Related Experiment Video
Updated: May 3, 2026

Protocol for Relative Hydrodynamic Assessment of Tri-leaflet Polymer Valves
Published on: October 17, 2013
[Turbulence and high intensity transient signals (HITS) as a parameter for optimum orientation of mechanical heart
M Perthel1, J M Hasenkam, H Nygaard
1Herz-Kreislauf-Klinik Bevensen Herz- und Thoraxchirurgie, Römstedter Str. 25, 29549, Bad Bevensen, Germany, M.Perthel@t-online.de.
Background:
In previous studies, the impact of valve orientation on the hemodynamic performance of mechanical aortic valves has been demonstrated. This study investigates Turbulence (RNS values) and High Intensity Transient Signals (HITS) as a new and objective parameter for hemodynamics in various orientations of Medtronic Hall (MH) and St. Jude Medical (SJM) aortic valves.
Methods:
Rotation devices carrying a MH or SJM valve were implanted into four pigs. The device allowed valve rotation without reopening the aorta. In various orientations, turbulent shear stresses (RNS values) and HITS were measured.
Results:
RNS and HITS changed for both valve designs in the different orientations, with superior results for the MH in the hemodynamically best orientation. Downstream turbulence (RNS) and HITS varied in the same direction, but a one to one correlation was not observed.
Conclusions:
RNS and HITS vary with respect to valve orientation and design with superior results for the tilting disc valve. Both MH and SJM valves showed lower turbulence and HITS counts in their hemodynamically best orientations. HITS were related to downstream turbulence and the hemodynamic performance of the mechanical aortic valves.
Related Concept Videos
Heart Valves
The AV valves prevent the backflow of blood from the ventricles to the atria during ventricular contraction. These valves function with the assistance of the chordae tendineae and papillary muscles. When the ventricles are relaxed, the chordae tendineae are slack, allowing blood to flow from the atria into the...
Mitral Regurgitation I: Introduction
Mitral Regurgitation III: Medical Management
Heart Sounds
Auscultation is the process of listening to these internal body sounds using a stethoscope. The heart produces four types of sounds, but only two—S1 and S2—can usually be heard with a stethoscope.
S1, also known as the "lub" sound, is caused by the closure of atrioventricular (A-V)...
Aortic Regurgitation I: Introduction

