Yoichi Muto

Effect of wall shear stress on intimal thickening of arterially transplanted autogenous veins in dogs

To determine whether or not changes in wall shear stress play a determinant role in the induction of hyperplasia of intimal tissue of arterially transplanted vein grafts, we developed two models of canine femoral arteries. Wall shear stress was defined by variation of wall shear stress (tau-variation) in the cardiac cycle, with the use of a newly designed computational flow waveform analyzer. In the group I model autogenous vein grafts were implanted under flow conditions of 79.7 +/- 3.2 ml/min of the normally high flow rate with 33.1 +/- 1.9 dynes/cm2 of low tau-variation. In the group II model grafts were implanted under conditions of 2.9 +/- 1.8 ml/min of low flow rate with 178.8 +/- 11.0 dynes/cm2 of normally high value of tau-variation. The intimal thickness of 259 +/- 36 microns 4 weeks after implantation in group I was statistically significant compared with that of 31 +/- 14 microns in group II (p less than 0.005). Our study revealed that change in wall shear stress and not the rate of blood flow is the essential hemodynamic factor related to intimal hyperplasia.

Abdominal surgery for patients on maintenance hemodialysis

Despite the growing number of major surgical procedures being performed for patients on maintenance hemodialysis, few reports focus on the management and outcome of such patients, especially those undergoing major abdominal surgery. We conducted a retrospective review of 30 patients on maintenance hemodialysis who underwent abdominal surgery, 20 of whom underwent an elective operation and 10, an emergency operation. The indications of elective surgery included gastrointestinal cancer, biliary tract disease, and abdominal aortic aneurysm, while those for emergency surgery mainly involved gastrointestinal perforation or bleeding. There were no statistically significant differences between the elective group and the emergency group regarding either the mean time on hemodialysis or the preoperative clinical data. The morbidity and mortality rates were 15% and 10%, respectively, for the patients who underwent elective surgery and 50% and 70%, respectively, for those who underwent emergency surgery (P<0.01 andP<0.05, respectively). Those patients with more than a 2-year history of hemodialysis had a significantly higher mortality rate following abdominal surgery than those with less than a 2-year history (P<0.01). Thus, the morbidity and mortality rates of patients on maintenance hemodialysis who require major abdominal surgery are significantly high, which reinforces the need to further improve the intensive perioperative management of such patients.

A COMPARISON OF OPEN AND LAPAROSCOPIC CHOLECYSTECTOMY FOR PATIENTS WITH CIRRHOSIS

To evaluate the benefits of performing laparoscopic cholecystectomy (LC) in patients with cirrhosis, data on 13 patients with liver cirrhosis who underwent cholecystectomy for gallstones between 1989 and 1995 were retrospectively collected from charts filed at Fukuoka City Hospital. These 13 patients were classified into two groups; one, comprised of 7 who underwent LC, and anothe, comprised of 6 who underwent open cholecystectomy (OC). No statistical differences were observed in the duration of surgery or the intraoperative blood loss between the two groups; however, the C-reactive protein (CRP) level in the serum was significantly higher in the OC group than in the LC group. LC was followed by a significantly earlier resumption of a normal diet (P<0.05) and a shorter hospital stay (P<0.05) in comparison to OC. All of the patients who underwent OC had an uneventful clinical course; however, one of the patients who underwent LC suffered from intractable ascites postoperatively. The difference in the cost of hospitalization between the two groups was not statistically significant. These findings suggest that the therapeutic significance of performing LC in patients with cirrhosis should be assessdd after carefully evaluating all factors including mortality, morbidity, and cost-effectiveness. Thus, further controlled trials are necessary.

Rupture of embolised coeliac artery pseudoaneurysm into the stomach: is coil embolisation an effective treatment for coeliac anastomotic pseudoaneurysm?

