In-stent Restenosis After Stenting for Superior Mesenteric Artery Dissection Is Associated With Stent Landing Zone: From Clinical Prediction to Hemodynamic Mechanisms.

OBJECTIVE: To identify risk factors for in-stent restenosis (ISR) in patients undergoing stent placement for superior mesenteric artery dissection (SMAD) and to determine the hemodynamic mechanism underlying ISR. METHODS: For this retrospective study, patients with SMAD who had ISR after stent placement were included in the ISR group, and age- and sex-matched patients with SMAD who did not experience ISR after stent placement were included in the control group. Clinical, imaging, and hemodynamic data were assessed. Multivariable regression was used to identify independent ISR risk factors. Structural and fluid dynamics simulations were applied to determine the hemodynamic mechanism underlying the occurrence of ISR. RESULTS: The study population included 26 patients with ISR and 26 control patients. Multivariate analysis demonstrated that stent-to-vascular (S/V) ratio (odds ratio [OR], 1.14; 95% confidence interval [CI]: 1.00-1.29; p=0.045), stent proximal position >10 mm away from the SMA root (OR, 108.67; 95% CI: 3.09-3816.42; p=0.010), and high oscillatory shear index (OSI) area (OR, 1.25; 95% CI: 1.02-1.52; p=0.029) were predictors of ISR. In structural and fluid dynamics simulations, a stent proximal position near the abdominal aorta (AA) or entering into the AA reduced the contact area between the proximal struts of the stent and the vascular wall, and alleviated the distal lumen overdilation. CONCLUSION: The S/V ratio, stent proximal position away from the SMA root (>10 mm), and high OSI area are independent risk factors for ISR in patients with SMAD undergoing stent placement. Deploying the proximal end of the stent near the AA or entering into the AA appears to improve the hemodynamic environment in the SMA lumen and ultimately reduce the risk of ISR. CLINICAL IMPACT: In-stent restenosis is an uncommon but potentially catastrophic complication after stent placement for the management of superior mesenteric artery dissection. This study identified risk factors for in-stent restenosis and demonstrated that, as long as the stent can fully cover the dissection range, deploying the proximal end of the stent near the abdominal aorta or less entering into the abdominal aorta may reduce the risk of in-stent restenosis in this patient population.

Multimodal Study of the Superior Mesenteric Artery Wall.

BACKGROUND: To quantitatively analyze histological and fiber structure of the superior mesenteric artery (SMA) wall and to further explore the possible relationship between the architecture and histology changes of vessel wall and the occurrence of related diseases. METHODS: Histological and fiber structure analysis were performed on SMA specimens obtained from 22 cadavers. The SMA specimens were divided into initial, curved, and distal segments, and each segment was separated into the anterior and posterior walls. RESULTS: From the initial to the curved to the distal segment, the ratio of elastin decreased (31.4% ± 6.0%, 21.1% ± 5.8%, 18.6% ± 4.7%, respectively; P < 0.001), whereas the ratio of smooth muscle actin (24.5% ± 8.7%, 30.5% ± 6.8%, 36.1% ± 7.3%, respectively; P < 0.001) increased. Elastic fiber longitudinal amplitude of angular undulation was highest in the initial segment [7° (3.25°, 15°)] and lowest in the curved segment [2° (1°, 5°)]. In SMA curved segment, the anterior wall, when compared with the posterior wall, demonstrated a lower ratio of elastin (19.0% ± 5.8% vs. 23.3% ± 5.0%; P = 0.010) and collagen (41.4% ± 12.3% vs. 49.0% ± 10.2%; P = 0.032), a lower elastic fiber longitudinal amplitude of angular undulation [1° (1°, 5°) vs. 3° (2°, 5.25°); P = 0.013], a lower average fiber diameter (8.06 ± 0.36 pixels vs. 8.45 ± 0.50 pixels; P = 0.005), and a lower average segment length (17.96 ± 1.59 pixels vs. 20.05 ± 2.33 pixels; P = 0.001). CONCLUSIONS: SMA wall structure varies along the circumferential and axial directions, the presence of dense undulated elastic fiber protects the SMA initial segment of from dissection and aneurysm, but highly cross-linked collagen fiber here increases the likelihood of plaque formation. In the anterior wall of the curved segment, lower elastin and collagen content, lower elastic fiber undulation, and higher degree of collagen fiber cross-linking leads to the occurrence of SMA dissection and aneurysm. In the distal segment, high levels of vascular smooth muscle cells and bundles of long collagen fiber offer protection against the development of SMA-related diseases.

