Field- and Temperature-Dependent Paramagnetic Relaxation Enhancements in Co(II) Trispyrazolylmethanes.

A comprehensive field- and temperature-dependent examination of nuclear magnetic resonance paramagnetic relaxation enhancements (PREs) for the constitutive protons of [Co(Tpm)2][BF4]2 is presented. Data for an apically substituted derivative clearly establish that bis-Tpm complexes of Co(II) undergo Jahn-Teller dynamics about the molecular threefold axis. PREs from the parent Tpm complex were used to numerically extract the electron relaxation times (T1e). The Tpm complex showed field-dependent behavior, with an approximately 40% higher activation barrier than the related trispyrazolylborate (Tp) complex, based on fits to the T1e vs T, B0 data. Analysis of the field-dependent line widths revealed a surprisingly large contribution from susceptibility (Curie) relaxation (20-35% at the highest field), and a molecular radius (9.5 Å) that is consistent with a tightly associated counterion slowing rotation in solution. Density functional theory showed a shared vibration that is consistent with the Jahn-Teller and appears proportionately higher in energy in [Co(Tpm)2]2+. Complete active-space self-consistent field calculations support ascribing electron relaxation to enhanced mixing of the two Eg orbital sets that accompanies the tetragonal distortion and the differences in electron correlation times to the higher Jahn-Teller activation barrier in [Co(Tpm)2]2+.

Mechanochemically accessing a challenging-to-synthesize depolymerizable polymer.

Polymers with low ceiling temperatures (Tc) are highly desirable as they can depolymerize under mild conditions, but they typically suffer from demanding synthetic conditions and poor stability. We envision that this challenge can be addressed by developing high-Tc polymers that can be converted into low-Tc polymers on demand. Here, we demonstrate the mechanochemical generation of a low-Tc polymer, poly(2,5-dihydrofuran) (PDHF), from an unsaturated polyether that contains cyclobutane-fused THF in each repeat unit. Upon mechanically induced cycloreversion of cyclobutane, each repeat unit generates three repeat units of PDHF. The resulting PDHF completely depolymerizes into 2,5-dihydrofuran in the presence of a ruthenium catalyst. The mechanochemical generation of the otherwise difficult-to-synthesize PDHF highlights the power of polymer mechanochemistry in accessing elusive structures. The concept of mechanochemically regulating the Tc of polymers can be applied to develop next-generation sustainable plastics.

Achiral Nanoparticle-Enhanced Chiral Twist and Thermal Stability of Blue Phase Liquid Crystals.

Blue phase liquid crystals (BPLCs) are chiral mesophases with 3D order, which makes them a promising template for doping nanoparticles (NPs), yielding tunable nanomaterials attractive for microlasers and numerous microsensor applications. However, doping NPs to BPLCs causes BP lattice extension, which translates to elongation of operating wavelengths of light reflection. Here, it is demonstrated that small (2.4 nm diameter) achiral gold (Au) NPs decorated with designed LC-like ligands can enhance the chiral twist of BPLCs (i.e., reduce cell size of the single BP unit up to ∼14% and ∼7% for BPI and BPII, respectively), translating to a blue-shift of Bragg reflection. Doping NPs also significantly increases the thermal stability of BPs from 5.5 °C (for undoped BPLC) up to 22.8 °C (for doped BPLC). In line with our expectations, both effects are saturated, and their magnitude depends on the concentration of investigated nanodopants as well the BP phase type. Our research highlights the critical role of functionalization of Au NPs on the phase sequence of BPLCs. We show that inappropriate selection of surface ligands can destabilize BPs. Our BPLC and Au NPs are photochemically stable and exhibit great miscibility, preventing NP aggregation in the BPLC matrix over the long term. We believe that our findings will improve the fabrication of advanced nanomaterials into 3D periodic soft photonic structures.

Uncertainty measurement of radiomics features against inherent quantum noise in computed tomography imaging.

