Recessed elliptical-centric view-ordering for contrast-enhanced 3D MR angiography of the carotid arteries

Fast arterial-venous transit in the carotid arteries requires accurate, reliable timing of the acquisition to the bolus transit to maximize arterial signal and minimize venous artifacts. The rising edge of the bolus is not utilized in conventional elliptical-centric view-ordering because the critical k-space center must be acquired with full arterial enhancement. In this study, a recessed elliptical-centric view-ordering scheme is introduced in which the k-space center is acquired a few seconds following scan initiation. The recessed view-ordering is shown to be more robust to timing errors than the conventional scheme in a study of 37 patients.

Cross-sectional pattern of collateral vessels in patients with superficial femoral artery occlusion

RATIONALE AND OBJECTIVES

The purpose of this study was to identify the cross-sectional location of collateral vessels in patients with peripheral vascular disease on three-dimensional magnetic resonance angiograms (3D MRAs) to suggest sites for intravascular or transcutaneous angiogenesis gene delivery in the lower extremity.

METHODS

The axial locations were measured and categorized by tissue compartments, as well as by radial coordinates with respect to the femur.

RESULTS

Collateral vessels in the thigh were identified in 24 of 93 consecutive patients who underwent peripheral 3D MRA. Ninety-one percent (99/109) of the observed collaterals were located near the adductor canal level of the thigh, with 78% (31/46) of these collaterals located in the fat in or surrounding the posterior muscle.

CONCLUSIONS

The majority of collateral vessels in the thigh are located in the fat or muscle within the posterior compartment near the femur at the level of the adductor canal.

Thrombolysis for native arterial occlusions of the lower extremities: clinical outcome and cost

INTRODUCTION

Intra-arterial thrombolysis is commonly used as the initial treatment of acute or subacute lower extremity ischemia.

METHODS

To evaluate the efficacy and cost of thrombolysis, we retrospectively analyzed 100 consecutive cases (87 patients) in which intra-arterial lysis (urokinase) was used as the initial treatment for native arterial lower extremity occlusive disease. The mean age of patients was 67 years, 57% of the patients were male, and preexisting peripheral vascular disease was present in 74%. Presenting symptoms were limb-threatening ischemia (53%) and claudication (47%). Acute symptoms (< 2 weeks' duration) were present in 48%.

RESULTS

The 30-day morbidity rate was 31%, and four patients died. Complications were significant bleeding (23%), ischemic stroke (1%), and renal failure with (2%) and without (2%) dialysis. Concomitant angioplasty was performed in 63%. Complete or significant lysis as demonstrated with angiography was achieved in 75% of iliac, 58% of femoropopliteal, and 41% of crural vessels (P <.001). Within 30 days of lysis, 9% of patients underwent major amputation and 20% surgical revascularization (in 3 patients the extent of revascularization was lessened by the lytic therapy). Amputation-free survival was 83% and 75% at 6 months and 2 years, respectively. Relief of ischemia (defined as relief of claudication or limb salvage without major surgical intervention) was achieved in only 70% and 43% of patients at 30 days and 2 years, respectively (Kaplan-Meier analysis; mean follow-up, 31 months). Patients with aortoiliac disease had significantly better outcomes than those with infrainguinal disease (P =.03). Duration or type of presenting symptoms did not predict outcome. The cost of the initial hospitalization per patient for thrombolysis was $18,490.

CONCLUSION

Thrombolysis can be as or more costly than surgery and is associated with a suboptimal outcome in a significant number of patients. These data lead us to caution against a uniform policy of initial thrombolysis for patients who present with lower extremity ischemia.

Contrast-enhanced peripheral MR angiography from the abdominal aorta to the pedal arteries: combined dynamic two-dimensional and bolus-chase three-dimensional acquisitions

Wang Y, Winchester PA, Khilnani NM, et al. Contrast-enhanced peripheral MR angiography from the abdominal aorta to the pedal arteries: Combined dynamic two-dimensional and bolus-chase three-dimensional acquisitions. Invest Radiol 2001;36:170-177.

