Bovine jugular vein thrombosis in the Fontan circulation

Tissue engineering: Relevance to neonatal congenital heart disease

Congenital heart disease (CHD) represents a large clinical burden, representing the most common cause of birth defect-related death in the newborn. The mainstay of treatment for CHD remains palliative surgery using prosthetic vascular grafts and valves. These devices have limited effectiveness in pediatric patients due to thrombosis, infection, limited endothelialization, and a lack of growth potential. Tissue engineering has shown promise in providing new solutions for pediatric CHD patients through the development of tissue engineered vascular grafts, heart patches, and heart valves. In this review, we examine the current surgical treatments for congenital heart disease and the research being conducted to create tissue engineered products for these patients. While much research remains to be done before tissue engineering becomes a mainstay of clinical treatment for CHD patients, developments have been progressing rapidly towards translation of tissue engineering devices to the clinic.

Superior Vena Cava Resection in Locally Advanced Thymoma-Surgical and Survival Outcomes

This study was aimed at reporting the surgical management of superior vena cava invasion in patients with locally advanced thymoma and to evaluate surgical and survival outcomes. This is a retrospective analysis of 12 patients operated for superior vena cava resection for locally advanced thymoma over 8 years in a thoracic surgery centre in India. An analysis of peri-operative variables including complications was carried out. The influence of various predictors on survival was assessed by log-rank test. Intra-operatively, superior vena cava (SVC) alone was involved in 3 (25%) cases, SVC with BCV involvement was there in 8 cases (66.7%) and in 1 patient, the SVC involvement extended into the right atrium also. In all cases, the tumour was resected en bloc with the involved part of SVC. Repair with primary closure was sufficient in 2 cases (16.6%) in view of < 1/3rd of circumferential involvement. However, in remaining 10 cases, SVC was replaced with PTFE graft (single graft in 6 cases, Y-graft in 2 cases and twin grafts in 2 cases). No peri-operative deaths. Overall survival (OS) at 1, 3 and 5 years was 100%, 91.6% and 83.3%, respectively. Myasthenia gravis and higher Masaoka stage (IV A) of the disease were poor predictors of survival. Superior vena cava resection and reconstruction is a feasible and oncologically superior option in invasive thymoma with SVC involvement. This challenging surgical procedure should only be attempted by an experienced team of thoracic and cardiac surgeons at high-volume centre to achieve best outcomes.

Prosthetic Reconstruction of Superior Vena Cava System for Thymic Tumor: A Retrospective Analysis of 22 Cases

OBJECTIVE

This study aimed to report our experience in superior vena cava (SVC) resection and reconstruction for 22 thymic tumor patients and to make comparisons with previous related reports.

METHODS

A retrospective study on 22 patients (15 thymomas, 7 thymic cancers) who underwent tumor resection with concomitant SVC reconstruction. All the patients underwent vascular conduit reconstruction by the cross-clamping technique. The corresponding data were reviewed, including clinical presentation, operation management (surgery procedure, selection of suitable graft, strategies against SVC syndrome, etc.), postoperative cares (antithrombotic agent application, treatments on brain edema, etc.), and follow-up information.

RESULT

Two patients were myasthenic, well controlled by oral pyridostigmine. All resections were radical (R0). Ten patients received induction treatment. All the 15 thymoma patients were Masaoka stage III (type B1-B3). As for thymic cancer, six patients were Masaoka stage III and one was stage IVa. Wedge pulmonary resection was performed in three patients (two right upper lobe, one both upper lobe). Procedures included were single graft replacement in 12 patients, bilateral grafts in 9, and Y-shaped graft in 1 patient. Anticoagulation and dehydration agents were routinely applied after operation. No perioperative mortalities were observed. Major complication rate was 9.1%. The median survival time was 44.2 months (range, 4-92 months). Three- and 5-year overall survival rates were 80.8 and 44.0%, respectively. As for conduit patency, two grafts (9.1%) demonstrated evidence of occlusion during long-term follow-up, but no additional interventions were required due to no complications related.

CONCLUSION

Our study, confirming data from existing literature, showed that the prosthetic reconstruction of the SVC system is a feasible additional procedure during resection of thymic tumor infiltrating the venous mediastinal axis, minimally increasing postoperative complications in experienced hands.

