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T Onohara

Publications and source records attributed to T Onohara.

At least 37 records · Page 2Linked to original sources
PubMed1996

Long-term results and prognostic factors after repair of abdominal aortic aneurysm with concomitant malignancy.

OBJECTIVE: Long-term results after repair of abdominal aortic aneurysm (AAA) with concomitant malignancy were reviewed, and factors which may affect survival were analyzed. DESIGN: Retrospective series with follow-up of three to 125 months. Setting. Department of Surgery, Matsuyama Red Cross Hospital, Matsuyama, Japan. PATIENTS: Among 112 consecutive repairs of AAA, 16 cases had concomitant malignancy. The malignant lesions included eight gastric cancers and eight other malignant tumours. The malignancies were divided using TNM Classification into an early stage (stage O or I) group (n=9) and an advanced stage (stage II, III, or IV) group (n=7). INTERVENTIONS: All aneurysms were successfully repaired, and simultaneous resection of the concomitant malignancy was performed in five cases. While 13 malignant lesions were resected completely, three could not be resected completely, but were treated by other surgical procedures. MEASURES: Survival rates were predicated using the Kaplan-Meier method. The log-rank test was used to compare survival rates. RESULTS: The one-, two-, and five-year survival rates after repair of AAA were 80%, 72% and 63%, respectively. The survival rates for the early stage group were significantly higher than those for the advanced stage group (p<0.05). Patients with concomitant gastric cancer or who underwent complete resection of the malignant lesion survived longer. CONCLUSION: In patients with concomitant AAA and malignancy, factors influencing survival for those with malignant lesions also affected survival after aneurysmectomy. Detection of early-stage concomitant malignancy and more aggressive treatment for the malignancy may improve the outcome.

Age Factors↗
PubMed1995

Late graft failure of autologous vein grafts for arterial occlusive disease: clinical and experimental studies.

Late graft failure following arterial reconstructive surgery, especially after infrainguinal reconstruction, remains a major concern for vascular surgeons. To more effectively predict the outcome of reconstructed arteries, we herein propose an intraoperative flow waveform analysis which correlates well with the long-term patency rate of grafts. According to this flow waveform analysis, late graft failure was occasionally seen in grafts with type II waveforms when poor distal runoff vessels had been shown by the preoperative arteriogram. Next, to investigate which events occurring in autologous vein grafts under abnormal hemodynamics may contribute to late graft failure, a distal poor-runoff model was made in the canine femoral artery. In this review, we present the results of our investigation on autologous vein grafts using this poor-runoff model. We also relate our recent findings on the function of regenerated endothelium in autologous vein grafts.

Animals↗
PubMed1994

Blood flow and kinetics of smooth muscle cell proliferation in canine autogenous vein grafts: in vivo BrdU incorporation.

The effects of blood flow on the kinetics of smooth muscle cell (SMC) proliferation were examined in canine autogenous vein grafts with a distal poor run-off model. The in vivo bromodeoxyuridine (BrdU, a thymidine analogue) incorporation method was used to label proliferating SMCs in each layer of the vein graft. The BrdU labeling index (LI) was defined as a percentage of labeled cells compared to the total number of SMCs, and BrdU LIs were measured in the media and the intima of the graft. The development of intimal thickening of grafts was accelerated at 2 to 4 weeks after implantation. In poor run-off limbs with an abnormal blood flow condition, as characterized by a low flow and a low shear stress variation, the intima of the graft thickened more progressively than that in control limbs with a normal blood flow. In both groups, the medial BrdU LIs reached a maximum 3 to 5 days after implantation and decreased thereafter. The peak of the intimal BrdU LIs occurred at 1 week in both groups. The intimal LIs of the grafts in poor run-off limbs (6.34% at 1 week and 2.97% at 2 weeks) were significantly higher than those in control limbs (5.34 and 1.98%) for 2 weeks after implantation (P < 0.05). The medial SMC proliferation and the following intimal SMC proliferation of vein grafts were accelerated prior to development of the intimal thickening. SMC proliferation in the intima was prominent in a poor run-off limb with a low flow and a low shear stress variation.

Animals↗
PubMed1993

The reversibility of impaired prostacyclin production of the vein graft.

