Lower gastrointestinal bleeding:Role of 64-row computed tomographic angiography in diagnosis and therapeutic planning

AIM: To determine the value of computed tomographic angiography(CTA) for diagnosis and therapeutic planning in lower gastrointestinal(GI) bleeding.METHODS: Sixty-three consecutive patients with acute lower GI bleeding underwent CTA before endovascular or surgical treatment. CTA was used to determine whether the lower GI bleeding was suitable for endovascular treatment, surgical resection, or conservative treatment in each patient. Treatment planning with CTA was compared with actual treatment decisions or endovascular or surgical treatment that had been carried out in each patient based on CTA findings.RESULTS: 64-row CTA detected active extravasation of contrast material in 57 patients and six patients had no demonstrable active bleeding, resulting in an accuracy of 90.5% in the detection of acute GI bleeding(57 of 63). In three of the six patients with no demonstrable active bleeding, active lower GI bleeding recurred within one week after CTA, and angiography revealed acute bleeding. The overall location-based accuracy, sensitivity, specificity, positive predictive value(PPV) and negative predictive value(NPV) for the detection of GI bleeding by 64-row CTA were 98.8%(249 of 252), 95.0%(57 of 60), 100%(192 of 192), 100%(57 of 57), and 98.5%(192 of 195), respectively. Treatment planning was correctly established on the basis of 64-row CTA with an accuracy, sensitivity, specificity, PPV and NPV of 98.4%(248 of 252), 93.3%(56 of 60), 100%(192 of 192), 100%(56 of 56), and 97.5%(192 of 196), respectively, in a location-based evaluation. CONCLUSION: 64-row CTA is safe and effective in making decisions regarding treatment, without performing digital subtraction angiography or surgery, in the majority of patients with lower GI bleeding.

nfluences of superheat and cooling intensity on macrostructure and macrosegregation of duplex stainless steel studied by thermal simulation

The influences of superheat and cooling intensity on macrostructure and macrosegregation of one new kind duplex stainless steel(DSS)were studied.Thermal simulation equipment was applied to prepare samples,which could reproduce the industrial processes of DSS manufactured by a vertical continuous slab caster.Macrostructure and macrosegregation were analyzed using the digital single lens reflex and laser-induced breakdown spectroscope(LIBSOPA-200),respectively.The percentage of both chill zone and center equiaxed zone increases with the superheat decreasing,while that of the columnar zone decreases.There is only equiaxed grain existing as the superheat is 10 and 20℃.The lower the superheat is,the coarser the gain size is.High cooling intensity in mold could remarkably decrease the chill zone length and refine the grains in chill zone and center equiaxed zone.The influences of cooling intensity on macrosegregation are greater than those of superheat.The macrosegregation of Si,Mn and Cr is slightly dependent on superheat,while that of Cu,Mo and Ni changes greatly with superheat increasing.

Safety and Necessity of Antiplatelet Therapy on Patients Underwent Endovascular Aortic Repair with Both Stanford Type B Aortic Dissection and Coronary Heart Disease

Background： Acute aortic dissection is known as the most dangerous aortic disease, with management and prognosis determined as the disruption of the medial layer provoked by intramural bleeding. The objective of this study was to evaluate the safety and necessity of antiplatelet therapy on patients with Stanford Type B aortic dissection （TBAD） who underwent endovascular aortic repair （EVAR）. Methods： The present study retrospectively analyzed 388 patients with TBAD who underwent EVAR and coronary angiography. The primary outcomes were hemorrhage, death, endoleak, recurrent dissection, myocardial infarction, and cerebral infarction in patients with and without aspirin antiplatelet therapy at 1 month and 12 months. Results： Of those 388 patients, 139 （35.8%） patients were treated with aspirin and 249 （64.2%） patients were not treated with aspirin. Patients in the aspirin group were elderly （57.0 ± 10.3 years vs. 52.5 ± 11.9 years, respectively, χ2 = 3.812, P 〈 0.001） and had more hypertension （92.1% vs. 83.9%, respectively, χ2 = 5.191, P = 0.023） and diabetes （7.2% vs. 2.8%, respectively, χ2 = 4.090, P = 0.043） than in the no-aspirin group. Twelve patients （aspirin group vs. no-aspirin group; 3.6% vs. 2.8%, respectively, χ2 = 0.184, P = 0.668） died at 1-month follow-up, while the number was 18 （4.6% vs. 5.0%, respectively, χ2 = 0.027, P = 0.870） at 12-month follow-up. Hemorrhage occurred in 1 patient （Bleeding Academic Research Consortium [BARC] Type 2） of the aspirin group, and 3 patients （1 BARC Type 2 and 2 BARC Type 5） in the no-aspirin group at 1-month follow-up （ χ2 = 0.005, P = 0.944）. New hemorrhage occurred in five patients in the no-aspirin group at 12-month follow-up. Three patients in the aspirin group while five patients in the no-aspirin group had recurrent dissection for endoleak at 1-month follow-up （2.3% vs. 2.2%, respectively, χ2 = 0.074, P = 0.816）. Four patients had new dissection in the no-aspirin group at 12-month follow-up （2.3% vs. 3.8%, respectively, χ2 = 0.194, P = 0.660）. Each group had one patient with myocardial infarction at 1-month follow-up （0.8% vs. 0.4%, respectively, χ2 = 0.102, P = 0.749） and one more patient in the no-aspirin group at 12-month follow-up. No one had cerebral infarction in both groups during the 12-month follow-up. In the percutaneous coronary intervention （PCI） subgroup, 44 （31.7%） patients had taken dual-antiplatelet therapy （DAPT, aspirin ＋ clopidogrel） and the other 95 （68.3%） patients had taken only aspirin. There was no significant difference in hemorrhage （0% vs. 1.1%, respectively,χ2 = 0.144, P = 0.704）, death （4.8% vs. 4.5%, respectively, χ2 = 0.154, P = 0.695）, myocardial infarction （2.4% vs. 0%, respectively,χ2 = 0.144, P = 0.704）, endoleak, and recurrent dissection （0% vs. 3.4%, respectively, χ2 = 0.344, P = 0.558） between the two groups at 12-month follow-up. Conclusions： The present study indicated that long-term oral low-dose aspirin was safe for patients with both TBAD and coronary heart disease who underwent EVAR. For the patients who underwent both EVAR and PCI, DAPT also showed no increase in hemorrhage, endoleak, recurrent dissection, death, and myocardial infarction.