RATIONALE AND OBJECTIVES

To obtain reliable contrast-enhanced peripheral MR angiography for imaging peripheral vascular disease from the abdominal aorta to the pedal arteries.

METHODS

A protocol consisting of contrast-enhanced, dynamic two-dimensional (2D) acquisition at the feet and calf and bolus-chase three-dimensional (3D) acquisition from the abdominal aorta to the calf was developed and applied in patients with peripheral vascular disease. The performance of this integrated protocol was assessed in 89 consecutive patients.

RESULTS

The bolus-chase 3D acquisition was of diagnostic quality in 100% of the acquisitions in the abdomen, 96% in the thigh, and 43% in the calf. The poor quality of the calf acquisitions was due to insufficient spatial resolution, poor arterial signal, and venous contamination. Diagnostic-quality images were obtained in 100% of the dynamic 2D acquisitions of the calf and 98% of the feet.

CONCLUSIONS

The combined dynamic 2D and bolus-chase 3D contrast-enhanced MR angiography technique provides diagnostic images of the entire lower extremity.

Two decades of abdominal aortic aneurysm repair: have we made any progress?

PURPOSE

Over the past 20 years, there have been numerous advances in our ability to detect and to treat abdominal aortic aneurysms (AAAs). We hypothesized that these advances would lead to (1) an increase in the rate of elective repair and a decrease in the incidence of ruptured AAA (rAAA) and (2) a decrease in operative deaths for both elective AAA (eAAA) and rAAA.

METHODS

To test these hypotheses, we investigated the incidence and outcomes of eAAA and rAAA surgery between 1979 and 1997, using the National Hospital Discharge Survey. This data set is a randomized, stratified sample representing discharges from the nation's acute care, nonfederally funded hospitals. Codes from the International Classification of Diseases, Ninth Revision were used to identify our study population.

RESULTS

Over the past 19 years, there has been no change in the incidence rate of eAAA repair (range, 44.1-77.9 per 100,000). Moreover, the incidence of rAAAs presenting to the nation's hospitals has not changed (range, 6.6-16.3 per 100,000). There has been no consistent improvement over time in operative deaths associated with either eAAA or rAAA repair (average rates over the study period: eAAA, 5.6%; rAAA, 45.7%). Significant predictors of death from eAAA in patients included an age older than 80 years, African American race, congestive heart failure (CHF), and diabetes (P<.0001 for all). Significant predictors of death from rAAA in patients included age older than 70 years, African American race, female sex, renal failure, and a hospital bed size more than 500 (P<.05 for all).

CONCLUSION

On a national level, over the past 19 years, our ability to identify and to treat patients with AAA has not improved. Advances in technology and critical care have not affected outcome. Regionalization of care, screening of high-risk populations, and endovascular repair are strategies that might allow further improvement in the outcome of patients with aneurysmal disease.

The cost-effectiveness of repairing ruptured abdominal aortic aneurysms

BACKGROUND

Although advances in technology have reduced the operative risk of elective abdominal aortic aneurysm (AAA) repair, the surgical repair of ruptured AAAs is associated with a much poorer prognosis and a higher cost. Accordingly, it has been suggested that patients with predictably high rates of morbidity and mortality from ruptured AAA may not benefit from surgical intervention.

