Simulation case rehearsals for carotid artery stenting.

A case series of 5 patients is presented assessing the utility of simulation case rehearsals of individual patients for carotid artery stenting on an endovascular simulator. Simulated and operative device dimensions were similar. Results of subjective surveys indicated that face and content validity were excellent. The simulations predicted difficulty with vessel cannulation, however had difficulty predicting post-stent changes in bifurcation angulation. Our experience suggests that it may be feasible to use patient-specific CTA-derived data in the creation of a realistic case rehearsal simulation. The overall utility of this concept, including cost-benefit analysis, has yet to be determined.

Total parenteral nutrition-induced changes in gut mucosal function: atrophy alone is not the issue.

BACKGROUND: Total parenteral nutrition (TPN) has been implicated in gut atrophy and breakdown of barrier function leading to bacterial translocation (BT) in animals. BT during TPN, however, is not found consistently, and it has therefore been suggested that macromolecular permeability may occur independently of BT during TPN. METHODS: Male Sprague-Dawley rats were administered isocaloric standard TPN enterally, parenterally, or split equally between the two routes or allowed food ad lib. A second group of rats was administered isocaloric TPN with and without 4% lipids, and changes in gut barrier function were assessed by measuring lactulose permeability. RESULTS: Rats receiving TPN both enterally and parenterally maintained histologic intestinal structure to the same degree as rats fed enterally and those allowed food. Although parenteral feeding led to significant gut atrophy and cecal bacterial overgrowth, BT was not increased. Gut permeability to lactulose, however, was increased significantly in the TPN groups. Lipid content did not affect outcome. CONCLUSIONS: These results suggest that gut atrophy, BT, and permeability to macromolecules are not necessarily related. Gut-origin septic states during TPN or trauma may be caused by an increased escape of macromolecules from the gut, and BT may be an end result rather than a primary cause of such septic episodes.

Are prophylactic antibiotics required for elective laparoscopic cholecystectomy?

BACKGROUND: Some clinicians administer prophylactic antibiotics routinely before laparoscopic cholecystectomy, and the results of some of the studies in the literature support this practice. We conducted a prospective randomized trial to determine whether administration of prophylactic antibiotics is necessary during routine laparoscopic cholecystectomy in low-risk patients. STUDY DESIGN: Two hundred fifty patients without evidence of acute inflammation, common duct stones, or other indications for antibiotics were randomized to receive three perioperative doses of cefazolin or no prophylaxis and followed up for complications up to 30 days postoperatively. The primary end point was the occurrence of a major infectious complication, defined as that causing a systemic response, delaying discharge, or leading to readmission. Minor infectious problems were also noted, defined as those causing local symptoms only. RESULTS: One hundred twenty-eight patients were randomized to receive prophylactic antibiotics (PA group), 122 to receive none (NONE group; two patients in this group were actually given preoperative antibiotics). Only one major complication occurred (in a patient in the NONE group), an abscess in the presence of a bile leak, despite the administration of antibiotics when the leak was discovered several days before infectious problems arose. There were four minor problems: two lower urinary tract infections and one superficial wound infection in a NONE patient and one urinary tract infection in a PA patient (not significant); all were easily managed. The prophylactic antibiotics did not sterilize the bile, and infectious complications were not associated with weight, inflammation found at the time of operation, reported stone or bile spill-age, or conversion to open operation. CONCLUSIONS: Prophylactic antibiotics are not necessary for elective laparoscopic cholecystectomy in low-risk patients.

Irradiation for intimal hyperplasia: implications for peripheral arterial bypass.

Irradiation has been shown to inhibit postangioplasty intimal hyperplasia ("restenosis") in unbranched tubes. It seems likely that irradiation will similarly be able to inhibit intimal hyperplasia after a surgical anastomosis at a biochemical and cellular level, but whether it will produce a clinically relevant or even clinically detectable difference is unproved. One possibility is that no clinical effect may occur; the search for a "cure" for intimal hyperplasia has been long and, as yet, unsuccessful. On the other hand, if a strong effect without insurmountable logistical problems could be produced, one major cause of bypass graft failure would be preventable. Not only would the incidence of late graft occlusion, need for reoperation, and limb loss be reduced, but, if patency of prosthetics could be sufficiently improved, the initial operation could be made much easier, faster, and perhaps safer.

A rational screening and treatment strategy based on the electrocardiogram alone for suspected cardiac contusion.

