Malpractice Allegations Against Vascular Surgeons:Prevalence, Risk Factors, and Impact on Surgeon Wellness

OBJECTIVES

The contemporary medicolegal environment has been linked to procedure overuse, healthcare variation, and higher costs. For physicians accused of malpractice, there is also a personal toll. The objective of this study was to evaluate the prevalence of and risk factors for involvement in medical malpractice lawsuits among US vascular surgeons, and to examine the association between these allegations with surgeon wellness.

METHODS

In 2018, the Society of Vascular Surgery (SVS) Wellness Task Force conducted a confidential survey of active members using a validated burnout assessment (Maslach Burnout Index) embedded into a questionnaire. This survey included questions related to medical errors and malpractice litigation. De-identified demographic, personal, and practice-related characteristics were assessed in respondents who reported malpractice allegations in the preceding two years, then compared to those without recent medicolegal litigation. Risk factors for malpractice allegations were identified (chi-square, Kruskal-Wallis tests), and the association between malpractice allegations with wellness was examined. Multivariate logistic regression models were developed to identify independent risk factors for malpractice accusations.

RESULTS

Of 2905 active SVS members, 871 responses from practicing vascular surgeons were analyzed. 161 (18.5%) were named in a malpractice lawsuit within two years. Malpractice allegations were significantly associated with surgeon burnout [OR 1.47 (1.01, 2.15), p=0.041], but not with self-reported depression or suicidal ideation. The nature of malpractice claims included procedural errors (23.1%), failure to treat (18.8%) and error/delay in diagnosis (16.9%). 20% of claims were settled prior to trial and 19% were dismissed. Defendant vascular surgeons reported a "fair" resolution in 26.4% of closed cases. By unadjusted analysis, factors significantly associated with recent malpractice claims included mean age (51.7+/-10.0 vs. 49.3+/-11.2; p=0.0044) and mean years in practice (18.0+/-10.7 vs. 15.2+/-11.8; p=0.0007). Multivariate analysis revealed independent variables associated with malpractice allegations, including on-call frequency (p=0.0178), recent medical errors (p=0.0189), and male surgeons (p=0.045).

CONCLUSIONS

Malpractice allegations are common for vascular surgeons and are significantly associated with surgeon burnout. Nearly 20% of survey respondents reported being named in a lawsuit within the preceding two years. Our findings underscore the need for SVS initiatives to provide counseling and peer support for vascular surgeons facing litigation.

Contribution of the Southern Association for Vascular Surgery to the scientific literature

The Southern Association for Vascular Surgery (SAVS) has played a significant role in the development and evolution of vascular surgery. This study was designed to document the contribution to the scientific literature and to highlight the important publications from the annual meetings of the SAVS on its 25th anniversary. A total of 413 (73%) of the 569 "free papers" presented at the SAVS Annual Meeting were published in journals that are identified in MEDLINE, and most (71%) were published in the Journal of Vascular Surgery. Carotid/cerebrovascular disease, leg ischemia, and basic considerations were the most common subject matters overall, although there has been a recent decrease in the percentage of articles about basic considerations and aortic aneurysms while there has been an increase in those about endovascular therapy, vascular laboratory/imaging, and visceral/renal artery disease. The 413 papers were cited a mean of 18 +/- 20 (+/- SD) times (range 0-143) with 32 papers cited more than 39 times and 17 papers cited more than 59 times. A panel of three reviewers identified 42 significant articles, among which 8 were considered seminal by 2 of the 3 reviewers. The papers presented at the annual meeting of the SAVS have made a significant contribution to the scientific literature in terms of both quantity and quality. These efforts have laid the foundation for the next quarter century and have raised the level of expectation.

The outcome in the United States after thoracoabdominal aortic aneurysm repair, renal artery bypass, and mesenteric revascularization

OBJECTIVES

The purpose of this study was to determine outcome and identify predictors of death after thoracoabdominal aortic aneurysm (TAA) repair, renal artery bypass (RAB), and revascularization for chronic mesenteric ischemia (CMI).

PATIENTS AND METHODS

In this retrospective analysis, data were obtained from the Nationwide Inpatient Sample, a 20% all-payer stratified sample of hospitals in the United States during 1993 to 1997. Patients were identified by the presence of a diagnostic or procedure code from the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM). The main outcomes we examined were death, ICD-9-CM -based complications, length of stay, hospital charges, and disposition. A multivariate model was constructed to predict death.

RESULTS

A total of 2934 patients were identified (TAA, 540; RAB, 2058; CMI, 336) in the database. The mean age was comparable (TAA, 69 +/- 9 years; RAB, 66 +/- 12 years; CMI, 66 +/- 11 years), but the breakdown between the sexes varied by procedure (male: TAA, 53%; RAB, 55%; CMI, 24%). The mortality rate (TAA, 20.3%; RAB, 7.1%; CMI, 14.7%), complication rate (TAA, 62.2%; RAB, 37.4%; CMI, 44.6%), and the percentage of patients discharged to another institution (TAA, 21.2%; RAB, 9.3%; CMI, 12.0%) were clinically significant for all procedures. The mortality rate for RAB was greater when performed concomitant with an aortic reconstruction (4.4% vs 8.3%). All three procedures were resource intensive as reflected by the median length of stay (TAA, 14 days; RAB, 9 days; CMI, 14 days) and median hospital charges (TAA, $64,493; RAB, $36,830; CMI, $47,390). The multivariate model identified several variables for each procedure that had an impact on the predicted mortality rate (TAA, 14%-76%; RAB, < 1%-46%; CMI, < 2%-87%).

CONCLUSIONS

The operative mortality rates across the United States for patients undergoing TAA repair and RAB are greater than commonly reported in the literature and mandate reexamining the treatment strategies for these complex vascular problems.

External-beam radiation therapy for improved dialysis access patency: feasibility and early safety

Rectenwald, J. E., Pretus, H. A., Seeger, J. M., Huber, T. S., Mendenhall, N. P., Zlotecki, R. A., Palta, J. R., Li, Z. F., Hook, S. Y., Sarac, T. P., Welborn, M. B., Klingman, N. V., Abouhamze, Z. S. and Ozaki, C. K. External-Beam Radiation Therapy for Improved Dialysis Access Patency: Feasibility and Early Safety. Radiat. Res. 156, 53-60 (2001).Prosthetic dialysis access grafts fail secondary to neointimal hyperplasia at the venous anastomosis. We hypothesized that postoperative single-fraction external-beam radiation therapy to the venous anastomosis of hemodialysis grafts can be used safely in an effort to improve access patency. Dogs (n = 8) underwent placement of expanded polytetrafluoroethylene grafts from the right carotid artery to the left jugular vein. Five dogs received single-fraction external-beam photon irradiation (8 Gy) to the venous anastomosis after surgery. Controls were not irradiated. Shunt angiograms were completed 3 and 6 months postoperatively. Anastomoses, mid-graft, and the surrounding tissues were analyzed. Immunohistochemistry for smooth muscle cell alpha-actin, proliferating cellular nuclear antigen (PCNA), and apoptosis was performed. Incisions healed well, though all animals developed wound seromas. One control suffered graft thrombosis 4 months postoperatively. Angiography/histology confirmed severe neointimal hyperplasia at the venous anastomosis. The remaining seven dogs developed similar amounts of neointimal hyperplasia. PCNA studies showed no accelerated fibroproliferative response at irradiated anastomoses compared to controls. Skin incisions and soft tissues over irradiated anastomoses revealed no radiation-induced changes or increase in apoptosis. Thus we conclude that postoperative single-fraction external-beam irradiation of the venous anastomosis of a prosthetic arteriovenous graft that mimics the situation in humans is feasible and safe with regard to early wound healing.

Limb salvage surgery with vascular reconstruction

Vascular reconstruction and limb salvage surgery has been the authors' preferred approach when malignancy involves major vessels of the extremities. Treatment of 16 patients involved resection, with vascular grafting in 14 patients and rotationplasty in two patients. The major vessels were surrounded by tumor in six patients, nearly encased in three patients, invaded by tumor in four patients, and widely contaminated by intralesional surgery in three patients. The tumor stage included one Stage IB, 12 Stage IIB, two Stage IIIB sarcomas, and one multiply recurrent carcinoma. The largest average tumor dimension was 9.5 cm, and the length of grafting was 14 cm. Major nerves were sacrificed in eight (50%) patients, flaps or muscle transfers were done in seven (44%), chemotherapy was administered in nine (56%), radiation therapy was used in four (25%), and pulmonary metastasectomy was done in two (12%). At a mean followup of 56 months, 50% (eight of 16) of patients were alive without disease. Local recurrence was 12% (two of 16 patients), and infection was 12% (two of 16 patients). Limb salvage was achieved in 88% (14 of 16 patients), and functional status was judged good or excellent in 81% (13 of 16 patients). The complication rate observed in this subset of patients is significant, yet local control and the incidence of major complications was acceptable. Results observed from this series and data gathered from the literature clearly indicate that patients can avoid amputation, despite malignant involvement of major vessels to their extremities.

Experience in the United States with intact abdominal aortic aneurysm repair

OBJECTIVES

The purpose of this study was to determine the current outcome in the United States and to identify predictors of mortality and "bad outcome" after open, intact abdominal aortic aneurysm (AAA) repair.