Correlation between Sex and Prognosis of Acute Aortic Dissection in the Chinese Population

Background： The prevalence, presentation, management, and prognosis of coronary heart disease differ according to sex. Greater understanding on the differences between men and women with acute aortic dissection （AAD） is needed. We aimed to investigate whether sex disparities are found in patients with AAD, and to study sex differences in complications, mortality in-hospital, and tong-term. Methods： We included 884 patients enrolled in our institute between June 2002 and May 2016. Considering psychosocial factors, treatments, and the outcomes in men versus those in women with AAD, we explored the association of sex with psychosocial characteristics and mortality risk. For categorical variables, significant differences between groups were assessed with the Chi-square test or Fisher＇s exact test, and continuous parameters were assessed with Student＇s t-test. Univariate and stratified survival statistics were computed using Kaplan-Meier analysis. Results： A total of 884 patients （76.1% male, mean age 51.4 ± 11.8 years） were inchidcd in this study. There were fewer current smokers in female compared with male （ 17.5% vs. 67.2%,χ^2= 160.06, P〈 0.05）. The percentage of men who reported regular alcohol consumption was significantly higher than that in women （40.6% vs. 3.8%, χ^2== 100.18, P 〈 0.05）. About 6.2% （55 of 884） of patients with AAD died before vascular or endovascular surgery was performed, 34.4% （304 of 884） of patients underwent surgical procedures, and 52.7% （466 of 884） and 12.8% （113 of 884） of patients received endovascular treatment and medication, Postoperative mortality similar （6.0% vs. 5.6%, respectively, χ^2= 0.03, P = 0.91） between men and women. Follow-up was completed in 653 of 829 patients （78.8%）. Adjustment for age, history of coronary disease, hypertension, smoking and drinking, Type A and use of beta-blocker, angiotensin II receptor blockers, angiotensin converting enzyme （ACE） inhibitor, calcium-channel blockers and statins by multivariate logistic regression analysis suggested that age （odds ratios [ORs], 1.04; 95% confidence interval [CI], 1.01-1.07; P 〈 0.05）, using of calcium-channel blockers （OR, 0.37： 95% CI, 0.18-0.74; P 〈 0.05）, at discharge were independent predictors of late mortality, ACE inhibitors （OR, 1.91： 95% CI, 1.03-3.54： P = 0.04） was independent risk factor of late mortality.Conclusions： In Chinese with AAD, sex is not independently associated with long-term clinical outcomes. Age, the intake of calcium-channel blockers at discharge might help to improve long-term otitcomes.

Effects of pulse magneto-oscillation on GCr15 bearing steel continuous casting billet

Pulse magneto-oscillation(PMO)added during solidification could affect the solidification structure and macrosegregation.A modified thermal simulation equipment was applied to prepare GCr15 bearing steel continuous casting billets with different PMO peak currents.Then,metallographic analysis,component analysis and numerical simulation were adopted to study the influence of PMO peak current and its mechanism.The sample with 150 K_(I)A PMO peak current treatment has little difference with the samples without PMO treatment on solidification structure and macrosegregation.As the peak currents are 250 and 350 K_(I)A,the columnar zone increases and macrosegregation aggravated.When 450 K_(I)A peak current is selected,the equiaxed grain ratio is enlarged,and the dendritic grains are refined,and the macrosegregation of C,Cr,Si and Mn is decreased significantly.By analyzing,different convections induced by PMO with various peak currents are the key factor to change the solidification structure and macrosegregation.