DUPLEX SCAN SURVEILLANCE OF INFRA-INGUINAL BYPASS GRAFTS

Duplex scanning, which allows ultrasonic imaging of blood vessels and coincident Doppler qualification of the velocity of blood flow within those vessels, has been developed and refined over the past 10–15 years. Although operator-dependent, vascular surgeons recognize it as one of the most significant recent contributions to the everyday practice of modern vascular surgery when performed by experienced personnel. For example, it is now accepted as the investigation of choice for the non-invasive diagnosis of carotid bifurcation disease with an increasing number of surgeons avoiding cerebral angiography prior to carotid endarterectomy. It has almost completely superseded venography as the investigation of choice for suspected deep venous thrombosis. Its application to surveillance following arterial reconstructions is logical, particularly for those placed in the leg (femoro-popliteal/crural bypass) and even more particularly for those bypasses lying in the subcutaneous plane (in situ saphenous vein).     

DUPLEX SCAN SURVEILLANCE OF INFRA-INGUINAL BYPASS GRAFTS: THE CASE FOR SELECTIVITY

A consecutive series of 270 non-reversed infra-inguinal saphenous vein bypass grafts performed by the same surgeon between January 1986 and January 1991 was reviewed. The series included 250 in situ and 20 translocated non-reversed grafts. The aims were to calculate the number of duplex scans that would have been required for surveillance, to determine the value of a non-selective prolonged scanning regimen and to identify subgroups requiring more (or less) intensive surveillance. Indications were for critical ischaemia in 194 patients, popliteal aneurysms in seven patients and incapacitating claudication in 69 patients. Patients were reviewed at 1 month and then at approximate 6 month intervals for symptoms and with resting and post-exercise ankle pressures. Primary patency of grafts placed to a popliteal distal anastomosis for critical ischaemia was 85% (s.e.m. 9.1%) at 3 years while secondary patency was 94% (s.e.m. 8.1%) at 4 years. Primary patency of grafts placed to a tibial artery or isolated popliteal segment was 68% (s.e.m. 8.4%) at 2 years while secondary patency was 76% (s.e.m. 9.9%) at 2.5 years. The difference in secondary patency between popliteal and tibial grafts was highly significant (P= 0.003). Tibial grafts required significantly more secondary early intervention than popliteal grafts. If recommended protocols for serial duplex scan (DS) surveillance had been followed, a minimum of 960 scans would have been required. If the tibial bypass group only had been monitored, 702 of these scans would have been avoided with a maximum loss of one popliteal graft and no limbs. This study suggests that non-selective DS surveillance in ambulant asymptomatic patients with a popliteal distal anastomosis may not be justified. Both early and intensive surveillance of tibial grafts appear justified.     

THE VALUE OF DUPLEX SCANNING IN SURVEILLANCE OF INFRA-INGUINAL VEIN AND SYNTHETIC GRAFTS

The contribution of duplex scanning to improving early diagnosis of graft stenosis was evaluated in 195 patients after infra-inguinal bypass procedures. Over a 31 month period, 406 duplex scans were obtained on 232 limbs with 191 vein and 41 polytetrafluoroethylene (PTFE) grafts. Peak systolic velocities > 200cm/s with spectral broadening and lumen reduction on B-mode image were the criteria adopted for identification of a haemodynamically significant (> 50%) stenosis. Sixty-one stenoses were identified in 55 of the grafted limbs. Thirty-three of the 55 limbs had a subsequent angiogram. The angiogram showed graft occlusion in six limbs, graft stenosis in 18, and native artery stenosis in four. Twenty-one of the grafts had the angiogram within 1 month after the duplex had detected graft stenosis, and one (4.76%) became occluded in this interval. Seven had an angiogram more than 1 month after the duplex study, and five (71.4%) had become occluded. The angiographic study did not confirm a graft stenosis in five limbs. Three were submitted to operation and stenosis was confirmed. Seventeen graft thromboses were detected by duplex scanning. Graft thrombosis was demonstrated following a previous negative duplex scan in one of the 106 vein grafts (0.94%), and in four of 30 PTFE grafts (13.3%). Duplex scanning is effective in the detection of graft stenosis. The precise anatomical location is less accurate when in the region of an anastomosis. Early attention should be taken when duplex studies suggest critical graft stenosis because there is a high risk of occlusion. Polytetrafluoroethylene grafts tend to thrombose without a precursory focal stenosis.     

