Mechanisms of resistance to three mite growth inhibitors of Tetranychus urticae in hops

Mite growth inhibitors (MGIs), such as etoxazole and hexythiazox, are valuable IPM tools for Tetranychus urticae control in hops due to their unique mode of action and selectivity. Hence, it is necessary to standardize bioassay methods to evaluate the efficacy of MGIs, monitor resistance, and identify mechanisms underlying MGI resistance in the field. Here, we developed a three-tiered approach for evaluating ovicidal toxicity of MGIs to T. urticae, which simulated different MGI exposure scenarios in the field. The most effective bioassay method was direct exposure of T. urticae eggs to MGIs. With this method, four field-collected T. urticae populations showed low-to-moderate resistance to MGIs. Cross-resistance among MGIs and from MGIs to bifenazate and bifenthrin was detected. Besides target site insensitivity, enhanced cytochrome P450 and esterase activities also contribute to the MGI resistance in hop yard-collected T. urticae populations. Low-to-moderate MGI resistance in T. urticae populations may be mediated by multiple mechanisms. Positive selection pressure on the I1017F mutation is moderate in field-collected T. urticae populations. Further studies are required to identify metabolic detoxification genes that confer resistance to MGIs for precise resistance monitoring.

Quadrat method for assessing the population abundance of a commercially managed native soil-nesting bee, Nomia melanderi (Hymenoptera: Halictidae), in proximity to alfalfa seed production in the western United States

Alkali bees, Nomia melanderi Cockerell, are solitary, gregarious, soil-nesting bees native to the western United States that are commercially managed in the Walla Walla Valley of Washington State to provide pollination service on alfalfa, Medicago sativa L., produced as a seed crop. In 2010 and 2011, we compared two techniques for estimating N. melanderi abundance in commercially managed bee beds. The first technique involved quantifying the abundance of emergence holes in 24 0.5-m2 quadrats on the surface of 13 bee beds during the peak period of N. melanderi foraging activity in July of both years. When we counted emergence holes, we marked a subset of eight quadrats per bee bed with plastic tabs. Subsequently, in late October of the same year, 0.014-m3 soil cores were collected in close proximity to the plastic tabs. The soil cores were teased apart in the laboratory and the absolute abundance of overwintering prepupae was quantified per core. Simple regression was highly significant between the means of emergence holes within the 0.5-m2 soil surface quadrats and the means of the counts from the 0.014-m3 soil cores. Using mean emergence hole counts, mean prepupae counts from the soil cores, and the surface area of the bee beds, we were able to calculate the estimated abundance of N. melanderi in each bee bed. We conclude that the nondestructive quadrat method of sampling N. melanderi abundance in commercially managed beds is robust compared with the destructive, labor-intensive, absolute soil core method.

Intimate partner violence and companion animal welfare

OBJECTIVE

To investigate the effect of intimate partner violence (IPV) on companion animal welfare.

DESIGN

Self-selected telephone survey of people meeting the criteria.

METHODS

Members of the Australian public with experience of IPV and concurrent companion animal ownership were invited to telephone a researcher for a semi-structured interview.

RESULTS

In total, 26 Australian women reported one or more companion animals in the household being verbally and/or physically abused by their male partner, usually with prolonged effects on animal behaviour; 92% indicated that they had been unwilling to discuss the animal abuse with a veterinarian. Many were unaware of animal accommodation services for people fleeing violence and those who did know about these were unwilling to use them, citing their bond with the animals as the main reason. Animals targeted for abuse were most likely to be dogs and owned by women rather than men, children or both partners.

CONCLUSION

Animals can be severely affected by domestic violence situations and many people experiencing violence are unwilling to confide in veterinarians or seek help from animal shelters.