The effects of changes in shear stress (shear stress variation) on production of prostacyclin (PGI2) were examined in canine autologous vein grafts, which were implanted in the poor or normal distal runoff limbs. Four weeks after grafting, the vein grafts were perfused ex vivo and PGI2 was assayed as 6-ketoprostaglandin F1 alpha. The vein grafts were perfused under constant flow for the first 30 min and then under pulsatile flow simulating an abnormal flow with a low shear stress variation or a normal flow with a high shear stress variation for the next 30 min. Basal production rates (30-min cumulative PGI2 production) of vein grafts implanted in the poor runoff and normal runoff limbs were 1.97 +/- 0.71 and 2.19 +/- 0.40 ng/cm2, respectively, with no significant difference. Pulsatile flow effects (increased PGI2 production between 30 and 60 min) of simulated abnormal versus normal flow were 0.50 +/- 0.50 ng/cm2 versus 2.31 +/- 1.87 ng/cm2 in vein grafts implanted in poor runoff limbs (P < 0.05) and 0.48 +/- 0.41 ng/cm2 versus 3.48 +/- 1.08 ng/cm2 in vein grafts implanted in normal runoff limbs (P < 0.01), respectively. There were no significant differences in simulated normal flow effects between poor runoff limbs and normal runoff limbs. The results indicate that the release of PGI2 in vein grafts may decrease in the presence of an abnormal blood flow with a low shear stress variation. In addition, it is suggested that even vein grafts implanted in the poor runoff could increase PGI2 production once the grafts were placed into normal arterial circulation.

Animals↗
PubMed1993

Impaired endothelial prostacyclin production of the canine vein graft in a poor distal runoff limb.

BACKGROUND: Because blood flow modulates endothelial prostacyclin production, the extent of this production in autologous vein grafts implanted in poor distal runoff limbs needed to be examined. METHODS: Endothelial prostacyclin production in canine autologous vein grafts was measured in poor distal runoff limbs (poor runoff group) and compared with findings in normal runoff limbs (control group). Vein grafts were perfused in a closed circuit at 3 days and 1, 2, 3, and 4 weeks after implantation; after perfusion for the first 30 minutes in a steady flow (basal prostacyclin production), the grafts were exposed to arachidonic acid (stimulated prostacyclin production) for the following 30 minutes. Prostacyclin, as the metabolite 6-keto-PGF1 alpha, was radioimmunoassayed. RESULTS: Basal and stimulated prostacyclin production increased in both groups during a period of time after implantation. At 2 weeks when endothelialization was complete, prostacyclin production in the poor runoff group was impaired, compared with the findings in the control group, and this difference increased with time. At 4 weeks the stimulated prostacyclin production was 18.91 +/- 4.03 ng/cm2 in the control group and 11.60 +/- 1.67 ng/cm2 in the poor runoff group (p < 0.05). CONCLUSIONS: We propose that the impaired capacity of the vein graft to produce prostacyclin in a poor distal runoff may lead to loss of graft patency in reconstructed arteries.

Animals↗
PubMed1992

Thrombolytic therapy of synthetic graft occlusions before vascular reconstructive procedures.

The objective of this study was to evaluate the impact of thrombolysis of synthetic grafts before urgent vascular reconstruction. In 29 patients, 41 thrombosed synthetic grafts that underwent intraarterial thrombolysis were studied. The cases were divided into three groups: group I--complete thrombolysis followed by reconstruction; group II--complete thrombolysis alone; and group III--incomplete lysis requiring reconstruction or sympathectomy. Follow-up ranged from 1 to 556 days (mean: 149 days). Kaplan-Meier analysis was used to determine patency and limb salvage rates. One-year patency and limb salvage rates were 53% and 95%, 34% and 67%, and 38% and 48%, respectively, for groups I, II, and III. Eighteen complications occurred in 16 of the 41 (39%) episodes. One patient died of intracranial hemorrhage. The best results were achieved when complete lysis was followed by appropriate reconstruction. Patency was equally poor in complete thrombolysis alone and reconstructions required by incomplete thrombolysis. Limb salvage was better after complete thrombolysis, regardless of the appropriate reconstruction.

Aged↗
PubMed1992

High aortic occlusion associated with lupus anti-coagulant.

Lupus anti-coagulant (LAC) has been recognised in association with venous and arterial thrombotic events. We retrospectively investigated the relationship between LAC and 21 patients with juxtarenal high aortic occlusion. Four of the 21 patients were LAC positive (19%), one of whom was a woman suffering from systemic lupus erythematosus (SLE). The three men had neither SLE nor any other connective tissue disease. The mean age of the four patients was 43.5 years and three of them (75%) were younger than 50 years of age. By contrast, the mean age of the 17 patients without LAC was 59.9 years and 14 of them (82.4%) were older than 50 years. The postoperative courses in all four patients with LAC undergoing arterial reconstructions were uneventful. Two patients were treated by either anti-coagulation or anti-platelet agents, postoperatively. The present paper demonstrates for the first time that, in patients with juxtarenal high aortic occlusion, the incidence of LAC positivity is higher in younger patients (below 50) than in older patients (above 50). In addition, our results show that a preoperative evaluation of the presence of LAC is required in cases with juxtarenal high aortic occlusion, particularly when the partial thromboplastin time (PTT) is prolonged and the patients are younger than 50 years old.

