Minoru Aoki

Surgical treatment for invasive thymoma, especially when the superior vena cava is invaded

BACKGROUND We analyzed the operative outcome of extensive surgery for invasive thymoma, especially in those with thymomas invading the superior vena cava, the left innominate vein, or both. METHODS We treated 41 patients with invasive thymoma, including 34 stage III, 5 stage IVa, and 2 stage IVb thymomas. Thirty-eight patients received radiotherapy preoperatively or postoperatively. In 12 patients with invasion of the superior vena cava or innominate vein, we performed angioplasty, reconstruction, or both. RESULTS The overall 5-year survival rate was 77% and the 10-year survival rate was 59%. In the stage III group, there was a significant difference between those with complete and those with incomplete resection. Ten of 12 patients who had angioplasty with or without reconstruction of the superior vena cava or innominate vein survived without recurrence of the tumors. CONCLUSION Angioplasty and vascular reconstruction are recommended because successful treatment for invasive thymomas depends on complete resection of the tumors.

Omentoplasty for postpneumonectomy bronchopleural fistulas

Postpneumonectomy fistula is one of the most serious complications in general thoracic surgery and remains difficult to manage. From 1984 to 1991, we successfully used pedicled omentum for the treatment of postpneumonectomy bronchopleural fistulas (omentoplasty) in five patients, four of whom had thoracic empyema. For bronchopleural fistulas without early postoperative infection, single-stage closure was performed which was then covered with pedicled omentum. Omentoplasty was performed successfully in patients with thoracic empyema, after open or closed drainage. Open thoracotomy was useful when closed drainage was ineffective. Even after open thoracotomy, closure of the wound was achieved. All five patients could be discharged. Omentoplasty was useful in the therapy of postpneumonectomy bronchopleural fistula even in the presence of thoracic empyema.

Intracapsular enucleation of vagus nerve-originated tumors for preservation of neural function.

Tumors arising from the cervical vagus nerve are relatively rare. Most of them are neurilemmomas, neurofibromas, and paragangliomas. In the management of neurilemmomas, because they are benign and encapsulated, intracapsular enucleation is often performed in an effort to preserve function of the nerve.1 In previous reports, however, postoperative nerve palsy frequently occurred, and in some cases the nerve function did not recover. On the other hand, there have been few attempts to preserve nerve function in the resection of neurofibromas.1 In this report, we performed intracapsular enucleation for 2 vagal tumors: neurilemmoma and neurofibroma. In both cases tumors were completely excised with nerve fibers preserved. In the first case, postoperative palsy did not occur. In the second case transient incomplete vocal cord palsy was observed, but the cord recovered in 6 months. During the ablation of tumors, we monitored nerve function using a nerve stimulator and avoided damaging nerve fibers as much as possible. This procedure may have helped us to preserve nerve function in the resection of not only a neurilemmoma but also a neurofibroma.

An evaluation of the tolerance of the autotransplanted canine lung against warm ischemia

Left lung autotransplantation was performed in mongrel dogs to examine the limitation of tolerance of the deflated lung against warm ischemia in a warm ischemic time (WIT) range of 60–360 minutes. The animals were divided into the 4 following groups according to the duration of WIT and the use of heparin: Group 1; WIT 60–120 min., heparin (−), Group 2; WIT 120–240 min., heparin (+), Group 3; WIT 240–360 min., heparin (+), and Group 4; WIT 240–360 min., heparin (−). All the Group 1 animals tolerated a right pulmonary artery ligation on the 6th postoperative day, but some of the Group 2 animals died immediately after the reimplantation due to pulmonary edema. All the Groups 3 and 4 animals died. The PaO2 values during the right pulmonary artery occlusion, immediately after the reimplantation, correlated well with the survival of the animals. The maximum tolerable WIT of the deflated dog lung was considered to be 120 minutes.

Application of laser Doppler velocimetry to lung transplantation.

