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.     

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.     

New approach to the surgical management of pulmonary arteriovenous malformations after cavopulmonary anastomosis

The development of pulmonary arteriovenous malformations after cavopulmonary bypass in patients with congenital heart disease is well documented. We report successful management of pulmonary arteriovenous malformations after cavopulmonary bypass in a patient with an interrupted inferior vena cava (IVC) and multiple hepatic veins utilizing an extracardiac conduit from the hepatic veins to the hemiazygous continuation of the interrupted IVC. This technique, performed without circulatory arrest or an atriotomy, may limit morbidity associated with intracardiac procedures in patients with single ventricle morphology. Furthermore, this case suggests an alternative technique for completion Fontan in patients with an interrupted IVC and multiple hepatic venous drainage.     

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.     

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.     

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.     

Management under anesthesia of a patient with renal cell carcinoma extending into the retrohepatic inferior vena cava with the aid of partial cardiopulmonary bypass]

A 70-year-old male with renal cell carcinoma extending into the retrohepatic inferior vena cava was scheduled for radical nephrectomy with vena caval resection under general anesthesia. He had received partial gastrectomy for gastric cancer twelve years before. Computed tomography and inferior vena cavography confirmed that the vena cava was almost completely occluded and that a collateral venous network was well established. It was considered that the surgical approach to the retrohepatic cavals area was technically very difficult, and that there was a high possibility of a pulmonary embolus during the surgical manipulation. To prevent a pulmonary embolus and get good control of the vena cava above the tumor and below the hepatic vein, we decided to use a partial cardiopulmonary bypass (CPB) until the vena cava was clamping above the tumor. Anesthesia was induced with propofol and fentanyl, and maintained with fentanyl and isoflurane-N2O-O2. In the partial CPB blood from the hepatic vein was drained from the inferior vena cava cannula through right atrium, oxygenated by microporus membrane oxygenator, and returned to the left femoral artery. Cannulation to drain the venous circulation entering the vena cava below the tumor was abandoned because the extensive collateral venous network ultimately drains into the superior vena cava. The partial CPB time was 90 min, and the bladder temperature during the CPB was 35-36 degrees C. During the 7.3 hr procedure, the pulmonary embolus did not occur and the total blood loss was 5515 ml. The patient made an uncomplicated recovery and was discharged 30 days after the operation. This newly reported partial-CPB method may be safe and effective for the management under anesthesia of other patients.     

Depopulated vena caval homograft: a new venous conduit

OBJECTIVE: Completion of the Fontan procedure is frequently performed by using an extracardiac conduit between the inferior vena cava and the pulmonary artery. Most centers use a polytetrafluoroethylene graft for the extracardiac conduit, and because re-endothelialization is unlikely, anticoagulation is used for a variable period. This study explores the use of an alternate large-caliber venous conduit. METHODS: The superior vena cava was replaced in 8 minipigs with either a polytetrafluoroethylene interposition graft (2 pigs) or a depopulated (acellular), cryopreserved superior vena caval homograft (6 pigs). After 6 months, the animals were killed, and the grafts were examined for patency and histology, including immunostaining. No anticoagulation was used. RESULTS: Polytetrafluoroethylene grafts have a cross-sectional luminal narrowing, ranging from 16% to 40%. Histology showed only partial intimal ingrowth, with excessive subendothelial fibrosis and early calcification. In contrast, the depopulated venous homografts showed minimal luminal narrowing, ranging from 2% to 9%. These grafts were completely repopulated by the recipient with an endothelial lining, which stained positively for factor VIII, and a subendothelial region appropriately recellularized by myofibroblasts, which stained positively for smooth muscle actin and procollagen. There was no evidence of an immune response to the venous homografts, as judged by staining for T-cell surface antigen, CD4, and CD8. Thrombus was not seen in any of the grafts. CONCLUSION: Depopulated, cryopreserved vena caval homografts might be superior conduits for cavopulmonary connection during completion of the Fontan operation by using the extracardiac conduit technique.     

Hemodynamic changes with initiation of veno-venous bypass in orthotopic liver transplant patients

Removal of the liver to start the anhepatic stage of liver transplantation requires cross-clamping of the portal vein, inferior vena cava, and hepatic artery. Adverse effects occur from engorged splanchnic beds and decreased venous return. A veno-venous bypass from the inferior vena cava and portal vein to the axillary vein is used in an attempt to ameliorate these changes. The purpose of this study was to evaluate the effect of institution of veno-venous bypass on hemodynamics. Eight randomly selected adult patients undergoing orthotopic liver transplantation had general anesthesia induced with thiamylal and maintained with nitrous oxide and isoflurane. Cardiopulmonary data and arterial and mixed venous blood gases were measured prospectively using radial artery and pulmonary artery catheters. Measurements were taken under four conditions: (1) 10 minutes before bypass; (2) after partial bypass (vena cava to the axillary vein); (3) after partial bypass with portal vein clamping; and (4) after full bypass (vena cava and portal vein to the axillary vein). Statistically significant changes seen were a 22% decrease in cardiac output and a 47% increase in systemic vascular resistance (SVR). Bypass flow was lower than predicted. Venovenous bypass ameliorates, but does not fully prevent, the reduction of cardiac output and rise in SVR seen with initiation of the anhepatic stage. However, bypass does prevent the hypotension experienced during cross-clamping and for these reasons should be used routinely.     

