Percutaneous aspiration of fluid for management of peritonitis in space.

BACKGROUND: As a medical emergency that can affect even well-screened, healthy individuals, peritonitis developing during a long-duration space exploration mission may dictate deviation from traditional clinical practice due to the absence of otherwise indicated surgical capabilities. Medical management can treat many intra-abdominal processes, but treatment failures are inevitable. In these circumstances, percutaneous aspiration under sonographic guidance could provide a "rescue" strategy. HYPOTHESIS: Sonographically guided percutaneous aspiration of intra-peritoneal fluid can be performed in microgravity. METHODS: Investigations were conducted in the microgravity environment of NASA's KC-135 research aircraft (0 G). The subjects were anesthetized female Yorkshire pigs weighing 50 kg. The procedures were rehearsed in a terrestrial animal lab (1 G). Colored saline (500 mL) was introduced through an intra-peritoneal catheter during flight. A high-definition ultrasound system (HDI-5000, ATL, Bothell, WA) was used to guide a 16-gauge needle into the peritoneal cavity to aspirate fluid. RESULTS: Intra-peritoneal fluid collections were easily identified, distinct from surrounding viscera, and on occasion became more obvious during weightless conditions. Subjectively, with adequate restraint of the subject and operators, the procedure was no more demanding than during the 1-G rehearsals. CONCLUSIONS: Sonographically guided percutaneous aspiration of intra-peritoneal fluid collections is feasible in weightlessness. Treatment of intra-abdominal inflammatory conditions in spaceflight might rely on pharmacological options, backed by sonographically guided percutaneous aspiration for the "rescue" of treatment failures. While this risk mitigation strategy cannot guarantee success, it may be the most practical option given severe resource limitations.

Surgical instrument restraint in weightlessness.

BACKGROUND: Performing a surgical procedure during spaceflight will become more likely in the future as the duration of missions becomes longer. Only minimal surgical capability was available on previous missions since the definitive medical care time was short and the likelihood of a surgical event too low to justify carrying surgical hardware onboard. Early demonstrations of surgical procedures in the microgravity environment of parabolic flight indicated the need for careful logistical planning and restraint of surgical hardware. Human ergonomics also has more effect in microgravity than in the conventional 1-G environment. METHODS: Three methods of surgical instrument restraint--a Minor Surgical Kit (MSK), a Surgical Restraint Scrub Suit (SRSS), and a Surgical Tray (ST)--were evaluated in parabolic flight surgical procedures. RESULTS: The MSK was easily stored, easily deployed, and demonstrated the best ability to facilitate a surgical procedure in microgravity. CONCLUSION: Important factors in a surgical restraint system for microgravity include excellent organization of supplies, ability to maintain sterility, accessibility while providing secure restraint, ability to dispose of sharp items and biological trash, and ergonomic efficiency.

Comparative effects of cilostazol and other therapies for intermittent claudication.

Many patients with peripheral arterial disease (PAD) have intermittent claudication or problems with ambulation and mobility. Exercise and smoking cessation are primary therapies for claudication, but drug treatment may provide additional benefit. The data supporting use of pentoxifylline for claudication are weak, and pentoxifylline is not generally accepted as efficacious. Cilostazol is a new drug for the treatment of claudication. It appears to modestly benefit walking ability and it has other potentially useful effects, including inhibition of platelet aggregation and beneficial effects on serum lipids. In a randomized, prospective, double-blind trial examining walking ability in patients with PAD with moderate-to-severe claudication, cilostazol was superior to both placebo and pentoxifylline.

Modeling and simulation for space medicine operations: preliminary requirements considered.

The NASA Space Medicine program is now developing plans for more extensive use of high-fidelity medical simulation systems. The use of simulation is seen as means to more effectively use the limited time available for astronaut medical training. Training systems should be adaptable for use in a variety of training environments, including classrooms or laboratories, space vehicle mockups, analog environments, and in microgravity. Modeling and simulation can also provide the space medicine development program a mechanism for evaluation of other medical technologies under operationally realistic conditions. Systems and procedures need preflight verification with ground-based testing. Traditionally, component testing has been accomplished, but practical means for "human in the loop" verification of patient care systems have been lacking. Medical modeling and simulation technology offer potential means to accomplish such validation work. Initial considerations in the development of functional requirements and design standards for simulation systems for space medicine are discussed.