AXILLOFEMORAL ARTERIAL BYPASS GRAFTS

The results of 24 axillofemoral arterial bypass grafts performed over a five-year period are presented. This extraanatomical technique of arterial reconstruction is valuable following removal of an infected aortic Dacron graft and for limb salvage or severe intermittent claudication in selected poor-risk patients with aortoiliac occlusive disease. There were few early complications and the early patency rate was excellent, but the long-term success of the operation is uncertain.     

SHOULD PERI-OPERATIVE INFRA-INGUINAL GRAFT DUPLEX SCANS BE ROUTINELY PERFORMED?

Background : The ability of duplex ultrasound graft surveillance to detect graft stenosis is well documented. However, the optimal time to commence duplex ultrasound graft surveillance is not clear. Methods : An early duplex ultrasound study was performed on 90 infra-inguinal bypass grafts within 2 weeks of surgery. Further duplex scans were performed at intervals after surgery of 1 month, 3 months, 6 months, 1 year and then annually. An ankle/brachial systolic pressure index (ABI) was performed before the infra-inguinal bypass and then 24 h after the surgery. The ABI was also routinely measured at the time of each graft duplex examination. Results : Six graft thromboses (6.7%) were demonstrated on the first graft duplex within 2 weeks of the surgery. The 24-hour postoperative resting ABI were less than 0.5 in all six cases. Significant graft stenoses (> 50%) or native artery diseases were detected in six cases (6.7%) on the first graft scan (proximal anastomosis stenosis, 1; mid-graft stenosis, 3; peroneal artery stenosis, 1; popliteal artery occlusion, 1). The resting ABI was less than 0.5 in one of these cases. Vein patch angioplasty was performed on graft stenosis in two cases following the first duplex scan. In 78 cases with either normal or minimal graft/native artery stenosis (< 50%), the resting ABI were less than 0.5 in only two cases (2.6%). The first graft duplex ultrasound examinations were technically difficult or gave a poor image in 21 cases (23.3%). During the subsequent graft duplex follow-up, seven graft thromboses were demonstrated at an average of 5.9 months after surgery (1–12 months). Significant stenosis (> 50%) was demonstrated in 10 additional cases at an average of 8.5 months after surgery (1–12 months). Conclusions : The data of the present study do not support routine peri-operative graft duplex scanning in addition to a 1-month graft duplex scan. Early postoperative resting ABI should be routinely performed. If the resting ABI is less than 0.5, an immediate duplex scan should be carried out to assess graft integrity. A long-term non-invasive graft surveillance programme is important in the detection of graft stenosis.     

OBTURATOR FORAMEN BYPASS IN THE MANAGEMENT OF INFECTED PROSTHETIC VASCULAR GRAFTS

The obturator foramen bypass graft remains an excellent option for revascularking the lower extremity when dealing with an infected prosthetic vascular graft in the groin. In this series, six obturator foramen bypass grafts were performed in five patients for infectious groin complications following vascular surgery. Conservative measures such as local antibiotic irrigation and abscess drainage designed to preserve the graft in situ had failed to eradicate the infection in all instances and was complicated by suture-line haemorrhage in three instances. An aggressive approach should be adopted, aimed at excision of the infected graft. The obturator foramen bypass graft remains a durable graft for limb salvage. Five out of six obturator foramen bypass grafts were patent after 11–26 months follow up.     

