Native Diaphragm Research Articles

Evaluation of a biodegradable polyurethane patch for repair of diaphragmatic hernia in a rat model: A pilot study

IntroductionCongenital diaphragmatic hernia (CDH) repair is an area of active research. Large defects requiring patches have a hernia recurrence rate of up to 50%. We designed a biodegradable polyurethane (PU)-based elastic patch that matches the mechanical properties of native diaphragm muscle. We compared the PU patch to a non-biodegradable Gore-Tex™ (polytetrafluoroethylene) patch. MethodsThe biodegradable polyurethane was synthesized from polycaprolactone, hexadiisocyanate and putrescine, and then processed into fibrous PU patches by electrospinning. Rats underwent 4 mm diaphragmatic hernia (DH) creation via laparotomy followed by immediate repair with Gore-Tex™ (n = 6) or PU (n = 6) patches. Six rats underwent sham laparotomy without DH creation/repair. Diaphragm function was evaluated by fluoroscopy at 1 and 4 weeks. At 4 weeks, animals underwent gross inspection for recurrence and histologic evaluation for inflammatory reaction to the patch materials. ResultsThere were no hernia recurrences in either cohort. Gore-Tex™ had limited diaphragm rise compared to sham at 4 weeks (1.3 mm vs 2.9 mm, p = 0.003), but no difference was found between PU and sham (1.7 mm vs 2.9 mm, p = 0.09). There were no differences between PU and Gore-Tex™ at any time point. Both patches formed an inflammatory capsule, with similar thicknesses between cohorts on the abdominal (Gore-Tex™ 0.07 mm vs. PU 0.13 mm, p = 0.39) and thoracic (Gore-Tex™ 0.3 mm vs. PU 0.6 mm, p = 0.09) sides. ConclusionThe biodegradable PU patch allowed for similar diaphragmatic excursion compared to control animals. There were similar inflammatory responses to both patches. Further work is needed to evaluate long-term functional outcomes and further optimize the properties of the novel PU patch in vitro and in vivo. Level of evidenceLevel II, Prospective Comparative Study.

Diaphragmatic Flap: Technique of Preparation and Indications for Use

Background: The use of a vascularized pedicle flap of diaphragmatic muscle (DF) for reconstructive procedures in the chest has many advantages. Yet, despite the excellent reported results, the use of DF has not been widespread. Some factors for the less widespread use of DF have been, concern about diaphragmatic function, hesitation to use such a vital muscle for reconstructive purposes, and most importantly, the technical aspects for the preparation of the flap. Methods: Using a cadaveric model, the vascular anatomy of the diaphragm and the steps for the preparation of the DF was defined and illustrated for both the right and left hemidiaphragm. Results: No perioperative mortality with the use of DF has been recorded. Function of the native diaphragm has not been impaired. Bronchopleural fistulas and pericardial defects have healed in all instances. Excellent repair has been achieved in all patients with esophageal lesions. The disruption of the repaired native diaphragm and visceral herniation has been reported but it has been attributed to the learning curve and the technique of repair. Conclusion: With a better understanding of the vascular anatomy of the diaphragm and a formal methodical approach to harvesting the DF, more surgeons will be encouraged to use DF with excellent results.

Bubaline Diaphragm Matrix: Development and Clinical Assessment into Cattle Abdominal Hernia Repair

Abstract The purpose of the study was to develop a xenogenic bubaline diaphragm matrix (BDM) for abdominal hernia repair. A fresh diaphragm was decellularized using aqueous sodium dodecyl sulfate (SDS) solutions (0.5-4% w/v) over a period. Acellularity was confirmed histologically and characterized by Masson’s trichrome staining, scanning electron microscopy (SEM), DNA quantification, agarose gel electrophoresis, and Fourier-transform infrared spectroscopy. The BDM was used for clinical abdominal hernia repair in six cattle. Clinical, hemato-biochemical and antioxidant parameters were evaluated to assess biocompatibility of xenogenic BDM. Histologically, the diaphragm treated with 2% SDS for 48 h showed complete acellularity and orderly arranged collagen fibers. The SEM confirmed preservation of collagen structure and integrity. The DNA content was significantly (P < 0.05) reduced in BDM (33.12 ± 5.40 ng/mg) as compared to the native diaphragm (443.96 ± 162.60 ng/mg). DNA extracts from BDM show considerable removal of DNA material, with absence of DNA band in agarose gel. The FTIR spectrum of BDM has shown all characteristic transmittance peaks of bovine skin collagen indicating preserved collagen structure. Six cattle with BDM implant recovered uneventfully and remained sound at least upto 6 months. Hemato-biochemical and antioxidant findings were unremarkable. Bubaline diaphragm matrix shows excellent repair efficiency and biocompatibility for abdominal hernia repair in cattle without complications.

