Background： In patients with nonvalvular atrial fibrillation （NVAF）, embolic stroke is thought to be associated with left atrial appendage （LAA） thrombi. The WATCHMAN LAA Occlusion Device has been shown to be non...Background： In patients with nonvalvular atrial fibrillation （NVAF）, embolic stroke is thought to be associated with left atrial appendage （LAA） thrombi. The WATCHMAN LAA Occlusion Device has been shown to be noninferior to conventional oral anticoagulation with warfarin for stroke prevention in patients with NVAF. This study aimed to evaluate the procedural feasibility, safety and 12-month outcomes of the WATCHMAN LAA Occlusion Device in NVAF patients with high risk for stroke in China. Methods： The clinical data of 106 NVAF patients, who were consecutively underwent LAA closure with the WATCHMAN Device between April 2014 and May 2015, were collected. Patients were followed up at 1,3, 6, and 12 months after discharge. A transesophageal echocardiograph was performed at 45 days after implantation and repeated in case of an unexpected event during the follow-up period. Results： This study included 106 NVAF patients with a mean age of 64.2 ± 8.6 years （ranging from 50 to 88 years）, and the mean CHA,DS,-VASc score of all patients was 3.6 ± 1.6 （ranging from 2 to 9）. Among those 106 NVAF patients, 100 （94.3%） patients were implanted with the device successfully. The procedural success rate was 94.3% （100/106）, and the occlusion rate was 100.0% （100/100）. There were one tamponade, one ischemic stroke, and eight minor pericardial effusions during hospitalization. During 12-month follow-up period, two patients developed a tbrombus layer on the device that resolved with additional anticoagulation： one with visible device-thrombus experienced transient ischemic stroke, and one had a hemorrhagic stroke. There were no deaths in this study. The overall survival rate was 100.0%, and nonmajor adverse event rate was 95.0% （95/100）. In this study, the expected annual rate ofischemic stroke risk in these patients according to the CHA2DS2-VASc score was 4.0%, while the observed ischemic stroke rate was 2.0% per year. Conclusions： LAA closure with the WATCHMAN Device was feasible, efficien展开更多
Transcatheter closure of the left atrial appendage has been developed as an alternative to chronic oral anticoagulation for stroke prevention in patients with atrial fibrillation, and as a primary therapy for patients...Transcatheter closure of the left atrial appendage has been developed as an alternative to chronic oral anticoagulation for stroke prevention in patients with atrial fibrillation, and as a primary therapy for patients with contraindications to chronic oral anticoagulation. The promise of this new intervention compared with warfarin has been supported by several, small studies and two pivotal randomized trial with the Watchman Device. The results regarding risk reduction for stroke have been favourable although acute complications were not infrequent. Procedural complications, which are mainly related to transseptal puncture and device implantation, include air embolism, pericardial effusions/tamponade and device embolization. Knowledge of nature, management and prevention of complications should minimize the risk of complications and allow transcatheter left atrial appendage closure to emerge as a therapeutic option for patients with atrial fibrillation at risk for cardioembolic stroke.展开更多
Background The left atrial appendage （LAA） is an important source of thrombus formation. We investigated the feasibility of the recently developed real-time three-dimensional transesophageal echocardiography （RT3D-...Background The left atrial appendage （LAA） is an important source of thrombus formation. We investigated the feasibility of the recently developed real-time three-dimensional transesophageal echocardiography （RT3D-TEE） method in assessment of the morphology and function of the LAA. Methods Ninety-six consecutive patients （58 males with a mean age of （43.4±12.5） years） who were referred for 2-dimensional （2D） transesophageal echocardiography （TEE） underwent additional RT3D-TEE. LAA morphology was visualized in multiple views. Orifice size, depth, volumes and ejection fraction （EF） of the LAA, were measured. Results All the patients underwent RT3D-TEE examination without complications. Ninety-two patients （95.8%） had adequate images for visualization and quantitative analysis of the LAA. The LAA exhibited great variability with respect to relative dimensions and