Reconstruction of mediastinal vessels for invasive thymoma: a retrospective analysis of 25 cases

BACKGROUND

Discuss an appropriate strategy for treatment of invasive thymoma invading adjacent great vessels.

METHODS

A retrospective study on 25 patients with invasive thymoma invading neighboring great vessels was performed. The corresponding data including clinical presentation, operation procedure, adjuvant radio-chemotherapy and follow-up were reviewed.

RESULTS

Twenty of 25 (80%) patients with invasive thymoma underwent complete resection of the tumor along with vessel reconstruction. Intraoperatively, different types of operation were conducted, namely, brachiocephalic vein (BCV)-right atrial appendage (RAA) reconstruction in 11 cases, complex vessel reconstruction (more than one graft) in 1 case and superior vena cava (SVC)-SVC reconstruction in the remaining cases. Ringed polytetrafluoroethylene (PTFE) grafts were used for vessel reconstruction. Postoperatively, three cases suffered from pulmonary infection, and three cases had haemothorax, chylothorax and atelectasis, respectively. Two patients died due to acute respiratory distress syndrome within 90 days after the surgery. Within the remaining patients, 11 cases (44%) experienced a relapse and finally 8 (32%) patients died. Compared to R1 resection group, R0 resection group had a better prognosis (Log-rank P=0.0196). The 3- and 5-year survival rates were 79.6% and 59.1%, with median survival time of 84 months.

CONCLUSIONS

Reconstruction of mediastinal vessels for invasive thymoma is a feasible technology method. Radical resection of the tumor with involved neighboring structures is the key to prolong overall survival for patients suffered from invasive thymoma.

Control of respiration-driven retrograde flow in the subdiaphragmatic venous return of the Fontan circulation

Respiration influences the subdiaphragmatic venous return in the total cavopulmonary connection (TCPC) of the Fontan circulation whereby both the inferior vena cava (IVC) and hepatic vein flows can experience retrograde motion. Controlling retrograde flows could improve patient outcomes. Using a patient-specific model within a Fontan mock circulatory system with respiration, we inserted a valve into the IVC to examine its effects on local hemodynamics while varying retrograde volumes by changing vascular impedances. A bovine valved conduit reduced IVC retrograde flow to within 3% of antegrade flow in all cases. The valve closed only under conditions supporting retrograde flow and its effects on local hemodynamics increased with larger retrograde volume. Liver and TCPC pressures improved only when the valve leaflets were closed whereas cycle-averaged pressures improved only slightly (<1 mm Hg). Increased pulmonary vascular resistance raised mean circulation pressures, but the valve functioned and cardiac output improved and stabilized. Power loss across the TCPC improved by 12%-15% (p < 0.05) with a valve. The effectiveness of valve therapy is dependent on patient vascular impedance.

Bovine valved jugular vein (Contegra™) to reconstruct the right ventricular outflow tract

The right ventricular outflow tract (RVOT) is the part of the circulation located between the right ventricle and the bifurcation of the pulmonary artery. The most cranial part of the right ventriculum infundibulum, the pulmonary anulus, the valve and finally the main trunk of the pulmonary artery are the most important structures. The RVOT is frequently affected in congenital heart diseases, either isolated, or in combination with other cardiac malformations. Current techniques for surgical correction of anomalies of the RVOT include repair and/or replacement of the pulmonary valve often combined with sub- or supravalvular reconstruction. The use of extracardiac conduits (homografts, stented or stentless xenografts) to re-establish continuity between the pulmonary ventricle and pulmonary artery has been an important advance in repair of complex congenital malformations. The Contegra (Medtronic) conduit was introduced as a xenograft tissue for RVOT reconstruction. This conduit has some advantages over homografts including availability for pediatric and adult patient sizes and proximal and distal cuffs allowing for extended reconstruction. The principal late problem related to extracardiac conduit operations is the inevitable need for one or more conduit replacements due to patient somatic growth or progressive conduit degeneration and calcification leading to stenosis.

Surgical outcomes after superior vena cava reconstruction with expanded polytetrafluoroethylene grafts

OBJECTIVES

Graft occlusion is a problem after superior vena cava (SVC) reconstruction for thoracic malignancy. Expanded polytetrafluoroethylene (ePTFE) is considered to be an optimal material for venous reconstruction.

