Learning curve in tracheal allotransplantation.

The first vascularized tracheal allotransplantation was performed in 2008. Immunosuppression was stopped after forearm implantation and grafting of the recipient mucosa to the internal site of the transplant. Nine months after forearm implantation, the allograft was transplanted to the tracheal defect on the radial blood vessels. Since then, four additional patients have undergone tracheal allotransplantation, three (patients 2-4) for long-segment stenosis and one (patient 5) for a low-grade chondrosarcoma. Our goal was to reduce the time between forearm implantation and orthotopic transplantation and to determine a protocol for safe withdrawal of immunosuppressive therapy. Following forearm implantation, all transplants became fully revascularized over 2 months. Withdrawal of immunosuppression began 4 months after graft implantation and was completed within 6 weeks in cases 2-4. Repopulation of the mucosal lining by recipient cells, to compensate for the necrosis of the donor mucosa, was not complete. This resulted in partial loss of the allotransplant in patients 2-4. In patient 5, additional measures promoting recipient cell repopulation were made. The trachea may be used as a composite tissue allotransplant after heterotopic revascularization in the forearm. Measures to maximize recipient cell repopulation may be important in maintaining the viability of the transplant after cessation of immunosuppression.

Pre-operative imaging in primary hyperparathyroidism with ultrasonography and sestamibi scintigraphy.

PROBLEM/OBJECTIVE: Resection of pathological parathyroid glands is the only curative therapy in primary hyperparathyroidism. Adequate pre-operative localization of the pathological glands is very useful, whichever surgical technique is preferred. OBJECTIVES: The aim of our study was to evaluate and compare high resolution ultrasonography and sestamibi scintigraphy as pre-operative imaging techniques and to explore their relationship with certain demographic and biochemical variables. PATIENTS AND METHODS: Data from 368 patients with primary hyperparathyroidism referred for surgery were retrospectively analysed. The results of pre-operative imaging were compared with the operative findings and the anatomopathological report. RESULTS: In predicting the correct side of the lesion (right or left), ultrasonography had a positive predictive value (PPV) of 84%, whereas sestamibi imaging had a PPV of 93%. If both imaging techniques had a concordant positive result, the PPV was 99%. The PPV in predicting the correct quadrant, however, was only 61% for sestamibi scintigraphy and 40% for ultrasonography. CONCLUSIONS: In our study, sestamibi imaging was better than ultrasonography as a single pre-operative localization imaging method for primary hyperparathyroidism. A concordant positive result was exceedingly reliable in indicating the side of the lesion. It seemed far more difficult to predict the quadrant correctly, especially because of misinterpretation of the upper adenomas.

Tumoural perfusion as measured by dynamic computed tomography in head and neck carcinoma.

PURPOSE: To investigate the intra- and interobserver variability, as well as the intra- and interpatient variability of CT-determined tumour perfusion in head and neck tumours, and to evaluate the preliminary value of this parameter as predictive factor of local failure after treatment by definitive radiotherapy. MATERIALS AND METHODS: In 41 patients the perfusion of a primary head and neck squamous cell carcinoma was estimated using dynamic CT. A 40-ml intravenous bolus of a low-osmolar non-ionic contrast agent was rapidly injected over 5 s (8 ml/s), while a dynamic acquisition of image data was obtained during the first pass at the level of the largest axial tumour surface. A time-density curve was constructed for the primary tumour and the carotid artery. The perfusion in the selected tumour region of interest was calculated by dividing the slope of the tumour-time density curve by the maximal value in arterial density. Tumour volume was calculated on the CT-images and correlated with perfusion rate. RESULTS: The mean perfusion rate was 86.4 ml/min per 100 g (median, 80.6; SD, 43.05; range, 31.7-239.8 ml/min per 100 g). No systematic difference was found between the measurements performed by two independent observers. The intratumoural COV was 0.22, the intertumoural COV 0.37. No correlation was found with tumour volume. Ten out of 20 patients with a perfusion rate < 80 ml/min per 100 g were not locally controlled, while nine out of 21 patients with a value > 80 ml/min per 100 g did show a local failure (P = 0.19). CONCLUSIONS: CT-determined perfusion measurements of head and neck tumours are feasible. No correlation with tumour volume and a sufficiently large COV were found to consider this parameter as a possible prognostic factor for outcome after radiotherapy. More patients need to be investigated to test the hypothesis that tumours with a low CT determined perfusion rate have a higher risk of local failure.