Deep learning algorithm applied to plain CT images to identify superior mesenteric artery abnormalities.

OBJECTIVES: Atypical presentations, lack of biomarkers, and low sensitivity of plain CT can delay the diagnosis of superior mesenteric artery (SMA) abnormalities, resulting in poor clinical outcomes. Our study aims to develop a deep learning (DL) model for detecting SMA abnormalities in plain CT and evaluate its performance in comparison with a clinical model and radiologist assessment. MATERIALS AND METHODS: A total of 1048 patients comprised the internal (474 patients with SMA abnormalities, 474 controls) and external testing (50 patients with SMA abnormalities, 50 controls) cohorts. The internal cohort was divided into the training cohort (n = 776), validation cohort (n = 86), and internal testing cohort (n = 86). A total of 5 You Only Look Once version 8 (YOLOv8)-based DL submodels were developed, and the performance of the optimal submodel was compared with that of a clinical model and of experienced radiologists. RESULTS: Of the submodels, YOLOv8x had the best performance. The area under the curve (AUC) of the YOLOv8x submodel was higher than that of the clinical model (internal test set: 0.990 vs 0.878, P =.002; external test set: 0.967 vs 0.912, P =.140) and that of all radiologists (P <.001). The YOLOv8x submodel, when compared with radiologist assessment, demonstrated higher sensitivity (internal test set: 100.0 % vs 70.7 %, P =.002; external test set: 96.0 % vs 68.8 %, P <.001) and specificity (internal test set: 90.7 % vs 66.0 %, P =.025; external test set: = 88.0 % vs 66.0 %, P <.001). CONCLUSION: Using plain CT images, YOLOv8x was able to efficiently identify cases of SMA abnormalities. This could potentially improve early diagnosis accuracy and thus improve clinical outcomes.

Factors associated with false lumen changes in patients with superior mesenteric artery dissection.

BACKGROUND: False lumen changes (FLCs) are the main reference for the prognosis judgment and treatment plan selection for type IIa superior mesenteric artery dissection (SMAD). METHODS: For this retrospective study, 55 patients with symptomatic type IIa SMAD were included. Computational fluid dynamics (CFD) analysis was used to explore the hemodynamic basis of FLCs. Correlation and multiple linear regression analyses were performed to identify clinical, morphological and hemodynamic factors associated with FLCs. RESULTS: The FLCs of patients with successful conservative treatment (n = 29) are significantly higher than those with failed conservative treatment (n = 26) (58.5 ± 21.1% vs 10.9 ± 17.4%, p < 0.0001). Positive correlations were seen between FLCs and the morphological parameters false lumen length (FLL)/dissection entrance length (DEL) and FLL. In terms of hemodynamic parameters, negative correlations were seen between FLCs and time-averaged wall shear stress (TAWSS), vorticity, and high areas of TAWSS and vorticity, whereas positive correlations were seen between FLCs and oscillatory shear index (OSI), relative residence time (RRT), and high areas of OSI and RRT. Multiple linear regression analysis identified symptom duration (odds ratio [OR], 0.93; 95% CI, 0.91-0.96; p < 0.0001), FLL/DEL (OR, 1.30; 95% CI, 1.01-1.67; p = 0.044), and high RRT area (OR, 2.03; 95% CI, 1.48-2.78; p < 0.0001) as predictors of FLCs. CONCLUSION: The clinical predictor symptom duration, morphological factor FLL/DEL, and the hemodynamic factor high RRT area can serve as predictors of FLCs in patients with symptomatic type IIa SMAD.

Isolated superior mesenteric artery dissection: An updated review of the literature.

Isolated superior mesenteric artery dissection (ISMAD) is a rare but potentially life-threatening cause of acute abdominal pain. Owing to the availability of computed tomography angiography, more cases have been detected during screening for acute abdomen in recent years. With increasing knowledge of ISMAD, a better management strategy is being developed. To enhance our understanding and improve treatment outcomes of ISMAD, a systematic literature review was conducted with a focus on diagnosis and management strategies based on existing evidence.

Different hemodynamic factors cause the occurrence of superior mesenteric atherosclerotic stenosis and superior mesenteric artery dissection.