A COMPARISON BETWEEN SAPHENOUS VEIN AND DACRON VELOUR GRAFTS FOR FEMOROPOPLITEAL BYPASS

One hundred and thirty-eight femoropopliteal grafts were performed for arteriosclerotic occlusive disease of the femoral artery in a five-year period. One group of patients who had 81 saphenous vein grafts was compared with a similar group who had 57 Dacron Velour grafts. At three years 90% of the vein grafts were patent, compared to 45% of the Dacron Velour grafts. Twenty-seven per cent of all patients presented with threatened limb loss. Amputation was averted in all but 5%. Intraoperative flow measurement did not prove to be a reliable indicator of long-term patency.     

A RETROSPECTIVE ANALYSIS OF INFRA-INGUINAL ARTERIAL RECONSTRUCTION: THREE YEAR PATENCY RATES

Primary infra-inguinal arterial reconstructions were reviewed for primary patency and outcome of thrombosis in 144 patients. Distal anastomoses in these patients were to the popliteal artery and were above the knee in 63, below the knee in 53 and at the tibial level in 28. The treatment used was: polytetrafluoroethylene (PTFE) in 33 cases, PTFE with an interposition vein cuff in 29 cases, autogenous saphenous vein (ASV) in situ in 47 cases, and reversed technique in 26 cases. Life table analysis showed a 59% overall primary patency at 3 years. Patency rates of above knee anastomoses (65%) and below knee (61%) were statistically different from the tibial anastomoses (42%. P = 0.005). In both above and below knee popliteal anastomoses there was a statistically significant difference in the patency of ASV and the PTFE/vein cuff technique (P= 0.0006) but there was no difference between ASV and FTFE. There was no difference in patency rates for the various types of grafts with tibial anastomoses. Data were analysed at 3 years, taking into account the variables of smoking, diabetes or indications for surgery respectively and no difference was found in patency. The number and calibre of the run-off vessels did not influence patency significantly, hence anastomosis to any good quality vessel regardless of run-off is recommended. The poor results with the interposition vein cuff technique are unexplained but this study suggests that the technique should he reserved for anastomoses below the popliteal artery.     

三种骨移植材料大鼠体内植入的组织学观察

目的 比较3种骨移植材料在大鼠体内降解吸收及诱导周围组织反应的情况,为临床骨缺损修复选择合适的骨移植材料提供理论依据.方法 将36只健康成年SD大鼠(体重229～358 g)随机分为A、B两组,每组18只,于大腿中部切开长约2 cm切口,造成股部肌袋,埋植不同实验材料.A组左侧植入人工骨硫酸钙(calcium sulfate,CS)颗粒(A1组),右侧植入同种异体脱钙骨基质(demineralized bone martrix,DBM)材料(A2组);B组左侧植入异种DBM(B1组),右侧不植入任何材料作为空白对照(B2组).术后2、4、6周,A、B组各处死6只动物取材,行大体观察和组织学观察,并行组织学评分.结果 大体观察:A1组CS颗粒随时间延长逐渐降解吸收:A2组和B1组DBM未见明显吸收,肌肉有纤维化改变,炎性反应均较重;B2组仅见术区组织瘢痕改变.组织学观察:A1组未见明显炎性反应,CS颗粒随时间延长逐步降解吸收,于术后6周完全降解吸收,后期周围组织纤维化表达增加;A2组和B1组炎性反应随时间延长而减轻,DBM降解吸收不明显,可诱导异位肉芽组织并继发纤维化改变,未见明显免疫反应并可观察到异位诱导成骨现象;B2组轻微炎性反应随时间延长而消退,后期有胶原纤维密度增加和血管化发生.A2、B1组与A1、B2组炎性浸润评分比较差异均有统计学意义(P<0.05),A2、B1组间及A1、B2组间差异无统计学意义(P>0.05).A1、A2、B1组纤维化表达随时间延长而增加,与B2组比较差异均有统计学意义(P<0.05);A1、A2及B1组间差异无统计学意义(P>0.05).结论 CS降解吸收快,生物相容性好,在急性骨折伴缺损和无需承重部位的骨移植中是最佳骨修复填充材料.同种异体和异种DBM具有生物相容性和骨诱导活性,吸收缓慢,适合于下肢承重部位骨缺损和骨不连的修复治疗.     

