Development of an Undifferentiated Pleomorphic Sarcoma After Aortic Aneurysm Graft Replacement: A Case Report and Literature Review.

Aortic sarcomas are extremely rare. Sarcomas associated with aortic graft replacement are even rarer; only 17 cases have been examined through immunohistochemical staining to date, most of which were either angiosarcomas or intimal sarcomas. Here, we report the case of an 88-year-old man with an undifferentiated pleomorphic sarcoma (UPS) that developed after aortic graft replacement and was diagnosed through postmortem autopsy. To the best of our knowledge, this is the first case of graft-associated sarcoma diagnosed as an undifferentiated pleomorphic type following detailed immunohistochemical staining with sufficient antibodies and fluorescencein situ hybridization (FISH).

Effects of povidone-iodine wound irrigation on surgical site infection in gastroenterological surgery: A randomized controlled trial.

BACKGROUND: The irrigation efficacy of a povidone-iodine solution to prevent surgical site infection is still controversial. We assessed the irrigation effect with a povidone-iodine solution on the incidence of surgical site infection after gastroenterological surgery. METHODS: This study is a single-center, prospective, randomized, blinded-end point superiority trial for surgical wound irrigation. Patients undergoing gastroenterological surgery were randomly assigned in a 1:1 replacement ratio using computer-generated randomization. Patients were grouped according to their surgical wound treatment into the control group using the normal sterile saline and the povidone-iodine group using 10% povidone-iodine solution after the NS solution. The main finding was 30-day surgical site infections assessed in the full analysis set. RESULTS: From November 2020 to December 2022, 697 of 894 patients were eligible for the study, among which 347 were in the povidone-iodine group and 350 in the control group. Thirty-day surgical site infections occurred in 100 (14%) patients-54 (16%) in the povidone-iodine group and 46 (13%) in the control group (odds ratio, 1.229; 95% CI, 0.800-1.889; P = .406). Superficial incisional surgical site infections occurred in 30 (9%) and 15 (4%) patients, respectively (odds ratio, 2.154; 95% CI, 1.134-4.090; P = .026). Only 3 patients (1%) in the control group developed adverse skin reactions. CONCLUSION: This study examined the irrigation efficacy of povidone-iodine for surgical site infection prevention compared to control in gastroenterological surgery. Povidone-iodine wound irrigation has shown no additional beneficial effect on the occurrence of surgical site infections.

Risk and Prognosis of Upper Extremity Deep Vein Thrombosis.

Objectives: We aimed to investigate the clinical features of upper extremity deep vein thrombosis (UEDVT). Methods: We retrospectively reviewed the background, thrombus site, treatment, and outcome of 76 UEDVT patients. Results: Of the 76 UEDVT patients, 44 (57.9%) were men, and 51 (67.1%) were complicated by malignancy, 44 (57.9%) had an indwelling central vein (CV) catheter, 8 (10.5%) had concomitant pulmonary embolization (PE), and 33 (43.3%) were symptomatic. Regarding the thrombus site, the right internal jugular vein was the most common, with 30 cases (35.3%). As regards the treatment method, 53 patients (69.7%) received oral anticoagulants. In 2015, when direct oral anticoagulants (DOACs) was covered by insurance, there were 44 UEDVT cases, of which 34 (77.3%) received DOACs. Outcomes at a mean observation period of 37.5±41.5 months included 40 deaths (52.6%) with a mean survival of 16.3±21.3 months. The most common cause of death was malignancy, with 33 cases (82.5%). Conclusion: In the background of UEDVT, the combination of indwelling CV catheter placement and malignancy was frequently observed. While the risk of recurrence or PE complications is low, the prognosis of UEDVT complicated by malignancy is extremely poor.

Real-Time Assessment of Tissue Oxygen Saturation Using a Novel Oximeter During Revascularization for Acute Limb Ischemia: A Case Report.

