Criteria for identification of the "at-risk" infrainguinal bypass graft

Paclitaxel-coated versus plain balloon angioplasty in the treatment of infrainguinal vein bypass stenosis

OBJECTIVE

The aim of this study was to compare the clinical and hemodynamic outcomes of plain vs paclitaxel-coated percutaneous transluminal angioplasty (PTA) in patients with infrainguinal vein bypass stenosis.

METHODS

A single-center retrospective analysis was conducted of consecutive patients treated by infrainguinal bypass PTA. Primary study end points were primary and assisted primary patency. Secondary end points were clinical and hemodynamic improvement, limb salvage, and survival. Society for Vascular Surgery reporting standards were applied.

RESULTS

From April 2008 to November 2014, 83 infrainguinal vein bypasses were treated for graft stenosis by plain (group A, n = 41) or by paclitaxel-coated PTA (group B, n = 42). The groups did not differ significantly in mean age (71.9 years for both groups; P = .99), hypertension (P = 1.0), hyperlipidemia (P = .5), diabetes (P = .6), coronary artery disease (P = 1.0), smoking (P = 1.0), preoperative ankle-brachial index (P = .08), or bypass characteristics (below-knee, P = .82). Technical success rate was 100% for both groups. Mean follow-up was 2.9 years for group A patients and 2.2 years for group B patients (P = .08). No patient was lost to follow-up. Primary patency rates were 88% vs 87% and 73% vs 75% (P = .19) and assisted primary patency rates were 88% vs 90% and 77% vs 84% (P = .76) for group A and B patients at 1 and 2 years, respectively. Repeat target lesion revascularization rates were 22% vs 14% (P = .17). At the last follow-up, there were eight vs seven bypass occlusions (P = .74) for group A and B patients, respectively. In univariate analysis, proximal in-graft stenosis (Cox F, P = .041), bypass failure <6 months after bypass surgery (Cox F, P = .013), more than one bypass stenosis per graft (Cox F, P = .047), and redo bypass procedure (Cox F, P = .0001) were significantly related to assisted primary bypass patency. Immediate hemodynamic and sustained clinical improvement rates were 88% vs 86% and 70% vs 73% for group A and B patients, respectively. There were three vs one major amputations (P = .36) and eight vs seven deaths (P = .78) in group A and B patients, respectively.

CONCLUSIONS

Paclitaxel-coated and plain angioplasty of significant infrainguinal vein bypass stenoses performed equally well in clinical and hemodynamic improvement and in primary and assisted primary bypass patency rates.

Distal bypasses in patients with diabetes and infrapopliteal disease: technical considerations to achieve success

The combination of diabetes and peripheral arterial disease (PAD) is challenging in many ways. The characteristic and complex distal distribution of PAD often encountered in patients with diabetes means that bypass surgery in this context is technically challenging. In addition, many of these patients have a burden of serious comorbidities that must be optimized and managed concurrently. While the authors acknowledge that "achieving success" in distal bypass relies on much more than technical expertise, there are some technical aspects that should be considered when planning surgery on these patients. This article outlines some important issues in the treatment pathway of a patient with diabetes and PAD requiring distal bypass surgery--from selection and optimization of the patient (in the context of a multidisciplinary team) and preoperative workup, to the operative strategy planning, technical tips, and nonoperative adjuncts. These considerations, as well as sound knowledge of the underlying disease process, confounding medical factors and awareness of the difficulty in predicting treatment outcomes, should help maximize the chances of success.

Significance of the Early Postoperative Duplex Result in Infrainguinal Vein Bypass Surveillance

BACKGROUND

Duplex surveillance of infrainguinal vein grafts may not be efficient.

METHODS

Consecutive patients who had received infrainguinal vein grafts were enrolled in a duplex surveillance program. A first scan at 6 weeks after surgery categorized grafts into four groups: (a) low risk grafts, (b) mild flow disturbance, (c) intermediate stenosis and (d) critical stenosis. Disease progression was assessed over time.