METHODS AND RESULTS

A cost-effectiveness analysis was performed with the use of a Markov decision-analytic model to compute long-term survival in quality-adjusted life years and lifetime costs for a hypothetical cohort of patients with ruptured AAAs managed with either a strategy of open surgical repair or no intervention. Probability estimates for the various outcomes were based on a review of the literature. Average costs of (1) the immediate hospitalization ($28,356) and (2) complications resulting from the procedure were based on the average use of resources as reported in the literature and from a hospital's cost accounting system. Our measure of outcome was the incremental cost-effectiveness ratio. For our base-case analysis, the repair of ruptured AAAs was cost-effective with an incremental cost-effectiveness ratio of $10,754. (Society is usually willing to pay for interventions with cost-effectiveness ratios of less than $60,000; for example, the costeffectiveness ratios for coronary artery bypass grafting and dialysis are $9500 and $54,400, respectively.) In sensitivity analyses, the cost-effectiveness of repairing ruptured AAAs was influenced only by alterations in the operative mortality. If the operative mortality exceeded 88%, repair of ruptured AAAs was no longer cost-effective. As an independent variable, increasing age had no substantial impact on the cost-effectiveness, although it is reported to be associated with increased operative mortality. It was necessary that the patient's cost of the initial hospitalization for ruptured AAA exceed $195,000 before repairing ruptured AAAs was no longer cost-effective.

CONCLUSIONS

Our analysis suggests that despite the high cost and poor outcomes, the surgical repair of ruptured AAAs is still cost-effective when compared with no intervention. The cost of repairing ruptured AAAs falls within society's acceptable limits and therefore should not be a consideration in the management of patients with AAAs.

Is carotid endarterectomy cost-effective in symptomatic patients with moderate (50% to 69%) stenosis?

OBJECTIVE

Recently published data from the North American Carotid Endarterectomy Trial revealed a benefit for carotid endarterectomy (CEA) in symptomatic patients with moderate (50% to 69%) carotid stenosis. This benefit was significant but small (absolute stroke risk reduction at 5 years, 6.5%; 22.2% vs 15.7%), and thus, the authors of this study were tentative in the recommendation of operation for these patients. To better elucidate whether CEA in symptomatic patients with moderate carotid stenosis is a proper allocation of societal resources, we examined the cost-effectiveness of this intervention.

METHODS

A decision-analytic Markov process model was constructed to determine the cost-effectiveness of CEA versus medical treatment for a hypothetical cohort of 66-year-old patients with moderate carotid stenosis. This model allowed the comparison of not only the immediate hospitalization but also the lifetime costs and benefits of these two strategies. Our measure of outcome was the cost-effectiveness ratio (CER), defined as the incremental lifetime cost per quality-adjusted life year saved. We assumed an operative stroke and death rate of 6.6% and a declining risk of ipsilateral stroke after the ischemic event with medical treatment (first year, 9.3%; second year, 4%; subsequent years, 3%). The hospitalization cost of CEA ($6,420) and the annual costs of major stroke ($26,880), minor stroke ($798), and aspirin therapy ($63) were estimated from a hospital cost accounting system and the literature.

RESULTS

CEA for moderate carotid stenosis increased the survival rate by 0.13 quality-adjusted life years as compared with medical treatment at an additional lifetime cost of $580. Thus, CEA was cost-effective with a CER of $4,462. Society is usually willing to pay for interventions with CERs of less than $60,000 (eg, CERs for coronary artery bypass grafting at $9,100 and for dialysis at $53,000). CEA was not cost-effective if the perioperative risk was greater than 11.3%, if the ipsilateral stroke rate associated with medical treatment at 1 year was reduced to 4.3%, if the age of the patient exceeded 83 years, or if the cost of CEA exceeded $13,200.

CONCLUSION

CEA in patients with symptomatic moderate carotid stenosis of 50% to 69% is cost-effective. Perioperative risk of stroke or death, medical and surgical stroke risk, cost of CEA, and age are important determinants of the cost-effectiveness of this intervention.