METHODS

We reviewed the hospital records of 13 patients who underwent complete resection of thoracic malignancy invading the SVC, including SVC reconstruction with ePTFE grafts. Single bypass grafting was performed in two patients (one right-sided, one left-sided) and double bypasses grafting was performed in the other patients. All patients received antithrombotic therapy after surgery. Eight patients died of recurrence or other disease during the follow-up period (range 5-41 months).

RESULTS

Of the 24 grafts in 13 patients, graft patency was confirmed in 20 grafts in 9 patients at a mean time follow-up time of 47.8 ± 50.0 months after surgery. In the remaining four grafts in four patients, occlusion was diagnosed at a mean time of 1.25 ± 0.50 months after surgery. All obstructed grafts were left-sided bypass grafts in patients who underwent double bypass grafting, and did not result in SVC syndrome.

CONCLUSIONS

SVC reconstruction with ringed ePTFE grafts was safe and had good outcomes. In patients who underwent double bypasses grafting, the left-sided bypass grafts were susceptible to occlusion.

Superior vena cava bypass with cryopreserved ascending aorta allograft

Initially superior vena cava obstruction is typically managed by an endovascular approach. However, in some patients, particularly those in whom angioplasty and stenting is not technically possible, or those who have recurrent disease after previous endovascular repair, an open surgical approach may be indicated. Conduit choices for caval reconstruction are less than ideal; hence we describe a case using a cryopreserved aortic allograft.

Bovine valved xenograft (Contegra) conduit in the extracardiac Fontan procedure: the preliminary experience

OBJECTIVE

Constructing a competent valve using the xenograft valved conduit (Contegra) in the extracardiac Fontan connection may maintain better forward flow into the pulmonary circulation. The preliminary results and potential advantages of using the Contegra are discussed in this review.

METHOD

A retrospective review of 18 patients who underwent the extracardiac Fontan connection using the Contegra conduit from June 2002 to September 2005.

RESULTS

Median age at the time of operation was 4.5 year (range 2.5-34 years). In 15 patients (83%) a 4 mm fenestration was created. Overall operative mortality was 11 % (two patients); one patient died because of arrhythmia & sepsis, and the other one due to thrombosed Fontan connection. The ranges of intensive care unit stay, chest tube duration, and hospital stay were 1-18 days (median, 2 days), 4-38 days (median, 7 days), and 5-47 days (median, 12.5 days), respectively. Follow-up is available for 15 (94%) patients at a mean of 15.8 months (range 8-48 months) postoperatively. They were all asymptomatic and their room air oxygen saturation ranged between 88% and 100% (mean, 96.1%). There have been no further thromboembolic episodes during follow up. Echocardiograms demonstrated patent conduit in all patients with no hepatic vein reversal flow except to a minimal degree in five patients; however the valve competency was demonstrated radiologically.

CONCLUSIONS

The Contegra xenograft is a potential alternative conduit for the extracardiac Fontan connections. These encouraging preliminary results may support better pulmonary forward flow.

Thromboembolism and the role of anticoagulation in the Fontan patient

Among factors contributing to morbidity and failure of the Fontan circulation is the group of events referred to as thromboembolic complications. These events have been variously attributed to low flow states, stasis in the venous pathways, right-to-left shunts, blind cul-de-sacs, prosthetic material, atrial arrhythmias, and hypercoagulable states. Numerous investigations, most retrospective, have been undertaken to characterize thromboembolic events; describe the frequency and circumstances of these occurrences; and relate the risk of these events to patient, surgical, hemodynamic, and hematologic factors. Practices vary widely with respect to strategies of prophylactic anticoagulation in the hopes of minimizing the occurrence and morbidity of thromboembolism after Fontan operations. Review of the literature suggests that the factors associated with thromboembolic events after Fontan operations likely represent a complex field of biologic factors with multiple interactions. It is unlikely that a single agent will represent the solution to this complex problem.