RESULTS

Of 364 grafts followed-up for a median of 23 months, 236 (65%) had no flow abnormality at 6-weeks, and had a 40-month cumulative patency rate of 82%. The remaining 128 (35%) grafts had a flow disturbance. Of 29 critical stenoses, 15 were repaired, 11 occluded and three did not change. Of 57 intermediate lesions, 32 progressed to critical, nine occluded, two were repaired and 14 did not change or improved. Of 42 mild lesions, 16 progressed to a higher grade, four occluded and 22 did not change or improved. There was no significant difference in graft patency between grafts with repaired stenoses and those without stenoses, but grafts with untreated critical stenoses were associated with lower patency (p<0.001).

CONCLUSIONS

A duplex scan 6 weeks after operation can predict those patients who require continuing duplex surveillance.

Intra-operative Doppler Flow Measurement do not Predict ‘At-risk’ Status of Infrainguinal Bypass Grafts

AIMS

Patients undergoing infrainguinal arterial reconstruction using vein conduits, frequently undergo intra-operative Doppler flow measurements to determine technical adequacy. The aim of this study was to determine the proportion of vein grafts with normal intra-operative haemodynamic parameters that were subsequently discovered to be 'at risk' on post-operative duplex surveillance scanning.

METHODS

We prospectively collected data on 82, primary infrainguinal vein bypass grafts. Post papaverine graft flow and peripheral resistance were measured using the Scimed Opdop intra-operative Doppler machine. All grafts were determined to be technically adequate on the basis of measured peripheral resistance units (mPRU) being < or =1. At 1 week, a post-operative duplex surveillance scan was performed. At risk status was determined and compared to the intra-operative Doppler flow measurement. Statistical analysis was performed using the Mann-Whitney U-test.

RESULTS

The post-operative duplex scan demonstrated that 53 (65%) of the 82 vein bypass grafts were diagnosed as being 'not at risk'; and 29 (35%) were regarded as at risk. When the groups were compared, there was no significant difference in intra-operative haemodynamic parameters between those not at risk and those at risk (P=0.19, Mann-Whitney U-test). The 1 month primary patency rate was 79% with a secondary patency rate of 100%.

CONCLUSION

Despite normal intra-operative Doppler flow measurements, 35% of vein grafts were regarded as being at risk at the 1 week post-operative duplex surveillance scan. No single value may be universally applicable for identifying at risk grafts intraoperatively. Indeed, graft failure appears to be a multifactorial process.

Is Duplex Surveillance of Value After Leg Vein Bypass Grafting?

Background— The purpose of this study was to assess the benefits of duplex compared with clinical vein graft surveillance in terms of amputation rates, quality of life, and healthcare costs in patients after femoropopliteal and femorocrural vein bypass grafts.

Methods and Results— This was a multicenter, prospective, randomized, controlled trial. A total of 594 patients with a patent vein graft at 30 days after surgery were randomized to either a clinical or duplex follow-up program at 6 weeks, then 3, 6, 9, 12, and 18 months postoperatively. The clinical and duplex surveillance groups had similar amputation rates (7% for each group) and vascular mortality rates (3% versus 4%) over 18 months. More patients in the clinical group had vein graft stenosis at 18 months (19% versus 12%, P =0.04), but primary patency, primary assisted patency, and secondary patency rates, respectively, were similar in the clinical group (69%, 76%, and 80%) and the duplex group (67%, 76%, and 79%). There were no apparent differences in health-related quality of life, but the average health service costs incurred by the duplex surveillance program were greater by £495 (95% CI £183 to £807) per patient.

Conclusions— Intensive surveillance with duplex scanning did not show any additional benefit in terms of limb salvage rates for patients undergoing vein bypass graft operations, but it did incur additional costs.

