CFD Challenge: Predicting Patient-Specific Hemodynamics at Rest and Stress through an Aortic Coarctation

Background Coarctation of the aorta (CoA), a narrowing of the aorta, accounts for approximately 10% of congenital heart defects in the western world. Due to the reduction in diameter, high pressure gradients can appear across the aortic coarctation, resulting in an increased cardiac workload. Current therapies, either surgical or minimally-invasive, aim to alleviate the blood pressure gradient through the coarctation. The pressure gradient is dependent on the severity of the aortic narrowing: the greater the percentage of area reduction, the larger the pressure gradient. The pressure gradient is also highly dependent on the flow rate, and therefore the physiologic state of the patient: a small pressure gradient at rest can increase several-fold even in mild stress conditions. For these reasons, it is critical to assess the blood pressure gradient during exercise induced stress, for an accurate diagnosis. As opposed to the routine assessment during resting conditions, , measuring the pressure gradient under exercise conditions is more challenging since these conditions are not easy to replicate in the clinic. ‘Pharmacological stress-test’ is sometimes performed. However, besides the limitations in replicating other mechanisms present in real exercise conditions, such as alterations in peripheral vascular resistance, the stress tests are not ideal for the patient since they often present side-effects such as palpitations, chest pain, shortness of breath, headache, nausea or fatigue.