Development of biological control of Tetranychus urticae (Acari: Tetranychidae) and Phorodon humuli (Hemiptera: Aphididae) in Oregon hop yards

The temporal development of biological control of arthropod pests in perennial cropping systems is largely unreported. In this study, the development of biological control of twospotted spider mite, Tetranychus urticae Koch, and hop aphid, Phorodon humuli (Schrank), in a new planting of hop in Oregon is described over a period of 9 yr (2005-2013). Both the abundance and diversity of natural enemies increased over time. Known predators of hop aphid (Coccinellidae and Anthocoridae) were present in all years; however, stable biological control of hop aphid was not achieved in most years and aphicides were required to suppress populations at commercially acceptable levels in 5 of 9 yr. Populations of aphidophagous coccinellids developed synchronously with hop aphid populations, and temporal correlations indicated these are the primary predatory insect associated with hop aphid regulation. However, sampling methods did not assess levels of aphid parasitoids and hyperparasitoids and their contribution to biological control was unquantified. Spider mite biological control was associated primarily with predatory mites (Phytoseiidae) and Stethorus spp. (Coccinellidae). The magnitude of temporal correlations of abundance of these predators with spider mites was found to be greatest on the same sampling dates and at lags of 7-14 d. Stable biological control of spider mites occurred after four field seasons, suppressing spider mites to levels similar to those commonly achieved with chemical control. A survey of 11 commercial hop yards in Oregon documented pest and natural enemy densities under commercial management practices over a period of 4 yr (2008-2011). Natural enemy abundance in commercial hop yards was similar to that of a 2- to 3-yr-old hop yard with limited disturbance. Whereas total reliance on biological control for hop aphid is unlikely to be successful, there appears to be unrealized potential for biological control of spider mites in commercial production. Dynamic action thresholds that consider the value of natural enemies are needed for both pests.

Pseudococcus maritimus (Hemiptera: Pseudococcidae) and Parthenolecanium corni (Hemiptera: Coccidae) are capable of transmitting grapevine leafroll-associated virus 3 between Vitis x labruscana and Vitis vinifera

The grape mealybug, Pseudococcus maritimus (Ehrhorn), and European fruit lecanium scale, Parthenolecanium corni (Bouché), are the predominant species of Coccoidea in Washington State vineyards. The grape mealybug has been established as a vector of Grapevine leafroll-associated virus 3 (GLRaV-3) between wine grape (Vitis vinifera L.) cultivars, elevating its pest status. The objective of this study was to determine if GLRaV-3 could be transmitted between Vitis x labruscana L. and V. vinifera by the grape mealybug and scale insects. Three transmission experiments were conducted with regard to direction; from V. vinifera to V. x labruscana L., from V. x labruscana L. to V. x labruscana L., and from V. x labruscana L. to V. vinifera. Each experiment was replicated 15 times for each vector species. Crawlers (first-instars) of each vector species were allowed 1-wk acquisition and inoculation access periods. The identities of viral and vector species were confirmed by reverse transcription-polymerase chain reaction, cloning, and sequencing of species-specific DNA fragments. GLRaV-3 was successfully transmitted by both species in all experiments, although Ps. maritimus was a more efficient vector under our experimental conditions. To the best of our knowledge, this study represents the first documented evidence of interspecific transmission of GLRaV-3 between two disparate Vitis species. It also highlights the potential role of V. x labruscana L. in the epidemiology of grapevine leafroll disease as a symptomless source of GLRaV-3 inoculum.

Pheromone-based monitoring of Pseudococcus maritimus (Hemiptera: Pseudococcidae) populations in concord grape vineyards

The grape mealybug, Pseudococcus maritimus (Ehrhorn), is the dominant mealybug in Washington's Concord grape vineyards (Vitis labrusca L.). It is a direct pest of fruit clusters and a vector of grapevine leafroll-associated viruses. Using traps baited with the sex pheromone of Ps. maritimus, we determined the optimal trap density for monitoring Ps. maritimus, with the goal of providing a more rapid monitoring method for Ps. maritimus than visual surveys. Varying densities of pheromone-baited traps (one, four, and eight traps per 12.14 ha) were deployed in Concord vineyards to monitor Ps. maritimus seasonal phenology in 2010 and 2011. In both years, flights of adult males were detected in early May and captures peaked twice per season in mid-June and mid-August, indicating two generations each year. Trap data were analyzed using Taylor's Power Law, Iwao's patchiness regression, and the K parameter of the negative binomial model to determine optimal sample size. The formula using the K parameter provided the lowest required sample size, showing that four to eight traps per 12.14 ha were needed to provide 30% sampling precision efficiency throughout the entire season. Fewer traps were needed during flight peaks when trap capture numbers were great. Only one pheromone-baited trap per 12.14 ha was sufficient to provide Ps. maritimus flight phenology data to make informed management decisions. Species-specific pheromone-baited traps deployed for Planococcus ficus (Signoret), Pseudococcus longispinus (Targioni Tozzetti), and Pseudococcus viburni (Signoret) did not detect any of these species in the vineyards sampled.