Emergency surgery was performed to treat acute lower limb ischemia caused by heart thromboembolism and concomitant popliteal artery aneurysm. Using a near-infrared spectroscopy oximeter, regional tissue oxygen saturation (rSO2) was monitored to assess the tissue perfusion pre-, intra-, and postoperatively. rSO2 values did not increase sufficiently following thromboembolectomy of the superficial femoral artery, but they dramatically recovered after additional popliteal-anterior tibial bypass surgery. The affected limb was successfully salvaged. rSO2 monitoring was easily measured intraoperatively, which might be beneficial in evaluating tissue perfusion in patients with acute limb ischemia.

Pre-Operative Four Dimensional Flow Sensitive Magnetic Resonance Imaging Assessment of Aortic Side Branches as a Method to Predict Risk of Type II Endoleak Resulting in Sac Enlargement After EVAR.

OBJECTIVE: To predict sac enlargement with type II endoleak (ELII) before endovascular aneurysm repair (EVAR) using four dimensional flow sensitive magnetic resonance imaging (4D flow MRI). METHODS: A single centre retrospective analysis of prospectively collected data was conducted. Patients with an abdominal aortic aneurysm (AAA) who underwent EVAR between 2013 and 2019 were included. Aortic branches occluded pre-EVAR, and patients with endoleaks other than ELII were excluded. The aortic branch diameter, peak flow velocity (PFVe), and amplitude of the dynamics of flow volume (AFV) were measured in each aortic branch pre-EVAR. Total flow volume per minute (TFV/min), defined as the sum of AFV/min, was calculated in each case. According to computed tomography findings one year post-EVAR, the aortic branches and patients were divided into patent vessel and occluded vessel groups and sac expanding and non-expanding groups. PFVe, AFV/min, and TFV/min were analysed via receiver operating characteristic curve analysis. RESULTS: The patent aortic branches pre-EVAR (69 inferior mesenteric arteries [IMAs]; 249 lumbar arteries [LAs]) of 100 patients were included. Patent IMAs (n = 14) and occluded IMAs (n = 55), patent LAs (n = 23) and occluded LAs (n = 226), and expanding (n = 9) and non-expanding (n = 91) groups were compared, respectively. No statistically significant difference was observed in branch diameters (IMA; patent, 2.5 ± 0.8 mm, occluded, 2.5 ± 0.8 mm, p < .78 and LA; patent, 1.5 ± 0.3 mm, occluded, 1.5 ± 0.4 mm, p < .35). PFVe (IMA; patent, 262.6 mm2/sec, occluded, 183.4 mm2/sec and LA; patent, 142.6 mm2/sec, occluded, 47.7 mm2/sec) and AFV/min (IMA; patent, 8.4 mL, occluded, 5.2 mL and LA; patent, 4.2 mL, occluded, 1.4 mL) were higher in the patent vessel group (p < .050). TFV/min was statistically significantly higher in the expanding group (24.1 mL/min) than in the non-expanding group (7.0 mL/min) (p < .010). CONCLUSION: Pre-EVAR haemodynamic analyses using 4D flow MRI were useful to detect aortic branches responsible for ELII and to predict AAA cases with sac enlargement. This analysis suggests a new strategy for pre-EVAR aortic branch embolisation.

Survey of Food Intake in Patients with Abdominal Aortic Aneurysm.

Abdominal aortic aneurysm (AAA) is a vascular disease that involves asymptomatic progressive expansion of the abdominal aorta. Aneurysm rupture is associated with a high mortality rate. Dietary conditions may be associated with the development and rupture of AAA. However, the relationship between nutrition and AAA is not completely understood. In this study, a nutrition survey was conducted using a brief self-administered diet history questionnaire (BDHQ) to evaluate the relationship between AAA and dietary habits. One-hundred and twenty-six Japanese people participated in the nutrition survey. Food intake status was analyzed in four groups: the analyzed group-1 (all men), analyzed group-2 (men with smoking history), analyzed group-3 (all women) and analyzed group-4 (women without smoking history). In group-2 and group-3, the intake of citrus fruits was significantly lower in the AAA group than in the non-AAA group. In group-2, the intake of soybean and soybean products was significantly lower in the AAA group than in the non-AAA group. In analyzed group-3, the intake of other vegetables (vegetables except for green and yellow vegetables and soybeans) and seafood was significantly lower in the AAA group than in the non-AAA group. This study suggests that AAA onset may be associated with low intake of fruits, soybeans, vegetables, and seafood.

