In situ staining of the primo vascular system in the ventricles and subarachnoid space of the brain by trypan blue injection into the lateral ventricle

We examined a new method for visualization of the primo vascular system in the rat brain involving lateral ventricle injection of trypan blue. Results showed that the primo vascular system in the lateral ventricles and arachnoid mater of the brain were preferentially stained relative to blood vessels and fascia. The primo-vessels along blood vessels in the brain were clearly exhibited. In addition, the primo vascular system was evident between the fourth ventricle and the quadrigeminal cistern. Our experimental findings indicate that this new technique of lateral ventricle injection of trypan blue can visualize the primo vascular system in lateral ventricles and arachnoid mater of rats in situ.

Concordant Atrioventricular Connection to L-Looped Ventricles with the Left Ventricle on Top of the Right Ventricle in Situs Solitus:A Case Report with 3D Modelling and Printing

We report the case of a rare complex cardiac anomaly involving situs solitus,concordant atrioventricular connection with left-hand ventricular topology,and L-looped ventricles.The ventricles had a superior-inferior relationship with an inferiorly located right ventricle,which had a double outlet with far posteriorly located great arteries.The left atrium was elongated,with juxta-positioned atrial appendages on the right side.The 3D-printed model using a computed tomography scan taken on the fourth day of birth demonstrated the anatomy clearly and helped us decide on the surgical management.

Modified distance regularized level set evolution for brain ventricles segmentation

Neurodegenerative disorders are commonly characterized by atrophy of the brain which is caused by neuronal loss.Ventricles are one of the prominent structures in the brain;their shape changes,due to their content,the cerebrospinal fluid.Analyzing the morphological changes of ventricles,aids in the diagnosis of atrophy,for which the region of interest needs to be separated from the background.This study presents a modified distance regularized level set evolution segmentation method,incorporating regional intensity information.The proposed method is implemented for segmenting ventricles from brain images for normal and atrophy subjects of magnetic resonance imaging and computed tomography images.Results of the proposed method were compared with ground truth images and produced sensitivity in the range of 65%–90%,specificity in the range of 98%–99%,and accuracy in the range of 95%–98%.Peak signal to noise ratio and structural similarity index were also used as performance measures for determining segmentation accuracy:95%and 0.95,respectively.The parameters of level set formulation vary for different datasets.An optimization procedure was followed to fine tune parameters.The proposed method was found to be efficient and robust against noisy images.The proposed method is adaptive and multimodal.

Prenatal Diagnosis of an Apically Located Congenital Left Ventricular Aneurysm: A Rare Case

Congenital ventricular aneurysm is a very rare cardiac anomaly.A diagnosis can be made during the prenatal period using fetal echocardiography.This study presents a very rare apically located left ventricular aneurysm case,and the relevant literature was reviewed and discussed.In this case,a 35-year-old,gravida 2,parity 1 preg-nant woman at 24 weeks of gestation,displayed a wide aneurysmal image in the left ventricular apical wall on fetal echocardiography.There was a 1.79 mm muscular ventricular septal defect at the apical region of the interven-tricular septum.In the course of the color Doppler ultrasonography examination,an aberrantfibrous band within the left ventricle and consequent turbulentflow during systole were observed.The baby,born via cesarean section at 37 weeks of gestation,is now in its postnatal seventh month.However,during echocardiographic follow-ups,changes have been observed,including mild to moderate mitral insufficiency and a decrease in systolic function.Despite thesefindings,the clinical condition remains asymptomatic.It is of great importance to use a multidis-ciplinary approach in managing these rare cases that could lead to potential adverse outcomes during the antena-tal or postnatal periods.

Double-chambered left ventricle with a thrombus in an asymptomatic patient:A case report