A comparison of cilostazol and pentoxifylline for treating intermittent claudication.

PURPOSE: We performed a randomized, double-blind, placebo-controlled, multicenter trial to evaluate the relative efficacy and safety of cilostazol and pentoxifylline. PATIENTS AND METHODS: We enrolled patients with moderate-to-severe claudication from 54 outpatient vascular clinics, including sites at Air Force, Veterans Affairs, tertiary care, and university medical centers in the United States. Of 922 consenting patients, 698 met the inclusion criteria and were randomly assigned to blinded treatment with either cilostazol (100 mg orally twice a day), pentoxifylline (400 mg orally 3 times a day), or placebo. We measured maximal walking distance with constant-speed, variable-grade treadmill testing at baseline and at 4, 8, 12, 16, 20, and 24 weeks. RESULTS: Mean maximal walking distance of cilostazol-treated patients (n = 227) was significantly greater at every postbaseline visit compared with patients who received pentoxifylline (n = 232) or placebo (n = 239). After 24 weeks of treatment, mean maximal walking distance increased by a mean of 107 m (a mean percent increase of 54% from baseline) in the cilostazol group, significantly more than the 64-m improvement (a 30% mean percent increase) with pentoxifylline (P <0.001). The improvement with pentoxifylline was similar (P = 0.82) to that in the placebo group (65 m, a 34% mean percent increase). Deaths and serious adverse event rates were similar in each group. Side effects (including headache, palpitations, and diarrhea) were more common in the cilostazol-treated patients, but withdrawal rates were similar in the cilostazol (16%) and pentoxifylline (19%) groups. CONCLUSION: Cilostazol was significantly better than pentoxifylline or placebo for increasing walking distances in patients with intermittent claudication, but was associated with a greater frequency of minor side effects. Pentoxifylline and placebo had similar effects.

A new pharmacological treatment for intermittent claudication: results of a randomized, multicenter trial.

BACKGROUND: Effective medication is limited for the relief of intermittent claudication, a common manifestation of arterial occlusive disease. Cilostazol is a potent inhibitor of platelet aggregation with vasodilation effects. OBJECTIVE: To evaluate the safety and efficacy of cilostazol for the treatment of intermittent claudication. METHODS: Thirty-seven outpatient vascular medicine clinics at regional tertiary and university hospitals in the United States participated in this multicenter, randomized, double-blind, placebo-controlled, parallel trial. Of the 663 screened volunteer patients with leg discomfort, a total of 516 men and women 40 years or older with a diagnosis of moderately severe chronic, stable, symptomatic intermittent claudication were randomized to receive cilostazol, 100 mg, cilostazol, 50 mg, or placebo twice a day orally for 24 weeks. Outcome measures included pain-free and maximal walking distances via treadmill testing, patient-based quality-of-life measures, global assessments by patient and physician, and cardiovascular morbidity and all-cause mortality survival analysis. RESULTS: The clinical and statistical superiority of active treatment over placebo was evident as early as week 4, with continued improvement at all subsequent time points. After 24 weeks, patients who received cilostazol, 100 mg, twice a day had a 51% geometric mean improvement in maximal walking distance (P<.001 vs placebo); those who received cilostazol, 50 mg, twice a day had a 38% geometric mean improvement in maximal walking distance (P<.001 vs placebo). These percentages translate into an arithmetic mean increase in distance walked, from 129.7 m at baseline to 258.8 m at week 24 for the cilostazol, 100 mg, group, and from 131.5 to 198.8 m for the cilostazol, 50 mg, group. Geometric mean change for pain-free walking distance increased by 59% (P<.001) and 48% (P<.001), respectively, in the cilostazol, 100 mg, and cilostazol, 50 mg, groups. These results were corroborated by the results of subjective quality-of-life assessments, functional status, and global evaluations. Headache, abnormal stool samples or diarrhea, dizziness, and palpitations were the most commonly reported potentially drug-related adverse events and were self-limited. A total of 75 patients (14.5%) withdrew because of any adverse event, which was equally distributed between all 3 treatment groups. Similarly, there were no differences between groups in the incidence of combined cardiovascular morbidity or all-cause mortality. CONCLUSION: Compared with placebo, long-term use of cilostazol, 100 mg or 50 mg, twice a day significantly improves walking distances in patients with intermittent claudication.