morphology. LAA orifice area was （3.8±1.2） cm^2 with a diameter of （2.4±0.9） cm x （1.4±0.6） cm. The mean depth of the LAA was （2.9±0.7） cm. End-diastolic volume （EDV-LAA）, end-systolic volume （ESV-LAA） and EF of the LAA were （6.2±3.7） ml, （4.1±2.8） ml, and 0.35±0.16, respectively. EDV-LAA, ESV-LAA and the orifice area of the LAA in patients with atrial fibrillation （AF） were larger than those without AF, whereas the EF was smaller in the AF patients. Conclusions Defining LAA morphology and quantitative analysis of the size and function of the LAA with superior quality and resolution of images using RT3D-TEE is feasible. This technique may be an ideal tool for guidance of the LAA occlusion procedure. Determination of LAA volumes and volume-derived EF by RT3D-TEE provides new insights into the analysis of LAA function.展开更多
Background The left atrial appendage （LAA） is thought to be the main source of thrombi in patients with atrial fibrillation （AF）. The purpose of this study was to describe the LAA orifice diameter, LAA length, and...Background The left atrial appendage （LAA） is thought to be the main source of thrombi in patients with atrial fibrillation （AF）. The purpose of this study was to describe the LAA orifice diameter, LAA length, and morphologic type of the LAA in Chinese patients with AF as well as to evaluate whether these LAA parameters are associated with a history of stroke in patients with AF from a single center in China. Methods The study population consisted of 219 consecutive patients with drug-refractory, symptomatic paroxysmal, or persistent AF scheduled to undergo radiofrequency catheter ablation in our single center. All patients underwent extensive clinical assessment and multidetector computed tomography to fully explore the anatomy of the LAA. Results Of the 219 patients who underwent catheter ablation procedures, chicken wing LAA morphology was found in 114 patients （52.2%）, windsock in 52 （23.9%）, cauliflower in 29 （13.0%）, and cactus in 24 （10.9%）. Compared with the windsock LAA morphology, cactus had a larger left atrial diameter （（42.40±3.68） and （37.91±4.32） mm, P=-0.005） and LAA orifice diameter （（27.38±3.70） and （24.14±3.58） mm, P=0.048）. The LAA length was significantly larger in the chicken wing morphology than in the windsock （（37.50±6.74） and （31.33±3.92） ram, P=0.015） and cauliflower morphologies （（37.50±6.74） and （31.33±3.92） mm, P=-0.015）. According to their medical records, 26 patients （11.9%） had suffered a prior stroke. Compared with patients who had no history of stroke, the prior-stroke patients were older （62.04±8.07 and 58.24±9,24, P=-0.047） and there were fewer patients with chicken wing （23.1% and 59.1%, P=-0.001） and more patients with cauliflower （26.9% and 9.8%, P=-0.046）. Multivariate Logistic regression analysis demonstrated that age （odds ratio （OR） 1.26; 95% confidence interval （CI） 1.08-1.47; P=0.003）, non-chicken wing morphology （OR 5.82; 95% CI 1.61- 21.03; P=-0.007）, an展开更多
Background:Catheter ablation is effective in restoring sinus rhythm and left atrial appendage closure(LAAC)is increasingly used for stroke prevention in patients with atrial fibrillation(AF).We aimed to observe the fe...Background:Catheter ablation is effective in restoring sinus rhythm and left atrial appendage closure(LAAC)is increasingly used for stroke prevention in patients with atrial fibrillation(AF).We aimed to observe the feasibility and safety of performing AF ablation and LAAC in a single(one-stop)procedure.Methods:Consecutive AF patients who underwent the combined procedure of AF ablation and LAAC with WATCHMAN device between March 2017 and September 2018 were prospectively enrolled.Baseline and intra-procedural parameters were evaluated.Three-month and subsequent 1-year follow-up were performed in all and earlier-enrolled subjects,respectively.Results:A total of 178 AF patients(94 males,68.9±8.1 years)underwent the one-stop procedure with CHA2DS2-VASc score 3.3±1.5 and HAS-BLED score 1.6±1.0,respectively.Pulmonary vein isolation was achieved in all patients while additional linear ablation was applied if the operator deemed necessary,yielding immediate ablation success rate of 98.9%(176/178).In the subsequent LAAC,satisfactory seal(residual leak<5 mm)was achieved in all patients.One stroke and four cardiac perforations occurred peri-operatively.At 3-month follow-up,sinus rhythm and satisfactory seal were maintained in 153/178(86.0%)and 178/178(100%)patients,respectively.One stroke and one delayed cardiac tamponade occurred,while no device-related thrombus or device migration was observed.During the 1-year follow-up for the earlier enrolled subjects,52/72(72.2%)of the patients maintained sinus rhythm.There was no stroke or systemic embolism observed.Conclusion:Combining catheter ablation and LAAC in a single procedure can be successfully and safely performed in non-valvular AF patients of Chinese population.展开更多