BACKGROUND Double-chambered left ventricle(DCLV)is an extremely rare congenital disease in which the left ventricle(LV)is divided by abnormal muscle tissue.Due to its rarity,there is a lack of data on the disease,including its diagnosis,treatment,and prognosis.Accordingly,we report a case in which DCLV was diagnosed and followed up.CASE SUMMARY A 45-year-old man presented to our hospital due to abnormal findings on an electrocardiogram recorded during a health check.He had no specific cardiac symptoms,comorbidities or relevant past medical history.Echocardiography revealed that the LV was divided into two by muscle fibers.There were no findings of ischemia on coronary angiography and coronary computed tomography angiography performed to exclude differential diagnoses.After comprehensive analysis of the images,DCLV was diagnosed.As it seemed to be asymptomatic DCLV,we decided the patient was to be observed without administering any medication.However,follow-up echocardiography revealed a thrombus in the accessory chamber(AC).Anticoagulant medication was initiated,the thrombus resolved,and the patient is currently undergoing follow-up without any specific symptoms.CONCLUSION Asymptomatic,uncomplicated DCLV was diagnosed through multimodal imaging;however,a thrombus in the AC occurred during the follow-up.The findings highlight that multimodal imaging is essential in diagnosing DCLV,and that anticoagulation is important in its management.

An Interpretable CNN for the Segmentation of the Left Ventricle in Cardiac MRI by Real-Time Visualization

The interpretability of deep learning models has emerged as a compelling area in artificial intelligence research.The safety criteria for medical imaging are highly stringent,and models are required for an explanation.However,existing convolutional neural network solutions for left ventricular segmentation are viewed in terms of inputs and outputs.Thus,the interpretability of CNNs has come into the spotlight.Since medical imaging data are limited,many methods to fine-tune medical imaging models that are popular in transfer models have been built using massive public Image Net datasets by the transfer learning method.Unfortunately,this generates many unreliable parameters and makes it difficult to generate plausible explanations from these models.In this study,we trained from scratch rather than relying on transfer learning,creating a novel interpretable approach for autonomously segmenting the left ventricle with a cardiac MRI.Our enhanced GPU training system implemented interpretable global average pooling for graphics using deep learning.The deep learning tasks were simplified.Simplification included data management,neural network architecture,and training.Our system monitored and analyzed the gradient changes of different layers with dynamic visualizations in real-time and selected the optimal deployment model.Our results demonstrated that the proposed method was feasible and efficient:the Dice coefficient reached 94.48%,and the accuracy reached 99.7%.It was found that no current transfer learning models could perform comparably to the ImageNet transfer learning architectures.This model is lightweight and more convenient to deploy on mobile devices than transfer learning models.

Notice of Retraction

Retraction:Ultrasound guided neural stem cell transplantation through the lateral ventricle for treatment of cerebral palsy in children https://doi.org/10.4103/1673-5374.346552 The Editors of Neural Regeneration Research(NRR)h a s ret ra c te d t h e p u b l i cat i on entitled“Ultrasound guided neural stem cell transplantation through the lateral ventricle for treatment of cerebral palsy in children”(He et al.,2012;doi:10.3969/j.issn.1673-5374.2012.32.007)following the concerns of duplicate publication according to NRR Policy on Article Retraction(https://journals.lww.com/nrronline/Pages/instructionsforauthors.aspx).

Long-Term Outcomes of Systemic-to-Pulmonary Artery Shunt in Patients with Functional Single Ventricle and Heterotaxy Syndrome

Objectives: We sought to determine the long-term outcomes and mortality-associated factors after systemic-topulmonaryartery shunt (SPS) in patients with heterotaxy syndrome. Methods: We retrospectively analyzed allpatients with a functional single ventricle and heterotaxy syndrome who underwent SPS at our center from January2001 to April 2022. Results: This study involved 84 patients. Restrictive pulmonary blood flow requiringearly modulation was presented in 34 (40%) patients. Compared with patients without restrictive pulmonaryblood flow (N = 50 [60%]), the postnatal survival of these 34 patients was significantly lower at 10 years (log rank:p = 0.04), but the statistical significance disappeared at 20 years (log rank: p = 0.18). Among 31 patients whounderwent SPS, 11 (35%) had extracardiac total anomalous pulmonary venous connection (TAPVC). The survivalrate after SPS was 80% at 10 years. Cox regression analysis showed that extracardiac TAPVC (hazard ratio6.44, 95% confidence interval 1.23–33.7, p = 0.03) and pulmonary venous obstruction (PVO) at TAPVC repair(hazard ratio 11.2, 95% confidence interval 2.13–58.5, p = 0.004) were significantly associated with death. In25 patients who underwent bidirectional cavopulmonary shunt (BCPS), surgical interventions on the pulmonaryartery (PA) were performed after SPS in 7 of 9 patients with PA coarctation, 3 of 4 with non-confluent PAs, and4 of 12 with normal PAs. At SPS, primary central PA plasty was performed in three patients with PA coarctationand 2 with non-confluent PAs. There was no significant difference in the PA index before BCPS between patientswith and without primary central PA plasty (p = 0.49). Among 20 patients who underwent total cavopulmonaryconnection (TCPC), adverse events occurred in 7 (35%) patients, including death in 1 (5%), intervention for pulmonaryarteriovenous malformation (PAVM) in 3 (15%), and surgical intervention for PVO in 3 (15%). TheB-type natriuretic peptide concentration was significantly higher in patients with than without adverse events(p = 0.02). The adverse event-free survival rate after TCPC was 69% at 10 years. Conclusion: ExtracardiacTAPVC and PVO at TAPVC repair were significantly associated with death after SPS in patients who had heterotaxysyndrome with a single ventricle. Surgical interventions on the PA were frequently required after SPS inpatients with PA coarctation or non-confluent PAs. Although satisfactory survival was achievable after TCPC,late-onset PAVM and PVO remain concerns.