新型表皮细胞生物膜移植物的研究

目的将人表皮细胞接种到生物膜上构建一种新的表皮替代物———表皮细胞生物膜移植物（ＭＣＧ）。方法新鲜和冷冻保存的ＭＣＧ移植到裸鼠全厚皮肤缺损创面，以单纯无接种细胞的生物膜作为对照。并行组织学、免疫组织化学及电镜观察。结果表皮细胞可以生物膜为载体在体外进行培养，达６０％～７０％亚饱和状态时，表皮细胞生物膜可一起移植到创面，在创面上表皮细胞继续增殖分化，形成一层新生表皮。结论表皮细胞生物膜移植物可作为一种新型表皮替代物修复皮肤缺损     

POLYTETRAFLUOROETHYLENE (PTFE) GRAFTS FOR HAEMODIALYSIS: PATENCY AND COMPLICATIONS COMPARED WITH THOSE OF SAPHENOUS VEIN GRAFTS

A comparison has been made between polytetrafluoroethylene (PTFE) and saphenous vein as graft material for the construction of arteriovenous fistulas for use in haemodialysis. Fifty patients with PTFE grafts have been examined and compared with 70 patients with saphenous vein grafts. At eighteen months the accumulative patency rate was 69.8% for PTFE grafts and 68.9% for saphenous grafts. Although the PTFE grafts were similar in terms of patency, their complication rate was higher. The infection rate and distal ischaemia rate for PTFE grafts were double those of the vein grafts. Two patients developed median and ulnar nerve paralysis respectively shortly after implantation of PTFE grafts. Because of this it is recommended that their use be restricted to the lower limb. Despite a higher incidence of complications, PTFE grafts are a satisfactory substitute if a suitable saphenous vein is not available.     

应用胎儿神经修复周围神经缺损

报告应用经冷藏的胎儿坐骨神经移植修复周围神经缺损,其中胎儿神经修复腓肠神经供区缺损5例,修复手指固有神经缺损2例,计3指4侧,经随访1年,均恢复了较好的感觉功能。介绍了手术方法,讨论了胎儿神经移植的价值等。     

EXPERIMENTAL SKELETAL MUSCLE GRAFTS AS A MODEL OF REGENERATION

Background : It is now well established that mature skeletal muscle has the ability to regenerate, and reports on this phenomenon have existed in the research literature for some 40 years. However, it is only relatively recently, largely due to the advances in microsurgery, that practising surgeons can make direct use of the regenerative ability of skeletal muscle. Methods : Most of the key data on skeletal muscle regeneration have come from experimental studies on muscle grafts in small animal models. One such model is the transplantation of the extensor digitorum muscle of the mouse or rat into the contralateral site, or the relocation of this muscle onto the surface of the tibialis anterior muscle. These and other models, together with the important cellular mechanisms involved in the regeneration of skeletal muscle, are reviewed briefly in this article. Results : Skeletal muscle cells regenerate rapidly in muscle grafts, arising from satellite cells in the surviving peripheral fibres of the graft within 2 days after grafting. The resultant myoblasts progress towards the necrotic graft centre and occupy the area by 5 days. Revascularization commences at 3 days after grafting, but reinnervation takes many weeks to complete. Conclusions : With the established knowledge on skeletal muscle regeneration, largely gained from experimental studies of muscle grafts, an understanding of these mechanisms should now be fundamental knowledge for today's practising surgeons.     

