Does the in situ technique improve flow characteristics in femoropopliteal bypass?

The aetiology of vein graft stenoses

The aetiology of vein graft stenosis is poorly understood. In a cohort of 88 patients, the mean internal diameter of the vein grafts that developed a stenosis was 3.7 (3.1-4.2) mm compared to 4.7 (4.4-5.0) mm in those that did not (p = 0.006). The mean lowest compliance value in the 11 patients who developed a stenosis was 0.1 (0.07-0.13) % per mmHg compared to 0.21 (0.19-0.23) % per mmHg in the rest (p < 0.001). The presence of vein incompetence, site of tributaries or valves and the degree of endothelial cell loss were not related to the development of vein graft stenoses. The presence of a macrophage infiltrate (p < 0.001), lymphocyte infiltrate (p < 0.025) and subendothelial smooth muscle cells (p < 0.05) were all significantly more common in those grafts that developed a stenosis. Vein quality is an important factor in the development of graft stenoses.

Vein graft factors in the outcome of femorodistal bypass

Various vein factors affect the outcome of femorodistal bypass using vein in the treatment of lower limb ischaemia. In this review, the effect of factors such as vein size, compliance and morphology are discussed.

The value of duplex scanning with venous occlusion in the preoperative prediction of femoro-distal vein bypass graft diameter

The diameter of the long saphenous vein has been shown to affect the outcome of femoro-distal bypass. Many surgeons regard a vein with a diameter of less than 3 mm as being unsuitable. The long saphenous vein was studied in 35 patients undergoing femoro-distal bypass. Diameter measurements of the vein were performed using an ATL duplex scanner at the groin, mid-thigh and knee. Measurements were performed preoperatively both at rest and with a venous occlusion cuff to dilate the vein, and subsequently at 7 days and 2 months after implantation. The mean diameter of the vein at the mid-thigh was 4.1 mm non-dilated, 5.1 mm with occlusion, 5.0 mm 7 days postoperatively and 5.2 mm at 2 months (ANOVA, p less than 0.05). The mean diameter of the vein at the knee was 3.9 mm non-dilated, 4.8 mm with occlusion, 4.8 mm at 7 days and 4.9 mm at 2 months after operation (ANOVA, p less than 0.025). In all five patients whose preoperative resting vein diameter at the knee or mid-thigh was less than 3 mm, preoperative dilatation occurred, such that the diameter became greater than 3 mm. These results suggest that by using a technique of venous occlusion at the time of pre-operative vein mapping, the functional diameter of the vein can be predicted and vein utilisation may be increased.

Infrainguinal bypass surgery: factors determining late graft patency

The results of 373 infrainguinal bypass grafts, in a single centre, between 1980 and 1988 are reviewed. One hundred and thirty in situ vein (ISV), 47 reversed saphenous vein (RSV), 118 polytetrafluoroethylene (PTFE) and 78 human umbilical vein (HUV) grafts were used. The indications for surgery were disabling claudication in 25 per cent of patients and limb salvage in 75 per cent. In 36 per cent of operations the distal anastomosis was above the knee and in 64 per cent it was below the knee. Overall 5-year patency rates and limb salvage rates respectively were, for ISV (41 and 69 per cent), RSV (62 and 90 per cent), PTFE (31 and 67 per cent) and HUV (29 and 59 per cent). There was no significant difference in patency among these grafts at the above-knee level, but significant differences between vein and prosthetic grafts were evident below the knee (P less than 0.001). Using a proportional hazards model the three factors that consistently correlated with late graft patency were graft type (P less than 0.001), site of distal anastomosis (P less than 0.001) and distal run-off (P less than 0.001). Overall, the results suggest that prosthetic grafts are a suitable alternative to autogenous vein when the distal anastomosis is above the knee, but vein should always be used, if available, below the knee joint.

Current techniques for infrainguinal arterial reconstruction

Infrainguinal reconstruction for peripheral vascular occlusive disease comprises an increasingly complex array of interventions which provide unparalleled options for the salvage of threatened limbs. Conventional autogenous saphenous vein bypass remains the most durable revascularization with anticipated graft patency rates approaching 80 percent after five years and excellent long term limb salvage. These excellent results are equally applicable to vein grafts carried to infrapopliteal and even inframalleolar levels, possibly reflecting increased utilization of the in situ method. Although 20 per cent of grafts fail within five years, secondary intervention results in sustained limb salvage in the majority of patients. In the absence of autogenous vein, however, prosthetic material performs poorly such that new interventions consisting of percutaneous transluminal angioplasty, rotary atherectomy devices and laser systems are under aggressive development. Although initial results with these devices are encouraging, long term patency rates remain poor largely due to restenosis. Further progress seems to depend primarily on an increased understanding of the natural healing response of the injured artery.

Intraoperative assessment of in situ saphenous vein bypass grafts by vascular endoscopy

Intraoperative vascular endoscopy was used in 20 femorocrural in situ saphenous vein bypass procedures in order to control valvular incompetence, to localize side branches and to assess the integrity of the distal anastomosis. We used an Olympus Fiberscope (PF-27L) with a diameter of 2.7 mm and a working length of 80 cm, which had fixed illuminating and viewing fibers and a steerable tip, Valvulotomy was performed according to the technique described by R. Leather using a valve-cutter. In 8 out of 20 patients, partly retained valve leaflets were found by intraluminal inspection and could be immediately corrected. The integrity of the distal anastomosis was verified angioscopically in 14 patients. In addition, venous side branches, which had to be ligated, were easily identified under direct vision and localized by transillumination of the endoscopic light through the skin. Vascular endoscopy seems to be a practicable and time saving method to control in situ vein bypass procedures. The steps of the procedure and early results after 20 bypasses for limb salvage are presented.

Evolution of the in situ bypass

The origins of the in situ vein bypass in Montreal, Canada and in London, England, are described. The subsequent evolution of the original techniques in Europe and the United States are followed. The condemnation of the procedure in the United States in 1969 is noted. The persistence of Cartier in Montreal and Hall in Norway and the revival of interest in the procedure by Leather and Karmody in Albany, New York, is recounted. The pathophysiologic basis for the complications of the method are analyzed and the measures by which they are currently remedied are shown. The method's present superiority is reported. The initial rejection and slow acceptance of this method is explained in terms of the special conditions attendant on its introduction and the attitudes of surgeons to new procedures.