METHODS

In a retrospective analysis, data were obtained from the Nationwide Inpatient Sample during 1994-1996. The Nationwide Inpatient Sample is a 20% all-payer stratified sample of nonfederal United States hospitals. Patients older than 49 years were identified by the presence of primary diagnostic (441.4-intact AAA) and procedure (38.44-resection of abdominal aorta with replacement) codes of the International Classification of Diseases, Ninth Revision (ICD-9 ). In-hospital mortality rate, discharge disposition, bad outcome (death or discharge to an institution), complications (ICD-9 postoperative codes), length of stay, and charges were determined. The mortality rate and bad outcome were analyzed by the use of patient demographics (age, sex, race), patient comorbidities (ICD-9 diagnostic codes), calendar year, and hospital characteristics (size, location, teaching status) with univariate and multivariate analyses.

RESULTS

We identified 16,450 intact AAAs repairs during the study years. The mean patient age was 72 +/- 7 (+/- SD) years, and most patients were male (79.7%) and white (94.6%). Most repairs were performed at large (67.3%), urban (92.5%), and nonteaching (66.7%) institutions. The in-hospital mortality rate was 4.2%, the overall complication rate was 32.4%, and 91.2% of patients were discharged home, whereas the bad outcome rate was 12.6%. The median length of stay was 8 days (mean, 10.0 +/- 8.1), and median hospital charges were $28,052 (mean, $35,681 +/- $33,006) in 1996 dollars. Multivariate analysis showed that the mortality rate (P <.05) increased with age (70-79 years, 1.8 odds ratio [OR] [95% CI, 1.4-2.3], > 79 years, 3.8 OR [95% CI, 2.9-4.9]), sex (female, 1.6 OR [95% CI, 1.3-1.9]), cerebral vascular occlusive disease (1.8 OR [95% CI, 1.3-2.5]), preoperative renal insufficiency (9.5 OR [95% CI, 7.7-11.7]), and more than three comorbidities (11.2 OR [95% CI, 3.6-35.4]). Multivariate analysis also showed that bad outcome was associated with the same variables in addition to hospital size (small/medium), year of procedure (1996), chronic obstructive pulmonary disease, and two to three comorbidities.

CONCLUSIONS

Outcome after open repair of intact AAA across the United States is quite good. Older, sicker patients may benefit from nonoperative treatment or the potentially lower risk endovascular approaches.

Direct evidence for cytokine involvement in neointimal hyperplasia

BACKGROUND

Tumor necrosis factor-alpha (TNF-alpha) and interleukin 1 (IL-1) are proximal inflammatory cytokines that stimulate expression of adhesion molecules and induce synthesis of other proinflammatory cytokines. In addition, TNF-alpha and IL-1 influence vascular smooth muscle cell migration and proliferation in vitro. In view of the inflammatory nature of neointimal hyperplasia (NIH), we tested the hypothesis that endogenous TNF-alpha and IL-1 modulate low shear stress-induced NIH.

METHODS AND RESULTS

Mice underwent unilateral common carotid artery (CCA) ligation. Low shear stress in the patent ligated CCA has previously been shown to result in remodeling and NIH. Reverse transcriptase-polymerase chain reaction for TNF-alpha and IL-1alpha mRNA demonstrated both TNF-alpha and IL-1alpha mRNA in ligated CCAs, whereas normal and sham-operated CCAs had none. Mice lacking functional TNF-alpha (TNF-/-) developed 14-fold less neointimal area than WT controls (P:<0.05). p80 IL-1 type I receptor knockout (IL-1RI-/-) mice tended to develop less (7-fold, P:>0.05) neointimal area than WT controls. Furthermore, no IL-1alpha mRNA expression was detected in CCAs from TNF-/- mice; however, TNF-alpha mRNA expression was found in the IL-1RI-/- mice. Mice that overexpress membrane-bound TNF-alpha but produce no soluble TNF-alpha display an accentuated fibroproliferative response to low shear stress (P:<0.05).

CONCLUSIONS

These results directly demonstrate that TNF-alpha and IL-1 modulate NIH induced by low shear stress. NIH can proceed by way of soluble TNF-alpha-independent mechanisms. Specific anti-TNF-alpha and anti-IL-1 therapies may lessen NIH.

The relationship between visceral ischemia, proinflammatory cytokines, and organ injury in patients undergoing thoracoabdominal aortic aneurysm repair

OBJECTIVES

Plasma proinflammatory, anti-inflammatory cytokine, and soluble tumor necrosis factor (TNF) receptor concentrations were examined in hospitalized patients after abdominal and thoracoabdominal aortic aneurysm (TAAA) repair, with and without left atrial femoral bypass. Changes in plasma cytokine concentrations were related to the duration of visceral ischemia and the frequency rate of postoperative, single, or multiple system organ dysfunction (MSOD).

DESIGN

Prospective, observational study.

SETTING

Two academic referral centers in the United States and The Netherlands.

PATIENTS

We included 16 patients undergoing TAAA repair without left atrial femoral bypass, 12 patients undergoing TAAA repair with left atrial femoral bypass, and nine patients undergoing infrarenal aortic aneurysm repair.

MEASUREMENTS AND MAIN RESULTS

Timed, arterial blood sampling for proinflammatory and anti-inflammatory cytokine and soluble TNF receptor concentrations (p55 and p75), and prospective assessment of postoperative single and MSOD. Plasma appearance of TNF-alpha, interleukin (IL)-6, IL-8, and IL-10 peaked 1 to 4 hrs after TAAA repair, and concentrations were significantly elevated compared with infrarenal abdominal aortic aneurysm repair (p < .05). Left atrial femoral bypass significantly reduced the duration of visceral ischemia (p < .05) and the systemic TNF-alpha, p75, and IL-10 responses (p < .05). Plasma TNF-alpha concentrations >150 pg/mL were more common in patients with extended visceral ischemia times (>40 mins). Additionally, patients with early peak TNF-alpha concentrations >150 pg/mL and IL-6 levels >1,000 pg/mL developed MSOD more frequently than patients without these elevated plasma cytokine levels (both p < .05).

CONCLUSIONS

Thoracoabdominal aortic aneurysm repair results in the increased plasma appearance of TNF-alpha, IL-6, IL-8, IL-10, and shed TNF receptors. The frequency and magnitude of postoperative organ dysfunction after TAAA repair is associated with an increased concentration of the cytokines, TNF-alpha, and IL-6 and the increased plasma levels of these cytokines appear to require extended visceral ischemia times.

Long-term outcome after treatment of aortic graft infection with staged extra-anatomic bypass grafting and aortic graft removal

OBJECTIVE

The purpose of this study was to determine long-term outcome in patients with infected prosthetic aortic grafts who were treated with extra-anatomic bypass grafting and aortic graft removal.

METHODS

Between January 1989 and July 1999, 36 patients were treated for aortic graft infection with extra-anatomic bypass grafting and aortic graft removal. Extra-anatomic bypass graft types were axillofemoral femoral (5), axillofemoral (26; bilateral in 20), axillopopliteal (3; bilateral in 1) and axillofemoral/axillopopliteal (2). The mean follow-up was 32.3 +/- 4. 8 months.

RESULTS

Four patients (11%) died in the postoperative period, and two patients died during follow-up as a direct consequence of extra-anatomic bypass grafting and aortic graft removal (one died 7 months after extra-anatomic bypass graft failure, one died 36 months after aortic stump disruption). One additional patient died 72 months after failure of a subsequent aortic reconstruction, so that the overall treatment-related mortality was 19%, whereas overall survival by means of life table analysis was 56% at 5 years. No amputations were required in the postoperative period, but four patients (11%) required amputation during follow-up. Twelve patients (35%) had extra-anatomic bypass graft failure during follow-up, and six patients underwent secondary aortic reconstruction (thoracobifemoral [2], iliofemoral [2], femorofemoral [2]). However, with the exclusion of patients undergoing axillopopliteal grafts (primary patency 0% at 7 months), only seven patients (25%) had extra-anatomic bypass graft failure, and only two patients required amputation (one after extra-anatomic bypass graft removal for infection, one after failure of a secondary aortic reconstruction). Furthermore, primary and secondary patency rates by means of life table analysis were 75% and 100% at 41 months for axillofemoral femoral grafts and 64% and 100% at 60 months for axillofemoral grafts. Only one patient required extra-anatomic bypass graft removal for recurrent infection, and only one late aortic stump disruption occurred.

CONCLUSIONS

Staged extra-anatomic bypass grafting (with axillofemoral bypass graft) and aortic graft removal for treatment of aortic graft infection are associated with acceptable early and long-term outcomes and should remain a primary approach in selected patients with this grave problem.

Laparotomy prevents lethal endotoxemia in a murine sequential insult model by an IL-10-dependent mechanism

Multiple organ dysfunction and death are common sequelae after mesenteric ischemia-reperfusion injury as seen with mesenteric revascularization and thoracoabdominal aortic aneurysm repair. A second insult such as bacterial pneumonia occurring subsequent to the ischemia-reperfusion injury may contribute to these untoward effects. We hypothesized the sequential visceral/lower torso ischemia-reperfusion and endotoxemia in a murine model would increase the magnitude of the proinflammatory cytokine response and decrease survival. C57BL/6 mice underwent 20 min of supraceliac occlusion (IR), sham laparotomy (LAP), or no initial insult (CTRL) followed by intraperitoneal injection of a lethal dose of endotoxin (LPS [lipopolysaccharide 50 mg/kg] or saline vehicle at 24 h. Serum cytokine levels were measured by enzyme-linked immunosorbent assay (IL-10, IL-6) or WEHI bioassay [tumor necrosis factor (TNF)], and survival was determined at 5 days. The role of IL-10 on the TNF response and survival was examined in a subset of mice given mouse anti IL-10 IgM (25 mg/kg intraperitoneally) 2 h prior to the initial insult. Survival after LPS was significantly different (P < 0.05) among the treatment groups (IR, 64%; LAP, 55%; CTRL, 11%) and appeared to trend directly with the magnitude of the initial operation. The serum IL-10 levels in the IR and LAP groups were significantly increased 4 h after the initial insult and remained elevated at 24 h. Peak serum TNF levels after LPS were significantly lower in the IR and LAP groups. Administration of anti IL-10 IgM resulted in uniform mortality and a significant increase in the peak TNF levels after LPS administration for all initial treatment groups. Endogenous production of IL-10 following laparotomy down-regulates the TNF response and improves survival after endotoxemia.

