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Insulin Delivery by a Bioartificial Pancreas
Published in Emmanuel Opara, Controlled Drug Delivery Systems, 2020
The pancreas became the fourth organ to be successfully transplanted in humans (following successful transplantation of kidney, liver, and heart).20 On December 17, 1966, W Kelly and R Lillehei’s team at University of Minnesota did a duct-ligated segmental pancreas transplant into 28-year-old uremic female patient.21 The patient developed graft pancreatitis and the rejected kidney and pancreas ultimately had to be removed, and the patient died from pulmonary embolism, 13 days after the transplanted grafts were removed.21 She did, however, have six insulin-free days after the transplant was performed.21 Dr Felix Largiader, who was also at the University of Minnesota, in 1967, then successfully transplanted the whole pancreas with attached duodenal cuff in a canine model.22 He connected the donor celiac artery to the host aorta, the donor portal vein to the vena cava, oversewed one end of the duodenum, and connected the other end of the duodenum to a roux-en-y jejunal segment.22 Later that same year, Dr Lillehei successfully adopted the same technique to human transplants.22 With evolution and refinement of surgical techniques, introduction of first cyclosporine and then other immunosuppressants, as well as better Human Leukocyte Antigen (HLA) matching techniques, the outcomes of pancreas transplants have significantly improved since the first 14 were performed at the University of Minnesota.23
Digital Subtracted Angiography of Small Animals
Published in George C. Kagadis, Nancy L. Ford, Dimitrios N. Karnabatidis, George K. Loudos, Handbook of Small Animal Imaging, 2018
Stavros Spiliopoulos, George C. Kagadis, Dimitrios N. Karnabatidis, G. Allan Johnson, Cristian Badea
Placement of the catheters is critical for producing high-quality DSA images. Various access ports for contrast agent injections have been used depending on the target organ. We provide here a few examples of catheter placements. For cardiopulmonary DSA imaging, the catheter was placed in the right jugular vein at the root of the superior vena cava (De Lin et al. 2006, 2008; Lin et al. 2009). For coronary DSA imaging, the catheter was inserted into the right common carotid artery and advanced into the aortic arch. The catheter tip was positioned just cranial to the aortic valve using real-time blood pressure guidance (Badea et al. 2011). The common carotid artery and femoral artery have been used quite often for catheter placement (Kissel et al. 1987; Lin et al. 2009; Ortiz-Velazquez et al. 2009; Buhalog et al. 2010; Figueiredo et al. 2012). In DSA imaging of the liver, two catheter placements have been reported (Badea et al. 2013). The first catheter was used to visualize the portal vein system and was inserted through a mesenteric vein and advanced into the portal vein. To view the arterial system, a second catheter was placed into the left common carotid and into the abdominal aorta just above the celiac artery. In DSA imaging of the kidneys (see Figure 6.4), the catheter was placed in the iliac artery so that the tip was at the level just distal to the left renal artery. Facial and tail artery access points have also been described (Ortiz-Velazquez et al. 2009). Buhalog et al. developed a very interesting technique for performing sequential arterial catheterizations and DSA in rats, after the intra-arterial placement of a microcatheter through a sheath positioned using a transfemoral microsurgical approach (Buhalog et al. 2010).
Hemodynamic analysis of hybrid treatment for thoracoabdominal aortic aneurysm based on Newtonian and non-Newtonian models in a patient-specific model
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2023
Jun Wen, Jiarong Wang, Liqing Peng, Ding Yuan, Tinghui Zheng
As shown in Figure 1a, the inflow site for visceral bypass was at distal AA. In addition, visceral and renal arteries were ligated at the origin to avoid back-flow in the aneurysm and the risk of type II endoleak. Four-bifurcated visceral grafts, respectively connected to the right renal artery (RRA), superior mesenteric artery (SMA), celiac artery (CA), and left renal artery (LRA) were marked in Figure 1b. The geometrical features of the patient-specific RVR including the diameters of proximal TA, distal AA, LCIA and RCIA are approximately 32, 17.5, 7.5, and 7.8 mm, respectively. In addition, the diameters of the main trunk and branch grafts (CA, SMA, LRA, and RRA) of the visceral bypass are approximately 15.4, 5.8, 5.4, 3.2, and 4.2 mm, respectively. Moreover, the anastomotic angle between the AA and the main trunk of bypass grafts is approximately 62°. Based on a 20-day postoperative ultrasound follow-up report of this patient, atherosclerotic plaques can be observed in the infrarenal AA region (region A), as shown in Figure 1d, where the plaques were marked with blue oval, while there were no atherosclerotic plaques reported in the anastomosis region (region B).
A modified method of computed fluid dynamics simulation in abdominal aorta and visceral arteries
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2021
Yun Shi, Chen Peng, Junzhen Liu, Hongzhi Lan, Chong Li, Wang Qin, Tong Yuan, Yuanqing Kan, Shengzhang Wang, Weiguo Fu
Les et al. reconstructed patient-specific AAA models including the visceral arteries, and measured the flow rates of supra-celiac (SC) and IR aorta by 2D PCMRI. The difference of flow rates between SC and IR aorta was assigned to the celiac artery (CA), superior mesenteric artery (SMA) and bilateral renal arteries (RA) according to the percentage from literature (Suh et al. 2011). However, the flow rates assigned to visceral arteries were unlikely accurate since they were not measured values. To overcome this defect, we measured the flow rates of not only SC and IR aorta but also CA, SMA, bilateral RAs for a volunteer by 2D PCMRI. The imaging planes of 2D PCMRI were roughly the ends of SC aorta, IR aorta, CA, SMA and bilateral RAs of the patient-specific 3D geometric model (Figure 1a). The flow BC was imposed on the inlet of SC aorta and the outlets of visceral arteries, the RCR BC was imposed on the outlet of IR aorta to run the CFD simulation (Figure 1b), which will be detailed in Section 2.3.
Flow analysis of aortic dissection: comparison of inflow boundary conditions for computational models based on 4D PCMRI and Doppler ultrasound
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2021
Zhenfeng Li, Shichao Liang, Huanming Xu, Minjia Zhu, Yuqian Mei, Jiang Xiong, Duanduan Chen
The current study focused on investigating the influence of the IBCs on the downstream flow system of AD. All the outlets of the models were thus unified. Velocity information of the three aortic arch branches was extracted from 4D PCMRI of the patient case, as shown in Figure 2b. Approximately 12.7% of the inlet flow volume was diverted to brachiocephalic trunk, while 3.2% and 3.1% of the inflow were diverted to the left common carotid artery and left subclavian artery respectively. Generally, they presented the parabolic velocity profile and the time-variant flow waveforms could be captured by the 4D PCMRI. Detailed information regarding the personalized flow division was displayed in S4, Supporting Document. Apart from the aortic arch branches, the outlets of the celiac artery, superior mesenteric artery, renal arteries and the common iliac arteries were assigned as the pressure outlets. So far, non-invasive pressure measurements of these sites were not available. A few computational studies applied the pressure data that were published previously(Tse et al. 2011; Naim et al. 2016). Here we applied the pulsatile pressure waveforms that were also used in our previous study (Vignon-Clementel et al. 2006). Its rationality was discussed in S5, Supporting Document.