Results of endovascular superficial femoral endarterectomy

BACKGROUND

Endovascular superficial femoral artery (SFA) endarterectomy with a ring stripper/cutter and distal stenting has been suggested to have a patency comparable with above-knee bypass surgery. We report our initial experience with this technique.

METHODS

Seventeen patients (13 men and 4 women; mean age, 64 years) with SFA occlusion and above-knee popliteal reconstitution underwent attempted remote endarterectomy with a ring cutter system combined with primary stenting of the distal end point. Analysis was performed in a prospective manner with patency rates determined by Kaplan-Meier life-table analysis.

RESULTS

The indication for operation was claudication in 8 patients, rest pain in 6, and tissue loss in 3. Initial technical success was achieved in 11 patients (65%). Reasons for technical failure included SFA perforation (4), inability to traverse a calcified/diseased segment (1), and inability to retract/remove the ring cutter (1). Life-table analysis of all patients revealed a primary patency at 1 year of 26% +/- 11%. Primary-assisted patency was 38% +/- 12% at 1 year, with 59% of patients ultimately requiring surgical bypass grafting. In patients in whom initial technical success was achieved, the 1-year primary and primary-assisted patency rates were 40% and 59%, respectively. There were four reocclusions requiring surgical revascularization with below-knee popliteal (2) or tibial (2) bypass grafting, 1 symptomatic restenosis requiring repeat angioplasty, and 1 symptomatic restenosis treated conservatively.

CONCLUSION

The results of endovascular SFA endarterectomy were disappointing, with technical success in less than two thirds of patients and a 1-year primary patency of only 26%. Remote SFA endarterectomy appears less effective than above-knee femoropopliteal bypass grafting, and after early failure, patients may require more distal revascularization for limb salvage.

Early results of infragenicular revascularization based solely on duplex arteriography

PURPOSE

Recent reports have both advocated and questioned the utility of duplex arteriography (DA) as the sole preoperative imaging modality for planning infragenicular revascularization. This study compares the outcome of patients with critical limb ischemia who underwent infragenicular vein grafts on the basis of DA alone versus conventional preoperative contrast arteriography (CA).

METHODS

The study group is composed of 23 consecutive patients who underwent infragenicular vein bypass grafting solely on the basis of preoperative DA from 1998 to 1999. They were compared with 50 consecutive patients who underwent infragenicular vein bypass grafting after CA from 1996 to 1998. Peak systolic velocity and end-diastolic velocity of potential target arteries were recorded during DA studies. In situ saphenous vein grafts were used preferentially, and technical adequacy of all grafts was assessed with completion duplex or arteriography.

RESULTS

DA and CA groups were comparable on the basis of age and risk factors. In one limb (4%), the target artery selected by DA was abandoned because of dense calcification. No other revision in target or inflow artery was required on the basis of intraoperative completion studies. At 1 year, primary graft patency (78% vs 70%, P =.72) and limb salvage (70% vs 81%, P =.21) were comparable between the two groups. In the DA group, mean preoperative target artery peak systolic velocity in patent versus failed grafts was 49 +/- 18 cm/s versus 31 +/- 9 cm/s (P =.04), whereas mean end-diastolic velocity was 22 +/- 7 cm/s versus 14 +/- 8 cm/s (P =.08).