Anticytokine therapies for acute inflammation and the systemic inflammatory response syndrome: IL-10 and ischemia/reperfusion injury as a new paradigm

The results of recent anticytokine trials for sepsis syndrome have been disappointing. Several Phase II and Phase III clinical trials have shown a modest benefit in various subsets of patients; however, there has been no reported benefit in the primary endpoint of 28-day all-cause mortality. The failure of these trials is clearly multifactorial, and causes include the overall complexity of the inflammatory response, heterogeneity of the patient populations, absence of a hypercytokine response at the time of drug treatment, and the relatively short half-life of the administered drugs. The failure of anticytokine therapies may represent inadequate application of the treatment modality rather than any inherent weakness of the treatment itself. We have recently initiated a Phase I clinical trial examining the role of the anti-inflammatory cytokine IL-10 during surgical repair of a thoracoabdominal aortic aneurysm. This study may overcome some of the-design limitations of previous anticytokine trials in sepsis, and serve as a paradigm for future anticytokine therapy trials. Although the incidence of thoracoabdominal aortic aneurysms is relatively low, the patient population is homogeneous and the surgical injury associated with its repair reproducible. Additionally, postoperative mortality and morbidity rates are significant. Most importantly, the operative repair is associated with an obligatory visceral ischemia and reperfusion injury that appears to be associated with a proinflammatory cytokine response and postoperative organ dysfunction. IL-10 is a pleuripotent anti-inflammatory cytokine that both inhibits TNFalpha and IL-1 synthesis, and antagonizes their actions through upregulation of cytokine antagonists. Furthermore, IL-10 administration has been associated with only minimal adverse side effects during Phase I and Phase II trials.

Financial impact of tertiary care in an academic medical center

OBJECTIVE

To analyze the financial impact of three complex vascular surgical procedures to both an academic hospital and a department of surgery and to examine the potential impact of decreased reimbursements.

SUMMARY BACKGROUND DATA

The cost of providing tertiary care has been implicated as one potential cause of the financial difficulties affecting academic medical centers.

METHODS

Patients undergoing revascularization for chronic mesenteric ischemia, elective thoracoabdominal aortic aneurysm repair, and treatment of infected aortic grafts at the University of Florida were compared with those undergoing elective infrarenal aortic reconstruction and carotid endarterectomy. Hospital costs and profit summaries were obtained from the Clinical Resource Management Office. Departmental costs and profit summary were estimated based on the procedural relative value units (RVUs), the average clinical cost per RVU ($33.12), surgeon charges, and the collection rate for the vascular surgery division (30.2%) obtained from the Faculty Group Practice. Surgeon work effort was analyzed using the procedural work RVUs and the estimated total care time. The analyses were performed for all payors and the subset of Medicare patients, and the potential impact of a 15% reduction in hospital and physician reimbursement was analyzed.

RESULTS

Net hospital income was positive for all but one of the tertiary care procedures, but net losses were sustained by the hospital for the mesenteric ischemia and infected aortic graft groups among the Medicare patients. In contrast, the estimated reimbursement to the department of surgery for all payors was insufficient to offset the clinical cost of providing the RVUs for all procedures, and the estimated losses were greater for the Medicare patients alone. The surgeon work effort was dramatically higher for the tertiary care procedures, whereas the reimbursement per work effort was lower. A 15% reduction in reimbursement would result in an estimated net loss to the hospital for each of the tertiary care procedures and would exacerbate the estimated losses to the department.

CONCLUSIONS

Caring for complex surgical problems is currently profitable to an academic hospital but is associated with marginal losses for a department of surgery. Economic forces resulting from further decreases in hospital and physician reimbursement may limit access to academic medical centers and surgeons for patients with complex surgical problems and may compromise the overall academic mission.

Use of superficial femoral vein for hemodialysis arteriovenous access

Maintaining hemodialysis access in the expanding number of patients with end-stage renal disease is a difficult and challenging problem. Published guidelines outline the initial recommendations for hemodialysis access; however, there is little consensus about the most appropriate options for the subset of patients with repeated access failures and/or unsuitable veins. Two case reports are presented describing the use of composite saphenous-superficial femoral vein autogenous accesses placed in the upper and lower extremities. The function of the autogenous accesses appeared to be similar to a mature arteriovenous fistula in the short-term, although further longitudinal studies are required. The superficial femoral vein may be a useful hemodialysis access conduit for patients with limited access options.

Potential predictors of outcome in patients with tissue loss who undergo infrainguinal vein bypass grafting

PURPOSE

Aggressive attempts at limb salvage in patients with ischemic tissue loss are justified by favorable initial results in most patients. The identification of patients whose conditions will not benefit from attempted revascularization remains difficult.

METHODS

This study was designed as a retrospective review of prospectively collected clinical data. The subjects were 210 consecutive patients who underwent infrainguinal vein bypass grafting for ischemic tissue loss in the setting of an academic medical center. Bypass grafting was to the popliteal artery in 56 patients, to the infrapopliteal arteries in 131 patients, and to the pedal arteries in 23 patients. The follow-up examination was complete in 209 of 210 patients. One hundred twenty-five patients underwent blinded review of duplex scan venous mapping and arteriography to determine simplified vein and run-off scores. The outcome measures were the influence of risk factors, venous conduit, and runoff on mortality, limb loss, and graft failure at the 6-month follow-up examination.

RESULTS

One hundred seventy patients (81%) were alive and had limb salvage. Nineteen patients (9.1%) died, with need for a simultaneous inflow procedure and end-stage renal disease being most commonly associated with mortality. Thirty-three patients (15.8%) had undergone amputation: 18 after graft failure, and 15 for progressive tissue loss despite a patent graft. Amputation was significantly more common in patients with diabetes (P =.05) and with poor runoff scores (poor runoff, 44.4% vs good runoff, 7.4%; P <.01). Amputation despite a patent graft also correlated with runoff (poor runoff, 41.7% vs good runoff, 4.3%; P <.01). Twenty-five patients had graft failure without amputation, so that only 145 patients (69.4%) were alive, had limb salvage, and had a patent graft. Run-off score was the strongest predictor of outcome, with 70% of patients with poor run-off scores having death, amputation, or graft failure.

CONCLUSION

Aggressive use of infrainguinal vein bypass grafting in patients with ischemic tissue loss results in a high rate of initial limb salvage but significant morbidity and mortality. Arteriographically determined runoff scores appear to potentially identify patients at high risk for a poor initial outcome and may provide a method of selecting patients for primary amputation.

Surgical decision making for carotid endarterectomy and contemporary magnetic resonance angiography

BACKGROUND

Benefit from carotid endarterectomy (CEA) centers on patient selection and percent stenosis as determined by cerebral angiography. However, angiography remains expensive and poses risks. Validated carotid duplex ultrasonography has proven to be an accurate tool for selecting patients for CEA. However, the role of another noninvasive test-magnetic resonance angiography (MRA)-remains uncertain. Because of recent advances in MRA hardware and software, we hypothesized that clinically appropriate patients could be accurately selected for CEA based on MRA alone.

METHODS

Fifty-four carotid arteries in 29 patients (with and without symptoms) underwent both three-dimensional time-of-flight MRA (1.5 Tesla) with multiple overlapping thin slab acquisition and biplanar intra-arterial digital subtraction angiography. All patients undergoing both tests over a 24-month period were included. The majority of these patients did not undergo carotid duplex ultrasound owing to the clinical practice of the hospital's neurosurgery service. Staff radiologists interpreted each study. The accuracy of patient selection based on MRA was calculated using angiography as the standard (NASCET method). Since operative thresholds vary depending on clinical history, we considered four commonly used ranges of percent stenosis for CEA.

RESULTS

Patient selection accuracy of MRA alone was low, but increased as percent stenosis increased. Out of 10 occluded arteries by angiography, 5 were interpreted as patent with stenosis (70% to 99%) by MRA. One patent artery was misread as occluded on MRA.

CONCLUSION

Reliance solely on contemporary MRA for surgical decision making cannot be justified in view of low accuracy, which leads to high rates of error in patient selection for CEA.

Impact of race on the treatment for peripheral arterial occlusive disease

PURPOSE

The purpose of this study was to determine the impact of race on the treatment of peripheral artery occlusive disease (PAOD) and to examine the role of access to care and disease distribution on the observed racial disparity.