Repeat surgery without preoperative angiography in limbs with patent infrainguinal bypass grafts

The aim of this study was to assess the feasibility and results of repeat surgery without preoperative angiography in limbs with patent infrainguinal bypass grafts. Between January 1995 and December 1999, 73 surgical interventions were performed for correction of inflow, graft, or runoff-related lesions in limbs with patent infrainguinal bypass grafts. Fifty-six of the 73 cases were operated on based on the findings obtained from duplex scanning alone. There were 53 vein and 3 prosthetic grafts in the series. The indications for intervention without angiography were stenotic or occlusive lesions in 35, graft aneurysm in 7, and arteriovenous fistulae in 14. There were no deviations from the preoperatively planned surgical strategy in patients undergoing surgery without preoperative angiography. Cumulative life table primary, (stenosis free) and primary-assisted patency rates, at 12 months following graft revisions (excluding arteriovenous fistulae ligatures) without preoperative angiography, were 64% and 85%, respectively. The corresponding figures for revisions performed with preoperative angiography were 58% and 84%, respectively. There were no significant differences between patients undergoing surgery with or without preoperative diagnostic angiography with regard to patency rates. Surgical interventions for correction of infrainguinal graft-related stenotic or aneurysmal lesions can be safely performed based on findings obtained from duplex scanning.

Timing of Doppler ankle brachial pressure index

Are there any guidelines or research evidence to support when it is appropriate to perform a Doppler ankle brachial pressure index (ABPI) after a client has had arterial bypass surgery on their leg? Some vascular surgeons say never, some say six months. As these clients often have reperfusion oedema, it is useful to know ABPI to assist the choice of compression.

Identification of factors predictive of lower extremity vein graft thrombosis

OBJECTIVE

The objective of this study was to assess the prognostic value of hemodynamic parameters measured with duplex ultrasound scan, together with other important graft and patient characteristics, in predicting lower extremity vein graft thrombosis.

METHODS

A total of 165 lower extremity vein grafts were entered prospectively into a postoperative duplex ultrasound scan surveillance program with examinations performed at 1, 2, 3, 4, 6, 9, 12, 18, and 24 months, and annually thereafter. Duplex scan-derived blood flow velocity measurements were recorded at 1562 patient visits over 7 years. Graft patency was determined after each visit, and an analysis of factors predictive of vein graft thrombosis was performed with Poisson regression.

RESULTS

Thirty-two episodes of first-time graft thrombosis occurred, 23 of which were permanent. One-, 3-, and 5-year secondary graft patency rates were 90%, 86%, and 79%, respectively. In multivariate analyses, duplex scan velocity measurements predictive of lower extremity graft thrombosis included the maximum velocity ratio (Vr) in association with a graft stenosis and the mean graft peak systolic velocity (MGV) within nonstenotic portions of the body of the graft. The incidence of graft thrombosis among grafts without inflow/outflow stenoses, with Vr less than 3.5, and with MGV 50 cm/s or more, was 2.9% per year. Incidence rates were considerably higher among grafts with a of Vr of 3.5 or more (incidence rate ratio = 7.0; 95% CI, 3.4-14.6) or an MGV less than 50 cm/s (incidence rate ratio = 6.5; 95% CI, 3.3-13.1). In grafts without identifiable inflow, outflow, or graft stenoses, there was no association between MGV and the risk of graft thrombosis.

CONCLUSION

Duplex scan velocity measurements are valid predictors of impending graft thrombosis. A Vr of 3.5 or more and an MGV less than 50 cm/s are the best predictive measures. Repair of correctable graft lesions with a Vr of 3.5 or more, or inflow, outflow, or graft lesions associated with an MGV less than 50 cm/s are recommended. Grafts without detectable inflow, outflow, or graft stenoses, regardless of MGV, may be safely followed.

Interobserver agreement in duplex scanning for vein grafts

BACKGROUND

although the precision of duplex scanning is of utmost importance in vein-graft surveillance, it has not been properly assessed. This study aims to analyse interobserver agreement on duplex scanning.

METHODS

a blinded comparative trial of 69 infrainguinal vein bypass reconstructions. Two consecutive duplex scans were performed by different examiners and duplex ultrasound machines on the same patient. The duplex examinations were also compared with angiography, when available, and clinical follow-up.

