Surgical and endovascular intervention for infrainguinal vein graft stenosis

PURPOSE: The purpose of this study was to evaluate the stenosis-free patency of open repair (vein-patch angioplasty, interposition, jump grafting) and percutaneous transluminal balloon angioplasty (PTA) of 144 vein graft stenoses that were detected during duplex scan surveillance after infrainguinal vein bypass grafting. METHODS: Patients who underwent revision of an infrainguinal vein bypass graft were analyzed for type of vein conduit, vascular laboratory findings leading to revision, repair techniques, assisted graft patency rate, procedure mortality rate, and restenosis of the repair site. RESULTS: The time of postoperative revision ranged from 1 day to 133 months (mean, 13 months). One hundred eighteen primary and 26 recurrent stenoses (peak systolic velocity, >300 cm/s) in 52 tibial and 35 popliteal vein bypass grafts were identified by means of duplex scanning. The repairs consisted of 77 open procedures (vein-patch angioplasty, 28; vein interposition, 33; jump graft, 9; primary repair, 3) and 67 PTAs. No patient died as a result of intervention. Cumulative assisted graft patency rate (life-table analysis) was 91% at 1 year and 80% at 3 years. At 2 years, cumulative assisted graft patency rate was comparable for saphenous vein grafts (reversed, 94%; in situ, 88%; nonreversed, 63%) and alternative vein grafts (89%). Stenosis-free patency rate at 2 years was identical (P =.55) for surgical intervention (63%) and endovascular intervention (63%) but varied with type of surgical revision (P =.04) and time of intervention (<4 months, 45%; >4 months, 71%; P =.006). The use of duplex scan-monitored PTA to treat focal stenoses (<2 cm) and late-appearing stenoses (>3 months) was associated with a stenosis-free patency rate that was 89% at 1 year. After intervention, the alternative vein bypass grafts necessitated twice the reinterventions per month of graft survival (P =.01). Bypass graft to the popliteal versus infrageniculate arteries, site of graft stenosis (vein conduit, anastomotic region), and repair of a primary versus a recurrent stenosis did not influence the outcome after intervention. CONCLUSION: The revision of duplex scan-detected vein graft stenosis with surgical or endovascular techniques was associated with an excellent patency rate, including when intervention on alternative vein conduits or treatment of restenosis was necessary. When PTA was selected on the basis of clinical and duplex scan selection criteria, the endovascular treatment of focal vein graft stenosis was effective, durable, and comparable with the surgical revision of more extensive lesions.     

Surgical treatment of threatened reversed infrainguinal vein grafts

PURPOSE: Current information concerning the results of surgical revision of threatened infrainguinal vein grafts is largely limited to in situ conduits. Infrainguinal grafts may be threatened by intrinsic graft lesions or significant stenosis in the adjacent inflow or outflow arteries. To assess the results of operative revision of infrainguinal reversed vein grafts, we reviewed our experience with surgical revision of threatened infrainguinal reversed vein grafts identified through a program of postoperative clinical and vascular laboratory graft surveillance. METHODS: All patients who underwent surgical revision of a threatened but patent infrainguinal reversed vein graft from January 1987 through April 1993 were identified through review of our vascular registry. Data were analyzed for type of vein used, date of original reversed vein graft, clinical and vascular laboratory findings leading to reversed vein graft revision, results of preoperative angiography, patient risk factors, operative techniques and complications, and long-term assisted primary graft patency and limb salvage. RESULTS: Ninety-six patients with 100 infrainguinal reversed vein grafts (69) femoral-popliteal, 31 femoral-tibial) underwent 117 surgical vein graft revisions or inflow procedures during the study period. Eighty-one percent of the original reversed vein grafts consisted of a single segment of greater saphenous vein. All revised grafts had at least a 50% stenosis in the graft itself or the proximal or distal artery. A single revision was performed in 85 grafts, two revisions in 13 grafts, and three revisions in two grafts. There were nine (8%) isolated inflow procedures, eight (7%) vein patch angioplasties, 62 (53%) interposition vein grafts, and 29 (25%) vein graft extensions to a new distal anastomotic site. The remaining nine (8%) procedures consisted of combinations of the above. Median time to primary graft revision after initial graft implantation was 15 months (range 2 days to 316 months). Mean time to secondary revision after primary revision was 21 months. Operative mortality was 0.9%. Cumulative assisted primary patency of the original grafts revised for stenotic lesions was 99%, 96%, and 92% at 1, 3, and 5 years, respectively. Limb salvage was 99%, 97%, and 97% at 1, 3, and 5 years, respectively. CONCLUSIONS: Although surgical revision of reversed vein graft requires much use of alternative vein sources, these procedures can be performed with minimum mortality and provide excellent assisted primary graft patency and limb salvage.     

