P6.08 EVALUATING THE HEMODYNAMIC IMPACT OF ISOLATED NON-DISTENSIBILITY AND RESIDUAL NARROWING AFTER COARCTATION REPAIR USING A COMPUTATIONAL STUDY

Abstract

Background: Even after successful treatment of aortic coarctation, a high risk of cardiovascular morbidity and mortality remains. Uncertainty exists on the factors contributing to this increased risk among others the presence of (1) a residual narrowing, leading to an additional resistance in the arterial system and (2) a non-distensible zone, disturbing the buffer function of the aorta. As the many interfering factors and adaptive physiologic mechanisms present in vivo prohibit the study of the isolated impact of these individual factors, an advanced computer model was developed. Material and methods: The geometry and flow boundary conditions are obtained from MRI data of a healthy subject (Figure 1). A segment with varying length and stiffness was included distal to the left subclavian artery (red zone in Figure 1). Recurrent coarctation was studied by altering the diameter (coarctation index of 0.5 for severe and 0.65 for mild coarctation). Results: Figure 2 depicts the effect of a local non-distensibility on the pressure evolution proximal and distal to the rigid zone. Data shown represent the presence of a stent (length 5cm, 100 × stiffer than reference material) or scar tissue (length 5 mm, 5× stiffer). Although the overall impact is very limited, the presence of a stent increased the proximal systolic pressure with 4.5 mmHg compared to the pressure in a healthy subject. Conclusion: The model allows to study the isolated effect of local non-distensibility and narrowing which is impossible to obtain in vivo. Figure 1Patient specific model. Figure 2Proximal and distal pressure.