RESULTS

interobserver agreement in Kappa statistics was 0.69, signifying "good" agreement between the examinations in detecting haemodynamically significant changes in the grafts. The sensitivity, specificity and accuracy figures compared with a combination of angiography and follow-up data for the two scans were 80%, 91%, 88% and 85%, 93%, 91%, respectively. The limits of agreement were, however, wide for Doppler-derived velocity characteristics.

CONCLUSION

duplex scanning is an accurate and reproducible method for detecting haemodynamically significant changes in infrainguinal vein grafts.

The importance of revision of early restenosis after endovascular remote endarterectomy in SFA occlusive disease

OBJECTIVES

to investigate the results of revision of recurrent stenoses after superficial femoral artery (SFA) remote endarterectomy.

DESIGN

prospective, non-open, study.

MATERIALS

eighty-eight consecutive patients with long segmental SFA occlusive disease underwent 101 remote end-arterectomy procedures. All patients had chronic lower extremity ischaemia necessitating surgical intervention.

METHODS

clinical, haemodynamic, and duplex examinations were performed postoperatively at regular intervals, identifying 46 recurrent stenosed (PSV ratio >2.5) limbs, which formed the cohort for this study. The median follow-up was 25 months. Secondary revision was performed in 23 limbs, based on recurrent symptoms and individual preference of the attending vascular surgeon. Cumulative primary and primary assisted-patency rates were compared using the log-rank test of significance.

RESULTS

univariate analysis did not show any significant differences for other demographic and lesion characteristics apart from recurrent symptoms (all revised). Multivariate analysis revealed that revision "adjusted for time-of-onset" predicted reocclusion (p=0.007; HR 0. 21; 95% CI 0.06, 0.66). Among subjects in whom restenoses developed within 1 year, revision of recurrent stenoses improved primary patency rates from 47% to 77% at 30 months.

CONCLUSIONS

revision of early (<1 year) recurrent stenoses improves the mid-term patency rates of SFA remote endarterectomy.

Surveillance of above-knee prosthetic femoropopliteal bypass

OBJECTIVES

To evaluate a surveillance programme based on colour duplex ultrasound scanning of above-knee prosthetic femoropopliteal bypass.

DESIGN

A retrospective clinical study.

MATERIALS

One hundred and eighteen above-knee prosthetic femoropopliteal bypass procedures performed from 1993 to 1996.

METHODS

Scans were done at 1, 3, 6 and 12 months, and annually thereafter. Significant graft-related stenotic lesions were defined as 50% diameter reduction or more located at the inflow or outflow arteries, or associated with the graft. Identified lesions were treated by angioplasty or surgical repair.

RESULTS

The primary and secondary patency rates at 2 years were 55% and 71%, respectively. Stenotic lesions were documented on 45 of 463 scans (9.7%). Twenty-nine grafts (25%) were treated and only six of these grafts (21%) occluded. This was significantly superior to the occlusion rate of 41% for the whole series.

CONCLUSIONS

It appears that one-quarter of above-knee prosthetic femoropopliteal bypasses develop graft-related stenoses. The favourable prognosis of these grafts after treatment for stenotic lesions justifies a surveillance programme. However, most graft occlusions seem to occur in grafts where no stenotic lesion has been previously detected.

The utility of duplex scanning in infrainguinal vein graft surveillance: results from a randomised controlled study

OBJECTIVES

To evaluate the utility and efficacy of colour-coded duplex scanning as an adjunct to clinical surveillance of infrainguinal vein bypass surgery.

DESIGN

Prospective controlled randomised trial.

METHODS

The trial included 179 consecutive patients undergoing 185 primary infrainguinal vein graft reconstructions during a 3-year period. Patients alive without amputation and with open graft at 1 month were randomised to a surveillance program based on clinical examination and ankle-brachial pressure index measurement (ABI group) or additional duplex scanning (DD group). All patients were scheduled for surveillance at 1, 3, 6, 9 and 12 months after operation.