The charts of 71 patients admitted to one teaching institution over a 4-year period with a primary or secondary diagnosis of "rule out cardiac contusion" and of another 62 admitted to a second institution with more severe injuries and suspicion of cardiac contusion were reviewed to determine if mortality or morbidity would have occurred if all patients with normal electrocardiograms (EKGs) in the emergency department (ED) were discharged (or admitted to unmonitored beds for other injuries). Only 13 patients developed cardiac problems: two elderly patients died in the ED, while the others experienced arrhythmias or, less commonly, pump failure requiring treatment or observation. All 13 had EKG changes present while still undergoing evaluation in the ED: 11 had a specific problem on arrival, 1 developed a problem while still being evaluated in the ED, and the 13th had what was probably an iatrogenic problem. Importantly, 5 of 12 patients had normal creatine phosphokinase-MB fractions, and 5 of 9 had normal echocardiograms. No patient with a normal EKG had subsequent cardiac problems. Operative intervention for other injuries was necessary in 26 patients overall, and there was no cardiac morbidity. We conclude that had the EKG been used as the sole screening tool, approximately 25% of these patients could have been discharged from the ED without missing problems. In addition, management would have been greatly simplified, and the hospital would have realized substantial savings, both in terms of direct costs and in the freeing of valuable and scarce resources.

Low-dose enteral feeding is beneficial during total parenteral nutrition.

BACKGROUND: Enteral support is the preferred feeding route for stressed patients due in part to the provision of gut-specific fuels. In those patients who must be maintained parenterally, small amounts of enteral stimulation might blunt gut atrophy and lead to improvement in host defense mechanisms decreasing macromolecular and/or bacterial translocation (BT). METHODS: Forty-eight rats were infused with TPN for 9 days, and were randomized to receive 0%, 6%, 12%, or 25% of their calories as partial enteral nutrition (PEN) in an isocaloric, isonitrogenous fashion. Twenty-four hours before harvest animals were gavaged with lactulose and urinary excretion quantified. At harvest, mesenteric lymph nodes were cultured to assess BT and intestinal histology determined. RESULTS: Provision of as little as 25% of total calories PEN improved nitrogen balance and reduced BT, in a dose dependent fashion. It did not alter TPN-associated increased macromolecular lactulose permeability (4.4% +/- 1.0%). CONCLUSION: Concurrent small amounts of PEN, aimed to support the gut's metabolic needs, are beneficial during periods of prolonged TPN.

Diagnosis and management of the "difficult" abdominal aortic aneurysm: pararenal aneurysms, inflammatory aneurysms, and horseshoe kidney.

All "difficult" abdominal aortic aneurysms-whether pararenal or inflammatory or associated with abnormal renal parenchymal anatomy-often best are approached with some combination of retroperitoneal exposure and supraceliac clamping. Preoperative recognition that an unusual case may exist, complete and appropriate imaging and formulation of a sensible plan before operation are absolutely critical to success. Following such a plan can convert a relatively complex situation into a relatively simple one.

Prosthetic above-knee femoropopliteal bypass.

One of the classic and as yet unresolved arguments in vascular surgery is whether using prosthetic for a first-time above-knee femoropopliteal bypass, to "save the vein" for a later, more distal bypass, is of net benefit. Most of the arguments supporting use of prosthetic for a first bypass in this situation are, in fact, not supported by the literature, whereas most of the arguments in favor of using vein first are. In addition, decision analysis shows that overall amputation-free survival and number of operative procedures required are clearly better if vein is used first under essentially all conditions--the overwhelmingly strongest determinant of outcome is patency of the first bypass, and the superior patency of initial bypass with vein mathematically outweighs the ability of the "preserved" vein to salvage failures after an initial bypass with prosthetic. Theoretical, empirical, and mathematical arguments all strongly favor preferential use of vein for a first bypass to the above-knee popliteal artery.

Reperfusion and compartment syndromes: strategies for prevention and treatment.

Reperfusion syndrome refers to the damage done by restoration of blood flow to ischemic tissues and is distinct from the original ischemic insult itself, whereas compartment syndrome refers to the damage resulting from increased pressure within an enclosed fascial compartment that occurs after blood flow has been restored. Despite extensive experimental work directed toward the treatment of established reperfusion injury and prevention of compartment syndrome, clinical outcome over the past decade has not appreciably changed. Although the systemic insult, thought to be an inevitable result of reperfusion injury, may be less injurious than "conventional wisdom" would suggest, no better strategy for treating compartment syndrome other than early recognition and decompression has yet been developed.

Optimal diagnosis of splenic vein thrombosis: brief clinical report.

