Vascular endoscopy: useful tool or interesting toy

Intraoperative angioscopy may improve the outcome of in situ saphenous vein bypass grafting: a prospective study

OBJECTIVE

To find out whether intraoperative angioscopic assistance has any effect on graft outcome in patients with critical leg ischemia.

MATERIAL AND METHODS

One hundred one patients requiring a below-knee bypass were assigned to undergo in situ saphenous vein bypass with or without intraoperative angioscopic assistance; otherwise treated similarly including preoperative duplex vein mapping, intraoperative graft flow measurements, and angiography. Data on operative details, morbidity, hospital stay, and graft patency were collected prospectively and compared. All patients were followed up for 12 months.

RESULTS

The group that underwent angioscopy (A) and the control group (B) were similar in all respects, except for the number of patients enrolled in the groups (32 and 69, respectively). Angioscopy revealed incompletely destructed valves in 34 patients (range, 0 to 5; mean 1), undiagnosed vein branches in 111 patients (mean 4.3), and partly occluding thrombus in 5 patients. The number of postoperative arteriovenous fistulas with signs of failing graft and a need for angiographic or surgical reintervention were significantly higher in group B (P <.0001). The 1-year primary patency rate was significantly better in group A (P <.01), but the primary assisted and secondary patency rates did not differ between the groups.

CONCLUSIONS

Angioscopic assistance has an impact on primary graft patency, minimizes the risk for graft failure and thus reduces the need for reintervention by allowing identification of persistent saphenous vein branches, incomplete valve destruction, and partly occluding graft thrombus without adding extra operative time.

Angioscopy for quality control of saphenous vein during bypass grafting

OBJECTIVES

Although autogenous vein is the conduit of choice for infrainguinal bypass grafting, some 20-30% of vein grafts fail during the first year postoperatively. Many of these failed veins are now known to have pre-existing pathological changes. Angioscopy enables intraoperative endoluminal visualisation of veins and can reveal anomalies, some previously unsuspected, despite preoperative Duplex ultrasound mapping and normal external appearances. The aim of this study was to compare angioscopic findings with contemporary histological appearances and with subsequent graft outcome and ultimately, to identify those endoluminal features which might be predictive for failure.

METHODS

Angioscopic vein inspection was carried out using Olympus 1.4 and 2.2mm angioscopes in patients undergoing femoropopliteal/distal bypass. Severe disease in the veins of five patients led to preferential use of polytetrafluoroethylene (PTFE) for above-knee bypasses. The remaining 38 videotaped sequences were reviewed by two surgeons and scored using a scale of 0 to 3, based on frequency and distribution of angioscopically detected lesions. These included haemorrhagic mural plaques, flimsy intraluminal strands, webs/bands and mobile/adherent thrombus. Vein harvested at operation was assessed by a pathologist according to the level of pre-existing abnormality.

RESULTS

There were significant associations between angioscopy/histology scores and graft survival (chi 2 = 22.00; df:3; p < 0.001; chi 2 = 22.43; df:3; p < 0.001 respectively). There was a significant correlation between angioscopy and histology scores (R8 = 0.725; p < 0.001).

CONCLUSIONS

Angioscopy allows immediate identification of the at risk, poor quality vein graft at the time of surgery, without the delays inherent with histological preparation and assessment. Recognition of abnormalities at angioscopy may ultimately improve graft outcome by prospectively eliminating use of poor vein.

Quantitative endoluminal measurements during angioscopy: an innovative technique

AIM

To evaluate angioscopy in this Unit with respect to its application in lower limb vascular reconstructions. By providing magnified, colour images of the luminal surfaces of vein grafts, anastomoses and native arteries, angioscopy allows direct visualisation of imperfections and is sensitive in diagnosing technical problems. However, assessment is qualitative and magnification of the image can distort the operator's impression of true size. Angioscopy would be more versatile if it were possible to quantify the observed images.

METHOD

A new technique has been developed to measure intra-luminal diameter from the angioscopic images. A linear displacement transducer is attached to the angioscope and accurately monitors its axial shift. Signals from the transducer are received by a personal computer equipped with a video frame grabber and analogue digital converter, together with appropriate software. The computer generates calculated dimensions based on geometrical principles, once each angioscope has been appropriately calibrated at the outset.

RESULTS

Laboratory studies examining tubes of known dimensions have confirmed the reproducibility and accuracy of the technique. Simultaneous angioscopic and Duplex ultrasound measurements of the internal diameters of segments of vein suspended in a water bath were then carried out. Using the Duplex results as the 'gold standard', there was a strong correlation between the measurements obtained with the two techniques (Rs = 0.92).

CONCLUSIONS

In the clinical context, this system has the capability to generate accurate endoluminal measurements during angioscopy. This has application for quality control in the selection of veins and inspection of run-off vessels during bypass grafting and in completion studies, following both operative and percutaneous procedures.