Use of Indigenous Decellularized Valved Xenograft Conduit for Double-Barrel Right Ventricular Outflow Tract Reconstruction: Nine-Year Follow-Up

[Methods of surgical reconstruction of the conjunctiva]

Reconstruction of the conjunctiva is required for restoration of damaged ocular surface and is an essential part of that process. Traumas, chemical and thermal burns, multiple surgical intervention can seriously damage the integrity of conjunctival tissue and promote the growth of fibrous tissue, scarring of contractures and their shortening, as well as other complications such as trichiasis, erosion and ulcers on the cornea. When a larger area is affected, there may not be enough donor tissue to replace the defect, in which case the tissue grafts are required to be large enough. Modern modifications of surgical techniques and the continued development of tissue engineering, as well as advancements in stem cell research offer promising novel alternatives for solution of those problems. This article reviews the existing surgical methods of conjunctival reconstruction.

Primary repair of transposition of the great arteries with an interrupted aortic arch: a case report and literature review

Transposition of the great arteries (TGA) and interruption of the aortic arch (IAA) are uncommon congenital heart diseases. The association between TGA and IAA is rare. The aim of this study is to present a case with combined TGA and IAA, who underwent the primary repair and review the literature with similar cases. The one-month-old patient was admitted with tachypnea and cyanosis. Delayed diagnosis was caused due to the absence of prenatal examination. Echocardiography and computed tomography angiography confirmed TGA with anterior-posterior-oriented great arteries, wide patent ductus arteriosus, type B IAA, ventricular septal defect (VSD) and pulmonary arterial hypertension. The patient underwent a single-stage primary surgical repair process leading to VSD closure, reconstruction of the aortic arch and arterial switch operation in October 2019. The patient is doing well at a 3-month follow-up post-surgery. The echocardiogram suggests a normal systolic function of the ventricles and trivial regurgitation for both aortic and pulmonary valves. CONCLUSIONS: The single-stage repair with VSD closure, reconstruction of aortic arch and arterial switch operation might be an applicable approach for most of the patients with combined TGA and IAA. Long term follow-up is required as a high re-intervention rate for recurrent coarctation, supravalvular aortic stenosis, neoaortic valve regurgitation, obstruction of the right heart system and coronary stenosis has been reported.

Adult tetralogy repair: factors affecting early outcome in the current era

Background

The benefits of surgical correction of adult tetralogy of Fallot are well known. The current recommendation is for total correction regardless of age. This study analyzed perioperative factors affecting early outcome after corrective surgery in adulthood in the current era.

Methods

This was a retrospective chart review of 40 consecutive patients over 18 years of age who underwent total correction of tetralogy of Fallot from September 2006 to June 2013. Patients with pulmonary atresia and absent pulmonary valve were excluded. The mean age at surgery was 26.60 ± 8.69 years (range 18–49 years).

Results

The mean intensive care unit stay was 3.30 ± 2.29 days (range 0.75–12 days) and hospital stay was 9.97 ± 3.39 days (range 7–22 days). Mortality was 5% (2/40). Multiple parameters indicating immediate postoperative outcomes and their relationships to selected pre-, intra-, and postoperative factors were analyzed. Multivariate analysis showed that postoperative right ventricular dysfunction had a significant influence on mortality ( p < 0.001) and hospital stay ( p = 0.01). Performing zero-balance ultrafiltration decreased the need for renal replacement therapy ( p = 0.034), duration of ventilation ( p = 0.009), incidence of low cardiac output ( p = 0.006), intensive care unit stay ( p = 0.01), and hospital stay ( p = 0.009).

Conclusions

Total correction of tetralogy of Fallot is a safe option for presentations as late as adulthood. The protective effect of zero-balance ultrafiltration on postoperative morbidity needs to be reassessed in larger studies.

Decellularised conjunctiva for ocular surface reconstruction

Conjunctival reconstruction is an integral component of ocular surface restoration. Decellularised tissues are frequently used clinically for tissue engineering. This study identifies porcine decellularised conjunctiva (PDC) and human decellularised conjunctiva (HDC) as promising substitutes for conjunctival reconstruction. PDC and HDC were nearly DNA-free, structurally intact and showed no cytotoxic effects in vitro, which was confirmed by DNA quantification, histology, transmission electron microscopy, collagen quantification and cytotoxicity assay. Comparing the biomechanical properties to amniotic membrane (AM), the most frequently applied matrix for ocular surface reconstruction today, the decellularised conjunctiva was more extensible and elastic but exhibited less tensile strength. The in vivo application in a rabbit model proofed significantly enhanced transplant stability and less suture losses comparing PDC and HDC to AM while none of the matrices induced considerable inflammation. Ten days after implantation, all PDC, 4 of 6 HDC but none of the AM transplants were completely integrated into the recipient conjunctiva with a partially multi-layered epithelium. Altogether, decellularised conjunctivas of porcine and human origin were superior to AM for conjunctival reconstruction after xenogeneic application in vivo.

STATEMENT OF SIGNIFICANCE

Conjunctival integrity is essential for a healthy ocular surface and clear vision. Its reconstruction is required in case of immunological diseases, after trauma, chemical or thermal burns or surgery involving the conjunctiva. Due to limitations of currently used substitute tissues such as amniotic membrane, there is a need for the development of new matrices for conjunctival reconstruction. Decellularised tissues are frequently applied clinically for tissue engineering. The present study identifies porcine and human decellularised conjunctiva as biocompatible and well tolerated scaffolds with superior integration into the recipient conjunctiva compared to amniotic membrane. Decellularised conjunctiva depicts a promising substitute for conjunctival reconstruction in ophthalmology.

[New approaches to ocular surface reconstruction beyond the cornea]

BACKGROUND

Reconstruction of the conjunctiva is an essential part of ocular surface reconstruction. Clinically applied and experimentally tested tissue- and stem-cell-based approaches are presented and evaluated.

MATERIALS AND METHODS

Current literature and our own results will be presented.

RESULTS

Autologous conjunctiva, mucous membrane of the mouth or nose, and amniotic membrane are routinely used for conjunctival reconstruction. Limitations are limited availability, involvement in autoimmune diseases, donor heterogeneity, and degradation in an inflamed environment. Experimentally tested matrices as tissues made from extracellular matrix proteins, synthetic polymers, temperature-sensitive culture dishes, and decellularized conjunctiva have been tested in vitro and partly in vivo. To replace conjunctival cells, cells of conjunctiva and mucous membrane of mouth and nose have been evaluated and show progenitor cell properties as well as secretory capacity (goblet cell differentiation).

CONCLUSIONS

Although different matrices are available for conjunctival reconstruction there is-due to specific limitations of existing tissues-a need for the development of new therapies for conjunctival replacement. Matrices produced in the laboratory have already been partly investigated in vivo and may thus be clinically applicable in the near future. Adult mucous membrane cells show many properties of conjunctival epithelium after expansion in vitro and thus are a promising cell source for conjunctival tissue engineering. Other stem cells sources require further evaluation.