Sudesh Prabhu

Histologic Evaluation of Explanted Tissue-Engineered Bovine Pericardium (CardioCel)

CardioCel is a bovine pericardium that is subjected to a novel anticalcification tissue-engineering process. We present the histopathologic findings of human explants of CardioCel that were used in operations for congenital heart disease in children. Six explants were identified from 140 patients undergoing CardioCel implants from October 2012 to March 2015. CardioCel explants were evaluated histologically using hematoxylin and eosin, Masson trichrome, and immunohistochemical staining. A variable inflammatory response was seen in the surrounding native tissue, but not within the CardioCel graft in any of the explants. A neointimal layer of varying thickness developed on the visceral surface of 5 CardioCel explants with endothelialization of the longest duration explant. A granulation tissue layer developed on the parietal surface of the graft (consistently thicker than the neointima). Maintained collagen fiber architecture (laminated) and variable fibroblastic invasion (which increased with the age of the implant) were identified in all 6 cases. Scattered capillary vessels were noted in the majority of the explants with new collagen fibers in one, suggesting early remodeling. Calcium was seen in 1 explant at the interface of the graft and inflammatory response on its parietal surface. Evidence of graft remodeling was noted in the majority of the explants without inflammatory cells or calcification within the explanted graft material. A noticeable feature was the differential thickness of the host reaction to the parietal compared with the visceral surface of the graft. We will continue to evaluate CardioCel as a cardiovascular substitute for extracardiac and intracardiac reconstructions.

A Simplified Technique for Interventional Extracardiac Fontan

Purpose: We report a simple technique for an interventional extracardiac Fontan (ECF) procedure. Description: At the preparatory stage along with a bidirectional cavopulmonary connection (BCPC; cardiopulmonary bypass), a short piece of polytetrafluoroethylene (PTFE) tube graft is anastomosed to the inferior surface of the right pulmonary artery. Another longer PTFE graft is anastomosed to the transected inferior vena cava (IVC). A large medial opening in the lower PTFE graft is anastomosed to an atriotomy. These two PTFE tubes are anastomosed with a pericardial patch interposed between them. During the later interventional Fontan procedure, this pericardial patch is perforated using radiofrequency, and a covered stent is positioned entirely within the PTFE tubes, eliminating the window into the common atrium and leaving no intrapulmonary prosthetic material. Evaluation: The hemodynamics after the preparatory stage is similar to those following a BCPC, with uninterrupted flow from the IVC to the right atrium. On completion, there is a nonfenestrated Fontan circuit. Conclusion: Our technique of interventional Fontan, anatomically and hemodynamically, mimics a standard ECF procedure.

Repair of congenital diaphragmatic hernia during extracorporeal life support: experience with six neonates

Background The management of congenital diaphragmatic hernia (CDH) in neonates has evolved considerably over the last three decades. Initial stabilization followed by surgical repair is the current standard of care. A subset fails to achieve adequate oxygenation with medical management, including the use of high frequency oscillation and inhaled nitric oxide. The mortality in this group exceeds 80% without additional management strategies. Extracorporeal life support (ECLS) is a well-established modality for managing these neonates with CDH and has been shown to improve early survival in selected cases. Methods This is a retrospective analysis of six neonates with CDH who underwent repair during ECLS between September 2011 and November 2014. Results Of 24 admissions with CDH, there were six neonates (25%) who required ECLS. All the six had CDH repair during ECLS. There were no intra-operative bleeding complications. There were no clotting complications related to stopping heparin during CDH repair. There was one hospital death. Five neonates were weaned from ECLS and discharged home. Conclusions Data from our small cohort of patients illustrate that early survival is possible in extremely compromised neonates who otherwise would have died without ECLS. Our experience demonstrates that CDH repair can safely be performed during ECLS. Use of ECLS, early repair during ECLS, lung protective ventilation strategies and aggressive management of pulmonary hypertension were associated with good early survival. ECLS should be considered as an integral part of therapeutic armamentarium for CDH in neonates.The management of congenital diaphragmatic hernia (CDH) in neonates has evolved considerably over the last three decades. Initial stabilization followed by surgical repair is the current standard of care. A subset fails to achieve adequate oxygenation with medical management, including the use of high frequency oscillation and inhaled nitric oxide. The mortality in this group exceeds 80% without additional management strategies. Extracorporeal life support (ECLS) is a well‐established modality for managing these neonates with CDH and has been shown to improve early survival in selected cases.

Extracorporeal life support in multisystem smooth muscle dysfunction syndrome

We describe an infant with congenital mydriasis, patent ductus arteriosus (PDA), pulmonary hypertension, and cystic lung disease. She had all the major components of multisystemic smooth muscle dysfunction syndrome. Due to progressive respiratory deterioration, she required surgical PDA interruption, extracorporeal life support, and subsequent prolonged respiratory support. Genetic testing revealed ACTA2 R179H mutation and cystic lung disease on biopsy.

Mosaic 22q11.2 deletion and tetralogy of Fallot with absent pulmonary valve: an unreported association

Chromosome 22q11.2 microdeletion is the most common microdeletion syndrome. Mosaic 22q11.2 deletions are very rare and only a few have been reported. We describe a case of a neonate with tetralogy of Fallot with absent pulmonary valve with mosaic 22q11.2 deletion. Fluorescent in situ hybridization analysis of lymphocytes showed a hemizygous 22q11.2 microdeletion in 66% of interphase nuclei. Microarray testing confirmed a 1.66 Mb deletion at 22q11.2. The child did not have any clinical manifestations of 22q11.2 deletion other than the cardiac malformation.