Characteristics and Prognostic Factors of Venous Thromboembolism in Cancer Patients.

Background: Improving the prognosis of patients with malignant tumors is increasing the number of patients who develop venous thromboembolism. We examined the characteristics and prognostic factors of VTE patients with cancer. Methods: We diagnosed 725 VTE patients from April 2005 to March 2018. There were 322 cancer associated patients (CAT) and 403 non-cancer associated patients (nonCAT). We examined characteristics and prognostic factors of VTE in CAT patients. Results: There were 156 women and 166 men in CAT, and 132 women and 271 men in nonCAT. There was no significant difference in the location of proximal portion of thrombus. When locations were divided into left leg, right leg, and bilateral legs, bilateral cases were more common in CAT group. Comparing the overall survival after VTE diagnosis in the CAT group, the prognosis was poor in patients with high D-dimer level (≧6 µg/mL) along with cancer metastasis and recurrence. Conclusions: Various VTE factors predict prognosis in CAT patients, and CAT is important in the treatment of cancer patients. (This is secondary publication from Jpn J Phlebol 2020; 31(3): 153-159.).

Real-time assessment of tissue oxygen saturation during endovascular therapy for chronic limb threatening ischemia using a novel oximeter.

In the present study, we have introduced a novel real-time, near-infrared spectroscopy oximeter, the TOE-20 (Astem, Co, Ltd, Kawasaki, Japan), which can simultaneously measure the regional tissue oxygen saturation (rSO2) in the skin and subcutaneous tissue at three angiosomes of the foot. Seven patients with chronic limb threatening ischemia who had undergone successful revascularization of the superficial femoral artery were included. The analysis revealed a significant correlation between the rSO2 and skin perfusion pressure. After revascularization, the rSO2 and skin perfusion pressure had both increased at the three regions, although the increase at the plantar foot was insignificant. These results indicate that the TOE-20 can be successfully used to monitor the rSO2 during endovascular treatment.

Role of Subcutaneous Adipose Tissues in the Pathophysiology of Secondary Lymphedema.

Background: Secondary lymphedema (LE) occurs due to the disruption of lymphatic circulation. Lymphatic fluid accumulation in subcutaneous tissues induces adipocyte proliferation. Obesity is an important risk factor for the occurrence and deterioration of LE. Although the relationship between LE and subcutaneous adipose tissue increase has been reported clinically, their pathophysiological relationship remains unknown. Thus, we aimed to verify whether subcutaneous adipose tissue increase is involved in the pathophysiology of secondary LE. Methods and Results: The hindlimb model of secondary LE was created using male Sprague-Dawley rats (control and LE groups; n = 5 each). Skin samples were obtained on postoperative day 168. Histological examination and quantitative real-time polymerase chain reaction analysis of inflammatory adipokines, tumor necrosis factor-alpha (Tnf-α), C-C chemokine ligand 2 (Ccl2), and interleukin-6 (Il-6) were performed. Limb volume and subcutaneous adipose tissues significantly increased in the LE group compared with those in the control. Macrophages aggregated in the augmented adipose tissues, around the adipocytes, and formed crown-like structures (CLSs). The number of CLSs significantly increased in the LE group. These macrophages expressed transforming growth factor-beta 1 (TGF-ß1). Inflammatory adipokine secretion was not observed. Although Il-6 expression increased in the LE group, IL-6 was expressed in subcutaneous myofibroblasts but not in subcutaneous adipocytes. Conclusion: As TGF-ß1 derived from subcutaneous myofibroblasts is involved in skin fibrosis during LE, TGF-ß1 derived from adipose tissues may also play a similar role. Drug treatment for subcutaneous adipose tissue reduction may improve the skin condition in secondary LE and may be a new therapeutic strategy.