Intraoperative control following femorodistal revascularization: angioscopy is superior to angiography

Intraoperative angioscopic control was performed in an early series of 27 patients undergoing peripheral vascular surgery. The majority were complex or re-do operations; reversed saphenous vein and PTFE-grafts were used as bypass material exclusively. Angioscopic findings were compared to conventional angiography with respect to the detection of technical problems leading to further surgical procedures. Angioscopy was feasable in 92.5%, it failed twice due to irrigation problems, which was before we used a dedicated angioscopy roller-pump. In 6 patients relevant findings requiring further surgical manipulations were only detected angioscopically, in 2 patients such findings were detected by angioscopy as well as by angiography. Such findings included technical problems (graft rotation [n = 1], anastomotic narrowing [n = 2]), balloon catheter injuries after thromboembolectomy (n = 2) and residual thrombi after local thrombectomy (n = 3); 5 of these patients had undergone previous vascular procedures in the same operation field. After local correction (n = 5) or placement of a new bypass (n = 3) there was no early graft failure. This early angioscopic experience confirmed previous reports that satisfactory visualization and specific recognition of angiographically unsuspected problems after peripheral reconstructions can be obtained by intraoperative angioscopic control. This was seen very distinctively in more complex and re-do operations, which we see as the cases most needing routine angioscopic control.     

Very distal bypass for salvage of the severely ischemic extremity

Forty-six bypass grafts to tibial arteries distal to the ankle were performed in 35 patients for salvage of extremities threatened by gangrene or nonhealing ulcers (grade III, category 5) or ischemic rest pain (grade II, category 4). Most patients (80%) were diabetic, with severely calcified arteries, whom previously we would have considered as candidates for primary amputation. All reconstructions were performed with autologous saphenous vein. Inflow was from the common femoral artery in 5 (11%), the popliteal artery in 25 (54%), or the mid-tibial arteries in 16 (35%). Life-table analysis was used to calculate primary patency and limb salvage. Results were analyzed according to origin of inflow, outflow, or configuration of the conduit (in situ saphenous vein, n = 29 [63%], reversed saphenous vein, n = 11 [24%], or nonreversed saphenous vein, n = 6 [13%]). Overall cumulative primary graft patency at 2 years for all grafts was 72%, and the cumulative limb salvage rate was 89% for the same interval. No significant differences were seen in comparing grafts originating from the femoral or popliteal level with those arising from the tibial arteries. No significant differences were noted in graft patency or limb salvage among grafts with a posterior tibial, dorsalis pedis, or plantar artery outflow. No significant difference was noted between in situ saphenous vein grafts and reversed saphenous vein grafts. A significant decreased primary patency was noted for grafts performed with nonreversed, translocated saphenous vein. We conclude that bypass grafts to the ankle or foot vessels are beneficial and should be considered for limb salvage in extremities with gangrene, ischemic ulceration, or ischemic rest pain. In our experience, in situ saphenous vein grafts or reversed saphenous vein grafts performed similarly, whereas nonreversed saphenous vein grafts have a poorer prognosis. Vessel wall calcification requires a modification in technique for performance of these grafts but did not affect long-term performance or limb salvage, and thus should not be considered a contraindication to vascular reconstruction. The operative microscope was used in 61% (28 of 46) of these cases and found useful in creating these delicate anastomoses. Additional follow-up is needed to document the long-term results of these very distal reconstructions.     