DUPLEX ULTRASOUND ASSESSMENT OF THE VENOUS STATUS OF THE SWOLLEN LEG

Between January 1991 and December 1993, duplex ultrasound characterization of venous disease in leg swelling was studied in 214 patients (261 limbs; 167 unilateral and 47 bilateral). All patients were examined with a duplex scanner, the superficial and deep venous systems were evaluated for the presence of thrombus and valvular incompetence. Of the 261 limbs, 29 (11.1%) had deep venous thrombosis, 14 (5.4%) had superficial venous thrombosis, 66 (25.3%) had deep venous incompetence (31/66 limbs also had superficial venous incompetence), 65 (24.9%) had incompetence in the superficial veins only. and five (1.9%) had deep venous obstruction resulting from a popliteal cyst or a popliteal vein ligation. Eighty-two limbs (31.4%) had no evidence of venous obstruction or incompetence at the areas evaluated. This study showed that venous obstruction and valvular incompetence had occurred in two-thirds of swollen legs examined. Some of the venous obstructions resulted from surgically treatable diseases such as a popliteal cyst, and some of the venous disorders involved the superficial venous system only. Complete venous evaluation with duplex imaging can be very helpful in the determination of the underlying cause of the swelling.     

SURGICAL BYPASS FOR PALLIATION OF MALIGNANT OESOPHAGEAL OBSTRUCTION

It is possible to achieve satisfactory palliation for most patients with malignant oesophageal obstruction by endoscopic means, surgical resection or radiotherapy. Despite these options, a small group of patients remains for whom another alternative should be considered. Fifteen patients presenting with extensive tumour, a non-dilatable stricture, or a tracheo-oesophageal fistula, not suitable for any of the standard methods of palliation, underwent palliative surgical bypass using stomach or colon. The hospital mortality was 33% and the median survival 6 months. Anastomotic leakage occurred in six patients and the median postoperative stay was 28 days (range 20–42 days). All patients who survived surgery, except one, achieved satisfactory palliation. The nature of these patients is such that whatever is done, mortality will almost inevitably be high. The authors believe that all patients in this series were better off than they would have been if left untreated, and oesophageal bypass should be considered for patients with distressing dysphagia due to disease not amenable to standard palliative methods.     

EVALUATION OF CLOSED-LOOP CONTROL OF ARTERIAL PRESSURE AFTER CARDIOPULMONARY BYPASS

A closed loop computer system has been developed to deliversodium nitroprusside (by infusion) to control systolic arterialpressure (SAP) after cardiopulmonary bypass. The performanceof the closed-loop control system was evaluated by comparingnurse and computer control of SAP in 60 patients during theearly postoperative period. The computer system provided bettercontrol of SAP than manual control by a member of the nursingstaff.     

THE METABOLIC CONSEQUENCES OF JEJUNOILEAL BYPASS FOR OBESITY

Twenty-one female patients studied between six and 12 months following a jejunoileal bypass procedure for obesity were found to have a wide variety of metabolic disturbances. Hepatic histological abnormalities were common and included liver cell necrosis and inflammation in nine patients and hepatic fibrosis in five. Liver function tests were no guide to the degree of hepatic impairment. Vitamin B¹² malabsorption occurred in seven patients, in six probably as a result of bacterial intestinal overgrowth; three of these six patients had the most serious hepatic morphological changes. Malabsorption rather than poor oral Intake of food appeared to account for continued postoperative weight loss in the majority of patients.     

多种移植体修复周围神经的比较实验研究

修复神经缺损的材料甚多，但至今尚未见各种材料的比较研究。为了比较自体神经、肌肉、静脉、肌腱及硅橡胶修复神经缺损的效果，选用ＳＤ大白鼠，切断腓总神经，制成０．６ｃｍ缺损，分别用不同移植物桥接缺损。于术后６周、１２周在电生理、胫前肌称重、远端轴突计数及组织学等方面进行综合分析评价。结果表明：自体神经移植在各方面均优于其它移植体，而静脉组又优于另外３组。对各种移植体中神经再生的特点及其成熟过程进行了讨论，并探讨了形成这种差别的有关神经再生微环境的影响。