CONCLUSION

Infragenicular revascularization directed by DA alone provides early graft patency and limb salvage rates comparable to similar procedures that are based on CA. Preoperative DA target artery velocities may predict outcome and improve target selection. These initial results justify further clinical testing of DA as the primary imaging modality for planning infragenicular vein grafts.

Pedal branch artery bypass: a viable limb salvage option

PURPOSE

We reviewed our experience with pedal branch artery (PBA) bypass to confirm the role of these target arteries for limb salvage and to identify patient and technical factors that may be associated with graft patency and limb salvage.

METHODS

In this retrospective study we analyzed 24 vein grafts to PBAs performed from 1988 to 1998 for limb salvage in 23 patients who had no suitable tibial, peroneal, or dorsal pedal target arteries. These PBA grafts were compared with 133 perimalleolar posterior tibial, defined at or below the ankle, or dorsalis pedis bypass grafts performed contemporaneously; the Kaplan-Meier life table was used in the analysis of graft patency and limb salvage. Life table analyses and logistic regression analysis of prognostic patient variables were also performed.

RESULTS

The PBA bypass represented 3% of infrainguinal revascularizations for chronic critical limb ischemia at our institution over the study period. Patients who received PBA bypasses were more likely to be male (92% vs. 69%, P =.02) with lower incidences of overt coronary artery disease (33% vs. 50%, P =.12) and stroke (0% vs 15%, P =.04), and a higher incidence of end-stage renal disease (21% vs 8%, P =.06) than those undergoing perimalleolar bypass. Seventeen percent of PBA bypasses were performed with the anterior lateral malleolar artery, a vessel not previously described as a common bypass target. Two-year primary patency and limb salvage for PBA versus perimalleolar bypass was 70% versus 80% (P =.16) and 78% versus 91% (P = .28), respectively. Patency and limb salvage rates were no different in bypasses with above-knee or below-knee inflow arteries.

CONCLUSION

An autogenous vein bypass to the PBA, though rarely required, provides acceptable primary patency and limb salvage when compared with perimalleolar tibial artery bypass when no suitable, more proximal target arteries are available. The PBA bypass should be considered before major amputation is undertaken.

Predicting outcome of angioplasty and selective stenting of multisegment iliac artery occlusive disease

BACKGROUND

Patients who require angioplasty and stenting of multiple iliac arterial segments often require reintervention to maintain long-term patency. Morphologic predictors and causes of failure are unknown. The purpose of the current study was to define arteriographic predictors of angioplasty and selective stent failure in the treatment of multisegment iliac occlusive disease.

METHODS

All iliac segments (two common and two external) of 75 patients who underwent angioplasty and selective stent placement for multisegment iliac occlusive disease (>/= two segments) were scored through use of a modification of the Society of Cardiovascular and Interventional Radiology classification for iliac angioplasty (0 = no lesion; 4 = most severe). Total iliac score was calculated by summing scores from each segment. A separate external iliac score was calculated by adding only the external iliac scores. Arteriograms were reviewed initially and at the time of lesion recurrence and stratified by lesion location and previous intervention.

RESULTS

The area of previous endovascular intervention was the site of recurrence in 75% of patients. New lesions, presumably a result of progressive atherosclerosis, occurred in 15% of patients, and lesions occurred in both new and previously treated iliac segments in 10% of patients. Only the external iliac score was an independent predictor of failed endovascular therapy despite reintervention. For patients with an external iliac score of 2 or less, the endovascular primary-assisted patency rates at 6, 12, and 24 months were 96%, 92%, and 89%, respectively. This was improved in comparison with the 90%, 63%, and 45% patency rates observed in patients with an external iliac score of 3 or more (P =.001). Patients with an external iliac score of 3 or more had a significantly lower incidence of hemodynamic and clinical improvement after intervention and a threefold higher need for surgical inflow procedures than patients with an external iliac score of 2 or less.

CONCLUSIONS

Lesion formation after treatment of multisegment iliac occlusive disease typically occurs in areas of prior intervention. The extent of external iliac disease can be used to stratify patients with multisegment iliac occlusive disease who will likely respond to endovascular treatment with a durable result. Patients with extensive external iliac disease (score >/= 3) have poor results after angioplasty and selective stenting as applied in this study, even with endovascular reintervention. They are ideal subjects for prospective comparative studies of competing initial therapies, including stenting, endografting, and aortobifemoral bypass grafting.

