Computational fluid dynamics in the evaluation of hemodynamic performance of cavopulmonary connections after the Norwood procedure for hypoplastic left heart syndrome

OBJECTIVE: Computational fluid dynamics have been used to study the hemodynamic performance of surgical operations, resulting in improved design. Efficient designs with minimal energy losses are especially important for cavopulmonary connections. The purpose of this study was to compare hydraulic performance between the hemi-Fontan and bidirectional Glenn procedures, as well as the various types of completion Fontan operations. METHODS: Three-dimensional models were constructed of typical hemi-Fontan and bidirectional Glenn operations according to anatomic data derived from magnetic resonance scans, angiocardiograms, and echocardiograms. Boundary conditions were imposed, and fluid dynamics were calculated from a mathematic code. Power losses, flow distribution to each lung, and pressures were measured at three predetermined levels of pulmonary arteriolar resistance. Models of the lateral tunnel, total cavopulmonary connection, and extracardiac conduit completion Fontan operations were constructed, and power losses, total flow distribution, vena caval and pulmonary arterial pressures, and flow distribution of inferior vena caval return were calculated. RESULTS: The hemi-Fontan and bidirectional Glenn procedures performed nearly identically, with similar power losses and nearly equal flow distributions to each lung at all levels of pulmonary arteriolar resistance. However, the lateral tunnel Fontan procedure as performed after the hemi-Fontan operation had lower power losses (6.9 mW, pulmonary arteriolar resistance 3 units) than the total cavopulmonary connection (40.5 mW) or the extracardiac conduit (42.9 mW), although the inclusion of an enlargement patch toward the right in the total cavopulmonary connection was effective in reducing the difference (10.0 mW). Inferior vena caval flow to the right lung was 52% for the lateral tunnel, compared with 19%, 30%, 19%, and 15% for the total cavopulmonary connection, total cavopulmonary connection with right-sided enlargement patch, extracardiac conduit, and extracardiac conduit with a bevel to the left lung, respectively. CONCLUSIONS: According to these methods, the hemi-Fontan and bidirectional Glenn procedures performed equally well, but important differences in energy losses and flow distribution were found after the completion Fontan procedures. The superior hydraulic performance of the lateral tunnel Fontan operation after the hemi-Fontan procedure relative to any other method may be due to closer to optimal caval offset achieved in the surgical reconstruction.     

Computational fluid dynamic study of flow optimization in realistic models of the total cavopulmonary connections

OBJECTIVES AND BACKGROUND: In the Fontan circulation, pulmonary and systemic vascular resistances are in series. The influence of various inferior vena cava to pulmonary artery connections in this unique circulatory arrangement was evaluated using computation fluid dynamics methods. METHODS: Realistic three-dimensional models of total cavopulmonary connections were created from angiographic measurements to include the hepatic vein, superior vena cava, and branches of the pulmonary arteries. Steady-state finite volume analyses were performed using identical in vivo boundary conditions. Computational solutions calculated the percent hydraulic power dissipation and left-to-right pulmonary arterial flow distribution. RESULTS: Simulations of the lateral tunnel, intra-atrial tube, extracardiac conduit with left and right pulmonary artery anastomosis demonstrated extracardiac conduit with left pulmonary artery anastomosis having the lowest energy loss. Varying the extracardiac conduit from 10 to 30 mm resulted in the least energy dissipation at 20 mm. Serial dilation of the lateral tunnel pathway showed a small incremental worsening of energy loss. CONCLUSIONS: Maximizing energy conservation in a low-energy flow domain, such as the Fontan circulation, can be significant to its fluid dynamic performance. Although computational modeling cannot predict postoperative failure or functional outcome, this study confirms the importance of local geometry of the surgically created pathway in the total cavopulmonary connection.     

Total Extracardiac Right Heart Bypass Using a Polytetrafluoroethylene Graft

A bstract Background : With regard to hemodynamics and late arrhythmias, total cavopulmonary connection has been accepted as a superior technique as compared to Fontan type procedures. However, intra-atrial baffles for lateral tunnel or conduit remain construction retain some similar disadvantages. Patients and Methods : As an alternative to total cavopulmonary connection, total extracardiac right heart bypass using a polytetrafluoroethylene tube for the inferior vena cava to pulmonary artery connection may obviate some problems. Five patients with complex heart disease necessitating one ventricle repair underwent this procedure successfully. Results : Aortic cross-clamp time ranged from 0 to 24 minutes (mean = 15.8 min). No case required takedown or an additional step. Although the follow-up periods have been relatively short (mean = 19 months), all patients are well and no arrhythmic event or thromboembolic episode has occurred. Conclusions : As a simple, safe, and reproducible procedure, total extracardiac right heart bypass is an alternative to Fontan or total cavopulmonary connection procedure.     

