BACKGROUND The prognostic value of coronary collateral circulation(CC)in patients undergoing chronic total occlusion(CTO)percutaneous coronary intervention(PCI)is underdetermined.The purpose of the study was to assess...BACKGROUND The prognostic value of coronary collateral circulation(CC)in patients undergoing chronic total occlusion(CTO)percutaneous coronary intervention(PCI)is underdetermined.The purpose of the study was to assess the prognostic value of current two CC grading systems and their association with long-term outcomes in patients with CTO underwent PCI.METHODS We consecutively enrolled patients with single-vessel CTO underwent PCI between January 2010 and December2013.All patients were categorized into well-developed or poor-developed collaterals group according to angiographic Werner's CC(grade 2 vs.grade 0–1)or Rentrop(grade 3 vs.grade 0–2)grading system.The primary endpoint was 5-year cardiac death.RESULTS Of 2452 enrolled patients,the overall technical success rate was 74.1%.Well-developed collaterals were present in686 patients(28.0%)defined by Werner's CC grade 2,and in 1145 patients(46.7%)by Rentrop grade 3.According to Werner's CC grading system,patients with well-developed collaterals had a lower rate of 5-year cardiac death compared with those with poordeveloped collaterals(1.6%vs.3.3%,P=0.02),those with suboptimal recanalization was associated with higher rate of 5-year cardiac death compared with optimal recanalization(4.7%vs.0.8%,P=0.01)and failure patients(4.7%vs.1.6%,P=0.12).However,the similar effect was not shown in Rentrop grading system.CONCLUSIONS In patients with the single-vessel CTO underwent PCI,well-developed collaterals by Werner's CC definition were associated with lower rate of 5-year cardiac death.Werner's CC grading system had a greater prognostic value than Rentrop grading system in patients with CTO underwent PCI.展开更多
Acupuncture at Shuigou(GV26) shows good clinical efficacy for treating stroke, but its mechanism remains poorly understood. In this study, a cerebral infarction model of ischemia/reperfusion injury received electroacu...Acupuncture at Shuigou(GV26) shows good clinical efficacy for treating stroke, but its mechanism remains poorly understood. In this study, a cerebral infarction model of ischemia/reperfusion injury received electroacupuncture at GV26(15 Hz and 1 m A, continuous wave [biphasic pulses], for 5 minutes). Electroacupuncture effectively promoted regional cerebral blood flow on the infarct and non-infarct sides, increased infarct lesions, lectin, and number of blood vessels, upregulated von Willebrand factor and cell proliferation marker Ki67 expression, and diminished neurological severity score. These findings confirm that electroacupuncture at GV26 promotes establishment of collateral circulation and angiogenesis, and improves neurological function.展开更多
AIM:To study characteristics of collateral circulation of gastric varices (GVs) with 64-row multidetector computer tomography portal venography (MDCTPV).METHODS:64-row MDCTPV with a slice thickness of 0.625 mm and a s...AIM:To study characteristics of collateral circulation of gastric varices (GVs) with 64-row multidetector computer tomography portal venography (MDCTPV).METHODS:64-row MDCTPV with a slice thickness of 0.625 mm and a scanning field from 2 cm above the tracheal bifurcation to the lower edge of the kidney was performed in 86 patients with GVS diagnosed by endoscopy. The computed tomography protocol included unenhanced,arterial and portal vein phases. The MDCTPV was performed on an AW4.3 workstation. GVs were classified into three types according to Sarin's Classification. The afferent and efferent veins of each type of GV were observed.RESULTS:The afferent venous drainage originated mostly from the left gastric vein alone (LGV) (28/86,32.59%),or the LGV more than the posterior gastric vein/short gastric vein [LGV > posterior gastric vein/short gastric vein (PGV/SGV)] (22/86,25.58%),as seen by MDCTPV. The most common efferent venousdrainage was via the azygos vein to the superior vena cava (53/86,61.63%),or via the gastric/splenorenal shunt (37/86,43.02%) or inferior phrenic vein (8/86,9.30%) to the inferior vena cava. In patients with gastroesophageal varices type 1,the afferent venous drainage of GV mainly originated from the LGV or LGV > PGV/SGV (43/48,89.58%),and the efferent venous drainage was mainly via the azygos vein to the super vena cava (43/48,89.58%),as well as via the gastric/splenorenal shunt (8/48,16.67%) or inferior phrenic vein (3/48,6.25%) to the inferior vena cava. In patients with gastroesophageal varices type 2,the afferent venous drainage of the GV mostly came from the PGV/SGV more than the LGV (PGV/SGV > LGV) (8/16,50%),and the efferent venous drainage was via the azygos vein (10/16,62.50%) and gastric/splenorenal shunt (9/16,56.25%). In patients with isolated gastric varices,the main afferent venous drainage was via the PGV/SGV alone (16/22,72.73%),and the efferent venous drainage was mainly via the gastric/splenorenal shunt (20/22,90.91%),as well as the inferior phrenic vein (3/23) to the inferior vena cava. CONCLUSION:MDCTPV can clearly display the afferent and efferent veins of all types of GV,and it could provide useful reference information for the clinical management of GV bleeding.展开更多
BACKGROUND Congenital coronary artery fistula can lead to symptoms of chest tightness,chest pain,or exertional dyspnea,which is a congenital vascular malformation that should not be ignored.Patients who have such malf...BACKGROUND Congenital coronary artery fistula can lead to symptoms of chest tightness,chest pain,or exertional dyspnea,which is a congenital vascular malformation that should not be ignored.Patients who have such malformations are frequently observed with different concurrent abnormal anatomic structures.Collateral circulation may have a positive effect on improving the patients'symptoms.CASE SUMMARY A 53-year-old female experienced episodic chest discomfort for the past month with symptoms manifesting when she was agitated or overexerted.After a positive treadmill test,the patient underwent coronary angiography.“Ghostlike”intermittent appearance of coronary ventricular fistula and collateral branching were observed.The patient was diagnosed with a right coronary ventricular fistula and collateral circulation.CONCLUSION This case shows the likelihood of collateral circulation in patients with coronary artery fistula.This may provide medical staff with novel solutions to treat insufficiency of myocardial blood supply induced by cardiovascular malformations.展开更多
