Early remodeling of lower extremity vein grafts: inflammation influences biomechanical adaptation

BACKGROUND: The remodeling of vein bypass grafts after arterialization is incompletely understood. We have previously shown that significant outward lumen remodeling occurs during the first month of implantation, but the magnitude of this response is highly variable. We sought to examine the hypothesis that systemic inflammation influences this early remodeling response. METHODS: A prospective observational study was done of 75 patients undergoing lower extremity bypass using autogenous vein. Graft remodeling was assessed using a combination of ultrasound imaging and two-dimensional high-resolution magnetic resonance imaging. RESULTS: The vein graft lumen diameter change from 0 to 1 month (22.7% median increase) was positively correlated with initial shear stress (P = .016), but this shear-dependent response was disrupted in subjects with an elevated baseline high-sensitivity C-reactive protein (hsCRP) level of >5 mg/L. Despite similar vein diameter and shear stress at implantation, grafts in the elevated hsCRP group demonstrated less positive remodeling from 0 to 1 month (13.5% vs 40.9%, P = .0072). By regression analysis, the natural logarithm of hsCRP was inversely correlated with 0- to 1-month lumen diameter change (P = .018). Statin therapy (beta = 23.1, P = .037), hsCRP (beta = -29.7, P = .006), and initial shear stress (beta = .85, P = .003) were independently correlated with early vein graft remodeling. In contrast, wall thickness at 1 month was not different between hsCRP risk groups. Grafts in the high hsCRP group tended to be stiffer at 1 month, as reflected by a higher calculated elastic modulus (E = 50.4 vs 25.1 Mdynes/cm2, P = .07). CONCLUSIONS: Early positive remodeling of vein grafts is a shear-dependent response that is modulated by systemic inflammation. These data suggest that baseline inflammation influences vein graft healing, and therefore, inflammation may be a relevant therapeutic target to improve early vein graft adaptation.     

Early biomechanical changes in lower extremity vein grafts--distinct temporal phases of remodeling and wall stiffness

BACKGROUND: The geometric and biomechanical changes that contribute to vein graft remodeling are not well established. We sought to measure patterns of adaptation in lower extremity vein grafts and assess their correlation with clinical outcomes. METHODS: We conducted a prospective, longitudinal study of patients undergoing infrainguinal reconstruction with autogenous conduit. In addition to standard duplex surveillance, lumen diameter (of a defined index segment of the conduit) and pulse wave velocity (PWV) were assessed by ultrasound imaging at surgery and at 1, 3, and 6 months postoperatively. Graft dimensions and wall stiffness were correlated with clinical outcomes. RESULTS: There were 92 patients and 96 limbs in this study. On average, vein graft lumen diameter increased during the first month of implantation from 0.37 +/- .01 cm to 0.45 +/- 0.02 cm (mean +/- SEM; P = .002), representing a relative change of +21.6% (median +/- 14%; range, -31 to +67%) during this period. Of the entire cohort, 72% of grafts demonstrated appreciable dilation of the index segment during the first month. Index segment lumen diameter did not change appreciably beyond 1 month, with the notable exception of arm vein conduits, which showed continued tendency to dilate. PWV increased during the first 6 months (17.2 +/- 1.2 m/s to 23.2 +/- 2.4 m/s; P = .008), reflecting a nearly 40% increase in conduit stiffness (2.0 +/- .6 Mdynes/cm to 3.3 +/- .8 Mdynes/cm, P = .01). The greatest relative increase (25%) in PWV occurred from months 1 to 3. Loss of primary patency occurred in 24 cases (19 revisions, 5 occlusions), with a mean reintervention time of 7.6 months. Grafts that demonstrated early positive remodeling (lumen dilatation) had a trend of increased primary patency (P = .08, log rank). Among the grafts that failed, a trend was noted toward greater wall stiffness at 1 month, 2.7 vs 1.5 Mdynes (P = .08). CONCLUSION: Vein graft remodeling appears to involve at least two distinct temporal phases. Outward remodeling of the lumen occurs early, and wall stiffness changes occur in a more delayed fashion. Early outward remodeling may be important for successful vein graft adaptation.     

Cephalic vein grafts for lower extremity revascularization.

