The Outlet Orifice Diameter of Surgical Bioprosthetic Aortic Stented Valves Is Predominantly Much Smaller Than the Inlet Orifice Diameter.

Objectives: Surgical prosthetic valve labelling is misleading, as labelled diameters (LDs) are currently always larger than inlet orifice diameter (IOD), while the outlet orifice diameter (OOD) is unknown. The IOD, OOD, and height of the flow channel determine its conical shape. The instructions for use (IFUs) do not list all essential metrics. This study reports a comprehensive overview of all relevant aortic stented tissue prosthetic valve metrics.

Methods: We measured the OOD of these valves with an optical method. Height was measured using a calliper. The conicity angle of the flow channel was calculated. We hunted for IFU on the internet and in packaging boxes.

Results: Eight valve models of 4 manufacturers were included. In all but 2 models, the OODs were smaller (89%, range 83%-95%) than their IODs, which depicts a converging shape of the flow channel. In 1 model (Avalus) OOD equals IOD, implicating a cylindrical flow channel; and 1 model (Crown) has a diverging shape. The proportion of OOD in relation to IOD seemed to be consistent among the different sizes within the same model type.

Conclusions: Information on metrics for surgical aortic tissue valves is incomplete, scarce, and confusing. This article shows a comprehensive overview of valve metrics, which makes it possible to compare different aortic valve models and sizes. Flow channel shape turned out to be different amongst models. The smallest flow channel diameter is most often the OOD. Since LD should reflect the IOD, one must be aware of all relevant metrics.