Experimental tracheal allograft revascularization and transplantation.

The feasibility of tracheal allotransplantation with a fascial vascular carrier was examined in three groups with varied dose sequences of immunosuppression. A control group (group 1) received no medication. The three experimental groups were given daily cyclosporine intramuscular doses of 5 mg/kg (group 2), 5 mg/kg plus 3 mg/kg methylprednisolone (Solu-Medrol) (group 3), and 10 mg/kg (group 4) for 6 weeks or until death. Grafts were assessed by silicone dye infusion of the artery of the fascial flap to examine their microcirculation and by quantitative histologic study. Group 1 evidenced complete rejection after a heterotopic revascularization period of 14 days. The allografts of the experimental groups remained viable after 14 days of revascularization and could be transplanted orthotopically after this period. After transplantation, the viability of group 2 tracheas was unpredictable with changes ranging from mild to complete rejection. Group 3 evidenced well-preserved transplant viability with infection-induced necrosis at the anastomoses caused by the corticosteroid component. All group 4 animals survived the follow-up period with normal allograft viability. Cyclosporine in a dosage of 10 mg/kg per day can effectively suppress the immune response after transplantation of vascularized tracheal allografts. This experimental model will allow future studies to examine airway wall immunogenicity.

An investigation of airway wound healing using a novel in vivo model.

OBJECTIVE: To study the amount of wound contraction and reepithelialization occurring in the healing process of full-thickness mucosal defects treated with and without mitomycin. STUDY DESIGN: A new wound healing model was developed in which the tracheal mucosa was exteriorized without interference with the blood supply or with the cartilage support of the trachea. This was done by: 1) orthotopic tracheal revascularization in vascularized fascia; 2) isolation of revascularized segment after 14 days; 3) posterior longitudinal incision of revascularized segment; 4) exteriorization of tracheal mucosa with formation of anterior full-thickness mucosal defect; and 5) closure of posterior tracheal incision and reimplantation in the airway. This model was used to study airway wound healing in three groups of animals: 1) controls (revascularization, exteriorization, reimplantation) (N = 6); 2) full-thickness mucosal defect: patch defect (N = 5), circumferential defect (N = 3); and 3) full-thickness mucosal defect after topical mitomycin application: patch defect (N = 7), circumferential defect (N = 3). The animals were followed for periods varying from 2 to 4 weeks or until signs of dyspnea. The surface areas of the wounds before and after follow-up were measured. Wound healing was studied histologically on axial and longitudinal sections. RESULTS: Group 1: All the animals survived for 1 month. No significant difference existed between surface area of isolated trachea and of reimplanted trachea after follow-up. Group 2: Five animals (patch defects) survived for 1 month. Full-thickness mucosal defects healed by reepithelialization and by a surface area reduction of 58.9% (mean - standard deviation = 10.5). The animals with the circumferential defects showed dyspnea after an average follow-up of 14 days as a result of excessive granulation tissue formation. Group 3: Mitomycin reproducibly inhibited wound closure, yielding wounds that on average closed 56% less than controls by day 14 (P <.001). Histologic comparisons showed that mitomycin blocks angiogenesis during wound healing. CONCLUSIONS: A wound healing model based on tracheal revascularization, isolation, and reimplantation was developed in rabbits. This model allowed us to study the healing of full-thickness mucosal defects inside the airway.

Laryngotracheal reconstruction with tracheal patch allografts.

The capacity of tracheal allotransplants in providing optimal tissues for laryngotracheal repair was studied in an animal model. Segments of cervical trachea could be revascularized completely when wrapped in a receptor fascia flap in immunosuppressed rabbits. In phase I the revascularized tracheas were incised longitudinally and transformed into four different patches after a 14-day revascularization period. The blood supply toward the four patch designs was examined with angiography. The patch designs that showed a vascularization over at least 75% of their mucosal surface area were used in phase II to reconstruct extended anterior laryngotracheal defects. The morphologic characteristics of the tracheal patches when used inside laryngotracheal defects were studied using radiographic, angiographic, and histologic techniques. The revascularized allograft patches that were fully supported by tracheal cartilage were most suitable to repair anterior laryngotracheal defects in this animal study. This model allowed us to define the tissue characteristics necessary for obtaining a combination of primary healing and optimal luminal support in the repair of laryngotracheal defects.