From 1980 to 1989 infrainguinal revascularization was performed with cephalic vein grafts in a consecutive series of 34 patients (35 limbs) whose saphenous veins were either inadequate or already had been harvested for previous coronary (N = 16, 47%) or ipsilateral lower extremity bypass (N = 19, 56%). Surgical indications included ischemic rest pain or focal tissue necrosis in 25 limbs (71%), disabling claudication in six (17%), and popliteal aneurysms or prosthetic femoropopliteal graft infections each in two (6%). Preliminary arteriovenous fistulas were constructed in the arms of 23 patients (68%) to enhance the diameter of their cephalic veins, and 24 (69%) of the 35 infrainguinal procedures in this series were performed with use of cephalic vein alone. The distal popliteal artery was used for the outflow anastomosis in 10 limbs (29%), a tibial vessel was used in 12 (34%), and the peroneal artery was used in 13 (37%). Fourteen graft occlusions (40%) and six amputations (17%) have occurred during follow-up intervals of 1 to 107 months (mean, 28 months; median, 27 months). At 3 years the cumulative primary patency rate is 40%, the secondary patency rate is 46%, and the limb salvage rate is 82%. Despite their relative inconvenience, cephalic vein grafts appear to be preferable to prosthetic materials for infrainguinal revascularization below the knee.     

Patency and characteristics of lower extremity vein grafts requiring multiple revisions

OBJECTIVES: Multiple (> 1) revisions of lower extremity vein grafts may be required to maintain patency. Characteristics of recurrent lower extremity vein graft lesions and the patency achieved after multiple revisions have not been emphasized in reports on infrainguinal vein graft stenosis. This study was performed to determine (1) the patency of multiply revised lower extremity vein grafts and (2) the timing, location, and angiographic and duplex features of the recurrent lesions. METHODS: Lower extremity vein grafts that were followed in a duplex surveillance protocol and required revisions from January 1990 through December 1998 were identified. All revisions were preceded by angiography. In multiply revised lower extremity vein grafts, the immediate preoperative angiogram and duplex examination findings, as well as the angiogram made before the previous revision and the duplex study done after the previous revision, were reviewed to characterize recurrent lesions at the time of previous and current graft revision. The patencies of grafts undergoing single and multiple revisions were compared. RESULTS: A total of 233 lower extremity vein graft revisions were performed; of these, 50 (21%) were repeat revisions. Of grafts requiring more than one revision, 98% were normal on duplex examination after the initial revision. Five-year assisted primary patency of multiply revised grafts (91%) was not different from that of grafts with a single revision (89%; P not significant). Of 60 lesions repaired in the 50 repeat revisions, 29 (48%) were at the previously revised site, and 31 (52%) were at new sites. The time between revisions was less if the same site was revised (11 +/- 2 months) than if a different site required revision (20 +/- 4 months; P <.05). Arteriographic evidence of a minor (< 50% diameter) lesion was present at the time of the initial revision in 23% of cases in which revision of a second site was subsequently required. CONCLUSION: In our experience, 21% of lower extremity vein grafts requiring initial revision ultimately require additional revisions. Multiply revised lower extremity vein grafts have excellent long-term patency. Lesions occur with equal frequency at the site of prior revision and new sites. Lesions prompting revision at new sites occur significantly later and are infrequently detected on prior imaging studies.     

Comparison of expanded PTFE and vein grafts in lower extremity arterial reconstructions

Polytetrafluoroethylene (PTFE) bypasses were used in a series of arterial reconstructions to the popliteal artery (45) and to arteries below that level (11). These were performed in high-risk situations in patients who lacked a suitable saphenous vein. Vein bypasses were performed in a comparable series of high-risk situations in patients having a suitable autologous saphenous vein (45 to the level of the popliteal artery and 11 to an artery below that level). PTFE patency rates at 4-14 months were 43 to 45 (96%) for the femoro-popliteal reconstructions (with a limb salvage rate of 39 to 45 or 87%) and 5 of 11 (45%) for the distal bypasses. Saphenous vein bypass patency rates at 8-14 months were 39 of 45 (87%) for the femoropopliteal reconstructions (with a limb salvage rate of 36 of 45 or 80%) and 5 of 11 (45%) for the distal bypasses. These results justify continued use of PTFE grafts in patients without saphenous veins who require lower extremity arterial reconstructions for limb salvage. The exact place of PTFE grafts in arterial reconstructive surgery of the lower extremity definition based on longer periods of observation.     

Reliability of primary vein grafts in lower extremity free tissue transfers.