METHODS

The study was performed as a retrospective analysis of hospital discharge abstracts from 1992 to 1995 in 202 non-federal, acute-care hospitals in the state of Florida. The subjects were patients older than 44 years of age who underwent major lower extremity amputation or revascularization (bypass grafting or angioplasty) for PAOD. The main outcome measures were incidence of intervention, incidence per demographic group, multivariate predictors of amputation versus revascularization, multivariate predictors of amputation versus revascularization among those patients with access to sophisticated care (hospital with arteriographic capabilities), and multivariate predictors of surgical bypass graft type (aortoiliac vs infrainguinal).

RESULTS

A total of 51,819 procedures (9.1 per 10,000 population) were performed for PAOD during the study period and included 15,579 major lower extremity amputations (30.1%) and 36,240 revascularizations (69.9%). Although the incidence of a procedure for PAOD was comparable between African Americans and whites (9.0 vs 9.6 per 10, 000 demographic group), the incidence of amputation (5.0 vs 2.5 per 10,000 demographic group) was higher and the incidence of revascularization (4.0 vs 7.1 per 10,000 demographic group) was lower among African Americans. Furthermore, multivariate analysis results showed that African Americans (odds ratio, 3.79; 95% confidence interval [CI], 3.34 to 4.30) were significantly more likely than whites to undergo amputation as opposed to revascularization. The secondary multivariate analyses results revealed that African Americans (odds ratio, 2.29; 95% CI, 1.58 to 3. 33) were more likely to undergo amputation among those patients (n = 9193) who underwent arteriography during the procedural admission and to undergo infrainguinal bypass grafting (odds ratio, 2.00; 95% CI, 1.48 to 2.71) among those patients (n = 27,796) who underwent surgical bypass grafting.

CONCLUSION

There is a marked racial disparity in the treatment of patients with PAOD that may be caused in part by differences in the severity of disease or disease distribution.

Influence of patient characteristics and treatment options on outcome of patients with prosthetic aortic graft infection

This study was undertaken to determine the influence of patient characteristics and treatment options on survival and limb loss after treatment of prosthetic aortic graft infection. Fifty-three patients treated for prosthetic aortic graft infection were reviewed. Twenty-three presented with groin infection, 12 with sepsis, 10 with aortoenteric fistula, 4 with limb ischemia, and 4 with pseudoaneurysm. Treatment included staged extraanatomic bypass (EAB) plus graft excision in 23 patients, simultaneous EAB and graft excision in 18, in situ graft replacement in 5, and local therapy only in 7. Axillofemoral bypass was done for revascularization in 53 limbs and axillopopliteal bypass in 16 limbs. The results of this study showed that morbidity and mortality of prosthetic aortic graft infection is influenced by the presentation and type of treatment of the infected graft. Staged axillofemoral bypass (when possible) plus graft excision appears to be associated with acceptable outcome (survival with limb salvage in 74%).

Attenuation of skeletal muscle ischemia/reperfusion injury by inhibition of tumor necrosis factor

PURPOSE

Tumor necrosis factor alpha (TNF-alpha) has been shown to play a role in pulmonary injury after lower-extremity ischemia/reperfusion (I/R). However, its role in direct skeletal muscle injury is poorly understood. The hypothesis that endogenous TNF production contributes to skeletal muscle injury after hindlimb I/R in rats was tested.

METHODS

Juvenile male Sprague-Dawley rats underwent 4 hours of bilateral hindlimb ischemia and 4 hours of reperfusion (IR) or sham operation (SHAM). A subset was treated with a soluble TNF receptor I construct (STNFRI, 10 mg/kg) 1 hour before ischemia (PRE) or at reperfusion (POST). Direct skeletal muscle injury (SMII) and muscle endothelial capillary permeability (MPI) were quantified by means of Tc99 pyrophosphate and I125 albumin uptake. Pulmonary neutrophil infiltration and hepatocellular injury were assessed by means of myeloperoxidase content (MPO) and aspartate aminotransferase (AST) concentrations, respectively. Serum TNF bioactivity was measured with the WEHI bioassay.

RESULTS

Hindlimb I/R (IR vs SHAM) resulted in a significant (P <.05) increase in the SMII (0.52 +/- 0.06 vs 0.07 +/- 0.01) and MPI (0.35 +/-.04 vs 0.06 +/- 0.01). Pretreatment with STNFRI (PRE vs IR) significantly ameliorated both SMII (0.30 +/- 0.05 vs 0.52 +/- 0.06) and MPI (0.23 +/- 0.02 vs 0.35 +/- 0.04), whereas treatment at reperfusion (POST vs IR) had no effect. Hindlimb I/R (IR vs SHAM) resulted in both significant pulmonary neutrophil infiltration (MPO 16.4 +/- 1.06 U/g vs 11.3 +/- 1.4 U/g) and hepatocellular injury (AST 286 +/- 45 U/mL vs 108 +/- 30 U/mL), but neither was inhibited by pretreatment with STNFRI before ischemia. Detectable levels of TNF were measured during ischemia in a significantly higher percentage of the IR group compared with SHAM (9 of 12 vs 3 of 12), and the maximal TNF values were also significantly greater (51.1 +/- 12.6 pg/mL vs 5.5 +/- 2.9 pg/mL). No TNF was detected in any treatment group during reperfusion nor after administration of the STNFRI.

CONCLUSION

Acute hindlimb IR initiates a systemic TNF response during the ischemic period that is partly responsible for the associated skeletal muscle injury.

Carotid surgery in octogenarians in Veterans Affairs medical centers

The purpose of this study was to define outcomes after carotid surgery in octogenarians in the Veterans Affairs health care system. During fiscal years 1991-1994, 9152 patients in DRG 5 underwent extracranial vascular surgery procedures in Veterans Affairs medical centers. Those >/=80 years of age constituted 2.1% (n = 195) of such patients. In-hospital mortality rates were 1.03% (92/8957) in those <80 versus 3.08% (6/195) in those >/=80 years old (P = 0.018). Of those >/=80, 11.8% (23/195) had an ICD-9-CM-coded complication during hospitalization versus 11.2% of those <80 (1004/8957, NS). Surgical complications of the central nervous system (CNS) were present in 0.51% of octogenarians (1/195) and in 0.93% of those younger (83/8957, NS). Myocardial infarction (MI) occurred in 1.0% (2/195) of octogenarians and 0.74% (66/8967) of younger patients (NS). Patient Management Category software was used to define illness severity and resource intensity scale (RIS, a measure of resource utilization). Logistic regression analysis showed that age, illness severity, MI, and surgical complications of the CNS were associated with greater likelihood of mortality after extracranial vascular surgery. When the dichotomous variable "octogenarian status" was substituted for the continuous variable "age," in this model, there was no significant association of octogenarian status per se with mortality, though the association of illness severity, MI, and CNS complications with mortality persisted. Illness severity was greater for octogenarians (2.03 +/- 1.36) versus those younger (1.84 +/- 1.13, P < 0.05). RIS was 2.57 +/- 0.57 in octogenarians versus 2.47 +/- 0.48 for younger patients (P < 0.015). Length of stay (LOS) was a mean of 3.2 days longer for octogenarians (P < 0. 001). The risk of postoperative CNS complications was not higher in octogenarians. Mortality, resource utilization, and length of stay were, however, greater for octogenarians, but so was illness severity. Though mortality rates were greater for octogenarians in DRG 5, illness severity, MI, and postoperative CNS complications had greater impact on mortality after extracranial vascular surgery than octogenarian status per se.

Warfarin improves the outcome of infrainguinal vein bypass grafting at high risk for failure

OBJECTIVE

Patients with marginal venous conduit, poor arterial runoff, and prior failed bypass grafts are at high risk for infrainguinal graft occlusion and limb loss. We sought to evaluate the effects of anticoagulation therapy after autogenous vein infrainguinal revascularization on duration of patency, limb salvage rates, and complication rates in this subset of patients.

METHODS

This randomized prospective trial was performed in a university tertiary care hospital and in a Veterans Affairs Hospital. Fifty-six patients who were at high risk for graft failure were randomized to receive aspirin (24 patients, 27 bypass grafts) or aspirin and warfarin (WAR; 32 patients, 37 bypass grafts). All patients received 325 mg of aspirin each day, and the patients who were randomized to warfarin underwent anticoagulation therapy with heparin immediately after surgery and then were started on warfarin therapy to maintain an international normalized ratio between 2 and 3. Perioperative blood transfusions and complications were compared with the Student t test or with the chi2 test. Graft patency rates, limb salvage rates, and survival rates were compared with the Kaplan-Meier method and the log-rank test.

RESULTS

Sixty-one of the 64 bypass grafts were performed for rest pain or tissue loss, and 3 were performed for short-distance claudication. There were no differences between the groups in ages, indications, bypass graft types, risk classifications (ie, conduit, runoff, or graft failure), or comorbid conditions (except diabetes mellitus). The cumulative 5-year survival rate was similar between the groups. The incidence rate of postoperative hematoma (32% vs 3.7%; P = .004) was greater in the WAR group, but no differences were seen between the WAR group and the aspirin group in the number of packed red blood cells transfused, in the incidence rate of overall nonhemorrhagic wound complications, or in the overall complication rate (62% vs 52%). The immediate postoperative primary graft patency rates (97.3% vs 85.2%) and limb salvage rates (100% vs 88.9%) were higher in the WAR group as compared with the aspirin group. Furthermore, the cumulative 3-year primary, primary assisted, and secondary patency rates were significantly greater in the WAR group versus the aspirin group (74% vs 51%, P = .04; 77% vs 56%, P = .05; 81% vs 56%, P = .02) and cumulative limb salvage rates were higher in the WAR group (81% vs 31%, P = .01).