Differences in Vasa Vasorum Distribution in Human Aortic Aneurysms and Atheromas.

The pathophysiological difference between aortic atheromas and aneurysms is unknown. We focused on the vasa vasorum (VV), which play a critical role in maintaining aortic homeostasis and are also involved in vascular diseases. We investigated the differences in VV between the atheromas and aneurysms. Human abdominal aortic samples were obtained from patients with abdominal aortic aneurysm during surgery or autopsy cases. Autopsy cases were divided into 2 groups according to atheromas. The VV were evaluated using immunohistochemical staining for von Willebrand factor. Intimal VV increased in both the atheroma and aneurysm groups, medial VV increased, and adventitial VV decreased only in the aneurysm group. We also observed that the medial VV were connected to the adventitial VV in the atheroma group and to intimal VV in the aneurysm group. We suggest the outside-in VV or inside-out VV theories. Atheroma induces hypoxia of aortic walls, and angiogenic factors might induce an increase of intimal VV derived from adventitial VV (outside-in VV). However, adventitial VV decrease induces hypoxia of aortic walls, and angiogenic factors might induce an increase of intimal VV derived from aortic lumen (inside-out VV). These differences of VV may contribute in elucidating the pathophysiology of aortic diseases.

Recombinant Interleukin-19 Suppresses the Formation and Progression of Experimental Abdominal Aortic Aneurysms.

Background Interleukin-19 is an immunosuppressive cytokine produced by immune and nonimmune cells, but its role in abdominal aortic aneurysm (AAA) pathogenesis is not known. This study aimed to investigate interleukin-19 expression in, and influences on, the formation and progression of experimental AAAs. Methods and Results Human specimens were obtained at aneurysm repair surgery or from transplant donors. Experimental AAAs were created in 10- to 12-week-old male mice via intra-aortic elastase infusion. Influence and potential mechanisms of interleukin-19 treatment on AAAs were assessed via ultrasonography, histopathology, flow cytometry, and gene expression profiling. Immunohistochemistry revealed augmented interleukin-19 expression in both human and experimental AAAs. In mice, interleukin-19 treatment before AAA initiation via elastase infusion suppressed aneurysm formation and progression, with attenuation of medial elastin degradation, smooth-muscle depletion, leukocyte infiltration, neoangiogenesis, and matrix metalloproteinase 2 and 9 expression. Initiation of interleukin-19 treatment after AAA creation limited further aneurysmal degeneration. In additional experiments, interleukin-19 treatment inhibited murine macrophage recruitment following intraperitoneal thioglycolate injection. In classically or alternatively activated macrophages in vitro, interleukin-19 downregulated mRNA expression of inducible nitric oxide synthase, chemokine C-C motif ligand 2, and metalloproteinases 2 and 9 without apparent effect on cytokine-expressing helper or cytotoxic T-cell differentiation, nor regulatory T cellularity, in the aneurysmal aorta or spleen of interleukin-19-treated mice. Interleukin-19 also suppressed AAAs created via angiotensin II infusion in hyperlipidemic mice. Conclusions Based on human evidence and experimental modeling observations, interleukin-19 may influence the development and progression of AAAs.

Kidney transplantation from a living donor with renal artery fibromuscular dysplasia: A case report on arterial grafting of the donor renal artery.

INTRODUCTION: Renal artery fibromuscular dysplasia is generally considered a contraindication of kidney transplantation, since fibromuscular dysplasia occasionally induces hypertension or renal insufficiency in the recipient and/or donor. To date, limited information remains available with respect to whether kidneys with renal arterial fibromuscular dysplasia can be successfully transplanted. CASE PRESENTATION: A 53-year-old potential donor was diagnosed with fibromuscular dysplasia of the right renal artery. Laparoscopic right nephrectomy was performed, and the affected portion was resected and reconstructed using the harvested internal iliac artery. Transplantation was successful and the serum creatinine level was <2 mg/dL for 3 years after surgery. CONCLUSION: If reconstruction of the diseased artery could be safely performed, transplantation using a kidney from a donor with renal artery fibromuscular dysplasia may be considered.