The expression of TGF-beta receptors in human atherosclerosis: evidence for acquired resistance to apoptosis due to receptor imbalance

The degree of cellularity in vascular lesions is determined by the balance between the migration and proliferation of cells relative to their rate of egress and apoptosis. Transforming growth factor-beta(1) can act as a potent antiproliferative and apoptotic factor for proliferating vascular cells. Our laboratory has previously identified cells cultured from human vascular lesions that are resistant to the antiproliferative effect of TGF-beta(1) due to an acquired mutation in the Type II receptor for TGF-beta(1). In the present studies, the expression of the Type I and II receptors in coronary and carotid atherosclerotic lesions was analysed by immunostaining, RT-PCR, and in situ RT-PCR. Levels of the Type I and Type II receptors varied widely within lesions, with the highest levels in the fibrous cap and at discrete foci within the lesion. Regions of smooth muscle-like cells (SMC) were commonly found that were Type I positive but Type II receptor negative. In 43 cell lines cultured from 126 human lesions, 84% of the lesion-derived cell (LDC) cultures exhibited functional resistance to the antiproliferative effect of TGF-beta(1). This resistance was conferred against TGF-beta(1), TGF-beta(2), and TGF- beta(3), but not interferon-gamma or mimosine. While normal SMC exhibited a four-fold increase in the rate of apoptosis after TGF- beta(1) treatment, most LDC were resistant to apoptosis in response to TGF-beta(1). Resistant cells exhibited selective loss of Type II receptor expression, and retroviral transfection of Type II receptor cDNA partially corrected the functional deficit. Thus, resistance to apoptosis may lead to the slow proliferation of resistant cell subsets, thereby contributing to the progression of atherosclerotic and restenotic lesions.

The cost-effectiveness of endovascular repair versus open surgical repair of abdominal aortic aneurysms: A decision analysis model

PURPOSE

Endovascular repair (EVR) is a less-invasive method for the treatment of abdominal aortic aneurysms (AAAs) as compared with open surgical repair (OSR). The potential benefits of EVR include increased patient acceptance, less resource utilization, and cost savings. This study was designed to determine whether the EVR of AAAs is a cost-effective alternative to OSR.

METHODS

A cost-effectiveness analysis was performed using a Markov decision analysis model to compute long-term survival rates in quality-adjusted life years and lifetime costs for a hypothetical cohort of patients who underwent either OSR or EVR. Probability estimates of the different outcomes of the two alternative strategies were made on the basis of a review of the literature. The average costs of (1) the immediate hospitalization ($16,016 for OSR, $20,083 for EVR), (2) the complications that resulted from each procedure, (3) the subsequent interventions, and (4) the surveillance protocol were determined on the basis of average resource utilization as reported in the literature and from our hospital's cost accounting system. Our measure of outcome was the cost-effectiveness ratio.

RESULTS

For our base-case analysis (70-year-old men with 5-cm AAAs), EVR was cost-effective with a cost-effectiveness ratio of $22,826-society usually is willing to pay for interventions with cost-effectiveness ratios of less than $60,000 (eg, cost-effectiveness ratios for coronary artery bypass grafting and dialysis are $9500 and $54,400, respectively). This conclusion did not vary significantly with increases in procedural costs for EVR (ie, if the cost of the endograft increased from $8000 to $12,000, EVR remained cost-effective with a cost-effectiveness ratio of $32,881). The cost-effectiveness of EVR was critically dependent on EVR producing a large reduction in the combined mortality and long-term morbidity rate (stroke, dialysis-dependent renal failure, major amputation, myocardial infarction) as compared with OSR (ie, a reduction in the combined mortality and long-term morbidity rate of OSR from 9.1% to 4.7% made EVR no longer cost-effective).

CONCLUSION

Despite the high cost of new technology and the need for close postoperative surveillance, EVR is a cost-effective alternative for the repair of AAAs. However, the cost-effectiveness of this new technology is critically dependent on its potential to reduce morbidity and mortality rates as compared with OSR. EVR may not be cost-effective in medical centers where OSR can be performed with low risk.

Is thrombolysis of lower extremity acute arterial occlusion cost-effective?

BACKGROUND

The TOPAS (thrombolysis or peripheral artery surgery) trial randomized 544 patients with acute lower extremity ischemia to either surgery or thrombolysis. Although statistically equivalent 1-year morbidities and mortalities were demonstrated, the comparative cost-effectiveness of these two interventions has not been explored.