Spontaneous regression of intraspinal neuroblastoma

The superiority of vein over polytetrafluoroethylene (PTFE) as a bypass conduit for grafts ending below the knee makes it the material of choice for this purpose. When insufficient long saphenous vein is available, lengths of arm vein may be used as a satisfactory alternative to make a composite graft. This may cause confusion in subsequent graft surveillance programs as the arm vein segment may show different characteristics from the remainder of the graft. We report a case where a stenosis developed in the arm vein segment of a bypass graft which subsequently ruptured during balloon angioplasty with formation of a false aneurysm. This was due to the balloon size being selected on the basis of the size of the long saphenous vein section of the graft instead of the arm vein segment. Full communication between surgeon and radiologist must include complete details of all materials used in bypass grafts in order to avoid potentially disastrous results from angioplasty.     

Preferred strategies for secondary infrainguinal bypass: lessons learned from 300 consecutive reoperations

PURPOSE: To determine the optimal surgical strategies in reoperative infrainguinal bypass, we reviewed our results in 300 consecutive secondary bypasses in 251 patients operated on between Jan. 1, 1975, and Nov. 1, 1993. METHODS: There were 168 men (67%) and 83 women (33%), with a mean age of 64.8 years and a typical distribution of risk factors including smoking (76.4%), diabetes (33.7%), and coronary artery disease (47.1%). The indications for surgery were limb-threatening ischemia in 83.5% and severe claudication in 16.5% of patients. The majority of conduits (n = 213) were autogenous vein and were composed of a single segment of greater saphenous vein in 121 bypasses (57%) and various alternative veins including composite, arm, and lesser saphenous vein in 92 bypasses (43%). Prosthetic conduits included 69 polytetrafluoroethylene, 16 umbilical vein, and two Dacron grafts. RESULTS: There was one perioperative death (0.3%) and a 25% total morbidity rate including a 1.7% myocardial infarction rate. There was a 28.6% early (< 30 days) graft failure and 10.7% early amputation rate for prosthetic bypass grafts compared with 13.6% early graft failure and 5.6% early amputation rates for vein grafts. Autogenous vein bypasses had higher 5-year secondary patency rates than had prosthetic grafts (51.5% +/- 4.6% vs 27.4% +/- 6.1%, p < 0.001). Results with autogenous vein bypass improved significantly from the 1975 to 1984 to the 1985 to 1993 interval with 5-year secondary patency rates increasing from 38.3% +/- 6.9% to 59.1% +/- 5.8% (p = 0.017) and 5-year limb-salvage rates increasing from 40.4% +/- 7.6% to 72.4% +/- 6.6% (p < 0.001). Vein grafts to the popliteal and tibial outflow levels had equivalent long-term results. Vein grafts completed for claudication demonstrated results superior to those for limb salvage, with a 5-year secondary patency rate of 75.8% +/- 8.1% versus 52.3% +/- 7.9% (p = 0.048). Secondary autogenous vein bypass grafting performed after early primary graft failure (< 3 months) did particularly poorly, with only a 27.2% +/- 7.7% 4-year secondary patency rate. Greater saphenous veins tended to perform better than alternative vein bypasses, with a 5-year secondary patency rate of 68.5% +/- 6.0% compared with 48.3% +/- 10.5% (p = 0.09) and a 5-year limb-salvage rate of 77.8% +/- 7.4% versus 54.2% +/- 11.8% (p = 0.046). CONCLUSIONS: When patients suffer a recurrence of limb-threatening ischemia at the time of infrainguinal graft failure, aggressive attempts at secondary revascularization with autogenous vein are warranted based on the low surgical morbidity and mortality rates and the improved patency and limb salvage rates that are currently attainable.     

