Computational Assessment of Bioprosthetic Aortic Valve Function

Comparing the In-vivo Haemodynamic and Biomechanical Performance of Rapid-deployment Edwards Intuity Elite System and Edwards Magna Ease Valve

Bioprosthetic valves are usually made of biological tissue that are mounted to a frame and are designed to function similarly to a healthy natural valve. Edwards Magna Ease and Intuity Elite bioprosthetic valves have similar leaflets and mounting designs. However, the valves are implanted in the patient in different ways (one is stitched to the wall of the left ventricular outflow tract, and the other is held in place by the radial force of the valve skirt). The study aims to understand in more detail how the different valves interact with the left ventricular outflow tract and aortic root.

The implantation of a bioprosthetic valve is the established surgical technique when replacing the aortic valve to treat various aortic valve diseases. Many different bioprosthetic valves are available. The design and implantation technique in each system would result in different interaction with the left ventricular outflow tract (LVOT) and the aortic root, leading to different flow profiles that may induce platelet aggregation and affect the long-term performance of the bioprosthesis and its durability. Additionally, complications such as valve thrombosis may occur. However, it is not currently clear which bioprostheses/patients are more prone to thrombosis or degradation of the valve. This study aims to develop fluid-structure interaction (FSI) models, which can model blood flow and wall/valve mechanics, using realistic patient-specific geometries and flow conditions which correlate with the true performance of the valve in the imaged patients, and to assess and compare such performances to understand the benefits and challenges with various bioprosthetic valves.

FSI models combine computational fluid mechanics (CFD) with structural wall mechanics modelling. This is an alternative approach that allows detailed assessment of flow patterns and estimation of wall shear stress and pressure within blood vessels, and therefore has been applied increasingly to gain better insights into the hemodynamics in cardiovascular diseases

Inclusion Criteria:

• Male and female patients aged 18 years or over.
• Patients diagnosed with aortic valve disease, and scheduled to undergo Edwards Magna Ease or Intuity Elite and free of exclusion criteria below.
• The patient is willing and able to understand the Patient Information Sheet and provide written informed consent.
• The patient must agree to comply with the study imaging protocol as required at prespecified times.

Exclusion Criteria:

• Inability to provide valid informed consent.
• Male and female patients aged < 18 years of age.
• Contraindications for CT angiography: renal failure (Cr>250 μmol/L or eGFR<30 mL/min) due to the additional risk of contrast medium nephrotoxicity or allergy to iodine.
• Women of childbearing age who have not had a hysterectomy and/or who may be breastfeeding.
• History of cardiac pacing device insertion, or any other MRI incompatible device implants.