The effect of withdrawal of drugs treating intermittent claudication.

BACKGROUND: Pharmacologic treatment for intermittent claudication is a management option. This study evaluated the effect of withdrawal of drug therapies, cilostazol and pentoxifylline, on the walking ability of peripheral artery disease patients. METHODS: Single-blind placebo crossover from a randomized, double-blind trial; 45 claudication patients received either cilostazol 100 mg orally twice daily (n = 16), pentoxifylline 400 mg orally three times daily (n = 13), or placebo (n = 16) for 24 weeks. After 24 weeks of double-blind therapy, treatment for all groups was placebo only, and follow-up continued through week 30. Treatment efficacy was established with treadmill testing. RESULTS: Profile analysis demonstrated a highly significant loss of treatment benefit after crossover (P = 0.001) for cilostazol-treated patients, but no significant change after crossover was observed with pentoxifylline. CONCLUSIONS: Drug withdrawal worsened the walking of claudicants who had benefited from cilostazol therapy. This decline with crossover to placebo suggests that the initial improvement with cilostazol treatment was due to the drug's action. Withdrawal of pentoxifylline did not adversely affect walking.

Temporary arterial shunts to maintain limb perfusion after arterial injury: an animal study.

BACKGROUND: Temporary shunt placement can quickly restore perfusion after extremity arterial injury. This study examined the adequacy of limb blood flow with shunt use, non-heparin-bonded shunt patency over prolonged periods, and the safety of this technique. METHODS: Common iliac arteries were divided and 4.0-mm Silastic Sundt shunts placed in 16 anesthetized pigs. Eight (group I) had shunts placed immediately; eight others (group II) were shunted after an hour of limb ischemia and hemorrhagic shock. Physiologic parameters and femoral artery blood flow in both hindlimbs were continuously monitored. Limb lactic acid generation, oxygen utilization, and hematologic and metabolic effects were serially evaluated for 24 hours. RESULTS: Shunts remained patent in 13 of 16 pigs. Shunts thrombosed in two group I animals because of technical errors, but functioned well after thrombectomy and repositioning. Patency could not be maintained in one animal that died from shock. Flow in group I shunted limbs was 57 (+/-11 SD) % of control. For group II animals in shock, shunted limb flow initially averaged 46 +/- 15% of control, but 4 hours after shunt placement, the mean limb blood flow was the same as in group I. Increased oxygen extraction compensated for the lower flow. Lactic acid production was not increased in comparison to control limbs. CONCLUSION: Shunts provided adequate flow in this model of extremity trauma. Correctly placed shunts stayed patent for 24 hours, without anticoagulation, if shunt placement followed resuscitation.

The correlation of early flow disturbances with the development of infrainguinal graft stenosis: a 10-year study of 341 autogenous vein grafts.