Engineering and repair of diaphragm using biosheet (a collagenous connective tissue membrane) in rabbits

BackgroundProsthetic patches can be used to repair large congenital diaphragmatic hernia defects but may be associated with infection, recurrence, and thoracic deformity. Biosheets (collagenous connective tissue membranes) have been used in regenerative medicine. We evaluated the efficacy of Biosheets in a rabbit model. MethodsBiosheets were prepared by embedding silicone plates in dorsal subcutaneous pouches of rabbits for 4weeks. In group 1 (n=11), Gore-Tex® sheets (1.8×1.8cm) were implanted into a diaphragmatic defect. In group 2 (n=11), Seamdura®, a bioabsorbable artificial dural substitute, was implanted in the same manner. In group 3 (n=14), biosheets were autologously transplanted into the diaphragmatic defects. All rabbits were euthanized 3months after transplantation to evaluate their graft status. ResultsHerniation of liver was observed in 5 rabbits (45%) in group 1, 8 (73%) in group 2, and 3 (21%) in group 3. A significant difference was noted between groups 2 and 3 (P=0.017). Biosheets had equivalent burst strength and modulus of elasticity as native diaphragm. Muscular tissue regeneration in transplanted biosheets in group 3 was confirmed histologically. ConclusionBiosheets may be applied to diaphragmatic repair and replacement of diaphragmatic muscular tissue. Level of evidenceLevel III.

Fascicular Phrenic Nerve Neurotization for Restoring Physiological Motion in a Congenital Diaphragmatic Hernia Reconstruction With a Reverse Innervated Latissimus Dorsi Muscle Flap

Congenital diaphragmatic hernia is a severe developmental anomaly characterized by the malformation of the diaphragm. An innervated reversed latissimus dorsi flap reconstruction for recurrent congenital diaphragmatic hernia has been described as an alternative to prosthetic patch repair to achieve pleuroperitoneal separation. However, there is very little supporting scientific data; therefore, there is no real basic understanding of the condition of the phrenic nerve in the absence of diaphragmatic muscle or even the neurotization options for restoring neodiaphragmatic muscle motion. We have reviewed the literature regarding phrenic nerve anatomy and neurotization options, and to our knowledge, this is the first time that the application of a fascicular repair is being described where the continuity of one remaining fascicle of the diaphragm has been preserved close to the phrenic nerve distal division. The procedure was undertaken in a 3 year-old boy, with the diagnosis of congenital large posteromedial diaphragmatic hernia and dependence of mechanical ventilation in consequence of severe bronchopulmonary dysplasia.The phrenic nerve divides itself into several terminal branches, usually three, at the diaphragm level, or just above it. This allows the selective coaptation of separate fascicular branches. In the case described, videofluoroscopy evaluation showed no evidence of paradoxical neodiaphragmatic motion, with synchronous contraction movements and intact pleura-peritoneal separation. The child is now asymptomatic and shows improvement of his previous restrictive pulmonary disease.We believe that fascicular repair can achieve some reinnervation of the flap without jeopardizing the potential of diaphragmatic function by contraction of reminiscent native diaphragm.

PC.02 Tissue engineering approach with acellular matrix supports affected diaphragm of an atrophic mouse model with activation of resident cells

Myopathies are frequently caused by mutations in genes encoding for extracellular matrix (ECM) proteins, which gets progressively substituted by fibrotic tissue. Spinal muscular atrophy is a disorder caused by mutations...