MATERIALS AND METHODS

We constructed a Markov decision-analytic model to determine the cost-effectiveness of thrombolysis relative to surgery for a hypothetical cohort of patients with acute lower extremity arterial occlusion. Our measure of outcome was the cost-effectiveness ratio (CER), defined as the incremental lifetime cost per quality-adjusted life year gained. Estimates of 1-year outcomes were based on the TOPAS trial: mortality (lysis, 20%; surgery, 17%), amputation (lysis, 15%; surgery, 13%), the number of additional interventions required following the initial procedure (lysis, 544; surgery, 439). Procedural costs were estimated from the cost accounting system at the New York Presbyterian Hospital as well as from the literature.

RESULTS

Operative intervention for acute lower extremity arterial occlusion extended life and was less costly compared to thrombolysis. The projected life expectancy for patients who underwent initial surgery was 5.04 years versus 4.75 years for initial thrombolysis. The lifetime costs were $57,429 for surgery versus $dollar;76,326 for thrombolysis. In performing sensitivity analyses, a threshold CER of $60,000 was considered what society would pay for accepted medical interventions. Thrombolysis became cost-effective if the 1-year mortality rate for lysis was lowered from 20 to 10.7%, if the amputation rate for lysis diminished from 15 to 3.9%, or if the 1-year cost of lysis could be reduced to a level below $13,000.

CONCLUSIONS

Initial surgery provides the most efficient and economical utilization of resources for acute lower extremity arterial occlusion. The high cost of thrombolysis is related to the expense of the lytic agents, the need for subsequent interventions in patients treated with initial lysis, and the long-term costs of amputation in patients who fail lytic therapy.

Type B aortic dissection and thoracoabdominal aneurysm formation after endoluminal stent repair of abdominal aortic aneurysm

Endoluminal stent graft repair of abdominal and thoracic aortic aneurysms is being performed in increasing numbers. The long-term benefits of this technology remain to be seen. Reports have begun to appear regarding complications of stent graft application, such as renal failure, intestinal infarction, distal embolization, and rupture. Many of these complications have been associated with a fatal outcome. We describe a case of acute, retrograde, type B aortic dissection after application of an endoluminal stent graft for an asymptomatic infrarenal abdominal aortic aneurysm. An extent I thoracoabdominal aortic aneurysm subsequently developed and was successfully repaired. Aggressive evaluation of new back pain after such a procedure is warranted. Further analysis of the short-term complications and long-term outcome of this new technology is indicated before universal application can be recommended.

Comparison of two-dimensional MR digital subtraction angiography of the lower extremity with x-ray angiography

PURPOSE

To perform a preliminary evaluation of the diagnostic accuracy of contrast-enhanced, two-dimensional (2D) magnetic resonance (MR) digital subtraction angiography (DSA) of the lower extremity by comparison with x-ray angiography (XRA).

MATERIALS AND METHODS

Forty lower extremities in 22 patients were imaged at multiple levels with both XRA and 2D MR DSA. Images were retrospectively analyzed by three radiologists in a randomized blinded manner. Seventeen vascular segments were graded as an insignificant lesion, a significant lesion, or as an occlusion. With the use of segments well depicted with XRA as the gold standard, the sensitivity, specificity, and accuracy of 2D MR DSA, as compared with XRA, were evaluated. The McNemar-Stuart-Maxwell test was performed to determine the significance of any differences found.

RESULTS

Three hundred eighty-three arterial segments were evaluated with both techniques. Three hundred one segments were well depicted with XRA. There was no significant difference between 2D MR DSA and XRA for assessing the degree of occlusive disease in these 301 segments (.25 < P < .5). The sensitivity, specificity, and diagnostic accuracy of 2D MR DSA were found to be 90%, 98%, and 93%, respectively.

CONCLUSION

Two-dimensional MR DSA is an accurate method for assessing arterial lesions in the lower extremity.

