In this seminar, I discuss three types of applied research in which collaborations between biomedical engineers and medical doctors can advance the surgical field of vascular grafting. First, I describe a mock circulatory system designed to simulate regional hemodynamics and input impedance in the human aorta. This circuit can estimate the cardiac work that results from implanting or replacing a synthetic aortic graft. Simulation shows that replacement of an aortic graft made of silicone rubber with one made of polytetrafluoroethylene (PTFE) increases cardiac work significantly. Second, I show how technology originally developed for neurosurgical navigation can be applied to the replacement of a thoraco-abdominal aortic aneurysm with a PTFE graft. Here, a registration method combines visual relationships between the real operative space and a three-dimensional space constructed from images obtained by computed tomography. The system employs a phantom thoraco-abdominal artery to accurately locate the Adamkiewicz artery that often, but not always, arises from a left inferior intercostal artery. To date, this navigation system has contributed to the surgical success of eighty-six aortic grafts. Third, I introduce a computational fluid dynamic (CFD) program to predict the distribution of blood flow in a three-branch graft during thoracic endovascular aortic repair (TEVAR). Phase-contrast magnetic resonance angiography image (PC-MRI) of the blood flow distribution determines the initial conditions in patients and healthy individuals. Calculations show a permissible 3% decrease in flow in the descending aorta after surgical endovascular debranching. Finally, I emphasize the importance of educating and training new leaders of Medical Regulatory Science to achieve a true engineering-medical collaboration at Tokyo Women’s and Waseda University Joint Institution for Advances Biomedical Sciences.

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We experienced successful treatment of a case with prosthesis infection after the femoro—popliteal artery bypass. Prior to the partial removal of infected prosthesis graft, endarterectomy and patch angioplasty of the orifice of superficial femoral artery using the remnant vascular graft was performed. This technique was useful for the wire access to the occluded superficial femoral artery during the revascularization to be performed later. It also could be avoid compromising the deep femoral artery origin and eliminate the need for stenting near the groin crease. The improved blood flow of lower extremity was maintained, and we had not observed any reinfection in our patient during the 2-year follow-up period. This technique may be an alternative approach in the treatment of prosthesis infection and the revascularization for occluded femoral artery.

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Surgical treatment of acute aortic dissection in a patient with acute cerebral hemorrhage is rare. A 65-year-old man was diagnosed as having cerebral hemorrhage with right hemiplegia and aphasia. Furthermore he was diagnosed type A acute aortic dissection. Emergency surgery with cardiopulmonary bypass was contraindication for acute cerebral hemorrhage. After he got hypotension care for two weeks ascending aorta replacement was conducted. Postoperative coarse was stable. He was discharged on postoperative day 14 without worsening of right hemiplegia or dysphasia.

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A 78-year-old man presented at a clinic 2 years previously with angina. Coronary computed tomography (CT) angiography revealed a saccular aneurysm of the descending aorta. The patient was referred to our hospital where he underwent thoracic endovascular aneurysm repair. Two years later, he was admitted to a nearby hospital with a fever and a body temperature of 38°C. Tests showed elevated white blood cell count and C-reactive protein level, and the patient was administered antibiotics and referred to our hospital. CT revealed thickening of the stent-graft outer aortic wall and expansion of the contrast effect compared with that on the previous scan. Therefore, we suspected infection of the aortic wall and the patient underwent surgery to remove the stent-graft, excise the aortic wall, and replace the descending aorta to the graft. On postoperative day 11, the patient was discharged. He experienced no recurrence of infection for 6 months postoperatively. Careful postoperative follow up is necessary following placement of a stent-graft for saccular aneurysm.

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A 77-year-old man, presented with chest and abdominal pain, was diagnosed with aortic dissection with severe stenosis of the celiac artery and superior mesenteric artery (SMA) and obstruction of the inferior mesenteric artery and left common iliac artery on computed tomography. Replacement of the ascending aorta was performed but the entry was not resected. He underwent sigmoid colon resection and colostomy due to necrosis on postoperative day 1 (POD1). Then, the small intestinal tone returned to normal, and good flow in the SMA was observed by collar Doppler ultrasonography. However, the patient presented with extensive intestinal ischemia on POD2. Surgical treatment was not performed due to the presence of large intestinal ischemia. Then, the intestinal ischemia improved with only conservative treatment, and the intestinal appearance was found to be almost normal in exploratory laparotomy on POD10. He was transferred to another hospital for rehabilitation, and he is currently visiting our hospital as an outpatient without a sequelae.

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A 60-year-old male who had a history of receiving multiple vascular surgeries, including aorto-bifemoral bypass (ABF) for Leriche syndrome at the age of 32, redo arterial reconstruction for acute arterial thrombosis in the right rim of ABF graft at the age of 55, and endovascular aneurysm repair (EVAR) for pseudoaneurysm formed at the proximal anastomosis at the age of 56. He was admitted to our department, complaining of the enlarged pulsatile mass in the right groin at the age of 60, and was diagnosed with aneurysmal dilatation of the right rim of ABF graft. Intraoperative findings revealed the anterior wall of the prosthetic rim was completely destroyed, and covered with the surrounding tissues. Graft replacement of the right rim of ABF graft with the uses of ePTFE graft along with wrapping the remaining rim, including the clamp site was performed for the prevention of aneurysmal redilatation of the old conduit. He was discharged home 10 days after surgery. Performance of imaging evalutation on a regular basis from now on is considered to be imperative to diagnose the aneurysnal dilatation of prostheis caused by its structual deterioration.