The presence of splenic vein thrombosis is sometimes very difficult to diagnose. We present a patient in whom the splenic vein was thought to be patent by ultrasound and conventional celiac angiography. Because of high clinical suspicion and continued bleeding, he underwent a selective intra-arterial digital splenic angiogram. The venous phase clearly showed proximal (hilar) splenic vein occlusion with filling via collaterals in real time. Splenectomy confirmed the diagnosis. We believe that a selective intra-arterial digital splenic angiogram is the radiographic study of choice for suspected splenic vein thrombosis.

Unrecognized carotid artery stenosis discovered by calcifications on a panoramic radiograph.

BACKGROUND: Approximately 730,000 strokes occur each year in the United States, costing an estimated $40 billion annually. One-half of all strokes are the result of atherosclerotic plaques found in the carotid artery. Such plaques frequently are heavily calcified and can be identified on a panoramic radiograph by the incidental finding of calcifications overlying the carotid bifurcation. CASE DESCRIPTION: The authors found that a 67-year-old asymptomatic woman had calcium deposits overlying both carotid bifurcation regions on a panoramic radiograph. Subsequent duplex ultrasonic examination indicated bilateral, high-grade carotid arterial stenoses. The patient underwent uneventful bilateral carotid endarterectomy. CLINICAL IMPLICATIONS: The patient had critical carotid arterial stenoses associated with significant risk of stroke that had not been identified otherwise. The findings on the panoramic radiograph led to appropriate and potentially life-saving treatment. While the positive predictive value of this finding has yet to be defined, the authors believe that calcifications overlying the carotid system region seen on panoramic radiography in an asymptomatic patient should be followed by formal evaluation of the carotid bifurcation.

A condemnation of subcutaneous fasciotomy.

Controversy exists regarding the indications and methods for lower-extremity fasciotomy. Two recent cases at our institution in which recurrent, acute limb-threatening ischemia occurred despite adequate fascial division have convinced us that in certain situations subcutaneous fasciotomy is clearly inadequate. In both patients, both of whom were young, intact healthy skin between the lower extent of the incision and the malleolus acted as a tourniquet, causing recurrent compartment syndrome as reperfusion edema occurred after initial repair. We believe that therapeutic fasciotomy in young patients with relatively noncompliant skin should include division of skin from the knee to the ankle on at least one side to prevent a tourniquet effect by intact skin at the ankle.

Cancer cachexia is transmissible in plasma.

The cause of cancer cachexia is unclear. Tumors may be competing with the host for ingested nutrients or may be releasing some factor that actively inhibits energy utilization. To explore these questions, plasma was sterilely collected and pooled from 103 terminally cachectic Fischer 344 rats implanted with an experimental sarcoma. Control plasma was collected in similar fashion from 138 nontumor-bearing rats (NTBP). Plasma from tumor-bearing rats (TBP) or NTBP was continuously infused in a randomized, blinded fashion for 4 days into 20 normal rats. During infusion, food intake and nitrogen excretion were measured daily. At sacrifice, body weight and organ masses were determined. Rats receiving TBP demonstrated an immediate and profound anorexia compared with those receiving NTBP. Total food intake during treatment was 31.2 +/- 3.3 (g +/- SEM) in the TBP group versus 48.2 +/- 2.8 in the NTBP group (P less than 0.001 by t test). Likewise, the total decline in body weight was greater in the TBP group as compared with the NTBP group (-35.2 +/- 3.4 versus -14.6 +/- 4.0, P less than 0.001). Mean daily nitrogen balance during treatment was negative in the rats receiving TBP (-14.5 +/- 20.1 mg +/- SEM) while remaining highly positive in the rats receiving NTBP (110.7 +/- 19.3, P less than 0.002). Finally, cardiac and gastrocnemius muscle masses were decreased, while hepatic mass was unaffected. These data demonstrate that the syndrome of cancer-associated cachexia is transmissible in plasma and therefore may be mediated by a circulating molecule or molecules. Identification and purification of the molecule(s) responsible for this effect would have obvious clinical benefits.

Measurement of carotid bifurcation pressure gradients using the Bernoulli principle.