Attitude maneuver of liquid-filled spacecraft with an appendage as a cantilever beam by momentum wheel is studied. The dynamic equations are derived by conserva- tion of angular momentum and force equilibrium principl...Attitude maneuver of liquid-filled spacecraft with an appendage as a cantilever beam by momentum wheel is studied. The dynamic equations are derived by conserva- tion of angular momentum and force equilibrium principle. A feedback control strategy of the momentum wheel is ap- plied for the attitude maneuver. The residual nutation of the spacecraft in maneuver process changes with some chosen parameters, such as steady state time, locations of the liq- uid container and the appendage, and appendage parame- ters. The results indicate that locations in the second and fourth quadrants of the body-fixed coordinate system and the second quadrant of the wall of the main body are better choices for.placing the liquid containers and the appendage than other locations if they can be placed randomly. Higher density and thicker cross section are better for lowering the residual nutation if they can be changed. Light appendage can be modeled as a rigid body, which results in a larger residual nutation than a flexible model though. The resid- ual nutation decreases with increasing absolute value of the initial sloshing angular height.展开更多
In engineering applications (Like an ocean riser), fluid flow around bluff bodies generates substantial resistance, which can jeopardize structural integrity, lifespan, and escalate resource consumption. Therefore, em...In engineering applications (Like an ocean riser), fluid flow around bluff bodies generates substantial resistance, which can jeopardize structural integrity, lifespan, and escalate resource consumption. Therefore, employing drag reduction measures becomes particularly crucial. This paper employs the immersed boundary method to investigate the impact of transversely oriented appendage plate flexibility on the drag of cylinders under different Reynolds numbers and distances. The results indicate that flexible appendage plate exerts drag reduction effects on the downstream cylinder, with this effect gradually diminishing as Reynolds numbers increase. At identical Reynolds numbers, the drag reduction effect initially increases and then decreases with distance, with the optimal drag reduction distance observed at D = 2.5. Compared to cylinders without appendage plate, the maximum drag reduction achieved is 30.551%. Addressing the drag reduction issue in cylinders holds significant importance for ensuring engineering structural integrity, enhancing engineering efficiency, and developing novel underwater towing systems.展开更多
Background：Metabolic syndrome （MS） is a risk factor for stroke and thromboembolism event.Left atrial or LA appendage （LA/LAA） thrombus is a surrogate of potential stroke.The relationship between MS and atrial thr...Background：Metabolic syndrome （MS） is a risk factor for stroke and thromboembolism event.Left atrial or LA appendage （LA/LAA） thrombus is a surrogate of potential stroke.The relationship between MS and atrial thrombus remains unclear.In this study,we sought to investigate the effect of MS on risk stratification of LA/LAA thrombus formation in patients with nonvalvular atrial fibrillation （NVAF）.Methods：This cross-sectional study enrolled 294 consecutive NVAF patients without prior anticoagulant and lipid-lowering therapies.LA/LAA thrombus was determined by transesophageal echocardiography.Risk assessment of LA/LAA thrombus was performed using the CHADS2,CHA2DS2-VASc,MS,CHADS2-MS,and CHA2DS2-VASc-MS scores.Logistic regression analyses were performed to determine which factors were significantly related to LA/LAA thrombus.Odds ratio （OR） including 95% confidence interval was also calculated.The predictive powers of different scores for the risk of LA/LAA thrombus were represented by C-statistics and compared by receiver operating characteristic （ROC） analysis.Results：LA/LAA thrombi were identified in 56 patients （19.0%）.Logistic analysis showed that MS was the strongest risk factor for LA/LAA thrombus in NVAF patients （OR =14.698,P 〈 0.001）.ROC curve analyses revealed that the C-statistics of CHADS2-MS and CHA2DS2-VASc-MS was significantly higher than those of CHADS2 and CHA2DS2-VASc scores （CHADS2-MS vs.CHADS2,0.807 vs.0.726,P=0.0019）.Furthermore,MS was helpful for identifying individuals with a high risk of LA/LAA thrombus in the population with a low risk of stroke （CHADS2 or CHA2DS2-VASc score =0）.Conclusions：MS is associated with LA/LAA thrombus risk in patients with NVAF.In addition to the CHADS2 and CHA2DS2-VASc scores,the CHADS2-MS and CHA2DS2-VASc-MS scores provide additional information on stroke risk assessment.展开更多