An elderly woman with an anastomotic pseudoaneurysm of the coeliac artery, after previous treatment of a thoraco-abdominal aortic aneurysm, was treated by stainless steel coil embolisation. One year later, the embolised pseudoaneurysm ruptured into the stomach and total gastrectomy and aneurysmorraphy was necessary. She is leading a normal life 6 months later.

Flow waveform assessment of polytetrafluoroethylene grafts for reconstruction of lower extremity arteries: A preliminary report

On the basis of our findings that the outcome of reconstructive surgery for lower limbs could well be predicted by flow waveform analysis, we reviewed femoropopliteal arterial bypass operations involving the use of polytetrafluoroethylene (PTFE) grafts for 35 patients. Of 38 grafts, 26 were PTFE alone, and 12 were PTFE/vein composite grafts. Neither ankle pressure index nor angiographic distal runoff was of predictive value as a prognostic indicator. The cumulative patency rate, calculated by the life-table method, revealed the usefulness of flow waveform analysis for prediction of the outcome of PTFE grafts. In type 0 or I flow, the patency rate was 94% at 1 and 2 years and 79% at 3 years. In contrast, in type II flow, the patency rate was 74% at 1 year, 66% at 2 years, and 49% at 3 years, with a statistical significance at 2 and 3 years (p less than 0.05). Comparison of the result of PTFE grafts with that of PTFE/vein composite grafts showed superior results of composite grafts at 3 years after implantation (42% vs. 83%, p less than 0.05). These findings indicate that flow waveform analysis is useful for prediction of the outcome of PTFE grafts and that PTFE/vein composite grafts should probably be used, particularly in cases of abnormal blood flow.

The Simultaneous Expression of Peroxisome Proliferator-Activated Receptor Delta and Cyclooxygenase-2 May Enhance Angiogenesis and Tumor Venous Invasion in Tissues of Colorectal Cancers

We conducted this study to evaluate the impact of the expression of peroxisome proliferator-activated receptor delta on angiogenesis in tissue samples of colorectal cancer. We examined 52 samples of primary human colorectal carcinomas and matched normal adjacent tissues to evaluate the expression of peroxisome proliferator-activated receptor delta, cyclooxygenase-2, vascular endothelial growth factor-A, and CD34 through immunohistochemical analysis. Peroxisome proliferator-activated receptor delta was expressed in 25 (48.1%), and cyclooxygenase-2 was expressed in 26 (50.0%) of total colorectal cancer tissues. Tissue samples were divided into four groups, according to the expression of peroxisome proliferator-activated receptor delta and cyclooxygenase-2. The positive rate of vascular endothelial growth factor-A, the levels of microvascular density, and the incidence of venous vessel invasion in peroxisome proliferator-activated receptor delta (+)/cyclooxygenase-2 (+) samples exceeded significantly those in the other three groups of tissue samples (P < 0.05). The results suggest that the axis of the cyclooxygenase-2/peroxisome proliferator-activated receptor delta signal pathway might play a crucial role in the development of colorectal cancers by enhancing angiogenesis.

Primary Neuroendocrine Carcinoma Coexisting with Hemangioma in the Liver : Report of a Case

Primary hepatic neuroendocrine carcinoma is an extremely rare liver tumor. We herein report a case of primary hepatic neuroendocrine carcinoma coexisting with a hemangioma in a 66-year-old man. Ultrasonography, computed tomography, and magnetic resonance imaging showed a tumor (1.5 cm in diameter) coexisting with a hemangioma in the lateral segment of the liver. Liver biopsy showed malignant cells, and several examinations revealed no alternative primary source. We performed a lateral segmentectomy. Microscopically, the tumor cells had round to oval nuclei and eosinophilic cytoplasm, proliferated in thick trabeculae or solid nests, and formed a focal rosette pattern. Mitotic cells were frequently observed. Immunohistochemically, the tumor cells were positive for the endocrine markers chromogranin A, neuron-specific enolase, and neural cell adhesion molecule, but negative for α-fetoprotein and hepatocyte-specific antigen. The patient is still alive after 3 months, without recurrence.