The beneficial vortex and best spatial arrangement in total extracardiac cavopulmonary connection

OBJECTIVE: Total extracardiac cavopulmonary connection is an established procedure, but the best spatial arrangement remains controversial. On the basis of our clinical experience with total extracardiac cavopulmonary connection, we performed quantitative and qualitative flow analysis on total extracardiac cavopulmonary connection models simulating the two most frequent arrangements applied to our patients to determine the most favorable hydrodynamic pattern. METHODS: We selected two main groups among 110 patients who underwent total extracardiac cavopulmonary connection, those with left-sided inferior vena cava anastomosis (type 1) and those with facing superior and inferior vena cava anastomoses (type 2). Blown-glass total extracardiac cavopulmonary connection phantom models were constructed on the basis of nuclear magnetic resonance and angiographic images. Flow measurements were performed with a Nd:YAG Q-switched laser and a particle imaging velocimetry system. A power dissipation study and a finite-element numeric simulation were also carried out. RESULTS: When applying superior and inferior vena caval flow proportions of total systemic venous return of 40% and 60%, respectively, a vortex was visualized in the type 1 phantom that rotated counterclockwise at the junction of the caval streams. This apparent vortex was not a true vortex; rather, it represented a weakly dissipative recirculating zone modulating the flow distribution into the pulmonary arteries. The power dissipation and finite-element numeric stimulation confirmed the beneficial nature of the apparent vortex and a more energy-saving pattern in the type 1 phantom than in the type 2 phantom. CONCLUSION: Total extracardiac cavopulmonary connection with left-sided diversion of the inferior vena caval conduit anastomosis is characterized by a central vortex that regulates the caval flow partitioning and provides a more favorable energy-saving pattern than is seen with the total extracardiac cavopulmonary connection with directly opposed cavopulmonary anastomoses.     

全腔静脉-肺动脉连接术的回顾与展望

Fontan手术迄今仍是治疗单心室一类复杂先天性心脏病的主要手段。Fontan手术方法从1968年问世以来有许多改进,早期应用的心房-肺动脉连接术已为全腔静脉-肺动脉连接术所取代。通过对心房内隧道和心外管道全腔静脉-肺动脉连接术的中、晚期手术疗效进行比较分析,心外管道优点更多。然而,由于缺乏右心室的泵血功能,晚期循环衰竭最终都难以避免。当Fontan循环衰竭药物治疗无效时,惟一的选择是心脏移植,但后者供体来源缺乏。目前正研究开发的,旨在＂双心室化＂单心室Fontan循环的腔-肺机械辅助装置,有很好的前景。近年来胎儿心脏病诊疗技术的进展也拓宽了治疗复杂先天性心脏病的径路,经导管扩张严重主动脉瓣狭窄防止发展为左心室发育不全综合征,以增加双心室修复的机会;或对不能根治的复杂先天性心脏病患者终止妊娠,以降低此类复杂先天性心脏病的出生率等。我们结合文献对Fontan手术的方法进行回顾和展望。     

Midterm surgical results of total cavopulmonary connection: clinical advantages of the extracardiac conduit method