Experimental revascularization of airway segments.

A series of experiments was conducted to assess the possibility of revascularizing tracheal autografts with the rabbit lateral thoracic fascial flap. Injection studies and histological evaluation displayed optimal revascularization and reepithelialization of the graft after 2 weeks.

Mucociliary clearance following segmental tracheal reversal.

Ciliated tracheal epithelium is arranged in a polarized pattern oriented according to the inferior-superior axis of the trachea and is responsible for the transport of mucus toward the larynx. In this study, ciliary beat orientation and the influence of external factors on mucociliary clearance direction were studied in rabbit inverted cervical tracheas. The animals displayed normal respiration postoperatively. After 16 weeks, airway clearance was studied by observation of the movement of silicone particles placed in the inverted segment and in normal parts of the ciliated epithelium. Cilia exhibited unidirectional and coordinated movement within inverted tracheal segments. As shown by the direction of effective flow produced by beating cilia and by scanning electron microscopy, the cilia in the inverted segment beat in the opposite direction from the cilia in the remainder of the trachea. This study demonstrated that ciliary orientation is irreversibly determined, but the reversal of ciliary beating within the cervical trachea had no adverse effects on the survival of the animals.

Tracheal autotransplantation: a reliable reconstructive technique for extended hemilaryngectomy defects.

OBJECTIVES: Current surgical treatment for a glottic cancer with significant subglottic extension is a total laryngectomy. The objective of this study was to expand laryngeal conservation procedures by using a reconstructive technique that allows for the repair of hemicricolaryngectomy defects. STUDY DESIGN: After resection of the ipsilateral thyroid, cricoid, and arytenoid for advanced T3 glottic cancer, the laryngeal defect was reconstructed by means of an autotransplanted segment of trachea in four patients. The reconstruction consisted of a transferable patch that was constructed from a segment of revascularized cervical trachea. METHODS: During a 14-day period, a 4-cm segment of cervical trachea was wrapped by a free radial forearm fascial flap. In the second stage, the glottic cancer was removed and the cervical trachea was isolated on its fascial blood supply and transformed into a patch that was used to repair the extended hemilaryngectomy defect. Two different patch designs were used. Two patients underwent reconstruction with a patch augmented at the glottic level (group A); two patients underwent reconstruction without glottic augmentation on the patch (group B). Tracheal continuity was restored by an end-to-end reanastomosis. The postreconstruction morphology of the two patch designs was compared with the preoperative laryngeal morphology. RESULTS: The autotransplantation technique led to complete restoration of the subglottic airway lumen in all four patients. Although the anterior-posterior glottic diameter was reduced by 36% in group A patients and by 43.5% in group B patients, a sufficient glottic airway lumen was obtained. The glottic sphincteric function was restored in both groups. CONCLUSIONS: Tracheal autotransplantation may be used reliably to repair hemicricolaryngectomy defects. Augmentation of the patch at the level of the glottis is not essential for successful rehabilitation.

Tracheal autograft revascularization and transplantation.

OBJECTIVE: No vascular pedicle can be obtained reasonably to provide revascularization of a tracheal graft by direct microvascular suture. This study is a morphometric analysis of epithelial regeneration, submucosal revascularization, and mucosal thickness of isolated, tracheal segments revascularized by a lateral thoracic fascial flap. The purpose of the first part of the study is to determine the optimal period of tracheal viability after isolation and revascularization. The second part consisted of a reimplantation of the revascularized autograft into its original tracheal location. DESIGN: A tracheal segment was excised in 30 animals, and the segment was wrapped in the lateral thoracic fascia. The segments were reviewed histologically and morphometrically 2 to 28 days after graft isolation and after injection of the lateral thoracic artery with a blue silicone dye. Twelve grafts were reimplanted. Six segments were reinserted in the original direction and six segments were reinserted in the opposite direction. Tracheal airway clearance was studied by observation of the movement of carbon particles placed at different locations on the native and transplanted tracheal mucosa. MEAN OUTCOME MEASURES: Tracheal autograft revascularization and reepithelialization. RESULTS: Histologic evaluation of the revascularized grafts revealed an optimal viability of the autograft 16 to 20 days after isolation. The autografts could be reimplanted successfully after this period. This demonstrated the viability of the isolated grafts after a revascularization period of 16 days. The original direction of the mucosal clearance was preserved after reimplantation. The clearance in the opposite direction, with the 180 degrees rotated segments, however, had no influence on survival.