Target region oxygenation-based endovascular treatment in a chronic limb-threatening ischemia patient with multifocal arterial diseases.

Patients with chronic limb-threatening ischemia often have multiple segmental diseases requiring revascularization. However, there is no defined milestone to indicate sufficient endovascular treatment (EVT). Using multiple near-infrared spectroscopic oximeters, we intraoperatively monitored regional tissue oxygen saturation (rSO2) to perform target region oxygenation-based EVT for a patient with chronic limb-threatening ischemia. Stent placement at the superficial femoral artery and angioplasty of the tibioperoneal trunk enabled rSO2 in the target ischemic regions (dorsal foot and heel) to be >50% for ulcer healing. We herein describe target region oxygenation-based EVT with rSO2 monitoring as an effective strategy for performing the minimum requisite procedures.

Potential role of transforming growth factor-beta 1/Smad signaling in secondary lymphedema after cancer surgery.

Secondary lymphedema often develops after cancer surgery, and over 250 million patients suffer from this complication. A major symptom of secondary lymphedema is swelling with fibrosis, which lowers the patient's quality of life, even if cancer does not recur. Nonetheless, the pathophysiology of secondary lymphedema remains unclear, with therapeutic approaches limited to physical or surgical therapy. There is no effective pharmacological therapy for secondary lymphedema. Notably, the lack of animal models that accurately mimic human secondary lymphedema has hindered pathophysiological investigations of the disease. Here, we developed a novel rat hindlimb model of secondary lymphedema and showed that our rat model mimics human secondary lymphedema from early to late stages in terms of cell proliferation, lymphatic fluid accumulation, and skin fibrosis. Using our animal model, we investigated the disease progression and found that transforming growth factor-beta 1 (TGFB1) was produced by macrophages in the acute phase and by fibroblasts in the chronic phase of the disease. TGFB1 promoted the transition of fibroblasts into myofibroblasts and accelerated collagen synthesis, resulting in fibrosis, which further indicates that myofibroblasts and TGFB1/Smad signaling play key roles in fibrotic diseases. Furthermore, the presence of myofibroblasts in skin samples from lymphedema patients after cancer surgery emphasizes the role of these cells in promoting fibrosis. Suppression of myofibroblast-dependent TGFB1 production may therefore represent an effective pharmacological treatment for inhibiting skin fibrosis in human secondary lymphedema after cancer surgery.

Development of a Noninvasive Skin Evaluation Method for Lower Limb Lymphedema.

Background: The skin's condition is altered in lymphedema patients, and evaluating this change is important. Some noninvasive methods for evaluating skin condition have been reported, especially in upper limb lymphedema. However, evaluating the skin in lower limb lymphedema remains challenging and is often limited to palpation. We aimed to develop a noninvasive skin evaluation method for lower limb lymphedema patients. Methods and Results: Twenty-five lower limb lymphedema patients were included. Skin induration and elasticity were measured using Indentometer® IDM 400 and Cutometer® MPA580. The relationship between the properties of skin from the healthy forearm and thigh, those of the affected thigh, and age was analyzed. Predicted skin induration age (IA) and elasticity age (EA) were calculated from the forearm, whereas actual values were calculated from the thigh, and the differences (ΔIA and ΔEA) were assessed. Patients were classified according to the International Society of Lymphology clinical staging system, and the differences in ΔIA and ΔEA were analyzed among the three groups (healthy, stage I/IIa, and stage IIb/III). Skin biopsy was performed in five unilateral lower limb lymphedema patients, and the dermal elastic fiber area was determined using microscopy with Elastica van Gieson staining. ΔEA significantly increased with disease progression, but ΔIA did not change significantly. Microscopy revealed elastic fiber filamentous changes, with decreased elastic fiber areas in lymphedema-affected skin. Conclusion: To our knowledge, this is the first report to evaluate lower limb skin elasticity in lymphedema quantitatively and noninvasively. ΔEA is useful for evaluating skin condition progression in lymphedema patients.

