Deposition pattern of monocytes and fatty streak development in hypercholesterolemic rabbits.

To further characterize the role of monocytes in atherogenesis, we studied the influence of a qualitatively, well-defined hemodynamic flow field on the deposition pattern of monocytes in the thoracic aorta of normal (N, n = 6) and hypercholesterolemic (H, n = 10) rabbits. Pairs of H rabbits were sacrificed after 1, 2, 4, 7 and 10 weeks of cholesterol feeding. Complete deposition patterns of adherent cells were quantified over 500 mm2 of aortic endothelium around the lesion-susceptible intercostal orifices using an en face light microscopic technique. Adherent cells were almost exclusively monocytes by morphological criteria and non-specific esterase staining. The mean density of adherent cells in normal rabbits was 1.28 +/- 1.21 (S.D.) per mm2 of endothelium and increased nearly 5-fold by 7 weeks of cholesterol feeding. High local densities of adherent monocytes (up to 34 cells/mm2) were noted over early fatty lesions present in one 4 week and all 7 and 10 week H rabbits. Adherent cell densities near intercostal orifices prior to lesion formation were approximately 50% greater than in non-orifice regions in both the normal and the 1 and 2 week H rabbit groups. These differences were statistically significant at P < 0.05 by ANOVA. We conclude that preferred adherence of monocytes occurs around intercostal orifices in normolipidemic and early cholesterol-fed rabbits before lesions develop at these lesion-prone sites. Monocyte deposition appears to be governed not only by the arterial flow field but also by cholesterol feeding since higher numbers of adherent monocytes were found on both early fatty streaks and nonlesioned endothelium in rabbits fed cholesterol for longer than 4 weeks.

The respective racial and ethnic diversity of US pediatricians and American children.

BACKGROUND: Much effort has been directed toward increasing the training of physicians from underrepresented minority groups, yet few direct comparisons have examined the diversity of the racial/ethnic backgrounds of the physicians relative to the patient populations they serve, either currently or into the future. This has been particularly true in the case of pediatrics, in which little information has emerged regarding the racial/ethnic backgrounds of pediatricians, yet evidence points to ever-growing diversity in the US child population. OBJECTIVE: We embarked on a comparative analysis to examine trends in the racial and ethnic composition of pediatricians vis-a-vis the patient population they serve, America's infants, children, adolescents, and young adults. METHODS: Data on US pediatricians sorted by racial/ethnic group came from Association of American Medical Colleges distribution data and is based on the cohort of pediatricians graduating from US medical schools between 1983 and 1989 extrapolated to the total number of pediatricians actively practicing in 1996. Data on the demographic diversity of the US child population came from the US Census Bureau. We derived pediatrician-to-child population ratios (PCPRs) specific to racial/ethnic groups to measure comparative diversity between and among groups. RESULTS: Our results show that the black PCPR, currently less than one third of the white PCPR, will fall from 14.3 pediatricians per 100 000 children in 1996 to 12 by 2025. The Hispanic PCPR will fall from 16.9 in 1996 to 9.2 in 2025. The American Indian/Alaska Native PCPR will drop from 7.8 in 1996 to 6.5 by the year 2025. The PCPR specific to the Asian/Pacific Islander group will decline from 52.9 in 1996 to 26.1 in 2025. For whites, the PCPR will increase from 47.8 to 54.2 during this period. For 1996, each of the 5 PCPRs is significantly different from the comparison ratio. The same is true for 2025. For the time trend comparison (between 1996 and 2025), there is a significant difference for each ratio except for American Indian/Alaska Native. CONCLUSION: The racial and ethnic makeup of the US child population is currently far more diverse than that of the pediatricians who provide their health care services. If child population demographic projections hold true, and no substantial shifts transpire in the composition of the pediatric workforce, the disparities will increase substantially by the year 2025.

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.

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.

Angiography with carbon dioxide (CO2).

CO2 possesses many advantages over conventional iodinated contrast agents used for arteriography. It is nonallergic and lacks renal toxicity. Its unique properties permit use of smaller catheters in diagnostic and therapeutic angiographic procedures, allow optimal vascular imaging of various neoplasm, assist in detection of occult gastrointestinal bleeding, and facilitate TIPS procedures. With digital subtraction techniques and stacking programs, CO2 arteriography is as accurate as iodinated contrast studies in most patients and thus is the preferred arterial imaging technique in patients with contrast allergy and renal insufficiency. CO2 is also extremely inexpensive compared with available contrast agents. Understanding of the effects of buoyancy and compressibility is necessary for safe, controlled delivery of CO2 during arteriography, but only rare complications have occurred in our large experience with CO2 angiography. Thus, use of CO2 as an arterial contrast agent significantly expands the safety and utility of arterial imaging in patients with peripheral vascular disease.