10.5 Tissue engineering approach with acellular matrix supports affected diaphragm of an atrophic mouse model with activation of resident cells

Myopathies are frequently caused by mutations in genes encoding for extracellular matrix (ECM) proteins, which gets progressively substituted by fibrotic tissue. Spinal muscular atrophy is a disorder caused by mutations...

A newly designed bioabsorbable substitute for the treatment of diaphragmatic defects

Earlier studies have investigated the suitability of various materials and autologous grafts for the repair of diaphragmatic defects. Our group investigated the feasibility of using an artificial diaphragm (AD) to repair wide diaphragmatic defects. Twelve pigs were laparotomized and, in each pig, a defect was fashioned by resecting a round 8-cm diameter hole in the left diaphragm. Next, the defect was repaired by implanting an AD. The animals were relaparotomized 8 or 24 weeks after implantation for gross, histological and radiological observation of the implanted sites. All recipient animals survived until killing for evaluation. Chest X-ray examinations showed no differences between the preoperative diaphragms and the grafted diaphragms at 8 and 24 weeks after implantation. At 8 weeks after implantation, the implanted sites exhibited fibrous adhesions to the liver and lungs without deformities or penetrations. Parts of the surface tissue at the graft sites had a varnished appearance similar to those of the native diaphragm. Histology performed at 8 weeks detected no trace of the ADs in the graft sites; however, numerous inflammatory cells and profuse fibrous connective tissue were observed. At 24 weeks after implantation, no differences were found in the thorax between the areas with the grafts and the unaffected areas. Histology of the graft sites in the thorax confirmed growth of mesothelial cells similar to that observed in the native diaphragm. Artificial diaphragms can be a novel substitute for diaphragmatic repair.

The whole truth: comparative analysis of diaphragmatic hernia repair using 4-ply vs 8-ply small intestinal submucosa in a growing animal model

Background Diaphragmatic reconstruction remains a challenging problem. There is limited information concerning the use of small intestinal submucosa (SIS) in congenital diaphragmatic hernia repair. A canine model was used to evaluate the use of a SIS patch in diaphragmatic reconstruction. Methods Eleven beagle puppies (1.6-4.2 kg, 8 weeks old) underwent left subcostal laparotomy, central left hemidiaphragm excision (2 × 7 cm, 50% loss), and reconstruction with a 4-ply group I (n = 5) or 8-ply group II (n = 6) SIS patch. Chest radiographs were taken at time of operation and 3 and 6 months postoperatively. Animals were killed at 6 months. Adhesion formation (both pleural and abdominal), gross visual evaluation of the patch, and histology were compared. Results In group I (4-ply), 1 animal died at 3 months from patch deterioration accompanied by stomach herniation that resulted in respiratory failure. In the 4 remaining animals, chest radiographs showed no evidence of herniation or eventration. On physical examination, there was no evidence of chest wall deformity. During gross surgical examination, the 4-ply patches showed thinning, multiple defects, and liver herniation in 3 animals. In 1 pup, the patch was thickened, intact, well incorporated at the repair site, and adherent to the liver and spleen. In group II (8-ply), 1 animal died of cardiopulmonary failure in the early postoperative period. In the other 5 animals, chest radiographs showed evidence of eventration in 1. On gross examination the patch adhered to the liver in all 5 surviving animals. In 4, the patches were thickened, viable, but had some shrinkage. One patch pulled away from the native diaphragm laterally; however, no visceral herniation was present. In the 1 animal with eventration, there was no evidence of a patch. Adhesion scores (AS) were graded and determined by the sum of extent (0-4), type (0-4), and tenacity (0-3). Average abdominal AS in group I was 5.6 ± 0.8 vs 10.2 ± 0.2 ( P = .079) for group II. Average lung AS was 0.6 ± 0.6 in group I vs 3.8 ± 1.1 ( P = .0476) for group II. Histological examination showed group II patches had greater collagen deposition with central calcification and mild inflammation within the residual graft, whereas group I patches were much thinner and were composed of granulation tissue without evidence of residual graft. Conclusions These data indicate that 8-ply SIS repair of diaphragmatic defects was superior (80%; 4/5 to 4-ply, 20%; 1/5, success). Organ adherence appears to be necessary for neovascularization of the SIS composite. Eight-ply grafts appear to be more durable and persist for a longer period, which may improve neovascularization. Long-term follow-up to evaluate remodeling characteristics of the patch material is required.

