The management of early in situ saphenous vein bypass occlusions

To determine the causes and optimum management of early in situ bypass occlusions, we reviewed our experience of 13 thromboses occurring within the first 30 postoperative days in 148 in situ saphenous vein reconstructions. All early thrombosed bypasses were performed for limb salvage, with 31% of bypasses to the popliteal level and 69% to infrapopliteal vessels. The median time to occlusion was 24 hours. All patients underwent reoperation. Graft failure was due to retained venous valves in 31% of the procedures, other technical problems in 38%, and inadequate outflow in 31%. Reoperative surgery was individualized. In grafts explored for thrombosis, the one-year graft patency rate was 46%, and the limb salvage rate was 54%. Graft patency did not appear to correlate with the presumed cause of initial graft occlusion. Our results indicate that an aggressive surgical approach is appropriate in early in situ graft thrombosis.

Neointimal hyperplasia occurring after carotid endarterectomy in a canine model: effect of endothelial cell seeding vs. perioperative aspirin

Neointimal hyperplasia of the arterial wall may occur after carotid endarterectomy. This proliferative lesion is a pathologic response of the injured arterial wall and may lead to progressive stenosis. We investigated the effect of endothelial cell seeding (ECS) or antiplatelet therapy with aspirin (ASA) on inhibition of this lesion in a canine model. Endarterectomies were performed in 160 carotid arteries; 46 endarterectomies were treated perioperatively with aspirin (325 mg per day), 34 were seeded with a high density (3 X 10(6)) of autogenous endothelial cells, and 80 were untreated control arteries. At selected time intervals, the patent arteries were perfusion-fixed and the cross-sectional area (measured in square millimeters) of neointimal hyperplasia was measured by means of digital planimetry. At 6 weeks, patency of the endarterectomized carotid artery was 88% in the ASA and ECS groups, in contrast to 35% in the control group (p less than 0.01). The cross-sectional area of neointimal hyperplasia was not significantly different in the ASA and the control groups at 6 weeks. However, the ECS group showed a marked reduction in neointimal hyperplasia at 6 weeks (p less than 0.01). This inhibition of neointimal hyperplasia after carotid endarterectomy by ECS may reflect accelerated luminal healing or a direct inhibition of smooth muscle cell proliferation in the injured arterial wall.

Beneficial effect of aspirin in maintaining the patency of small-caliber prosthetic grafts after thrombolysis with urokinase or tissue-type plasminogen activator

Despite successful thrombolysis of occluded prosthetic grafts, rethrombosis remains a problem. We investigated the efficacy of aspirin in maintaining patency of polytetrafluoroethylene grafts (3 mm X 3.5 cm) in canine femoral arteries after thrombolytic therapy. After induction of thrombosis, either tissue-type plasminogen activator (t-PA) or urokinase (UK) was infused just proximal to the thrombus (4000 U/min) until complete thrombolysis was achieved. Five of the 10 UK-treated dogs and five of the 10 t-PA-treated dogs received aspirin immediately after recanalization, and aspirin was continued (325 mg/day) for 4 weeks or until occlusion occurred. A systemic aspirin effect was confirmed by marked depression of serum thromboxane B2 and absent platelet aggregation. Only two of the 10 grafts in the aspirin-free group remained patent for 4 weeks. The remaining eight grafts had all reoccluded by 2 weeks. None of the 10 grafts in the aspirin-treated group reoccluded during the 4 weeks. This significantly improved patency (p less than .001) in the aspirin-treated group was observed equally in grafts treated with t-PA or UK. Thus aspirin is a potent agent in preventing rethrombosis after thrombolytic recanalization of prosthetic grafts.

Staged infrainguinal revascularization: initial prosthetic above-knee bypass followed by a distal vein bypass for recurrent ischemia. A valid concept for extending limb salvage?