Patient with atrial fibrillation(AF) are at risk of developing stroke with the left atrial appendage(LAA) being the most common site for thrombus formation. If left untreated, AF is associated with 4 to 5 folds increa...Patient with atrial fibrillation(AF) are at risk of developing stroke with the left atrial appendage(LAA) being the most common site for thrombus formation. If left untreated, AF is associated with 4 to 5 folds increase in the risk of ischemic stroke in all age groups. About 5% to 15% of AF patients have atrial thrombi on transesophageal echocardiography, and 91% of those thrombi are located in the LAA in patient with nonrheumatic AF. Although oral anticoagulants are the gold-standard treatment for stroke prevention in patients with non-valvular AF,some patients are at high risk of bleeding and deemed not candidates for anticoagulation. Therefore, LAA occlusion(LAAO) has emerged as alternative approach for stroke prevention in those patients. Surgical LAAO is associated with high rate of unsuccessful closure and recommended only in patients with AF and undergoing cardiac surgery. Percutaneous LAAO uses transvenous access with trans-septal puncture and was first tested using the PLAATO device.Watchman is the most common and only Food and Drug Administration(FDA)approved device for LAAO. LAAO using Watchman device is non-inferior to warfarin therapy in preventing ischemic stroke/systemic thromboembolism.However, it is associated with lower rates of hemorrhagic stroke, bleeding and death. Amplatzer is another successful LAAO device that has CE mark and is waiting for FDA approval. Optimal antithrombotic therapy post LAAO is still under debate and highly patient-specific. The aim of this paper is to systematically review the current literature to evaluate the efficacy and safety of different LAAO devices.展开更多
BACKGROUND Inflammatory indices derived from complete blood tests have been reported to be associated with poor outcomes in patients with atrial fibrillation(AF).The data about the relationship between inflammatory in...BACKGROUND Inflammatory indices derived from complete blood tests have been reported to be associated with poor outcomes in patients with atrial fibrillation(AF).The data about the relationship between inflammatory indices and left atrial appendage thrombus(LAAT)or dense spontaneous echo contrast(SEC)are limited.AIM To explore the value of inflammatory indices for predicting the presence of LAAT or dense SEC in nonvalvular AF patients.METHODS A total of 406 patients with nonvalvular AF who underwent transesophageal echocardiography were included and divided into two groups based on the presence(study group)or absence(control group)of LAAT or dense SEC.Inflammatory indices,including the neutrophil-to-lymphocyte ratio(NLR),platelet–tolymphocyte ratio(PLR),and lymphocyte-to-monocyte ratio(LMR),were calculated from complete blood analysis.The associations of inflammatory indices RESULTS LAAT and dense SEC were detected in 11(2.7%)and 42(10.3%)patients,respectively.The PLR only showed an association with LAAT/dense SEC in the univariate model.Elevated NLR(odds ratio[OR]=1.48,95%confidence interval[CI]:1.11-1.98,P=0.007)and reduced LMR(OR=0.59,95%CI:0.41-0.83,P=0.003)were found to be independent risk factors for the presence of LAAT/dense SEC.The areas under the NLR and LMR curves for predicting LAAT/dense SEC were 0.73(95%CI:0.66-0.80,P<0.001)and 0.73(95%CI:0.65-0.81,P<0.001),respectively,while the cutoff values were 2.8(sensitivity:69.8%;specificity:64.0%)and 2.4(sensitivity:71.7%;specificity:60.6%),respectively.CONCLUSION Increased NLR and decreased LMR may predict LAAT/dense SEC in patients with nonvalvular AF.展开更多
