Prior expectation enhances sensorimotor behavior by modulating population tuning and subspace activity in sensory cortex.

Prior knowledge facilitates our perception and goal-directed behaviors, particularly when sensory input is lacking or noisy. However, the neural mechanisms underlying the improvement in sensorimotor behavior by prior expectations remain unknown. In this study, we examine the neural activity in the middle temporal (MT) area of visual cortex while monkeys perform a smooth pursuit eye movement task with prior expectation of the visual target's motion direction. Prior expectations discriminately reduce the MT neural responses depending on their preferred directions, when the sensory evidence is weak. This response reduction effectively sharpens neural population direction tuning. Simulations with a realistic MT population demonstrate that sharpening the tuning can explain the biases and variabilities in smooth pursuit, suggesting that neural computations in the sensory area alone can underpin the integration of prior knowledge and sensory evidence. State-space analysis further supports this by revealing neural signals of prior expectations in the MT population activity that correlate with behavioral changes.

Multivariate EEG activity reflects the Bayesian integration and the integrated Galilean relative velocity of sensory motion during sensorimotor behavior.

Humans integrate multiple sources of information for action-taking, using the reliability of each source to allocate weight to the data. This reliability-weighted information integration is a crucial property of Bayesian inference. In this study, participants were asked to perform a smooth pursuit eye movement task in which we independently manipulated the reliability of pursuit target motion and the direction-of-motion cue. Through an analysis of pursuit initiation and multivariate electroencephalography activity, we found neural and behavioral evidence of Bayesian information integration: more attraction toward the cue direction was generated when the target motion was weak and unreliable. Furthermore, using mathematical modeling, we found that the neural signature of Bayesian information integration had extra-retinal origins, although most of the multivariate electroencephalography activity patterns during pursuit were best correlated with the retinal velocity errors accumulated over time. Our results demonstrated neural implementation of Bayesian inference in human oculomotor behavior.

Proposal of Construction Method of Smart Liner to Block and Detect Spreading of Soil Contaminants by Oil Spill.

Soil is an important factor for public health, and when a soil contaminant occurs by oil spill, it has a great impact on the ecosystem, including humans. Accordingly, the area is blocked using a vertical barrier, and various remediation methods are being applied when an oil spill occurs. This study intends to use a smart liner to prevent and detect the spreading of soil contaminants in a situation in which oil spill detection is important. However, the smart liner is in the form of a fiber, so it is impossible to construct it in a general method. Therefore, the roll spreading and inserting method (RSIM) is proposed for smart liner construction. RSIM is a method of installing a supporting pile after excavating the ground and connecting the smart liner vertically to the ground surface. This method is the first method proposed in this study, and the design and concept have not been established. In this study, a conceptual design was established to apply RSIM in the actual field, and a scale model experiment was performed to prove it. As a result of the scale model experiment, the applicability of RSIM was confirmed. Finally, numerical analysis using Abaqus/CAE was performed to carry out the detailed design of RSIM (installation conditions such as dimensions). Analysis parameters were embedded depth, thickness, diameter, and material properties of a supporting pile according to the ground type. As a result of the analysis, it was confirmed that the results of RSIM analysis were interacting with all parameters according to the ground conditions. Therefore, it was confirmed that the actual design should be based on ground investigation and economic conditions, not standardized regulations.

Numerical Analysis of Factors Influencing the Ground Surface Settlement above a Cavity.

In this study, ground stability was evaluated through vertical displacement distribution and surface settlement results. In particular, a finite element analysis was conducted considering various factors (namely, cavity type and area, traffic load, pavement thickness, and elastic modulus) that affect a road above a cavity. The aim of this study was to evaluate the effect of pavement layer and traffic load condition on surface settlement according to the cavity shape. Field measurement results were analyzed and compared with the results of previous studies to verify the reliability of the numerical analysis method applied herein. After performing the numerical analysis using the verified method, ground stability was evaluated by analyzing the underground mechanical behavior of a road above a cavity. To this end, the correlations among the vertical displacement distribution, surface settlement, and influencing factors obtained from the analysis results were analyzed. In the numerical analysis, the ground was simulated with a hardening soil model based on the elastoplastic theory. This mechanical soil model can accurately reproduce the behavior of actual ground and can closely represent the mechanical behavior of the soil surrounding a cavity according to the cavity generation. In addition, the elapsed time was not considered when applying a load on the pavement layer, and a uniformly distributed load was applied. Consequently, it was found that, with increasing cavity area and traffic load and decreasing pavement thickness and elastic modulus, the vertical displacement and maximum surface settlement above the cavity increased, and the reduction in ground stability was greater. Furthermore, the reduction in ground stability was greater when the cavity was rectangular than when it was circular.