Current randomized prospective studies suggest that the degree of carotid stenosis is a critical element in deciding whether surgical or medical treatment is appropriate. Of potential interest is the actual pressure drop caused by the blockage, but no direct non-invasive means of quantifying the hemodynamic consequences of carotid artery stenoses currently exists. The present prospective study examined whether preoperative pulsed-Doppler duplex ultrasonographic velocity (v) measurements could be used to predict pressure gradients (delta P) caused by carotid artery stenoses, and whether such measurements could be used to predict angiographic percent diameter reduction. Preoperative Doppler velocity and intraoperative direct pressure measurements were obtained, and per cent diameter angiographic stenosis measured in 76 consecutive patients who underwent 77 elective carotid endarterectomies. Using the Bernoulli principle (delta P = 4v(2), pressure gradients across the stenoses were calculated. The predicted delta P, as well as absolute velocities and internal carotid artery/common carotid velocity ratios were compared with the actual delta P measured intraoperatively and with preoperative angiography and oculopneumoplethysmography (OPG) results. An end-diastolic velocity of > or = 1 m/s and an end-diastolic internal carotid artery/common carotid artery velocity ratio of > or = 10 predicted a 50% diameter angiographic stenosis with 100% specificity. Although statistical significance was reached, preoperative pressure gradients derived from the Bernoulli equation could not predict actual individual intraoperative pressure gradients with enough accuracy to allow decision making on an individual basis. Velocity measurements were as specific and more sensitive than OPG results. Delta P as predicted by the Bernoulli equation is not sufficiently accurate at the carotid bifurcation to be useful for clinical decision making on an individual basis. However, end-diastolic velocities alone as well as internal carotid artery/ common carotid artery velocity ratios are highly specific in the prediction of clinically significant carotid stenoses. An end-diastolic velocity of > or = 1 m/s accurately identifies a 50% or greater diameter stenosis, and thus may in some cases be sufficient for operation.

Fetal internal iliac artery: case report and embryologic review.

A 25-year-old woman with anomalous circulation to the right leg was seen with a symptomatic aneurysm of the abnormal vessel. The artery, which did share some features of the classic persistent sciatic artery, also had important differences that were not previously described in the literature. The patient manifested several associated vascular and nonvascular congenital anomalies. She underwent resection of the aneurysm and primary operative repair of the artery without difficulty. An embryologic interpretation is offered, and the clinical implications and management strategy are discussed.

Intracerebral hemorrhage after carotid endarterectomy: incidence, contribution to neurologic morbidity, and predictive factors.

PURPOSE: With a diminishing rate of cardiac and neurologic events after carotid endarterectomy, intracerebral hemorrhage is gaining increasing importance as a cause of perioperative morbidity and mortality. To date, information has been largely anecdotal, and there has been no comparison with a control group of patients. METHODS: The records of all patients experiencing symptomatic intracerebral hemorrhage after carotid endarterectomy were reviewed and compared with data from 50 randomly selected patients who did not experience intracranial bleeding. Univariate analyses were performed, using the Fisher exact test for dichotomous data and the Student t test for continuous data. RESULTS: During a 6-year period, symptomatic intracranial hemorrhage developed in 11 (0.75%) of 1471 patients undergoing carotid endarterectomy, accounting for 35% of the 31 total perioperative neurologic events. Hemorrhage occurred a median of 3 days postoperatively (range, 0 to 18 days). Signs and symptoms included hypertension in all 11 patients, headache in 7 conscious patients (64%), and bradycardia in 6 patients (55%). Massive hemorrhage with herniation and death occurred in 4 patients (36%). Moderate hemorrhage developed in 5 patients (45%); 3 of these patients had partial recovery, and 2 had complete recovery. Petechial hemorrhage occurred in the remaining 2 patients (18%), 1 with partial and 1 with complete recovery. In comparison with the control group, there were no differences in respect to sex, indication for operation, smoking or diabetic history, and antiplatelet therapy or perioperative heparin management. Patients with intracranial hemorrhage were, however, younger, more frequently hypertensive, had a higher degree of ipsilateral and contralateral carotid stenosis, and had a higher rate of contralateral carotid occlusion. CONCLUSION: Intracranial hemorrhage occurs with notable frequency after carotid endarterectomy and accounts for a significant proportion of neurologic morbidity and mortality. Younger patients, hypertensive patients, and patients with severe cerebrovascular occlusive disease appear to be at greatest risk for the complication.

Clinical review: irradiation for lower extremity arterial occlusive disease.

Lower extremity atherosclerosis, a disease of aging, is both widespread and increasing in prevalence-it is estimated that almost 100,000 patients per year in the United States require operative bypass for lower extremity ischemia. It is an axiom of vascular surgery that essentially every bypass graft will eventually fail. Many if not most such failures are due to the process of intimal hyperplasia at one or both anastomoses. The search for a "cure" for intimal hyperplasia has been long, but thus far unrewarding. Recent advances in therapeutic irradiation, however, offer a potential solution to this problem. This review is designed to acquaint the radiation oncologist with the basic concepts behind lower extremity atherosclerosis and its treatment, and to introduce briefly the special problems inherent in considering irradiation of an end-to-side anastomosis.