Background:Coronary collateral circulation(CCC)plays a vital role in the myocardial blood supply,especially for ischemic myocardium.Evidence suggests that the visfatin and 25-hydroxyvitamin D_(3)[25(OH)D_(3)]levels ar...Background:Coronary collateral circulation(CCC)plays a vital role in the myocardial blood supply,especially for ischemic myocardium.Evidence suggests that the visfatin and 25-hydroxyvitamin D_(3)[25(OH)D_(3)]levels are related to the degree and incidence of vascular stenosis associated with coronary artery disease;however,few studies have evaluated the effect of visfatin and 25(OH)D_(3) on CCC development in patients with chronic total occlusion(CTO).This study aimed to evaluate the relationship between the serum visfatin and 25(OH)D_(3) levels and CCC in patients with CTO.Methods:A total of 189 patients with CTO confirmed by coronary angiography were included.CCC was graded from 0 to 3 according to the Rentrop-Cohen classification.Patients with grade 0 or grade 1 collateral development were in-cluded in the poor CCC group(n=82),whereas patients with grade 2 or grade 3 collateral development were included in the good CCC group(n=107).The serum visfatin and 25(OH)D_(3) levels were measured by ELISA.Results:The visfatin level was significantly higher in the poor CCC group than in the good CCC group,and the 25(OH)D_(3) level was significantly lower in the poor CCC group than in the good CCC group(P=0.000).Correlation analysis showed that the Rentrop grade was negatively correlated with the visfatin level(r=−0.692,P=0.000)but positively correlated with the 25(OH)D_(3) level(r=0.635,P=0.000).Logistic regression analysis showed that the vis-fatin and 25(OH)D_(3) levels were independent risk factors for CCC(odds ratio 1.597,95%confidence interval 1.300-1.961,P=0.000 and odds ratio 0.566,95%confidence interval 0.444-0.722,P=0.000,respectively).The visfatin and 25(OH)D_(3) levels can effectively predict the CCC status.Conclusion:Serum visfatin and 25(OH)D_(3) levels are related to CCC development and are independent predictors of poor CCC.展开更多
BACKGROUND: Hepatobiliary cystadenocarcinoma represents a rare epithelial malignant tumor derived from the intrahepatic bile duct. METHODS: A 71-year-old woman, who had undergone laparoscopic drainage of a cystic lesi...BACKGROUND: Hepatobiliary cystadenocarcinoma represents a rare epithelial malignant tumor derived from the intrahepatic bile duct. METHODS: A 71-year-old woman, who had undergone laparoscopic drainage of a cystic lesion of the right hepatic lobe, was misdiagnosed as having hepatic echinococcal disease, and received intracystic infusion of 95% ethanol four years ago. She was admitted to our hospital for further treatment. RESULTS: Physical examination revealed dilated superficial veins across the right abdominal wall. After mapping the direction of blood flow in these vessels, we assumed that this was a sign of inferior vena cava obstruction. Abdominal ultrasound, computed tomography, magnetic resonance imaging combined with magnetic resonance angiography showed a large cystic mass in the right upper quadrant and epigastrium, displacing the adjacent structures, adherent to the inferior vena cava, which was not patent, resulting in dilation of superficial epigastric veins. The patient underwent an exploratory laparotomy. Total excision of the huge mass measuring 16×15 cm was possible under selective vascular exclusion of the liver. Removal of the tumor resulted in immediate restoration of flow in the inferior vena cava. On the basis of the pathology and findings of immunohistochemical analysis, a hepatobiliary cystadenocarcinoma was diagnosed.CONCLUSIONS: In the present case, hepatobiliary cystadenocar-cinoma was accompanied by dilated superficial venous collaterals due to inferior vena cava obstruction. Selective vascular exclusion of the liver allowed a safe oncological resection of the tumor.展开更多
In acute ischemic stroke,collateral circulation plays an important role in maintaining blood flow to the tissue that is at risk of progressing into ischemia,and in increasing the successful recanalization rate without...In acute ischemic stroke,collateral circulation plays an important role in maintaining blood flow to the tissue that is at risk of progressing into ischemia,and in increasing the successful recanalization rate without hemorrhagic transformation.We have reported that well-developed collateral circulation is associated with smaller infarct volume and better long-term neurological outcome,and it disappears promptly once the effective recanalization is achieved.Contrary to the belief that collateral vessels develop over time in chronic stenotic condition,there exists a phenomenon that collateral circulation develops immediately in acute stenosis or occlusion of the arteries and it seems to be triggered by fluid shear stress,which occurs between the territories of stenotic/occluded arteries and those fed by surrounding intact arteries.We believe that this acute development of collateral circulation is a target of novel therapeutics in ischemic stroke and refer our recent attempt in enhancing collateral circulation by modulating sphingosine-1-phosphate receptor 1,which is a known shear-stress mechanosensing protein.展开更多
Objective To investigate therelationships between serum concentration of insulin -like growth factor - I (IGF-I) and left ventricular function as well as coronary collateral circulation in patients with coronary arter...Objective To investigate therelationships between serum concentration of insulin -like growth factor - I (IGF-I) and left ventricular function as well as coronary collateral circulation in patients with coronary artery disease (CAD) . Methods In 41 patients with CAD and 15 control subjects without CAD, the concentrations of serum IGF - I were measured using radioimmunoassay. The relationships between the concentration of serum IGF - I and Leaman coronary artery score, Rentrop grade of coronary collateral circulation, left ventricular ejection fraction (LVEF) as well as left ventricular wall motion Cortina score were assessed. Results 1. There was no significant difference in the mean level of serum IGF -I between the CAD group and the control group (107. 92±44.74 ng/ml vs 113.05 ±33. 65 ng/ml, P】 0. 05), but the IGF - I concentrations in the subgroup with collateral circulation were significantly greater than that in the control group (147. 33 ±29. 92 ng/ml vs 113. 05±33. 65 ng/ml, P 【 0. 01) or展开更多
Objective To determine the association of carotid plaque features with collateral circulation status in elderly patients with moderate to severe carotid stenosis.Methods Elderly patients(>60 years)with moderate to ...Objective To determine the association of carotid plaque features with collateral circulation status in elderly patients with moderate to severe carotid stenosis.Methods Elderly patients(>60 years)with moderate to severe carotid stenosis were recruited and categorized into good and poor collateral circulation groups,and underwent magnetic resonance imaging and computed tomography imaging.The carotid plaque features including lipid-rich necrotic core,intraplaque hemorrhage,calcification,and fibrous cap rupture(FCR)were evaluated,and maximum wall thickness,normalized wall index(NWI),and luminal stenosis were measured.The association between these variables and collateral circulation status was analyzed.Results Of the 97 patients(78 males,mean age:69.0±6.1 years),19(19.6%)had poor collaterals.The poor collateral group had a significantly higher NWI(93.7%±5.0%vs.89.0%±7.9%,P=0.011),a greater extent of stenosis(80.0%±11.4%vs.75.3%±9.4%,P=0.036)and FCR(84.2%vs.55.1%,P=0.020)compared with good collateral group.Carotid NWI(OR=3.83,95%CI:1.36–10.82,P=0.011)and more FCR(OR=6.77,95%CI:1.35–33.85,P=0.020)were associated with poor collateral circulation after adjustment for the confounding factors.The combination of NWI,FCR,systolic blood pressure,and triglycerides had the highest area-under-the-curve(AUC=0.85)for detection of poor collaterals.Conclusions Carotid plaque features,specifically NWI and FCR,are independently associated with poor collateral circulation,and the combination of carotid plaque features and traditional risk factors has a stronger predictive value for poor collateral circulation than plaque features alone.展开更多