Doppler flow waveform analysis aids in early detection of late graft failure in cases of lower extremity arterial reconstruction: case studies

From 1977 through 1986, 221 patients undergoing arterial reconstructions of the lower extremities, including 78 aortofemoral, 121 femoral-distal, and 22 extraanatomic reconstructions, were followed up after discharge, by use of Doppler driven flow waveform analysis and the ankle pressure index. In 40 (18%) of 221 patients, deterioration in the flow waveform pattern was detected, 5 aortofemoral (6.4%), 31 femoral-distal (25.6%), and 4 extraanatomic (18.2%) reconstructions, respectively. In 37 patients, changes in the flow waveform pat tern were detected within two and a half years after the initial surgery, and in those with a type II flow waveform pattern at the time of discharge, there was a greater tendency toward deterioration of flow waveform pattern. In 32 patients, the ankle pressure index decreased in parallel with deterioration in the flow waveform pattern. The remaining 8 patients (20%) showed no decrease in the ankle pressure index, despite a deterioration in the flow waveform pattern. In the 26 patients who consented, immediate arteriography identified the cause of the hemodynamic failure as localized graft stenosis, including the anastomotic site in 10 patients, inadequate outflow in 7, poor inflow in 6, combined graft stenosis and poor outflow in 2, and combined poor inflow and outflow in 1. Reoperation was performed in 23 patients and was successful in correcting the hemodynamic failure. The results of this study suggest that Doppler driven flow waveform analysis is preferable to ankle pressure index assessment for detect ing early stenotic lesions of the reconstructed artery and that patients with the type II flow waveform pattern should be closely followed up.

Duodenal Gastrointestinal Stromal Tumor Treated by Wedge Resection in a Patient with Neurofibromatosis Type 1: Report of a Case and Review of the Japanese Literature.

A case of duodenal gastrointestinal stromal tumor (GIST) treated by wedge resection in a patient with neurofibromatosis type 1 (NF-1) is reported. A 55-year-old man with a history of NF-1 was admitted for surgery for a duodenal tumor. Upper gastrointestinal endoscopy revealed a 2.5 cm duodenal submucosal tumor. Abdominal computed tomography showed a homogenously enhanced mass in the third portion of the duodenum. The patient successfully underwent wedge resection of the duodenal tumor. Histological examination revealed proliferation of spindle tumor cells arranged in a bundle pattern. This tumor was immunohistochemically positive for c-Kit and CD34, and negative for S-100 and α-SMA. A mitotic count showed 3 mitoses per 50 high-power fields. The tumor was diagnosed as a low-risk GIST. The patient’s postoperative course was uneventful. GIST in a patient with NF-1 is rare, only 27 cases being reported in the Japanese literature.

Cecal volvulus in cerebral palsy: report of a case.

A rare case of cecal volvulus in cerebral palsy that was preoperatively diagnosed and surgically treated without complications is herein reported. A 45-year old man, who had been treated for cerebral palsy as a result of a neonatal cerebral hemorrhage, was admitted to our hospital because of abdominal pain and vomiting. A plain abdominal X-ray film showed evidence of a huge quantity of gas in the left abdomen. Using a gastrographin enema from the colonoscope, an obstruction of the ascending colon was revealed with tapering of the lumen. A computed tomography scan showed a grossly dilated air-distended bowel in the left abdomen and soft tissue with internal architecture containing swirling strands of soft tissue and fat attenuation. An emergency laparotomy was performed. During the laparotomy the ileocecal region, which was unfixed at the retroperitoneum, was found to be twisted counterclockwise by 360° around the mesentery with the terminal ileum, thus resulting in a diagnosis of cecal volvulus. We therefore conducted an ileocecal resection. Cecal volvulus is an uncommon form of intestinal obstruction with a high mortality rate and may present considerable difficulty in diagnosis. Although cecal volvulus is rare as a cause of intestinal obstruction, it should be included in the differential diagnosis of bowel obstruction in cerebral palsy.