Distal lower extremity arteries: evaluation with two-dimensional MR digital subtraction angiography

PURPOSE

To test the hypothesis that magnetic resonance (MR) digital subtraction angiography is superior to two-dimensional time-of-flight (TOF) MR angiography for demonstration of patent arteries in the distal lower extremity.

MATERIALS AND METHODS

Thirty-seven lower extremities in 23 consecutive patients were imaged with two-dimensional TOF MR angiography and two-dimensional MR digital subtraction angiography. Images were interpreted in a randomized and blinded manner. Each lower extremity was subdivided into seven potential arterial segments. The number of digital arteries visualized was also determined. Overall image quality of MR digital subtraction and TOF angiograms was compared. The relative ability of MR digital subtraction angiography and TOF MR angiography to demonstrate patent arterial segments was assessed.

RESULTS

MR digital subtraction angiography was significantly superior to TOF MR angiography for demonstration of patent arterial segments and digital arteries (P < .001). MR digital subtraction angiographic images were qualitatively superior to TOF images (P < .001).

CONCLUSION

Two-dimensional MR digital subtraction angiography is superior to two-dimensional TOF MR angiography for help in identifying patent segments in the distal lower extremity.

Bolus-chase MR digital subtraction angiography in the lower extremity

A bolus-chase magnetic resonance (MR) angiographic technique performed with a prototypic stepping table and coil holder and a 15-20-mL injection of contrast material was developed to depict the entire lower extremity. Image acquisition was synchronized with passage of the contrast medium bolus through the lower extremity. Ten subjects underwent the examination, which was performed in less than 1 minute. All major arteries were well demonstrated in all cases.

Genomic instability in the type II TGF-beta1 receptor gene in atherosclerotic and restenotic vascular cells

Cells proliferating from human atherosclerotic lesions are resistant to the antiproliferative effect of TGF-beta1, a key factor in wound repair. DNA from human atherosclerotic and restenotic lesions was used to test the hypothesis that microsatellite instability leads to specific loss of the Type II receptor for TGF-beta1 (TbetaR-II), causing acquired resistance to TGF-beta1. High fidelity PCR and restriction analysis was adapted to analyze deletions in an A10 microsatellite within TbetaR-II. DNA from lesions, and cells grown from lesions, showed acquired 1 and 2 bp deletions in TbetaR-II, while microsatellites in the hMSH3 and hMSH6 genes, and hypermutable regions of p53 were unaffected. Sequencing confirmed that these deletions occurred principally in the replication error-prone A10 microsatellite region, though nonmicrosatellite mutations were observed. The mutations could be identified within specific patches of the lesion, while the surrounding tissue, or unaffected arteries, exhibited the wild-type genotype. This microsatellite deletion causes frameshift loss of receptor function, and thus, resistance to the antiproliferative and apoptotic effects of TGF-beta1. We propose that microsatellite instability in TbetaR-II disables growth inhibitory pathways, allowing monoclonal selection of a disease-prone cell type within some vascular lesions.

Decreased type II/type I TGF-beta receptor ratio in cells derived from human atherosclerotic lesions. Conversion from an antiproliferative to profibrotic response to TGF-beta1

Atherosclerosis and postangioplasty restenosis may result from abnormal wound healing. The present studies report that normal human smooth muscle cells are growth inhibited by TGF-beta1, a potent wound healing agent, and show little induction of collagen synthesis to TGF-beta1, yet cells grown from human vascular lesions are growth stimulated by TGF-beta1 and markedly increase collagen synthesis. Both cell types increase plasminogen activator inhibitor-1 production, switch actin phenotypes in response to TGF-beta1, and produce similar levels of TGF-beta activity. Membrane cross-linking of 125I-TGF-beta1 indicates that normal human smooth muscle cells express type I, II, and III receptors. The type II receptor is strikingly decreased in lesion cells, with little change in the type I or III receptors. RT-PCR confirmed that the type II TGF-beta1 receptor mRNA is reduced in lesion cells. Transfection of the type II receptor into lesion cells restores the growth inhibitory response to TGF-beta1, implying that signaling remains responsive. Because TGF-beta1 is overexpressed in fibroproliferative vascular lesions, receptor-variant cells would be allowed to grow in a slow, but uncontrolled fashion, while overproducing extracellular matrix components. This TGF-beta1 receptor dysfunction may be relevant for atherosclerosis, restenosis and related fibroproliferative diseases.