CONCLUSIONS

Perioperative anticoagulation therapy with heparin increases the incidence rate of wound hematomas, but long-term anticoagulation therapy with warfarin improves the patency rate of autogenous vein infrainguinal bypass grafts and the limb salvage rate for patients at high risk for graft failure.

Effect of the Asymptomatic Carotid Atherosclerosis Study on carotid endarterectomy in Florida

BACKGROUND AND PURPOSE

The value of carotid endarterectomy (CEA) has been defined by several recent multicenter trials. The clinical effect of these trials remains undetermined since the Asymptomatic Carotid Atherosclerosis Study (ACAS) Clinical Advisory (dated September 28, 1994).

METHODS

Patients undergoing CEA (ICD-9-CM 38.12) in nonfederal Florida hospitals were identified from the discharge database. Data were analyzed by federal fiscal year (FY, October 1 through September 30), comparing the years following the Advisory (FY95-FY96) to the preceding 3 years (FY92-FY94).

RESULTS

There was a 68.3% increase in the number of CEAs during FY95-FY96 (mean FY92-FY94, 7,343; mean FY95-FY96, 12,356). This exceeded increases in total hospital discharges (4.5%), surgical discharges (2.2%), and the state's population (4.7%). The increase in CEAs spanned all patient demographic groups (gender, race, and age), although the magnitude was not consistent (range, 57.8% increase for 55 to 64 age group; 92.9% increase for > 84 age group). Concomitantly, there was a significant decrease in mortality (1.2% versus 0.8%), cardiac complication rate (ICD-9-CM 997.1, 4.1% versus 3.0%) and percentage of patients discharged > 7 days postoperatively (8.9% versus 4.9%). Mean length of stay declined 28% (5.8 versus 4.1 days), and mean adjusted charges declined 7% ($19,456 versus $18,055). Although the average case was less costly, the increased volume resulted in an estimated $56 million increase in annual hospital payments.

CONCLUSIONS

The dramatic increase in the number of CEAs performed in the state of Florida after release of the ACAS Clinical Advisory suggests a causal relationship and mandates further cost-effectiveness analyses.

Impact of a clinical pathway for elective infrarenal aortic reconstructions

OBJECTIVE

To determine the impact of a clinical pathway for elective infrarenal aortic reconstruction on outcome, resource utilization, and cost in a university medical center.

SUMMARY BACKGROUND DATA

Clinical pathways have been reported to control costs, reduce resource utilization, and maintain or improve the quality of patient care, although their use during elective aortic reconstructions remains unresolved.

METHODS

A clinical pathway was developed for elective infrarenal aortic reconstructions by a multidisciplinary group comprised of representatives from each involved service. The prepathway practice and costs were analyzed and an efficient, cost-effective practice with specific outcome measures was defined. The impact of the pathway was determined by retrospective comparison of outcome, resource utilization, and cost (total and direct variable) between the pathway patients (PATH, n = 45) and a prepathway control group (PRE, n = 20).

RESULTS

There were no significant differences in the patient demographics, comorbid conditions, operative indications, or type of reconstruction between the groups. There were no operative deaths and the overall complication rate (PRE, 35% vs. PATH, 34%) was similar. The pathway resulted in significant decreases in the total length of stay and preoperative length of stay and a trend toward a significant decrease (p = 0.08) in the intensive care length of stay for the admission during which the operation was performed. The pathway also resulted in significant decreases in both direct variable and total hospital costs for this admission, as well as a significant decrease in the overall direct variable and total hospital costs for the operative admission and the preoperative evaluation (< or =30 days before operative admission). Despite these reductions, the discharge disposition, 30-day readmissions, and number of postoperative clinic visits within 90 days of discharge were not different.

CONCLUSIONS

Implementation of a clinical pathway for elective infrarenal aortic reconstructions dramatically decreased resource utilization and hospital costs without affecting the quality of patient care and did not appear to shift the costs to another setting.

Effect of the Asymptomatic Carotid Atherosclerosis Study on carotid endarterectomy in Veterans Affairs medical centers

OBJECTIVE

To examine the effect of the Asymptomatic Carotid Atherosclerosis Study on the volume of carotid endarterectomies (CEAs) performed in Veterans Affairs medical centers.

DESIGN

The data were retrospectively extracted from the Veterans Affairs Patient Treatment File for all patients undergoing CEA using the International Classification of Diseases, Ninth Revision, Clinical Modification procedural code 38.12. Data were classified into patient management categories to identify complications and to quantify the severity of illnesses and comorbidities.

SETTING

All 172 US Veterans Affairs medical centers.

PATIENTS

Veterans undergoing CEA during fiscal years 1993 through 1995.

MAIN OUTCOME MEASURES

Procedural volume, mortality, and morbidity.

RESULTS

There was a 43.4% increase in the volume of CEAs performed in fiscal year 1995 despite a 4.6% decrease in the served inpatients and an 8.8% decrease in the inpatient surgical procedures. The monthly volume of CEAs increased (P < .001, r2 = 0.78) at the onset of the fiscal year (October 1994) immediately after the Asymptomatic Carotid Atherosclerosis Study clinical advisory. The volume of CEAs increased in every region of the country for all nonpsychiatric hospital classifications and for almost every surgeon subspecialty. Despite the increased volume, the operative mortality rate, the International Classification of Diseases, Ninth Revision, Clinical Modification--and patient management categories--based complication rates, and the patients' comorbidity and severity of illness indexes all remained unchanged.

CONCLUSION

The dramatic increase in CEAs following the Asymptomatic Carotid Atherosclerosis Study clinical advisory suggests that the conclusions of the trial have been accepted by the medical community throughout the Veterans Affairs medical centers.

Utility of magnetic resonance arteriography for distal lower extremity revascularization

PURPOSE

Magnetic resonance arteriography (MRA) of the lower extremities affords several possible advantages over conventional contrast arteriography (CA). We hypothesized that MRA of the infrageniculate vessels was sufficiently accurate to replace CA before revascularization procedures in patients with limb-threatening ischemia.

METHODS

Fifty-three extremities in 49 patients were prospectively evaluated before attempted infrageniculate revascularization procedures with preoperative infrageniculate time-of-flight MRA (cost, $170/study) and standard contrast arteriography (cost, $1310/study) of the aortoiliac and runoff vessels. Independent operative plans were formulated based on the MRA and CA results before the revascularization procedure. Intraoperative, prebypass arteriograms (IOA; cost, $46/study) were obtained in all patients to confirm the adequacy of the distal runoff. The preoperative plans formulated by the results of MRA and CA were compared with the actual procedure performed based on the IOA. All arteriograms (CA, MRA, IOA) were reviewed after the operation by two independent reviewers, and the number of patent vessel segments and those with < 50% stenosis was determined.

RESULTS

Revascularization procedures were performed in 44 of 53 extremities (83%), and amputation was performed in nine extremities (17%) because of an absence of a suitable bypass target. The CA and MRA were equally effective in predicting the optimal operative plans as determined from IOA (CA, 42 of 53 [77%] vs MRA, 40 of 53 [75%]; p = 0.79). More patent vessel segments were seen on CA than MRA (reviewer A, 229 vs 174, kappa = 0.32; reviewer B, 321 vs 314, kappa = 0.46); however, a comparable number of segments were seen if the vessels of the foot were excluded. The accuracy (reviewer A, 78% vs 68%, p = 0.003; reviewer B, 75% vs 67%, p = 0.003) and sensitivity (reviewer A, 69% vs 51%, p = 0.001; reviewer B, 68% vs 46%, p = 0.0001) of CA relative to IOA were superior to those of MRA, although the specificity was comparable (reviewer A, 86% vs 90%, p = 0.31; reviewer B, 82% vs 87%, p = 0.52). The combination of MRA and IOA would have resulted in the optimal operative plan in 51 of the 53 cases (96%) and was comparable with CA and IOA (53 of 53; 100%; p = 0.50). Substitution of MRA and IOA for CA and IOA could potentially have saved an estimated $60,420.

CONCLUSIONS

The combination of MRA and IOA provides an accurate, cost-efficient strategy for visualization of the infrageniculate vessels before revascularization procedures.

Improving the cost-effectiveness of carotid endarterectomy

PURPOSE

Carotid endarterectomy (CEA) has been shown to significantly reduce the risk of stroke caused by carotid artery stenosis. Limiting the costs of CEA without increasing the risks will improve the cost-effectiveness of this procedure.

METHODS

Results were prospectively collected from 63 consecutive CEAs performed in 60 patients who were entered into a clinical pathway for CEA that included avoidance of cerebral arteriography, preferential use of regional anesthesia, selective use of the intensive care unit (ICU), and early hospital discharge. The mortality rate, complications, hospital costs, and net income in these patients were then compared with results from 45 CEAs performed in 42 consecutive patients immediately before beginning the CEA pathway. Age, comorbid risk factors, incidence of symptoms, and degree of carotid artery stenosis were similar in both patient groups.

RESULTS

The rates of mortality and complications associated with CEA were low (mortality rate, 0%; stroke, 0.9%; transient ischemic attack, 2.8%) and did not vary between the two groups. Implementation of the CEA pathway resulted in significant (p < 0.001) reductions in the use of arteriography (74% to 13%), general anesthesia (100% to 24%), ICU use (98% to 30%), and mean hospital length of stay (5.8 days to 2.0 days). These changes resulted in a 41% reduction in mean total hospital cost ($9652 to $5699) and a 124% increase in mean net hospital income ($1804 to $4039) per CEA (p < 0.01). For the 39 patients (62%) who achieved all elements of the CEA pathway, the mean hospital length of stay was 1.3 days, the mean hospital cost was $4175, and the mean hospital income was $4327.

