Cryopreserved saphenous vein allografts in infrainguinal arterial reconstruction

Cryopreserved saphenous vein allografts (cryografts) have been used as conduit in infrainguinal revascularization when autogenous vein is inadequate or unavailable. Numerous reports on the subject exist, however most are hampered by small sample size or retrospective design. Despite poor patency rates, limb salvage in patients undergoing cryograft bypass is acceptable. In this article we review the literature of cryograft use in infrainguinal revascularization and define its role in the armamentarium of the modern vascular surgeon.     

Cryopreserved saphenous vein allografts for below-knee lower extremity revascularization.

OBJECTIVE: Cryopreserved saphenous vein allografts have been offered as an alternative conduit for bypass in ischemic limbs. The authors examined the efficacy of this conduit for arterial bypass to the distal popliteal and tibial arteries in patients in whom autogenous vein was not available. SUMMARY BACKGROUND DATA: Previous experience with arterial and venous allografts has been unsatisfactory because of aneurysmal degeneration and poor patency. Endothelial loss and host rejection have been suggested as mechanisms of graft failure. Cryopreservation by modern techniques with rate controlled freezing, dimethyl sulfoxide (DMSO), and other cryopreservants, has addressed these issues and rekindled interest in vein allografts. METHODS: Over a period of more than 5 years, 115 cryopreserved vein allografts were implanted in 87 limbs to the distal popliteal (14) or tibial (101) arteries. The indication for surgery was rest pain in 56 procedures (49%), gangrene in 36 (31%), claudication in 21 (18%), and replacement of aneurysmal allografts in 2. Follow-up was 1 to 61 months (mean 25 months). RESULTS: There was no significant difference in patency related to site of proximal or distal anastomosis, patency of runoff vessels, use of anticoagulation, age, sex, diabetes, hypertension, smoking, indication, source of graft, or use of multiple segments. Revision was required in six grafts for aneurysmal dilatation. Histologic examination of explanted sections of allografts showed no immune response, and immunosuppressive drugs were not used. CONCLUSIONS: Although limb salvage has been satisfactory, long-term patency rates for cryopreserved vein allografts are poor when compared with autogenous vein. The cost of cryopreserved allografts far exceeds that of prosthetic grafts, for which comparable and superior results have been reported. Use of cryopreserved vein allografts should be reserved for situations in which adequate lengths of autogenous vein do not exist and the risk of infection of prosthetic grafts is high.     

A comparison of in situ and reversed saphenous vein grafts for infrainguinal reconstruction

Despite the recent popularity of the in situ saphenous vein graft for infrainguinal arterial reconstruction, considerable doubt exists as to whether this approach offers any real advantage over conventional reversed vein grafts. Therefore we have reviewed our experience with 675 infrainguinal vein grafts undertaken during the past 10 years. There have been no substantial modifications in the technique used for 535 reversed vein grafts over the 10-year period. During the past 3 years, 140 in situ vein grafts have been carried out with the Leather valvulotome used to incise the venous valves. Life-table analysis of 449 femoropopliteal reversed saphenous vein grafts demonstrated 1- and 3-year cumulative patency rates of 81% and 73%, respectively, and a 5-year patency rate of 63%. Seventy-five femoropopliteal in situ bypasses demonstrated a patency rate of 85% at both 1- and 3-year intervals. Cumulative patency rates for 86 femoroinfrapopliteal reversed saphenous vein grafts were 64% and 62% at 1 and 3 years, respectively. Comparable patency rates for 65 infrapopliteal in situ saphenous vein grafts remained stable at 87% for 3 years. Fifteen of the in situ bypasses were anastomosed to vessels at the ankle or foot level, whereas none of the reversed bypasses was carried that far distally. This experience with both in situ and reversed techniques on one service by the same surgeons demonstrates a clear superiority of the in situ saphenous vein graft for infrapopliteal reconstruction at the 3-year interval.     