OBJECTIVES: Quantum noise is a random process in X-ray-based imaging systems. We addressed and measured the uncertainty of radiomics features against this quantum noise in computed tomography (CT) images. METHODS: A clinical multi-detector CT scanner, two homogeneous phantom sets, and four heterogeneous samples were used. A solid tumor tissue removed from a male BALB/c mouse was included. We the placed phantom sets on the CT scanning table and repeated 20 acquisitions with identical imaging settings. Regions of interest were delineated for feature extraction. Statistical quantities-average, standard deviation, and percentage uncertainty-were calculated from these 20 repeated scans. Percentage uncertainty was used to measure and quantify feature stability against quantum noise. Twelve radiomics features were measured. Random noise was added to study the robustness of machine learning classifiers against feature uncertainty. RESULTS: We found the ranges of percentage uncertainties from homogeneous soft tissue phantoms, homogeneous bone phantoms, and solid tumor tissue to be 0.01-2138%, 0.02-15%, and 0.18-16%, respectively. Overall, it was found that the CT features ShortRunHighGrayLevelEmpha (SRHGE) (0.01-0.18%), ShortRunLowGrayLevelEmpha (SRLGE) (0.01-0.41%), LowGrayLevelRunEmpha (LGRE) (0.01-0.39%), and LongRunLowGrayLevelEmpha (LRLGE) (0.02-0.66%) were the most stable features against the inherent quantum noise. The most unstable features were cluster shade (1-2138%) and max probability (1-16%). The impact of random noise to the prediction accuracy by different machine learning classifiers was found to be between 0 and 12%. CONCLUSIONS: Twelve features were used for uncertainty measurements. The upper and lower bounds of percentage uncertainties were determined. The quantum noise effect on machine learning classifiers is model dependent. KEY POINTS: • Quantum noise is a random process and is intrinsic to X-ray-based imaging systems. This inherent quantum noise creates unpredictable fluctuations in the gray-level intensities of image pixels. Extra cautions and further validations are strongly recommended when unstable radiomics features are selected by a predictive model for disease classification or treatment outcome prognosis. • We addressed and used the statistical quantity of percentage uncertainty to measure the uncertainty of radiomics features against the inherent quantum noise in computed tomography (CT) images. • A clinical multi-detector CT scanner, two homogeneous phantom sets, and four heterogeneous samples were used in the stability measurement. A solid tumor tissue removed from a male BALB/c mouse was included in the heterogeneous sample.

Stochastic determination of the spatial variation of potentially pathogenic bacteria communities in a large subtropical river.

Understanding the composition and assembly mechanism of waterborne pathogen is essential for preventing the pathogenic infection and protecting the human health. Here, based on 16S rRNA sequencing, we investigated the composition and spatial variation of potentially pathogenic bacteria from different sections of the Pearl River, the most important source of water for human in Southern China. The results showed that the potential pathogen communities consisted of 6 phyla and 64 genera, covering 11 categories of potential pathogens mainly involving animal parasites or symbionts (AniP), human pathogens all (HumPA), and intracellular parasites (IntCelP). Proteobacteria (75.87%) and Chlamydiae (20.56%) were dominant at the phylum level, and Acinetobacter (35.01%) and Roseomonas (8.24%) were dominant at the genus level. Multivariate analysis showed that the potential pathogenic bacterial community was significantly different among the four sections in the Pearl River. Both physicochemical factors (e.g., NO3-N, and suspended solids) and land use (e.g., urban land and forest) significantly shaped the pathogen community structure. However, spatial effects contributed more to the variation of pathogen community based on variation partitioning and path analysis. Null model based normalized stochasticity ratio analysis further indicated that the stochastic process rather than deterministic process dominated the assembly mechanisms by controlling the spatial patterns of potential pathogens. In conclusion, high-throughput sequencing shows great potential for monitoring the potential pathogens, and provided more comprehensive information on the potentially pathogenic community. Our study highlighted the importance of considering the influences of dispersal-related processes in future risk assessments for the prevention and control of pathogenic bacteria.

Detection of membrane protein-protein interaction in planta based on dual-intein-coupled tripartite split-GFP association.