文摘Background： In patients with nonvalvular atrial fibrillation （NVAF）, embolic stroke is thought to be associated with left atrial appendage （LAA） thrombi. The WATCHMAN LAA Occlusion Device has been shown to be noninferior to conventional oral anticoagulation with warfarin for stroke prevention in patients with NVAF. This study aimed to evaluate the procedural feasibility, safety and 12-month outcomes of the WATCHMAN LAA Occlusion Device in NVAF patients with high risk for stroke in China. Methods： The clinical data of 106 NVAF patients, who were consecutively underwent LAA closure with the WATCHMAN Device between April 2014 and May 2015, were collected. Patients were followed up at 1,3, 6, and 12 months after discharge. A transesophageal echocardiograph was performed at 45 days after implantation and repeated in case of an unexpected event during the follow-up period. Results： This study included 106 NVAF patients with a mean age of 64.2 ± 8.6 years （ranging from 50 to 88 years）, and the mean CHA,DS,-VASc score of all patients was 3.6 ± 1.6 （ranging from 2 to 9）. Among those 106 NVAF patients, 100 （94.3%） patients were implanted with the device successfully. The procedural success rate was 94.3% （100/106）, and the occlusion rate was 100.0% （100/100）. There were one tamponade, one ischemic stroke, and eight minor pericardial effusions during hospitalization. During 12-month follow-up period, two patients developed a tbrombus layer on the device that resolved with additional anticoagulation： one with visible device-thrombus experienced transient ischemic stroke, and one had a hemorrhagic stroke. There were no deaths in this study. The overall survival rate was 100.0%, and nonmajor adverse event rate was 95.0% （95/100）. In this study, the expected annual rate ofischemic stroke risk in these patients according to the CHA2DS2-VASc score was 4.0%, while the observed ischemic stroke rate was 2.0% per year. Conclusions： LAA closure with the WATCHMAN Device was feasible, efficien
文摘Transcatheter closure of the left atrial appendage has been developed as an alternative to chronic oral anticoagulation for stroke prevention in patients with atrial fibrillation, and as a primary therapy for patients with contraindications to chronic oral anticoagulation. The promise of this new intervention compared with warfarin has been supported by several, small studies and two pivotal randomized trial with the Watchman Device. The results regarding risk reduction for stroke have been favourable although acute complications were not infrequent. Procedural complications, which are mainly related to transseptal puncture and device implantation, include air embolism, pericardial effusions/tamponade and device embolization. Knowledge of nature, management and prevention of complications should minimize the risk of complications and allow transcatheter left atrial appendage closure to emerge as a therapeutic option for patients with atrial fibrillation at risk for cardioembolic stroke.
文摘Background The left atrial appendage （LAA） is an important source of thrombus formation. We investigated the feasibility of the recently developed real-time three-dimensional transesophageal echocardiography （RT3D-TEE） method in assessment of the morphology and function of the LAA. Methods Ninety-six consecutive patients （58 males with a mean age of （43.4±12.5） years） who were referred for 2-dimensional （2D） transesophageal echocardiography （TEE） underwent additional RT3D-TEE. LAA morphology was visualized in multiple views. Orifice size, depth, volumes and ejection fraction （EF） of the LAA, were measured. Results All the patients underwent RT3D-TEE examination without complications. Ninety-two patients （95.8%） had adequate images for visualization and quantitative analysis of the LAA. The LAA exhibited great variability with respect to relative dimensions and morphology. LAA orifice area was （3.8±1.2） cm^2 with a diameter of （2.4±0.9） cm x （1.4±0.6） cm. The mean depth of the LAA was （2.9±0.7） cm. End-diastolic volume （EDV-LAA）, end-systolic volume （ESV-LAA） and EF of the LAA were （6.2±3.7） ml, （4.1±2.8） ml, and 0.35±0.16, respectively. EDV-LAA, ESV-LAA and the orifice area of the LAA in patients with atrial fibrillation （AF） were larger than those without AF, whereas the EF was smaller in the AF patients. Conclusions Defining LAA morphology and quantitative analysis of the size and function of the LAA with superior quality and resolution of images using RT3D-TEE is feasible. This technique may be an ideal tool for guidance of the LAA occlusion procedure. Determination of LAA volumes and volume-derived EF by RT3D-TEE provides new insights into the analysis of LAA function.
