PurposeThe physiological flow dynamics within the Valsalva sinuses, in terms of global and local parameters, are still not fully understood. This study attempts to identify the physiological conditions as closely as possible, and to give an explanation of the different and sometime contradictory results in literature.MethodsAn in vitro approach was implemented for testing porcine bio-prosthetic valves operating within different aortic root configurations. All tests were performed on a pulse duplicator, under physiological pressure and flow conditions. The fluid dynamics established in the various cases were analysed by means of 2D Particle Image Velocimetry, and related with the achieved hydrodynamic performance.ResultsEach configuration is associated with substantially different flow dynamics, which significantly affects the valve performance. The configuration most closely replicating healthy native anatomy was characterised by the best hemodynamic performance, and any mismatch in size and position between the valve and the root produced substantial modification of the fluid dynamics downstream of the valve, hindering the hydrodynamic performance of the system. The worst conditions were observed for a configuration characterised by the total absence of the Valsalva sinuses.ConclusionThis study provides an explanation for the different vortical structures described in the literature downstream of bioprosthetic valves, enlightening the experimental complications in valve testing. Most importantly, the results clearly identify the fluid mechanisms promoted by the Valsalva sinuses to enhance the ejection and closing phases, and this study exposes the importance of an optimal integration of the valve and root, to operate as a single system.

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Nearly a century ago Lang (i 885) described the occurrence of retinal detachment in a brother and his sister. Since that time many pedigrees have been presented to illustrate the hereditary nature of some cases of simple (syn. serous, idiopathic, rhegmatogenous, perforated) retinal detachment. Most of the earlier authors related the occurrence of the detachment to the presence and degree of co-existing myopia. Braendstrup (i94I) and Cuendet, Streiff, and Dufour (1958) have described a myopic family of five generations in which dominant transmission of retinal detachment was apparent. The hereditary nature of certain cases of detachment is evident from those pedigrees in which a detachment occurs in non-myopic individuals of a myopic sibship (Millikin, I896; Edmund, I96I). Fransois (I968) has described retinal detachment occurring in an emmetropic family in which dominant transmission occurred. Although this is the usual mode of inheritance in familial cases, recessive and sex-linked (Vogt, I 936) inheritance have also been observed.Vogt (I924) indicated that it is the predisposing retinal or vitreoretinal degeneration rather than the retinal detachment which is transmitted, and in recent years family studies of certain types of retinal degenerative disorders, especially lattice degeneration, have been reported.Recently two brothers with retinal detachments received treatment at the High Holborn branch of Moorfields Eye Hospital, and as their mother and other close relatives were also known to have developed a retinal detachment it was decided to examine as many members of the family as possible in order to detect the presence of any asymptomatic predisposing retinal degenerative lesions which might benefit from prophylactic therapy. MethodsA family tree comprising I IO members was constructed. The progenitors married in I889 and there is good reason for assuming that they were cousins. An attempt was made to contact as many surviving members of the family as possible. Most were aware of the family history of retinal detachment and welcomed the opportunity to be examined; a small number declined the offer or lived too far away to attend. In the latter case, the local ophthalmologist was informed and asked to examine the patients. Children under the age of 5 years were excluded from the survey. 59 patients were examined either at Moorfields Eye Hospital, or at the Eye Department of the Kent and Sussex Hospital, Tunbridge Wells. An ophthalmic and general medical history were obtained. Routine ophthalmic examination included direct and indirect ophthalmoscopy, and the Goldmann 3-mirror gonioscope was used whenever possible.Information regarding a further six patients was obtained by studying case sheets of patients examined and treated elsewhere.

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