PURPOSE: Although duplex surveillance of infrainguinal bypass grafts is widely accepted, the optimal frequency and intensity of graft surveillance remains controversial. Earlier reports have suggested that grafts can be stratified into high-risk and low-risk groups based on the presence or absence of early graft flow disturbances. The purpose of this study was to provide long-term data in determining whether early graft flow disturbances detected by means of duplex scanning can predict the development of intrinsic vein graft stenosis. METHODS: We reviewed a series of patients undergoing prospective duplex graft surveillance after autogenous infrainguinal bypass grafting procedures from 1987 to 1997. Patients included in the study underwent at least one duplex scan within 3 months of graft implantation and were observed for a minimum of 6 months. Grafts were categorized as abnormal when a focal flow disturbance with a peak systolic velocity greater than 150 cm/s was identified within 3 months of graft implantation. RESULTS: Of 341 vein grafts in 296 patients who met inclusion criteria, 89 grafts (26%) required revision for intrinsic stenosis; the mean follow-up period was 35 months (range, 6 months to 10 years). Early flow disturbances were detected in 84 (25%) grafts. Grafts with early flow disturbances were more likely to ultimately require revision (43% vs 21%; P =. 0001) and required initial revision earlier (8 months vs 16 months; P =.019). Eighty-two percent of initial graft revisions occurred in the first 2 postoperative years; 69% occurred in the first year. However, an annual 2% to 4% incidence of late-appearing graft stenosis persisted during long-term follow-up. An additional 24 patients (7% of grafts) required an inflow or outflow reconstruction. CONCLUSION: Grafts with early postoperative flow disturbances detected by means of duplex scanning have nearly three times the incidence of graft-threatening stenosis and an earlier requirement for revision, when compared with normal grafts. This suggests that the biology and etiology of these lesions may differ. These data support not only aggressive efforts to detect early graft lesions to stratify grafts at highest risk, but also continued lifelong graft surveillance to detect late-appearing lesions, inflow and outflow disease progression, and maximize graft patency.

Cilostazol has beneficial effects in treatment of intermittent claudication: results from a multicenter, randomized, prospective, double-blind trial.

BACKGROUND: Cilostazol is a new phosphodiesterase inhibitor that suppresses platelet aggregation and also acts as a direct arterial vasodilator. This prospective, randomized, placebo-controlled, parallel-group clinical trial evaluated the efficacy of cilostazol for treatment of stable, moderately severe intermittent claudication. METHODS AND RESULTS: Study inclusion criteria included age > or =40 years, initial claudication distance (ICD) on treadmill (12.5% incline, 3.2 km/h) between 30 and 200 m, and confirmation of diagnosis of chronic lower-extremity arterial occlusive disease. After stabilization and single-blind placebo lead-in, 81 subjects (62 male, 19 female) from 3 centers were randomized unequally (2:1) to 12 weeks of treatment with cilostazol 100 mg PO BID or placebo. Primary outcome measures included ICD and maximum distance walked (absolute claudication distance, or ACD). Secondary outcome measures included ankle pressures, subjective assessments of benefit by patients and physicians, and safety. Treatment and control groups were similar with respect to age, severity of symptoms, ankle pressures, and smoking status. Statistical analyses used intention-to-treat analyses for each of 77 subjects who had > or =1 treadmill test after initiation of therapy. Comparisons between groups were based on logarithms of ratios of ICD and ACD changes from baseline using ANOVA test at last treatment visit. The estimated treatment effect showed a 35% increase in ICD (P<0.01) and a 41% increase in ACD (P<0.01). There was no significant change in resting or postexercise ankle/brachial indexes. Patients' and physicians' subjective assessments corroborated the measured improvements in walking performance observed in the cilostazol-treated group. CONCLUSIONS: Cilostazol improved walking distances, significantly increasing ICD and ACD. The data suggest cilostazol is safe and well tolerated for the treatment of intermittent claudication.

The role of infrapopliteal MR angiography in patients undergoing optimal contrast angiography for chronic limb-threatening ischemia.