OBJECTIVE: We evaluated the midterm surgical outcomes of intra-atrial lateral tunnel and extracardiac conduit total cavopulmonary connection to clarify the clinical superiority. METHODS: Patients (n = 167) underwent total cavopulmonary connection (88 with lateral tunnel and 79 with extracardiac conduit) from November 1991 to March 1999. Survival, incidence of reoperation and late complications, exercise tolerance, hemodynamic variables, and plasma concentration of natriuretic peptide type A were compared. In the lateral tunnel group, time-related change in lateral tunnel size was investigated for its relationship to postoperative arrhythmias. RESULTS: The 8-year survival was 93.2% in the lateral tunnel group and 94.9% in the extracardiac conduit group. Seven reoperations were performed in the lateral tunnel group but none in the extracardiac conduit group. Supraventricular arrhythmias developed in 14 patients (15.9%) in the lateral tunnel group and in 4 patients (5.1%) in the extracardiac conduit group (P =.003). Freedom from cardiac-related events was 72.5% in the lateral tunnel group and 89.8% in the extracardiac conduit group at 8 years (P =.0098). Hemodynamic variables and exercise tolerance were similar in both groups but plasma natriuretic peptide type A concentration, a parameter of atrial wall tension, was higher in the lateral tunnel group. In the lateral tunnel group, intra-atrial tunnel size increased by 19.4% during the 44.2-month interval and the percent increase in tunnel size was an independent predictor of supraventricular arrhythmias. CONCLUSIONS: The midterm survival, hemodynamic variables, and exercise tolerance were similar and satisfactory in both lateral tunnel and extracardiac conduit groups; however, the incidence of cardiac-related events was significantly less frequent in the extracardiac conduit group. In the lateral tunnel group, careful observation is required to monitor the relationship of the dilating tendency of the intra-atrial tunnel and the development of late complications.     

Total cavopulmonary connection with an extracardiac conduit: experience with 100 patients

BACKGROUND: In the Fontan procedures total cavopulmonary connection with an extracardiac conduit is a concern. The potential benefits of an extracardiac conduit may be the avoidance of postoperative supraventricular arrhythmias over the long-term, hemodynamic benefits due to laminar flow, possibility of completion without anoxic arrest, and applicability to anomalous systemic or pulmonary venous return, or both anomalous systemic and pulmonary venous return. We demonstrate early to midterm results of total cavopulmonary connection with an extracardiac conduit. METHODS: Between March 1994 and February 2000, a total of 100 patients underwent total cavopulmonary connection with an extracardiac conduit. In 27 patients, who underwent a single stage total cavopulmonary connection operation, 7 were done without palliation. Seventy-three patients had undergone a bidirectional Glenn shunt before completion of the total cavopulmonary connection. We used an expanded polytetrafluoroethylene tube graft as the extracardiac conduit. RESULTS: Cardiopulmonary bypass time was 133.2+/-55.2 minutes. Myocardial ischemic time was 38.5+/-23.2 minutes in 40 patients who needed cardioplegic cardiac arrest for intracardiac procedures. Intraoperative fenestration was done in only 1 patient. There were no operative deaths. During follow-up of 37.3 months, there were 5 late deaths. When compared with the patients treated by the lateral tunnel technique in our institute, there was no significant difference in actuarial survival rate, but the event free rate of the extracardiac conduit group was significantly superior to the lateral tunnel group. CONCLUSIONS: Total cavopulmonary connection with the extracardiac conduit produced good results in short to midterm follow-up.     

心外管道全腔静脉肺动脉连接术

目的 报告心管道全腔静脉肺动脉连接术（TECPC）应用经验。方法 横断上腔静脉与右肺动脉端侧吻合,切断下腔静脉前壁,保留原位吻合口,将下腔静脉通过人工血管与主肺动脉吻合,共治疗9例复杂性先天性心脏病,其中1例单心室改良Fontan术后4年频发室上性心动过速而改行TECPC。结果 全组手术后均生存。3例术后出现胸腔积液、乳糜胸并发症、均治愈。血流动力学指标满意,术后随访心功能Ⅰ-Ⅱ级,无心律紊乱发生。结论 TECPC手术操作简单,并发症少,适应证广泛,优于改良Fontan手术和传统的全腔静脉肺动脉连接术。     

改良全腔静脉-肺动脉连接术治疗功能性单心室

目的 为了进一步改善全腔静脉－肺动脉连接手术的效果,探讨其经典手术方式的改良方法。方法 对１３例功能性单心室施行了改良全腔静脉－肺动脉妆手术 上腔静脉远心民右肺动脉上缘作端侧吻合,吻合口尽量偏左,近心端与右肺动脉下缘吻合,吻合口尽量偏右。其中５便在心脏不停跳下用Ｇｏｒｅ－Ｔｅｘ心外管道连接下腔静脉与右肺动脉下缘,８例采用心房内隧道。结果 术后早期死亡１例（７．７％）,１２例（９２．３％）存活者术后     

Presurgical Evaluation of Fontan Connection Options for Patients With Apicocaval Juxtaposition Using Computational Fluid Dynamics

