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Biomedical subjects

K Okadome

Publications and source records attributed to K Okadome.

At least 73 records · Page 4Linked to original sources
PubMed1985

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.

Animals↗
PubMed1984

A desktop computer to visualize the intraluminal velocity profile and its clinical application.

Based on our previous study that the outcome of reconstructive surgery for lower limbs could well be predicted by flow waveforms and that this state was defined by variation of wall shear stress (tau) in a cardiac cycle, we set up a desktop computer that could calculate wall shear stress in a given patient. This work is based on a principle of a computational method for simulating pulsating blood flow. The flow data from the patient are sent to the waveform analyzer, where the intraluminal velocity profile as well as the shear stress variation is demonstrated. Our study revealed no late occlusion in patients with flow waveforms over 70 dynes/cm2 in tau-variation, early graft failure in those below 20 dynes/cm2, and late occlusion in considerable numbers of patients whose waveforms were between 70 and 20 dynes/cm2. Intraoperative use of the waveform analyzer disclosed the occult cause of obstruction, which would otherwise be overlooked, leading to a remarkable decrease in the rate of immediate graft failure. Follow-up of outpatients with this approach facilitated early detection of late failure, making it possible to repair the graft with minor surgery. Use of the waveform analyzer proved superior to ankle pressure index in predicting graft failure.

Aged↗
PubMed1982

Skin sliding closure technique is effective for management of infected prostheses in cases of arterial reconstruction with synthetic grafts.

A clinical review of 400 prosthetic arterial reconstructions, carried out in the Second Department of Surgery of Kyushu University Hospital during a period from 1965 to 1981, revealed 10 graft infections (2.5 per cent). There were two out of 120 abdominal aneurysms (1.7 per cent) and 8 out of 260 aorto-femoral occlusive diseases (3.1 per cent). The contributing factors included intraoperative contamination with duodenal juice during surgery for abdominal aneurysms ruptured into the duodenum (2 cases), minor hematoma and/or lymphorrhoea at the groin or lower abdominal wall (5 cases), wound infection (1 case), compression necrosis of the sigmoid colon by the implanted graft (1 case) or perityphlitic abscess due to a perforating appendicitis (1 case). Bacteriologic examination revealed a predominance of a variety of staphylococcus at the groin or lower abdominal wall and E. coli in the abdominal cavity. Four patients expired. Limb amputation had to be done in 2, and 4 were cured. In the management of infected graft at the groin or lower abdominal wall, we used with success a skin sliding closure technique after continuous wound lavage in 3 patients.

Adolescent↗
PubMed1982

Intraluminal velocity profile analyzed from flow waveforms.

Normal and abnormal flow waveforms, electromagnetically measured in the reconstructed arteries of patients with peripheral occlusive diseases of the lower extremity, were analyzed in terms of luminal velocity profile, using a newly designed flow wave simulation pump. The blood flow with normal flow wave was characterized by a large fluctuation in the velocity profile in the limited layer adjacent to the wall, where a reversal stream was characteristically noted during the phase of cardiac diastole. In contrast, in the abnormal flow wave, the velocity profile in the limited layer adjacent to the wall was always stagnant with little change in the velocity during each phase of a cardiac cycle. These observations clearly explain why an artery with a normal flow waveform remains patent, while an artery with an abnormal waveform tends to occlude. It was also found that the electromagnetically determined flow waveforms do provide the required information on the luminal velocity distribution.

Adult↗
PubMed1981

Ultrasonic flow wave pattern as a prognostic indicator in peripheral arterial reconstruction.

A prognostic flowmetric study on 80 reconstructed arteries of the lower extremity was carried out to assess the flow wave patterns detected using a bidirectional doppler flowmeter. In 21 of 80 arteries, changes in the flow wave pattern were noted. For 10 of 21 affected arteries, an immediate arteriography revealed localized stenotic lesions at the distal anastomosis, in a short segment of the implanted autogenous vein graft or at the proximal host artery. Immediate repairs for the lesions were successfully performed by a minor surgery in 8 of 10 cases and the flow wave pattern reverted to normal. Two were not successful as the occlusion was complete before attempting the repair. The remaining 11 are now under conservative management as these patients refused further surgery. The ultrasonically driven flow wave pattern proved to be a useful indicator to assess the patency of the reconstructed peripheral artery to detect possible stenosis and thereby to take proper corrective measures and hence prevent a late occlusion.

Arterial Occlusive Diseases↗
PubMed1981

Effect of fibrin on arterial endothelial cells in vitro--an electron microscopic study.