Detection of Left Ventricular Cavity from Cardiac MRI Images Using Faster R-CNN

The automatic localization of the left ventricle(LV)in short-axis magnetic resonance(MR)images is a required step to process cardiac images using convolutional neural networks for the extraction of a region of interest(ROI).The precise extraction of the LV’s ROI from cardiac MRI images is crucial for detecting heart disorders via cardiac segmentation or registration.Nevertheless,this task appears to be intricate due to the diversities in the size and shape of the LV and the scattering of surrounding tissues across different slices.Thus,this study proposed a region-based convolutional network(Faster R-CNN)for the LV localization from short-axis cardiac MRI images using a region proposal network(RPN)integrated with deep feature classification and regression.Themodel was trained using images with corresponding bounding boxes(labels)around the LV,and various experiments were applied to select the appropriate layers and set the suitable hyper-parameters.The experimental findings showthat the proposed modelwas adequate,with accuracy,precision,recall,and F1 score values of 0.91,0.94,0.95,and 0.95,respectively.This model also allows the cropping of the detected area of LV,which is vital in reducing the computational cost and time during segmentation and classification procedures.Therefore,itwould be an ideal model and clinically applicable for diagnosing cardiac diseases.

Right ventricle dysfunction does not predict mortality in patients with SARS-CoV-2-related acute respiratory distress syndrome on extracorporeal membrane oxygenation support

BACKGROUND The prognostic role of right ventricle dilatation and dysfunction(RVDD)has not been elucidated in patients with coronavirus disease(COVID)-related respiratory failure refractory to standard treatment needing extracorporeal membrane oxygenation(ECMO)support.AIM To assess whether pre veno-venous(VV)ECMO RVDD were related to inintensive care unit(ICU)mortality.METHODS We enrolled 61 patients with COVID-related acute respiratory distress syndrome refractory to conventional treatment submitted to VV ECMO and consecutively admitted to our ICU(an ECMO referral center)from 31th March 2020 to 31th August 2021.An echocardiographic exam was performed immediately before VV ECMO implantation.RESULTS Males were prevalent(73.8%)and patients with a body mass index>30 kg/m^(2) were the majority(46/61,75%).The overall in-ICU mortality rate was 54.1%(33/61).RVDD was detectable in more than half of the population(34/61,55.7%)and associated with higher simplified organ functional assessment(SOFA)values(P=0.029)and a longer mechanical ventilation duration prior to ECMO support(P=0.046).Renal replacement therapy was more frequently needed in RVDD patients(P=0.002).A higher in-ICU mortality(P=0.024)was observed in RVDD patients.No echo variables were independent predictors of in-ICU death.CONCLUSION In patients with COVID-related respiratory failure on ECMO support,RVDD(dilatation and dysfunction)is a common finding and identifies a subset of patients characterized by a more severe disease(as indicated by higher SOFA values and need of renal replacement therapy)and by a higher in-ICU mortality.RVDD(also when considered separately)did not result independently associated with in-ICU mortality in these patients.