Adult↗
PubMed1992

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.

Aged↗
PubMed1992

Clinical experience with polytetrafluoroethylene (PTFE) in the aortobifemoral position.

Between 1981 and 1990, 18 patients (mean age 66.0 years) had aortobifemoral bypass with polytetrafluoroethylene (PTFE) bifurcated grafts. Twelve patients (66.7%) were treated for aortoiliac occlusive disease, 5 patients (27.8%) for abdominal aortic aneurysms and one patient (5.6%) had surgery for hypoplastic aortic syndrome. The authors' overall complication rate was 16.7 per cent and included formation of an anastomotic pseudoaneurysm (1/18, 5.6%), graft infection (1/18, 5.6%), and graft thrombosis (1/18, 5.6%). Sixteen patients were followed for a mean period of 41.4 months. In this subgroup of patients the patency rate was 93.8 per cent. The authors conclude that the PTFE bifurcated graft is a suitable conduit for use in aortobifemoral bypass surgery.

Aged↗
PubMed1991

Intraoperative flow waveform analysis aids in preventing early graft failure following reconstruction of arteries of the legs.

To enable early detection and treatment of vascular defects leading to early graft failure, intraoperative flow waveform analyses were carried out during lower extremity arterial reconstructions in 226 patients undergoing 102 aortoiliac/femoral and 124 femorodistal bypass grafts. Flow waveform types III or IV indicated early graft failure. These were noted in seven grafts (6.9%) in the aortoiliac/femoral position and in eight grafts (6.5%) in the femorodistal position. The main cause of the abnormal flow waveform pattern was misinterpretation of preoperative arteriographic findings in aortoiliac/femoral reconstructions and technical errors in anastomoses in femorodistal reconstructions. Of 15 grafts with an abnormal flow waveform pattern, 13 were effectively repaired with patch angioplasty, graft extension, or replacement with thrombectomy. In two grafts, the repair failed and amputation had to be done. Thus, intraoperative flow waveform analysis is a simple, useful, and safe method to detect vascular defects leading to early graft failure. Unless assessment of preoperative arteriographic findings in aortoiliac/femoral reconstructions are accurate and anastomotic techniques in femorodistal reconstructions are refined, early graft failure may occur.

Aged↗
PubMed1991

Laser thermal angioplasty for early repair of anastomotic stenosis after lower extremity arterial reconstruction: initial experience.

Laser thermal angioplasty with a sapphire hot-tip Nd-YAG laser system was effectively used for five grafts with anastomotic stenotic lesions which occurred after femoro-popliteal arterial reconstructions. Stenotic lesions were detected by a combination of Doppler flow waveform analysis and ankle/brachial index measurement in 32 femoro-popliteal and five femoro-tibial arterial bypass grafts in the postoperative period. The laser probe used was 3 to 4 mm in diameter. There were no perforations of the arterial wall caused by thermal ablation, even with repeated pulses of 40 watts of laser energy for 3 s. Contact Nd-YAG laser thermal angioplasty using this rounded, 3-4 mm hot-tip facilitated effective widening of the lumen of the anastomotic stenotic lesion. All patients remain well at follow-up from 9 to 20 months after laser thermal angioplasty.

Aged↗
PubMed1991

Simulated blood flow and the effects on prostacyclin production in the dog femoral artery.

Effects of blood flow on the production of prostacyclin (PGI2) were examined in the canine femoral artery perfused ex vivo. Each artery was perfused in situ with medium 199, under conditions of simulated blood flow. To simulate the normal and abnormal blood flow waveforms at the same mean flow rate, we developed a flow apparatus capable of making various waveforms by changing the duration when the electromagnetic valve in the circuit was open. Group I (n = 7) was exposed to a steep acceleration waveform followed by a steep deceleration, as the normal flow waveform; group II (n = 7) was exposed to a gentle sloping waveform in the deceleration phase, as the abnormal flow waveform. PGI2 was measured as 6-ketoprostaglandin F1 alpha. PGI2 production was estimated as the cumulative production for the first 5 minutes (acute response) and as the production rate after the first 30 minutes (stable production rate). Under conditions of normal flow, the acute response was 5.87 +/- 2.16 ng/cm2/5 min, whereas under conditions of abnormal flow, the rate was 2.20 +/- 0.27 ng/cm2/5 min (p less than 0.01). Stable production rates were 82.5 and 37.5 pg/cm2/min, respectively (p less than 0.05). Both the acute response and the stable production rate of PGI2 production were greater under conditions of simulated normal flow as compared with findings in the case of an abnormal flow. Our working hypothesis is that the decreased production of PGI2, as well as a deterioration in the implanted graft, under conditions of abnormal blood flow leads to a loss of late patency of the reconstructed arteries.