Real-time duplex ultrasound mapping of the greater saphenous vein before in situ infrainguinal revascularization

From November 1983 through September 1985, 102 greater saphenous veins (GSVs) were assessed and mapped by means of real-time duplex ultrasonic scanning before in situ infrainguinal revascularization. Each GSV was also visually assessed at operation. Eighty-five GSVs were successfully used for infrainguinal revascularization; duplex scanning correctly identified 82 of these GSVs as being acceptable for use in in situ bypass. Seventeen GSVs were unacceptable for in situ bypass; duplex scanning correctly identified 11 of these as being unacceptable. Duplex scanning provides anatomic information about the GSV, including size, patency, course, varicosities, double segments, and tributaries. This information permits the surgeon to perform infrainguinal revascularization expeditiously.     

Surgical management: saphenous vein grafts

Peyronie's disease is a medically and surgically challenging condition to manage. Most surgical techniques to correct the penile deformity often shorten the penis and do not address the issue of hourglass deformity when present. We describe our indications, rationale and technique for the use of a saphenous vein graft after a curvature correcting plaque incision. In reviewing multiple series, this approach yields similar results-incidence of residual curvature: 4-20%, decreased potency: 5-20%, penile shortening: 17-40%. While harvesting the vein would require a second incision, the use of autologous vein appears to be associated with the least amount of intracavernosal fibrosis. We propose that saphenous vein is currently the best material available for tunical patching. The technique and results of circular venous grafting for patients with severe penile shortening secondary to Peyronie's disease is also discussed.     

Angioscopy of arm vein infrainguinal bypass grafts

Between January 1988 and December 1990, 56 patients underwent 66 arm vein infrainguinal bypass grafts for limb salvage. Thirty-nine grafts were intraoperatively monitored by the standard methods of continuous wave Doppler alone (30) and arteriography (9). Twenty-seven grafts were prepared and monitored by intraoperative angioscopy. No significant findings requiring intraoperative revision or correction were noted in the grafts monitored by the standard methods. However, in those grafts prepared and monitored by angioscopy, intraluminal abnormalities of the arm veins were detected and corrected in 20/27 (74%). None of the grafts prepared or monitored by angioscopy occluded within 30 days, whereas, in those grafts monitored by continuous wave Doppler and arteriography, 7/39 failed within 30 days, a primary patency rate of 32/39 (82%) (x² with Yates correction, p=0.055). This study shows that angioscopic preparation and monitoring of arm vein bypass grafts allows the detection and correction of unsuspected intraluminal abnormalities, which appears to improve the early primary patency of arm vein infrainguinal bypass grafts.Presented at the Fifteenth Annual Meeting of the Peripheral Vascular Surgery Society, June 2, 1990, Los Angeles, California.     

Hemodynamics of stenotic infrainguinal vein grafts: Theoretic considerations

We developed a theoretic model of arterial stenosis to study the relationship between perfusion pressure and regional hemodynamics in stenotic infrainguinal vein grafts in an attempt to identify grafts at high risk for failure. Our model was based on the concept of energy and mass conservation of the flowing blood. We used the modified Bernoulli equation (P=4V²) to calculate the maximum possible intrastenotic peak systolic velocity (PSV) from the systolic blood pressure. PSV was measured by means of duplex ultrasonography in infrainguinal bypasses up to the time of revision (nine grafts) or spontaneous thrombosis (two grafts). We related arm systolic blood pressure, intrastenotic PSV, and prestenotic PSV obtained from duplex examinations conducted prior to graft thrombosis or revision and applied our model to these stenotic vein grafts. Intrastenotic PSV was consistently lower than maximum PSV predicted from the Bernoulli equation. The highest measured intrastenotic PSV of 600 cm/sec would require a minimum perfusion pressure of 144 mm Hg. The lowest measured PSV (20 cm/sec) was considered the minimum thrombotic threshold velocity. This model predicts that for parabolic profile flow in an 80% diameter-reducing axisymmetric stenosis (96% cross-sectional area reduction), a prestenotic PSV of 20 cm/sec would produce an intrastenotic PSV of 500 cm/sec requiring the equivalent potential energy of 100 mm Hg systolic blood pressure. Our theory implies that in patients with nocturnal hypotension thrombosis of stenotic vein grafts may occur.Supported by grant HL 42270 from the National Institutes of Health, Bethesda, Md.     

