Takashi Yukizane

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.

Esophageal stricture in Crohn's disease: A case report

We treated a 46-year-old Japanese man with Crohns disease of the esophagus and for whom medical therapy was adequate. Crohns disease of the esophagus is a rare disease without specific clinical features and establishment of the diagnosis with guided biopsy is extremely difficult. Therefore, Crohns disease of the esophagus should be considered in the differential diagnosis of biopsy-negative carcinoma of the esophagus in order to avoid major surgery. Treatment of Crohns disease of the esophagus should primarily be medical and esophagectomy should only be considered in cases of complications, intractability or a suspicion of malignancy in the biopsied specimen.

Significance of the endothelial lining in prevention of intimal thickening of autogenous vein grafts in dogs

To better comprehend the role of the endothelial lining in occurrence and development of intimal thickening in arterially implanted autogenous vein grafts, two models of canine femoral arteries were prepared. In the Group I model, the implanted autogenous vein graft was kept under a normal flow condition for 2 to 4 weeks after implantation, then was exposed to an abnormal flow (poor run-off). In case of a 3- to 4-week normal flow, intimal thickening was practically nil. Scanning electron microscopic studies showed that this 3- to 4-week period corresponded to that of re-endothelialization of the autogenous vein grafts. Immunohistochemical studies of fibrinogen distribution in the autogenous vein graft wall in the Group II model revealed that the permeation of fibrinogen was enhanced in case of an abnormal flow condition for about 2 weeks after the implantation. We interpret these observations to mean that intimal thickening was induced by an accelerated permeability in the presence of abnormal flow conditions until full re-endothelialization after the implantation.

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.

Modified vein allograft for small arterial reconstruction in dogs

The ideal graft for peripheral arterial reconstruction has yet to be developed. We evaluated on the effectiveness of porosity to intimization of the graft. Modified vein allografts newly constructed through digestion of vein allografts with elastase, glutaraldehyde tanning and lyophilization were implanted in thirty-nine canine femoral arteries. These grafts had a higher porosity than conventional vein allografts and the overall patency rate was 70 per cent at 6 months after implantation. Microscopic examination showed that graft interstitial healing and subsequent intimization were completed by ingrowth of connective tissue from outside through the graft wall at 3 weeks and later. Aneurysmal change of the modified vein allografts was never evident. These results indicated that porosity of the graft is indeed an important factor for intimization and durability of grafts, even in bioderivative substitutes.