Development of an Animal Experimental Model for a Bileaflet Mechanical Heart Valve Prosthesis

Abstract

The objective of this study was to develop a pre-clinical large animal model for the in vivo hemodynamic testing of prosthetic valves in the aortic position without the need for cardiopulmonary bypass. Ten male pigs were used. A composite valved conduit was constructed in the operating room by implanting a prosthetic valve between two separate pieces of vascular conduits, which bypassed the ascending aorta to the descending aorta. Prior to applying a side-biting clamp to the ascending aorta for proximal grafting to the aortic anastomosis, an aorta to femoral artery shunt was placed just proximally to this clamp. The heart rate, cardiac output, Vmax, transvalvular pressure gradient, effective orifice area and incremental dobutamine stress response were assessed. A dose dependant increase with dobutamine was seen in terms of cardiac output, Vmax, and the peak transvalvular pressure gradient both in the native and in the prosthetic valve. However, the increment was much steeper in the prosthetic valve. No significant differences in cardiac output were noted between the native and the prosthetic valves. The described pre-clinical porcine model was found suitable for site-specific in-vivo hemodynamic assessment of aortic valvular prosthesis without cardiopulmonary bypass.

Dual Arterial Cannulation for Aortic Surgical Procedures in Adult Sheep

“…Studies involving an ovine model for prosthetic mitral valve implantation have reported low mortality with acceptable physiological and hemodynamic data [5,6] . However, the use of adult sheep for prosthetic aortic valve implants has produced mixed success due to potential problems such as a limited anatomical length of the ascending aorta in cloven-footed animals [4] . Preoperative echocardiographic assessment can provide an estimated length of the ascending aorta [7] , which is useful information during candidate selection.…”

Computed Tomography-based evaluation of porcine cardiac dimensions to assist in pre-study planning and optimized model selection for pre-clinical research

“…Unlike in the human patient, where the valve is chosen based on the patient's annular size and geometry, in preclinical research a suitable animal is generally selected based on body weight for one particular valve size available for testing. Thus, the suitable animal must be large enough to accommodate human-grade devices, with the determining factors being the size of the target cardiac structure, as well as the diameter of the peripheral vessels used for vascular access 17 .…”