Objective: To compare the hemodynamic factors involved in the occurrence of superior mesenteric atherosclerotic stenosis (SMAS) and superior mesenteric artery (SMA) dissection (SMAD). Methods: Hospital records were searched to identify consecutive patients who were diagnosed with SMAS or SMAD between January 2015 and December 2021. A computational fluid dynamics (CFD) simulation method was used to assess the hemodynamic factors of the SMA in these patients. Histologic analysis was also performed on SMA specimens obtained from 10 cadavers, and scanning electron microscopy was used to evaluate collagen microstructure. Results: A total of 124 patients with SMAS and 61 patients with SMAD were included. Most SMASs were circumferentially distributed at the SMA root, whereas the origin of most SMADs was located on the anterior wall of the curved segment of the SMA. Vortex, higher turbulent kinetic energy (TKE), and lower wall shear stress (WSS) were observed near plaques; higher TKE and WSS were seen near dissection origins. The intima in the SMA root (388.5 ± 202.3 µm) was thicker than in the curved (243.8 ± 100.5 µm; p = .007) and distal (183.7 ± 88.0 µm; p < .001) segments. The media in the anterior wall (353.1 ± 37.6 µm) was thinner than that in the posterior wall (473.7 ± 142.8 µm; p = .02) in the curved segment of the SMA. The gaps in the lamellar structure in the SMA root were larger than in the curved and distal segments. The collagen microstructure was more substantially disturbed in the anterior wall than in the posterior wall in the curved segment of the SMA. Conclusion: Different hemodynamic factors in different portions of the SMA are related to local pathological changes in the SMA wall and may lead to the occurrence of SMAS or SMAD.

The pathogenesis of superior mesenteric artery dissection: An in-depth study based on fluid-structure interaction and histology analysis.

OBJECTIVE: To explore the role of hemodynamic factors in the occurrence of superior mesenteric artery (SMA) dissection (SMAD) using a fluid-structure interaction (FSI) simulation method, and to identify histopathologic changes occurring in the wall of the SMA. METHODS: A total of 122 consecutive patients diagnosed with SMAD and 122 controls were included in this study. Hemodynamic factors were calculated using a FSI simulation method. Additionally, SMA specimens obtained from 12 cadavers were stained for histological quantitative analysis. RESULTS: The mean aortomesenteric angle (59.7° ± 21.4° vs 48.2° ± 16.8°; p < .001) and SMA maximum curvature (0.084 ± 0.078 mm-1 vs 0.032 ± 0.023 mm-1; p < .001) were higher in SMAD patients than the controls. Larger aortomesenteric angles and SMA curvatures were associated with higher and more concentrated wall shear stress at anterior wall of the SMA curve segment, co-located with the dissection origins. The mean thickness of media (325.18 ± 44.87 µm vs 556.92 ± 138.32 µm; p = .003) was thinner in the anterior wall of the SMA curve than in the posterior wall. The area fractions of elastin (17.96% ± 3.36% vs 27.06% ± 4.18%; p = .002) and collagen (45.43% ± 6.89% vs 55.57% ± 7.57%; p = .036) were lower in anterior wall of the SMA curve than in posterior wall. CONCLUSION: Increased aortomesenteric angle and SMA curvature are risk factors for SMAD. Both of these factors can cause local hemodynamic abnormalities, which can lead to histopathologic changes in anterior wall of SMA.

Angiography findings and endovascular management of acute nonvariceal gastrointestinal bleeding: A pictorial essay.

Patients with acute nonvariceal gastrointestinal bleeding (GIB) not treatable via endoscopic therapy require angiography and endovascular management. If the source of the bleeding can be identified on angiography, the bleeding can be controlled with minimal complications by endovascular treatments such as intra-arterial infusion of vasopressin, embolization, covered stent placement, or a combination thereof. This pictorial essay reviews the angiographic findings for and the endovascular management of acute nonvariceal GIB.

The efficacy of a paeoniflorin-sodium alginate-gelatin skin scaffold for the treatment of diabetic wound: An in vivo study in a rat model.

OBJECTIVE: To investigate the efficacy of a paeoniflorin-sodium alginate (SA)-gelatin skin scaffold for treating diabetic wound in a rat model. METHODS: Bioinks were prepared using various percentages of paeoniflorin in the total weight of a solution containing SA and gelatin. Skin scaffolds containing 0%, 1%, 3%, 5%, and 10% paeoniflorin were printed using 3D bioprinting technology, and scaffold microstructure was observed with scanning electron microscopy. Skin scaffolds were then used in rats with diabetic wounds. H&E staining, Masson staining, and immunohistochemical staining for IL-1ß and CD31 were performed on days 7 and 14. RESULTS: All skin scaffolds had a mesh-like structure with uniform pore distribution. Wounds healed well in each group, with the 1% and 3% groups demonstrating the most complete healing. H&E staining showed that skin accessory organs had appeared in each group. On day 7, collagen deposition in the 3% group was higher than in the other groups (P＜0.05), and IL-1ß infiltration was lower in the 10% group than in the 3% group (P = 0.002). On day 14, IL-1ß infiltration was not significantly different between the 10% and 3% groups (P = 0.078). The CD31 level was higher in the 3% group than in the other groups on days 7 and 14 (P＜0.05). CONCLUSION: A 3% paeoniflorin-SA-gelatin skin scaffold promoted the healing of diabetic wounds in rats. This scaffold promoted collagen deposition and microvascular regeneration and demonstrated anti-inflammatory properties, suggesting that this scaffold type could be used to treat diabetic wounds.