Forward-looking intravascular ultrasonography: in vitro imaging of normal and atherosclerotic human arteries.

Inadequate guidance of angioplasty devices limits the endoluminal treatment of high grade atherosclerotic stenoses and total occlusions. Conventional intraluminal ultrasound systems (IVUS) enable lateral cross-sectional imaging of tomographic sections of the vessel wall, but do not offer imaging in front of the catheter. This study describes our initial experience with a forward-looking intravascular ultrasound (FL-IVUS) system (Echoeye, EchoCath, Inc., Princeton, NJ). The acoustic beam from a 25.5 MHz piezoelectric transducer on a 7.5 Fr catheter is mechanically rotated in a forward-looking spiral fashion at 300 cycles/second. Sixty-four axially aligned, cross-sectional, real time images are obtained from a truncated, 60 degree conical volume located 5 to 10 mm from the catheter tip. Luminal dimensions (n = 51) of human cadaveric femoral arteries (cast in agar and submerged in saline) measured by the FL-IVUS were compared to histologic cross-sections of the vessel with a correlation of r = 0.92. FL-IVUS accurately imaged the narrowing lumen in front of total occlusions and the geometry at vessel branches, and identified the location of lesions and the shape and morphology of vessel wall thickness. The 7.5 Fr FL-IVUS over-estimated luminal dimensions in vessels larger than 5 mm. We conclude that FL-IVUS imaging shows promise as a new, accurate method for identifying and characterizing high grade atherosclerotic stenoses and total occlusions, and expands the current capabilities of conventional IVUS systems.

Carotid intervention prior to or during coronary artery bypass grafting. When is it necessary?

Management of patients with advanced atherosclerosis involving the extra-cranial carotid and coronary arteries should be individualized based on symptoms and disease severity. A liberal policy to identify high-grade carotid stenosis using duplex ultrasound testing prior to coronary revascularization is recommended. Carotid intervention is efficacious for stroke reduction in patients with severe (>70% diameter reduction), bilateral internal carotid artery disease, especially if testing indicates abnormal cerebral perfusion via the circle of Willis. The morbidity of a combined carotid-coronary revascularization procedure should be less than 5%, but higher stroke and death rates can be expected in urgent cases with recent hemispheric symptoms. Patients with symptomatic >50% internal carotid artery stenosis should be considered for carotid endarterectomy at the time of coronary revascularization. Carotid angioplasty with cerebral protection is also an appropriate option in "high-risk" cardiac patients, especially in vascular centers with expertise and experience in performing this procedure. A policy of carotid endarterectomy prior to coronary bypass grafting is justified only in patients with stable coronary disease, good ejection fraction, and is best-performed using regional anesthesia.

Hemodynamic consequences of stenosis remodeling during coronary angioplasty.

Quantitative hemodynamic assessment during various endovascular interventions including balloon angioplasty is lacking. Translesional pressure drops measured by angioplasty catheters can cause flow blockage and thus lead to inaccurate estimates of preintervention and postintervention flow rates. A new analytical model of the flow rate-pressure drop relation across vascular stenoses is utilized that is nonlinear yet relatively simple in principle, easily applicable in vivo, and compatible with the presence of catheters. The model incorporates in vitro experimental evidence, angiographic data on the dimensions and shapes of coronary arterial stenoses before and after balloon angioplasty, reported translesional pressure gradients, and measurements of coronary flow reserve. Reasonable estimates of mean coronary artery flow rates and translesional pressure drops in the absence of angioplasty catheters are obtained. Prior to angioplasty significant flow restriction across a 68% diameter stenosis exists during hyperemic flow conditions. Following successful balloon dilation, increased minimal cross-sectional area (residual 40% diameter stenosis) results in an improved flow rate-pressure drop relation. Despite minimal flow restriction during hyperemic conditions following angioplasty remodeling, residual luminal constriction leads to elevated wall shear stress levels within the entry region of the stenosis. The flow analysis described may be of clinical utility in evaluating the hemodynamic significance of the anatomic severity of stenoses in coronary and peripheral arteries before and after endovascular therapeutic interventions.

The efficacy of carotid endarterectomy: a vascular surgery perspective reducing hospital stay.