Despite the great interest in identifying protein-protein interactions (PPIs) in biological systems, only a few attempts have been made at large-scale PPI screening in planta. Unlike biochemical assays, bimolecular fluorescence complementation allows visualization of transient and weak PPIs in vivo at subcellular resolution. However, when the non-fluorescent fragments are highly expressed, spontaneous and irreversible self-assembly of the split halves can easily generate false positives. The recently developed tripartite split-GFP system was shown to be a reliable PPI reporter in mammalian and yeast cells. In this study, we adapted this methodology, in combination with the ß-estradiol-inducible expression cassette, for the detection of membrane PPIs in planta. Using a transient expression assay by agroinfiltration of Nicotiana benthamiana leaves, we demonstrate the utility of the tripartite split-GFP association in plant cells and affirm that the tripartite split-GFP system yields no spurious background signal even with abundant fusion proteins readily accessible to the compartments of interaction. By validating a few of the Arabidopsis PPIs, including the membrane PPIs implicated in phosphate homeostasis, we proved the fidelity of this assay for detection of PPIs in various cellular compartments in planta. Moreover, the technique combining the tripartite split-GFP association and dual-intein-mediated cleavage of polyprotein precursor is feasible in stably transformed Arabidopsis plants. Our results provide a proof-of-concept implementation of the tripartite split-GFP system as a potential tool for membrane PPI screens in planta.

Factors Affecting Optimal Aortic Remodeling After Thoracic Endovascular Aortic Repair of Type B (IIIb) Aortic Dissection.

PURPOSE: The purpose of this study was to determine factors associated with entire aortic remodeling after thoracic endovascular aortic repair (TEVAR) in patients with type B dissection. MATERIALS AND METHODS: The patients with type B (IIIb) dissections who underwent TEVAR from 2006 to 2013 with minimum of 2 years of follow-up computed tomography data were retrospectively reviewed. Based on the status of false lumen remodeling of entire aorta, patients were divided into three groups: complete regression, total thrombosis, and inadequate regression with patent abdominal false lumen. RESULTS: A total of 90 patients (72 males, 18 females; mean age 56.6 ± 16.4 years) were included and divided into the complete regression (n = 22), total thrombosis (n = 18), and inadequate regression (n = 50) groups. Multivariate logistic regression analysis indicated that dissection extension to iliac arteries, increased preoperative number of dissection tear over abdominal aorta, and decreased preoperative abdominal aorta bifurcation true lumen ratio, as compared between the inadequate and complete regression groups, were associated with a persistent false lumen (odds ratio = 33.33, 2.304, and 0.021; all, p ≤ 0.012). Comparison of 6, 12, and 24 months postoperative data revealed no significant differences at any level, suggesting that the true lumen area ratio might not change after 6 months postoperatively. CONCLUSIONS: Increased preoperative numbers of dissection tear around the abdominal visceral branches, dissection extension to the iliac arteries, and decreased preoperative true lumen area ratio of abdominal aorta are predictive of entire aortic remodeling after TEVAR in patients with type B dissection. LEVEL OF EVIDENCE: III.

Diagnostic Performance on Low Dose Computed Tomography For Acute Appendicitis Among Attending and Resident Radiologists.

BACKGROUND: Low-dose computed tomography (LDCT) techniques can reduce exposure to radiation. Several previous studies have shown that radiation dose reduction in LDCT does not decrease the diagnostic performance for appendicitis among attending radiologists. But, the LDCT diagnostic performance for acute appendicitis in radiology residents with variable training levels has not been well discussed. OBJECTIVES: To compare inter-observer and intra-observer differences of diagnostic performance on non-enhanced LDCT (NE-LDCT) and contrast-enhanced standard dose CT (CE-SDCT) for acute appendicitis among attending and resident radiologists. PATIENTS AND METHODS: This retrospective study included 101 patients with suspected acute appendicitis who underwent NE-LDCT and CE-SDCT. The CT examinations were interpreted and recorded on a five-point scale independently by three attending radiologists and three residents with 4, 1 and 1 years of training. Diagnostic performance for acute appendicitis of all readers on both examinations was represented by area under receiver operating characteristic (ROC) curves. Inter-observer and intra-observer AUC values were compared using Jackknife FROC software on both modalities. The diagnostic accuracy of each reader on NE-LDCT was compared with body mass index (BMI) subgroups and noise using independent T test. RESULTS: Diagnostic performances for acute appendicitis were not statistically different for attending radiologists at both examinations. Better performance was noted on the CE-SDCT with a borderline significant difference (P = 0.05) for senior radiology resident. No statistical difference of AUC values was observed between attending radiologists and fourth year resident on both examinations. Statistically significant differences of AUC values were observed between attending radiologists and first year residents (P = 0.001 ~ 0.018) on NE-LDCT. Diagnostic accuracies of acute appendicitis on NE-LDCT for each reader were not significantly related to BMI or noise. CONCLUSION: Attending radiologists could diagnose acute appendicitis accurately on NE-LDCT. Performance of senior residents on NE-LDCT is better than junior residents and comparable to attending radiologists.