Superior vena cava reconstruction using bovine jugular vein conduit

The glutaraldehyde-treated bovine jugular vein conduit (BJVC) is a xenograft conduit initially used for right ventricular outflow tract reconstruction and has never been used for reconstruction of superior vena cava (SVC). In September 2003, a patient with SVC obstruction underwent SVC reconstruction using BJVC. He has been alive for 42 months and free from signs and symptoms of SVC obstruction except that metastasis was found in the vertebrae. The radionuclide venography showed the graft tube was patent and only slight stenosis was found in the proximal anastomosis. The initial result supports BJVC as an acceptable alternative for SVC reconstruction.

Encouraging results for the Contegra conduit in the problematic right ventricle–to–pulmonary artery connection

OBJECTIVE

The Contegra conduit was developed for right ventricular outflow tract reconstruction. This report evaluates the Contegra conduit, with focus on certain subpopulations in which conduits are known to perform poorly (ie, patients with previous homograft conduits and infants).

METHODS

A retrospective review of 76 patients who had 77 Contegra conduits placed for right ventricular outflow tract reconstruction (January 2001 through August 2005) was completed. Characteristics include the following: median age of 1.6 years (range, 17 days-15.1 years), weight of 9.8 kg (range, 2.5-64.0 kg), and conduit diameter of 16 mm (range, 12-22 mm). Operations performed include right ventricular outflow tract reconstruction for pulmonary atresia-stenosis (n = 33), conduit exchange (n = 28), truncus repair (n = 7), primary conduit placement (n = 6), and the Ross procedure (n = 3). Seventy-nine percent were reoperations.

RESULTS

There was no hospital mortality. Mean follow-up was 20 +/- 14 months. One-, 2-, and 3- year freedom from severe conduit regurgitation was 97%, 86%, and 81%, respectively, and freedom from severe conduit stenosis was 100%. Freedom from reoperation for conduit failure at 1 and 3 years is 98.3% and 93.1%, respectively. All conduit failures (n = 3) were for asymptomatic conduit pseudoaneurysms in the setting of multiple-level pulmonary branch stenoses. Survival at 3 years is 96%. Infants (n = 26) had a freedom from Contegra conduit failure at 3 years of 100%. Patients with previous homograft conduits (n = 26) had a freedom from Contegra conduit failure at 3 years of 100%.

CONCLUSION

At midterm follow-up, the Contegra conduit remains a reliable, accessible, and easily implantable conduit for right ventricular outflow tract reconstruction. It appears to be the most promising conduit option for patients with previous homograft conduits and for infants.

Contegra conduit: current outcomes and concerns

A variety of congenital cardiac anomalies with severe right ventricular outflow tract (RVOT) obstruction or RVOT interruption require surgical reconstruction from the infundibulum up to the pulmonary artery bifurcation or even into the branches of the pulmonary arteries. Ideally, the conduit or valve required for such reconstruction has to be formed of autologous tissue that grows, resists infection, lasts for the life span of the patient and is readily available in all sizes. Such conduits, however, are not available and although several alternatives have been used, none of which are without potential drawbacks. Contegra valved bovine internal jugular vein conduit (Medtronic Inc., MN, USA) has recently emerged as a promising option for pediatric RVOT reconstruction and has been advocated for its 'off-the-shelf' availability in sizes ranging from 12 to 22 mm, surgical pliability and encouraging short- and mid-term success in experimental animal, as well as clinical studies. This review focuses on the current outcomes of Contegra conduit and highlights some of the major concerns related to the use of this conduit and strategies to tackle these concerns.

Adverse Mid-Term Outcome Following RVOT Reconstruction Using the Contegra Valved Bovine Jugular Vein

BACKGROUND

Current techniques for repair of the right ventricular outflow tract (RVOT) may require interposition of a valved conduit between the right ventricle and the pulmonary artery bifurcation. Recently, the Contegra conduit (Medtronic, Inc.) was introduced as an alternative xenograft tissue for RVOT reconstruction. Promising early hemodynamic and clinical results have been reported so far, but still less is known about mid-term adverse outcome.

METHODS

A total of 38 Contegra valved conduits (12 to 22 mm) were implanted from October 1999 to June 2004, in 36 children less than 5 years old and in 2 patients 8 and 21 years old. Diagnosis included the following: tetralogy of Fallot (n = 21); pulmonary atresia (n = 4); double outlet right ventricle + pulmonary stenosis (n = 3); d-transposition of the great arteries, ventricular septal defect, and pulmonary stenosis (n = 3); truncus arteriosus (n = 3); and other complex malformations (n = 4).