The role of immunosuppression in the long-term survival of tracheal allografts.

OBJECTIVES: To assess the functional aspects of vascularized tracheal allograft transplant models and the long-term fate of these allografts. To examine the effects of cyclosporin A (CsA), 10 mg/kg per day, on the long-term survival of vascularized tracheal allografts and the presence and significance of host immune tolerance after cessation of immunosuppression. DESIGN: In a rabbit model, tracheal allografts were orthotopically transplanted after an initial period of heterotopic fascia revascularization. A full-thickness skin allograft from the same donor was used as an external monitor of the rejection process. Treatment with CsA was discontinued (group 2) or given intermittently (group 3) after an initial course of continuous CsA administration varying from 2 to 10 weeks. The first group received a continuous regimen of CsA for 10 weeks. MAIN OUTCOME MEASURES: Tracheal and skin allograft deterioration, microcirculation of tracheal transplant, mucociliary clearance, and histopathologic examination. RESULTS: Tracheal allografts under continuous immunosuppression with CsA, 10 mg/kg per day, showed no rejection and remained functional with preservation of mucociliary activity. After an initial course of CsA to achieve solid tracheal union, subsequent cessation and intermittent pulsing of the immunosuppressant were insufficient in maintaining indefinite graft survival. Chronic allograft rejection with simultaneous endothelial graft repopulation could be induced by intermittent pulsing of CsA, which led to prolonged allograft survival in some group 3 animals. CONCLUSION: Continuous immunosuppression is necessary to preserve an optimal morphological and functional condition of tracheal allografts.

Hypopharyngeal stenosis and fistulas. Use of the radial forearm flap.

The radial forearm flap is a thin, pliable, and well-vascularized fasciocutaneous flap. The forearm flap is, in selected cases, along with the pediculated regional and distant musculocutaneous flaps, a versatile method for pharyngeal reconstruction. We describe the use of the flap in nine clinical cases of hypopharyngeal stenosis and fistulas. The advantages of this method for hypopharyngeal reconstruction are presented.

Results of larynx preservation surgery for advanced laryngeal cancer through tracheal autotransplantation.

OBJECTIVE: To evaluate the use of tracheal autotransplantation for reconstruction of the hemilaryngectomy defect that includes the hemicricoid cartilage and results from resection of laryngeal or hypopharyngeal cancer. DESIGN: The clinical records of 28 patients undergoing primary or salvage hemicrico-hemilaryngectomy for laryngeal (26 patients) and pyriform sinus (2 patients) cancer were analyzed for function and local control. SETTING: Academic center. PATIENTS: Case series review of 28 consecutive patients treated during a 3(1/2)-year period who had an average follow-up period of 19 months. INTERVENTION: Twenty-five men and 3 women, aged from 28 to 79 years, underwent a hemilaryngectomy that included the hemicricoid cartilage, the ipsilateral thyroid lobe, and a unilateral or bilateral lymph node dissection. In 26 patients, these extensive defects were reconstructed with a tracheal autotransplantation that restored the larynx at the glottic and subglottic levels. In 2 patients, the defect was converted into a total laryngectomy because of tumor extension beyond the resection margins of a hemicrico-hemilaryngectomy. MAIN OUTCOME MEASURES: The times to decannulation and retake of full oral feeding, the quality of speech, and the incidence and site of recurrent cancer were assessed. RESULTS: Of the 26 patients undergoing tracheal autotransplantation, 24 were decannulated and all regained the ability to maintain nutrition by mouth. Ultimate voice quality was "subnormal" to "moderately hoarse" in all patients. Five recurrences developed of which 2 were treated with total laryngectomy. CONCLUSIONS: Functional reconstruction of extensive laryngeal defects can be achieved with an autotransplantation of cervical trachea, with favorable functional results and acceptable morbidity. This technique expands the limits of conservation surgery for selected laryngeal and hypopharyngeal tumors.