6-Ketoprostaglandin F1 alpha↗
PubMed1990

Flow waveform analysis and long-term results of autogenous saphenous vein and polytetrafluoroethylene grafts in 140 arterial reconstructions of the lower limbs.

In previous work we have found that the outcome of grafts in the lower limbs correlated with the flow waveform pattern of the artery. We have retrospectively reviewed 140 femoro-popliteal bypass operations involving the use of 75 saphenous vein grafts and 65 polytetrafluoroethylene (PTFE) grafts. For grafts with type 0 or I flow waveform pattern the patency at 4 years (56%) was superior to grafts with the type II, III or IV flow waveform (35%) patterns (P less than 0.05). For saphenous vein grafts with type 0 or I flow, the patency rate was 78% at 3 years and 69% at 5 and 8 years. In contrast with type II, III or IV flow the patency rate was 52% at 3 years, 48% at 5 years and 34% at 8 years, with a statistical significance at 4 years (P less than 0.05). PTFE grafts with type 0 or I flow showed a tendency toward an increased patency which was not significant in comparison with the grafts with type II, III or IV flow (P = 0.12). Saphenous vein grafts with type II flow patterns had an increased occlusive rate in the first year whereas PTFE grafts had the same tendency within 2 years. In both types of graft, early occlusions within a month of operation were encountered in grafts with a type III or IV flow waveform pattern. These results indicate that the fate of the reconstructed arteries of the lower limb could be predicted by flow waveform analysis, and a careful and serial postoperative evaluation of the graft should be made, particularly those with type II, III or IV flow waveform patterns.

Blood Vessel Prosthesis↗
PubMed1990

Intimal thickening and permeability of arterial autogenous vein graft in a canine poor-runoff model: transmission electron microscopic evidence.

The relationship between development of intimal thickening and permeability of an arterial autogenous vein grafts in dogs' limbs was examined with horseradish peroxidase used as a tracer. The transendothelial transports increased under conditions of abnormal blood flow, compared with findings with a normal blood flow, and a large amount of horseradish peroxidase infiltrated the subendothelial spaces for 4 weeks after implantation, a time when intimal thickening progressed rapidly. It would thus appear that, under conditions of abnormal blood flow, intimal hyperpermeation would be a contributing factor to the intimal thickening of an autogenous vein graft before an autovein graft had completely adapted to the new environment.

Animals↗
PubMedDate not supplied

Pre-operative imaging can diagnose torsion of the gallbladder: report of a case.

Torsion of the gallbladder is a rare disease and pre-operative diagnosis of the disease is uncommon. About 400 cases have been reported, but only 4 were diagnosed by pre-operative imaging. We report on a case of gallbladder volvulus diagnosed pre-operatively using pre-operative imaging with ultrasound and computed tomography.

Aged↗
PubMedDate not supplied

Clinicopathological features of long-term survivors of scirrhous gastric cancer.

BACKGROUND/AIMS: Prognosis of scirrhous gastric cancer remains low. To determine the clinicopathological features that are correlated with prognosis, we studied long-term survivors of scirrhous gastric cancer (survival duration more than 5 years) in comparison with patients with short survival. METHODOLOGY: Among 2719 gastric cancer patients who underwent surgery at Matsuyama Red Cross Hospital, 211 cases were diagnosed as scirrhous type gastric cancer. Seventeen patients survived more than 5 years, and the rest had short survival (less than 5 years). Comparison of clinicopathological factors was done by chi 2 analysis. Multivariate analysis was done in order to focus on the prognostic factors. RESULTS: The 5-year survival of the total 211 patients was 12%. The 5-year survival of patients who underwent curative surgery (67 cases) was 30%, which was significantly higher than that of the non-curative surgery group (144 cases, 6%). Significant differences were noted in the following variables: peritoneal dissemination, hepatic metastasis, lymph node dissection, pattern of infiltrating growth, depth of invasion, histological lymph node metastasis, histological stage, and histological curability. Patients with either hepatic metastasis or peritoneal dissemination did not survive 5 years. Multivariate analysis revealed that the most significant independent prognostic factor was histological curability, followed by peritoneal dissemination. CONCLUSIONS: There is a possibility of long-term survival for patients with scirrhous gastric cancers without hepatic metastasis, peritoneal dissemination, or extensive lymph node metastasis. Curative surgery is important, suggesting that the extended operation is rational if possible.

Adenocarcinoma, Scirrhous↗