CONCLUSIONS

Costs associated with CEA can be reduced substantially without increased risk. This makes CEA an extremely cost-effective treatment of carotid disease against which new therapeutic approaches must be measured.

Intraoperative prebypass arteriography for infrageniculate revascularization

BACKGROUND

Selection of the optimal distal target for infrageniculate arterial revascularization remains difficult in patients with multilevel occlusive disease due to poor visualization of the distal vasculature by preoperative arteriography. Prebypass, intraoperative arteriography (IOA) with direct injection of contrast into the infrageniculate arteries may improve distal arterial visualization and bypass target selection.

METHODS

One hundred fourteen extremities in 104 consecutive patients requiring infrageniculate bypass were prospectively studied. All patients underwent preoperative contrast arteriography (CA) of the aortoiliac and lower extremity arteries using iodinated and/or CO2 contrast and digital subtraction techniques. IOAs were obtained at operation to confirm the adequacy of the distal runoff from the predicted bypass target and to identify potentially superior targets. The preoperative plan formulated from the CA was compared to the actual procedure performed based on the IOA. The CA and IOA were also independently reviewed postoperatively by two blinded vascular surgeons to determine the number of patent vessel segments visualized and the number of segments with <50% stenosis.

RESULTS

Revascularization was done in 105 of 114 extremities (92%), whereas amputation was required as the initial procedure in 9 patients (8%). The IOA altered the operative plan based on the CA in 27 of 144 patients (24%). Changes in the planned bypass procedures included selection of a more distal anastomotic site in 13 of 102 patients (13%), selection of a more proximal anastomotic site in 4 of 102 (4%), selection of a different artery for the distal anastomosis in 3 of 102 (3%), and amputation rather than bypass in 2 of 102 patients (2%) with no suitable distal bypass target on the IOA. The IOA also resulted in bypass rather than planned amputation in 5 of 12 patients (42%) deemed unreconstructable on the preoperative CA. A mean of 13 minutes was required for IOA and an adequate study was obtained on the first attempt in 98 of 144 patients (86%). On postoperative review, more patent vessel segments but fewer segments with <50% stenosis were identified on the IOA compared to the CA.

CONCLUSIONS

Prebypass intraoperative arteriography facilitates selection of the optimal distal bypass target during infrageniculate revascularization and can result in initial limb salvage in select patients deemed unreconstructable by preoperative contrast arteriography.

Exogenously administered interleukin-10 decreases pulmonary neutrophil infiltration in a tumor necrosis factor-dependent murine model of acute visceral ischemia

INTRODUCTION

Visceral ischemia and reperfusion associated with thoracoabdominal aortic aneurysm (TAAA) repair results in lung injury, which appears to be mediated in part by proinflammatory cytokines. The purpose of this study was to determine the effect of exogenous administration of the antiinflammatory cytokine, recombinant human IL-10 (rhIL-10), on proinflammatory cytokine production (IL-6 and TNF alpha) and pulmonary neutrophil infiltration after acute visceral ischemia-reperfusion.

METHODS

Two hours before 25 minutes of supraceliac aortic occlusion, 80 C57BL/6 mice (20 to 22 g) received an intraperitoneal injection of rhIL-10 (0.2 microgram [n = 20], 2 micrograms [n = 20], 5 micrograms [n = 25], or 20 micrograms [n = 15]), and 16 mice received murine anti-IL-10 IgM 200 micrograms. Twenty-five additional mice underwent visceral ischemia-reperfusion without treatment (controls), and 16 mice underwent laparotomy without aortic occlusion (sham).

RESULTS

Pretreatment with exogenous rhIL-10 resulted in significant reductions in lung neutrophil infiltration with 0.2 microgram, 2 micrograms, and 5 micrograms per mouse of rhIL-10 compared with lung neutrophil levels in control mice that underwent acute visceral ischemia-reperfusion alone (p < 0.05). In addition, serum TNF alpha was detected in 50% of control mice and in 75% of mice that received murine anti-IL-10, but in none of the mice that received rhIL-10 (2 micrograms per mouse) or the mice that underwent sham operative procedures (p < 0.05 by chi 2 analysis).

CONCLUSION

Exogenous IL-10 limits pulmonary neutrophil recruitment and the appearance of TNF alpha in this model of visceral ischemia-reperfusion injury. Thus the use of exogenous IL-10 may offer a novel therapeutic approach to decrease the complications that are associated with TAAA repair.

Intraoperative autologous transfusion during elective infrarenal aortic reconstruction: a decision analysis model

PURPOSE

The use of intraoperative autologous transfusion devices expanded during the last decade as a result of the increased awareness of transfusion-associated complications. This study was designed to determine whether routine use of an intraoperative autologous transfusion device (Haemonetics Cell Saver [CS]) during elective infrarenal aortic reconstructions is cost-effective ($50,000/QALYs threshold).

METHODS

A decision analysis tree was constructed to model all of the complications that are associated with red blood cell replacement during aortic reconstructions for both abdominal aortic aneurysm (AAA) and aortoiliac occlusive disease (AIOD). It was assumed that a unit of CS return (CSR; 250 ml/unit) equaled a unit of packed red blood cells (PRBCs) and that all CS transfusions were necessary. Transfusion requirements (AAA:PRBC = 2.8 +/- 3.2 units, CSB = 3.7 +/- 3.2 units; AIOD:PRBC = 3.1 +/- 3.0 units, CSR = 2.1 +/- 1.7 units) were determined from retrospective review of all elective aortic reconstructions (AAA, N = 63; AIOD, N = 75) from Jan. 1991 to June 1995 in which the CS was used (82.1% of all reconstructions). Risk of allogenic transfusion-related complications (transfusion reaction, hepatitis B, hepatitis C, human immunodeficiency virus, human T-cell lymphotropic virus types I and II) and their associated treatment costs (expressed in dollars and quality-adjusted life years (QALYs) were obtained from the medical literature, institutional audit, and a consensus of physicians.

RESULTS

Routine use of the CS during elective infrarenal aortic reconstructions was not cost-effective in our practice. Use during reconstructions for AAA repairs cost $263.75 but added only 0.00218 QALYs, for a rate of $120,794/QALY. Use during reconstructions for AIOD was even more costly at $356.68 and provided even less benefit at 0.00062 QALYs, for a rate of $578,275/QALY. The sensitivity analyses determined that the routine use of the CS would be cost-effective in our practice only for AAA repairs if the incidence of hepatitis C were tenfold greater than the baseline assumption. The model determined that CS was cost-effective if the CSR exceed 5 units during reconstructions for AAA and 6 units during reconstructions for AIOD.

CONCLUSIONS

The routine use of the CS during elective infrarenal aortic reconstructions is not cost-effective. The use of the device should be reserved for a select group of aortic reconstructions, including those in which cost-effective salvage volumes are anticipated. Alternatively, the CS should be used as a reservoir and activated as a salvage device if significant bleeding is encountered.

Exogenous human recombinant interleukin-10 attenuates hindlimb ischemia-reperfusion injury

Proinflammatory cytokines have been found to mediate part of the local and distant organ injury after ischemia and reperfusion (I/R). The anti-inflammatory cytokine interleukin-10 (IL-10) inhibits both TNF-alpha and IL-1, and we hypothesized that exogenous human IL-10 may decrease lung and soleus muscle injury after hindlimb I/R. Male Sprague-Dawley rats were randomly assigned to I/R (n = 10); I/R+IL-10 (10 micrograms i.v., n = 10), SHAM (n = 4); or SHAM+IL-10 (10 micrograms i.v., n = 4). Bilateral hindlimb ischemia was produced by tourniquet occlusion for 4 hr and all animals were sacrificed after 4 hr of reperfusion or at comparable times for the SHAMs. Soleus muscle cellular injury was determined by uptake of 99Tc pyrophosphate while soleus muscle capillary permeability, and lung capillary permeability were assessed by uptake of 125I-labeled albumin. Soleus muscle and lung neutrophil infiltration were measured with the myeloperoxidase assay. Serum samples were assessed for TNF-alpha production with the WEHI bioassay. Hindlimb I/R caused significant soleus muscle cellular injury, soleus muscle capillary injury, lung capillary injury, and lung neutrophil infiltration, Pretreatment with exogenous IL-10 significantly reduced soleus muscle capillary permeability and also reduced soleus muscle cellular injury, but not to a statistically significant degree. IL-10 administration also reduced pulmonary capillary permeability despite significantly increased lung neutrophil infiltration. Elevated TNF-alpha levels were found in 66% (4/6) rats in the I/R group versus 30% (3/10) rats in the I/R+IL-10 group. Exogenous IL-10 attenuates both local and distant organ injury after hindlimb I/R potentially independent of neutrophil infiltration.