Contemporary vascular management results in significant reduction of stroke risk. Carotid endarterectomy is both safe and effective, often with a 1 or 2-day hospital stay. State-of-the-art nursing practice is key to the efficacy of patient management.

Flow rate-pressure drop relation in coronary angioplasty: catheter obstruction effect.

Quantitative methods to measure the hemodynamic consequences of various endovascular interventions including balloon angioplasty are limited. Catheters measuring translesional pressure drops during balloon angioplasty procedures can cause flow blockage and thus inaccurate estimates of pre- and post-intervention flow rates. The purpose of this investigation was to examine the influence of the presence and size of an angioplasty catheter on measured mean pressure gradients across human coronary artery stenoses. Analytical flow modeling and in vitro experimental evidence, coupled with angiographic data on the dimensions and shape of stenotic vessel segments before and after angioplasty, indicated significant flow blockage effects with the catheter present.

Detection and evaluation of aerodigestive tract injuries caused by cervical and transmediastinal gunshot wounds.

BACKGROUND: Aerodigestive tract penetrations occurring with gunshot wounds to the neck and thorax are uncommon but are frequently associated with multiple organ injury and contribute to significant morbidity. METHODS: The selective management strategy used at our institution for suspected aerodigestive tract involvement with cervical, thoracic inlet, and transmediastinal gunshot wounds is reviewed with reference to eight clinical cases from 1989 to 1995. RESULTS: Seven pharyngoesophageal and four laryngotracheal injuries are described with three patients sustaining combined aerodigestive organ wounds. Associated injuries occurred in seven of the eight cases. Diagnosis of aerodigestive tract penetrations were made by triple endoscopy in five patients, by contrast esophagography in one case, and at operation for associated injuries in two patients. No injuries were missed during endoscopy or contrast studies. Two patients suffered complications including delayed recognition of an esophageal injury and pneumonia in one case and dehiscence of a distal esophageal repair in another. An associated vascular injury resulted in a single death in the series. CONCLUSIONS: A high index of suspicion must be maintained for aerodigestive tract involvement with cervicothoracic gunshot wounds. We advocate operative endoscopic inspection during emergent exploration in unstable patients or arteriography with endoscopy in stable patients. Adjunctive contrast pharyngoesophagography is performed to confirm equivocal endoscopic findings, evaluate the extent of leak, or completely exclude injury.

Fluid dynamic study in a femoral artery branch casting of man with upstream main lumen curvature for steady flow.

An in-vitro, steady flow investigation was conducted in a hollow, transparent vascular replica of the profunda femoris branch of man for a range of physiological flow conditions. The replica casting tested was obtained from a human cadaver and indicated some plaque formation along the main lumen and branch. The flow visualization observations and measured pressure distributions indicated the highly three-dimensional flow characteristics with arterial curvature and branching, and the important role of centrifugal effects in fluid transport mechanisms.

Flow measurements in a human femoral artery model with reverse lumen curvature.

Flow visualization and wall pressure measurements were made in a smooth reverse curvature model that conformed to the gentle "s" shape of a left femoral artery angiogram of a patient in a clinical trial. Observed lesion localization at the inner (lesser) curvatures appeared to be associated with secondary flows in the wall vicinity directed toward the inner curvatures that tended to reverse direction in the flow entering the reverse curvature region. Moderate flow resistance increases of about 20 percent above the Poiseuille flow relation were found at the higher physiological Reynolds numbers Re above about 600-700 and thus Dean numbers for steady flow. For pulsatile flow simulation, flow resistances did not increase up to the largest Re of 470 tested. Apparently, the large variations in velocity during the cardiac cycle disrupted the stronger secondary flow patterns observed at the higher Reynolds numbers for steady flow.

Fluid particle motion and Lagrangian velocities for pulsatile flow through a femoral artery branch model.

A flow visualization study using selective dye injection and frame by frame analysis of a movie provided qualitative and quantitative data on the motion of marked fluid particles in a 60 degree artery branch model for simulation of physiological femoral artery flow. Physical flow features observed included jetting of the branch flow into the main lumen during the brief reverse flow period, flow separation along the main lumen wall during the near zero flow phase of diastole when the core flow was in the downstream direction, and inference of flow separation conditions along the wall opposite the branch later in systole at higher branch flow ratios. There were many similarities between dye particle motions in pulsatile flow and the comparative steady flow observations.

Metastasis of an intracranial germinoma through a ventriculoperitoneal shunt: recurrence as a yolk-sac tumor.