Implantation sequence modification averts distal stent graft-induced new entry after endovascular repair of Stanford type B aortic dissection.

OBJECTIVE: This study investigated predisposing factors of distal stent graft-induced new entry (SINE). METHODS: Data from November 2006 to May 2012 were abstracted retrospectively from the records of 73 patients with complicated type B aortic dissection who had received stent graft treatment in our institution. Diameters of the true and false lumen, area and circumference of the true lumen, prestent and poststent oversize, taper, and mismatch ratio were recorded and analyzed to see if there were any significant differences between the SINE (n = 19) and non-SINE (n = 54) population and between those in whom the initial endograft was inserted from the proximal thoracic aorta (n = 49) or the distal thoracic aorta (n = 24). RESULTS: A distal-first sequence of stent graft deployment produced significantly fewer instances of distal SINE. The area oversizing ratio of the distal end of the stent graft was greater in the SINE vs non-SINE groups (3.76 ± 1.7 vs 2.63 ± 2.57; P = .002) and in the proximal-first vs distal-first deployment sequence groups (3.67 ± 2.57 vs 1.39 ± 0.90; P < .001). CONCLUSIONS: Minimizing the preprocedure distal oversizing ratio with a distal small graft-first procedure could reduce the risk of late distal SINE for Stanford type B aortic dissection. Furthermore, the area ratio is a potentially more sensitive modality for size assessment and prediction of distal SINE occurrence.

Association between Aortic Remodeling and Stent Graft-Induced New Entry in Extensive Residual Type A Dissecting Aortic Aneurysm after Hybrid Arch Repair.

BACKGROUND: This study evaluated sequential aortic morphologic remodeling and influencing factors between distal stent graft-induced new entry (SINE) in chronic residual type A dissecting aortic aneurysm after extensive hybrid arch repair. METHODS: We retrospectively analyzed operative and follow-up data of 30 consecutive patients with chronic residual type A aortic dissection aneurysm treated by hybrid type III arch repair (ascending aortic and arch replacement combined with elephant trunk technique before stent-graft deployment) between November 2006 and October 2011. RESULTS: In 3 years, follow-up of 24 patients with successful 1-stage hybrid arch repair and stent grafting. The ratio of true lumen area increased at pulmonary artery level, but minimal change was seen in the thoracic segment distal to stent graft and abdominal aorta. Late distal SINE occurred in 14 patients (SINE group). Cross-sectional area showed significant differences in distal end of pre-stenting graft oversizing ratio (SINE group 4.32 vs. non-SINE group 2.23, P = 0.021(∗)). The thoracic segment thrombosis rate was 90% in SINE and 57% in non-SINE (P = 0.089) groups. CONCLUSIONS: In homogenous population of chronic residual type A dissection, noticeable false lumen thrombosis with true lumen progressive dilatation was only found at the proximal descending aortic segment extending to the middle of stent grafts in both groups. A smaller size selection of the distal stent graft by area measurement would be accompanied with poor aortic remodeling but might be beneficial for SINE prevention. On the other hand, a larger size selection of the distal stent graft area might be favorable for aortic remodeling but could potentially induce SINE.

Nickel ions from a corroded cardiovascular stent induce monocytic cell apoptosis: Proposed impact on vascular remodeling and mechanism.