Background: Coronary artery disease is highly prevalent in India with onset at a younger age. Coronary collateral circulation plays an important role in protecting myocardium from infarction, preserving myocardial con...Background: Coronary artery disease is highly prevalent in India with onset at a younger age. Coronary collateral circulation plays an important role in protecting myocardium from infarction, preserving myocardial contractility and reducing cardiovascular events. The objective of the present study is to assess the pattern of coronary collateral circulation in known cases of coronary artery disease with correlation to age, gender and degree of occlusion. Method: This is a retrospective study done on 200 preoperative angiograms in patients with coronary artery disease. Patients were classified according to age, gender and degree of obstruction in major vessels. Collateral vessels were graded according to the Rentrop classification. Patients with collaterals were further classified on the basis of intensity of collaterals into 3 groups: those with no collateralization (Grade 0), poor collateralization (Grade 1) and those with adequate collateralization (Grade 2 - 3). Results: Collateral development was seen in 175 (87.5%) angiograms. Collaterals were seen in 66% for left anterior descending (LAD), 44.5% for circumflex (LCx) and 70.5% for right coronary artery (RCA) block. Coronary collaterals between LAD and posterior descending artery (PDA) via ventricular septal branches were most common pathways. Adequate collaterals were seen in 53% males and 29.3% females (p 50 years and in 32% in cases with age p = 0.014) and 54.8% cases with arterial obstruction > 90%. Conclusion: Collateral circulation between LAD and PDA via ventricular septal branches is the commonest pathway to develop. Although prevalence of LAD occlusion is higher but collaterals develop more for RCA occlusion. Adequate collaterals develop more frequently in males, cases above 50 years and in vessels with >90% obstruction.展开更多
Objective To investigate the influences of previous angina pectoris on coronary collateral circulation and left ventricular function in patients with acute myocardial infarction. Methods 307 patients with a first epis...Objective To investigate the influences of previous angina pectoris on coronary collateral circulation and left ventricular function in patients with acute myocardial infarction. Methods 307 patients with a first episode acute myocardial infarction underwent selective coronary angiography and left ventriculography. The relation of previous angina pectoris to coronary collateral circulation, peak creatine kinase and left ventricular function were analyzed. Results ①In the 307 patients, there were 192 (62. 5 % ) with previous angina [PA (+) group] and 115 (37. 5 % ) without [PA (-) group].②The peak creatine kinase (CK) and CK MB were significantly higher in PA (-) group than in PA (+) group (P【0. 05 for both comparisons) . ③ Collateral circulation to infarct-related artery was more likely to be present in PA (+) group than in PA (-) group (P【0. 05) .④The left ventricular ejection fraction was significantly increased, and the left ventricular wall motion Cortina score decreased, in PA (+) group than展开更多
Objective To explore the value of quantitative parameters ofenhanced MRI inpredicting the establishment of inferior vena cava collateral circulation in patients with renal cell carcinoma and inferior vena cava tumor t...Objective To explore the value of quantitative parameters ofenhanced MRI inpredicting the establishment of inferior vena cava collateral circulation in patients with renal cell carcinoma and inferior vena cava tumor thrombus.展开更多
El Nino-Southern Oscillation(ENSO),the leading mode of global interannual variability,usually intensifies the Hadley Circulation(HC),and meanwhile constrains its meridional extension,leading to an equatorward movement...El Nino-Southern Oscillation(ENSO),the leading mode of global interannual variability,usually intensifies the Hadley Circulation(HC),and meanwhile constrains its meridional extension,leading to an equatorward movement of the jet system.Previous studies have investigated the response of HC to ENSO events using different reanalysis datasets and evaluated their capability in capturing the main features of ENSO-associated HC anomalies.However,these studies mainly focused on the global HC,represented by a zonal-mean mass stream function(MSF).Comparatively fewer studies have evaluated HC responses from a regional perspective,partly due to the prerequisite of the Stokes MSF,which prevents us from integrating a regional HC.In this study,we adopt a recently developed technique to construct the three-dimensional structure of HC and evaluate the capability of eight state-of-the-art reanalyses in reproducing the regional HC response to ENSO events.Results show that all eight reanalyses reproduce the spatial structure of HC responses well,with an intensified HC around the central-eastern Pacific but weakened circulations around the Indo-Pacific warm pool and tropical Atlantic.The spatial correlation coefficient of the three-dimensional HC anomalies among the different datasets is always larger than 0.93.However,these datasets may not capture the amplitudes of the HC responses well.This uncertainty is especially large for ENSO-associated equatorially asymmetric HC anomalies,with the maximum amplitude in Climate Forecast System Reanalysis(CFSR)being about 2.7 times the minimum value in the Twentieth Century Reanalysis(20CR).One should be careful when using reanalysis data to evaluate the intensity of ENSO-associated HC anomalies.展开更多
Lost circulation is a common downhole problem of drilling in geothermal and high-temperature,high-pressure(HTHP)formations.Lost circulation material(LCM)is a regular preventive and remedial measure for lost circulatio...Lost circulation is a common downhole problem of drilling in geothermal and high-temperature,high-pressure(HTHP)formations.Lost circulation material(LCM)is a regular preventive and remedial measure for lost circulation.However,conventional LCMs seem ineffective in high-temperature formations.This may be due to the changes in the mechanical properties of LCMs and their sealing performance under high-temperature conditions.To understand how high temperature affects the fracture sealing performance of LCMs,we developed a coupled computational fluid dynamics-discrete element method(CFD-DEM)model to simulate the behavior of granular LCMs in fractures.We summarized the literature on the effects of high temperature on the mechanical properties of LCMs and the rheological properties of drilling fluid.We conducted sensitivity analyses to investigate how changing LCM slurry properties affected the fracture sealing efficiency at increasing temperatures.The results show that high temperature reduces the size,strength,and friction coefficient of LCMs as well as the drilling fluid viscosity.Smaller,softer,and less frictional LCM particles have lower bridging probability and slower bridging initiation.Smaller particles tend to form dual-particle bridges rather than single-particle bridges.These result in a deeper,tighter,but unstable sealing zone.Reduced drilling fluid viscosity leads to faster and shallower sealing zones.展开更多