Optimal infrainguinal revascularization should provide limb salvage for the longest duration of time. It is not known whether limb salvage is longer with an initial below-knee popliteal or tibial in situ saphenous vein graft or with staged bypasses; that is, an initial above-knee popliteal prosthetic bypass if feasible, followed by a more distal vein graft should the above-knee prosthetic graft fail. A retrospective review of 197 lower extremity vascular reconstructions performed since 1976 utilizing polytetrafluoroethylene (PTFE), umbilical vein, or in situ saphenous vein was completed. The data were analyzed for differences in limb salvage and prevention of limb threatening ischemia among three subgroups: above-knee prosthetic bypass, below-knee or tibial in situ saphenous vein bypass, and staged reconstructions (above-knee prosthetic bypass with subsequent in situ bypass). The groups were similar with respect to severity of limb threatening ischemia as indicated by mean preoperative ankle-brachial indices. Cumulative secondary limb salvage at 36 months was 73 percent for prosthetic grafts in the above-knee position, 78 percent for in situ saphenous vein grafts in the below-knee or tibial position, and 87 percent for staged reconstruction with an initial prosthetic graft to the above-knee position followed by a distal in situ vein bypass when the prosthetic graft fails.

Efficacy of tissue plasminogen activator and urokinase in a canine model of prosthetic graft thrombosis

Tissue plasminogen activator and urokinase were evaluated in a model of prosthetic graft thrombosis. In addition, the effects of thrombus age on lysability and the effect of thrombolytic agents on endothelium were examined. Polytef (polytetrafluoroethylene [PTFE]) grafts (3 mm X 3.5 cm) were placed in femoral arteries of dogs and graft thrombosis was induced. Grafts were treated with a local infusion of either urokinase or tissue plasminogen activator (4000 units/min) and the times for initial flow, complete thrombolysis, and anastomotic bleeding were noted. The luminal surfaces of the grafts and the proximal arterial segments were assayed for the production of thromboxane A2 and prostacyclin and examined with scanning electron microscopy. No difference in the ease of graft lysis was observed, but 50% of tissue plasminogen activator-treated vs 0% of urokinase treated grafts had extravasation of blood through the wall. Grafts treated with tissue plasminogen activator produced less thromboxane A2 and had less thrombus than those treated with urokinase. No differences between arteries exposed to either agent and control arteries were seen. Grafts treated 1,3,5, and 7 days after thrombosis were progressively more difficult to lyse. We conclude that tissue plasminogen activator is an effective thrombolytic agent, but has a potential for local bleeding complications. Grafts of PTFE are thrombogenic after lysis, but may be less so with tissue plasminogen activator than with urokinase. No effect on arterial endothelium was seen, and our studies confirm the clinical impression that older thrombi are more difficult to lyse.

Retroperitoneal approach to high-risk abdominal aortic aneurysms

During a 14-month period we used a left-flank, retroperitoneal, retrorenal approach in 23 high-risk patients with abdominal aortic aneurysm (AAA). Fourteen patients underwent suprarenal/celiac cross clamp for juxtarenal/suprarenal AAA and/or associated occlusive disease. Other indications for this approach included diminished cardiac and/or pulmonary reserve, previous extensive abdominal surgery, obesity, and inflammatory AAA. There was only one death (4%) in this high-risk group and minimal operative morbidity. The flexibility afforded by this approach for high aortic exposure allowed expeditious proximal anastomoses with minimal postoperative renal dysfunction. Pulmonary complications, ileus, and pain were reduced and patient mobilization was rapid despite the complex nature of the operative procedures. We believe that this approach offers significant advantages for all cases of AAA but particularly for anatomically complex lesions and medically high-risk patients.

