosthesis has been commonly performed; however, recently site-specific placement continues to attract interest. Various animal models have been used for preclinical evaluation of both aortic and mitral valve prostheses; however, a universally accepted animal model for orthotopic total aortic root replacement with acceptable early and late mortality for long-term evaluation has been lacking. This article reports a successful orthotopic model for placement of tissue valve conduit prosthesis for total aortic root replacement in adult sheep. This model utilized preoperative echocardiographic assessment, specific intraoperative surgical techniques, and both early and late postoperative management therapies. The combination of all of these components resulted in a successful model for orthotopic placement of a tissue valve prosthesis for total aortic root replacement in adult sheep for potential long-term assessment.