Intraoperative autologous transfusion during elective infrarenal aortic reconstruction

Intraoperative autologous transfusion devices have been purported to reduce allogenic transfusions and their associated complications. However, the value of their routine use during elective cardiovascular operations remains undefined. This study was designed to examine the efficacy of the Haemonetics Cell Saver (CS) during elective aortic reconstructions and identify predictors of clinically significant (> or = 500 cc) and cost-efficient (> or = 1250 cc) salvage volumes. The medical records of all patients undergoing elective infrarenal aortic reconstructions between January 1991 and June 1995 were retrospectively reviewed to determine blood loss, CS return, predictors of clinically significant/ cost-efficient CS returns, blood products transfused, and estimated cost per unit CS return. The CS was used for 138 (82.1%) of all reconstructions during the study period. Estimated blood loss (2127 +/- 1467 vs 1415 +/- 1047) and CS return (927 +/- 790 vs 515 +/- 408) were significantly greater in patients with aneurysms (AAA, N = 63) compared to those with aortoiliac occlusive disease (AIOD, N = 75). CS returns > or = 500 cc were common (79.4% AAA, 52.0% AIOD) and predictors of > or = 500 cc CS returns were large aneurysms (6.79 +/- 1.84 vs 5.72 +/- 0.71 cm) and male sex (82.0 vs 46.2%) in AAA patients and lower preoperative platelet counts (262 +/- 93 vs 311 +/- 113 K/mm3), concomitant renal revascularizations (20.5 vs 0%), and prolonged operative time (7.9 +/- 2.4 vs 6.9 +/- 2.1 hr) in AIOD patients. In contrast, CS returns > or = 1250 cc were relatively uncommon (28.6% AAA, 5.3% AIOD), and predictors of these CS returns were found only for AAA patients and included any concomitant vascular procedures (38.8 vs 15.6%) and the need for suprarenal aortic clamping (27.8 vs 6.7%). Despite the use of the CS, 73.8% of all patients required allogenic packed red blood cells with a mean of 3.0 +/- 3.1 units transfused in the perioperative period; no difference was seen between AAA and AIOD patients. The calculated cost for a unit of CS return was +128.77 for the AAA patients and +231.91 for the AIOD patients. Not using the CS and substituting the return with allogenic packed red blood cells would have saved +252.80 and +352.84 for the AAA and AIOD patients, respectively. Routine use of the CS during elective infrarenal aortic reconstructions is not cost efficient and should be abandoned. Use of the device should be reserved only for complex reconstruction.

Tissue plasminogen activator increases canine endothelial cell proliferation rate through a plasmin-independent, receptor-mediated mechanism

BACKGROUND

Tissue plasminogen activator (tPA) is elevated in cancer patients and is thought to promote tumor angiogenesis by facilitating endothelial cell migration through plasmin-mediated degradation of extracellular matrix. Due to the presence of an epidermal growth factor (EGF)-finger domain in the tPA A-chain and the existence of an endothelial cell (EC) receptor that binds this domain, it was hypothesized that tPA has a direct receptor-mediated effect on EC proliferation, independent of plasmin.

METHODS AND RESULTS

Using cultured canine ECs, tPA (7.25 microg/ml, approximately 107 nM) increased proliferation as much as 50 and 170% in the absence and presence of growth factors, respectively. tPA-induced increases in EC proliferation occurred independent of plasmin generation, as the plasmin inhibitor, aprotinin (10 microg/ml) did not inhibit tPA-induced proliferation. However, tPA-induced proliferation was inhibited dose-dependently to a maximum of 78% using a monoclonal antibody against the tPA EGF-finger domain. This antibody, known to inhibit tPA binding to its receptor, did not inhibit tPA-induced plasmin generation. To investigate the role of potential signal transduction pathways, ECs were exposed to lavendustin A, a tyrosine kinase inhibitor, at 33.5 microM (IC50 for basic fibroblast growth factor). Lavendustin A did not inhibit tPA-induced EC proliferation. However, Rp-cAMP, an inhibitor of cAMP-dependent kinases, specifically inhibited tPA-induced EC proliferation in a dose-dependent manner (IC50 = 50.5 microM). Pertussis toxin at maximal concentrations for this system (0.5 ng/ml) did not inhibit tPA-induced EC proliferation.

CONCLUSION

These results lend support to the hypothesis that tPA may have a direct receptor-mediated effect on EC proliferation and that this effect occurs independent of plasmin and may be dependent upon protein kinase A activity.

Visceral ischemia and organ dysfunction after thoracoabdominal aortic aneurysm repair. A clinical and cost analysis

OBJECTIVE

Repair of thoracoabdominal aortic aneurysms (TAAAs) is associated with significant postoperative morbidity and mortality. Reperfusion of acutely ischemic abdominal viscera in animals leads to release of multiple factors that cause local and distant organ damage, and similar phenomena occurring in humans after TAAA repair could contribute to the high morbidity/mortality and cost associated with this procedure.

METHODS

Twenty-nine patients undergoing elective TAAA repair were studied prospectively. Preoperative organ dysfunction and intraoperative risk factors (cross-clamp time, blood loss, operative time) were assessed and compared with postoperative organ dysfunction (defined as: pulmonary, positive pressure ventilation for > 7 days; renal, increase in serum creatinine > 2.0 mg/dL over baseline; hepatic, lactate dehydrogenase > 500 international units and total bilirubin > 3.0 mg/dL or serum transaminase level > 200 international units; hematopoietic, platelet count > 50 K or leukocyte count > 4.5 K, mortality, and costs.

RESULTS

No relationship between preoperative organ dysfunction, blood loss, or operative time and postoperative organ dysfunction or mortality was seen; however, cross-clamp times > 40 minutes were associated with a significantly greater incidence of pulmonary (59%), renal (47%), hepatic (35%), and hematopoietic (47%) dysfunction. In addition, multiple-organ dysfunction (> 2 organ systems) was more common after > 40 minutes of visceral ischemia and led to significantly greater overall hospital ($88,465 + $76,155 vs. $41,782 + $31,244) and intensive care unit ($26,726 + $28,256 vs. $11,234 + $12,146) costs (p < 0.01, Mann-Whitney U test). Mortality associated with leukopenia was 67% compared with 4% without leukopenia (p < 0.01).

CONCLUSION

Increasing durations of acute visceral ischemia led to significant multiple organ dysfunction after TAAA repair. Methods of limiting visceral ischemia or the systemic effects of visceral ischemia may decrease both the morbidity and mortality and the overall hospital cost associated with this procedure.

Effects of retroviral-mediated tissue plasminogen activator gene transfer and expression on adherence and proliferation of canine endothelial cells seeded onto expanded polytetrafluoroethylene

PURPOSE

Seeding prosthetic arterial grafts with genetically modified endothelial cells (ECs) has the potential to substantially improve graft function. However, preliminary applications suggest that grafts seeded with retrovirally transduced ECs yield a significantly lower percent surface coverage than those seeded with nontransduced ECs. The objective of this study was to test the hypothesis that canine ECs transduced with the human tissue plasminogen activator (tPA) gene would have a lower rate of adherence to pretreated expanded polytetrafluoroethylene (ePTFE) both in vitro and in vivo and that they would proliferate at a slower rate on pretreated ePTFE in vitro.

METHODS

Early passage ECs derived from canine external jugular vein were transduced with the retroviral MFG vector containing the gene for human tPA. ECs exposed to media alone served as controls. Iodine 125-labeled ECs were seeded in vitro onto ePTFE graft segments pretreated with canine whole blood, fibronectin (50 micrograms/ml), or media alone, and the percent of ECs adherent at 1 hour were determined (n = 3). Additional tPA-transduced and -nontransduced ECs were grown for 10 days on either fibronectin (50 micrograms/ml)-pretreated ePTFE wafers or tissue culture plastic pretreated with gelatin (1%) or fibronectin (50 micrograms/ml), and the EC proliferation rates were determined (n = 3). Furthermore, 125I-labeled ECs were seeded onto fibronectin (50 micrograms/ml)-pretreated ePTFE graft segments implanted as carotid and femoral artery interposition grafts (n = 3). The grafts were harvested after 1 hour, and the percent of ECs adherent was determined.

RESULTS

Human tPA was detected by immunohistochemical staining in 61% +/- 5% of the transduced ECs and was expressed at 35.4 +/- 12.9 ng/hr/10(6) cells. Fibronectin and whole blood pretreatment of the ePTFE grafts led to greater EC adherence in vitro than did media alone (90.9% +/- 5.3% vs 77.8% +/- 5.8% vs 4.7% +/- 1.1%, p < or = 0.05). No significant difference in the rates of adherence or proliferation was seen in vitro between the transduced and nontransduced ECs. No significant difference in proliferation was found for the transduced ECs on the three matrices tested in vitro. In contrast, adherence of the transduced ECs in vivo was significantly lower than that of nontransduced ECs (64.7% +/- 2.1% vs 73.7% +/- 4.1%, p < or = 0.05) 1 hour after implantation.

CONCLUSIONS

Lower rates of surface endothelialization by genetically modified ECs in vivo do not appear to be due to an impaired capacity to initially adhere or proliferate on the synthetic graft but may result from decreased adherence after exposure to in vivo hemodynamic forces.

Operative mortality rates after elective infrarenal aortic reconstructions

PURPOSE

This study was designed to test the hypothesis that cardiac complications (myocardial infarction, congestive heart failure, fatal arrhythmias) are no longer the leading cause of death after elective aortic reconstructions.

METHODS

The medical records of all elective infrarenal aortic reconstructions performed between January 1982 and June 1994 were retrospectively reviewed. All perioperative deaths were analyzed to determine the cause of death and were compared with a subset of 266 survivors to identify any associated preoperative or intraoperative factors.