Six-year prospective multicenter randomized comparison of autologous saphenous vein and expanded polytetrafluoroethylene grafts in infrainguinal arterial reconstructions

Autologous saphenous vein (ASV) and polytetrafluoroethylene (PTFE) grafts were compared in 845 infrainguinal bypass operations, 485 to the popliteal artery and 360 to infrapopliteal arteries. Life-table primary patency rates for randomized PTFE grafts to the popliteal artery paralleled those for randomized ASV grafts to the same level for 2 years and then became significantly different (4-year patency rate of 68% +/- 8% [SE] for ASV vs. 47% +/- 9% for PTFE, p less than 0.025). Four-year patency differences for randomized above-knee grafts were not statistically significant (61% +/- 12% for ASV vs. 38% +/- 13% for PTFE, p greater than 0.25) but were for randomized below-knee grafts (76% +/- 9% for ASV vs. 54% +/- 11% for PTFE, p less than 0.05). Four-year limb salvage rates after bypasses to the popliteal artery to control critical ischemia did not differ for the two types of randomized grafts (75% +/- 10% for ASV vs. 70% +/- 10% for PTFE, p greater than 0.25). Although primary patency rates for randomized and obligatory PTFE grafts to the popliteal artery were significantly different (p less than 0.025), 4-year limb salvage rates were not (70% +/- 10% vs. 68% +/- 20%, p greater than 0.25). Primary patency rates at 4 years for infrapopliteal bypasses with randomized ASV were significantly better than those with randomized PTFE (49% +/- 10% vs. 12% +/- 7%, p less than 0.001). Limb salvage rates at 3 1/2 years for infrapopliteal bypasses with both randomized grafts (57% +/- 10% for ASV and 61% +/- 10% for PTFE) were better than those for obligatory infrapopliteal PTFE grafts (38% +/- 11%, p less than 0.01). These results fail to support the routine preferential use of PTFE grafts for either femoropopliteal or more distal bypasses. However, this graft may be used preferentially in selected poor-risk patients for femoropopliteal bypasses, particularly those that do not cross the knee. Although every effort should be made to use ASV for infrapopliteal bypasses, a PTFE distal bypass is a better option than a primary major amputation.     

Cryopreserved saphenous vein homografts for femoral-distal vascular reconstruction

Cryopreserved saphenous vein homografts may serve as an alternative for femoral distal bypass conduits when suitable endogenous vein is not available. In a preliminary study, 6 patients underwent femoral distal bypass for limb salvage with cryopreserved saphenous vein with patency in 2 patients at 18 and 20 months, respectively. One graft, occluded at 14 months, was salvaged with thrombolytic therapy and percutaneous angioplasty, and is patent 7 months post intervention. Occlusion occurred in 3 grafts at 1 day, 7 days and 4 months, respectively. Reasons for reduced patency of cryopreserved grafts are related to destruction of the cellular components and fibrosis as a result of the cryopreservation and poor distal run-off present in these patients. Due to lower patency as compared to autogenous vein grafts, cryopreserved veins should be reserved for limb salvage when no autogenous vein is available for revascularization.     