Hypothermia during elective abdominal aortic aneurysm repair: the high price of avoidable morbidity

PURPOSE

Adverse outcomes apparently associated with hypothermia led us to examine patients undergoing elective abdominal aortic aneurysm (AAA) repairs to test the hypothesis that hypothermia (temperature less than 34.5 degrees C) is associated with increased morbidity and excess mortality rates.

METHODS

Two hundred sixty-two elective AAA repairs were retrospectively reviewed for preoperative and intraoperative risk factors. Core temperature, age, Acute Physiology and Chronic Health Evaluation (APACHE) II and APACHE III scores (raw and temperature-adjusted), fluid resuscitation, and perioperative organ dysfunction were recorded prospectively. Outcome measures included lengths of stay in the intensive care unit and in the hospital, and hospital mortality rates.

RESULTS

Except for a higher risk of hypothermia in women (p < 0.05), by univariate analysis, preoperative risk factors were similar in patients in the hypothermic and normothermic groups. After operation, patients with hypothermia had significantly greater APACHE scores (p < 0.0001), and patients in the hypothermic nonsurvivor group took significantly longer to rewarm (p < 0.05), suggesting marked hypoperfusion. Patients with hypothermia had significantly greater fluid (p < 0.05), transfusion (p < 0.01), vasopressor (p < 0.05), and inotrope (p < 0.05) requirements, resulting in significantly higher incidences of organ dysfunction (53.0% vs 28.7%, p < 0.01) and death (12.1% vs 1.5%, p < 0.01) and markedly prolonged lengths of stay in the unit (9.2 +/- 2.0 vs 5.3 +/- 0.6, p < 0.05) and in the hospital (24.3 +/- 2.9 vs 15.0 +/- 0.08, p < 0.01). By multivariate analysis, female gender (p = 0.004) was the only predictor of intraoperative hypothermia, whereas initial hypothermia was significantly predictive of both prolonged hypothermia and development of organ failure (p < 0.05). Organ failure (p < 0.05) and acute myocardial infarction (p < 0.01) were independent predictors of death.

CONCLUSIONS

After AAA repair, patients with hypothermia have multiple physiologic derangements associated with adverse outcomes. Although multiple etiologic factors are interacting, body temperature is one variable that should be controlled during aortic surgery.

Recurrent systemic embolization caused by aortic thrombi

The aorta is a commonly unrecognized source of systemic embolization. Transesophageal echocardiography is a reliable method for visualization of the intima of the thoracic aorta and identification of aortic thrombi. Balloon embolectomy of the aorta can be used to remove thrombi and prevent further embolic events.

Changes in tibial venous blood flow in the evolving compartment syndrome

A sustained increase in muscle compartment pressures can cause tissue necrosis. When compartment pressures exceed recumbent tibial vein pressures, blood flow in tibial veins may be impaired. These changes can be detected by Doppler venous flow evaluation. In 26 patients at risk for compartment syndrome, serial examinations, Doppler venous flow, and measurements of compartment pressures were performed. All patients with abnormal Doppler venous flow results had or developed neuromuscular deficits. Patients with normal Doppler venous flow either initially or after fasciotomy did not develop the compartment syndrome. This syndrome can be evaluated and followed up sequentially by measuring Doppler venous flow in tibial veins.

