A clinical example – how modelling may improve clinical practice

A 23 year old female patient with a native bicuspid aortic valve (congenital heart disease) and with a di- lated ascending aorta. This is associated with aortic valve disease and the proposed treatment is an aortic valve replacement. The choice of a proper valve replacement is challenging. When biological valves are used they could fail several years after implantation due to lower durability, whereas mechanical prostheses have better durability but require life-long medication which reduces blood clotting.

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Fig. 1: A comparison of haemodynamics after the virtual valve replacement procedure using one biological and a one mechanical valve prosthesis. Path lines are colour coded by a velocity magnitude

Younger paediatric patients will not be suitable for such medication and the choice of a proper valve replacement is also limited by the fact that they will still grow. Using a computer model of the patient’s cardiac system, we performed two virtual valve replacements, one using a biological heart valve and one using a mechanical heart valve prosthesis.  Then we analysed the post treatment haemodynamics and compared both possible treatments (see Figure above): the valve replacement using biological valve prosthesis causes, according to the modelling software, an ascending aorta entrance jet directed toward the lateral wall that forms a strong secondary flow (swirl) associated with high velocity magnitudes near the wall. In contrast, the mechanical valve forms a jet located at the centre of the ascending aorta with lower velocities near the aortic wall. Higher velocities near wall are associated with higher force acting on the aortic wall that is supposed to promote an aortic dilatation. In this light, the mechanical valve seems to be the favourable treatment solution.

This article was originally published in Cardioproof Newsletter-Issue 1

Author: Titus Kühne