The natural history of endothelial structure and function in arterialized vein grafts

When the saphenous vein is used in the in situ position for arterial bypass surgery, it is associated with more optimal preservation of the endothelial lining and with improved graft patency compared with reversed vein grafts. However, it is not clear whether preservation of endothelial integrity persists after arterialization. The goal of this study was to establish whether preservation of the endothelium before arterialization is a critical factor in the development of late functional and morphologic abnormalities of autogenous vein grafts. Paired reversed and in situ vein grafts were created in 75 mongrel dogs. Veins to be used in the reversed position were excised and stored in either heparinized whole blood at 37 degrees C or saline solution at 4 degrees C. Veins were studied before and after arterialization. The veins were arterialized by anastomosis to the carotid artery and excised at intervals of 1 day to 12 weeks for studies of the luminal production of prostacyclin and thromboxane A2 in addition to luminal morphology. Before arterialization, normothermic whole blood preserved biochemical function of the endothelium significantly better than hypothermic saline solution, but not as well as the in situ vein procedure. Soon after arterialization, all three vein grafts showed significant functional and morphologic abnormalities consistent with injury of the vein graft. Morphologic healing of the endothelial monolayer progressed slowly back to normal; however, the biochemical capacity of the vein graft never matched that of the prearterialized vein, nor that of normal host arteries. Regardless of surgical technique, all vein grafts exhibited a period of abnormal structure and function, which exposed them to the risk of thrombogenesis. This period of potential leukocyte or platelet interaction with the vein wall could lead to release phenomena as well as proliferative changes in the vessel wall.

In situ saphenous vein bypass grafts for limb salvage. A current fad or a viable alternative to reversed vein bypass grafts?

Revascularization of the lower extremity using the in situ saphenous vein bypass graft has resurfaced as a clinical alternative to reversal of the saphenous vein. Early patency rates have been excellent, however, concern has been raised about the durability of the in situ technique. Our total experience with this technique has been reviewed to evaluate its effectiveness on a teaching vascular service. Seventy-six limbs in 71 patients were revascularized using the in situ technique. The distal anastomosis was created at the below-the-knee popliteal level in 26 limbs and at the infrapopliteal level in 50 limbs. Operative assessment of the vein quality showed 42 percent to be phlebitic or less than 4 mm in diameter. Hospital mortality was 0 and late mortality was 8 percent. Cumulative life table analysis showed the graft patency rate to be 89 percent 1 month postoperatively, 82 percent at 1 year, 77 percent at 2 years, and 72 percent up to 4 year postoperatively. Patency was independent of runoff to the pedal arch and the level of the distal anastomosis. Limb salvage at 4 years was 83 percent for distal popliteal grafts and 79 percent for infrapopliteal reconstructions. Our results indicate that the long-term durability of the in situ saphenous vein graft is excellent despite suboptimal veins and poor runoff. When performed properly, it is the preferred technique for arterial reconstruction below the knee joint.

Prolonged disruption of plasma beta-endorphin dynamics following surgery

The purpose of the present study was to examine the effects of surgery on plasma beta-endorphin dynamics. Plasma beta-endorphin levels were measured by liquid chromatography/radioimmunoassay in seven patients undergoing elective surgery. Blood samples were obtained every 4 hr for two 24-hr periods: one beginning 48 hr before surgery and the other beginning 48 hr after surgery. Computer analysis of beta-endorphin levels as a function of clock time demonstrated a true circadian rhythm preoperatively with a mean of 28.0 +/- 5.9 pg/ml. In the postoperative period mean beta-endorphin levels were significantly elevated (85.6 +/- 20.7 pg/ml, P less than 0.005). Surgical procedures caused significant phase shifting in the grouped mean circadian rhythm of plasma beta-endorphin (mean = 2.4 hr). When the data was analyzed individually, plasma circadian rhythms were found to be totally abolished in the three patients with the longest operative times (mean = 3.8 hr) and significantly displaced in time in the remaining four patients. These prolonged alterations in plasma endogenous opioid peptide levels following surgery have not been previously reported, and should be considered in the management of the postsurgical patient.