RESULTS

Surveillance identified four failing grafts in the ABI group and 11 in the DD group which were revised. The number of occluded grafts was seven in ABI group and 12 in DD group. At 1-year overall cumulative assisted primary patency rates in the ABI group and in the DD group were 74% and 65% respectively (p = 0.21), corresponding secondary patency rates were 84% and 71% (p = 0.04) and limb salvage rates 88% versus 81% (p = 0.23) respectively.

CONCLUSIONS

This study failed to show any beneficial effect of duplex scanning in a surveillance program, which was difficult to accomplish as a part of routine clinical work. However, the main difference in outcome appeared during the first postoperative month before the commencement of the surveillance program.

At what peak velocity ratio value should duplex-detected infrainguinal vein graft stenoses be revised?

OBJECTIVES

To determine the peak velocity ratio (PVR) threshold at which to intervene and correct duplex detected vein graft stenoses.

DESIGN

Prospective study.

MATERIALS

Infrainguinal vein grafts in patients attending the vascular studies for routine postoperative surveillance.

METHODS

Colour duplex detected stenotic vein graft lesions with a peak velocity ratio (PVR) between 2.0 and 2.9 were identified and monitored by serial duplex scans performed monthly for 3 months and then at 3-monthly intervals thereafter. At the end of the study period, the outcome of these lesions were analysed.

RESULTS

Thirty-eight lesions were identified from 32 grafts. Of these lesions, sixteen (42%) resolved, 11 (29%) remained stable and 11 (29%) progressed to a PVR of > or = 3.0 and underwent angioplasty. There were no occlusions in any of the grafts during the period of study.

CONCLUSIONS

Colour duplex detected vein graft stenoses with a PVR of less than 3.0 can be treated expectantly if grafts with stenoses with a PVR 2.0-2.9 are scanned every month for at least 3 months after detection.

Vein graft surveillance: is graft revision without angiography justified and what criteria should be used?

PURPOSE

The objective of this study was to assess the accuracy of color-flow duplex surveillance parameters to detect infrainguinal vein graft stenoses and to investigate whether graft revision without angiography is justified.

METHODS

In a prospective study in which three centers participated, the data of graft surveillance in 300 patients were analyzed. For the evaluation of surveillance criteria all patients underwent a digital subtraction angiography if a graft stenosis was suspected. To create a control group, in patients with normal grafts a consented digital subtraction angiography was performed also. From these data the accuracy of seven duplex and three ankle blood pressure-derived variables was assessed. The relation between various surveillance criteria and continued graft patency was determined with life table analysis with the transient state method.

RESULTS

The mean follow-up period was 20 months (range, 1 to 40 months). At univariate and multivariate analysis the peak systolic velocity (PSV) ratio provided the best correlation with angiographic stenoses > or = 70% (PSV ratio cutoff 3.0: sensitivity 80%, specificity 84%). This finding did not differ between the participating centers. With life table methods it was demonstrated that the best combination of efficacy (limitation of the number of unnecessary revisions), safety (minimal number of correctable lesions missed), and reduction of angiograms was obtained by a two-parameter surveillance algorithm. This algorithm included a PSV ratio < 2.5 to delineate patients in whom a conservative approach without angiography or revision was appropriate, a PSV ratio > or = 4.0 to indicate patients in whom vein graft revision without angiography could be scheduled, and a group with PSV ratios between 2.5 and 4.0 in whom angiography was to be performed to determine clinical management on the basis of the stenosis severity. This algorithm had a positive predictive value of 93% and a negative predictive value of 89%. In addition, it resulted in a reduction of the number of angiograms of 49% compared with a policy of angiographies in all patients with a PSV ratio > or = 2.5.

CONCLUSIONS

The best criterion to identify a failing graft is the PSV ratio. With a two-parameter algorithm for vein graft surveillance, the incidence of unnecessary revisions and of missed high-grade lesions was acceptably low, whereas the number of angiograms was reduced by one half.

Have the results of infrainguinal bypass improved with the widespread utilisation of postoperative surveillance?