Reconstruction of congenital agenesis of hemidiaphragm by combined reverse latissimus dorsi and serratus anterior muscle flaps

Background/Purpose: Diaphragmatic agenesis (DA) is a distinct clinical entity with poorer survival rate compared with patients with posterolateral diaphragmatic hernia. The large defect in DA is repaired frequently with a synthetic patch in the neonatal period. Well-known, long-term complications include recurrent hernia caused by patch dislodgement, chest wall deformation caused by noncompliant patch, and deteriorating pulmonary function. A reverse latissimus dorsi flap (RLD) allows continued growth of the reconstructed diaphragm with an intact pleuro peritoneal separation. When combined with neuroanastomosis of the phrenic and thoracodorsal nerves it has the potential to function as a native diaphragm. Incorporation of Serratus anterior (SA) muscle enables reconstruction of larger defects. Methods: Two cases of DA are presented. In each case the primary SILASTIC® (Dow Corning, Midland, MI) patch repair failed and was replaced successfully with a RLD flap reconstruction with or without incorporation of SA and neuroanastomosis. Results: Both patients recovered from surgery with minimal morbidity. The reconstructed diaphragm is intact at long-term follow-up. There is marked improvement of growth of the infants, respiratory difficulties, and chest wall deformity. Conclusions: This technique is recommended in DA when the synthetic patch fails. J Pediatr Surg 36:1637-1640. Copyright © 2001 by W.B. Saunders Company.

Short-term absorbable material for diaphragmatic replacement

To evaluate absorbable materials for use for replacement of the diaphragm, we implanted materials in experimentally-created diaphragmatic defects in pigs. As a short-term absorbable material, bovine serosa (BS) was used. Its absorption was complete after 4-6 weeks. In a control group, the defect was repaired with a continuous running polypropylene suture. In two other groups the defect was closed with lyophilized dura (LD) and a modified transverse abdominal muscle flap according to Hecker, respectively. Physical studies (load capacity and elasticity) and histologic investigations were performed in one-half of the animals of each group after 3 and 6 months, respectively. Considering their physical properties, it could be shown that all materials tested are suitable for replacement of the diaphragm, but that BS best resembled native diaphragm. We conclude that short-term absorbable BS is suitable for replacement of the diaphragm in pigs.

Diaphragm replacement: An experimental animal study

We performed an open experimental study for evaluation of rapidly absorbable material of bovine serosa for diaphragm replacement. A total of 100 Sprague-Dawley rats were randomly assigned to five groups of equal size. In the control group (n=20) incision of the diaphragm was followed by primary suture. The animals of the four other groups underwent partial resection of the left hemidiaphragm. The defects were repaired by lyophilized dura, polytetrafluorethylene (PTFE), autologous transversus muscle or rapidly absorbable bovine serosa. We performed electromyography (EMG) and postmortem physical examinations of elasticity and load capacity of the different materials as well as histologic examinations after three and six months. A total of 89 animals survived and were subject to the analysis. There were no differences between the groups concerning growth and weight gain. The EMG showed normal function for the absorbable material and the transversus muscle. Only scanty physiologic waves were registered in the PTFE group. Load capacity measurements showed the lowest value of 4.71 N for the native diaphragm; all other materials had much higher values (17.66 N – 51.99 N) with a peak load capacity in the PTFE group. Measurements of elasticity displayed similar results. The native diaphragm had the lowest value (1516 N/m); much higher values were found in all the other materials tested (3905 N/m – 7654 N/m) with again peak values for PTFE. The differences of all materials compared to native diaphragm were statistically significant (p<0.05). The histologic examinations revealed strong foreign body reactions in the dura and PTFE groups. The absorbable bovine serosa had vanished three months postoperatively. Short-term absorbable bovine serosa tested successfully as a partial replacement of the diaphragm in this experimental study on rats. There may be additional indications for this material if a temperary replacement is intended.