BACKGROUND:Unsustained return of spontaneous circulation(ROSC)is a critical barrier to survival in cardiac arrest patients.This study examined whether end-tidal carbon dioxide(ETCO_(2))and pulse oximetry photoplethysm...BACKGROUND:Unsustained return of spontaneous circulation(ROSC)is a critical barrier to survival in cardiac arrest patients.This study examined whether end-tidal carbon dioxide(ETCO_(2))and pulse oximetry photoplethysmogram(POP)parameters can be used to identify unsustained ROSC.METHODS:We conducted a multicenter observational prospective cohort study of consecutive patients with cardiac arrest from 2013 to 2014.Patients’general information,ETCO_(2),and POP parameters were collected and statistically analyzed.RESULTS:The included 105 ROSC episodes(from 80 cardiac arrest patients)comprised 51 sustained ROSC episodes and 54 unsustained ROSC episodes.The 24-hour survival rate was significantly higher in the sustained ROSC group than in the unsustained ROSC group(29.2%vs.9.4%,P<0.05).The logistic regression analysis showed that the difference between after and before ROSC in ETCO_(2)(ΔETCO_(2))and the difference between after and before ROCS in area under the curve of POP(ΔAUCp)were independently associated with sustained ROSC(odds ratio[OR]=0.931,95%confi dence interval[95%CI]0.881-0.984,P=0.011 and OR=0.998,95%CI 0.997-0.999,P<0.001).The area under the receiver operating characteristic curve ofΔETCO_(2),ΔAUCp,and the combination of both to predict unsustained ROSC were 0.752(95%CI 0.660-0.844),0.883(95%CI 0.818-0.948),and 0.902(95%CI 0.842-0.962),respectively.CONCLUSION:Patients with unsustained ROSC have a poor prognosis.The combination ofΔETCO_(2) andΔAUCp showed signifi cant predictive value for unsustained ROSC.展开更多
Aim: To explore the application effect of external diaphragm pacemaker combined with active respiratory circulation technology in pulmonary rehabilitation of perioperative lung cancer patients. Methods: A total of 98 ...Aim: To explore the application effect of external diaphragm pacemaker combined with active respiratory circulation technology in pulmonary rehabilitation of perioperative lung cancer patients. Methods: A total of 98 lung cancer patients admitted to our hospital from April 2020 to November 2021 were selected as the observation objects, and then divided into a control group and an observation group using the random number table method, with 49 cases in each group. The control group received routine admission guidance and active respiratory circulation training, while the observation group was supplemented with external diaphragm pacemaker on the basis of the control group. The intervention effect was evaluated by blood gas indicators, pulmonary function indicators, diaphragm function indicators, sputum comfort degree, and activity tolerance indicators before and after intervention. Results: Before intervention, there were no significant differences in blood gas analysis indicators, pulmonary function indicators, diaphragm function indicators, sputum comfort degree, and activity tolerance indicators between the two groups (P > 0.05). After intervention, the improvement degree of the above indicators in the observation group was higher than that in the control group (P < 0.05). Conclusions: The application of external diaphragm pacemaker combined with active respiratory circulation technology in pulmonary rehabilitation of perioperative lung cancer patients is significant, which can effectively improve the pulmonary function, blood gas function, and diaphragm function of lung cancer patients after surgery, and improve the activities of daily living and quality of life of patients.展开更多
Atlantic meridional overturning circulation(AMOC)plays an important role in transporting heat meridionally in the Earth’s climate system and is also a key metrical tool to verify oceanic general circulation models.Tw...Atlantic meridional overturning circulation(AMOC)plays an important role in transporting heat meridionally in the Earth’s climate system and is also a key metrical tool to verify oceanic general circulation models.Two OMIP(Ocean Model Intercomparison Project phase 1 and 2)simulations with LICOM3(version 3 of the LASG/IAP Climate System Ocean Model)developed at the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics(LASG),Institute of Atmospheric Physics(IAP),are compared in this study.Both simulations well reproduce the fundamental characteristics of the AMOC,but the OMIP1 simulation shows a significantly stronger AMOC than the OMIP2 simulation.Because the LICOM3 configurations are identical between these two experiments,any differences between them must be attributed to the surface forcing data.Further analysis suggests that sea surface salinity(SSS)differences should be mainly responsible for the enhanced AMOC in the OMIP1 simulation,but sea surface temperature(SST)also play an unignorable role in modulating AMOC.In the North Atlantic,where deep convection occurs,the SSS in OMIP1 is more saline than that in OMIP1.We find that in the major region of deep convection,the change of SSS has more significant effect on density than the change of SST.As a result,the SSS was more saline than that in OMIP2,leading to stronger deep convection and subsequently intensify the AMOC.We conduct a series of numerical experiments with LICOM3,and the results confirmed that the changes in SSS have more significant effect on the strength of AMOC than the changes in SST.展开更多
This is an erratum to an already published paper named“Establishment of a prediction model for prehospital return of spontaneous circulation in out-ofhospital patients with cardiac arrest”.We found errors in the aff...This is an erratum to an already published paper named“Establishment of a prediction model for prehospital return of spontaneous circulation in out-ofhospital patients with cardiac arrest”.We found errors in the affiliated institution of the authors.We apologize for our unintentional mistake.Please note,these changes do not affect our results.展开更多
