Nature and management of duplex abnormalities encountered during infrainguinal vein bypass grafting

PURPOSE

This study was undertaken to evaluate the application of duplex scanning during infrainguinal vein grafting procedures to verify vein conduit preparation, anastomotic patency, and graft hemodynamics.

METHODS

Between 1991 and 1995, 275 infrainguinal vein bypasses (in situ, 114; reversed, 82; nonreversed translocated, 48; spliced alternative/arm vein, 31) to the popliteal (n = 116) or an infrageniculate artery (n = 159) were scanned during surgery for sites of color Doppler flow abnormality. Duplex-detected defects were graded with peak systolic velocity and velocity ratio criteria. Sites that demonstrated highly disturbed flow (peak systolic velocity > 180 cm/sec, velocity ratio > 2.4) were immediately revised by direct repair, patch angioplasty, or interposition grafting.

RESULTS

Intraoperative duplex scanning prompted revision of 50 abnormalities in 43 of the 275 grafts (16%), including 32 vein and seven anastomotic stenoses, nine vein segments with platelet thrombus, and two bypasses with low flow. The intraoperative revision rate was lowest (p < 0.02) for reversed saphenous vein bypasses (7%) compared with other grafting techniques (in situ, 20%; nonreversed translocated, 15%; spliced alternative vein, 23%). The revision rates of popliteal and tibial bypasses were similar (14% vs 17%). A normal result shown by intraoperative scan (235 bypasses) was associated with a low 90-day thrombosis (0.4%) and revision (2%) rate, whereas six of 15 grafts (40%) with residual and 13 of 25 grafts (52%) with unrepaired duplex abnormalities required corrective procedures (p < 0.001). One graft failed within 3 months (secondary patency rate, 99%).

CONCLUSIONS

Intraoperative duplex scanning accurately predicted the technical adequacy of infrainguinal vein grafts and was particularly useful in assessing bypasses constructed with valve lysis techniques or alternative veins. Early graft revisions indicated by duplex monitoring for thrombosis or stenosis were the result of a progression of residual defects and platelet thrombus formation rather than inadequate graft run-off flow.

Failure of foot salvage in patients with end-stage renal disease after surgical revascularization

PURPOSE

This report ascertained factors responsible for for failure of foot salvage in patients with end-stage renal disease (ESRD) after undergoing infrainguinal bypass for critical ischemia.

METHODS

A retrospective review of 69 distal arterial reconstructions performed in 53 patients with ESRD (hemodialysis [n = 37], kidney transplantation [n = 10], peritoneal dialysis [n = 6]) for foot gangrene (n = 28), nonhealing ulcer (n = 25), or ischemic rest pain (n = 16) was conducted. Endpoints of surgical morbidity, limb loss, and graft patency were correlated with extent of preoperative tissue loss and presence of diabetes mellitus.

RESULTS

The 30-day operative mortality rate was 10%, and the patient survival rate at 2 years was 38%. The primary graft patency rate was 96% at 30 days, 72% at 1 year, and 68% at 2 years. Eleven of 22 foot amputations performed during the mean follow-up period of 14 months (range 3 to 96 months) occurred within 2 months of revascularization. Mechanisms responsible for limb loss included graft failure (n = 9), foot ischemia despite a patent bypass (n = 8), and uncontrolled infection (n = 5). Overall, 59% of amputations were performed in limbs with a patent bypass to popliteal or tibial arteries. Healing of forefoot amputations was prolonged, but all limb loss beyond 9 months of revascularization was due to graft failure. The limb salvage rate at 1 year decreased (p = 0.13) from 74% to 51% in patients admitted with gangrene. Only two of seven patients admitted with forefoot gangrene experienced foot salvage.

CONCLUSION

Failure of foot salvage in patients with ESRD and critical ischemia was due to wound healing problems rather than graft thrombosis. Earlier referral for revascularization, before development of extensive tissue ischemia and infection, is recommended. Primary amputation should be considered in patients admitted with forefoot gangrene, particularly if it is complicated by infection.

Antistaphylococcal activity of rifampin-bonded gelatin-impregnated Dacron grafts

The affinity of rifampin to bond to Dacron permits implantation of a vascular prosthesis with anti-staphylococcal bioactivity. The performance of rifampin-bonded Dacron grafts was evaluated in vitro and in vivo to develop a bonding technique with optimal graft bioactivity which was then used for in situ reconstruction of a biofilm graft infection. In vitro bioactivity was measured at 24-hr intervals for three types of Dacron prostheses (plain, gelatin, and collagen-impregnated) exposed to rifampin at varied concentrations and immersion times. Gelatin-impregnated grafts demonstrated superior bioactivity (P < 0.05). Rifampin concentration and graft type had a greater effect on bioactivity than immersion time (P < 0.01). Gelatin-impregnated grafts immersed in a 60 mg/ml rifampin solution for 15 min produced optimum bioactivity. Six grafts prepared in this fashion were used to replace the canine aorta. The level and duration of in vivo antistaphylococcal activity to Staphylococcus aureus and Staphylococcus epidermidis were less (P < 0.05) than those measured in vitro, but rifampin levels exceeded the study strain maximum inhibitory concentration for up to 48 hr. In a canine model, the rifampin-bonded gelatin-impregnated (N = 14) or nonbonded control (N = 10) grafts were used as in situ replacement for an established aortic graft infection caused by S. epidermidis. Replacement with a rifampin-bonded graft resulted in successful anatomic healing of perigraft and anastomotic tissue. Persistent biofilm colonization was confirmed in 8 of 10 controls versus 4 of 14 rifampin-bonded grafts (P < 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

The origin of infrainguinal vein graft stenosis: a prospective study based on duplex surveillance

PURPOSE

The purpose of this study was to determine the origin of vein graft lesions and their propensity for progression based on prospective duplex surveillance of 135 infrainguinal vein bypasses.