Ultrasonographic evaluation of the anterior recess in the normal hip: a prospective study on 166 asymptomatic children

Bypass graft patency with ultrafast computed tomography (= Electron Beam Tomography, EBT) was examined in 72 bypass grafts (47 saphenous veins, 25 internal mammary arteries) in 30 patients and compared with coronary angiography. Angiography was performed a mean of 4.4 +/- 3.5 months (range 1-13) from the EBT examination. Contrast material (120 ml) was continuously administered via a peripheral vein and 40 axial slices (3 mm slice thickness, 110 ms scan time) without overlap sequences were obtained, ECG triggered with the single slice scanner mode. Imaging of internal mammary artery grafts began at the thoracic inlet, for saphenous vein grafts, at the undersurface of the aorta. Sixty of 63 angiographically patent bypass grafts were determined patent by EBT (sensitivity 95%), 8 bypass grafts could not be detected by EBT, and 9 were angiographically occluded (specificity 89%). Twenty-four of 25 internal mammary artery grafts were patent at EBT and coronary angiography, one was occluded. In 27 of the 30 patients (90%), all of the angiographically patent grafts could be confirmed as open with EBT. Obstructions of 10 grafts could not be visualized with EBT. Graft insertion into native coronary vessels could be visualized in axial slices, although morphologic quantification of graft insertion stenosis (75-90%) in two cases was not possible. Three dimensional reconstruction of the 40 axial slices allowed graft anatomy to be delineated. Visualization of bypass insertion into the native coronary vessel was less successful because of opacification of the left and right ventricle. Electron beam computed tomography is a minimally invasive procedure capable of evaluating the patency of saphenous vein and internal mammary artery grafts. The morphologic quantification of graft obstruction and visualization of the insertion of the bypasses into the native coronary vessels is less successful with present technology and imaging modalities.     

Value of reversed saphenous vein in minimally invasive direct coronary artery bypass graft procedures

BACKGROUND: Minimally invasive direct coronary artery bypass graft procedures are gaining acceptance for revision as well as primary coronary revascularization. When suitable, the left and right internal mammary arteries are preferred as bypass conduits; in other cases, the greater saphenous vein, used for standard coronary artery bypass graft procedures, may be useful to revascularize coronary artery branches during minimally invasive direct coronary artery bypass graft procedures. METHODS: We used the greater saphenous vein on three occasions during minimally invasive direct coronary artery bypass graft procedures (1) to revascularize the left anterior descending coronary artery by anastomosis to the left axillary artery in the infraclavicular region, (2) as an extension to the left internal mammary artery to reach the left anterior descending coronary artery, and (3) as a bridge from the splenic artery to bypass the distal right coronary artery. RESULTS: Postoperatively, all 3 patients had relief from symptoms of coronary artery insufficiency and none has been readmitted to the hospital with symptoms. Angiography or thallium studies were not performed to confirm graft patency because all patients were elderly and the risks of these procedures were considered to outweigh their potential benefit. CONCLUSIONS: The greater saphenous vein is a potential bypass conduit for use in minimally invasive direct coronary artery bypass graft procedures as well as for coronary artery bypass graft procedures.     

Lower limb surveillance following autologous vein bypass should be life long

BACKGROUND: The aim of the study was to investigate whether infrainguinal vein graft surveillance can be stopped at 1 year without prejudicing graft or leg survival. METHODS: Data were collected prospectively on 351 infrainguinal vein bypass grafts (326 patients) that had been entered into a vein graft surveillance programme between 1988 and 1997. RESULTS: Some 104 grafts (30 per cent) developed significant new vein graft stenoses, 95 (91 per cent) of which occurred within 12 months. After 1 year, the risk of developing a significant graft stenosis was 3 per cent per year. Sixty-nine grafted limbs (20 per cent) developed new arterial inflow or run-off stenoses that required intervention, but only 37 (54 per cent) occurred within the first year, after which the risk was 9 per cent per year. The overall risk of developing a new vein graft or arterial stenosis after 1 year was 10 per cent per year. CONCLUSION: The incidence of vein graft stenosis decreases significantly 1 year after operation but there is still at risk of developing potentially graft-threatening arterial stenoses. Legs that have undergone infrainguinal vein bypass grafting should continue to be monitored in a surveillance programme for life.     