Simulation on the Permeability Evaluation of a Hybrid Liner for the Prevention of Contaminant Diffusion in Soils Contaminated with Total Petroleum Hydrocarbon.

This study describes the test results to evaluate the impermeability efficiency, according to the total petroleum hydrocarbon (TPH) reaction time of a hybrid liner for preventing the TPH diffusion, and the numerical analysis results, according to the various TPH reaction times of the hybrid liner. The experimental results indicated that the hybrid liner performed effectively as an impermeable material under the condition of a 4 h reaction time between TPH and the hybrid liner. In other words, the permeability of the hybrid liner was lower than 7.64 × 10-7 cm/s when the reaction time of the TPH and the hybrid liner exceeded 4 h. This means that polynorbornene applied as a reactant becomes completely gelated four hours after it reacts with TPH, demonstrating its applicability as a liner. The numerical analysis results to evaluate the TPH diffusion, according to the hybrid liner-TPH reaction time indicated that the concentration decreased, compared to the initial concentration as the hybrid liner-TPH reaction time increased, regardless of the head-difference and the observation point for all concentration conditions. In addition, the reduction ratio of the concentration, compared to the initial concentration was 99% ~ 100%, when the reaction time of the hybrid liner-TPH was more than 4 h. It was found that the concentration diffusion of TPH reacting with the hybrid liner was decreased when the distance from the hybrid liner and the reaction time of the hybrid liner-TPH were increased. In other words, in the case of a high-TPH condition, the concentration reduction ratio is 12.5~17.8%, 16.9~29.7%, depending on the distance ratio (D/L = 0.06, 0.54, 0.94), respectively, when the reaction time of the hybrid liner-TPH is 0 h and 0.5 h, respectively. In the case of medium- and low-TPH conditions, the concentration reduction ratio, according to the distance ratio is 12.0% to 20.8% and 17.0% to 29.8%, respectively. This result means that a numerical analysis model can be used sufficiently to predict the TPH diffusion, according to the distance from the location where the hybrid liner is installed.

Clinical Outcomes and Effectiveness of Heart Transplantation in Patients With Systemic Light-chain Cardiac Amyloidosis.

BACKGROUND: In systemic light-chain (AL) amyloidosis, cardiac involvement is a major determinant of survival; however, cardiac response is limited even after systemic treatment in a majority of patients, and some require heart transplantation. Additionally, limited information is available on specific indications for heart transplantation. We aimed to explore clinical outcomes of cardiac amyloidosis and its association with heart transplantation, including identifying factors favoring heart transplantation amenability. METHODS: We retrospectively analyzed data from patients diagnosed with AL amyloidosis with cardiac involvement between January 2007 and December 2020 at a tertiary referral center. RESULTS: Among 73 patients, 72 (99%) received systemic treatment, and 12 (16%) underwent heart transplantation. Characteristics at diagnosis were similar between heart transplant recipients and nonrecipients, although left ventricular ejection fraction tended to be lower in recipients (median 48% versus 57%, P = 0.085). Eight weeks after systemic treatment, 67% and 12% of patients achieved hematologic and brain natriuretic peptide responses. Overall survival was longer among heart transplantation recipients than nonrecipients, with 5-y survival rates of 61.1% (95% confidence interval, 25.5%-83.8%) versus 32.0% (95% confidence interval, 20.3%-44.4%; P = 0.022), respectively. Among the 34 with identifiable causes of death out of 51 deaths, 21 nonrecipients (62%) died of cardiac problems compared with none in the heart transplant recipients. Additionally, survival outcomes favored heart transplant recipients in most subgroups, including patients with higher Mayo 2004 European stage at diagnosis and with extracardiac involvement of amyloidosis. CONCLUSIONS: Heart transplantation can achieve long-term survival in appropriately selected patients with AL cardiac amyloidosis.

Effective Length Prediction and Pullout Design of Geosynthetic Strips Based on Pullout Resistance.