Thrombolysis of occluded infrainguinal vein grafts: Predictors of outcome

Purpose: The purpose of this study was to identify factors that influence graft patency and limb salvage rates after thrombolysis of occluded infrainguinal vein grafts.Methods: The records of patients who underwent percutaneous catheter-directed thrombolysis of occluded infrainguinal vein bypass grafts at our institution between 1985 and 1995 were reviewed. Life table analysis was used to determine survival and patency differences. Univariate and multivariate analyses were used to identify the patient-specific factors that affected outcomes.Results: Forty-four patients with 44 thrombosed infrainguinal vein grafts underwent thrombolysis with urokinase. The thrombolysis-related mortality rate was 2%, and nonfatal complications occurred in 16%. Thrombolysis was unable to restore graft patency in 25% of grafts (11 of 44). Of the remaining 33 successfully lysed grafts, 88% required adjunctive surgery or percutaneous transluminal angioplasty after thrombolysis. Overall, the primary graft patency rate was 25% at 1 year and 19% at 2 years after thrombolysis. Considering only successfully lysed grafts, the primary patency rate improved to 34% at 1 year and 25% at 2 years. Multivariate analysis revealed that the graft patency rate was substantially better in patients without diabetes and in vein grafts that had been in place for longer than 12 months (p < 0.01). The limb salvage rate was significantly improved by successful thrombolysis (63% at 2 years vs 31% if lysis failed; p < 0.01). The patient survival rate was high—89% 2 years after thrombolysis.Conclusions: Even with adjunctive therapy, vein graft thrombolysis is unlikely to yield durable patency overall. However, successful thrombolysis improves limb salvage rates and may be beneficial in patients without diabetes who have mature vein grafts but who do not have options for other autogenous revascularization procedures. (J Vasc Surg 1997;25:1023-32.)     

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. (J VASC SURG 1994;20:558-65.)     

Intraoperative color duplex scanning for infrainguinal vein grafts

We compared the findings of intraoperative color duplex scanning and completion arteriography in patients undergoing infrainguinal vein bypasses to identify hemodynamic abnormalities that could result in a predisposition to early or late graft failure. We reviewed the records of 72 patients who underwent 81 vein bypass graft procedures. Three intraoperative diagnostic methods were used. In 28 procedures (group I) both color duplex and completion arteriography were used, in 21 procedures (group II) only color duplex was used, and in 26 procedures (group III) only completion arteriography was used. Grafts were followed using a duplex surveillance protocol for a mean interval of 16.1 months. Nine grafts in group I showed an abnormality on the duplex scan but not on the completion arteriogram. Seven grafts had a peak systolic velocity (PSV) greater than 200 cm/sec and two had a PSV less than 45 cm/sec. These findings led to six immediate repairs, one early revision, and two late revisions. Arteriography demonstrated additional defects in two procedures but repairs were not performed. In group II duplex scans showed an abnormality in eight procedures (seven grafts with PSV 200 to 250 cm/sec and one graft with a retained valve) resulting in three immediate repairs and five late revisions. In the remaining 13 procedures in group II, duplex scans were normal and no revisions were required during follow-up. In group II defects were detected by arteriography in four procedures (>50% stenosis in three grafts and one arterial spasm) leading to three immediate repairs. In the remaining 22 studies arteriograms were interpreted as normal; however, seven of these grafts required late revisions. Our data suggest that grafts that appear normal on intraoperative duplex scans are not likely to develop a stenosis requiring revision. Intraoperative duplex ultrasound may be superior to completion arteriography.Presented at the Fourteenth Annual Meeting of the Southern California Vascular Surgical Society, September 15–17, 1995, La Jolla, Calif.     

Aneurysmal dilatation in saphenous vein bypass grafts

Three patients are reported who developed aneurysmal degeneration of a saphenous vein arterial bypass graft. All three had hypercholesterolemia and two had marked elevation of triglycerides. One bypass was for occlusive disease and two for popliteal aneurysm. There was a long lag, 3 to 7 years between graft implantation and aneurysmal degeneration. The pathology was similar for all three cases with lipid laden macrophages, loss of elastic lamina, and other atherosclerotic changes in the vein wall. While atheromatous changes and aneurysm formation in saphenous vein bypass grafts are rare, this may occur especially in patients with hypercholesterolemia and hypertriglyceridemia. Careful and prolonged follow-up plus vigorous management of the hyperlipidemic state is mandatory in these patients.     

