Comparison of biomechanical and structural properties between human aortic and pulmonary valve.

OBJECTIVE: Pulmonary valve autografts have been reported as clinically effective for replacement of diseased aortic valve (Ross procedure). Published data about pulmonary valve mechanical and structural suitability as a long-term substitute for aortic valve are limited. The aim of this study was to compare aortic and pulmonary valve properties. METHODS: Experimental studies of biomechanical properties and structure of aortic and pulmonary valves were carried out on pathologically unchanged human heart valves, collected from 11 cadaveric hearts. Biomechanical properties of 84 specimens (all valve elements: cusps, fibrous ring, commissures, sinotubular junction, sinuses) were investigated using uniaxial tensile tests. Ultrastructure was studied using transmission and scanning electron microscopy. RESULTS: Ultimate stress in circumferential direction for pulmonary valve cusps is higher than for aortic valve (2.78+/-1.05 and 1.74+/-0.29 MPa, respectively). Ultimate stress in radial direction for pulmonary and aortic cusps is practically the same (0.29+/-0.06 and 0.32+/-0.04 MPa, respectively). In ultrastructural study, different layout and density in each construction element are determined. The aortic and pulmonary valves have common ultrastructural properties. CONCLUSIONS: Mechanical differences between aortic and pulmonary valve are minimal. Ultrastructural studies show that the aortic and pulmonary valves have similar structural elements and architecture. This investigation suggests that the pulmonary valve can be considered mechanically and structurally suitable for use as an aortic valve replacement.

Experimental microsurgery of salivary ducts in dogs.

The results achieved by experimental microsurgical suturing of salivary ducts in dogs are presented. Nine partial lesions and one complete transection of the ducts were made on parotid and submandibular ducts. Four to seven interrupted microsutures were used for each lesion. The operations were successful in seven out of 10 cases, as observed by sialography. Histologically, granulation tissue compressing the ducts was observed after suturing the lesions. Four venous graft transplantations were performed and none were successful. After venous graft transplantation, the transplant was not apparent histologically, raising doubt as to the potential success of this technique. The use of stenting is discussed based on a summary of the published literature. Those reports indicate that long-term stenting can benefit the outcome of salivary duct repair. The use of dogs as a model for experimental salivary duct operations has been shown to be valuable in assessing various surgical techniques. Copyright 2001 European Association for Cranio-Maxillofacial Surgery.