Seed Pelleting with Calcium Peroxide Improves Crop Establishment of Direct-seeded Rice under Waterlogging Conditions.

Poor crop establishment of direct-seeded rice (DSR) is one of the major constraints to wide adoption of DSR, particularly in areas prone to flooding after sowing or where fields are not level. Seed pelleting is an effective, practical and facile technique to enhance crop establishment under unfavorable environmental conditions. To evaluate the effects of seed pelleting on rice germination, seedling growth and associated metabolic events under waterlogging stress, various seed pelleting treatments including formulae, pelleting times (the weight ratio of pelleting agents: rice seeds = 1:1~7:1 (w/w) and CaO2 contents were tested in series of experiments. Naked seeds were maintained for comparison as a control. Pelleting treatments with CaO2 significantly increased seed germination and seedling growth of DSR under waterlogging conditions compared with pelleted seeds without CaO2 and naked seeds. The optimum weight ratios of CaO2 to dry seeds were found to be in the range of 0.6:1-1:1 based on seed germination and seedling growth performance under waterlogging conditions. Under waterlogging conditions, high seed germination percentage and vigorous seedling growth of DSR due to seed pelleting with CaO2 was associated with an increase in α-amylase activity, but decrease in alcohol dehydrogenase (ADH) and pyruvate decarboxylase (PDC) activities in pelleted seeds.

Effects of pre-sowing seed treatments on establishment of dry direct-seeded early rice under chilling stress.

Mechanization and simplification are inevitable trends in agriculture production to decrease input demands and simultaneously improve resource use efficiency. Dry direct-seeded rice is a resource-saving cropping system and has been considered as a replacement for traditional transplanted rice. However, the poor establishment of dry direct-seeded early rice, primarily induced by chilling stress, has limited the wide adoption of this system. To examine the effects of pre-sowing seed treatments on rice germination, seedling growth and associated metabolic events under chilling stress, two seed coating treatments (Hanyubaomu coating and Miaoboshi coating) and two seed priming treatments (selenium priming and salicylic acid priming) were tested in field and growth chamber experiments. The results revealed that under chilling stress, seed priming increased the rice seed germination by 20.96-26.31 %. The length and weight of shoots and roots were also significantly increased. The two seed coating treatments were not effective in enhancing seed germination and seedling growth under chilling stress. The improved germination and seedling growth of primed seeds under chilling stress were strongly linked with higher α-amylase activity and total soluble sugar content. Conclusively, these findings will provide new avenues for understanding and advancing pre-sowing seed treatments of dry direct-seeded early rice.

Pre-sowing Seed Treatments in Direct-seeded Early Rice: Consequences for Emergence, Seedling Growth and Associated Metabolic Events under Chilling Stress.

Double direct-seeding for double rice cropping is a simplified, labor saving, and efficient cropping system to improve multiple-crop index and total rice production in central China. However, poor crop establishment of direct-seeded early rice due to chilling stress is the main obstacle to wide spread of this system. A series of experiments were conducted to unravel the effects of pre-sowing seed treatments on emergence, seedling growth and associated metabolic events of direct-seeded early rice under chilling stress. Two seed priming treatments and two seed coating treatments were used in all the experiments. A non-treated control treatment was also maintained for comparison. In both the field and growth chamber studies, seed priming with selenium or salicylic acid significantly enhanced the emergence and seedling growth of rice compared with non-treated control. Nevertheless, such positive effects were not apparent for seed coating treatments. Better emergence and vigorous seedling growth of rice after seed priming was associated with enhanced α-amylase activity, higher soluble sugars contents, and greater respiration rate in primed rice seedlings under chilling stress. Taking together, these findings may provide new avenues for understanding and advancing priming-induced chilling tolerance in direct-seeded early rice in double rice cropping system.