BACKGROUND/PURPOSE: Monocytes play important roles in inflammatory responses and vascular remodeling after vascular stenting. This research focused on impacts of nickel (Ni) ions released from a corroded cardiovascular stent on cytotoxicity and monocyte activation. METHODS: A human promonocytic (macrophage-like) cell line (U937) was exposed to graduated concentrations of Ni(2+)in vitro. Cells were observed and harvested at indicated times to determine the effects using histological and biochemical methods. RESULTS: Ni caused U937 cell death in dose- and time-dependent manners. In vitro, high concentrations of Ni(2+) (>240 µM) significantly induced cell apoptosis and increased terminal deoxynucleotidyl transferase (TdT) dUTP nick end labeling (TUNEL)-positive cells according to flow cytometric surveillance and triggered apoptotic cell death. Although no significant changes in Bcl-2 or Bax expressions were detected after 24 hours of Ni(2+) treatment, increasing cleavage of caspase-3 and -8 was present. Results showed that cleavage of caspase-8 was inhibited by the presence of the inhibitor, Z-IETD-FMK, and this suggested the presence of Ni(2+)-induced U937 cell death through a death receptor-mediated pathway. Simultaneously, when treated with a high concentration of Ni(2+) ions, expressions of the vascular remodeling factors, matrix metalloproteinases (MMP)-9 and -2, were activated in dose- and time-dependent manners. Secretion of the proliferative factor, monocyte chemoattractant protein (MCP)-1, significantly increased during the first 6 hours of incubation with 480 µM Ni(2+)-treated medium. CONCLUSION: Our results demonstrated that a high concentration of Ni ions causes apoptotic cell death of circulating monocytes. They may also play different roles in vascular remodeling during the corrosion process following implantation of Ni alloy-containing devices.

Impact on outcomes by measuring tortuosity with reporting standards for thoracic endovascular aortic repair.

OBJECTIVE: In this study, we assessed the association between the tortuosity of the thoracic aorta as measured by the reporting standards for thoracic endovascular aortic repair (TEVAR), described by the Society for Vascular Surgery, and midterm outcomes after TEVAR for atherosclerotic aneurysms. METHODS: We analyzed 77 consecutive patients who underwent TEVAR for atherosclerotic aneurysms from November 2006 through May 2013 in a single institution. The preoperative aortic tortuosity index (TI) was calculated by computed tomography aortography, and patients were divided into low-tortuosity (TI ≤ 1.29) and high-tortuosity (TI > 1.29) groups. The relationships between TI and the occurrence of endoleaks, complications, and survival were analyzed. RESULTS: The mean follow-up period was 29 ± 26 months. During this period, endoleaks occurred in 19 patients. Patients in the high-tortuosity group were at greater risk for endoleaks (odds ratio, 9.95; 95% confidence interval, 2.06-48.1; P = .004) and stroke (odds ratio, 13.2; 95% confidence interval, 1.03-169; P = .047) than those in the low-tortuosity group. The overall survival at 1, 3, and 5 years was 73%, 69%, and 63%, respectively, for the high-tortuosity group and 92%, 92%, and 86%, respectively, for the low tortuosity group. CONCLUSIONS: Our findings demonstrated that high tortuosity of the thoracic aorta is associated with higher rates of endoleaks and lower survival in patients undergoing TEVAR for atherosclerotic aneurysms. Patients with aneurysms in a highly tortuous aorta may therefore need greater attention in preoperative planning, perioperative procedures, and follow-up examinations.

Early endovascular experience for treatments of Takayasu's arteritis.