The durability of endovascular treatment of multisegment iliac occlusive disease

PURPOSE

The effectiveness of endovascular treatment of multisegment iliac occlusive disease (involving two or more common and/or external iliac arteries) was determined.

METHODS

All patients who underwent angioplasty or stenting of at least two separate iliac artery segments were identified. Demographic data were recorded. Technical success, hemodynamic success, and aortoiliac primary and primary-assisted patency were analyzed by using the Society for Vascular Surgery and International Society for Cardiovascular Surgery (SVS/ISCVS) criteria. Multivariate, life table analysis was used as a means of determining outcome predictors.

RESULTS

Eighty-seven patients underwent 207 iliac artery angioplasties and 115 iliac artery stents, which were performed in 210 iliac segments for disabling claudication in 60% of cases, for rest pain in 17% of cases, and for tissue loss in 23% of cases. Two iliac segments were treated in 64% of patients, three segments were treated in 28% of patients, and four segments were treated in 8% of patients. The complication rate was 11%. Initial hemodynamic success was achieved in 72% of cases. Clinical improvement occurred in 88% of patients. Subsequent endovascular reintervention was required in 29% of patients, whereas surgical inflow procedures were required in 14% of patients to maintain aortoiliac patency. The mean time from the primary intervention to the first reintervention was 10 +/- 3 months. At 6, 12, and 36 months after intervention, the primary patency rates of the aortoiliac segment were 76%, 61%, and 43%, respectively, and the primary assisted patency rates were 95%, 87%, and 72%, respectively. Only the presence of an external iliac artery stenosis adversely affected both primary and assisted-primary patency. At 6, 12, and 36 months, the aortoiliac primary patency rates in patients without the presence of an external iliac artery stenosis were 88%, 78%, and 69%, respectively, compared with 68%, 47%, and 18%, respectively, in patients with external iliac artery lesions (P <. 0001).

CONCLUSION

Endovascular therapy for multisegment aortoiliac occlusive disease has acceptable patency rates; however, reintervention is often needed. The presence of external iliac artery disease is a significant predictor of poor outcome.

Lower extremity bypass using only duplex ultrasonography: is the time now?

Imaging for lower extremity arterial bypasses continues to evolve as distal target vessels are more frequently small infragenicular arteries. For these procedures to be properly planned and executed, accurate anatomic knowledge of the lower extremity arterial system and potential venous conduits is essential. The utility of current imaging methods for planning lower extremity revascularization is examined, including the relatively recent use of duplex arterial mapping. Arteriography is a poor "gold standard" in many cases of iliac and infrainguinal arterial occlusive disease. Duplex arterial scanning can be performed successfully in patients being considered for lower extremity revascularization. Patients with isolated stenoses or short occlusions, particularly those above the inguinal ligament, may be identified in whom percutaneous endovascular therapy is appropriate, depending on their clinical presentation. Patients with more severe disease may be taken to the operating room, where the quality of the inflow is evaluated with arterial pressure measurement. If the inflow pressure is not equal to systemic pressure, arteriography with pullback pressure measurements can be performed, and the responsible lesion can be identified and appropriately treated. Once inflow obstruction has been corrected, intraoperative outflow arteriography is performed. If duplex arterial mapping does not demonstrate a distal site for bypass, arteriography should be performed, as a preoperative or intraoperative study, before considering amputation. This approach should decrease the cost and complications of lower extremity revascularization while allowing treatment planning for lower extremity vascular occlusive disease to be based on accurate anatomic and physiological data.

Mesenteric and celiac duplex scanning: a validation study

PURPOSE

To validate the accuracy of previously established duplex ultrasound criteria for > or =50% superior mesenteric artery (SMA) and celiac artery (CA) stenosis by comparison with arteriography.