Safety and efficacy of limited-dose tissue plasminogen activator in acute vascular occlusion.

OBJECTIVE: The purposes of this study were to evaluate the safety and efficacy of limited-dose tissue plasminogen activator (t-PA) in patients with acute vascular occlusion and to compare these results with those obtained in equivalent patients receiving urokinase. METHODS: We compared the results of 60 patients receiving catheter-directed urokinase from November 1997 to November 1998 (240,000 units/h x 4 h, 120,000 units/h thereafter for a maximum of 48 h) with those of 45 patients receiving catheter-directed t-PA from November 1998 to August 2000 (2 mg/h, total dose < or =100 mg) for acute arterial occlusion (AAO) and acute venous occlusion (AVO). Interventional approaches such as cross-catheter and coaxial techniques were used to reduce the dose of lytic agent needed to achieve pre-lysis-treatment goals (eg, complete lysis of all thrombus/unmasking graft stenosis or establishing outflow target). Statistical analysis was performed using Student t test and Fisher exact test. RESULTS: The urokinase and t-PA groups were comparable with regard to age, comorbidities (coronary artery disease, hypertension, diabetes, renal insufficiency, smoking), duration of ischemic or occlusive symptoms, location of occlusive process, pretreatment with warfarin, and thrombotic versus embolic and native versus graft occlusion in patients with AAO. In patients with AAO and in those with AVO, t-PA was equivalent to or better than urokinase with regard to percent of clot lysis, incidence of major bleeding complications, limb salvage, and mortality. Achievement of pretreatment goals (arterial patients only) was 50% for urokinase patients and 76% for t-PA patients (P =.02). Analysis of success in individual pretreatment-goal achievement showed urokinase and t-PA to be equivalent in unmasking stenoses (85% and 84%, respectively; P = NS), whereas t-PA was superior to urokinase in the more critical task of establishing run-off (39% versus 81% for urokinase and t-PA, respectively; P =.001). Additional interventions, either endovascular or surgical, were required in 60% and 51% (P = NS) of patients receiving urokinase and t-PA, respectively, for AAO, and in 54% and 62% (P = NS) of patients receiving urokinase and t-PA, respectively, for AVO. CONCLUSIONS: Limited-dose t-PA is a safe and effective therapy for AAO and AVO when administered by experienced teams using innovative but well-established interventional techniques.

Impact of inflow reconstruction on infrainguinal bypass.

PURPOSE: This study assessed whether multisegmental disease that is severe enough to require an inflow procedure adversely affects infrainguinal bypass patency, limb salvage, or patient survival rates. METHODS: The records of 495 patients who underwent 551 infrainguinal bypass grafting procedures were reviewed. Saphenous vein and prosthetic grafts were evaluated separately. Graft patency rates, patient limb salvage rates, and patient survival rates in those grafts that arose from a reconstructed inflow source were compared with those that arose from normal, nonreconstructed inflow sources. When grafts had either hemodynamic failure or occlusion, the cause of failure was identified. RESULTS: Four-year primary patency rates in vein grafts that arose from a reconstructed inflow sources were lower than those in grafts that arose from nonreconstructed inflow sources (41% vs 54%; p = 0.006). Assisted primary patency rates and secondary patency rates, however, were similar (62% vs 74% and 64% vs 77%, respectively). The 4-year primary patency rate (45% vs 55%), assisted primary patency rate (60% vs 60%), and secondary patency rate (60% vs 61%) in prosthetic grafts did not vary based on inflow source. The most common cause of graft failure was inflow failure, except in the vein grafts that did not require an inflow procedure, in which the most common cause of failure was graft failure. Inflow failure occurred in 24% and 22% of the vein and prosthetic grafts with multisegmental disease, respectively, but in only 7% (p < 0.001) and 10% (p < 0.05), respectively, of those that arose from normal nonreconstructed inflow. The presence of an inflow procedure did not affect limb salvage rates or patient survival rates, regardless of graft material. CONCLUSIONS: Long-term patency rates, patient limb salvage rates, and survival rates in patients with a reconstructed inflow source were similar to those of patients with a normal nonreconstructed inflow. A major cause of occlusion is inflow failure, and this occurs in a greater proportion of patients with multisegmental disease. These patients, in particular, may benefit from patient surveillance to screen for progression of their inflow disease and to allow for intervention before infrainguinal graft occlusion.