Systemic right ventricle complications in levo-transposition of the great arteries: A case report and review of literature

BACKGROUND Congenitally corrected levo-transposition of the great arteries(L-TGA)is a congenital heart disease in which the ventricles and great arteries are transposed from their typical anatomy.In L-TGA,the double discordance,atrioventricular and ventriculoarterial,create an acyanotic milieu which allows patients to survive their early decades,however,progressive systemic right ventricle(sRV)dys-function creates complications later in life.sRV dysfunction and remodeling predisposes patients to intracardiac thrombus(ICT)formation.CASE SUMMARY A 40-year-old male with L-TGA presented with symptoms of acute decom-pensated heart failure.In childhood,he had surgical repair of a ventricular septal defect.In adulthood,he developed sRV dysfunction,systemic tricuspid valve(sTV)regurgitation,and left-bundle branch block for which he underwent cardiac resynchronization therapy.Transthoracic echocardiogram showed a sRV ejection fraction of 40%,severe sTV regurgitation,and a newly identified sRV ICT.ICT was confirmed by ultrasound-enhancing agents and transesophageal echocardio-graphy.Our patient was optimized with guideline-directed medical therapy and diuresis.Anticoagulation was achieved with a vitamin K antagonist(VKA)and he was later referred for evaluation by advanced heart failure and heart transplant services.CONCLUSION Anticoagulation with VKA is the mainstay of treatment in the absence of conclusive data supporting direct oral anticoagulant use in ICT in patients with congenital heart disease.This case illustrates the natural history of L-TGA and highlights the importance of surveillance and monitoring with dedicated cardiac imaging to identify complications.

Value of clinical applications of differential pressure and relative pressure imaging in the left ventricle

Regional pressure differences between sites within the left ventricular cavity have long been identified,and the potential clinical value of diastolic and systolic intraventricular pressure differences(IVPDs)is of increasing interest.This study concluded that the IVPD plays an important role in ventricular filling and emptying and is a reliable indicator of ventricular relaxation,elastic recoil,diastolic pumping,and effective left ventricular filling.Relative pressure imaging,as a novel and potentially clinically applicable measure of left IVPDs,enables early and more comprehensive identification of the temporal and spatial characteristics of IVPD.In the future,as research related to relative pressure imaging continues,this measurement method has the possibility to become more refined and serve as an additional clinical aid that can replace the gold standard cardiac catheterization technique for the diagnosis of diastolic dysfunction.

Isolated left ventricular apical hypoplasia:Systematic review and analysis of the 37 cases reported so far

BACKGROUND Isolated left ventricular apical hypoplasia(ILVAH),also known as truncated left ventricle(LV),is a very unusual cardiomyopathy.It is characterised by a truncated,spherical,and non-apex forming LV.The true apex is occupied by the right ventricle.Due to the rarity of the disease,just a few case reports and limited case series have been published in the field.AIM To analysing the so far 37 reported ILVAH cases worldwide.METHODS The electronic databases PubMed and Scopus were investigated from their establishment up to December 13,2022.RESULTS The majority of cases reported occurred in males(52.7%).Mean age at diagnosis was 26.1±19.6 years.More than a third of the patients were asymptomatic(35.1%).The most usual clinical presentation was breathlessness(40.5%).The most commonly detected electrocardiogram changes were T wave abnormalities(29.7%)and right axis deviation with poor R wave progression(24.3%).Atrial fibrillation/flutter was detected in 24.3%.Echocardiography was performed in 97.3%of cases and cardiac MRI in 91.9%of cases.Ejection fraction was reduced in more than a half of patients(56.7%).An associated congenital heart disease was found in 16.2%.Heart failure therapy was administered in 35.1%of patients.The outcome was favorable in the vast majority of patients,with just one death.CONCLUSION ILVAH is a multifaceted entity with a so far unpredictable course,ranging from benign until the elderly to sudden death during adolescence.

Inadvertent Lead Malposition in the Left Ventricle during Permanent Ventricular Pacing about One Case

Inadvertent Lead Malposition in Left Ventricle is a rare and underdiagnosed incident, which may occur during implantation of cardiac electronic devices and may remain asymptomatic. We reported the case of a 71-year-old man who was implanted with a ventricular single-chamber pacemaker for a slow atrial fibrillation with syncope and whose routine transthoracic echocardiography 23 months after implantation displayed a malposition of the pacemaker lead into the Left Ventricle through a patent foramen oval. The patient was asymptomatic. The electrocardiogram showed right bundle branch block QRS-paced morphology with a positive QRS pattern in V1, a median paced QRS axis on the frontal plane at -120°, a Precordial transition on V5. At the lateral Chest X-ray the lead curved backwards to the spine. Given the age of this old patient who already received oral anticoagulant for Atrial Fibrillation and the Lead malposition discovered 23 months after pacemaker’s implantation, we decided to maintain the lead in LV and continue anticoagulation.