基金This study was supported by grants from the Key Project of Hubei Science and Technology Support Program （No. 2013BCB013）, the Key Project of Hubei Natural Science Foundation （No. 2013CFA059）, and the National Natural Science Foundation of China （No. 81270249）.
文摘Background The left atrial appendage （LAA） is thought to be the main source of thrombi in patients with atrial fibrillation （AF）. The purpose of this study was to describe the LAA orifice diameter, LAA length, and morphologic type of the LAA in Chinese patients with AF as well as to evaluate whether these LAA parameters are associated with a history of stroke in patients with AF from a single center in China. Methods The study population consisted of 219 consecutive patients with drug-refractory, symptomatic paroxysmal, or persistent AF scheduled to undergo radiofrequency catheter ablation in our single center. All patients underwent extensive clinical assessment and multidetector computed tomography to fully explore the anatomy of the LAA. Results Of the 219 patients who underwent catheter ablation procedures, chicken wing LAA morphology was found in 114 patients （52.2%）, windsock in 52 （23.9%）, cauliflower in 29 （13.0%）, and cactus in 24 （10.9%）. Compared with the windsock LAA morphology, cactus had a larger left atrial diameter （（42.40±3.68） and （37.91±4.32） mm, P=-0.005） and LAA orifice diameter （（27.38±3.70） and （24.14±3.58） mm, P=0.048）. The LAA length was significantly larger in the chicken wing morphology than in the windsock （（37.50±6.74） and （31.33±3.92） ram, P=0.015） and cauliflower morphologies （（37.50±6.74） and （31.33±3.92） mm, P=-0.015）. According to their medical records, 26 patients （11.9%） had suffered a prior stroke. Compared with patients who had no history of stroke, the prior-stroke patients were older （62.04±8.07 and 58.24±9,24, P=-0.047） and there were fewer patients with chicken wing （23.1% and 59.1%, P=-0.001） and more patients with cauliflower （26.9% and 9.8%, P=-0.046）. Multivariate Logistic regression analysis demonstrated that age （odds ratio （OR） 1.26; 95% confidence interval （CI） 1.08-1.47; P=0.003）, non-chicken wing morphology （OR 5.82; 95% CI 1.61- 21.03; P=-0.007）, an
基金This work was supported by grants from the State Key Program of National Natural Science Foundation of China(No.81530015)Clinical Research Plan of SHDC(No.16CR2019A).
文摘Background:Catheter ablation is effective in restoring sinus rhythm and left atrial appendage closure(LAAC)is increasingly used for stroke prevention in patients with atrial fibrillation(AF).We aimed to observe the feasibility and safety of performing AF ablation and LAAC in a single(one-stop)procedure.Methods:Consecutive AF patients who underwent the combined procedure of AF ablation and LAAC with WATCHMAN device between March 2017 and September 2018 were prospectively enrolled.Baseline and intra-procedural parameters were evaluated.Three-month and subsequent 1-year follow-up were performed in all and earlier-enrolled subjects,respectively.Results:A total of 178 AF patients(94 males,68.9±8.1 years)underwent the one-stop procedure with CHA2DS2-VASc score 3.3±1.5 and HAS-BLED score 1.6±1.0,respectively.Pulmonary vein isolation was achieved in all patients while additional linear ablation was applied if the operator deemed necessary,yielding immediate ablation success rate of 98.9%(176/178).In the subsequent LAAC,satisfactory seal(residual leak<5 mm)was achieved in all patients.One stroke and four cardiac perforations occurred peri-operatively.At 3-month follow-up,sinus rhythm and satisfactory seal were maintained in 153/178(86.0%)and 178/178(100%)patients,respectively.One stroke and one delayed cardiac tamponade occurred,while no device-related thrombus or device migration was observed.During the 1-year follow-up for the earlier enrolled subjects,52/72(72.2%)of the patients maintained sinus rhythm.There was no stroke or systemic embolism observed.Conclusion:Combining catheter ablation and LAAC in a single procedure can be successfully and safely performed in non-valvular AF patients of Chinese population.