Model of complete separation of the hepatic veins from the systemic venous system

Background. In patients undergoing a Fontan operation, partial diversion of the hepatic veins to the pulmonary venous atrium has been tried with various techniques. They failed because of the development of intrahepatic collaterals leading to an unacceptable right-to-left shunting. We postulate that to avoid the formation of intrahepatic collaterals, the totality of the liver has to be drained into the same pressure compartment. We have designed a model of cavopulmonary anastomosis in which a prosthetic conduit reproduces an azygos continuation, associated with the diversion of the totality of the hepatic venous return. This article reports on the early hemodynamics and the fate of the separation of the two venous compartments in long-term survivors.

Methods. Eighteen goats were operated on; the pulmonary artery and hepatic vein pressures were recorded. During month 2, an opacification of the inferior vena cava and the cavopulmonary connection was performed. Between months 6 and 14, another opacification was performed, together with pressure recording at both ends of the conduit.

Results. Postoperatively the pulmonary artery pressure was pulsatile with a mean of 10 mm Hg and the hepatic vein pressure was 0 mm Hg. The first angiogram showed patent tubes with fast progression of the contrast. Throughout the inferior vena cava injection, there was no opacification of the portal or hepatic veins. The late study showed a narrowed conduit in all animals. During the injection, a collateral was injected, feeding into the inferior mesenteric vein. No collateral circulation could be seen draining directly into the liver. The median gradient between the two ends of the conduit was 11 mm Hg.

Conclusions. The isolation of the entire hepatic venous drainage is feasible and efficient for the separation of two pressure compartments. No intrahepatic collaterals are observed with this model at short- or long-term follow-up. The separation of the hepatic venous drainage should persist without collateral circulation as long as the inferior vena cava pressure stays at the levels observed in Fontan circulation.     

Distribution of hepatic venous blood in the total cavo-pulmonary connection: an in vitro study

Objectives: The objective of this project was to quantify the effects of geometry on the distribution of hepatic blood to the lungs in patients with a total cavo-pulmonary connection. The basis for this work is the supposition that hepatic blood is necessary for proper lung function. Methods: Plastic models of these connections were made with varying degrees of offset between the inferior and superior vena cava and attached to an in vitro flow loop. Dye was injected into the inferior vena cava and its concentration quantified in each pulmonary artery. These data were converted to percentage concentration and distribution of hepatic blood to each lung. Results: With no offset between the vena cava, hepatic blood distribution and concentration to each lung was similar to normal. For an offset of one or more diameters, hepatic blood tended to flow preferentially towards the nearest pulmonary artery with the opposite pulmonary artery exhibiting a deficit (<10% of normal). Conclusions: Distribution of hepatic blood to each lung was found to be a function of vena cava offset and pulmonary artery flow split. Under normal conditions, 60% of blood towards the right pulmonary artery, the hepatic blood distribution to both lungs could be maintained above 50% of normal if the inferior vena cava was offset towards the left pulmonary artery. Offsetting the inferior vena cava towards the right pulmonary artery jeopardized the delivery of hepatic blood to one lung.     

Hepatic vein-to-azygos vein connection in a patient with interrupted inferior vena cava.

Massive systemic-to-hepatic venous collaterals developed in a 8-year-old boy with left isomerism and azygos connection of the inferior vena cava who had undergone total cavopulmonary shunt leaving the hepatic vein connected to the common atrium 5 years previously. A hepatic vein-to-azygos vein connection via an autologous pericardial roll successfully ameliorated cyanosis and physical activity. Hepatic vein-to-azygos vein connection is technically easy and is favorable in providing balanced distribution of hepatic venous blood to both lungs. We recommend this technique as an effective alternative to hepatic vein-to-pulmonary artery connection in patients developing collateral vessels after total cavopulmonary shunt.     

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     

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.     

Thrombosis of intracardiac or extracardiac conduits after modified Fontan operation in patients with azygous continuation of the inferior vena cava.