The relationship between arm-ankle pressure difference and peak systolic velocity in patients with stenotic lower extremity vein grafts

The relationship between the measured arm-ankle pressure difference (AAPD), or the ankle/arm index (AAI), and the focal peak systolic velocity (PSV) at stenotic sites of infrainguinal vein grafts has not been determined. We attempted to relate these two parameters. We used Doppler systolic pressures and duplex ultrasonography to study 35 infrainguinal vein bypass grafts followed in a surveillance protocol. The following graft groups were identified: grafts in nondiabetic patients (n = 26), grafts in diabetic patients (n = 9), nonrevised stenotic grafts (n = 14), revised stenotic grafts (n = 14), and normal grafts (n = 7). AAPD and AAI were measured in both lower extremities. Pressure gradients across graft stenoses were indirectly estimated using the modified Bernoulli equation (delta P =4V2). Measured AAPDs and estimated pressure gradients showed moderate correlation in nondiabetic (r = 0.58) and diabetic (r = 0.63) patients. Correlation was fair (r = 0.3) prior to graft revision. There was no correlation (r = 0.1) in the nonrevised stenotic grafts. For individual patients with stenotic grafts who were followed in consecutive visits, the correlation varied from none to good (r range 0.01 to 0.71). We conclude that there is a lack of consistent correlation between the measured AAPD, or AAI, and the estimated stenotic graft pressure gradient. This finding illustrates the limitation of the AAI as a monitoring test to predict failure of stenotic infrainguinal vein grafts.     

The choice of material for above-knee femoropopliteal bypass. A 20-year experience

OBJECTIVE: The choice of material for above-knee femoropopliteal bypass grafting is a matter of continuing controversy for various reasons. The most important argument in favor of alloplastic grafts is to preserve the autologous saphenous vein for a below-knee bypass, which might become indicated at a later date. DESIGN: A consecutive series of above-knee reconstructions were analyzed with regard to long-term behavior. Early graft occlusions were not included, and the median follow-up was 83 months. SETTING: A university hospital with a particular interest in vascular surgery. PATIENTS AND METHODS: Four hundred forty-two patients received either autologous saphenous vein (n = 310) or alloplastic graft (n = 132) material, and were analyzed in a univariate (Kaplan-Meier) and multivariate (Cox) manner. MAIN OUTCOME MEASURES: Analysis as to whether alloplastic graft material provides equal or less favorable results as compared with autologous saphenous vein material, in terms of primary and secondary patency, secondary below-knee bypass grafting, limb salvage, and survival. RESULTS: Although univariate analysis demonstrated a significantly better primary patency rate for autologous saphenous vein material, multivariate analysis did not show any effect of the material in terms of patency, limb salvage, and survival. The frequency of secondary below-knee repair was 7% (31 patients); 56% were performed in the first 2 years postoperatively. This amounted to an estimated probability of 4.4% and 12.3% at 18 years, respectively. CONCLUSION: The small probability of secondary below-knee repair in our series does not support the policy to use alloplastic grafts routinely for a primary above-knee bypass, to spare the saphenous vein. Therefore, patients should be offered the best material for the first operation even at the above-knee level.     