Effect of preservation media on cellular apoptosis in autologous saphenous vein grafts procured for coronary revascularization

Purpose: Ischemic injury of the saphenous vein graft (SVG) during temporary storage prior to implantation in coronary bypass grafting (CABG) is believed to contribute to SVG thrombosis and stenosis. We aimed to show that; cellular apoptosis in endothelial and smooth muscle cells of the SVG is amplified by the short-term preservation, and that pyruvate-based preservation reduces the degree of cellular apoptosis as compared to other media. Methods: 5-cm SVG segments were taken from 14 patients undergoing CABG. Each 5-cm segment was then subdivided into five 1-cm units (totalling 70 units). For each patient, the first of the five subunits became the control and was immediately examined for apoptosis. These units did not undergo storage. The other four segments were stored at 20°C for 1-hour in one of the following solutions: Normal saline, Euro-Collins (EC), University of Wisconsin solution (UWS) or a 10mM pyruvate solution. Apoptotic cells were detected by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL assay) and the Student’s t-test was used for comparison. To minimize variability, each patient served as his/her own control. Results: Mean (SEM) number of TUNEL positive cells was similar in segments preserved with pyruvate when compared to Controls (4.00 ± 0.47% versus 4.03 ± 0.40%). When these compared by Student’s t-test, there was no significant difference in the number of apoptotic cells among 10/14 patients (71%). Pyruvate preserved segments had significantly less apoptosis (p < 0.05) in 10/14 patients (71%) when compared to normal saline, in 7/14 patients (50%) when compared to EC, and in 3/14 patients when compared to UWS. Conclusions: Procurement of SVGs is associated with a measurable degree of cellular apoptosis and cellular apoptosis is amplified by the short-term preservation. However, pyruvate preserved SVGs had less cell damage when compared to those preserved in other media and where similar to controls.     

Amyloidosis in saphenous vein aortocoronary bypass grafts

A patient in whom idiopathic amyloidosis of aortocoronary saphenous vein grafts was found at autopsy two years after myocardial revascularization due to coronary atherosclerosis is reported. Idiopathic generalized immunocyte derived amyloidosis extensively studied at autopsy was obviously present at the time of surgery although it remained unnoticed macroscopically in the inserted graft. It appears that simultaneously with arterialization further deposition and also significant redistribution of amyloid within the walls of the vein grafts additionally took place after their insertion. It seems interesting that in spite of the amyloidosis the grafts functioned well and were found patent two years after surgery.     

Cerebral revascularization using cadaveric vein grafts

BackgroundUse of cadaveric cryopreserved saphenous vein grafts (CSVGs) has been described for peripheral vascular and coronary revascularization. The aim of this study is to recognize CSVGs as a potential alternative to autologous conduits for extracranial-intracranial (EC-IC) bypass in patients without available or suitable saphenous vein graft or radial artery. We report the short-term patency rate of CSVGs in EC-IC bypass.MethodsWe present our preliminary experience in 10 patients using CSVG for cerebral revascularization. Data regarding operative indications, patient demographics, and bypass patency were collected.ResultsThe average age was 56 years old with equal sex distribution. The indications for the procedure were giant aneurysms in 7 patients, medically refractory vertebrobasilar ischemia in 2, and a skull base tumor in 1. ABO/Rh blood group compatible CSVG was used in each case. Postoperative angiography demonstrated patency in all cases. Quantitative magnetic resonance angiography was performed in 8 patients, demonstrating a mean bypass flow of 109 mL/min ± 19 mL/min (mean ± SE).ConclusionsUse of CSVG for EC-IC bypass has not previously been reported. In our series, the short-term patency rate was 100%, better than that found in cardiac and peripheral vascular series, possibly because of the higher flow in EC-IC bypasses. Our preliminary experience suggests that CSVGs may be an option in patients without available autologous conduits, although longer follow-up is needed to assess long-term patency.