In this study, pullout tests were conducted on geosynthetic strips which can be applied to a block-type front wall. Based on the test results, the effective length is predicted, and the pullout design results are presented. In other words, the pullout displacement-pullout load relationship of all geosynthetic strips was analyzed using the pullout test results, and their effective lengths were predicted. It was found that the reinforcement width affected the pullout force for the geosynthetic strips at the same tensile strength. The pullout behavior was evidenced within a range of approximately 0.45 L of the total length of the reinforcement (L) and hardly occurred beyond a certain distance from the geosynthetic strips front regardless of the normal stress. Based on these pullout behavioral characteristics, a method is proposed for the prediction of the effective length (LE) and maximum effective length (LE(max)) of a geosynthetic strip. The pullout strength was compared using the total area and effective area methods in accordance with the proposed method. In the case of the total area method, GS50W (width: 50 mm) and GS70W (width: 70 mm) exhibited similar pullout strengths. The pullout strength by the effective area method, however, was found to be affected by the soil-reinforcement interface adhesion. The proposed method used for the prediction of the effective length of a geosynthetic strip was evaluated using a design case. It was confirmed that the method achieved an economical design in instances in which the pullout resistance by the effective length (LE) was applied compared with the existing method.

Strength Characteristics of Controlled Low-Strength Materials with Waste Paper Sludge Ash (WPSA) for Prevention of Sewage Pipe Damage.

In this study, the effects of the mixing conditions of waste paper sludge ash (WPSA) on the strength and bearing capacity of controlled low-strength material (CLSM) were evaluated, and the optimal mixing conditions were used to evaluate the strength characteristics of CLSM with recyclable WPSA. The strength and bearing capacity of CLSM with WPSA were evaluated using unconfined compressive strength tests and plate bearing tests, respectively. The unconfined compressive strength test results show that the optimal mixing conditions for securing 0.8-1.2 MPa of target strength under 5% of cement content conditions can be obtained when both WPSA and fly ash are used. This is because WPSA and fly ash, which act as binders, have a significant impact on overall strength when the cement content is low. The bearing capacity of weathered soil increased from 550 to 575 kPa over time, and CLSM with WPSA increased significantly, from 560 to 730 kPa. This means that the bearing capacity of CLSM with WPSA was 2.0% higher than that of weathered soil immediately after construction; furthermore, it was 27% higher at 60 days of age. In addition, the allowable bearing capacity of CLSM corresponding to the optimal mixing conditions was evaluated, and it was found that this value increased by 30.4% until 60 days of age. This increase rate was 6.7 times larger than that of weathered soil (4.5%). Therefore, based on the allowable bearing capacity calculation results, CLSM with WPSA was applied as a sewage pipe backfill material. It was found that CLSM with WPSA performed better as backfill and was more stable than soil immediately after construction. The results of this study confirm that CLSM with WPSA can be utilized as sewage pipe backfill material.

Tim-4 functions as a scavenger receptor for phagocytosis of exogenous particles.

The phosphatidylserine (PS) receptor Tim-4 mediates phagocytosis of apoptotic cells by binding to PS exposed on the surface of these cells, and thus functions as a PS receptor for apoptotic cells. Some of PS receptors are capable of recognizing other molecules, such as LPS on bacteria, besides PS on apoptotic cells. However, it is unclear whether Tim-4 perceives other molecules like the PS receptors. Here, we report that Tim-4 facilitates the phagocytosis of exogenous particles as well as apoptotic cells. Similar to the process that occurs during Tim-4-mediated efferocytosis, the uptake of exogenous E. coli and S. aureus bioparticles was promoted by overexpression of Tim-4 on phagocytes, whereas phagocytosis of the bioparticles was reduced in Tim-4-deficient cells. A truncation mutant of Tim-4 lacking the cytoplasmic tail promoted phagocytosis of the particles, but a mutant lacking the IgV or the mucin domain failed to enhance phagocytosis. However, expression of Tim-4AAA (a mutant form of Tim-4 that does not bind phosphatidylserine and does not promote efferocytosis) still promoted phagocytosis. Tim-4-mediated phagocytosis was not blocked by expression of the phosphatidylserine-binding protein Anxa5. Furthermore, binding of lipopolysaccharide (LPS), which is found in the outer membrane of Gram-negative bacteria, was higher in Tim-4-overexpressing cells than in Tim-4-deficient cells. In summary, our study suggests that Tim-4 acts as a scavenger receptor and mediates phagocytosis of exogenous particles in a phosphatidylserine-independent manner.