Impact of inflow reconstruction on infrainguinal bypass

PURPOSE: This study assessed whether multisegmental disease that is severe enough to require an inflow procedure adversely affects infrainguinal bypass patency, limb salvage, or patient survival rates. METHODS: The records of 495 patients who underwent 551 infrainguinal bypass grafting procedures were reviewed. Saphenous vein and prosthetic grafts were evaluated separately. Graft patency rates, patient limb salvage rates, and patient survival rates in those grafts that arose from a reconstructed inflow source were compared with those that arose from normal, nonreconstructed inflow sources. When grafts had either hemodynamic failure or occlusion, the cause of failure was identified. RESULTS: Four-year primary patency rates in vein grafts that arose from a reconstructed inflow sources were lower than those in grafts that arose from nonreconstructed inflow sources (41% vs 54%; p = 0.006). Assisted primary patency rates and secondary patency rates, however, were similar (62% vs 74% and 64% vs 77%, respectively). The 4-year primary patency rate (45% vs 55%), assisted primary patency rate (60% vs 60%), and secondary patency rate (60% vs 61%) in prosthetic grafts did not vary based on inflow source. The most common cause of graft failure was inflow failure, except in the vein grafts that did not require an inflow procedure, in which the most common cause of failure was graft failure. Inflow failure occurred in 24% and 22% of the vein and prosthetic grafts with multisegmental disease, respectively, but in only 7% (p < 0.001) and 10% (p < 0.05), respectively, of those that arose from normal nonreconstructed inflow. The presence of an inflow procedure did not affect limb salvage rates or patient survival rates, regardless of graft material. CONCLUSIONS: Long-term patency rates, patient limb salvage rates, and survival rates in patients with a reconstructed inflow source were similar to those of patients with a normal nonreconstructed inflow. A major cause of occlusion is inflow failure, and this occurs in a greater proportion of patients with multisegmental disease. These patients, in particular, may benefit from patient surveillance to screen for progression of their inflow disease and to allow for intervention before infrainguinal graft occlusion.     

Quality control in peripheral vascular surgery

Indications and modalities of quality control in infrainguinal bypass surgery are reviewed and discussed. A concept and an armamentarium for its practical use are presented. The majority of graft occlusions occur during the first postoperative year. Most failures in the first month are due to technical errors. Many of these can be detected by intraoperative completion control, and immediately repaired. This contributes to improved graft patency rates. In the further course, myo-intimal hyperplasia accounts for most graft stenoses and occlusions. If stenoses are detected and dilated before occlusion occurs, long-term patency is but little impaired. Conversely, patency rates are clearly inferior in grafts following thrombectomy or thrombolysis. Therefore, identification of failing grafts and avoidance of failure are the objectives of surveillance. We have followed routinely a surveillance program since 1991. During surgery, grafts were controlled by completion angiography. Arterial pressures were measured and the ankle-brachial index calculated postoperatively and 1, 3, 6 and 12 months after surgery. In addition, a number of grafts were followed by duplex sonography. Data were stored in an electronic data base featuring several interactive functions. E.g., ankle-brachial and duplex-sonography indices were calculated and rated automatically according to current criteria. Secondary patency after 18 months was 86 per cent in suprageniculate femoro-popliteal bypass grafts, 84 per cent in infrageniculate and 65 per cent in crural (n = 19/23/27).     

Mesh tube-calibrated varicose veins for coronary artery bypass grafting

Complex arterial bypass grafting may be contraindicated for patients with multivessel disease and inadequate saphenous veins. In such cases varicose veins may be used as bypass conduits after calibration by insertion into mesh tubes. After in vitro and experimental testing, as well as gratifying results in infrainguinal arterial reconstructions, wrapped varicose vein grafts in addition to arterial bypass grafts were used in 6 patients undergoing coronary artery bypass grafting.     