The relationship between healing of a bronchial anastomosis and regional blood flow was studied in adult mongrel dogs after allotransplantation of the left lung. Animals were divided into the following three groups according to the immunosuppressive regimen. Group A: no immunosuppressive treatment (n = 7); Group B: azathioprine (5 mg/kg/day) and prednisolone (2 mg/kg/day) (n = 4); Group C: cyclosporine (20 mg/kg/day) (n = 4). The mucosal blood flow was examined serially after transplantation with laser Doppler velocimetry (LDV) at the tracheal bifurcation of the recipient (1st LDV) and at the bifurcation of the upper lobe bronchus of the transplanted lung (2nd LDV). The LDV values were expressed as a ratio to the preoperative values at the same site. Healing of the bronchial anastomosis was also assessed macroscopically with a fiberoptic bronchoscope and microscopically. The 2nd LDV value of the animals in group A at 13 days after transplantation remained low (32.9 +/- 27.6%). The 2nd LDV value in group B, although not significantly different from group A, had recovered to the preoperative level by that time (93.7 +/- 23.4%). By contrast, the 2nd LDV value in group C remained significantly higher than that in group A (119.9 +/- 23.0%, P less than 0.05). The 1st and 2nd LDV values were reduced in animals having infection at the bronchial anastomosis, even those in groups B and C. Bronchial mucosal blood flow appeared to be affected by infection and rejection of the transplanted lung, and to correlate closely with the healing of the bronchial anastomosis. This LDV method is useful to evaluate bronchial mucosal blood flow in experimental, and possibly in clinical, fields.

Effect of methylprednisolone and prostacyclin on bronchial perfusion in lung transplantation

In an experimental investigation using modified unilateral lung transplantation in pigs, the effects of systemic administration of methylprednisolone and prostacyclin on bronchial mucosal blood flow were assessed. Laser Doppler velocimetry (LDV) and radioisotope studies using radiolabeled erythrocytes (RI) were employed to measure blood flow at the donor main carina and upper lobe carina after 3 hours of reperfusion. The recipient carina was used as a reference point. Five groups of 6 animals each were studied. Group I served as control. In group II, methylprednisolone (20 mg/kg) was administered to the recipient. In group III, prostacyclin (4 ng.kg-1.min-1) was given to the recipient, and in group IV, prostacyclin (100 micrograms intravenously) was administered to the donor. In group V, prostacyclin was given to the recipient and the donor animals as in groups III and IV, respectively. In group I, bronchial blood flow at the donor main carina was 37.6% +/- 2.2% (LDV) and 44.1% +/- 14.8% (RI) of reference blood flow. No significant differences were found between the controls and groups II, III, and IV. In group V, bronchial blood flow was markedly increased both at the donor main carina (LDV, 39.8% +/- 6.2%, p = 0.12; RI, 55.7% +/- 11.4%, p < 0.2) and the donor upper lobe carina (LDV, 65.8% +/- 5.4%, p < 0.05; RI, 76.8% +/- 21.3%, p < 0.2). We conclude that systemic administration of prostacyclin to the donor and recipient results in marked improvement of bronchial blood flow and may reduce the incidence of bronchial complications after lung transplantation.

Spontaneous rupture of mediastinal cystic teratoma into the pleural cavity : Report of two cases and review of the literature

The authors report on two female patients aged 12 and 14 years, who spontaneously developed a rupture of benign mediastinal cystic teratoma into the right pleural cavity. They presented with acute onset of severe chest pain and respiratory distress. The tumors were completely resected by thoracotomy. The serum and pleural fluid levels of carcinoembryonic antigens, CA-125 and CA19-9 were invariably elevated, then decreased to normal range after the surgical resection. Rapid diagnosis of this extremely rare complication is important because it may progress to a life-threatening condition.