Free flaps transferred to the lower extremity have a higher risk of failure, which may be expected to increase further with the use of vein grafts. The results of 103 consecutive free flaps to the lower extremities of 98 patients who were operated from March 1994 to December 1999 were evaluated to assess the reliability of vein grafts in lower extremity reconstruction. Five flaps were lost and the overall success rate was 95.1%. Eighty-four free tissue transfers in 79 patients were performed for the reconstruction of traumatic cases, and 81 of these flaps were performed in a delayed manner, between 1 week and 4 months after the injury. Interpositional vein grafts were used primarily in 22 flaps--all in traumatic cases--and 21 of them survived completely (95.4%). Primary vein grafts were used both for arteries and veins in 15 flaps and for arteries only in 7 flaps. The most common cause of tissue loss in these patients was a crush injury in earthquake survivors, followed by electrical injuries, gunshot injuries, motor vehicle accidents, and chronic infections. Free muscle flaps in 13 patients, skin flaps in 4 patients, osseous flaps in 2 patients, and temporal fascial flaps in 2 patients were the flaps of choice in vein graft reconstructions. Although a higher incidence of flap loss has been reported with the use of interpositional vein grafts than with regular transfers, and the technical and pathophysiological problems in flap transfers are also high in the lower extremity, the success rate in vein-grafted free flaps did not differ from that of the simple free flap transfers in the current series. This appears to be the result of meticulous preoperative planning and proper selection of recipient vessels during optimal operative conditions.     

Treatment of failed lower extremity bypass grafts with new autogenous vein bypass grafting

During the last 9 years we performed 111 bypass procedures for lower extremity ischemia, which occurred after failed infrainguinal bypass grafting. An all autogenous reversed vein bypass was achieved in 103 of 111 operations (93%). Five-year primary and secondary patency of bypasses placed as treatment for one or more failed prior bypass(es) was 57% and 71%, respectively, as compared to 80% and 83%, respectively, for 5-year primary and secondary patency of simultaneously placed first time leg bypasses. Five-year limb salvage for bypass procedures performed as treatment for failed bypass was 90%, which was identical to that achieved for first time bypasses.     

Management of infected lower extremity autologous vein grafts by selective graft preservation.

Between 1975 and 1991, we treated 16 patients with infected lower extremity autologous vein grafts performed for limb salvage by complete graft preservation. Traditional treatment of these infections includes immediate graft excision and complex revascularization procedures to prevent limb loss. The infection involved an intact anastomosis in 12 patients or the body of a patent graft in 4 patients. None of the patients was systemically septic. All patients were treated with appropriate intravenous antibiotics. Six patients were treated by placement of autologous tissue on the exposed graft (4 rotational muscle flaps, 2 skin grafts), and 10 were treated with antibiotic-soaked dressing changes and repeated operative débridements to achieve delayed secondary wound healing. This treatment resulted in a 19% (3 of 16) mortality rate and an 8% (1 of 13) amputation rate in survivors. Of the six patients managed by autologous tissue placement onto the infected graft, five patients had wounds that healed without complications, and one died of a myocardial infarction. Of the 10 patients treated by delayed secondary wound healing, 2 developed anastomotic hemorrhage, which resulted in death in 1 patient and above-knee amputation in the other, 1 died of a myocardial infarction, 1 developed graft thrombosis, and 6 had wounds that healed. Placement of autologous tissue to cover an exposed, infected patent vein graft with intact anastomoses may prevent graft dessication, disruption, and thrombosis, which renders graft preservation an easier, safer method of treatment compared with routine graft excision.     

Factors affecting symptomatic vs asymptomatic vein graft stenoses in lower extremity bypass grafts

OBJECTIVE: To determine differences in patients undergoing lower extremity vein graft revisions presenting with and without recurrence of preoperative symptoms. DESIGN: Retrospective case-control study of a prospectively maintained database. SETTING: University and veterans' administration hospitals PATIENTS: Two hundred nineteen lower extremity vein graft revisions were performed in 161 patients from January 1995 to January 2007. Patients were categorized as asymptomatic or symptomatic (recurrence of initial symptoms) at the time of revision. MAIN OUTCOME MEASURES: Univariate analysis was performed to assess differences in patient demographics, details of initial operation, site of recurrent lesion, and follow-up surveillance data between symptomatic and asymptomatic patients. Independent predictors of symptomatic recurrence were identified with multivariate logistic regression. Primary assisted patency was compared between revisions performed for symptomatic and asymptomatic lesions. RESULTS: Vein graft stenoses were asymptomatic in 125 cases (57%) and symptomatic in 94 cases (43%). Symptomatic recurrences were associated with a significantly greater drop in ankle brachial index than asymptomatic lesions (mean [SD], 0.21 [0.03] vs 0.11 [0.02]; P = .003). Distal graft or outflow lesions were significantly associated with symptom recurrence (P = .048). Multivariate analysis identified ankle brachial index decrease (odds ratio, 6.803; 95% confidence interval, 1.418-32.258; P = .02) and the use of alternate graft conduit (odds ratio, 2.633, 95% confidence interval, 1.243-5.578; P = .01) as independent predictors of recurrent symptoms. Overall 5-year patency was the same regardless of preoperative symptoms (82% symptomatic and 88% asymptomatic; P = .30). CONCLUSIONS: Symptomatic recurrences are associated with larger decreases in ankle brachial index, distal lesions, and alternate conduit grafts. Duplex surveillance is necessary to identify asymptomatic vein graft stenoses. Because graft patency is independent of preoperative symptoms, surveillance consisting of clinical follow-up with ankle brachial index evaluation warrants further consideration.     