Purification and characterisation of a tripeptidyl aminopeptidase I from rat spleen

Proliferation of vascular smooth muscle cells (VSMC) is a principal event in neointima formation in saphenous vein-coronary artery bypass grafts. Since endothelin-1 (ET-1) promotes VSMC replication and ET-1 receptor antagonists inhibit neointima formation in arterial injury models, it is reasonable to propose that ET-1 may be involved in neointima formation in vein grafts. However, it is not known what alterations of ET-1 and its receptors (if any) occur in vein grafts. The objective of this study, therefore, was to investigate the distribution of ET-1 and ET-1 receptor subtypes (ET(A) and ET(B)) in porcine vein grafts. Unilateral interposition saphenous vein grafting was performed by end to end anastomosis after excision of a segment of carotid artery in Landrace pigs. One month after surgery, vein grafts, ungrafted saphenous veins and carotid arteries were excised, ET-1 immunoreactivity identified by immunocytochemistry and ET(A) and ET(B) receptor subtypes studied using autoradiography. In vein grafts, there was a greater density of ET(A) compared to ET(B) receptors in both the tunica media and neointima. ET(A) binding in the tunica media of ungrafted saphenous vein was greater than that in the carotid artery or vein grafts, but greater in the vein graft compared to the carotid artery. Immunoreactive ET-1 was located in endothelial cells and throughout the neointima of the vein graft. Dense ET-1 binding (to both ET(A) and ET(B) receptors) was also associated with microvessels in the adventitia within the graft. In vein grafts, there was strong ET(B) binding to neutrophils which were present in high numbers at the subendothelium and within the adventitia. It is concluded ET(A) receptors may play a role in vein graft thickening at the medial and neointimal VSMC level, whereas ET(B) receptors may play a role in microangiogenesis. The higher levels of ET(A) receptors in the tunica media of ungrafted saphenous vein relative to the carotid artery and vein graft may also render this conduit susceptible to neointima formation. These data indicate that studies on the effect of ET receptor antagonists on the pathobiology of vein graft disease is warranted.     

Early results with cryopreserved saphenous vein allografts for infrainguinal bypass

PURPOSE: Cryopreserved saphenous vein allografts (CSVA) are available for use in arterial reconstructions; however, patency rates in the infrainguinal position are not well described. METHODS: We reviewed our experience with 38 patients who underwent 43 infrainguinal bypasses with CSVA as the conduit. The group includes 21 women and 17 men with a mean age of 69 +/- 11 years. Mean follow-up is 8.2 +/- 5.5 months. Logistic regression was used to analyze five variables in an attempt to identify predictors of success or failure: distal anastomosis to the popliteal artery versus a crural artery, one-vessel versus two- or three-vessel runoff, postoperative anticoagulation versus none, primary reconstructions versus reoperations, and one segment versus two segments of CSVA required. RESULTS: The cumulative patency rate at 12 months by life-table analysis is 66%. Logistic regression revealed that primary reconstructions were more likely to succeed than reoperations (p = 0.03) and operations completed with one segment of CSVA were more likely to succeed than those requiring more than one segment of vein (p = 0.03). CONCLUSIONS: We conclude that (1) the short-term patency of infrainguinal bypasses with CSVA suggests that they may be acceptable alternatives to prosthetic grafts in the below-knee position, and (2) primary reconstructions performed with one segment of CSVA are more likely to succeed.     

Aneurysm of a subclavian-vertebral artery saphenous vein bypass graft: case report

OBJECTIVE AND IMPORTANCE: Although an autogenous saphenous vein is frequently used as a bypass graft, an aneurysm of a venous graft is a rare complication, especially in the case of cerebrovascular revascularization. We report a case of a successfully treated aneurysmal change in a venous graft after short vein bypass grafting. CLINICAL PRESENTATION: A 60-year-old man underwent a left subclavian-to-vertebral artery bypass operation with an interposed saphenous vein graft because of severe stenosis of the vertebral artery bilaterally. Angiograms of the left subclavian artery, obtained 4 months later, showed good patency of the graft without any dilation or stenosis. One year after the bypass surgery, the patient became aware of a pulsating mass in the left supraclavicular region, which was regarded as the grafted vein itself. A giant aneurysm of the vein graft, which developed at the nonanastomotic site, was shown in the angiogram 4 years later. INTERVENTION: The aneurysm was resected, and patch grafting of the orifice of the aneurysmal neck covered with an artificial vessel as a reinforcement was performed. CONCLUSION: The aneurysm seemed to have developed in a curved segment because of hemodynamic stress.     

