TAA 23. Endovascular Creation of Acute in Vivo Swine Model and Multimodality Imaging for Understanding the Pathophysiology of Type B Aortic Dissection

Type B aortic dissection is an aortic wall disease with high morbidity and mortality rates that remains poorly understood, especially in terms of parameters that accurately predict vessel wall instability and aortic remodeling. The aim of this study was to create an in vivo swine model of type B aortic dissection and to understand its pathophysiologic mechanism using multimodality imaging techniques. After gaining of arterial access, the outer aortic wall distal to the left subclavian artery was punctured obliquely using a combination of BRK trans-septal needle (Abbott Vascular, Abbott Park, Ill) and OffRoad (Boston Scientific, Marlborough, Mass) re-entry catheter system under transesophageal echocardiography (TEE), fluoroscopy, and cone beam computed tomography image guidance. After confirmation, heparinized saline was mixed with iodinated contrast material and injected to create hydrodissection within the aortic media. After balloon dilation, administration of phenylephrine bolus and infusion was started to induce hypertension to facilitate distal propagation of aortic dissection. On confirmation by TEE or intravascular ultrasound, a series of imaging studies including cone beam computed tomography, four-dimensional TEE, and magnetic resonance imaging were performed to image the aortic dissection. On completion, the animal was euthanized and the aorta harvested for histopathologic examination. Twelve animals (mean weight, 80.3 kg) were included in this study, and 10 were female. There were no difficulties with vascular access. In three cases (25%), aortic dissection distal to the subclavian artery was created successfully (6, 8, and 8 cm long). This was confirmed with multimodality imaging and histopathologic examination (Figs 1 and 2). In five (41.7%) cases, the animal died of puncturing through the aortic wall. In four cases (33.3%), a hematoma was created within the aortic wall without aortic dissection. Endovascular creation of type B aortic dissection in a swine model consistently and with reproducibility was challenging. Various lessons have been learned and will be implemented in the next phase of this experiment. Ability to access the aortic wall with precise depth and stability seems to be a critical factor in determining the success of creation of aortic dissection.Fig 2Histopathology images with visualization of the entry tear of the aortic dissection with true and false lumen.View Large Image Figure ViewerDownload Hi-res image Download (PPT)