This study investigates the relationship between circulation patterns and austral summer temperature anomalies in southern Africa. The results show that the formation of continental lows tends to increase the thicknes...This study investigates the relationship between circulation patterns and austral summer temperature anomalies in southern Africa. The results show that the formation of continental lows tends to increase the thickness of the lower atmosphere. Further, the distinct variabilities of high and low pressure under the circulation types, influence air mass advection from the adjacent oceans, as well as atmospheric stability over land. Stronger anticyclonic circulation at the western branch of the Mascarene high-pressure system enhances the low-level cold air advection by southeast winds,decreases the thickness, and lowers the temperature over a majority of the land in southern Africa. Conversely, a weaker Mascarene High, coupled with enhanced cyclonic activity in the southwest Indian Ocean increases low-level warm air advection and increases temperature anomalies over vast regions in southern Africa. The ridging of a closed South Atlantic anticyclone at the southern coast of southern Africa results in colder temperatures near the tip of southern Africa due to enhanced low-level cold air advection by southeast winds. However, when the ridge is weak and westerly winds dominate the southern coast of southern Africa, these areas experience temperature increases. The northward track of the Southern Hemisphere mid-latitude cyclone, which can be linked to the negative Southern Annular Mode, reduces the temperature in the southwestern part of southern Africa. Also, during the analysis period, El Ni?o was associated with temperature increases over the central parts of southern Africa;while the positive Indian Ocean dipole was linked to a temperature increase over the northeastern, northwestern, and southwestern parts of southern Africa.展开更多
文摘BACKGROUND The prognostic value of coronary collateral circulation(CC)in patients undergoing chronic total occlusion(CTO)percutaneous coronary intervention(PCI)is underdetermined.The purpose of the study was to assess the prognostic value of current two CC grading systems and their association with long-term outcomes in patients with CTO underwent PCI.METHODS We consecutively enrolled patients with single-vessel CTO underwent PCI between January 2010 and December2013.All patients were categorized into well-developed or poor-developed collaterals group according to angiographic Werner's CC(grade 2 vs.grade 0–1)or Rentrop(grade 3 vs.grade 0–2)grading system.The primary endpoint was 5-year cardiac death.RESULTS Of 2452 enrolled patients,the overall technical success rate was 74.1%.Well-developed collaterals were present in686 patients(28.0%)defined by Werner's CC grade 2,and in 1145 patients(46.7%)by Rentrop grade 3.According to Werner's CC grading system,patients with well-developed collaterals had a lower rate of 5-year cardiac death compared with those with poordeveloped collaterals(1.6%vs.3.3%,P=0.02),those with suboptimal recanalization was associated with higher rate of 5-year cardiac death compared with optimal recanalization(4.7%vs.0.8%,P=0.01)and failure patients(4.7%vs.1.6%,P=0.12).However,the similar effect was not shown in Rentrop grading system.CONCLUSIONS In patients with the single-vessel CTO underwent PCI,well-developed collaterals by Werner's CC definition were associated with lower rate of 5-year cardiac death.Werner's CC grading system had a greater prognostic value than Rentrop grading system in patients with CTO underwent PCI.
基金supported by the National Natural Science Foundation of China,No.81303021
文摘Acupuncture at Shuigou(GV26) shows good clinical efficacy for treating stroke, but its mechanism remains poorly understood. In this study, a cerebral infarction model of ischemia/reperfusion injury received electroacupuncture at GV26(15 Hz and 1 m A, continuous wave [biphasic pulses], for 5 minutes). Electroacupuncture effectively promoted regional cerebral blood flow on the infarct and non-infarct sides, increased infarct lesions, lectin, and number of blood vessels, upregulated von Willebrand factor and cell proliferation marker Ki67 expression, and diminished neurological severity score. These findings confirm that electroacupuncture at GV26 promotes establishment of collateral circulation and angiogenesis, and improves neurological function.
基金Supported by The Science Technology Program of Beijing Education Committee, No. KM200810025002
文摘AIM:To study characteristics of collateral circulation of gastric varices (GVs) with 64-row multidetector computer tomography portal venography (MDCTPV).METHODS:64-row MDCTPV with a slice thickness of 0.625 mm and a scanning field from 2 cm above the tracheal bifurcation to the lower edge of the kidney was performed in 86 patients with GVS diagnosed by endoscopy. The computed tomography protocol included unenhanced,arterial and portal vein phases. The MDCTPV was performed on an AW4.3 workstation. GVs were classified into three types according to Sarin's Classification. The afferent and efferent veins of each type of GV were observed.RESULTS:The afferent venous drainage originated mostly from the left gastric vein alone (LGV) (28/86,32.59%),or the LGV more than the posterior gastric vein/short gastric vein [LGV > posterior gastric vein/short gastric vein (PGV/SGV)] (22/86,25.58%),as seen by MDCTPV. The most common efferent venousdrainage was via the azygos vein to the superior vena cava (53/86,61.63%),or via the gastric/splenorenal shunt (37/86,43.02%) or inferior phrenic vein (8/86,9.30%) to the inferior vena cava. In patients with gastroesophageal varices type 1,the afferent venous drainage of GV mainly originated from the LGV or LGV > PGV/SGV (43/48,89.58%),and the efferent venous drainage was mainly via the azygos vein to the super vena cava (43/48,89.58%),as well as via the gastric/splenorenal shunt (8/48,16.67%) or inferior phrenic vein (3/48,6.25%) to the inferior vena cava. In patients with gastroesophageal varices type 2,the afferent venous drainage of the GV mostly came from the PGV/SGV more than the LGV (PGV/SGV > LGV) (8/16,50%),and the efferent venous drainage was via the azygos vein (10/16,62.50%) and gastric/splenorenal shunt (9/16,56.25%). In patients with isolated gastric varices,the main afferent venous drainage was via the PGV/SGV alone (16/22,72.73%),and the efferent venous drainage was mainly via the gastric/splenorenal shunt (20/22,90.91%),as well as the inferior phrenic vein (3/23) to the inferior vena cava. CONCLUSION:MDCTPV can clearly display the afferent and efferent veins of all types of GV,and it could provide useful reference information for the clinical management of GV bleeding.
基金Scientific Research Project of Guangdong Provincial Bureau of Traditional Chinese Medicine,NO.20212061Guangdong Province Basic and Applied Research Fund Project,NO.2020A1515110520.
文摘BACKGROUND Congenital coronary artery fistula can lead to symptoms of chest tightness,chest pain,or exertional dyspnea,which is a congenital vascular malformation that should not be ignored.Patients who have such malformations are frequently observed with different concurrent abnormal anatomic structures.Collateral circulation may have a positive effect on improving the patients'symptoms.CASE SUMMARY A 53-year-old female experienced episodic chest discomfort for the past month with symptoms manifesting when she was agitated or overexerted.After a positive treadmill test,the patient underwent coronary angiography.“Ghostlike”intermittent appearance of coronary ventricular fistula and collateral branching were observed.The patient was diagnosed with a right coronary ventricular fistula and collateral circulation.CONCLUSION This case shows the likelihood of collateral circulation in patients with coronary artery fistula.This may provide medical staff with novel solutions to treat insufficiency of myocardial blood supply induced by cardiovascular malformations.