Magnetic resonance imaging of experimental tracheal transplantation.

RATIONALE AND OBJECTIVES: We evaluated the feasibility of using contrast-enhanced magnetic resonance (MR) imaging for in vivo monitoring of tracheal transplants in rabbits. METHODS: Plain and gadolinium-enhanced, high-resolution MR images were obtained from six rabbits 4 weeks to 6 months after an orthotopic tracheal transplantation (after heterotopic revascularization). The animals were sacrificed after the MR examination, and comparisons were made among the MR images, macroscopic observations, and histologic sections. RESULTS: All transplants were clearly identifiable on the MR images; they produced slight-to-moderate narrowing of the airway diameter. Enhancement of the transplant tissues was clearly present. There was close correspondence between the MR morphology and the macroscopic and histologic sections. CONCLUSION: MR imaging can be used to monitor in vivo tracheal transplantation after heterotopic revascularization.

Tracheal side effects of endoscopic balloon tracheal occlusion in the fetal lamb model.

OBJECTIVE: To evaluate effects of in-utero endoluminal balloon tracheal occlusion (TO) as suggested for the treatment of Congenital Diaphragmatic Hernia (CDH) on the higher airways of a fetal lamb model. STUDY DESIGN: Fetuses from time-dated pregnant ewes underwent at 94 days (term=145 days) in-utero tracheal occlusion. In study animals an endoluminal, detachable balloon was placed by tracheoscopy. For that purpose a 1.2mm fibre-optic, semi-rigid endoscope and a medically graded latex balloon were used. In group I (n=9) lambs were delivered after 2 weeks. In group II (n=8) the tracheal occlusion was released after 2 weeks, to allow in-utero recovery until term. In positive control animals (group III; n=5) the trachea was clipped at 98 days and fetuses were harvested near term by cesarean section. A total of 17 contralateral littermates in multiple pregnancies served as negative controls. After macroscopic inspection of the trachea, sections were evaluated by light microscopy. Alterations were scored with an empirical interval score for each of the different anatomical elements in the fetal trachea (epithelium, submucosa, cartilage, pars membranacea). RESULTS: For the animal experiments in group I, all balloons were found in place and according to the pulmonary response they were obstructive. Tracheas were macroscopically dilated by the plug mainly due to elongation of the pars membranacea. The total histologic score was correlated to the increase in circumference (mean increase: 3.0mm). In nearly all cases, the tracheal epithelium at the level of the plug had lost its typical folding pattern. In 44% of cases, local epithelial defects were observed and in 33% of cases there was squamous metaplasia. A chronic inflammatory response was present in over half of the cases, sometimes with giant cell reaction. In group II (the in-utero recovery group) the total score was significantly lower than in group I, with much less prominent unfolding and absence of epithelial defects. Squamous metaplastia was still present in half of the cases; whereas inflammatory responses were less frequent. In group III the trachea expanded normally after removal of the clip. The epithelium had compacted folds, and cilia were well preserved. In two animals however, intraluminal synechia were observed. Below the level of occlusion animals of groups I and II all showed areas of unfolding, but without metaplasia or epithelial defects. CONCLUSION: Tracheal obstruction by means of endoluminal plugging has been suggested as an alternative in-utero treatment for congenital diagphragmatic hernia. The balloon causes mild epithelial changes, such as unfolding, limited epithelial defects (<25% of the exposure surface) and local inflammatory changes. These changes disappear nearly completely following in-utero unplugging during the rest of gestation. Unfolding of the epithelium is also seen in the trachea under the plug.

Experimental tracheal tube created with vascularized fascia.

An experimental fascial transferable bed was developed in the rabbit model. This tissue is reliable in bringing a viable mucosal graft inside the larynx. A vascular connective tissue sheet with full-thickness mucosa and autogenous cartilage for external support are needed. In this study a tracheal tube was preformed to study the use of autogenous cartilage as support for a circumferential lumen.

