Heart Valves

Numerous designs of heart valve prostheses have been in use for more than half a century. In addition to several other factors (e.g. manufacturability, price, interventional complexity, performance etc.) the longevity of the prostheses is an important design goal, especially in an ageing society where patients shall be albe to continue their active lifestyle without the need for re-operation.

A thorough understanding of the hemodynamics of heart valves is indispensable for the design of more durable and better performing devices. To this end, we have developed sophisticated experimental and computational infrastructure for the study of heart valve hemodynamics. This includes pulsatile flow loops, silicone casting facilities, as well as modern optical measurement technology for quantifying the complex three-dimensional blood flow interacting with the valve tissue. This enables us to perform ex vivo and in vitro tests of different valves. Our experimental approach is complemented by computer models for fluid-structure interaction optimized for high-performance computing platforms.

Tomographic PIV behind aortic valve prosthesis

The flow profile in the ascending aorta is strongly affected by the geometry and the condition of the aortic valve. This is also the case if the native valve is replaces with a prosthetic valve, each type influencing the hemodynamics in a specific way. We use a tomographic PIV setup together with a silicone phantom of the aorta and a pulse replicator to tackle flow structures and quantify the shear stresses within the three-dimensional flow field behind a trans-catheter valve implant (TAVI).

 

Contact: David Hasler, MSc.

Bioprosthetic valve performance in compliant aortic roots

Bioprosthetic aortic valves (BAVs) degenerate over time due to calcification and structural deterioration, and the reasons behind are not fully understood. Surgically implanted BAVs are designed in a symmetric, circular fashion to mimic the native valve. While stented BAVs assure undistorted circular implantation due to a rigid stent, sutureless and stentless BAVs implantation might be influenced by the morphology of the patient. This project aims to investigate the impact of patient-specific aortic root parameters on valve kinematics and hemodynamic performance of BAVs.

High performance numerical analysis of AV hemodynamics

Our group aims at full characterization of heart valve hemodynamics. In parallel to in-vivo and in-vitro analysis, we work on developing a tool for numerical fluid-structure interaction analysis. Working in-silico provides the benefit of obtaining quantitative and reproducible data whitout relying on clinical tests such as animal experiments. Our code will be targeted at newly emerging hybrid node supercomputer architectures. Eventually, the library shall be made available to other researchers working in Biofluiddynamics.

Hemodynamics in the pivoting area of the Triflo heart valve

Our research is targeted towards the investigation of the hemodynamics in the hinge region of a novel trileaflet mechanical heart valve prosthesis.  Micro particle image velocimetry (µPIV) offers a scientific tool to investigate the flow on a small scale in an in vitro setup. An experimental configuration was built that allows to simulate the function of the heart and the cardiovascular system and to study the hemodynamics of the mechanical heart valve throughout the cardiac cycle.

Mitral valve repair

Acute posterior leaflet prolapse of the mitral valve can be surgically or minimal-invasive repaired with various techniques. The comparison of the different repair methods are difficult in-vivo due to limited accessability and differences between patients. To avoid these problems, we are conducting different valve repair methods on mitral valves from pigs and we aim to quantitatively compare different mitral valve repair strategies in terms of flow and pressure conditions in a physiological pulsatile in-vitro setup.