BACKGROUND: Takayasu's arteritis (TA) is a chronic inflammatory disease that involves the aorta and its major branches; however, only limited data are available on TA in Taiwan. This study presents the clinical features, angiographic findings, and response to treatment of patients with TA at a single institute in Taiwan. METHODS: A search of the hospital database for ICD9 code 446.7 (Takayasu's disease) between 1990 and 2010 was performed. Seven cases fulfilled the 1990 American College of Rheumatology diagnostic criteria for Takayasu's disease. Angiographic classification was made according to the guidelines of the 1994 International TA Conference in Tokyo. RESULTS: All of our cases were female, and the median age at diagnosis was 27.5 years (range 14-36 years). Four patients had an angiographic classification of type I (57.1%), two were classified as type V (28.6%), and one was classified as type III (14.3%). The most common symptoms/signs were dizziness and vascular bruits. Two patients underwent bypass surgery, four endovascular stenting, and one hybrid bypass with stenting. After a mean follow-up period of 50.3 ± 68.2 months (range 12.3-199.6 months), both the procedure success and survival rates were 100%. There were four restenosis cases (57.1%), one in the surgical bypass group without symptoms (33.3%), and three in the endovascular group (60%), five restenosis in 14 stents (35.7%). Also, these three patients received secondary endovascular procedure for percutaneous transluminal angioplasty or restenting. CONCLUSION: There have not been any case series reports about treatments of Takayasu's disease in Taiwan to date, based on a search of the PubMed/MEDLINE and Cochrane Library databases. Although endovascular treatment is becoming more prevalent, the restenosis rate is still high, and long-term follow-up and further strategy for restenosis management are the main challenges.

Concomitant Bentall operation plus aortic arch replacement surgery.

BACKGROUND: The Bentall operation is recommended for thoracic aortic dissection or aneurysm involving the aortic root. However, if the lesion extends to the aortic arch, concomitant Bentall operation plus aortic arch replacement (CoBAAR) surgery is required. CoBAAR is challenging because of its complex cardiopulmonary procedure, prolonged cardiopulmonary bypass time, and demanding operative techniques. Therefore, surgical mortality and morbidity rates for CoBAAR are very high. However, the Bentall operation performed as a single procedure may lead to reoperation if the residual aneurysm progresses. Therefore, CoBAAR as a one-stage surgery can lower the need for reoperation and possible further complications. METHODS: Nine patients received CoBAAR during January 2005 to May 2010. Six patients were diagnosed with Sanford type A aortic dissection and three with nondissecting ascending aortic and arch aneurysm. Four patients received a Bentall operation plus hemiarch replacement. The others received a Bentall operation plus total arch replacement along with elephant trunk because of extensive lesions. RESULTS: The in-hospital mortality was 11.1% (1 patient with total arch replacement). Morbidity included stroke (2 patients), spinal cord injury (1 patient), mechanical ventilation for more than 72 hours (5 patients), and temporary renal dialysis (3 patients). Eight patients survived. CONCLUSION: CoBAAR is a demanding operative technique requiring complex cardiopulmonary bypass. However, surgeons can perform this procedure on extensive ascending aortic dissection or aneurysm patients, achieving satisfactory results.

Factors predictive of distal stent graft-induced new entry after hybrid arch elephant trunk repair with stainless steel-based device in aortic dissection.

OBJECTIVES: Stent graft-induced new entry (SINE) has been increasingly observed after thoracic endovascular aortic repair of aortic dissection. We illustrate the possible mechanism by exploring predictive factors of late distal SINE after hybrid arch elephant trunk repair for aortic dissection. METHODS: From November 2006, to May 2011, 20 of 99 patients underwent hybrid arch repair using the elephant trunk graft as the proximal landing zone. After a mean follow-up period of 27.9 ± 12.0 months, 12 patients had late distal SINE events and the others were free of events. False lumen remodeling level was observed and maximal longitudinal diameter, average of longitudinal and transverse maximal diameter, circumference, and area of true lumen were analyzed for precise size selection of stent graft before and after the procedure. Taper ratio, true lumen:aorta ratio, prestent grafting oversizing ratio, poststent grafting oversizing ratio, and expansion mismatch ratio of distal true lumen were proposed and calculated for further evaluation of the mechanism of late distal SINE. RESULTS: Only the area oversizing ratio between true lumen and the distal selected stent graft at the presumed distal end of stent grafting was found as a significant predictive factor of SINE before procedure (4.00 ± 2.96 vs 1.98 ± 0.66 for SINE vs non-SINE, respectively; P = .031). The significant difference of the expansion mismatch ratio of true lumen between the 2 groups was found not only in the size measurement of mean diameter (1.48 ± 0.29 vs 1.22 ± 0.15; P = .039), but also in the area (2.39 ± 0.85 vs 1.58 ± 0.42; P = .031) and circumference (1.43 ± 0.27 vs 1.18 ± 0.14; P = .016) after stent grafting. CONCLUSIONS: We found that taper ratio is not an optimal criteria for stent graft size selection and distal oversizing calculated by true-lumen area is a significant factor causing delayed distal SINE. Use of the prestenting area oversizing ratio should be limited.