An interaction between fibrin and arterial endothelial cells was studied in vitro electron microscopically by the modified method of Warren et al. Microvilli and cytoplasmic processes attached to fibrin threads in an early period of fibrinolysis and fibrin threads showed fine fibrillar or granular appearance in the lysed areas. Dilatation of endoplasmic reticulum and increase in number of intracytoplasmic vesicles, mainly in the luminal side of endothelial cells, were noted in the endothelial cells in the lysed areas. Fibrinolytically active endothelial cells were observed in 38 out of 100 endothelial cells of the rat aorta. Therefore, were suggest that microvilli of endothelial cells might play an important role in release of plasminogen tissue activator from the endothelial cells, and a heterogeneity of the endothelial cells exists in the reactivity to fibrin.

Animals↗
PubMed1976

Abdominal aneurysm with aortoduodenal fistula.

Two patients having the abdominal aneurysm with aortoduodenal fistula were treated surgically, but graft infection occurred. One patient died about 6 months after and the other about one year after the operation due to massive hemorrhage from the postoperative aortointestinal fistula. The difficulties in the treatment of the aortoduodenal fistula were discussed.

Aorta, Abdominal↗
PubMedDate not supplied

Hemodynamics and the development of anastomotic intimal hyperplasia of the polytetrafluoroethylene graft in dogs.

To clarify whether or not changes in wall shear stress play a determinant role in the induction of anastomotic intimal hyperplasia of polytetrafluoroethylene (PTFE) grafts, two experimental models were devised. Based on our previous study (J Vasc Surg, 1985), wall shear stress was defined by variation of wall shear stress (tau-variation) in one cardiac cycle. In experiment I, PTFE grafts were implanted into dogs under conditions of 85.2 +/- 36.2 ml/min of low flow rate with 66.7 +/- 31.1 dyne/cm2 of low tau-variation. In experiment II PTFE grafts were implanted under conditions of 10.1 +/- 4.6 ml/min of low flow rate with 120.4 +/- 37.2 dyne/cm2 of moderate tau-variation. The intimal thickness of 581 +/- 127 microns at one month and 1230 +/- 260 microns at three months implantation at the distal anastomosis under an abnormal flow condition in experiment I was statistically significant compared with findings in the case of 124 +/- 36 microns at 1 month and 171 +/- 74 microns at 3 months at the proximal anastomosis under an abnormal flow condition in experiment I, and with those of 164 +/- 68 microns at 1 month and 195 +/- 57 microns at three months at the distal anastomosis in experiment II (p less than 0.01). Under a normal flow condition, there was no evident intimal hyperplasia at proximal and distal anastomotic sites in experiment I. These observations are pertinent evidence that change in wall shear stress and not the rate of blood flow is the determinant factor related to development of intimal hyperplasia of PTFE grafts at the distal anastomosis.

Animals↗
PubMedDate not supplied

Evaluation of proposed standards for runoff in femoropopliteal arterial reconstructions: correlation between runoff score and flow waveform pattern. A preliminary report.

The Ad Hoc Committee on Reporting Standards of the Society for Vascular Surgery and the International Society for Cardiovascular Surgery (SVS/ISCVS) proposed a new angiographic scoring system that grades the quality of vessels distal to the expected bypass site and calculates an overall runoff score. To assess the predictability of the bypass grafts by this runoff scoring system, we compared this runoff score with postoperative increase in the ankle/brachial index (delta ABI) and intraoperatively measured flow waveform patterns in 60 patients undergoing femoropopliteal bypass grafts. No correlation was found between delta ABI and the runoff score. Graft-patent survival time correlated with the runoff score (r = 0.44, p = 0.02). Grafts with type 0 or I flow waveform pattern with a satisfactory long-term patency had a significantly lower runoff score than grafts with type II, III or IV flow waveform pattern (p less than 0.05). When all the grafts were arbitrarily divided into two groups (grafts with a runoff score over 4.5 and those with a score of less than 4.0), a superior long-term patency was obtained in the low runoff score group with polytetrafluoroethylene (p less than 0.01) and saphenous vein grafts (p = 0.04), but not in the group with composite grafts (p = 0.25). Thus, the SVS/ISCVS runoff scoring system can be used to predict the fate of bypass grafts in femoropopliteal arterial reconstructions.

Adult↗
PubMedDate not supplied

Ultrastructural evidence of the effects of shear stress variation on intimal thickening in dogs with arterially transplanted autologous vein grafts.