Extraneural metastases of intracranial germinomas, although infrequent, are associated with a generally poor prognosis despite the high radiosensitivity of localized primary tumors. Ventriculoperitoneal shunts have been implicated in facilitating metastatic spread of primary intracranial germinomas. We present a case of a successfully irradiated suprasellar germinoma recurring after 13 months as an intra-abdominal yolk-sac tumor in a young man. The tumor was eradicated with a combination of systemic chemotherapy and local irradiation, with no residual viable tumor cells confirmed at final surgical extirpation. The role of cerebrospinal fluid (CSF) shunts in metastases, mixed germ-cell tumor histology, and tumor markers in recurrences as well as radiation doses and volumes for treating primary tumors are discussed. Systemic chemotherapy may be utilized as prophylaxis against shunt metastases when CSF drainage is necessary.

Intraoperative ultrasound assessment in management of complex pancreatic pseudocysts.

Preoperative imaging studies and operative inspection may provide insufficient information to appropriately manage certain complex pancreatic pseudocysts. Intraoperative ultrasound accurately identifies and localizes peripancreatic fluid collections, cyst wall thickness, parenchymal and ductal anatomy, and relationships to adjacent visceral and vascular structures. Adjunctive use of intraoperative ultrasonography altered the surgical management in the clinical case described herein and is advocated for assessment of problematic pancreatic pseudocysts.

Physiological flow simulation in residual human stenoses after coronary angioplasty.

To evaluate the local hemodynamic implications of coronary artery balloon angioplasty, computational fluid dynamics (CFD) was applied in a group of patients previously reported by [Wilson et al. (1988), 77, pp. 873-885] with representative stenosis geometry post-angioplasty and with measured values of coronary flow reserve returning to a normal range (3.6 +/- 0.3). During undisturbed flow in the absence of diagnostic catheter sensors within the lesions, the computed mean pressure drop delta p was only about 1 mmHg at basal flow, and increased moderately to about 8 mmHg for hyperemic flow. Corresponding elevated levels of mean wall shear stress in the midthroat region of the residual stenoses, which are common after angioplasty procedures, increased from about 60 to 290 dynes/cm2 during hyperemia. The computations (Ree approximately equal to 100-400; alpha e = 2.25) indicated that the pulsatile flow field was principally quasi-steady during the cardiac cycle, but there was phase lag in the pressure drop-mean velocity (delta p - u) relation. Time-averaged pressure drop values, delta p, were about 20 percent higher than calculated pressure drop values, delta ps, for steady flow, similar to previous in vitro measurements by Cho et al. (1983). In the throat region, viscous effects were confined to the near-wall region, and entrance effects were evident during the cardiac cycle. Proximal to the lesion, velocity profiles deviated from parabolic shape at lower velocities during the cardiac cycle. The flow field was very complex in the oscillatory separated flow reattachment region in the distal vessel where pressure recovery occurred. These results may also serve as a useful reference against catheter-measured pressure drops and velocity ratios (hemodynamic endpoints) and arteriographic (anatomic) endpoints post-angioplasty. Some comparisons to previous studies of flow through stenoses models are also shown for perspective purposes.

Catheter obstruction effect on pulsatile flow rate--pressure drop during coronary angioplasty.

The coupling of computational hemodynamics to measured translesional mean pressure gradients with an angioplasty catheter in human coronary stenoses was evaluated. A narrowed flow cross section with the catheter present effectively introduced a tighter stenosis than the enlarged residual stenoses after balloon angioplasty; thus elevating the pressure gradient and reducing blood flow during the measurements. For resting conditions with the catheter present, flow was believed to be about 40 percent of normal basal flow in the absence of the catheter, and for hyperemia, about 20 percent of elevated flow in the patient group. The computations indicated that the velocity field was viscous dominated and quasi-steady with negligible phase lag in the delta p(t)-u(t) relation during the cardiac cycle at the lower hydraulic Reynolds numbers and frequency parameter. Hemodynamic interactions with smaller catheter-based pressure sensors evolving in clinical use require subsequent study since artifactually elevated translesional pressure gradients can occur during measurements with current angioplasty catheters.

Magnetic resonance angiography is an accurate imaging adjunct to duplex ultrasound scan in patient selection for carotid endarterectomy.

