BACKGROUND: Regions of turbulence downstream of bioprosthetic heart valves may cause damage to blood components, vessel walls, and also to aortic valve leaflets. Stentless aortic heart valves are known to possess several hemodynamic benefits such as a larger effective orifice area and a lower aortic transvalvular pressure difference compared to their stented counterparts. To date, turbulence analysis downstream of a stentless valve prosthesis has been investigated exclusively indirectly, using magnetic resonance imaging or in animal settings only. The study aim was to investigate turbulence using direct Doppler ultrasonography measurements in subcoronary stentless and stented valves in human subjects.

METHODS: Either stented pericardial valve prostheses (Mitroflow) or stentless valve prostheses (Solo) were implanted in 15 patients in a randomized fashion. Following surgery, blood velocity was measured in the cross-sectional area downstream of the valves using 10 MHz ultrasonic probes connected to dedicated pulsed Doppler equipment. As a measure of turbulence, Reynolds normal stress (RNS) values were calculated, as well as two-dimensional maps of the turbulence distribution. Preoperative and perioperative data were collected prospectively, and postoperative data retrospectively, from hospital records.

RESULTS: The median follow up was 1,624 days. No differences were found in perioperative or postoperative clinical data. Implantation of the Mitroflow valve was significantly faster than that of the Solo valve (p <0.05). Neither was any difference found in the mean or max RNS between the two valve groups. However, the turbulence profiles showed a large variation in the Solo valve compared to the more uniform profiles of the Mitroflow valve.

CONCLUSIONS: Comparable turbulent flow values were found between the two valve types, although the Solo group exhibited a large variation in turbulence profiles. As no clear clinical advantages were shown to exist for stentless valves, a normal stented valve should be the first choice in most cases.