Reintervention for distal stent graft-induced new entry after endovascular repair with a stainless steel-based device in aortic dissection.

OBJECTIVE: Stent graft-induced new entry (SINE) has been increasingly observed after thoracic endovascular aortic repair (TEVAR) for aortic dissection. We investigated the mechanism of late distal SINE, prevention strategies, proper size selection of the stent graft, and implantation sequence. METHODS: From November 2006 to May 2011, 99 patients with aortic dissection underwent TEVAR with Zenith TX2 stent grafts (Cook, Bloomington, Ind) at our center. Among them, 27 distal SINEs were recognized. Eight of these patients with complicated distal SINE required intervention with new distal endografts, and all were enrolled for further analysis. RESULTS: Eight of the 27 patients with distal SINE underwent a secondary endograft procedure from February 2011 to July 2011. All were successfully treated without any complications or deaths. A high taper ratio (35%±11%) and excessive oversizing of the true lumen area at the distal stent level (293%±76%) were noted among these patients. CONCLUSIONS: The incidence of distal SINE seemed to be high; however, there were also low rates of death and complications after TEVAR for aortic dissection using stainless steel-based stent grafts. Complicated distal SINE can successfully be resolved by distal endograft implantation. Excessive oversizing of the distal stent graft, as measured by the true lumen area, may be a significant factor causing delayed distal SINE. Precise size selection is crucial for the distal end of the stent, especially for high taper ratio dissection pathology in which the implantation sequence of a distal small-sized stent graft first might be considered to prevent future distal SINE.

Aortic remodeling after endovascular repair with stainless steel-based stent graft in acute and chronic type B aortic dissection.

OBJECTIVE: This study analyzes the experience of a single center using hybrid stainless steel-based endovascular stent graft repair of acute complicated and chronic type B aortic dissection aneurysm, and assesses the proximal and distal aortic morphologic changes of the midterm results. METHODS: Between November 2006 and March 2011, 61 patients with type B aortic dissection underwent stainless steel-based stent graft repair and were divided into an acute complicated dissection group (AD; n = 33) and a chronic dissection aneurysm group (CD; n = 28). Serial computed tomography (CT) images were obtained to evaluate the changes of true and false lumen diameter at four levels during the postoperative period. RESULTS: The stent graft was successfully implanted in all patients (100%), with two surgical mortalities in the AD group and low perioperative morbidity (3.6%) of stroke and paraplegia. The cumulative survival rates of the two groups were similar (77.6% and 89.0%; P = .585) in a mean follow-up period of 24.1 ± 15.6 months. Complete thrombosis of the thoracic false lumen down to the diaphragm level was achieved in 80.6% of the patients in the AD group and 88.5% in the CD group without significant difference (P = .221), but the complete regression rate of the thoracic false lumen down to the diaphragm level showed a tendency of propitious remodeling in the AD group (54.8% vs 30.8%; P = .068). During follow-up, despite the proximal changes of stented true and adjacent false lumen diameter being significantly increased and decreased, respectively, in both acute and chronic settings (P < .05), they were less prominent at the distal aorta in the CD aneurysm group. Intimomedial erosion of the distal end of the stent graft occurred in both acute (n = 6; 18.9%) and chronic (n = 10; 35.7%; P = .121) dissection settings after mean follow-up of 14.0 ± 4.8 months in the AD group and 24.8 ± 5.9 months in the CD group. Three patients with chronic dissection developed either pseudoaneurysm or true lumen compromise by expanded false lumen thrombi and required re-endografting. CONCLUSIONS: Endovascular stainless steel-based stent graft implantation with vascular bypass to gain a sufficient proximal landing zone is feasible for type B aortic dissection and has low early and midterm mortality and morbidity in both the acute and chronic phases. Although early intervention might result in more favorable aortic remodeling with a higher possibility of complete regression and lower risk of late distal erosion, longer-term follow-up still necessitates continuous careful surveillance of the entire aorta, especially the distal condition.