METHODS

Duplex criteria established retrospectively in our laboratory in 1991 identified an end-diastolic velocity (EDV) > or =45 cm/sec, or no flow signal, as highly sensitive (100%) and specific (92%) indicators for SMA stenosis > or =50% or occlusion. EDV was more accurate (95%) than peak systolic velocity (PSV), which had a maximal accuracy of 86% at a PSV > or =300 cm/sec, with low sensitivity (62%), but high specificity (100%). For CA, accurate velocity thresholds were not identified, but we subsequently noted that retrograde common hepatic artery flow direction from SMA collateral was highly predictive of severe CA stenosis or occlusion. Since publication of those findings, 243 mesenteric duplex scans were performed for clinical evaluation of suspected chronic mesenteric ischemia. Angiographic confirmation was available for a subset of 46. SMA and CA diameters were measured on lateral aortograms by observers blinded to the duplex results, and the original duplex diagnostic criteria were tested for accuracy. In addition, receiver operator characteristic curve analysis was performed on the velocity data to identify the most accurate velocity thresholds in the new data.

RESULTS

Duplex was technically adequate in 98% of SMA, 96% of CA, and 89% of hepatic arteries, and arteriograms were adequate in 100% of SMA and 98% of CA. For the SMA, EDV > or =45 cm/sec again provided the best sensitivity (90%), specificity (91%), positive predictive value (90%), negative predictive value (91%), and overall accuracy (91%). As in the retrospective study, PSV > or =300 cm/sec provided low overall accuracy (81%), low sensitivity (60%), but high specificity (100%). Lowering the PSV threshold improved sensitivity but reduced accuracy. For CA, retrograde common hepatic artery flow direction was 100% predictive of severe CA stenosis or occlusion. Velocity data in CA provided accuracy not found in the original study. EDV > or =55 cm/sec or no flow signal had best overall accuracy (95%) with high sensitivity (93%) and specificity (100%). PSV > or =200 cm/sec or no signal also had excellent accuracy (93%), sensitivity (93%), and specificity (94%). In addition, three of four anatomic anomalies were correctly identified by duplex. These included one right hepatic and one common hepatic artery originating from the SMA, and one common celiacomesenteric trunk.

CONCLUSION

This validation analysis confirms that duplex velocity criteria are accurate in the identification of mesenteric occlusive disease. Retrograde common hepatic artery flow direction correctly predicts severe CA stenosis or occlusion. Duplex ultrasound may also identify mesenteric anatomic variants that can influence study interpretation.

Fate of the contralateral leg after infrainguinal bypass

PURPOSE

To identify variables predictive of the need for future vascular intervention in a leg contralateral to one currently undergoing infrainguinal bypass.

METHODS

We reviewed the records of 450 consecutively treated patients undergoing infrainguinal bypass for occlusive disease to examine the outcome of a previously untreated contralateral leg. Patients with coexistent contralateral limb-threatening ischemia at the time of initial ipsilateral operation were excluded, as were patients with bilateral disease who underwent a staged contralateral procedure within 3 months of the ipsilateral operation. This yielded a study cohort of 383 patients with no anticipated intervention in the contralateral leg who were followed for a mean value of 38 months. Patient survival and subsequent intervention in the contralateral leg were examined with life-table and regression analysis.

RESULTS

Mean age of the patients was 68 years; 60% were men; 54% had diabetes; and 50% had coronary artery disease. The initial ipsilateral operation was performed for limb threat in 90% of instances. Twenty percent of patients subsequently needed intervention in the contralateral leg (infrainguinal bypass 83%, primary major amputation 17%). According to life-table analysis, 30% of patients needed intervention at 5 years, and the overall survival rate was 51% at 5 years. Multivariate analysis indicated that the need for future contralateral intervention was independently predicted with the following four risk factors: diabetes (relative risk [RR] 2.4x), coronary artery disease (RR 1.8x), lower initial ankle-brachial index (RR 2.1x with ankle-brachial index less than 0.7), and younger age (RR 2.2x if age less than 70 years). Regression models predicted the need for contralateral intervention for only 8% of patients at 5 years when none of these risk factors was present but for 67% when all risk factors were present.