BACKGROUND: The Fontan procedure in patients with azygous continuation of the inferior vena cava, requires a cavo-pulmonary anastomosis, and deviation of the hepatic venous drainage to the pulmonary arteries using an intra- or extracardiac conduit. METHODS: We report thrombosis of two pericardial conduits and one Gore-Tex (W. L. Gore & Assoc, Flagstaff, AZ) graft used for deviation of hepatic venous blood to the pulmonary arterial tree in 3 patients aged 11, 24, and 28 years. Two of the conduits (pericardial) were intraatrial. The Gore-Tex graft was placed in an extracardiac position. The two pericardial conduits obstructed completely. RESULTS: One patient died at reoperation. In the 2nd patient, the conduit was excised and the hepatic veins were allowed to drain into the atrium. In the 3rd patient, partial thrombosis of the Gore-Tex conduit was noted 30 months after operation. The thrombus resolved with oral anticoagulation. CONCLUSIONS: Conduits carrying only hepatic venous blood flow may have a higher risk of thrombosis. Anticoagulation or alternative methods of directing hepatic blood flow to the pulmonary circulation must be considered in these patients.     

Total cavopulmonary connection with innovative combined lateral tunnel and extracardiac conduit in heterotaxy syndrome

Total cavopulmonary connection remains a challenging procedure when treating heterotaxy syndrome patients with a widely separate drainage of the inferior vena cava and the hepatic vein into the common atrium. We trimmed a Gore-Tex tube graft (W.L. Gore & Associates, Flagstaff, AZ) to form a skirt to cover both openings of the inferior vena cava and the hepatic vein. This tubular structure pierces the atrium and travels outside the heart, and then reaches the inferior side of the pulmonary artery to avoid pulmonary vein obstruction. We then sutured the pierced atriotomy margin to the conduit. This innovative procedure has been shown to accommodate the widely separated hepatic vein drainage with a promising outcome.     

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.     

Urgency of operation in infracardiac total anomalous pulmonary venous connection

BACKGROUND: Because the tendency for pulmonary venous obstruction in the infracardiac type of total anomalous pulmonary venous connection may be partially dependent on the connection of the descending vein to the portal vein, the inferior vena cava, or one of their tributary vessels, we reviewed our surgical experience with various subtypes of infracardiac total anomalous pulmonary venous connection. METHODS: The urgency of operation in 4 neonates with infracardiac total anomalous pulmonary venous connection was reviewed. RESULTS: Two patients with pulmonary venous obstruction in whom the descending vein connected to the portal vein were operated on immediately with successful outcome. One patient who had become critically ill after the ductus venosus had closed died before operation could be undertaken. One patient in whom the descending vein connected to the left hepatic vein was operated on electively with successful outcome. CONCLUSIONS: In hemodynamically stable patients with no clinical or echocardiographic signs of pulmonary venous obstruction, some form of differentiation with regard to urgency of operation may be appropriate. When the descending vein connects to the inferior vena cava or a hepatic vein, the operation may be performed on a semi-elective basis. In contrast, when the descending vein connects to the portal vein or the ductus venosus, operation should generally not be delayed because of the high likelihood of obstruction.     

Interpostion vein graft in living donor liver transplantation

In adult-to-adult living donor liver transplantation (LDLT), right lobe grafts without a middle hepatic vein can cause hepatic congestion and disturbance of venous drainage. To solve this problem, various types of interposition vein graft have been used. OBJECTIVES: We used various types of interposition vein grafts for drainage of the paramedian portion of the right lobe in living donor liver transplantation. METHODS: From June 1996 to June 2003, 37 of 176 patients (128 adults, 48 pediatric) who underwent LDLT received vein grafts for drainage of segments V, VIII, or the inferior portion of the right lobe. RESULTS: In 36 adult cases the reconstruction included the inferior mesenteric vein of the donor (n = 14); cadaveric iliac vein stored at cold (4 degrees C) temperature (n = 5); cryopreserved (-180 degrees C) cadaveric iliac vein (n = 10); cryopreserved cadaveric iliac artery (n = 1 case); donor ovarian vein (n = 1); recipient umbilical vein (n = 3); recipient saphenous vein (n = 1); recipient left portal vein (n = 1); recipient left hepatic vein (n = 1). In a pediatric case with malignant hemangioendothelioma that encased and compressed the inferior vena cava, we used an interposition vein graft to replace the inferior vena cava. CONCLUSION: Various types of interposition vein grafts can be used in living donor liver transplantation. Cryopreserved cadaveric iliac vein and artery are useful to solve these drainage problems.     

Left superior vena cava draining into the left atrium, associated with partial anomalous pulmonary venous connection: surgical correction

A persistent left superior vena cava draining into the left atrium may produce a symptomatic right-to-left shunt. Although intra-atrial rerouting techniques, in patients with no connecting vein, have proved to be reliable and successful, in many cases the extracardiac repair is preferable. We report a case of a 5-month-old patient with a not connected left superior vena cava draining into the left atrium, associated with atrial septal defect and partial anomalous pulmonary venous connection. The correction has been achieved by rerouting the pulmonary venous return into the left atrium and by transposition of the left vena cava on the right appendage.