基金supported by the National Natural Science Foundation of China (11072030)
文摘Attitude maneuver of liquid-filled spacecraft with an appendage as a cantilever beam by momentum wheel is studied. The dynamic equations are derived by conserva- tion of angular momentum and force equilibrium principle. A feedback control strategy of the momentum wheel is ap- plied for the attitude maneuver. The residual nutation of the spacecraft in maneuver process changes with some chosen parameters, such as steady state time, locations of the liq- uid container and the appendage, and appendage parame- ters. The results indicate that locations in the second and fourth quadrants of the body-fixed coordinate system and the second quadrant of the wall of the main body are better choices for.placing the liquid containers and the appendage than other locations if they can be placed randomly. Higher density and thicker cross section are better for lowering the residual nutation if they can be changed. Light appendage can be modeled as a rigid body, which results in a larger residual nutation than a flexible model though. The resid- ual nutation decreases with increasing absolute value of the initial sloshing angular height.
文摘In engineering applications (Like an ocean riser), fluid flow around bluff bodies generates substantial resistance, which can jeopardize structural integrity, lifespan, and escalate resource consumption. Therefore, employing drag reduction measures becomes particularly crucial. This paper employs the immersed boundary method to investigate the impact of transversely oriented appendage plate flexibility on the drag of cylinders under different Reynolds numbers and distances. The results indicate that flexible appendage plate exerts drag reduction effects on the downstream cylinder, with this effect gradually diminishing as Reynolds numbers increase. At identical Reynolds numbers, the drag reduction effect initially increases and then decreases with distance, with the optimal drag reduction distance observed at D = 2.5. Compared to cylinders without appendage plate, the maximum drag reduction achieved is 30.551%. Addressing the drag reduction issue in cylinders holds significant importance for ensuring engineering structural integrity, enhancing engineering efficiency, and developing novel underwater towing systems.
基金This study was supported by the National Natural Science Foundation project （No.81670364） and Natural Science Foundation of Guangdong Province （No. 2016A030313356）.
文摘Background：Metabolic syndrome （MS） is a risk factor for stroke and thromboembolism event.Left atrial or LA appendage （LA/LAA） thrombus is a surrogate of potential stroke.The relationship between MS and atrial thrombus remains unclear.In this study,we sought to investigate the effect of MS on risk stratification of LA/LAA thrombus formation in patients with nonvalvular atrial fibrillation （NVAF）.Methods：This cross-sectional study enrolled 294 consecutive NVAF patients without prior anticoagulant and lipid-lowering therapies.LA/LAA thrombus was determined by transesophageal echocardiography.Risk assessment of LA/LAA thrombus was performed using the CHADS2,CHA2DS2-VASc,MS,CHADS2-MS,and CHA2DS2-VASc-MS scores.Logistic regression analyses were performed to determine which factors were significantly related to LA/LAA thrombus.Odds ratio （OR） including 95% confidence interval was also calculated.The predictive powers of different scores for the risk of LA/LAA thrombus were represented by C-statistics and compared by receiver operating characteristic （ROC） analysis.Results：LA/LAA thrombi were identified in 56 patients （19.0%）.Logistic analysis showed that MS was the strongest risk factor for LA/LAA thrombus in NVAF patients （OR =14.698,P 〈 0.001）.ROC curve analyses revealed that the C-statistics of CHADS2-MS and CHA2DS2-VASc-MS was significantly higher than those of CHADS2 and CHA2DS2-VASc scores （CHADS2-MS vs.CHADS2,0.807 vs.0.726,P=0.0019）.Furthermore,MS was helpful for identifying individuals with a high risk of LA/LAA thrombus in the population with a low risk of stroke （CHADS2 or CHA2DS2-VASc score =0）.Conclusions：MS is associated with LA/LAA thrombus risk in patients with NVAF.In addition to the CHADS2 and CHA2DS2-VASc scores,the CHADS2-MS and CHA2DS2-VASc-MS scores provide additional information on stroke risk assessment.