Arm vein conduit is superior to composite prosthetic-autogenous grafts in lower extremity revascularization

PURPOSE: Various alternative conduits have been used for lower extremity revascularization when an adequate ipsilateral greater saphenous vein is absent. This study compared the effectiveness of all-autogenous multisegment arm vein bypass grafts with that of composite grafts composed of combined prosthetic and autogenous conduits. METHODS: One hundred fifty-three lower extremity revascularization procedures performed between 1990 and 1998 were followed up prospectively using a computerized vascular registry. The grafts were composed of spliced arm vein segments with venovenostomy in 122 and of composite prosthetic-autogenous conduit in 31. Arm vein conduit was prepared by means of intraoperative angioscopy for valve lysis and identification of luminal abnormalities in 47.7% of cases. RESULTS: Bypass graft configurations were as follows: femoropopliteal (12 arm vein, 2 composite); femorotibial (75 arm vein, 23 composite); femoropedal (14 arm vein, 6 composite), and popliteo-tibial/pedal (21 arm vein, 0 composite). The indication for surgery was limb salvage in 98% and disabling claudication in 2% of cases. The mean follow-up was 25.1 months (range, 1 month to 7.9 years). Overall survival at 4 years was 51%. Overall patency and limb salvage rates were as follows: primary patency, at 1 year-arm vein, 76.9% +/- 4.8%; composite, 59. 5% +/- 9.6% (P =.02); at 3 years-arm vein, 70.0% +/- 8.0%; composite, 43.7% +/- 12.4% (P <.01); and at 5 years-arm vein, 53.8% +/- 8.7%; composite, 0%; secondary patency, at 1 year-arm vein, 77.5% +/- 4. 6%; composite, 59.8% +/- 9.5% (P =.02); at 3 years-arm vein, 70.7% +/- 7.5%, composite, 44.9% +/- 13.1% (P <.01); at 5 years-arm vein, 57.7% +/- 8.0%; composite, 0%; limb salvage, at 1 year-arm vein, 89. 3% +/- 3.7%; composite, 73.9% +/- 8.9% (P <.01); at 3 years-arm vein, 80.5% +/- 7.0%; composite, 49.6% +/- 14.3% (P <.01); at 5 years-arm vein, 76.3% +/- 9.9%; composite, 0%. CONCLUSION: In this study, multisegment autogenous arm vein was used successfully in a wide variety of lower extremity revascularization procedures and achieved good long-term patency and limb salvage rates, well in excess of those achieved with composite prosthetic-autogenous grafts. The use of autogenous conduit appears to offer superior results to composite conduit in lower extremity revascularization. The superior durability of arm vein makes it one of the alternative conduits of choice when an adequate greater saphenous vein is not available.     

下肢静脉造影在下肢静脉曲张患者中的应用及阻塞性下肢静脉曲张发生的预测因素

目的 探讨下肢静脉造影检查在下肢静脉曲张中应用的临床意义,并分析阻塞性下肢静脉曲张可能相关的预测因素.方法 选取2019年1月至2021年12月因下肢静脉曲张于海军军医大学第二附属医院诊治的74例患者(111条患肢)为研究对象,对所有患肢行下肢静脉造影检查,采用病例报告表形式记录患者相关信息,根据有无深静脉阻塞表现分为...     

Short saphenous vein grafts as an aid to microsurgical reconstruction of the lower extremity

The authors present a method of free flap reconstruction using the short saphenous vein, when local vessels are not available in the lower extremity. Initially, a temporary arteriovenous fistula is created. This is subsequently divided to provide both arterial access and venous drainage for the flap. The use of the short saphenous vein has a number of advantages: 1) forty to 50 cm of length are available; 2) the vein is relatively thin-walled and has a nearly constant diameter throughout its length; 3) the vein may be left in situ at its upper end in some patients; 4) the vein drains into both the long saphenous and the popliteal veins. Thus, double drainage is provided. This may be of importance in patients with impaired outflow secondary to deep venous thrombosis or obstruction. 5) The separated vein graft components allow accurate ultrasonic monitoring of both arterial and venous circulation. Seven cases are presented of type IIIb and IIIc tibial fractures in which regional vessels were not accessible. Free flap reconstruction using in situ short saphenous vein grafts was successful in all seven patients. The anatomy of the short saphenous vein and surgical technique are considered.