Effect of Prior Direction Expectation on the Accuracy and Precision of Smooth Pursuit Eye Movements.

The integration of sensory with top-down cognitive signals for generating appropriate sensory-motor behaviors is an important issue in understanding the brain's information processes. Recent studies have demonstrated that the interplay between sensory and high-level signals in oculomotor behavior could be explained by Bayesian inference. Specifically, prior knowledge for motion speed introduces a bias in the speed of smooth pursuit eye movements. The other important prediction of Bayesian inference is variability reduction by prior expectation; however, there is insufficient evidence in oculomotor behaviors to support this prediction. In the present study, we trained monkeys to switch the prior expectation about motion direction and independently controlled the strength of the motion stimulus. Under identical sensory stimulus conditions, we tested if prior knowledge about the motion direction reduced the variability of open-loop smooth pursuit eye movements. We observed a significant reduction when the prior expectation was strong; this was consistent with the prediction of Bayesian inference. Taking advantage of the open-loop smooth pursuit, we investigated the temporal dynamics of the effect of the prior to the pursuit direction bias and variability. This analysis demonstrated that the strength of the sensory evidence depended not only on the strength of the sensory stimulus but also on the time required for the pursuit system to form a neural sensory representation. Finally, we demonstrated that the variability and directional bias change by prior knowledge were quantitatively explained by the Bayesian observer model.

A scaffold for signaling of Tim-4-mediated efferocytosis is formed by fibronectin.

An essential step during clearance of apoptotic cells is the recognition of phosphatidylserine (PS) exposed on apoptotic cells by its receptors on phagocytes. Tim-4 directly binding to PS and functioning as a tethering receptor for phagocytosis of apoptotic cells has been extensively studied over the past decade. However, the molecular mechanisms by which Tim-4 collaborates with other engulfment receptors during efferocytosis remain elusive. By comparing efferocytosis induced by Tim-4 with that by Anxa5-GPI, an artificial tethering receptor, we found that Tim-4 possesses auxiliary machinery to induce a higher level of efferocytosis than Anxa5-GPI. To search for that, we performed a yeast two-hybrid screen and identified Fibronectin (Fn1) as a novel Tim-4-associating protein. Tim-4 directly associated with Fn1 and formed a complex with integrins via the association of Fn1. Through Tim-4-/- mice and cell-based assays, we found that modulation of the Fn1 level affected efferocytosis induced by Tim-4 and disruption of the interaction between Tim-4 and Fn1 abrogated Tim-4-mediated efferocytosis. In addition, Tim-4 depletion attenuated integrin signaling activation and perturbation of integrin signaling suppressed Tim-4-promoted efferocytosis. Taken together, the data suggest that Fn1 locates Tim-4 and integrins in close proximity by acting as a scaffold, resulting in synergistic cooperation of Tim-4 with integrins for efficient efferocytosis.

Management of Coronary Sinus Ostial Atresia during a Staged Operation of a Functional Single Ventricle.

Coronary sinus ostial atresia (CSOA) with persistent left superior vena cava (LSVC) in the absence of an unroofed coronary sinus is a benign and rare anomaly that may be taken lightly in most instances. However, if overlooked in patients undergoing univentricular heart repair such as bidirectional Glenn or Fontan-type surgery, fatal surgical outcomes may occur due to coronary venous drainage failure. We report a case of CSOA with a persistent LSVC that was managed through coronary sinus rerouting during a total cavopulmonary connection, and provide a review of the literature regarding this rare anomaly.

Prenatal diagnosis of isolated coronary arteriovenous fistula.

Coronary arteriovenous fistula (CAVF) is a rare condition defined as an anomalous termination of the coronary arteries. The etiology of CAVF is either congenital or acquired, and iatrogenic CAVF is most commonly caused by cardiovascular surgery or percutaneous intervention. Most of the prenatally diagnosed CAVFs were related to complex heart disease, and only few cases of an isolated CAVF have been reported to date. We successfully diagnosed an isolated CAVF by fetal echocardiography at 25.3 weeks of gestation. Accurate prenatal diagnosis resulted in the prompt decision for postnatal surgical correction, and the neonate thrived well without any complications.

Fontan Revision with Y-Graft in a Patient with Unilateral Pulmonary Arteriovenous Malformation.