METHODS

One hundred sixteen greater saphenous, 13 spliced, five cephalic, and one superficial femoral vein grafts were evaluated by color duplex imaging at surgical procedure, 1 and 6 weeks, 3 and 6 months, and every 3 to 6 months thereafter. Duplex-identified lesions were graded by peak systolic velocity and velocity ratio criteria and were either followed or subjected to revision.

RESULTS

Early postoperative duplex surveillance allowed stratification of infrainguinal grafts into two subsets. Of 91 (67%) grafts with normal early scans (at 3 months), only two (2.2%) developed de novo stenoses (at 6 and 8 months) that required revision. Forty-four grafts with abnormal duplex scans had a focal flow abnormality (peak systolic velocity > 150 cm/sec, velocity ratio > 1.5) in the graft body (n = 24) or anastomotic region (n = 20). In 14 grafts the flow abnormality (mean peak systolic velocity = 217 cm/sec, velocity ratio = 2.3) normalized. Ten additional grafts exhibited a moderate, persistent graft stenosis (mean peak systolic velocity 248 cm/sec, velocity ratio = 3.3) that was not repaired. All 20 grafts with lesions that progressed to high-grade stenosis (mean peak systolic velocity = 362 cm/sec, velocity ratio = 7.2) and were revised had a residual flow abnormality confirmed at operation, or it appeared by 6 weeks. In the entire series six (4.4%) grafts failed during the mean 12-month follow-up interval (range 3 to 30 months), 4 with unrepaired defects and two after revision.

CONCLUSIONS

Prospective duplex surveillance verified that de novo graft stenosis was uncommon (< 2.2%) after reversed and in situ saphenous vein bypass grafting. Graft stenoses developed at sites of unrepaired defects or early appearing conduit abnormalities. An early appearing duplex focal flow abnormality warranted careful surveillance, because one half of such sites progressed to a high-grade stenosis. Grafts with normal early duplex scans exhibited a low incidence of stenosis development or occlusion, and thus less intense postoperative surveillance can be recommended.

Intraoperative duplex scanning of arterial reconstructions: fate of repaired and unrepaired defects

PURPOSE

Because unrecognized lesions can cause an arterial reconstruction to fail, duplex ultrasonography was evaluated as an intraoperative aid to assess technical adequacy and provide criteria for which lesions should be repaired immediately versus safely followed.

METHODS

Since 1990 intraoperative color duplex scanning(7 to 10 MHz linear array probe, pulsed-wave Doppler test spectrum analysis) was used to assess the frequency and severity of residual lesions in 368 patients after carotid endarterectomy (n = 210), infrainguinal vein bypass (n=135) or visceral/renal reconstruction (n = 23). Duplex scan results were categorized as normal or abnormal, with immediate repair of lesions demonstrating both lumen reduction and severe focal flow abnormalities (peak systolic velocity [Vp] > 150 to 180 cm/sec;velocity ratio [Vr] > 2.4). Arteriography was also performed in 81% of lower limb bypass procedures.

RESULTS

Duplex scanning identified technical (residual plaque, stricture) or intrinsic defects (platelet thrombus, distal thrombosis) requiring revision in 37 (10%) of the reconstructions. Infrainguinal bypass had the highest incidence of corrected defects (14%) and adverse events (3%). No adverse events occurred in patients with normal duplex scan results or after carotid endarterectomy. Overall, 76% of identified defects were corrected (carotid, 17 of 24; infrainguinal bypass, 19 of 24; visceral bypass, 1 of 1). Unrepaired flow defects (Vp = 150 to 190 cm/sec; Vr = 1.8 to 2.5) led to one graft occlusion and three early revisions. Postoperative duplex scanning demonstrated residual stenosis in seven of 12 patients with unrepaired defects, two of 36 patients with repaired defects, and five of 312 patients with normal scan results (p < 0.001).

CONCLUSION

Based on the types of lesions corrected and the low (< 0.5%) complication rate after a normal or modified arterial reconstruction, duplex scanning was found to be a valuable intraoperative aid. Unrepaired defects require close surveillance for progression.

Prosthetic graft infection

This article outlines the tenets and basic data critical for the management of prosthetic graft infections. Diagnostic algorithms and treatment options appropriate for patients with symptoms and signs suggestive of graft infection are presented.

The lateral approach to the proximal popliteal artery for popliteal to anterior tibial artery bypass

The exposure of the proximal popliteal artery through a lateral incision for bypasses to the anterior tibial artery is simple and logical. It avoids the need to direct the graft from the medial to the lateral side of the leg and, therefore, is advantageous when limited autogenous vein is available. The lesser saphenous vein is usually long enough to reach the most distal anterior tibial artery.