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We report a successful case of ruptured abdominal aortic aneurysm with horseshoe kidney treated by graft replacement following the insertion of an aortic occlusion balloon catheter. An 80-year-old man, presenting with sudden abdominal pain, was transferred under the diagnosis of ruptured abdominal aneurysm. Enhanced CT showed infrarenal abdominal aortic aneurysm, retroperitoneal hematoma, and horseshoe kidney. As soon as possible, we performed indwelling aortic occlusion balloon catheter via a femoral artery under radiographic guidance. At the time of induction of anesthesia, because of the collapse of hemodynamics, we inflated the balloon to stabilize the patient's blood pressure, and performed the bifurcated graft replacement and inferior mesenteric artery reconstruction with preserved isthmus of horseshoe kidney in safety. The postoperative course was uneventful, and the patient was discharged on the 14th postoperative day without any morbidity.

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Ruptured thoracic aortic aneurysm (rTAA) is a condition with a high fatality rate that requires emergency surgery. Recently, thoracic endovascular aortic repair (TEVAR) has emerged as an alternative to open repair. This report describes a case of a 96-year-old woman who underwent successful TEVAR for rTAA. The patient developed chest pain and was transported to the hospital via ambulance. Computed tomography scan revealed a rupture site at the distal arch as well as left hemothorax. Two thoracic stent grafts were deployed to successfully exclude the rupture. A left chest tube was placed, and hematoma removal from the left thoracic cavity was performed via small thoracotomy 16 days later. Her postoperative course was uncomplicated, and on day 41, she was transferred to a rehabilitation facility. We conclude that TEVAR is an effective procedure for the management of thoracic aorta aneurysms in elderly patients.

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Endovascular aneurysm repair (EVAR) is an attractive management of the abdominal aortic aneurysm, however it is difficult modality to treat the aortoiliac aneurysms involving the both common iliac arteries. We successfully performed comcomitant EVAR and external-internal iliac artery bypass using venous graft for a case of aortoiliac aneurysm. The patient was a 68-year-old male presenting with abdominal aortic aneurysm. It’s maximum diameter was 34 mm and bilateral iliac artery aneurysms (right 56 mm, left 47 mm) in abdominal computed tomography (CT) and it was found accidentally during survey for rectal cancer. He had rectal cancer and multiple liver metastases, therefor the operative risk of open surgery was judged to be high, and recovery of his physical activity would take a long time. Also, intraperitoneal adhesion would exceed operation time and the increase the risk of vascular prosthetic infection. Then, the simultaneous EVAR and external-internal iliac artery bypass using autogenous saphenous vein graft was proposed. We needed to avoid ischemia of the rectum and combined EVAR and external-internal iliac artery bypass was performed concurrently. The postoperative course was uneventful. Six months after surgery, abdominal CT revealed no endoleak and internal iliac artery bypass graft was patent without any problems. He did not complain symptoms of ischemic colitis or buttock claudication. The EVAR with external-internal iliac artery bypass was less invasive and extremely effective for the treatment of abdominal aortic aneurysm with bilateral iliac artery aneurysms.

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Popliteal venous aneurysm (PVA) is a rare, but potentially life-threatening disease because it can be a source of pulmonary embolism (PE). We present our experience of a case with PVA associated with repeated PE. A 68-year-old man complaining of dyspnea was admitted to our hospital with a diagnosis of bilateral PE. In spite of sufficient anticoagulant and thrombolytic therapy, PE recurred 7 days after the admission. A permanent inferior vena cava filter was placed for preventing fatal PE. Thereafter, CT and ultrasonography revealed the existence of PVA. After the diagnosis, we performed the resection of aneurysm and patch plasty. The patient has had no episode of thrombus recurrence for 6 years since the operation.

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We report a patient who developed disseminated intravascular coagulation (DIC) following a type 1a endoleak after an endovascular aneurysm repair (EVAR) for an abdominal aortic aneurysm (AAA), and who improved after open surgery. An 82-year-old woman underwent EVAR for a 50-mm infrarenal AAA in July 2012. Argatroban was used as anticoagulant because she had a history of heparin-induced thrombocytopenia. Postoperatively, a type 4 endoleak was present. Three months after the EVAR, she was admitted due to severe anemia and DIC. Computed tomography showed an endoleak with no evidence of an increase in size of AAA and huge intramuscular hematoma in her right thigh. The DIC was treated medically, but when the thrombomodulin was stopped, the thrombopenia progressed. Since no other cause of the DIC was found, we diagnosed that a consumption coagulopathy in the aneurysm sac was occured. She was re-treated to stop the leak completely. Angiography showed a type 1a endoleak. The volume of the endoleak was minimized but not disappeared following placement of a cuff and extra-large stent in the proximal neck, and then we proceeded with open psurgery to eliminate the leak completely. Postoperatively, the DIC improved and has not returned.

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