Effect of Purified Paper Wasp Ropalidia marginata Venom Toxin Enzyme Activity in Blood Serum, Liver, and Gastrocnemius Muscle of Albino Mice

In the present, investigation effects of sub-lethal dose of purified paper wasp Ropalidia marginata venom toxins were evaluated on important metabolic enzymes i.e. ALP ACP, GPT, GOT, LDH, and AchE enzyme activity in serum, liver, and gastrocnemius muscles of albino mice. Alkaline phosphatase was found to be increased up to 119.9% at the 6th hr of the toxin injection in comparison to control. This elevation may be due to cytolysis. Maximum increase i.e., 153.33% level of glutamate pyruvate transaminase (GPT) was found at 6 hrs of 40% of 24-h LD50 treatment while it was found to be 151.1% at 6 hrs of 24 hr 80% of LD50, venom injection. A significant elevation was observed in LDH activity in serum, liver, and muscles, while the activity of AchE was decreased in serum, liver, and gastrocnemius muscles of albino mice after injecting the sub-lethal dose of Ropalidia marginata venom. This increase in the activity of LDH produces liver damage, massive disintegration and necrosis of hepatic cells. This elevation in LDH level led to a significant increase in the glucose catabolism and elevated oxidative stress in muscle and liver cells. It also displays insufficient oxygen supply and consequently leads to cell death. In experimental animals, venom toxin treatment decreased AchE level, and animals showed muscular paralysis. When mice were treated with 40% and 80% of 24-h LD50 of purified venom caused a significant (p < 0.05) elevation in the level of ACP, GOT, GPT, and LDH while the reduction in ALP and AChE level. Present study will be useful in the development of prototypes for study of pharmacological and therapeutic effects of various venom toxins. For this purpose structure activity relationship of enzyme and venom toxin, its due interaction to various metabolic enzymes and receptors must be explored.

Effects of Purified Indian Cattle Tick Rhipicephalus microplus Saliva Toxins on Various Enzymes in Blood Serum, Liver and Muscles of Albino Mice

In the present investigation, in vivo effects of purified ticks’ saliva toxin were evaluated on the level of certain important cellular metabolic enzymes i.e. acid phosphatase (ACP), alkaline phosphatase (ALP), glutamate pyruvate transaminase, glutamate oxaloacetate transaminase and lactic dehydrogenase. For this purpose, sub-lethal doses, 40% and 80% of 24 h LD50 purified saliva toxins of Rhipicephalus microplus (Canestrini, 1888) were injected subcutaneously in the albino mice. In treated mice saliva toxins targeted membrane-bound enzymes i.e. serum acid phosphatase and alkaline phosphatase, its level was increased from 118.30% to 163.63% at the 6th hr in comparison to the control. Besides this, the levels of serum glutamate pyruvate transaminase (GPT) and glutamate oxaloacetate transaminase (GOT) and lactic dehydrogenase (LDH) also increased up to 161.11% (at 6th hr), 148.27 (at 8th hr) and 125.45% (at 6th hr) respectively in comparison to control. An increase in the level of LDH showed insufficient oxygen supply, massive disintegration of cells and leakage of the enzyme into the circulation. It clearly indicated the toxic effects of saliva toxins on the membrane of blood cells, hepatocytes and myocardial muscle cell functions in albino mice. On the other hand activity of acetyl cholinesterase was reduced by 65.51% at the 6th hr of the saliva toxin injection in comparison to the control. This inhibition of acetyl cholinesterase activity caused the accumulation of acetylcholine molecules at the synaptic junctions and led to prolonged activation of acetylcholine receptors. It caused permanent stimulation of nerves and muscle cells that may result in muscular paralysis and finally death of the animal.