International Articles: International Case ReportsIntracapsular enucleation of vagus nerve-originated tumors for preservation of neural function

Tumors arising from the cervical vagus nerve are relatively rare. Most of them are neurilemmomas, neurofibromas, and paragangliomas. In the management of neurilemmomas, because they are benign and encapsulated, intracapsular enucleation is often performed in an effort to preserve function of the nerve.1 In previous reports, however, postoperative nerve palsy frequently occurred, and in some cases the nerve function did not recover. On the other hand, there have been few attempts to preserve nerve function in the resection of neurofibromas.1 In this report, we performed intracapsular enucleation for 2 vagal tumors: neurilemmoma and neurofibroma. In both cases tumors were completely excised with nerve fibers preserved. In the first case, postoperative palsy did not occur. In the second case transient incomplete vocal cord palsy was observed, but the cord recovered in 6 months. During the ablation of tumors, we monitored nerve function using a nerve stimulator and avoided damaging nerve fibers as much as possible. This procedure may have helped us to preserve nerve function in the resection of not only a neurilemmoma but also a neurofibroma.

Bronchial circulation after experimental lung transplantation: the effect of direct revascularization of a bronchial artery

Direct revascularization of a bronchial artery has been proposed as a measure to alleviate the problem of bronchial ischemia after lung transplantation. To assess the effect of restoration of arterial blood flow to the transplanted bronchus, bronchial mucosal blood flow was measured in a model of modified unilateral lung transplantation in pigs. Laser Doppler velocimetry (LDV) and radioisotope studies using radio-labeled erythrocytes (RI) were used to measure blood flow at the donor main carina (DC) and upper lobe carina (DUC) after 3 h of reperfusion. The recipient carina was used as a reference point; values obtained by LDV and RI were expressed as percentage of blood flow at the recipient carina. Two groups of animals were studied. In group 1 (n = 6) standard unilateral transplantation was performed; in group 2 (n = 6) a left bronchial artery was reimplanted into the descending thoracic aorta of the recipient. No differences were observed between the two groups with respect to preoperative or postoperative gas exchange or hemodynamics. In group 1, bronchial blood flow at the DC was 37.6 +/- 2.2% (LDV) and 44.1 +/- 14.8% (RI) of reference blood flow. At the DUC, blood flow was 54.9 +/- 7.7% (LDV) and 61.6 +/- 25.7% (RI) of normal flow. In group 2, blood flow was increased at the DC as measured by LDV (55.3 +/- 17.1%; p less than 0.05) and by RI (60.8 +/- 25.3%; p less than 0.2). A similar increase was found at the DUC (LDV: 81.8 +/- 19.3%; p less than 0.05; RI: 88.6 +/- 31.0%; p less than 0.2). It is concluded that there is a significant gradient of blood flow from intra- to extrapulmonary airways after lung transplantation. Reimplantation of a bronchial artery results in significant improvement of graft bronchial blood flow. Restoration of bronchial perfusion to normal levels, however, cannot be achieved, suggesting a possible defect in the microcirculation of the donor airways.

Atypical carcinoid of thymus associated with multiple endocrine neoplasia syndrome type 1

Thymic carcinoid associated with multiple endocrine neoplasia syndrome type 1 (MEN-1) is a rare tumor. We report a case of MEN-1-related thymic carcinoid. The patient reported herein had already been diagnosed with MEN-1 and was found to have a mediastinal mass. She underwent thymectomy with partial resection of the left innominate vein and lung. Histological examination revealed atypical carcinoid with infiltration. MEN-1 gene mutation was detected by employing the direct nucleotide sequencing method. Postoperative 2-fluoro-2-deoxyglucose positron emission tomography showed probable multiple metastases in the vertebrae and myocardium. However, she has been alive and asymptomatic for 2 years postoperatively. MEN-1-related thymic carcinoid is often insidious with a poor prognosis. We suggest chest computed tomography scan or magnetic resonance imaging for MEN-1 patients and serological or genetic screening for patients with thymic carcinoid to screen for MEN-1.