New stent technologies

Poor long-term patency of saphenous vein grafts limits the long-term success of the coronary artery bypass operation. If this is to be improved, either measures that increase the patency of saphenous vein grafts or alternative conduits are required. The benefits of using the left internal mammary artery as a pedicled graft to the left anterior descending coronary artery have prompted increasing use of arterial grafts to further improve outcome. Concurrently advances in the understanding of the pathological processes underlying saphenous vein graft occlusion raise the possibility of improving vein graft patency. In this paper we review the problem of vein graft occlusion and possible solutions, the theoretical benefits of arterial grafts and the clinical results associated with their use.     

Constitutive nitric oxide synthase is expressed and nitric oxide-mediated relaxation is preserved in retrieved human aortocoronary vein grafts

Although little is known about the endothelial cell function of human saphenous vein coronary artery bypass grafts, there is evidence to suggest that receptor-activated, endothelial-dependent relaxation mediated by nitric oxide is impaired. This study examines the expression and function of endothelial cell constitutive nitric oxide synthase (cNOS) of aortocoronary vein bypass grafts and human saphenous veins obtained from 10 patients undergoing repeat coronary artery bypass grafting for recurrent ischemic symptoms. Following precontraction with norepinephrine (10(-5) M), responses to acetylcholine (receptor-mediated, endothelium-dependent), calcium ionophore (A23187; receptor-independent, endothelium-dependent), and sodium nitroprusside (endothelium-independent) were assessed. Following total RNA extraction using phenol/guanidinium isothiocyanate from specimens of human saphenous vein and vein graft, a quantitative RNase Protection Assay (RPA) was performed using a cRNA riboprobe corresponding to a fragment of the human endothelial cell cNOS gene. Histologically, the vein grafts showed both intimal hyperplasia development and focal atherosclerosis formation compared to the saphenous veins. Scanning electron microscopy of the saphenous veins and the vein grafts showed an intact endothelium. Precontracted vein grafts did not relax in response to acetylcholine; in contrast, the saphenous vein relaxed in a dose-dependent manner to reach a maximal relaxation of 19 +/- 4% precontracted tension. Saphenous veins and vein grafts relaxed in response to A23187 with maximal relaxation of 92 +/- 5 and 73 +/- 13%, respectively. Both vessels relaxed in a dose dependent manner to sodium nitroprusside. RPA normalized to beta-actin showed similar levels of expression of endothelial cell cNOS equivalent to 1 pg of sense RNA in both the saphenous vein and vein graft.(ABSTRACT TRUNCATED AT 250 WORDS)     

Insonation and impedance analysis in graft surveillance

Seventy consecutive patients with infrainguinal bypass grafts entered a 1-year graft surveillance programme involving colour duplex scanning, direct graft insonation and computer-assisted impedance analysis. Graft patients with a positive duplex scan, high frequencies on graft insonation or an impedance value above 0.50 subsequently underwent arteriography. Sixteen patients were excluded before the initial surveillance visit. The 54 remaining patients with grafts (30 vein, 24 synthetic) underwent a total of 137 surveillance visits, with 21 grafts confirmed to be 'at risk'. The sensitivity of an impedance value above 0.55 in identifying these grafts was 86 per cent, rising to 95 per cent when combined with graft insonation. Duplex scanning did not identify any abnormalities in 11 grafts that were either shown by arteriography to be 'at risk' or occluded before arteriography. Impedance measurement and graft insonation are simple screening techniques with a high sensitivity (when combined), which identify 'at risk' infrainguinal grafts. Positive graft insonation or an impedance value over 0.55 will identify all 'at risk' vein grafts while minimizing the number of unnecessary arteriograms.