The use of epoxy patch grafts for the repair of experimentally-created diaphragmatic defects in dogs

Diaphragmatic hernia repair using a rectus abdominis muscle pedicle flap in three dogs

Objective: To report the clinical use of a pedicle flap from the rectus abdominis muscle to repair extensive diaphragmatic tears in dogs with diaphragmatic hernia.

Materials and methods: Three dogs with a combination of radial and circumferential diaphragmatic tears were studied. The circumferential tear was repaired by suturing the wound edge with the edge at the abdominal wall. A pedicle flap of the rectus abdominis muscle was used for repairing the radial tear. The dogs were examined radiographically for lung and diaphragm appearance and evidence of reherniation at 10 days, and at one, two, and four months after surgery, and fluoroscopically for paradoxical motion of the diaphragm at one and four months.

Results: The rectus abdominis muscle pedicle flap was successfully used in all three dogs. The animals recovered uneventfully without evidence of reherniation during the four follow-up months. Fluoroscopic examination revealed no paradoxical motion of the diaphragm.

Clinical significance: A rectus abdominis muscle pedicle flap can be used for repairing large diaphragmatic defects in dogs.

Hernioplastia diafragmática em cão com pericárdio bovino conservado em solução supersaturada de açúcar

Foram utilizados sete cães adultos, três machos e quatro fêmeas, sem raça definida, com pesos entre 10 e 22kg, para avaliação do processo cicatricial do músculo diafragma, na presença do implante de pericárdio bovino conservado em solução supersaturada de açúcar a 300%. Foi criado um defeito na porção muscular do hemidiafragma esquerdo de dimensões 8,0×5,0cm. Após a toracotomia no oitavo espaço intercostal esquerdo, o implante heterógeno foi fixado com fio poliamida nº 3-0 por meio de sutura simples contínua. Decorrido o período pré-estabelecido de pós-operatório, os animais foram submetidos a exames radiográficos simples e contrastado e a estudos macroscópico e histológico. Na avaliação radiográfica, foi verificada presença das silhuetas diafragmática e cardíaca, sem evidências de vísceras abdominais no interior do tórax. Macroscopicamente, notou-se a formação de tecido conjuntivo fibroso semi-transparente que ocluia o defeito diafragmático. O segmento de pericárdio bovino conservado em solução supersaturada de açúcar a 300%, em temperatura ambiente, é substituído por uma fina camada de tecido conjuntivo fibroso e promove a restauração do defeito no músculo diafragma de cão.

Comparison of extracapillary and endocapillary blood flow oxygenators for open heart surgery in dogs: efficiency of gas exchange and platelet conservation

The goal of the current study was to compare the efficiency of gas exchange and platelet conservation of a new extracapillary blood flow oxygenator versus an endocapillary blood flow oxygenator during open heart surgery with extracorporeal circulation in dogs. Dilation and remodeling of the right ventricular outflow tract of dogs was performed using a patch graft technique to simulate pulmonary stenosis. Sequential pre- and post-operative blood analysis revealed that gas exchange efficiency and platelet conservation was significantly greater with the extracapillary blood flow oxygenator than with the endocapillary blood flow oxygenator. However, the priming volume of the extracapillary blood flow oxygenator was significantly greater, leading to hemodilution. We conclude that while the extracapillary blood flow oxygenator provided benefits in terms of gas exchange and platelet conservation, development of a smaller extracapillary blood flow type oxygenator to reduce hemodilution effects would be beneficial.

Experimental study of materials for patch graft on right ventricular outflow tract under extracorporeal circulation in dogs--comparison between Denacol EX-313-treated bovine jugular vein graft and expanded polytetrafluoroethylene (EPTFE) graft

A comparison between a bovine jugular vein treated with a hydrophilic polyepoxy compound cross-linker (Denacol), and expanded polytetrafluoroethylene (EPTFE), an artificial material, as a patch graft for the reconstruction of the right ventricular outflow tract under extracorporeal circulation in dogs, as if they had pulmonic stenosis, was made. Hemodynamic and histological examinations were conducted two weeks after the transplantation. Hemodynamic problems were not observed in either the Denacol or EPTFE groups. Macroscopically, organization of new tissue on the graft surface was more marked in the EPTFE group than in the Denacol group, and newly-formed tissue was seen surrounding the border of the graft and burying it in the EPTFE group. In the Denacol group, microscopic findings revealed the presence of inflammatory cells and fibroblasts, and an invasion of the graft by collagen fibers and elastic fibers. In the EPTFE group, there was minimal cellular infiltration of the graft and a thick layer consisting of collagen fibers and fibroblasts was observed around the graft. These results indicated that two weeks after transplantation the graft was better assimilated and organized with blood vasculature in the patch graft in the Denacol group than in the EPTFE group.

Evaluation of the porcine intestinal collagen layer as a biomaterial

The submucosal layer of the small intestine has been investigated as a source of collagenous tissue with the potential to be used as a biomaterial because of its inherent strength and biocompatibility. In this study we utilized a novel method for processing the tissue to generate an acellular intestinal collagen layer (ICL). This nondetergent, nonenzymatic chemical cleaning protocol removes cells and cellular debris without damaging the native collagen structure. Multilayer laminates of ICL crosslinked with a water-soluble carbodiimide (EDC) were evaluated as a tissue repair material in a rabbit abdominal hernia model. The ICL laminates provided the requisite physical properties and did not lead to adhesion formation. No immune response to the porcine collagen was detectable, and this material did not show any calcification in either the rabbit model or in the juvenile rat model.

A comparative study between hypothermic and normothermic cardiopulmonary bypass in open heart surgery in dogs--effects on systemic hemodynamics

Open heart surgery was performed on two groups of dogs under extracorporeal circulation with or without hypothermia to investigate hemodynamic changes during extracorporeal circulation. During hypothermic cardiopulmonary bypass (CPB), arterial O2 tension and postoperative blood pressure were favorably maintained, indicating that hypothermic extracorporeal circulation can be performed for a long period of time. On the other hand, during normothermic CPB, the average surgical duration was significantly shorter, and marked shifts in the concentrations of various enzymes were suppressed. However, due to reductions in arterial O2 tension, the length of cardiac arrest time was restricted, demonstrating that this method is suitable for performing extracorporeal circulation for CPB of relatively short duration. If circulation circuitry can be improved, such as through the development of a surpassing oxygenator, normothermic CPB would incur less stress on the body, thus making it preferential to hypothermic CPB in most cases.