Beta-endorphin, cortisol and postoperative delirium: a preliminary report

A transient delirium, including hallucinations and disorientation, occurred at some time during a 48 to 72 hr postoperative period in patients recovering from elective surgery in an intensive care unit. The occurrence of delirium in these patients was associated with a significant and unusually prolonged postoperative increase in circulating levels of beta-endorphin (B-endorphin) and cortisol, and a total disruption of normal plasma circadian rhythms of B-endorphin and cortisol. Postoperative mean 24-hr plasma levels of B-endorphin and cortisol were not significantly different from preoperative baseline levels in those patients who did not exhibit post-surgical delirium. Circadian rhythms of B-endorphin and cortisol in the non-delirious patients also remained normal following surgery, although peak plasma concentrations were significantly phase-shifted to later in the day. A disruption in circadian rhythms of the endogenous opiate/hypothalamic-pituitary-adrenal axis may represent an important component of post-operative psychological changes that are frequently observed in the intensive care unit setting.

Luminal release of prostacyclin and thromboxane A2 by arteries distal to small-caliber prosthetic grafts

Myointimal hyperplasia distal to prosthetic grafts may be due to a local imbalance of prostacyclin and thromboxane A2 that exaggerates platelet adherence. This study evaluated prostacyclin and thromboxane A2 production by arteries distal to prosthetic grafts. In 12 dogs, control segments of both iliac arteries were excised and a 5 cm segment of polytetrafluoroethylene was grafted end to end. One iliac artery was circumferentially dissected from the distal anastomosis to the inguinal ligament. The contralateral artery was not dissected. Of the 24 grafts, 19 remained patent and the arteries distal to these grafts were studied. After excision, each artery was analyzed for its ability to produce prostacyclin and thromboxane A2. Our data indicate that the luminal surface of a normal artery spontaneously produces both prostacyclin and thromboxane A2 and that the arterial wall distal to a prosthetic graft produces increased levels of these arachidonic acid metabolites. However, only those arteries not surgically dissected maintain a normal balance of prostacyclin and thromboxane A2. The dissected artery may thus be more susceptible to platelet interaction and myointimal hyperplasia.

Functional Injury of Vein Graft Endothelium

The cause of endothelial injury during vein harvesting and preservation is complex. Hypothermia is thought necessary to preserve cell viability but has been implicated in morphologic injury to the endothelium. This study explored the effect of temperature on preserving endothelial function using prostacyclin production as a metabolic marker. Canine veins were atraumatically excised and matched segments were stored at three temperatures using either nutrient medium or heparinized saline. After storage, endogenous production of prostacyclin by the luminal surface of each vein was collected in a closed perfusion system at 37 degrees C and assayed by radioimmunoassay. Optimal prostacyclin production was observed in veins stored in tissue culture medium at normothermia. Preservation of normal endothelial function may require revision of traditional vein graft-harvesting techniques.

Favorable balance of prostacyclin and thromboxane A2 improves early patency of human in situ vein grafts

Graft thrombosis soon after reconstruction remains a major obstacle to the use of reversed vein grafts in infrapopliteal reconstruction. Our clinical experience with in situ vein grafts corroborates Leather's results by demonstrating an overall graft patency of 95% below the knee at 1 year and 94% in the infrapopliteal group. It has been postulated that this improved early patency rate of in situ vein grafts is the result of more optimal preservation of the endothelium of the vein graft. To investigate this hypothesis, human saphenous veins were handled by an in situ and a reversed technique. The intact vein segments were then tested for luminal production of prostacyclin and thromboxane A2 and fixed for scanning electron microscopic analysis of the surface morphology. This study demonstrated that endothelial cell prostacyclin release is enhanced in human in situ vein segments but not in reversed vein segments. In addition, luminal production of thromboxane A2 is significantly greater in the reversed than in the in situ vein segments. These findings are associated with marked endothelial structural damage in the reversed veins and minimal endothelial disruption in the in situ veins. Therefore the ratio of the antiaggregatory vasodilator prostacyclin to the proaggregatory vasoconstrictor thromboxane A2 is significantly more favorable for the in situ vein segment than for the reversed vein segment. The observed excellent early patency of the in situ vein grafts in our poor-risk patient population may in part be the result of this favorable balance of prostacyclin and thromboxane A2 and the more optimally preserved endothelial morphology.