Early outcome of endovascular repair for contained ruptured abdominal aortic aneurysm.

BACKGROUND: Endovascular aneurysm repair (EVAR) has become a well-established technique in the treatment of elective surgery for abdominal aortic aneurysms (AAAs) due to proven benefits in mortality, hospital stay and operation time compared to open repair. The aim of this study was to report our experience in establishing the treatment protocol for EVAR of contained ruptured abdominal aortic aneurysms (rAAAs) and to illustrate the real impact of endovascular rAAA repair on surgical strategy. METHODS: Eighteen patients underwent AAA between January 2008 and October 2009. Six of them were enrolled in our study. The inclusion criteria were contained rAAA and the same anatomic consideration as in elective EVAR cases. The implant material was the Zenith AAA modular bifurcated device. Computed tomography (CT) scan was obtained in all patients pre-operatively and used as a follow-up tool. RESULTS: The mean age was 81 years (range 79-87 years). The procedural time was 259 ± 146 minutes, the maximal diameter of aneurismal sac was 8.4 ± 1.8 cm, and the pre-operative hemoglobin was 9.0 ± 1.2 mg/dL. The mean intensive care unit (ICU) stay was 10.5 ± 15 days. There was no surgical or in-hospital mortality. Complications included abdominal compartment syndrome, renal failure, wound infection and pneumonia. The mean follow-up period was 22 (range 19-29) months, with satisfactory result. CONCLUSION: Endovascular repair of rAAAs is feasible, and short-term results are promising, especially for contained and hemodynamic subgroup patients. It is indicated for elder patients with severe underlying diseases. Good logistics and adequate training of physicians or staff in an elective setting are prerequisites for this type of treatment program.

Left ventricular aneurysm repair: a comparison of linear versus patch remodeling.

BACKGROUND: Surgical repair of left ventricular (LV) aneurysm has been performed for around 50 years. However, the most appropriate surgical approach remains undetermined. This study was undertaken to compare the efficacy of 2 established techniques, linear versus patch remodeling, for repair of dyskinetic LV aneurysms. METHODS: We retrospectively reviewed the records of 49 patients (mean age, 69.8 +/- 7.3 years) who had operation for postinfarction dyskinetic LV aneurysm between 1996 and 2006. Thirty-one patients underwent patch remodeling and 18 underwent linear repair. Short-term and mid-term outcomes, including complications, cardiac function and mortality, were assessed. RESULTS: Overall inhospital surgical mortality, major complications and early hemodynamics showed no significant differences between the 2 groups. During a mean follow-up of 44.0 +/- 34.4 months, 8 patients died, with 4 due to cardiac-related causes. Actuarial survival rates at 1, 5 and 10 years were 85.7%, 69.9% and 45.7%, respectively. Functional class improved from 2.51 +/- 0.59 to 1.66 +/- 0.54 among the mid-term survivors (p < 0.001), with no significant difference between the 2 groups. Multivariate analysis identified preoperative NYHA functional class >or= 3 as an independent risk factor for overall mortality (p = 0.008). Mid-term follow-up revealed that LV ejection fraction improved from 26.5 +/- 7.2% to 34.1 +/- 7.9% (p < 0.001) in the patch group, and from 26.3 +/- 9.0% to 32.0 +/- 9.2% in the linear group (p = 0.032). In contrast, right ventricular ejection fraction improved from 49.4 +/- 10.1% to 52.0 +/- 7.3% (p = 0.190) in the patch group, but deteriorated from 55.0 +/- 6.3% to 50.3 +/- 8.6% in the linear group (p = 0.029). CONCLUSION: These findings indicate that the 2 repair techniques have similar effectiveness with respect to short- and mid-term outcomes except for right ventricular ejection fraction. We suggest that the selection of repair technique for LV aneurysms should be individualized for each patient based on aneurysm size and extent of the scarring process into the septum and subvalvular mitral apparatus.