RESULTS

Seven hundred twenty-two aortic reconstructions were performed for aneurysmal or occlusive disease, and there were 44 deaths (overall mortality rate of 6.1%). The mortality rate after aortic reconstruction alone was 4.9% and increased with the addition of renal (8.9%, p = 0.16) or lower extremity vascular procedures (15.8%, p = 0.01). Multisystem organ failure (MSOF) was the cause of death in 56.8%, of the patients (3.5% overall mortality rate) followed by cardiac events in 25% (1.5% overall mortality rate). Visceral organ dysfunction was the most common cause of MSOF leading to death in 14 patients (56.0%), and postoperative pneumonia was responsible for the fatal MSOF in nine patients (36.0%). Patient age, history of myocardial infarction/congestive heart failure, ejection fraction less than 50%, duration of operative time, and performance of additional procedures were associated with increased operative mortality rates by multivariate analysis.

CONCLUSIONS

MSOF, predominantly from visceral organ dysfunction, was the leading cause of death after elective infrarenal aortic reconstruction. The risk of MSOF and operative death increases with the complexity of the procedure and the number of comorbid conditions.

Selection of patients for renal artery repair using captopril testing

BACKGROUND

Prediction of improvement following surgical or radiologic intervention in patients thought to have renovascular hypertension (RVH) is often unreliable. Use of the angiotensin-converting enzyme inhibitor captopril in conjunction with measurement of peripheral renin levels or radioisotope renograms is thought to detect patients with functionally significant renal artery stenosis. However, it is unclear whether these tests can identify patients whose hypertension will significantly improve after renal artery repair.

PATIENTS AND METHODS

The records of 52 consecutive hypertensive patients undergoing captopril studies followed by renal artery repair were reviewed. All patients had either renal artery stenosis > 75% or renal artery occlusion. Preprocedure evaluation included a captopril challenge test (measurement of peripheral renin levels after captopril ingestion) (n = 12) or a captopril renogram (determination of renal blood flow and glomerular filtration rate before and after captopril administration) (n = 40). Either renal artery bypass/nephrectomy (n = 41) or balloon angioplasty (n = 11) was done in all patients (18 bilateral/34 unilateral). No periprocedural deaths occurred. All surgically placed bypass grafts were shown to be patent by contrast or carbon dioxide arteriography before hospital discharge.

RESULTS

Preprocedure captopril tests were positive (suggestive of RVH) in 39 patients (75%) and negative in 13 (25%). All patients with positive captopril tests had improvement in their RVH after intervention (17 cured, 22 improved) while 8 of 13 patients with negative captopril tests had no improvement in blood pressure control. Four of five false-negative tests were associated with a unilateral total renal artery occlusion, making detection of a postcaptopril effect impossible. If these 4 patients are excluded from analysis, preprocedure captopril testing was 98% accurate in predicting postprocedure outcome.

CONCLUSIONS

Preprocedure captopril testing permits extremely accurate selection of patients with renal artery stenosis who will benefit from renal artery repair.

Hormonal profiles in a canine model of the brain-dead organ donor

PURPOSE

The aim of the present study was to determine the effect of brain death on the circulating hormone levels.

METHODS

Serum total thyroxine (TT4), total 3,3,5' triiodothyronine (TT3), free thyroxine (FT4), free 3,3,5' triiodothyronine (FT3), reverse 3,3',5' triiodothyronine (RT3) and plasma cortisol (CORT), norepinephrine (NE), epinephrine (EPI), dopamine, insulin (INS), and glucagon (GLUC) concentrations were measured before and for 5 hours after the maintenance of brain death (BD, n = 8), sham-brain death induction (SHAM, n = 3), and the operative procedure alone (time control, n = 3). Brain death in the canine model was induced by increasing and maintaining intracranial pressure above systolic arterial pressure.

RESULTS

Brain death led to a persistent, significant decrease in mean arterial pressure (121 +/- 6 v 40 +/- 4 mm Hg at 5 hours). A significant decrease in the TT4, TT3, FT4, and FT3 concentrations was seen during the experiment for all three groups with the exception of TT4 in the SHAM group; no significant difference was found among the three groups for any of the time points. RT3 was found to increase after the induction of brain death in the BD (n = 5) group. The CORT levels in the BD group were significantly less than the other two groups for all time points 30 minutes after the induction of brain death. The mean 30- to 300-minute plasma NE and EPI levels in the SHAM group were statistically greater than the BD group. The plasma glucose in the BD group was maintained between 60 and 140 mg/dL whereas the trends of the INS/glucose and GLUC/glucose ratios in the BD group were appropriate for the plasma glucose level.

CONCLUSIONS

The operative procedure alone led to the decrease in the plasma thyroid hormone levels. The inability of the BD group to increase plasma CORT, NE, and EPI may contribute to the hemodynamic deterioration and eventual somatic death.

Myocardial contractility in a canine model of the brain-dead organ donor

OBJECTIVE

To test the hypothesis that the induction and maintenance of brain death leads to a decrease in myocardial contractility.

DESIGN

Prospective, randomized, controlled trial.

SETTING

Laboratory at a large, university-affiliated medical center.

SUBJECTS

Sixteen adult, male, mongrel dogs weighing 15 to 25 kg.

INTERVENTIONS

Myocardial contractile performance was evaluated after the induction of either brain death (n = 8), sham brain death (n = 4), or an operative procedure serving as a time control (n = 4). Brain death was induced by increasing and maintaining intracranial pressure above arterial systolic pressure. Contractile performance was determined with sonomicrometers arrayed to measure wall thickness in the anterior and posterolateral left ventricle. Brief aortic constrictions enabled derivation of the end-systolic pressure-thickness relationship, a relatively load-insensitive index of contractility.

MEASUREMENTS AND MAIN RESULTS

No statistically significant hemodynamic differences were detected between the sham and time control groups. The brain-dead group displayed marked hemodynamic deterioration; 4 hrs after brain death was induced, mean arterial blood pressure, cardiac index, and the peak positive first derivative of left ventricular pressure were 63%, 35%, and 53% lower, respectively, than those values in the two control groups. However, the slope of the end systolic pressure-thickness relationship remained at 92 +/- 12% of baseline levels 4 hrs after brain death was induced and was not significantly different from the two control groups.

CONCLUSIONS

The hemodynamic deterioration after the induction of brain death could not be attributed to a decrease of myocardial contractility as measured by the end systolic pressure-thickness relationship.

Plasma profiles of IL-6-like and TNF-like activities in brain-dead dogs

The progression to somatic death after brain death is poorly understood. The role of tumor necrosis factor (TNF) and interleukin-6 (IL-6) in this progression is unknown. TNF-like and IL-6-like plasma activities were assayed in a canine model of brain death in the presence and absence of a lipopolysaccharide (LPS) challenge (0.22 micrograms/kg). Bioassays for TNF-like and IL-6-like activities used WEHI and B9 cell lines, respectively. Brain death was induced by elevating and maintaining intracranial pressure above systolic arterial pressure. Anesthesia and the operative procedure did not cause a significant increase of either cytokine. Brain death (n = 8) itself did not cause a significant elevation of either cytokine compared with the sham brain-death control (n = 6) despite a significant decrease in mean arterial pressure (35 +/- 3 vs. 115 +/- 5 mmHg at 5 h). The brain-dead group treated with LPS (n = 6) responded with a significant elevation in IL-6-like and TNF-like activities compared with the vehicle-treated group. The rise of IL-6-like activity in response to LPS was greater in the brain-dead group than in the sham brain-dead group (n = 3); no significant difference was noted for the TNF-like response. We conclude that the progression to somatic death after brain death cannot be explained by increases in circulating TNF-like or IL-6-like activities.(ABSTRACT TRUNCATED AT 250 WORDS)

Elevated blood ketone and glucagon levels cannot account for 1,3-butanediol induced cerebral protection in the Levine rat

1,3-Butanediol is an ethanol dimer that induces systemic ketosis. It has previously been shown to increase hypoxic survival time and reduce neurologic deficit in several experimental preparations. The aim of this study was to determine if the mechanism of 1,3-butanediol-induced cerebral protection was elevation of blood ketone levels, blood glucagon levels, or both. Blood beta-hydroxybutyrate levels, glucagon levels, or both produced by a previously reported protective dose of 1,3-butanediol (47 mmol/kg) were simulated by direct i.v. infusion of the ketone beta-hydroxybutyrate and glucagon separately and in combination, and the effect on hypoxic survival time in instrumented Levine rats (unilateral carotid ligation and hypoxic exposure) was determined. To test if the mechanism was a direct or osmotic effect of the alcohol, an equimolar dose of ethanol (47 mmol/kg) was administered and the effect on hypoxic survival time was compared with that produced by 1,3-butanediol. As in previous studies, 1,3-butanediol significantly increased hypoxic survival time (241% of control, Scheffe p less than 0.05). Various doses of beta-hydroxybutyrate and glucagon were infused to approximate the blood levels of beta-hydroxybutyrate and glucagon produced by a protective dose of 1,3-butanediol. Although beta-hydroxybutyrate or glucagon infusions produced blood levels of these substances that were comparable with those produced by administering butanediol, they failed to prolong hypoxic survival time as long as 1,3-butanediol. No correlation was detected between hypoxic survival time and blood levels of beta-hydroxybutyrate, glucagon, insulin, or glucose. An equimolar dose of ethanol did not significantly increase hypoxic survival time.(ABSTRACT TRUNCATED AT 250 WORDS)