Development and Hemodynamic Analysis of Low-pressure Tubular Heart Valves

Background: Despite numerous approaches to interventional mitral valve replacement therapy, there is no established procedure with similar clinical relevance as the edge-to-edge technique. Therefore, solutions for interventional mitral valve replacement are urgently needed. A promising approach could be the heterotopic implantation of valves in the pulmonary veins. However, these valves must exhibit low resistance in the low-pressure system. In this study, a tubular valve was developed accordingly and compared with a tricuspid valve.

Methods: The tubular heart valves are composed of a flexible, tubular closing body made of bovine pericardium with two end openings. One of these openings is held open by a 3D-printed tubular stent. Two opposing struts are affixed to the second end opening, which is open in the static state, and are directly connected to the stent. Hemodynamic studies were conducted in a pulse duplicator on a tubular heart valve and a three-leaflet Avalus™ bioprosthesis with identical inner orifice diameters of 21.65 mm under varying simulated cardiac output (2.0 L/min, 3.5 L/min, 5.0 L/min, 7.0 L/min) and a mean arterial pressure of 108 mm Hg. The physical examinations were always accompanied by visual documentation of the closing behavior of the valves.

Results: The tubular valve demonstrated a reduction in mean pressure gradients across the valve replacement during the positive differential pressure phase and an increase in effective orifice areas (EOA) in comparison to the Avalus™ prosthesis. For simulated cardiac outputs of 2.0 L/min, 3.5 L/min, 5.0 L/min, and 7.0 L/min and a mean arterial pressure of 108 mm Hg, the mean pressure gradients were reduced to 5.39 ± 0.08 mm Hg, 6.72 ± 0.02 mm Hg, 8.27 ± 0.14 mm Hg, and 10.71 ± 0.10 mm Hg in comparison to the Avalus™, which exhibited mean pressure gradients of 5.63 ± 0.01 mm Hg, 8.25 ± 0.15 mm Hg, 9.77 ± 0.15 mm Hg, and 14.85 ± 0.22 mm Hg. Conversely, the EOA was observed to increase to 1.52 ± 0.02 cm², 2.07 ± 0.01 cm², 2.51 ± 0.03 cm², and 2.93 ± 0.02 cm² in comparison with EOA of the Avalus™, which is found to be 1.45 ± 0.01 cm², 1.88 ± 0.02 cm², 2.32 ± 0.02 cm², and 2.50 ± 0.01 cm².

Conclusion: The results of the comparative analysis between the tubular prosthesis and the three-leaflet bioprosthesis showed lower pressure gradients and increased effective orifice area (EOA) of the tubular valve design. This carries advantages, especially when used in a low-pressure system like the pulmonary veins.

Publication History

Article published online:
11 February 2025