OBJECTIVES

The objectives of this study were to assess the impact of Duplex surveillance on the results of infrainguinal vein grafts. A review has been performed comparing the outcome of vein grafts undergoing Duplex surveillance plus prophylactic treatment of stenoses to that of vein grafts followed clinically.

DESIGN, PATIENTS, AND METHODS

Only studies providing information on occlusion rates were included. Mortality and limb salvage rates were also analysed but were not available from all studies.

RESULTS

2680 surveillance and 3969 non-surveillance vein grafts were analysed. There was no significant difference between the two groups with respect to presence of critical ischaemia (p=0.3) and level of distal anastomosis (p>0.5). Surveillance identified 493 stenoses in 469 (19%) grafts, 397 (16%) grafts were treated by surgery (248; 62%) and angioplasty (149; 38%). Ninety-eight (26%) grafts developed recurrent stenoses. Total number of deaths, total number of occluded grafts and number of occlusions after 30 days were significantly greater for the non-surveillance group (p<0.001; p<0.001; p<0.01). Perioperative occlusion rates were not significantly different (p=0.1). Few surveillance studies reported limb salvage rates (6 of 17). The numbers of amputations were not significantly different between the two groups (p>0.5).

CONCLUSIONS

The patency of infrainguinal vein grafts would appear to be improved as a result of surveillance. However, no improvement in limb salvage has been demonstrated.

Vein graft stenosis: incidence and intervention

OBJECTIVES

The incidence of vein graft stenosis ranges from 5%-45%. Reported rates appear to be increasing as technological advances make detection easier. The aim of this study was to review our experiences with regard to the incidence of stenosis in infrainguinal bypass grafts and the outcome of intervention for salvage of failing grafts.

DESIGN

Retrospective review of graft surveillance records.

SETTING

Vascular Studies Unit, Bristol Royal Infirmary.

METHODS

A Duplex-based graft surveillance (GS) programme was used from January 1989 to June 1994 to study 275 primary graft procedures in 250 patients with lower limb ischaemia. Patients were scanned at 1 week, 6 weeks and 3, 6, 9 and 12 months postoperatively.

RESULTS

One year cumulative limb salvage, patient survival and primary, primary assisted and secondary patencies were 91%, 83%, 67%, 77% and 84% respectively. Duplex scanning detected 85 vein graft stenoses in 59 patients: an incidence of 21.5%. In addition, 64 potentially graft-threatening inflow (14) and outflow (50) problems were detected in the native vessels of 52 patients from clamp damage or progression of disease (POD). Of the 85 graft stenoses, 40 were treated by balloon angioplasty (PTA) and 20 by surgical intervention and 1 patient's symptoms were treated by chemical sympathectomy. Twenty-four patients were not actively treated. Of the 64 grafts affected by POD, 20 were treated by PTA, 15 by surgery, one with anti-coagulation and 28 had no treatment. Comparing patients with non-treated and treated lesions, the respective 12 month cumulative patencies for patients with graft stenoses were 75% and 87.5% as against 86% and 83% for patients with POD (log rank test 0.1).

CONCLUSIONS

These results uphold the perceived benefits of a GS programme, although the evidence from the non-treated cases in this series reinforces a need for a large, prospective, randomised trial to confirm the case for GS.

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.

Late reoperation in vascular surgery

OBJECTIVES

Assessment of late reoperation (after 30 days) following vascular surgery.

DESIGN

Analysis of a prospectively collected database of consecutive patients undergoing vascular surgery.

SETTING

A single teaching unit's experience between 1986-1993.

MATERIALS

Patients undergoing 2501 primary arterial reconstructions.

CHIEF OUTCOME MEASURES

Reoperation after 30 days.

MAIN RESULTS

One hundred and fifty eight patients (6%) underwent further operations, at more than 1 month after the primary procedure. Primary procedures at highest risk for reoperations were axillobifemoral bypasses and femorodistal bypasses with respective late reoperation rates of 20% and 16%. The majority of patients required late reoperation because of graft occlusion or stenosis. Overall, of the 158 late reoperations performed, 114 were related to the same arterial segment with the same presenting symptoms as the primary operation, and 44 for a different indication. A second or subsequent reoperation was required in 54 patients and the overall operative mortality was 11%.