Combined operative angiodilation and arterial reconstruction for limb salvage

Fifteen high-risk patients with threatened limb loss underwent combined operative iliac angiodilation and infrainguinal vascular reconstruction for iliac and femoropopliteal occlusive disease. The patients were poor candidates for combined surgical inflow and outflow reconstruction because of associated cardiopulmonary disease. The mean systolic pressure gradient across the iliac stenosis was 34 +/- 5 mm Hg. Iliac artery angiodilation was accomplished intraoperatively and reduced all gradients to zero. Stenoses in the distal portion of the deep femoral artery were endarterectomized in nine patients, and six cross-femoral and six distal popliteal or tibial grafts were constructed. Life-table analysis at 36 months showed iliac patency in 86% of cases and successful distal reconstruction in 76%. Our limb salvage rate of 86% suggests that combined intraoperative angiodilation by the angiographer and arterial reconstruction by the vascular surgeon may provide effective therapy for high-risk patients.

Direct venous surgery for venous valvular insufficiency of the lower extremity

Seven patients had severe deep venous insufficiency and recurrent ulceration in eight lower extremities. All incompetent perforating veins had been previously ligated. All limbs were evaluated by dynamic venous pressure measurements. The venous pressure reduction with exercise was recorded, as well as the recovery time. The most accurate indicator of venous valvular incompetence was a short postexercise recovery time. Abnormal hemodynamic findings were correlated with ascending and descending venographic findings. Based on these anatomic and pathophysiologic abnormalities, patients underwent valvular transposition, superficial femoral vein valvuloplasty, or superficial femoral vein ligation. Immediate postoperative recovery time (mean +/- SEM) was improved to 34.5 +/- 18.3 s from 7.9 +/- 2.9 s preoperatively. Postoperative venography demonstrated patency of all anastomoses and absence of reflux into previously incompetent venous systems. All limbs were symptomatically improved after operation, and no venous thrombosis or pulmonary emboll developed. Persistent ulceration, however, continued in one limb.

Distal in situ saphenous vein grafts for limb salvage. Increased operative blood flow and postoperative patency

Early failure remains a major obstacle to successful distal bypass surgery using vein grafts for limb salvage. Thirty distal bypass graft procedures were performed for limb salvage using the in situ technique. Grafts were anastomosed to the distal popliteal artery in 13 patients and to the infrapopliteal artery in 17 patients. Sixteen patients had inadequate saphenous veins for reversed vein grafts. The mean blood flow measured through these grafts (n = 20) was 164 +/- 22 ml/min and increased to 278 +/- 31 ml/min after administration of 30 mg of papaverine. All grafts were patent at the time of hospital discharge and patients were followed for 1 to 28 months. Life table analysis of the 30 procedures shows a patency of 100 percent at 18 months follow-up. One graft subsequently failed at 22 months. Long-term limb salvage was achieved in 100 percent of the patients in this series. The excellent blood flow through these grafts suggests that the in situ vein graft technique may be more favorable for arterial reconstruction than the reversed vein graft technique. Our preliminary data confirm the observations of Leather et al [3,4], that the rates of vein utilization and graft patency are higher with the in situ technique.

Renal failure following abdominal aortic reconstruction

Renal failure in aortic surgery is frequently due to the additive effects of multiple subthreshold insults that progressively decrease renal reserve. Prevention of renal failure requires a high index of suspicion concerning the clinical setting in which renal injury may occur. If cardiac hemodynamics and arterial pressure are maintained at optimal levels, especially during periods of maximum hemodynamic stress, ischemic renal injury can be minimized. This requires aggressive monitoring of cardiac hemodynamics using a Swan-Ganz (thermodilution) catheter for measurement of pulmonary artery wedge pressure and cardiac output. Prompt recognition of hemodynamic instability allows rapid intervention to correct the renal ischemia before irreversible renal injury can occur.