Proposed Simple, Efficient Free Hand Technique for Frontal External Ventricular Drain (EVD) in Case of Small Ventricle: A Report of New Technique

Background: EVD is a common procedure done in neurosurgery and the residents should master it and this is what exactly means that it should be simple, safe, fast and accurate. EVD can be done through many entry points to the different part of the lateral ventricle but the famous site is the anterior horn of the lateral ventricle which is commonly approached through Kocher’s point which is a famous point for all neurosurgeon by its measurements of allocation. The commonest problem with EVD insertion into the anterior horn is the navigation of the ventricular cavity with the right trajectory and so the location of the catheter tip in the right place near the foramen of monro to ensure CSF draining. Size of the ventricle plays significant role in the success of the procedure especially free hand technique. The more dilated ventricle, the more chance to hit the ventricular cavity especially from the first trial and vice versa. In case of small ventricle, the procedure with free hand technique seems more complicated and the chance to hit the ventricle from the first trial may reduce especially with non-expert surgeon but may succeed in the following trials with increased risk of complications with more trials. Purpose: Most EVD’s are placed with freehand technique which depends on the operator skills to navigate the ventricle with right trajectory and hit the ventricle from the first trial, because many trials may complicate the procedure and produce undesirable side effects. So the key in this free hand technique is how to ensure the success from the first trial. In case of small anterior horn of the lateral ventricle, the procedure is even more difficult with the free hand technique and the classic Kocher point needs an expert to get the right trajectory to navigate such small ventricle. Our point idea came from this prospective and aimed at raising the success of the procedure especially in the first attempt with simple technique. Method: It is a new entry point for EVD insertion through frontal burr hole gained by the intersection of two lines: the first is running vertically from the ipsilateral medial canthus downward and the second is running horizontal along the coronal suture which is usually palpable as ridge on the scalp extended lateral from the bregma. Burr hole is done just anterior to this intersection and catheter is placed in a perpendicular trajectory toward the ventricular cavity. Result: It has been used in about (n = 50 cases) fulfilling the criteria of radiological small ventricle as defined and they were candidates for EVD insertion by free hand technique. Only 3 cases (6%) out of the 50 cases failed in the first attempt but succeeded in the following trial. So high rate of success in first trial is seen in the most of cases using this technique during a period of one year of our practice without significant side effects seen. Conclusion: Our study is not conclusive and needs further studies for more evaluation. It was a suggested point other than the classic Kocher point in case of free hand EVD insertion in small ventricle. We recommend to try it and report any advantages or disadvantages to the literature.

房室连接不一致右心室双出口根治手术的选择与适应证优化

目的 回顾性分析房室连接不一致右心室双出口(doubleoutlet right ventricle,DORV)的病理解剖特点、手术方法选择和治疗结果,探讨手术适应证和手术方法的优化。 方法 1990年9月至2 0 0 4年8月对7例房室连接不一致的DORV患者施行根治手术治疗,年龄3～7岁,其中形态学左心室与肺动脉心外管道连接和室间隔缺损修补术3例,double- switch(双调转)手术2例,改良Fontan手术2例。 结果 手术早期死亡1例(14 .3% ,1/ 7) ,为手术后2个月并发Hom ograft感染。 度房室传导阻滞1例,安装永久心外膜起搏器;1例改良Fontan手术后并发上腔静脉回流梗阻和心包积液,症状改善后出院。Double- switch手术后平均监护时间最短为术后6 d。 结论 房室连接不一致DORV根治手术应首选double- switch手术,尤其对形态学右心室功能不全和三尖瓣关闭不全者,如果合并多种复杂畸形解剖无法矫治,可选择单个心室的修补方案。

血浆脑钠素水平与心衰患者左心功能关系的探讨

目的:为探讨血浆脑钠素(BNP)水平与心力衰竭患者临床心功能变化之间的关系。方法:本文采用IRMA测定患者血浆BNP水平,同时采用NYHA心功能分级和超声心动图检查评定患者左心功能。结果:随着心功能恶化,血浆BNP水平呈上升趋势。各级心功能间差异均有显著性临床意义(P<0.05)。经抗心衰药物综合治疗后,BNP水平降低(P<0.01)。BNP水平与左心室射血分数(LVEF)、左心室短轴缩短率(D%,D即leftventriclefractionshortening)呈负相关;与左室收缩末内径(LVSd)、左室舒张末内径(LVDd)呈正相关。结论:在患者心力衰竭的进展中其血浆中BNP水平与心衰程度密切相关,测定患者血浆BNP水平是监测心衰程度的有效手段之一。