CONCLUSION

Patients undergoing certain vascular procedures, should be informed of the high risk of a subsequent procedure when consent is obtained.

Simple hyperaemia test as a screening method in the postoperative surveillance of infrainguinal in situ vein bypasses

OBJECTIVES

To develop a simple protocol for ultrasound Duplex surveillance of infrainguinal vein bypasses.

DESIGN

The value of three Doppler waveform parameters, obtained from a single point of the bypass, for identification of stenoses was studied in 91 in situ vein bypasses. Midgraft peak systolic velocity (PSV), pulsatility index (PI) and ratio of hyperaemic and resting time-average mean velocities (TAMV), (TAMV ratio = TAMVhyperaemia/TAMVrest) were correlated with the presence and severity of stenoses as assessed by conventional Duplex scanning and ankle-brachial index (ABI) measurements. The optimal value of the waveform parameters for discrimination between bypasses with and without evidence of stenoses was determined by receiver operating characteristics (ROC) analysis.

MAIN RESULTS

Complete Duplex scanning of the entire graft revealed an increase in the peak systolic velocity by a factor 2.5 indicative of significant stenoses in 24 (26%) patients. A PSV below 55 cm/s was a poor indicator of stenoses (sensitivity 46%, specificity 76%) and PI < or = 3.8 only allowed suboptimal discrimination between normal and stenotic bypasses (sensitivity 63%, specificity 75%). The hyperaemic response assessed by TAMV ratio proved the best parameter for identification of graft stenoses. A TAMV ratio of 2.0 or less correctly identified 21 of the 24 lesions (sensitivity 88%, specificity 75%) and none of the three bypasses with evidence of stenoses and TAMV ratios exceeding 2.0 failed during follow-up.

CONCLUSIONS

Single point waveform analysis of vein bypass velocity profile at rest and during reactive hyperaemia is a simple screening method providing diagnostic and prognostic information which may be of value in the postoperative surveillance of infrainguinal vein bypasses.

The value of pre-discharge Duplex scanning in infrainguinal graft surveillance

OBJECTIVES

Protocols and criteria for Duplex-based graft surveillance programmes (GS) vary widely as to the optimum regimens for maximising detection of "at risk" grafts. Few centres recommend starting GS before discharge. The aim of this study was to audit our experience with respect to early scanning.

SETTING

Vascular Studies Unit, Bristol Royal Infirmary.

METHOD

The records of 123 patients entering GS from January 1992 were reviewed. Patients were scanned at 1 week, 6 weeks and 3, 6, 9 and 12 months post-bypass. Haemodynamic criteria used were a peak mean velocity (PMV) less than 45 cm/s and a focal velocity disturbance with a V2/V1 ratio of 1.5 or more.

RESULTS

Forty-six abnormalities (37% detection rate) were identified on scans within one week. In all cases, on-table completion studies with either arteriography and/or flow measurements had failed to identify the anomalies subsequently detected by Duplex. At 1 week, six grafts had occluded, 27 had a focal PMV increase (mean V2/V1 ratio: 2.6; range 1.5-4.3), four had low flow velocities, four had arteriovenous fistulae, one contained mobile thrombus, two had retained cusps and two had hamstring entrapment. Of 40 patent, but compromised grafts, 18 warranted immediate investigation. Of the 27 patients with velocity disturbances on Duplex, 25 were simply observed but, eight have since required intervention for definitive stenoses at these sites which, in retrospect, were evident within the first postoperative week.

CONCLUSIONS

Pre-discharge scanning is a useful modality for detecting technical problems. Intrinsic graft abnormalities, possibly the sites of future definitive stenoses, have been visualised even at 1 week and once identified, can be more closely scrutinised thereafter. Pre-discharge colour Duplex is recommended as standard practice for quality control after infrainguinal bypass.