文摘Patient with atrial fibrillation(AF) are at risk of developing stroke with the left atrial appendage(LAA) being the most common site for thrombus formation. If left untreated, AF is associated with 4 to 5 folds increase in the risk of ischemic stroke in all age groups. About 5% to 15% of AF patients have atrial thrombi on transesophageal echocardiography, and 91% of those thrombi are located in the LAA in patient with nonrheumatic AF. Although oral anticoagulants are the gold-standard treatment for stroke prevention in patients with non-valvular AF,some patients are at high risk of bleeding and deemed not candidates for anticoagulation. Therefore, LAA occlusion(LAAO) has emerged as alternative approach for stroke prevention in those patients. Surgical LAAO is associated with high rate of unsuccessful closure and recommended only in patients with AF and undergoing cardiac surgery. Percutaneous LAAO uses transvenous access with trans-septal puncture and was first tested using the PLAATO device.Watchman is the most common and only Food and Drug Administration(FDA)approved device for LAAO. LAAO using Watchman device is non-inferior to warfarin therapy in preventing ischemic stroke/systemic thromboembolism.However, it is associated with lower rates of hemorrhagic stroke, bleeding and death. Amplatzer is another successful LAAO device that has CE mark and is waiting for FDA approval. Optimal antithrombotic therapy post LAAO is still under debate and highly patient-specific. The aim of this paper is to systematically review the current literature to evaluate the efficacy and safety of different LAAO devices.
基金Public Welfare Technology Project of Ningbo Science and Technology Bureau,No.2023S140Medical Health Science and Technology Project of Zhejiang Province Health Commission,No.2024KY1518.
文摘BACKGROUND Inflammatory indices derived from complete blood tests have been reported to be associated with poor outcomes in patients with atrial fibrillation(AF).The data about the relationship between inflammatory indices and left atrial appendage thrombus(LAAT)or dense spontaneous echo contrast(SEC)are limited.AIM To explore the value of inflammatory indices for predicting the presence of LAAT or dense SEC in nonvalvular AF patients.METHODS A total of 406 patients with nonvalvular AF who underwent transesophageal echocardiography were included and divided into two groups based on the presence(study group)or absence(control group)of LAAT or dense SEC.Inflammatory indices,including the neutrophil-to-lymphocyte ratio(NLR),platelet–tolymphocyte ratio(PLR),and lymphocyte-to-monocyte ratio(LMR),were calculated from complete blood analysis.The associations of inflammatory indices RESULTS LAAT and dense SEC were detected in 11(2.7%)and 42(10.3%)patients,respectively.The PLR only showed an association with LAAT/dense SEC in the univariate model.Elevated NLR(odds ratio[OR]=1.48,95%confidence interval[CI]:1.11-1.98,P=0.007)and reduced LMR(OR=0.59,95%CI:0.41-0.83,P=0.003)were found to be independent risk factors for the presence of LAAT/dense SEC.The areas under the NLR and LMR curves for predicting LAAT/dense SEC were 0.73(95%CI:0.66-0.80,P<0.001)and 0.73(95%CI:0.65-0.81,P<0.001),respectively,while the cutoff values were 2.8(sensitivity:69.8%;specificity:64.0%)and 2.4(sensitivity:71.7%;specificity:60.6%),respectively.CONCLUSION Increased NLR and decreased LMR may predict LAAT/dense SEC in patients with nonvalvular AF.