PURPOSE: To determine the benefit of infrapopliteal magnetic resonance angiography (MRA) in patients with chronic limb-threatening ischemia who have undergone optimal contrast angiography (CA). PATIENTS AND METHODS: Thirty-four patients (37 limbs) with limb-threatening chronic lower extremity ischemia underwent MRA and CA of the symptomatic extremity. Selective, vasodilator-enhanced digital subtraction angiography of the infrapopliteal vessels was possible for 34 limbs. Two vascular surgeons retrospectively formulated treatment plans based on CA. They then formulated treatment plans based on CA and MRA together. RESULTS: CA clearly visualized 495 of 888 vascular segments as patent, while MRA clearly visualized 412 of 888 segments. Treatment plans differed for at least one of two surgeons in eight limbs, but MRA would possibly have improved clinical outcome in only one. The amount of inflow disease did not appear to influence segment visualization or treatment planning. In eight of 11 limbs that eventually required below- or above-knee amputation, CA clearly visualized more vascular segments than MRA. One patient developed renal insufficiency after CA. CONCLUSION: Most patients undergoing optimal CA for chronic limb-threatening ischemia will not benefit from the addition of MRA. However, MRA should be considered when CA is suboptimal and when it is necessary to conserve contrast material.

Preoperative testing before carotid endarterectomy: a survey of vascular surgeons' attitudes.

Traditional surgical practice and published consensus statements from major vascular surgery specialty societies have considered contrast arteriography to be a routine part of the diagnostic evaluation prior to carotid endarterectomy (CEA). However, some surgeons now omit routine preoperative arteriography if a technically adequate carotid duplex scan is performed and indications for CEA are clear. To better establish current practice patterns and to characterize vascular surgeons' opinions about the role of preoperative arteriography, the Peripheral Vascular Surgery Society membership was surveyed by mail. Eighty-six percent of the members responded (430 of 502). Ninety-three percent of all patients considered for CEA are evaluated with duplex scanning; 82% with arteriography. While the majority of surgeons typically obtain both a duplex scan and an arteriogram, 70% have performed CEA without a preoperative arteriogram. Brain imaging studies (CT or MRI) are obtained in 26% and MR angiograms in 10% of cases. Seventy-five percent of the surgeons agreed with the statement that CEA without preoperative arteriography is an acceptable practice if appropriate indications for surgery are present. Furthermore, one third believed that CEA without a preoperative arteriogram is generally acceptable (acceptable more than half the time). Respondents were stratified by surgical experience time in practice and practice type. No significant differences in responses were found, suggesting the acceptance of CEA without preoperative arteriography is broad-based. This survey demonstrates changing attitudes among practicing vascular surgeons regarding the necessity for routine arteriography prior to CEA. Carotid endarterectomy on the basis of duplex scanning and clinical assessment should be considered an accepted alternative.

Noninvasive assessment of renal artery stenosis.

Noninvasive diagnostic methods for evaluation of renal arteries continue to improve. Contrast arteriography is the reference standard to which other techniques are compared, and preoperative arteriography before operative or endovascular therapy remains the practice standard. However, noninvasive examination methods have supplanted arteriography as a screening test for renal artery occlusive disease, and they allow more selective use of the invasive technique. ACE inhibitor-enhanced renal scintigraphy has improved on the sensitivity of standard renal scintigraphy, but several investigators found it still lacks when significant renal dysfunction is present. A positive scan implies the renal artery lesion is functionally significant and is predictive of a response to therapy. Although ACE inhibitor-enhanced renal scintigraphy can detect significant renal artery disease, it can neither localize the arterial lesion nor can it characterize the severity of the stenosis. Renal scintigraphy therefore lacks utility as a method to follow progression of the arterial disease. Magnetic resonance and helical CT imaging are advanced technologies that acquire axial imaging data, but with advanced software and powerful image processing hardware, the anatomic information can be represented in multiple planes or with three-dimensional reconstructions. The anatomic information provided is not limited to the renal arteries, but can define relationships to the surrounding anatomy. Validation studies from several institutions suggest that although these methods for renal artery assessment may be sufficiently accurate for screening use, they remain relatively expensive and are just now becoming more widely available. Not all patients can be studied. Helical CT scanning requires a relatively large intravenous contrast dose, which is undesirable in patients with renal insufficiency, and it seems to underestimate severity of some renal artery stenoses. MRA is impractical or unsafe for patients with claustrophobia, cardiac dysrhythmias, pacemakers, certain types of metallic implants or clips, or for seriously ill patients requiring monitoring. Duplex scanning is both sensitive and specific. It is the least expensive of the available diagnostic modalities, and it is completely safe and noninvasive. Not only is the presence of a renal artery lesion detectable, the severity of the stenosis can be categorized and its hemodynamic significance or renal blood flow can be evaluated. Renal artery duplex scanning is the optimal method for renal artery assessment when it is available from a validated vascular laboratory. However, this last point is the key. The utility of the study is entirely dependent on the skill and experience of the examining technologist. Other drawbacks to duplex scanning include the fact that to yield the "whole picture" of the anatomy and pathology requires a mental synthesis. Real-time scanning generates a series of images and flow data that must be interpreted with a understanding of how the scan was performed. Clinical circumstances, local expertise, equipment availability, costs, and other important considerations will factor into the decision-making process of planning a work-up for suspected renal artery stenosis. The noninvasive diagnostic technologies continue to advance, and as new methods are validated, the need for arteriography may be further lessened.

