Morphometric analyses to study risk factors in thoracic aortic diseases

Abstract

In this dissertation, two main aortic pathologies, aneurysmal and dissections, can both be treated with thoracic aortic endovascular repair (TEVAR). TEVAR is the treatment of choice, due to a fast recovery period after surgery and its suitability for the high-risk patient who is unfit for open surgery. However, the human anatomy is not always suitable for endovascular repair. In this dissertation, you find an overview of the limitations of devices that are used in endovascular repair. A summary of large trials investigating the difference in open surgery and endovascular aortic repair (EVAR), as well as considerations for the imaging modalities used preoperatively, perioperatively and postoperatively, and finally complications and the evolution of devices. Focusing on the descending thoracic aorta (DTA) and its complications a systematic review is performed on type 1b endoleaks. This is followed by studies on aortic tortuosity in the DTA. First describing tortuosity in a healthy patient population between young (< 65) and older (> 65) patients, where older patients have a higher tortuosity index. Then, comparing a healthy population to patients with aneurysmal diseases and dissections. Patients with aneurysmal diseases have the highest amount of tortuosity. The final paper on aortic tortuosity describes the displacement forces throughout the DTA, divided into four equal zones, in three groups with a different amount of tortuosity (low = <30º; moderate = 30º - 60º; high = >60º). The high tortuosity group has the strongest displacement force. The following section is on aortic dynamics in the ascending thoracic aorta (ATA). Additional measurements for optimal endograft sizing are needed in the ascending aorta (Z0). Normally, based on the diameter the right endograft size is calculated and used for TEVAR. However, in Z0 the aortic dynamics are more extreme going from a circle shape to an oval in one cardiac cycle. Measurements were taken from electrocardiography (ECG)-gated computed tomography (CT) scans. The area has a smaller delta in the cardiac cycle than the diameter. The next chapter describes the aortic dynamics after stent graft deployment in the ascending aorta. The aorta becomes stiffer at the location where the stent-graft is deployed, however, proximal to the stent-graft the aorta is more compliant. The final section consists of studies related to education in vascular surgery. The first chapter validates a model, which was developed to test performance in endovascular trainees. The model consistently differentiates novices from experts based on their smoothness and velocity in handling the guidewire and catheter. Then about Endotherapy in IMH and dissections. An overview of the imaging modalities that are used for treatment and the tools necessary for endovascular repair. Finally, the endovascular creation of a swine model for type B aortic dissection. The aim is to study the pathophysiology using multi-modality imaging and to create a surviving model to test future treatment options. Due to aortic wall motion and wall thickness, it was challenging to create this model consistently and with reproducibility. However, multi-modality imaging was very useful as aortic dissection is a dynamic disease.