Vascularized fascia as a transferable bed for experimental laryngeal reconstruction.

Laryngeal defects were reconstructed with a combined vascular flap consisting of lateral thoracic fascia used as a transferable vascular bed. A buccal mucosal graft was fixed on this bed as an internal lining. An autogenous cartilage graft, circumferentially wrapped in vascular connective tissue, was used as external support. The first focus of interest of this experimental study was to investigate the necessity of epithelial lining in the repair of a full-thickness laryngeal wall defect. The second focus of interest was to study reconstruction of the posterior glottis by introducing additional supporting material.

Autotransplantation of the trachea: experimental evaluation of a reconstructive technique for extended hemilaryngectomy defects.

Vascularized segments of trachea were used to repair extended hemilaryngectomy defects in a rabbit model. The cervical trachea was revascularized in a first stage by a fascia flap. In a second stage, the cervical trachea was isolated and transformed into a patch that could be autotransplanted on a vascular carrier. The patches were used for the reconstruction of hemilaryngectomy defects including half of the cricoid. Two months after transplantation, the vascular and morphologic characteristics of the tracheal patches were examined with silicone dye angiography and magnetic resonance imaging. The tracheal patches showed a reliable blood supply when wrapped in vascularized fascia. The patches provided a functional reconstruction of hemicricolaryngectomy defects. It is concluded that autotransplantation of the trachea should be further explored as a potential means for extending the limits of conservation laryngeal surgery.

Epiglottoplasty for reconstruction of posttraumatic laryngeal stenosis.

Laryngeal stenosis secondary to blunt laryngeal trauma is mostly localized at the supraglottic and glottic levels. The epiglottis is ideally suited to reconstruct the defect after excision of supraglottic and glottic scar tissue and anterior thyroid cartilage. It is the conclusion of the authors that epiglottic reconstruction is an effective procedure for repair of laryngeal stenosis at the supracricoid level. Two case reports are given.

Prefabrication of composite tissue for improved tracheal reconstruction.

Tracheal repair tissues were evaluated experimentally to provide an evidence-based choice for decision-making in clinical tracheal reconstruction. Tracheal reconstructive tissue was characterized as providing for vascularization, support, and/or lining. A tissue equivalent was developed in the rabbit for each of the individual tissues. The individual tissues consisted of nonepithelialized soft tissue (vascularized fascia), epithelialized tissue (vascularized fascia grafted with buccal mucosa), and supportive tissue (ear cartilage). The 3 reconstructive tissues were evaluated in 30 rabbits after repair of an anterior laryngotracheal defect. Morphometric and histologic analysis was applied to the reconstructions. After a 1-month follow-up period, defects repaired with nonepithelialized soft tissue showed healing by secondary intention and a wound that was contracted to 44% of the initial surface area of the defect. Mucosa-lined soft tissue flaps and cartilage grafts showed a less than 10% wound contraction. Compared to cartilage grafts, mucosalined soft tissue (vascularized fascia grafted with buccal mucosa) seemed preferable for clinical use, because it showed healing by primary intention. A mucosa-lined radial forearm fascia flap was used successfully in cases of restenosis after tracheal resection. One deficiency of the mucosa-lined soft tissue was the absence of supportive tissue. In cases of extensive stenosis, it might be useful to obtain additional expansion of the airway lumen by creating a convexity at the site of reconstruction. In a second set of experiments, we attempted to improve the mucosa-lined soft tissue concept by adding elastic cartilage. A composite tissue consisting of vascularized fascia, buccal mucosa, and auricular cartilage was developed. Heterotopic prefabrication of the composite tissue was essential for survival of the cartilaginous component. Additional airway lumen expansion could be obtained after heterotopic flap prefabrication. After experimental evaluation, the concept of the prefabricated composite tissue was successfully applied in a clinical case of long-segment stenosis. Experimental and clinical evidence suggests that the combination of buccal mucosa and fascia form an optimized tissue combination for tracheal reconstruction. This combination can be improved by adding strips of autologous ear cartilage.