Successful treatment of early postoperative aortic graft infection by percutaneous catheter drainage.

Successful treatment by percutaneous catheter drainage of an acute aortic graft infection with an associated pancreatic fistula is reported. Percutaneous catheter drainage can be considered in selected patients when the risk of reoperation is deemed unacceptable or when other reasonable treatment options do not exist.

Does infrapopliteal arterial runoff predict success for popliteal artery aneurysmorrhaphy?

BACKGROUND: A 6-year experience with surgical management of popliteal artery aneurysms (PAAs) was examined to determine the influence of infrapopliteal outflow vessel patency on the long-term success of popliteal artery aneurysmorrhaphy. METHODS: Arteriograms were reviewed to characterize the anatomy of the infrapopliteal arterial runoff. Regular clinical evaluation and prospective serial duplex scan surveillance assessed graft patency. RESULTS: A total of 28 patients underwent 45 popliteal aneurysmorrhaphies. Elective repair was performed in 32 limbs (71%); emergency treatment was needed for 13 limbs (29%) because of acute limb-threatening ischemia. All patients were managed with PAA exclusion and reversed saphenous vein grafting. Only 20 limbs (44%) had a patent trifurcation with three continuous vessels to the ankle, 13 (29%) had two continuous tibial vessels, 10 (22%) had one patent runoff artery, and 2 (4%) had no vessel continuous to the foot. With a mean follow-up of 19.1 months, the 5-year primary graft patency by life-table analysis was 95 +/- 12.3%, with a 5-year assisted primary patency of 97 +/- 10.0%. One vein graft underwent elective secondary revision. Another graft thrombosed, requiring a secondary bypass. Outcome did not correlate with the status of the runoff anatomy. Limb salvage was 100%. CONCLUSION: The use of autologous reversed vein grafting and attention to technical details yielded normal graft hemodynamics and excellent long-term patency and limb salvage despite the suboptimal runoff anatomy associated with PAAs.

Ultrasound determination of total arterial wall thickness.

PURPOSE: Ultrasonic measurement techniques for determining intima-media thickness and total arterial wall thickness have been described. The intima-media thickness measurements are currently in use in large epidemiologic trials. Intima-media thickness does not evaluate extramedial atherosclerotic change and so may not fully reflect pathologic changes in the arterial wall. METHODS: After we performed variability studies of B-mode image acquisition and measurement, we measured total wall thickness and intima-media thickness of the common carotid arteries in 60 adult subjects in three groups: a control group aged 20 to 29 years, a control group aged 60 to 79 years, and a claudication group aged 60 to 79 years. Measurements were made with B-mode ultrasound images. RESULTS: No statistical difference between sexes was noted. A statistically significant (p < or = 0.05) increase in intima-media thickness and wall thickness was found with increasing age, and an additional increase was observed with clinically significant lower extremity arterial occlusive disease (p < or = 0.05). Image quality had an effect on measurement accuracy. CONCLUSIONS: The finding that the wall thickness of common carotid arteries is increased in those patients with clinically significant lower extremity disease supports the theory that atherosclerosis affects the arterial wall in a systemic fashion. Because intima-media thickness also increases across subject groups without change in its proportional contribution to the total arterial wall thickness, extramedial arterial changes also occur with aging and the development of atherosclerosis. We propose that because increases in wall thickness measurements of common carotid arteries follow intima-media thickness increase (but do not necessarily measure the same physiologic change) and the wall thickness method can be used in cases when the intima-media thickness cannot be measured, arterial wall thickness measurement may serve as an alternate or confirmatory test of peripheral artery atherosclerotic severity.