Apicocaval juxtaposition (ACJ) is a rare congenital heart defect associated with single ventricle physiology where optimal positioning of the Fontan conduit for completion of total cavopulmonary connection (TCPC) is still controversial. In ACJ, the cardiac apex is ipsilateral with the inferior vena cava (IVC), risking kinking and collapse of the Fontan conduit at the apex of the heart. The purpose of this study is to evaluate two viable routes for Fontan conduit connection in patients with ACJ, using computational fluid dynamics. Internal energy loss evaluations were used to determine contribution of conduit curvature to the energy efficiency of each cavopulmonary anastomosis configuration. This percentage of energy loss contribution was found to be greater in the case of a curved extracardiac conduit connection (44%, 4.1 mW) traveling behind the ventricular apex, connecting the IVC to the left pulmonary artery, than the straighter lateral tunnel conduit (6%, 1.4 mW) installed through the ventricular apex. In contrast, net energy loss across the anastomosis was significantly lower with extracardiac TCPC (9.3 mW) in comparison with lateral tunnel TCPC (23.2 mW), highlighting that a curved Fontan conduit is favorable provided that it is traded off for a superior cavopulmonary connection efficiency. Therefore, a relatively longer and curved Fontan conduit has been demonstrated to be a suitable connection option independent of anatomical situations.     

Extracardiac total cavopulmonary connection using a Y-shaped graft

We report on 17-year-old Fontan candidate with a seerely distorted central pulmonary artery (PA) who underwent a successful extracardiac total cavopulmonary connection using a Y-shaped bifurcated graft. A nonanatomic pathway from the inferior vena cava to the left PA was constructed and positioned anterior to the ascending aorta. The other arm was used as a conduit between the inferior vena cava and the right PA. All procedures were performed under temporary venous bypass without cardiopulmonary bypass.     

Extracardiac total cavopulmonary connection using a tissue-engineered graft

OBJECTIVE: Extracardiac and lateral tunnel total cavopulmonary connection are currently 2 major options for patients with a single ventricle physiology. However, each procedure has some disadvantages over the other. We developed a new technique of extracardiac total cavopulmonary connection using a tissue-engineered graft to overcome some of the disadvantages previously associated with both the extracardiac and lateral tunnel procedures. METHODS: Between February 2001 and October 2002, 8 patients underwent an extracardiac total cavopulmonary connection using a tissue-engineered graft in our institution. Collected bone marrow cells (1 x 10(8) mononucleocytes) from a patient (approximately 1-4 mL/kg body weight) were seeded onto a biodegradable scaffold composed of polycaprolactone-polylactic acid copolymer reinforced with woven polylactic acid. After a 2- to 4-hour cultivation, the seeded scaffold was implanted as an extracardiac conduit during the total cavopulmonary connection operation. RESULTS: There were no hospital or late deaths. At a mean follow-up of 13.4 months (range 4-25 months), all patients are alive and asymptomatic with no need for repeat surgery. A postoperative catheter examination or computed tomography showed all tissue-engineered grafts to be patent and revealed no stenosis, obstruction, or aneurysmal change in the 8 patients. CONCLUSION: We believe that extracardiac total cavopulmonary connection using a tissue-engineered graft has the potential to overcome some of the disadvantages previously associated with extracardiac or lateral tunnel total cavopulmonary connection. However, an extended follow-up period is required to clarify the long-term clinical outcome for the tissue-engineered graft.     

小儿复杂先天性心脏病侧通道和外管道Fontan术比较

目的 总结侧通道和外管道Fontan术纠治小儿危重复杂型先天性心脏病(先心病)的经验.方法 2000年1月至2006年12月128例复杂型心内畸形病儿行改良Fontan术治疗.男76例,女52例.年龄1.9～16.5岁,平均(6.2±3.8)岁;体重8～62 kg,平均(19.0±5.5)kg.病种主要有单心室(SV)59例;右室双出口(DORY)Z5例等.一期Fontan术87例;二期Fontan术41例.两次手术间隔0.8～7.3年,平均(3.9±2.8)年.首次手术为单侧Glenn术(12例)、双侧双向Glenn术(8例)等.行心内侧通道(LT)的Fontan组(LT组)89例,行外管道(ECC)的Fontan组(ECC组)39例.术前均行二维多普勒超声,11例加做核磁共振,30例行心导管和心血管造影.结果 死亡17例(13.3%).LT组病儿年龄明显低于ECC组.32例发生低心输出量综合征,其中11例.肾功能受损导致无尿而行腹膜透析术(2～5 d后尿量恢复).LT组术后心律紊乱的发生率明显高于ECC组.门诊随访3～24个月,均未出现严重并发症,无死亡病例.结论 LT组术后心律紊乱的发生率明显高于ECC组,ECC的Fontan术具有可避免主动脉阻断和心肌缺血、缩短CPB时间和保持更为流线型的下腔静脉回流血的优点,开窗术的远期优越性未能明确.     