基金supported by the Science Foundation of AMHT(2018-LCYL-009)the Medical and Health Research Project of China Aerospace Science and Industry Corporation Ltd.(KYLX-56).
文摘Background:Coronary collateral circulation(CCC)plays a vital role in the myocardial blood supply,especially for ischemic myocardium.Evidence suggests that the visfatin and 25-hydroxyvitamin D_(3)[25(OH)D_(3)]levels are related to the degree and incidence of vascular stenosis associated with coronary artery disease;however,few studies have evaluated the effect of visfatin and 25(OH)D_(3) on CCC development in patients with chronic total occlusion(CTO).This study aimed to evaluate the relationship between the serum visfatin and 25(OH)D_(3) levels and CCC in patients with CTO.Methods:A total of 189 patients with CTO confirmed by coronary angiography were included.CCC was graded from 0 to 3 according to the Rentrop-Cohen classification.Patients with grade 0 or grade 1 collateral development were in-cluded in the poor CCC group(n=82),whereas patients with grade 2 or grade 3 collateral development were included in the good CCC group(n=107).The serum visfatin and 25(OH)D_(3) levels were measured by ELISA.Results:The visfatin level was significantly higher in the poor CCC group than in the good CCC group,and the 25(OH)D_(3) level was significantly lower in the poor CCC group than in the good CCC group(P=0.000).Correlation analysis showed that the Rentrop grade was negatively correlated with the visfatin level(r=−0.692,P=0.000)but positively correlated with the 25(OH)D_(3) level(r=0.635,P=0.000).Logistic regression analysis showed that the vis-fatin and 25(OH)D_(3) levels were independent risk factors for CCC(odds ratio 1.597,95%confidence interval 1.300-1.961,P=0.000 and odds ratio 0.566,95%confidence interval 0.444-0.722,P=0.000,respectively).The visfatin and 25(OH)D_(3) levels can effectively predict the CCC status.Conclusion:Serum visfatin and 25(OH)D_(3) levels are related to CCC development and are independent predictors of poor CCC.
文摘BACKGROUND: Hepatobiliary cystadenocarcinoma represents a rare epithelial malignant tumor derived from the intrahepatic bile duct. METHODS: A 71-year-old woman, who had undergone laparoscopic drainage of a cystic lesion of the right hepatic lobe, was misdiagnosed as having hepatic echinococcal disease, and received intracystic infusion of 95% ethanol four years ago. She was admitted to our hospital for further treatment. RESULTS: Physical examination revealed dilated superficial veins across the right abdominal wall. After mapping the direction of blood flow in these vessels, we assumed that this was a sign of inferior vena cava obstruction. Abdominal ultrasound, computed tomography, magnetic resonance imaging combined with magnetic resonance angiography showed a large cystic mass in the right upper quadrant and epigastrium, displacing the adjacent structures, adherent to the inferior vena cava, which was not patent, resulting in dilation of superficial epigastric veins. The patient underwent an exploratory laparotomy. Total excision of the huge mass measuring 16×15 cm was possible under selective vascular exclusion of the liver. Removal of the tumor resulted in immediate restoration of flow in the inferior vena cava. On the basis of the pathology and findings of immunohistochemical analysis, a hepatobiliary cystadenocarcinoma was diagnosed.CONCLUSIONS: In the present case, hepatobiliary cystadenocar-cinoma was accompanied by dilated superficial venous collaterals due to inferior vena cava obstruction. Selective vascular exclusion of the liver allowed a safe oncological resection of the tumor.
文摘In acute ischemic stroke,collateral circulation plays an important role in maintaining blood flow to the tissue that is at risk of progressing into ischemia,and in increasing the successful recanalization rate without hemorrhagic transformation.We have reported that well-developed collateral circulation is associated with smaller infarct volume and better long-term neurological outcome,and it disappears promptly once the effective recanalization is achieved.Contrary to the belief that collateral vessels develop over time in chronic stenotic condition,there exists a phenomenon that collateral circulation develops immediately in acute stenosis or occlusion of the arteries and it seems to be triggered by fluid shear stress,which occurs between the territories of stenotic/occluded arteries and those fed by surrounding intact arteries.We believe that this acute development of collateral circulation is a target of novel therapeutics in ischemic stroke and refer our recent attempt in enhancing collateral circulation by modulating sphingosine-1-phosphate receptor 1,which is a known shear-stress mechanosensing protein.
文摘Objective To investigate therelationships between serum concentration of insulin -like growth factor - I (IGF-I) and left ventricular function as well as coronary collateral circulation in patients with coronary artery disease (CAD) . Methods In 41 patients with CAD and 15 control subjects without CAD, the concentrations of serum IGF - I were measured using radioimmunoassay. The relationships between the concentration of serum IGF - I and Leaman coronary artery score, Rentrop grade of coronary collateral circulation, left ventricular ejection fraction (LVEF) as well as left ventricular wall motion Cortina score were assessed. Results 1. There was no significant difference in the mean level of serum IGF -I between the CAD group and the control group (107. 92±44.74 ng/ml vs 113.05 ±33. 65 ng/ml, P】 0. 05), but the IGF - I concentrations in the subgroup with collateral circulation were significantly greater than that in the control group (147. 33 ±29. 92 ng/ml vs 113. 05±33. 65 ng/ml, P 【 0. 01) or
基金supported by the National Natural Science Foundation of China(No.81771825)Peking University Third Hospital(BYSY2015013)+1 种基金Beijing Municipal Science and Technology Commission(D171100003017003)Ministry of Science and Technology of China(2017 YFC1307904).