The extracardiac conduit Fontan procedure is the last surgical step in the treatment of patients with a functional single ventricle. An acquired pulmonary arteriovenous malformation may appear perioperatively or postoperatively due to an uneven hepatic flow distribution. Here we report a case of a bifurcated Y-graft Fontan operation in a 15-year-old male patient with a unilateral pulmonary arteriovenous malformation after an extracardiac conduit Fontan operation.

Evaluation of commissural malalignment of aortic-pulmonary sinus using cardiac CT for arterial switch operation: comparison with transthoracic echocardiography.

BACKGROUND: There are limited data regarding the influence of commissural malalignment of the aortic-pulmonary sinus on the arterial switch operation. OBJECTIVE: To compare diagnostic accuracy between cardiac CT and echocardiography for evaluating commissural malalignment of aortic-pulmonary sinus in children with complete transposition of the great arteries and to seek potential clinical implication of commissural malalignment on the arterial switch operation. MATERIALS AND METHODS: In 37 patients (35 boys; median age: 8 days, range: 3-80 days) with complete transposition of the great arteries who had tricuspid semilunar valves and underwent an arterial switch operation, the degree of the commissural rotation of the aortic-pulmonary sinus was assessed on cardiac CT (n=37) and echocardiography (n=35). With surgical finding as a reference, cardiac CT was compared with echocardiography in identifying commissural malalignment in 35 patients. The influence of the height difference between the semilunar valves measured by cardiac CT on the identification of commissural malalignment with cardiac CT and echocardiography was evaluated. The impact of commissural malalignment on coronary transfer techniques was evaluated. RESULTS: In operative findings, the commissures of the semilunar valves were aligned in 24 patients and malaligned in 13. With surgical findings as a reference, cardiac CT showed higher, but not statistically significant (P>0.05), sensitivity (91.7% vs. 75.0%), specificity (87.0% vs. 78.3%) and accuracy (88.6% vs. 77.1%) for the diagnosis of the malalignment than echocardiography. The measured height difference between the semilunar valves did not affect the identification of the malalignment with cardiac CT and echocardiography. The surgical malalignment group showed a higher requirement of modified coronary transfer techniques than the surgical aligned group (11/13 vs. 11/24, P=0.03). CONCLUSION: Cardiac CT and echocardiography appear useful for evaluating commissural malalignment of the semilunar valves in patients with complete transposition of the great arteries frequently requiring modified coronary transfer techniques at during an arterial switch operation.

Cardiac allograft vasculopathy after heart transplantation: Is it really ominous?

OBJECTIVES: Cardiac allograft vasculopathy (CAV) remains a major impediment to long-term survival after heart transplantation (HT). We investigated the incidence, disease course, and risk factors for CAV. METHODS: Among 399 patients who underwent HT between November 1992 and July 2014, 297 survivors were reviewed. Endpoints were CAV development and the composite outcome of death or re-HT. RESULTS: During 5.6±5.2 years, CAV was detected in 54 patients: 45 (83.3%), 8 (14.8%), and 1 (1.8%) patients for CAV 1, 2, and 3, respectively. At 1, 5, and 10 years, 99.0%, 82.4%, and 60.3% of patients were free of CAV, respectively. Only four patients (7.4%) showed progression over 4.8±2.1 years' follow-up. The presence of CAV did not affect the composite outcome (P=.89). Predictors of CAV included donor age (HR1.06, 95% CI: 1.03-1.10: P<.001), recipient age (1.03 [1.003-1.06]; P=.03), ischemic time >240 minutes (3.15 [1.36-7.28], P=.007), postoperative renal replacement therapy (RRT) (7.1 [2.3-21.8]; P=.001), and triglyceride level at 1 year post-HT (1.005 [1.002-1.008], P=.003). CONCLUSIONS: CAV incidence after HT appears acceptable, with most cases being stationary and inconsequential for survival. Development of CAV seems to be influenced by donor and recipient age, ischemic time, postoperative RRT, and high triglyceride level.

Systemic-Pulmonary Shunt Facilitates the Growth of the Pulmonary Valve Annulus in Patients With Tetralogy of Fallot.