Interposition of aortic valve leaflets for reinforcement of Bentall proximal anastomosis

Bleeding from the proximal suture line is not uncommon after composite graft anastomosis in the Bentall procedure. The passage of valve sutures through the aortic valve leaflets interposed between the pledgets and the cuff of the composite valved conduit strengthens the repair.

Durability of tissue-engineered bovine pericardium (CardioCel®) for a minimum of 24 months when used for the repair of congenital heart defects

OBJECTIVES This study aims to assess the performance of tissue-engineered bovine pericardium (CardioCel®) at 24 months and beyond when used for the repair of congenital heart defects. METHODS Between October 2012 and November 2014, CardioCel was implanted in 135 patients (140 procedures and 195 implants). Applications included the closure of septal defects (98, 50.3%), repair of pulmonary arteries (63, 32.3%), intra-atrial/intraventricular baffles (10, 5.1%), repair of systemic arteries (15, 7.7%), valve repair (5, 2.6%), repair of systemic veins (3, 1.5%) and Fontan operation (1, 0.5%). There were 19 (13.6%) procedures performed in neonates, 77 (55%) in infants and 44 (31.4%) in children older than 365 days. RESULTS Eight patients (n = 135, 5.9%) required reintervention in 12 instances (n = 195, 6.2%, 6 catheters and 6 surgical). There was no echocardiographic or radiological evidence of calcification in any patient. Ten of the reinterventions (83%) occurred within the first 12 months. All the reinterventions occurred within 36 months. Freedom from reintervention at both 12 and 24 months was 95% [confidence interval (CI) 91-97] and at 36 months was 94% (CI 89-97). There was no statistical difference in freedom from reintervention when stratified by age or patch position. CONCLUSIONS At 24 months and beyond the follow-up, the performance of CardioCel remains acceptable with good haemodynamic performance. There was no echocardiographic or radiological evidence of calcification in any patient. CardioCel performs comparably in systemic and pulmonary circulations.

Long-term performance of homografts versus stented bioprosthetic valves in the pulmonary position in patients aged 10-20 years

OBJECTIVES We aimed to compare the long-term performance of pulmonary homografts and stented bioprosthetic valves in the pulmonary position in patients aged 10-20 years. METHODS Between January 1995 and December 2015, 188 patients aged 10-20 years undergoing pulmonary valve replacement were identified retrospectively from hospital databases in both congenital cardiac centres in Brisbane. Valve performance was evaluated using previously described standard criteria. Propensity score matching was used to balance the 2 treatment groups. RESULTS Freedom from structural valve degeneration in homografts (n = 131) was 97%, 92% and 85% at 3, 5 and 10 years, respectively, and 91% and 53% at 3 and 5 years, respectively, in the bioprosthesis group (n = 57). Freedom from reintervention in homografts was 96%, 93% and 88% at 3, 5 and 10 years, respectively, and 93% and 68% at 3 and 5 years, respectively, in the bioprosthesis group. The unadjusted Cox regression analysis demonstrated that a bioprosthesis was at 5.64 times the risk of structural valve degeneration and 3.89 times the risk of reintervention. The Cox regression analysis performed on the propensity matched sample (45 pairs of patients) revealed that a bioprosthesis was at almost 10 times the risk of experiencing structural valve degeneration [hazard ratio (HR) = 9.18] and at more than 8 times the risk of undergoing a reintervention (HR = 8.34). CONCLUSIONS In our patient population, pulmonary homografts outperformed stented bioprosthetic valves within 5 years when implanted in the pulmonary position in patients aged 10-20 years. We recommend the use of a pulmonary homograft for pulmonary valve replacement in this age group in patients undergoing surgery for congenital heart disease.

Temporary Single Ventricle Palliation for Severe Diastolic Dysfunction in a Biventricular Heart

We describe a neonate with severe left ventricular (LV) dysfunction manifesting soon after birth, who required extracorporeal life support (ECLS). Multiple attempts at separation from ECLS resulted in high left atrial pressures and hemorrhagic pulmonary edema. The inability to separate from ECLS after ten days prompted an unconventional treatment strategy. We performed a modified Norwood operation for LV rehabilitation on day 10 of ECLS. This was followed by successful separation from ECLS. Left ventricular function recovered, and the child underwent conversion to a biventricular circulation on 128 days post-Norwood.

Anticoagulation for Interventional Extracardiac Fontan

I read with great interest the article written by Prabhu et al published in World Journal for Pediatric and Congenital Heart Surgery entitled “A Simplified Technique for Interventional Extracardiac Fontan.” The Fontan operation is currently reported to have a tenyear survival of up to 94%. On the other hand, one of the major causes of morbidity and mortality after the Fontan operation is thromboembolic events (TEs), and different studies report varying incidence of thrombosis and embolism ranging from 4% to 20%. It is attributed to low flow states, stasis in venous pathways, right to left shunts, blind cul-de-sacs, prosthetic materials, atrial arrhythmias, and hypercoagulable states. Moreover, a randomized trial of 111 patients who had undergone extracardiac total cavo-pulmonary connection (TCPC) showed higher incidence of TE. According to the article, the authors have described a new method that simplified the total cavopulmonary connection without surgical approach using two separate polytetrafluoroethylene (PTFE) grafts. The two grafts have been divided by autologous pericardium to close the top end of the inferior PTFE graft resulting in a stump above the level of fenestration. In the presence that stump, wouldn’t the likelihood of clot formation and TE, which is a possibility that should never be ignored, increase, especially in the presence of large connection between right and left atrium? What kind of anticoagulation should we use to prevent clot formation?