The Role of Animal Models in Elucidating the Etiology and Pathology of Abdominal Aortic Aneurysms: Development of a Novel Rupture Mechanism Model.

Existing animal models do not replicate all aspects of abdominal aortic aneurysms (AAAs), including the rupture mechanisms. From histopathological analyses conducted in humans, it has been found that the vasa vasorum of the AAA wall is the starting point of circulatory failure and that bulging and dilatation of the abdominal aorta occurs through inflammation and tissue degeneration. We created a new animal model (the hypoperfusion-induced model) of AAAs. In this study, we describe the current animal models of AAAs and present the utility of our new model of AAAs.

Flow dynamics of type II endoleaks can determine sac expansion after endovascular aneurysm repair using four-dimensional flow-sensitive magnetic resonance imaging analysis.

OBJECTIVE: The objective of this study was to investigate the hemodynamic parameters of type II endoleaks (T2ELs) to predict sac expansion using four-dimensional flow-sensitive magnetic resonance imaging (4D-flow MRI) analysis. METHODS: Patients who underwent endovascular aneurysm repair (EVAR) and were diagnosed with a T2EL were included in the study. Using 4D-flow MRI at 7 days, the peak flow velocity and amplitude of dynamics of blood flow per minute were measured in each T2EL vessel. The peak flow velocity was defined as the maximum of the absolute value of the blood flow velocity. The amplitude of dynamics of blood flow in the tributary arteries was defined as the sum of the absolute values of the inflow and outflow volume in each vessel. The amplitude of dynamics of blood flow in the tributary arteries per sac was calculated in each sac. The aneurysm sac diameter was measured by computed tomography (CT) at 1 year. The patients were divided into two groups according to the presence or absence of sac expansion. RESULTS: Of 155 patients who underwent EVAR, both CT angiography and 4D-flow MRI were performed in 107 patients at 7 days after EVAR. Among them, 39 (36.4%) were found to have a T2EL, of whom 28 were re-evaluated with CT angiography and 4D-flow at 1 year; 7 patients had expanding sacs (expanding group), whereas 21 had nonexpanding sacs (not-expanding group). At 7 days, 28 patients had 80 T2EL vessels detected by 4D-flow MRI, of which 39 vessels (48.8%) had stopped flowing at 1 year (transient vessels); 41 vessels (51.3%) had sustained flow (persistent vessels). The persistent vessels had significantly larger peak flow velocity and amplitude of dynamics of blood flow. The comprehensive analysis of T2EL vessels per sac identified that the amplitude of dynamics of blood flow in the tributary arteries per sac was significantly higher in the expanding group than in the not-expanding group. A receiver operating characteristic curve analysis revealed that the sensitivity and specificity of sac enlargement at a cutoff value of 3750 mm3/min were 85.7% and 76.2%, respectively. CONCLUSIONS: The fate of aneurysm sacs with T2ELs after EVAR has remained difficult to predict. A comprehensive analysis of concurrent multiple T2EL vessels using 4D-flow MRI analysis may enable prediction of the sac expansion after EVAR.

Axillo-Axillary Artery Bypass With Coil Embolization of the Innominate Artery for a Traumatic Innominate Artery Aneurysm: A Case Report.