BACKGROUND: Transannular patching (TAP) frequently accompanies primary repairs (PRs) in symptomatic neonates with tetralogy of Fallot (TOF). If a systemic-pulmonary shunt (SPS) facilitates the growth of the pulmonary valve annulus (PVA), patients with a marginally small PVA could benefit from a staged repair in terms of lowering the risk of TAP. METHODS: Among 216 infants with TOF who underwent surgical intervention between January 2004 and December 2013, 29 infants underwent SPS with a subsequent repair (SPS group), whereas 187 infants received a PR (PR group). Median age and the Z-score of the PVA (PVA [Z]) at SPS were 32 days and -3.5, respectively. There was one late death and one follow-up loss after SPS, and preservation of the PVA was achieved on repair in 16 patients (16 of 29; 55%). RESULTS: Multiple regression analysis showed that performance of SPS was the only indicator of the increase in the PVA (Z) in the entire cohort (n = 216). On mixed linear regression, the PVA (Z) increased significantly after the placement of an SPS (-3.6 + 0.2*duration in months, p = 0.001), whereas the prerepair changes in the PVA (Z) were not statistically significant in the PR group (p = 0.7), with a significant intergroup difference (p < 0.001). Receiver operating characteristic curve analysis showed that placement of TAP is expected when the preshunt PVA (Z) is smaller than -4.2 (area under the curve: 0.82; 95% confidence interval: 0.62 to 1.00; sensitivity, 100%; specificity, 73%). CONCLUSIONS: SPS facilitates outgrowth of the PVA over somatic growth in patients with TOF. However, preservation of the PVA may not be achieved on staged repair if the initial PVA is too small.

Aortic Root Translocation with Arterial Switch for Transposition of the Great Arteries or Double Outlet Right Ventricle with Ventricular Septal Defect and Pulmonary Stenosis.

Double outlet right ventricle (DORV) and transposition of the great arteries (TGA) with ventricular septal defect (VSD) and pulmonary stenosis (PS) are complex heart diseases, the treatment of which remains a surgical challenge. The Rastelli procedure is still the most commonly performed treatment. Aortic root translocation including an arterial switch operation is advantageous anatomically since it has a lower possibility of conduit blockage and the left ventricle outflow tract remains straight. This study reports successful aortic root transpositions in two patients, one with DORV with VSD and PS and one with TGA with VSD and PS. Both patients were discharged without postoperative complications.

The First Successful Heart-Lung Transplant in a Korean Child with Humidifier Disinfectant-Associated Interstitial Lung Disease.

From 2006 to 2011, an outbreak of a particular type of childhood interstitial lung disease occurred in Korea. The condition was intractable and progressed to severe respiratory failure, with a high mortality rate. Moreover, in several familial cases, the disease affected young women and children simultaneously. Epidemiologic, animal, and post-interventional studies identified the cause as inhalation of humidifier disinfectants. Here, we report a 4-year-old girl who suffered from severe progressive respiratory failure. She could survive by 100 days of extracorporeal membrane oxygenation support and finally, underwent heart-lung transplantation. This is the first successful pediatric heart-lung transplantation carried out in Korea.

Detachment of the tricuspid valve for ventricular septal defect closure in infants younger than 3 months.

OBJECTIVES: Although several previous studies have reported that a ventricular septal defect (VSD) can be closed safely through the detached tricuspid valve (TV) without impairing TV function, this has not been demonstrated for infants younger than 3 months. METHODS: We enrolled 296 infants younger than 3 months who underwent VSD closure through the right atrium between January 2004 and December 2013. In the study group of 49 patients (16.6%), the TV was detached for better exposure of the defect. RESULTS: The median age and weight were 63.5 days (14-90 days) and 4.4 kg (2.1-6.7 kg), without intergroup differences. Abnormal chordal attachment of the TV in preoperative echocardiography was associated with detachment of the TV during surgery (P = .001). Cardiopulmonary bypass (P = .001) and aortic crossclamp (P < .001) times were significantly longer in the study group. A permanent pacemaker was required for 2 patients in the control group. Follow-up echocardiography was available for 282 patients at a median of 21 months (1-108 months) after the operation. On final echocardiography, tricuspid regurgitation greater than grade 2 was observed in 1 patient in the study group and residual VSD existed in 4 patients (1 in the study group), without statistical significance. CONCLUSIONS: Detachment of the TV can be used safely for better exposure of the VSD without increased risk of tricuspid regurgitation in infants younger than 3 months. Preoperative echocardiography might be useful for predicting the possibility of detachment of the TV for enhancing exposure of the VSD.