Vascular grafts in head and neck reconstructive surgery.

The best management of advanced head and neck tumors invading the carotid artery utilizes a collaborative, anticipatory approach. Preoperative characterization of the anatomy and extent of tumor involvement, coupled with the physiologic assessment of the cerebrovascular circulation through the variety of adjunctive studies, facilitates operative planning. Careful preoperative evaluation allows the surgeon to make the most informed decision regarding extracranial carotid artery reconstruction, should carotid artery resection be required for adequate tumor removal. When the preoperative evaluation indicates that adequate cerebral perfusion or collateral reserve will not be maintained with carotid artery occlusion, carotid artery reconstruction needs to accompany any resection of this vessel. Autogenous saphenous vein remains the graft conduit of choice, but prosthetic materials may be used. Graft patency and healing require appropriate concomitant soft-tissue coverage of any overlying mucosal or cutaneous defects.

The role of duplex scanning and arteriography before carotid endarterectomy: a prospective study.

PURPOSE: This study examines the current role of diagnostic tests done before carotid endarterectomy and the need for routine arteriography. METHODS: We prospectively studied vascular surgeons' decision-making over a 29-month period during which 111 carotid arteries in 103 patients were considered for endarterectomy. For each case the surgeon's management plan was recorded after clinical evaluation and review of the duplex scan findings, but before arteriography. This plan was later compared with the patient's ultimate clinical management. RESULTS: Of 111 total cases in this period, 17 were excluded from analysis because arteriography was not done or it was performed before the surgeon's evaluation. Carotid duplex scans were diagnostic in 87 (93%) of the remaining 94 cases. The carotid lesion was incompletely assessed by duplex scanning in seven patients because the disease was not limited to the distal common or proximal internal carotid artery (n = 4); anatomic or pathologic features of the carotid artery interfered with imaging or accurate Doppler assessment (n = 1); or an internal carotid artery occlusion could not be distinguished from a high-grade stenosis (n = 2). When a technically adequate duplex scan showed significant disease of the carotid bifurcation, arteriography contributed information that affected clinical management in only a single case (1%). This patient had a middle cerebral artery occlusion distal to a high-grade carotid bifurcation stenosis. CONCLUSIONS: Clinical assessment and duplex scanning were sufficient for the preoperative evaluation of 93% of the candidates for carotid endarterectomy. Clinical circumstances or atypical duplex scan findings can be used to identify the minority of patients for whom arteriography is necessary. On the basis of this experience, we have developed practical guidelines for the selective use of arteriography before carotid endarterectomy.

Neovascularization of canine sutured and stapled small intestinal anastomoses.

New blood vessels develop as a gastrointestinal anastomosis heals. The morphologic aspects of this neovascularization were studied in 22 dogs, each of which underwent one sutured and one stapled small bowel anastomosis. At intervals ranging from three to 24 days after surgery, the dogs were killed, and the bowel was injected with Batson's compound or india ink. The pattern of vascular growth across the anastomotic site was studied. Both stapled and sutured anastomoses caused an increase in submucosal capillary density at day three compared with control specimens taken from bowel remote from the anastomotic site. This increase was maintained consistently through day 24 in sutured anastomoses but had decreased by day five in stapled anastomoses. Growth of submucosal vessel across the anastomotic site could be demonstrated by day three in sutured and day four in stapled anastomoses. The more vigorous inflammatory response associated with sutured anastomoses may be responsible for more rapid and prominent neovascularization.