BACKGROUND: Innominate artery aneurysm (IAA) is a rare cervical artery aneurysm. Although atherosclerosis is its most common cause, IAAs due to cervical injury are often reported. Operative indications for IAAs include rupture or symptomatic aneurysm, saccular aneurysm, aneurysm with a diameter of 3 cm or greater, and aneurysmal change of the origin of the innominate artery. Although the ligature of the innominate artery or open surgical repair is well described, the usefulness of endovascular repair has also recently been reported. Herein, we report a case of traumatic IAA with infection in the cervical region after tracheostomy. CASE PRESENTATION: A 40-year-old man with cholecystolithiasis planned to undergo laparoscopic cholecystectomy at another hospital. Urgent tracheostomy was performed because of laryngeal edema at the induction of general anesthesia. Enhanced computed tomography angiography 1 week after the tracheostomy revealed a saccular IAA. The patient was deemed to be at high risk for aneurysm rupture and was referred to our hospital. Preoperative Matas test, Allcock test, and innominate arterial stump pressure measurement were performed to assess the cerebral blood flow and ischemic tolerance of the brain. These examinations showed the patency of the circle of Willis. An axillo-axillary artery bypass with coil embolization of the innominate artery was performed to avoid postoperative vascular graft infection. No postoperative complications such as infection or cerebral infarction occurred. Magnetic resonance imaging angiography performed 6 months after surgical treatment showed that the aneurysm had disappeared, and patency of the bypass graft was present. There were no postoperative complications, such as neurological deficits or graft infection, at more than 5 years after surgery. CONCLUSIONS: We report a successfully treated case of IAA after tracheostomy. Axillo-axillary artery bypass with coil embolization of the innominate artery is an effective treatment of IAA with cervical infection.

Characteristic Distribution Pattern of Lysophosphatidylcholine in Fibromuscular Dysplasia-Associated Visceral Artery Aneurysms Compared with Atherosclerotic Visceral Artery Aneurysms.

AIM: Asymptomatic visceral artery aneurysms (VAAs) have increasingly been found, with most being either atherosclerotic VAAs or fibromuscular dysplasia (FMD)-associated VAAs. However, little is known about the pathogenesis of both diseases. We aimed to identify the differences in the distribution pattern of lipid molecules between atherosclerotic VAAs and FMD-associated VAAs. METHODS: We conducted a histological study of VAAs using imaging mass spectrometry (IMS) to assess the accumulation of lipid molecules in both the aneurysmal sac and the adjacent arteries without aneurysmal changes in 17 VAA samples, which were resected during the surgery. RESULTS: IMS revealed characteristic distributions of cholesterol ester in intima and media in the atherosclerotic VAAs, which was hardly detected in FMD-associated VAAs. However, lysophosphatidylcholine (lysoPC), a proinflammatory and proapoptotic lipid mediator, was accumulated in the medial ridge of the adventitia of FMD-associated in the aneurysmal sac, and it was also diffusely accumulated in the adjacent arteries. In contrast, lysoPC was accumulated in the area of intimal hyperplasia in atherosclerotic VAAs and the adjacent arteries. CONCLUSION: The distribution patterns of lipid molecules were different between the FMD-associated and atherosclerotic VAAs. The diffuse accumulation of lysoPCs in the visceral arteries may be a predisposition for the formation of FMD-associated VAAs.

Imaging Mass Spectrometry Reveals a Unique Distribution of Triglycerides in the Abdominal Aortic Aneurysmal Wall.

The pathophysiology underlying abdominal aortic aneurysms (AAAs) remains unknown. In this study, we applied imaging mass spectrometry (IMS) to analyze the pathophysiology of the aneurysmal wall. Comparisons were performed between the tissue samples from the neck and the sac of the AAA, at a single time point, in 30 patients who underwent elective surgery of their AAAs. The localization of each lipid molecule in the aortic wall was assessed by IMS. Histopathological examination and IMS revealed a characteristic distribution of triglycerides (TGs) specifically in the aneurismal adventitia of the sac. This characteristic TG distribution was derived from an ectopic appearance of adipocytes in the adventitia. Furthermore, ectopic adipocyte accumulation in the aortic wall leads to the loss of the collagen fiber network subsequent to the wall rupture. The underlying mechanism of adipocyte accumulation involves the presence of adipose-derived stem cells (ADSCs) in the aneurismal adventitia and the expression of peroxisome proliferator-activated receptor gamma 2, a master regulator of adipocyte differentiation by some ADSCs. This study reveals new, previously overlooked aspects of AAA pathology.