Based on our findings that changes in wall shear stress, not the rate of blood flow, were the main hemodynamic factor related to intimal hyperplasia of autologous vein grafts, we further investigated the effect of wall shear stress variation on sequential ultrastructural changes in the intimal hyperplasia of arterially transplanted autovein grafts, using canine models. As noted, wall shear stress variation (tau-variation) could be defined by the variation in wall shear stress within a cardiac cycle, using a desktop flow waveform analyzer. In Group I, which had a high flow rate of 78.4 +/- 4.6 ml/min and low tau-variation of 36.1 +/- 2.2 dynes/cm2, intimal hyperplasia was significant. Ultrastructurally, there was a marked transformation of intimal smooth muscle cells to secretory cells 2 to 4 weeks after implantation. The surface of the intima was lined with modified smooth muscle cells at 2 weeks after implantation. In Group II, which had a low flow rate of 5.6 +/- 2.2 ml/min and normal tau-variation value (174.6 +/- 13.0 dynes/cm2), intimal hyperplasia was minimal, and there were several layers of contractile type smooth muscle cells, with characteristic myofibrillae. The surface of the intima was lined with endothelial cells at 2 weeks after implantation. These findings suggest that, in regions of low wall shear stress variation, intimal smooth muscle cells of autovein grafts may well become secretory cells, and enhanced platelet adherence could occur during early intimal repair, causing intimal hyperplasia to develop.

Animals↗
PubMedDate not supplied

Successful simultaneous repair of coincidental bleeding malignant lymphoma of the stomach and expanding abdominal aortic aneurysm.

In a 61-year-old Japanese man, a concomitant bleeding gastric malignant lymphoma and expanding abdominal aortic aneurysm was evident. Bacterial studies were done for a further 32 laparotomy cases. The patient underwent abdominal aortic aneurysmectomy and partial gastrectomy simultaneously. The postoperative course was uneventful except for temporary pneumonia. The positive rate for bacterial culture in cases of gastric or colorectal cancers was significantly high compared with that in the cases of abdominal aortic aneurysm. From the viewpoint of bacterial contamination, these two operations should be done separately. However, simultaneous operations as in the current case are feasible if great care is taken.

Aorta, Abdominal↗
PubMedDate not supplied

Long-term results of arterial reconstruction of lower extremities determined by flow waveform analysis.

Arterial reconstructions of the lower extremities were reviewed to assess the usefulness of flow waveform analysis. Six hundred and thirty-four arterial reconstructions were divided into two groups: a former (1965-1973) group of 218 reconstructions not assessed by flow waveform analysis and a recent (1974-1985) group of 416 reconstructions analyzed according to flow waveform. The cumulative patency rates of the former and the recent group at 5 years were as follows: aorto-femoral, 75.2% and 86.7% (P less than 0.05); femoral-distal, 34.6% and 61.5% (P less than 0.001); extra-anatomical, 63.6% and 80.2% (P = 0.06), respectively. Based on the various flow waveforms evidenced intraoperatively, the cumulative patency rate of cases in the recent group with type 0 and I flow waveform was compared to the rate of those with type II flow waveform. The cumulative patency rates at 5 years were as follows: aorto-femoral, 92% and 82.7% (P = 0.15); femoral-distal, 77.7% and 49.3% (P less than 0.001); extra-anatomical, 91.8% and 68.9% (P less than 0.05), respectively. These results indicate that intraoperative flow waveform analysis is a simple and useful indicator for predicting the long-term results of arterial reconstruction.

Arterial Occlusive Diseases↗
PubMedDate not supplied

Correlation of long-term results of femoropopliteal autogenous vein grafts with shear stress variation. In situ or reversed graft?

To investigate the correlation between blood flow rate and shear stress variation (tau-variation), the integral of time differential of wall shear stress in one cardiac cycle and the outcome of the vein graft, 42 consecutive patients with femoropopliteal autovein grafts (24 in situ and 18 reversed grafts) were followed for 3 months to 5 years after surgical repair. No correlation was noted between the intraoperative blood flow rate and the outcome of the vein grafts with either procedure. In contrast, the tau-variation value of the vein grafts was closely related to their outcome with both procedures. The higher the tau-variation, the better the long-term results. Vein grafts with a tau-variation of over 60 dyn/cm2 showed good long-term results. The in situ grafts tended to have a higher tau-variation than the reversed grafts (67% in the in situ grafts vs 39% in the reversed grafts). Late failures were noted in vein grafts with low tau-variation value within 3 years after surgery. We recommend the in situ graft technique for patients undergoing femoropopliteal reconstruction, with careful follow-up in cases of vein grafts with a low tau-variation value.

Adult↗
PubMedDate not supplied

Aneurysm in a double velour knitted Dacron graft.

Double velour knitted Dacron grafts are currently used for aorto-iliac arterial reconstructions to increase encapsulation and enable rapid intimization of the grafts. Reports of an aneurysm arising in the body of a double velour knitted Dacron graft are rare. We experienced a case of aneurysm arising in the body of an innominate-abdominal aortic bypass graft four years after implantation. Microscopically, this focal aneurysm seemed to be related to a structural defect in the manufacturing process. We wish to stress that patients with implanted commercial Dacron prostheses should be carefully and regularly followed.

Adult↗