Chronic orthotopic aortic valve implantation model.

Area of Science:

• Biomedical Engineering
• Cardiovascular Research
• Surgical Innovation

Background:

• The optimal animal model for assessing prosthetic aortic valves remains undefined.
• Current models often focus on mitral valve implantation due to poor survival rates in aortic valve replacement (AVR) models.
• New regulations necessitate site-specific animal models for preclinical evaluation.

Purpose of the Study:

• To modify and validate a chronic ovine model for orthotopic aortic valve replacement (AVR).
• To establish a predictive animal model for preclinical evaluation of prosthetic aortic valves, assessing safety, hemodynamics, pathology, and handling.
• To provide reliable data for regulatory submissions prior to clinical trials.

Main Methods:

• Fourteen sheep underwent AVR using 19 mm mechanical valves under cardiopulmonary bypass.
• The prosthetic valve was implanted via complete transverse ascending aortic transection.
• Hemodynamic data and aortography were collected intraoperatively and at 20 weeks, followed by pathological examination.

Main Results:

• 11 out of 12 sheep survived the 20-week study period, with two operative deaths.
• Chronic hemodynamic and aortographic data remained within normal limits for surviving sheep.
• Pathological examination revealed no gross abnormalities of the implanted prosthetic aortic valves.

Conclusions:

• The ovine model is feasible for orthotopic AVR, offering confidence in preclinical hemodynamic and angiographic data.
• This ovine model demonstrates improved morbidity/mortality rates, reproducibility, and ease of care compared to other species.
• This surgical technique and ovine model are selected for future prosthetic aortic valve studies.