RESULTS

There was no mortality following initial surgery and no valved-conduit-related early morbidity. Early postoperative echocardiographic assessment after 3 months demonstrated favorable hemodynamics in all patients. However, during further follow-up, 5 conduits had to be replaced because of severe stenosis at the level of the distal anastomosis (2 of them had moderate to severe dilatation of the conduit proximally to the valve). Excessive intimal peel formation and severe perigraft scarring reaction were observed in all cases. One child died before surgery.

CONCLUSIONS

The Contegra valved conduit is an interesting concept for reconstruction of the RVOT. However, because of unpredictable incidence of supravalvar stenosis during mid-term results, we cannot recommend routine use of this material.

Congenital heart disease never goes away, even when it has been 'treated': the adult with congenital heart disease

PURPOSE OF REVIEW

As the specialties of pediatrics and pediatric cardiology continue to forge ahead with better diagnoses, medical care, and surgical results, an expanding population of patients with congenital heart disease (CHD) outgrows the pediatric age group, yet does not quite graduate to routine adult cardiology or general medicine. The adult with congenital heart disease (ACHD) faces medical, surgical, and psychosocial issues that are unique to this population and must be addressed as such. This review attempts to discuss and highlight some of the important advances and controversies brought up in the past year, in the care and management of these patients.

RECENT FINDINGS

The past five to 10 years have seen dynamic interest in understanding sequelae of corrected, uncorrected, or palliated congenital heart disease. The search for the ideal surgery, optimal prosthesis, and a smooth transition to adult care continues and is reflected in the vast amount of academic work and publications in this field. Of particular interest, conduit reoperations and single ventricle pathway modifications are still an art and a science in evolution.

SUMMARY

While all are agreed that there is a pressing need to focus on the delivery of care to the adult with congenital heart disease, this essentially requires a clearer understanding of late sequelae of CHD. The sheer heterogeneity of anatomy, age, surgery, and institutional management protocols can make it difficult to develop clear guidelines. This review attempts to give an up-to-date perspective on some of the new findings related to the more common lesions and problems faced in this group.

Right ventricular outflow tract reconstruction with the Contegra bovine jugular vein conduit: a word of caution

BACKGROUND

Since introduction in 1999, pulmonary valve replacement in pediatric patients with the Contegra conduit (Medtronic Inc, Minneapolis, MN) has gained widespread application with increasing enthusiasm. However, unexpected graft related adverse effects may occur.

METHODS

Between April 2001 and December 2002, 29 patients (20 male; mean age, 3.39 +/- 3.66 years; range, 0.01 to 13.0 years; mean weight, 11.62 +/- 8.73 kg) underwent right ventricular outflow tract reconstruction with the Contegra conduit. Seventeen patients underwent primary repair, 8 had prior homografts, and 4 had other previous operations.

RESULTS

There were no deaths. Three early graft related complications were observed. In two infants (age, 1.8 and 3.5 months; weight, 3.6 and 3.8 kg, respectively) thrombus formation at the conduit valve was detected 2 weeks postoperatively. Under anticoagulation with low-molecular-weight heparin, thrombi resolved completely in both patients. One patient (4.5 months, 4.43 kg) developed severe regurgitation due to a fibrous layer covering the inner conduit wall and required conduit exchange 3 weeks postoperatively. After a mean follow-up time of 10.2 +/- 6.4 months all patients are in good clinical condition. However, one patient with systemic right ventricular pressure developed pseudoaneurysm at both graft insertion sites and is scheduled for reoperation. Two other patients underwent balloon dilation. Freedom from reoperation and intervention at 1 year is 89.4%. With regard to regurgitation and conduit stenosis all other conduits perform well.

CONCLUSIONS

Contegra conduits are an alternative to homografts for right ventricular outflow tract reconstruction. However, there is a risk of thrombus formation in small infants so that prophylactic anticoagulation may be necessary. Patients with systemic right ventricular pressure require close observation as pseudoaneurysm formation has been observed.