文摘Objective To determine the association of carotid plaque features with collateral circulation status in elderly patients with moderate to severe carotid stenosis.Methods Elderly patients(>60 years)with moderate to severe carotid stenosis were recruited and categorized into good and poor collateral circulation groups,and underwent magnetic resonance imaging and computed tomography imaging.The carotid plaque features including lipid-rich necrotic core,intraplaque hemorrhage,calcification,and fibrous cap rupture(FCR)were evaluated,and maximum wall thickness,normalized wall index(NWI),and luminal stenosis were measured.The association between these variables and collateral circulation status was analyzed.Results Of the 97 patients(78 males,mean age:69.0±6.1 years),19(19.6%)had poor collaterals.The poor collateral group had a significantly higher NWI(93.7%±5.0%vs.89.0%±7.9%,P=0.011),a greater extent of stenosis(80.0%±11.4%vs.75.3%±9.4%,P=0.036)and FCR(84.2%vs.55.1%,P=0.020)compared with good collateral group.Carotid NWI(OR=3.83,95%CI:1.36–10.82,P=0.011)and more FCR(OR=6.77,95%CI:1.35–33.85,P=0.020)were associated with poor collateral circulation after adjustment for the confounding factors.The combination of NWI,FCR,systolic blood pressure,and triglycerides had the highest area-under-the-curve(AUC=0.85)for detection of poor collaterals.Conclusions Carotid plaque features,specifically NWI and FCR,are independently associated with poor collateral circulation,and the combination of carotid plaque features and traditional risk factors has a stronger predictive value for poor collateral circulation than plaque features alone.
文摘Background: Coronary artery disease is highly prevalent in India with onset at a younger age. Coronary collateral circulation plays an important role in protecting myocardium from infarction, preserving myocardial contractility and reducing cardiovascular events. The objective of the present study is to assess the pattern of coronary collateral circulation in known cases of coronary artery disease with correlation to age, gender and degree of occlusion. Method: This is a retrospective study done on 200 preoperative angiograms in patients with coronary artery disease. Patients were classified according to age, gender and degree of obstruction in major vessels. Collateral vessels were graded according to the Rentrop classification. Patients with collaterals were further classified on the basis of intensity of collaterals into 3 groups: those with no collateralization (Grade 0), poor collateralization (Grade 1) and those with adequate collateralization (Grade 2 - 3). Results: Collateral development was seen in 175 (87.5%) angiograms. Collaterals were seen in 66% for left anterior descending (LAD), 44.5% for circumflex (LCx) and 70.5% for right coronary artery (RCA) block. Coronary collaterals between LAD and posterior descending artery (PDA) via ventricular septal branches were most common pathways. Adequate collaterals were seen in 53% males and 29.3% females (p 50 years and in 32% in cases with age p = 0.014) and 54.8% cases with arterial obstruction > 90%. Conclusion: Collateral circulation between LAD and PDA via ventricular septal branches is the commonest pathway to develop. Although prevalence of LAD occlusion is higher but collaterals develop more for RCA occlusion. Adequate collaterals develop more frequently in males, cases above 50 years and in vessels with >90% obstruction.
文摘Objective To investigate the influences of previous angina pectoris on coronary collateral circulation and left ventricular function in patients with acute myocardial infarction. Methods 307 patients with a first episode acute myocardial infarction underwent selective coronary angiography and left ventriculography. The relation of previous angina pectoris to coronary collateral circulation, peak creatine kinase and left ventricular function were analyzed. Results ①In the 307 patients, there were 192 (62. 5 % ) with previous angina [PA (+) group] and 115 (37. 5 % ) without [PA (-) group].②The peak creatine kinase (CK) and CK MB were significantly higher in PA (-) group than in PA (+) group (P【0. 05 for both comparisons) . ③ Collateral circulation to infarct-related artery was more likely to be present in PA (+) group than in PA (-) group (P【0. 05) .④The left ventricular ejection fraction was significantly increased, and the left ventricular wall motion Cortina score decreased, in PA (+) group than
文摘Objective To explore the value of quantitative parameters ofenhanced MRI inpredicting the establishment of inferior vena cava collateral circulation in patients with renal cell carcinoma and inferior vena cava tumor thrombus.
基金supported by the National Key Research and Development Program of China(Grant No.2018YFA0605703)the National Natural Science Foundation of China(Grant Nos.42176243,41976193 and 41676190)supported by National Natural Science Foundation of China(Grant No.41975079)。
文摘El Nino-Southern Oscillation(ENSO),the leading mode of global interannual variability,usually intensifies the Hadley Circulation(HC),and meanwhile constrains its meridional extension,leading to an equatorward movement of the jet system.Previous studies have investigated the response of HC to ENSO events using different reanalysis datasets and evaluated their capability in capturing the main features of ENSO-associated HC anomalies.However,these studies mainly focused on the global HC,represented by a zonal-mean mass stream function(MSF).Comparatively fewer studies have evaluated HC responses from a regional perspective,partly due to the prerequisite of the Stokes MSF,which prevents us from integrating a regional HC.In this study,we adopt a recently developed technique to construct the three-dimensional structure of HC and evaluate the capability of eight state-of-the-art reanalyses in reproducing the regional HC response to ENSO events.Results show that all eight reanalyses reproduce the spatial structure of HC responses well,with an intensified HC around the central-eastern Pacific but weakened circulations around the Indo-Pacific warm pool and tropical Atlantic.The spatial correlation coefficient of the three-dimensional HC anomalies among the different datasets is always larger than 0.93.However,these datasets may not capture the amplitudes of the HC responses well.This uncertainty is especially large for ENSO-associated equatorially asymmetric HC anomalies,with the maximum amplitude in Climate Forecast System Reanalysis(CFSR)being about 2.7 times the minimum value in the Twentieth Century Reanalysis(20CR).One should be careful when using reanalysis data to evaluate the intensity of ENSO-associated HC anomalies.
基金The authors gratefully acknowledge the financial support from the National Natural Science Foundation of China(Grant No.52274009)China Postdoctoral Science Foundation(Grant No.2022M723501)Science and Technology Planning Project of Sichuan Province(Grant No.2021YJ0359).
文摘Lost circulation is a common downhole problem of drilling in geothermal and high-temperature,high-pressure(HTHP)formations.Lost circulation material(LCM)is a regular preventive and remedial measure for lost circulation.However,conventional LCMs seem ineffective in high-temperature formations.This may be due to the changes in the mechanical properties of LCMs and their sealing performance under high-temperature conditions.To understand how high temperature affects the fracture sealing performance of LCMs,we developed a coupled computational fluid dynamics-discrete element method(CFD-DEM)model to simulate the behavior of granular LCMs in fractures.We summarized the literature on the effects of high temperature on the mechanical properties of LCMs and the rheological properties of drilling fluid.We conducted sensitivity analyses to investigate how changing LCM slurry properties affected the fracture sealing efficiency at increasing temperatures.The results show that high temperature reduces the size,strength,and friction coefficient of LCMs as well as the drilling fluid viscosity.Smaller,softer,and less frictional LCM particles have lower bridging probability and slower bridging initiation.Smaller particles tend to form dual-particle bridges rather than single-particle bridges.These result in a deeper,tighter,but unstable sealing zone.Reduced drilling fluid viscosity leads to faster and shallower sealing zones.