PURPOSE: The purpose of this study was to evaluate the accuracy of magnetic resonance angiography (MRA) for categorizing the severity of carotid disease relative to duplex ultrasound scan and cerebral contrast arteriography (CA) to determine if MRA imaging could replace the need for cerebral angiography in cases of indeterminate or inadequate duplex scan imaging. METHODS: Seventy-four carotid bifurcations in 40 patients undergoing 45 carotid endarterectomies from 1996 to 1998 were imaged with duplex ultrasound scan; MRA (two-dimensional neck and three-dimensional intracranial, time-of-flight technique); and biplanar, digital subtraction cerebral arteriography. Studies were blindly reviewed by one reader who used established threshold velocity criteria for the duplex scan and the North American Symptomatic Carotid Endarterectomy Trial method for MRA and CA to determine the percentage of diameter reduction of the internal carotid artery (ICA). Disease severity was grouped into four categories (< 50%, 50%-74%, 75%-99% stenosis and occlusion), and the results of MRA and duplex ultrasound scan were compared with CA. RESULTS: Sensitivity, specificity, positive predictive value, and negative predictive value for detection of > 50% ICA stenosis were 100%, 96%, 98%, and 100% for MRA and 100%, 72%, 88%, and 100% for duplex ultrasound scan, respectively; similarly, for detection of > 75% ICA stenosis values were 100%, 77%, 76%, and 100% for MRA and 90%, 74%, 72%, and 91% for duplex ultrasound scan, respectively. Both MRA and duplex ultrasound scan accurately differentiated all cases of > 95% stenosis (n = 7) from occlusion (n = 4). Short length ICA flow gaps were present on MRA in all cases of 75% to 99% stenosis and one half of cases of CA-defined 50% to 74% stenosis. In patients with 50% to 74% stenosis, the mean angiographic stenosis was significantly greater when a flow gap was present on MRA (64% +/- 6%) versus no flow gap (57% +/- 7%) (P =.04). There was overall agreement among duplex ultrasound scan, MRA, and CA in 73% of carotids imaged. Of the 24% discordant results between MRA and duplex ultrasound scan, MRA correctly predicted disease severity in all cases, and inaccurate duplex ultrasound scan results were due to overestimation in 83% of cases. The operative plan was altered by CA findings in only one patient (2%) after duplex ultrasound scan and MRA. CONCLUSIONS: MRA can accurately categorize the severity of carotid occlusive disease. Duplex ultrasound scan facilitates patient selection for carotid endarterectomy in most cases, but adjunct use of MRA improves diagnostic accuracy for > 75% stenoses and may obviate the need for cerebral arteriography when duplex scan results are inconclusive or demonstrate borderline disease severity.

Use of rifampin-soaked gelatin-sealed polyester grafts for in situ treatment of primary aortic and vascular prosthetic infections.

BACKGROUND: In situ treatment of artery/graft infection has distinct advantages compared to vessel excision and extra-anatomic bypass procedures. Based on animal studies of a rifampin-soaked, gelatin-impregnated polyester graft that demonstrated prolonged in vivo antibacterial activity, this antibiotic-bonded graft was used selectively in patients for in situ treatment of low-grade Gram-positive prosthetic graft infections or primary aortic infections not amenable to excision and ex situ bypass. METHODS: In a 5-year period (1995-1999), 27 patients with prosthetic graft infection (aortofemoral, n = 18, femorofemoral, n = 3; axillofemoral, n = 1) or primary aortic infection (mycotic aneurysm, n = 3; infected AAA, n = 2) underwent excision of the infected vessel and in situ replacement with a rifampin soaked (45-60 mg/ml for 15 min) gelatin-impregnated polyester graft. All prosthetic graft infections were low grade in nature, caused Gram-positive bacteria (Staphylococcus epidermidis, 16; Staphylococcus aureus, 5; Streptococcus, 1), and were treated electively. Patients with mycotic aortic aneurysm presented with sepsis and underwent urgent or emergent surgery. RESULTS: Two (8%) patients died-1 as a result of a ruptured Salmonella mycotic aortic aneurysm and the other from methicillin-resistant S. aureus infection following deep vein replacement of an in situ replaced femorofemoral graft. No amputations or late deaths as the result of vascular infection occurred in the 25 surviving patients. Two patients developed recurrent infection caused by a rifampin-resistant S. epidermidis in a replaced aortofemoral graft limb and were successfully treated with graft excision and in situ autogenous vein replacement. Eighteen patients remain alive and clinically free of infection after a mean follow-up interval of 17 months. CONCLUSIONS: In situ replacement treatment using a rifampin-bonded prosthetic graft for low-grade staphylococcal arterial infection was safe, durable, and associated with eradication of clinical signs of infection. Failure of this therapy was the result of virulent and antibiotic-resistant bacterial strains.