Lethal complications associated with nonrestrictive treatment of abdominal aortic aneurysms

Five high-risk patients received nonresective treatment of abdominal aortic aneurysms (AAAs). This treatment included ligation of the iliac arteries to induce acute thrombosis of AAA and a simultaneous axillobifemoral bypass for restoration of arterial flow to the lower extremities. Of these five patients, lethal complications associated with this procedure developed in four. The complications included rupture, infection of the thrombotic aortic aneurysm, visceral ischemia, and consumptive coagulopathy. This high incidence of lethal complications and the unacceptably high patient mortality in these five patients indicates extreme precaution in the application of nonresective treatment for AAA.

Bleeding esophageal varices: treatment with vasopressin, transhepatic embolization and selective splenorenal shunting

The fate of 359 consecutive alcoholic cirrhotic male patients with bleeding esophageal varices was determined through chart review and personal interview. Three historical periods (1966-70; 1971-75; 1976-80) were defined based on availability of different therapeutic modalities. Management of acutely bleeding varices by conservative, nonsurgical means, including embolization, was preferable to emergency surgery when considering 30-day mortality rates. Percutaneous transhepatic embolization of esophagogastric varices significantly improved the rate of control of hemorrhage and 30-day survival over previously employed nonsurgical methods. The combination of nonsurgical management of acute variceal hemorrhage followed by selective distal splenorenal shunting resulted in maximum salvage of the alcoholic cirrhotic patient.

Prevention of renal insufficiency after abdominal aortic aneurysm resection by optimal volume loading

A retrospective case review of 34 men was undertaken to evaluate the relationship between preoperative volume loading and renal function before, during, and after abdominal aortic aneurysm surgery. Volume expansion was guided by either central venous pressure (CVP) in 12 patients or pulmonary artery wedge pressure (PAWP) measurements in 22 patients. Statistically significant differences (P less than .05) were noted between the two groups where greater preoperative volume loading and urine output were associated with lower postoperative serum creatinine and renal function indices in the PAWP group. The age range, vascular risk factors, aneurysm size, and preoperative renal function were similar. The data indicate that (1) PAWP is a more accurate monitor for volume expansion than CVP and (2) when volume replacement is optimal, abdominal aortic aneurysm surgery is not associated with postoperative renal insufficiency.

Atherosclerotic aneurysms of the superficial femoral artery: a literature review and report of six additional cases

Six patients with seven superficial femoral artery aneurysms are described, and additional cases in the literature are reviewed. Superficial femoral artery aneurysms are found in elderly patients with advanced atherosclerosis. These patients usually present with signs and symptoms of a high mass, often with local expansion and rupture. Proximal and distal ligation with vein bypass grafting was, for the authors, a satisfactory method of treatment. Patients with this lesion should be screened for possible abdominal aortic aneurysms, present in 33% of the authors' patients, and for other peripheral aneurysms, present in 50% of the authors' patients. Superficial femoral artery aneurysms should be surgically repaired, because when untreated, they tend to rupture and occasionally serve as a source of emboli.

Computed tomographic angiography

Computed tomographic angiography performed by the intravenous administration of contrast medium was evaluated in 86 vascular patients. This experience demonstrates a new approach to the evaluation of patients with symptomatic aortic aneurysms, in whom computed tomographic angiography will aid in evaluating the need for emergency surgery. Nonoperative patients are serially evaluated by computed tomographic angiography to detect significant changes in the geometric configuration of their aneurysms. Computed tomographic angiography was beneficial in the evaluation of the patency of vascular reconstructive procedures such as femoropopliteal bypass, aortoiliac bypass and application of a vena caval device. More clinical experience and possibly a rapid sequence technique are needed to evaluate patients with portasystemic shunts.

Bleeding esophageal varices: treatment by embolization and shunting

An assessment was made of the treatment of 120 consecutive, alcoholic, cirrhotic patients with bleeding esophageal varices. Percutaneous, transhepatic embolization of the esophagaogastric varices resulted in control of the hemorrhage and this approach was more effective than were the non-surgical methods used. Management of acute variceal bleeding by conservative non-surgical means, including embolization, appears preferable to emergency portal-systemic shunts. The combination of non-surgical control of the acute variceal hemorrhage plus subsequent selective distal splenorenal shunting resulted in minimal encephalopathy and the most effective treatment.