Early healing after carotid endarterectomy: effect of high- and low-dose aspirin on thrombosis and early neointimal hyperplasia in a nonhuman primate model

Platelet aggregation and release phenomena are central to most postulated mechanisms of thrombosis and neointimal hyperplasia after carotid endarterectomy. Therefore high-dose aspirin (HDA) has been advocated to minimize these sources of endarterectomy failure. We have defined low-dose aspirin (LDA) that selectively blocks platelet cyclooxygenase but preserves arterial wall cyclooxygenase in the nonhuman primate, Macaca fascicularis. We compared this theoretically optimal aspirin dose with HDA and no treatment (control) in a model of carotid endarterectomy. The aspirin was started before operation and continued for 6 weeks after operation, at which time the endarterectomized vessels were excised. The patency and morphologic findings of the arteries were measured. Platelet function was monitored by bleeding time and serum thromboxane A2 determinations. LDA and HDA were associated with 100% patency, whereas the control group had 50% patency. However, HDA did not protect the vessel from developing neointimal hyperplasia, which was seen in the control group and was associated with platelet adherence to the flow surface at 6 weeks. At 6 weeks, LDA significantly decreased but did not totally prevent neointimal hyperplasia and the flow surface was healed. Therefore the genesis of neointimal hyperplasia after endarterectomy may be more complex than simply a function of platelet-vessel wall interaction.

Effect of chronic low dose aspirin on platelet and vascular eicosanoid metabolism in nonhuman primates (Macaca fascicularis)

It has been suggested that inhibition of platelet cyclooxygenase by chronic low dose aspirin may spare vascular prostacyclin production. Conventional doses of aspirin (greater than 5 mg/kg) have been shown to inhibit the generation of both thromboxane A2 and prostacyclin. Low dose aspirin inhibits prostacyclin production by excised human venous tissue, thus questioning the selectivity of such regimens. However, many clinical and surgical conditions requiring platelet inhibition involve the arterial system. We have studied the effects of various aspirin regimens on platelet, venous, and arterial cyclooxygenase activity in a nonhuman primate (Macaca fascicularis). We determined the lowest chronic dose of oral aspirin required to effectively inhibit platelet cyclooxygenase and aggregation to be 1 mg/kg. After 14 days of 0, 1, or 2 mg/kg aspirin, intact veins and arteries were surgically removed and perfused, and luminal prostacyclin (6-keto-PGF1 alpha) generation was assessed. Levels of 6-keto-PGF1 alpha in venous perfusates were reduced by 89% and 86% (p less than 0.05) after 1 and 2 mg/kg, respectively. Arterial 6-keto-PGF1 alpha levels were unchanged by 1 mg/kg aspirin, but after 2 mg/kg were reduced by 66% (p less than 0.05). Preferential inhibition of platelet over arterial cyclooxygenase is thus achievable, but only over a narrow dose range.

Use of cytomegalovirus immune globulin to prevent cytomegalovirus disease in renal-transplant recipients

We undertook a prospective randomized trial to examine whether an intravenous cytomegalovirus (CMV) immune globulin would prevent primary CMV disease in renal-transplant recipients. Fifty-nine CMV-seronegative patients who received kidneys from donors who had antibodies against CMV were assigned to receive either intravenous CMV immune globulin or no treatment. The immune globulin was administered in multiple doses over the first four months after transplantation. The incidence of virologically confirmed CMV-associated syndromes was reduced from 60 percent in controls to 21 percent in recipients of CMV immune globulin (P less than 0.01). Fungal or parasitic superinfections were not seen in globulin recipients but occurred in 20 percent of controls (P = 0.05). Only 4 percent of globulin recipients had marked leukopenia (reflecting serious CMV disease), as compared with 37 percent of the controls (P less than 0.01). There was a concomitant but not statistically significant reduction in the incidence of CMV pneumonia (17 percent of controls as compared with 4 percent of globulin recipients). A significant reduction in serious CMV-associated disease was observed even when patients were stratified according to therapy for transplant rejection (P = 0.04). We observed no effect of immune globulin on rates of viral isolation or seroconversion, suggesting that treated patients often harbored the virus but that clinically evident disease was much less likely to develop in them. We conclude that CMV immune globulin provides effective prophylaxis in renal-transplant recipients at risk for primary CMV disease.

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.