基金supported by National Natural Science Foundation of China General Program (82172179)Mathematics Tianyuan Fund (12126604)Central High-level Hospital Clinical Research Project (2022-PUMCH-B-110)
文摘BACKGROUND:Unsustained return of spontaneous circulation(ROSC)is a critical barrier to survival in cardiac arrest patients.This study examined whether end-tidal carbon dioxide(ETCO_(2))and pulse oximetry photoplethysmogram(POP)parameters can be used to identify unsustained ROSC.METHODS:We conducted a multicenter observational prospective cohort study of consecutive patients with cardiac arrest from 2013 to 2014.Patients’general information,ETCO_(2),and POP parameters were collected and statistically analyzed.RESULTS:The included 105 ROSC episodes(from 80 cardiac arrest patients)comprised 51 sustained ROSC episodes and 54 unsustained ROSC episodes.The 24-hour survival rate was significantly higher in the sustained ROSC group than in the unsustained ROSC group(29.2%vs.9.4%,P<0.05).The logistic regression analysis showed that the difference between after and before ROSC in ETCO_(2)(ΔETCO_(2))and the difference between after and before ROCS in area under the curve of POP(ΔAUCp)were independently associated with sustained ROSC(odds ratio[OR]=0.931,95%confi dence interval[95%CI]0.881-0.984,P=0.011 and OR=0.998,95%CI 0.997-0.999,P<0.001).The area under the receiver operating characteristic curve ofΔETCO_(2),ΔAUCp,and the combination of both to predict unsustained ROSC were 0.752(95%CI 0.660-0.844),0.883(95%CI 0.818-0.948),and 0.902(95%CI 0.842-0.962),respectively.CONCLUSION:Patients with unsustained ROSC have a poor prognosis.The combination ofΔETCO_(2) andΔAUCp showed signifi cant predictive value for unsustained ROSC.
文摘Aim: To explore the application effect of external diaphragm pacemaker combined with active respiratory circulation technology in pulmonary rehabilitation of perioperative lung cancer patients. Methods: A total of 98 lung cancer patients admitted to our hospital from April 2020 to November 2021 were selected as the observation objects, and then divided into a control group and an observation group using the random number table method, with 49 cases in each group. The control group received routine admission guidance and active respiratory circulation training, while the observation group was supplemented with external diaphragm pacemaker on the basis of the control group. The intervention effect was evaluated by blood gas indicators, pulmonary function indicators, diaphragm function indicators, sputum comfort degree, and activity tolerance indicators before and after intervention. Results: Before intervention, there were no significant differences in blood gas analysis indicators, pulmonary function indicators, diaphragm function indicators, sputum comfort degree, and activity tolerance indicators between the two groups (P > 0.05). After intervention, the improvement degree of the above indicators in the observation group was higher than that in the control group (P < 0.05). Conclusions: The application of external diaphragm pacemaker combined with active respiratory circulation technology in pulmonary rehabilitation of perioperative lung cancer patients is significant, which can effectively improve the pulmonary function, blood gas function, and diaphragm function of lung cancer patients after surgery, and improve the activities of daily living and quality of life of patients.
基金Supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA19060102)the National Natural Science Foundation of China(Nos.91958201,42130608)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB42000000)。
文摘Atlantic meridional overturning circulation(AMOC)plays an important role in transporting heat meridionally in the Earth’s climate system and is also a key metrical tool to verify oceanic general circulation models.Two OMIP(Ocean Model Intercomparison Project phase 1 and 2)simulations with LICOM3(version 3 of the LASG/IAP Climate System Ocean Model)developed at the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics(LASG),Institute of Atmospheric Physics(IAP),are compared in this study.Both simulations well reproduce the fundamental characteristics of the AMOC,but the OMIP1 simulation shows a significantly stronger AMOC than the OMIP2 simulation.Because the LICOM3 configurations are identical between these two experiments,any differences between them must be attributed to the surface forcing data.Further analysis suggests that sea surface salinity(SSS)differences should be mainly responsible for the enhanced AMOC in the OMIP1 simulation,but sea surface temperature(SST)also play an unignorable role in modulating AMOC.In the North Atlantic,where deep convection occurs,the SSS in OMIP1 is more saline than that in OMIP1.We find that in the major region of deep convection,the change of SSS has more significant effect on density than the change of SST.As a result,the SSS was more saline than that in OMIP2,leading to stronger deep convection and subsequently intensify the AMOC.We conduct a series of numerical experiments with LICOM3,and the results confirmed that the changes in SSS have more significant effect on the strength of AMOC than the changes in SST.
文摘This is an erratum to an already published paper named“Establishment of a prediction model for prehospital return of spontaneous circulation in out-ofhospital patients with cardiac arrest”.We found errors in the affiliated institution of the authors.We apologize for our unintentional mistake.Please note,these changes do not affect our results.
文摘This study investigates the relationship between circulation patterns and austral summer temperature anomalies in southern Africa. The results show that the formation of continental lows tends to increase the thickness of the lower atmosphere. Further, the distinct variabilities of high and low pressure under the circulation types, influence air mass advection from the adjacent oceans, as well as atmospheric stability over land. Stronger anticyclonic circulation at the western branch of the Mascarene high-pressure system enhances the low-level cold air advection by southeast winds,decreases the thickness, and lowers the temperature over a majority of the land in southern Africa. Conversely, a weaker Mascarene High, coupled with enhanced cyclonic activity in the southwest Indian Ocean increases low-level warm air advection and increases temperature anomalies over vast regions in southern Africa. The ridging of a closed South Atlantic anticyclone at the southern coast of southern Africa results in colder temperatures near the tip of southern Africa due to enhanced low-level cold air advection by southeast winds. However, when the ridge is weak and westerly winds dominate the southern coast of southern Africa, these areas experience temperature increases. The northward track of the Southern Hemisphere mid-latitude cyclone, which can be linked to the negative Southern Annular Mode, reduces the temperature in the southwestern part of southern Africa. Also, during the analysis period, El Ni?o was associated with temperature increases over the central parts of southern Africa;while the positive Indian Ocean dipole was linked to a temperature increase over the northeastern, northwestern, and southwestern parts of southern Africa.