Revision of previous Fontan connections to total extracardiac cavopulmonary anastomosis: A multicenter experience

BACKGROUND: Conversion to total extracardiac cavopulmonary anastomosis is an option for managing patients with dysfunction of a prior Fontan connection. METHODS: Thirty-one patients (19.9 +/- 8.8 years) underwent revision of a previous Fontan connection to total extracardiac cavopulmonary anastomosis at four institutions. Complications of the previous Fontan connection included atrial tachyarrhythmias (n = 20), progressive heart failure (n = 17), Fontan pathway obstruction (n = 10), effusions (n = 10), pulmonary venous obstruction by an enlarged right atrium (n = 6), protein-losing enteropathy (n = 3), right atrial thrombus (n = 2), subaortic stenosis (n = 1), atrioventricular valve regurgitation (n = 3), and Fontan baffle leak (n = 5). Conversion to an extracardiac cavopulmonary connection was performed with a nonvalved conduit from the inferior vena cava to the right pulmonary artery, with additional procedures as necessary. RESULTS: There have been 3 deaths. Two patients died in the perioperative period of heart failure and massive effusions. The third patient died suddenly 8 months after the operation. All surviving patients were in New York Heart Association class I (n = 20) or II (n = 7), except for 1 patient who underwent heart transplantation. Early postoperative arrhythmias occurred in 10 patients: 4 required pacemakers, and medical therapy was sufficient in 6. In 15 patients, pre-revision arrhythmias were improved. Effusions resolved in all but 1 of the patients in whom they were present before revision. The condition of 2 patients with protein-losing enteropathy improved within 30 days. CONCLUSIONS: Conversion of a failing Fontan connection to extracardiac cavopulmonary connection can be achieved with low morbidity and mortality. Optimally, revision should be undertaken early in symptomatic patients before irreversible ventricular failure ensues.     

Inferior vena cava-pulmonary artery extracardiac conduit. A new form of right heart bypass

From November 1988 to May 1989, four patients underwent total right heart bypass by means of bidirectional cavopulmonary anastomosis and interposition of an extracardiac conduit from the inferior vena cava to the pulmonary artery. All of them had an uneventful postoperative course, and there have been no early or late deaths. We propose this technique as an alternative surgical option in candidates for a Fontan procedure with (1) hypoplasia or atresia of the left atrioventricular valve, (2) common atrioventricular valve, (3) anomalies of systemic and pulmonary venous return, or (4) auricular juxtaposition.     

In vivo flow dynamics of the total cavopulmonary connection from three-dimensional multislice magnetic resonance imaging

BACKGROUND: The total cavopulmonary connection (TCPC) design continues to be refined on the basis of flow analysis at the connection site. These refinements are of importance for myocardial energy conservation in the univentricular supported circulation. In vivo magnetic resonance phase contrast imaging provides semiquantitative flow visualization information. The purpose of this study was to understand the in vivo TCPC flow characteristics obtained by magnetic resonance phase contrast imaging and compare the results with our previous in vitro TCPC flow experiments in an effort to further refine TCPC surgical design. METHODS: Twelve patients with TCPC underwent sedated three-dimensional, multislice magnetic resonance phase contrast imaging. Seven patients had intraatrial lateral tunnel TCPC and 5 had extracardiac TCPC. RESULTS: In all patients in both groups a disordered flow pattern was observed in the inferior caval portion of the TCPC. Flow at the TCPC site appeared to be determined by connection geometry, being streamlined at the superior vena cava-pulmonary junction when the superior vena cava was offset and flared toward the left pulmonary artery. Without caval offset, intense swirling and dominance of superior vena caval flow was observed. In TCPC with bilateral superior vena cavae, the flow patterns observed included secondary vortices, a central stagnation point, and influx of the superior vena cava flow into the inferior caval conduit. A comparative analysis of in vivo flow and our previous in vitro flow data from glass model prototypes of TCPC demonstrated significant similarities in flow disturbances. Three-dimensional magnetic resonance phase contrast imaging in multiple coronal planes enabled a comprehensive semiquantitative flow analysis. The data are presented in traditional instantaneous images and in animated format for interactive display of the flow dynamics. CONCLUSIONS: Flow in the inferior caval portion of the TCPC is disordered, and the TCPC geometry determines flow characteristics.     

心外管道全腔静脉-肺动脉连接术的疗效

目的总结心外管道全腔静脉-肺动脉连接术(total cavopulmonary connection,TCPC)的经验,探讨手术适应证、手术设计、手术方法以及治疗效果.方法回顾分析29例心外管道TCPC患者的临床资料,平均年龄10岁,病种包括三尖瓣闭锁9例,左室型心室双入口9例,二尖瓣闭锁3例,右心室双出口合并左心室发育不良5例,矫正型大动脉转位解剖右心室发育不良3例.全部在体外循环下手术,12例采用心脏停搏,17例在并行转流心脏不停跳下手术.结果早期22例中死亡5例,后7例无死亡;随访3个月～10年,无晚期死亡.发生低心排血量综合征12例,乳糜胸11例.结论心外管道TCPC用于较大儿童或成人患者与其他Fontan类手术比较,临床长期效果较好.但应严格掌握手术适应证,合理的手术设计和术中细致操作,有危险因素时增用开窗术以及围术期严密观察和处理是提高手术近、远期治疗效果的关键.     

Total cavopulmonary connection using a pedicled pericardial conduit for a patient with apicocaval juxtaposition

A 5-year-old boy, with a double inlet solitary ventricle, pulmonary atresia, and apicocaval juxtaposition underwent an extracardiac total cavopulmonary connection. A pedicled pericardial conduit was placed behind the ventricle to make a straight pathway between the inferior vena cava and pulmonary artery. This report presents a solution for managing patients with complicated heart defects with apicocaval juxtaposition during the completion of a total cavopulmonary connection.     

心外管道全腔静脉-肺动脉连接术治疗复杂先天性心脏病

目的总结心外管道全腔静脉-肺动脉连接术（ECTCPC）治疗复杂先天性心脏病的临床经验,并就手术适应证、手术方法及手术效果进行讨论。方法1998年6月至2006年12月,68例先天性心脏复杂畸形的患者接受了ECTCPC。包括单心室伴有大动脉转位、肺动脉瓣狭窄45例：三尖瓣闭锁、右心室发育不良19例;三尖瓣下移畸形并右心室发育不良4例。其中合并永存左上腔静脉6例,双向Glenn术后行全腔静脉-肺动脉连接术18例（其中包括单心室、肺动脉闭锁、左肺动脉狭窄双向Glenn术后1例）,单心房、单心室、心上型完全性肺静脉异位引流、多发粗大体肺侧支1例。全组采用体外循环下手术共57例,其中8例患者因需要矫正心内畸形在主动脉阻断下手术外,其余49例均在全身麻醉并行体外循环心脏跳动下进行;非体外循环下手术11例。结果术后早期死亡2例,病死率为2．9％。其中1例死于术后反复肺内出血,1例死于上消化道反复大出血。66例痊愈出院,术后随访1个月至8年,无晚期死亡。所有患者症状消失,血氧饱和度90％～96％,恢复良好。结论ECTCPC方法简便易行,术后并发症较少,效果好,较其他术式有较大优点。     

Venous cannulation for extracorporeal circulation after total cavopulmonary connection with extracardiac conduit

We report two cases of venous cannulation after a total cavopulmonary connection (TCPC) with extracardiac conduit. Venous cannulation was performed via side graft sutured to the extracardiac conduit in an end-to-side fashion. The first case was a 3-year-old girl, who suffered from an atypical inferior vena cava obstruction after TCPC. The obstruction region was distal to the anastomosis site of extracardiac conduit and inferior vena cava. She underwent a surgical release of obstruction under cardiopulmonary bypass without circulatory arrest. The second case was a 2-year-old girl, who needed an extracorporeal membrane oxygenation support after TCPC due to severe low cardiac output syndrome. She was decannulated successfully after thirty-nine-hour support.