CONCLUSION

The fate of the contralateral leg after infrainguinal bypass is affected by diabetes, coronary artery disease, contralateral ankle-brachial index, and age at initial ipsilateral bypass. The effect of these risk factors is additive in prediction of the likelihood of future intervention. Knowledge of these factors may help identify instances in which the contralateral greater saphenous vein will be important for future limb salvage and also determine which patients need more careful follow-up care.

Longitudinal comparison of dialysis access methods: risk factors for failure

PURPOSE

To compare dialysis access patency rates and identify risk factors for failure.

METHODS

All access procedures at our institution from 1987 to 1996 were reviewed. Primary procedures were surgically implanted dual-lumen central venous hemodialysis catheters (SIHCs), peritoneal dialysis catheters (PDCs), arteriovenous fistulas (AVFs), and prosthetic shunts (PTFEs).

RESULTS

Five hundred eighty-five primary procedures (236 PTFEs, 87 AVFs, 112 SIHCs, and 150 PDCs) and 259 secondary procedures (215 PTFEs, 14 AVFs, 0 SIHCs, and 30 PDCs) were performed on 350 patients. By life table analysis, SIHCs exhibited the lowest primary patency rate (9% at 1 year; p < 0.0001), whereas PDCs had the highest primary patency rate (57% at 1 year; p < 0.02). The primary patency rates of AVFs and PTFEs was similar, with 43% and 41% 1-year patency rates, respectively (p = 0.70). Less-stringent reporting methods would have increased apparent 1-year patency rates by 9% to 41%. With regard to secondary patency, there was no significant difference between PTFEs and PDCs, with 1-year patency rates of 59% and 70%, respectively (p = 0.62), but PTFEs were more frequently revised. In addition, there was no significant difference between AVF and PTFE secondary patency rates, with 1-year patency rates of 46% and 59%, respectively. Early differences in patency rates for AVFs, PTFEs, and PDCs diminished over time, and at 4 years AVFs had the best secondary patency rate (p = 0.6). The most common reasons for access failure were: PTFEs, thrombosis; AVFs, thrombosis and failure to mature; SIHCs, inadequate dialysis; PDCs, infection and inadequate exchange. By regression analysis, a history of a previous unsalvageable PTFE was the only significant risk factor for failure of a subsequent PTFE (p < 0.01), and the risk of graft failure increased exponentially with the number of previous PTFE shunts. Diabetes was the only significant risk factor for failure of PDCs (p < 0.02; odds ratio, 2.0).

CONCLUSIONS

The patency rate for PTFEs is similar to that for AVFs, but AVFs require fewer revisions. When replacing a failed access graft, the risk of PTFE failure increases with the number of prior unsalvageable PTFE shunts. PDCs have excellent patency rates, but failure rates are doubled in patients with diabetes. Because of poor patency rates and inadequate dialysis flow rates, SIHCs should be avoided when possible. Reporting methods dramatically affect apparent patency rates, and reporting standards are needed to allow meaningful comparisons in the dialysis access literature.

Thrombolysis of occluded infrainguinal vein grafts: predictors of outcome

PURPOSE

The purpose of this study was to identify factors that influence graft patency and limb salvage rates after thrombolysis of occluded infrainguinal vein grafts.

METHODS

The records of patients who underwent percutaneous catheter-directed thrombolysis of occluded infrainguinal vein bypass grafts at our institution between 1985 and 1995 were reviewed. Life table analysis was used to determine survival and patency differences. Univariate and multivariate analyses were used to identify the patient-specific factors that affected outcomes.

RESULTS

Forty-four patients with 44 thrombosed infrainguinal vein grafts underwent thrombolysis with urokinase. The thrombolysis-related mortality rate was 2%, and nonfatal complications occurred in 16%. Thrombolysis was unable to restore graft patency in 25% of grafts (11 of 44). Of the remaining 33 successfully lysed grafts, 88% required adjunctive surgery or percutaneous transluminal angioplasty after thrombolysis. Overall, the primary graft patency rate was 25% at 1 year and 19% at 2 years after thrombolysis. Considering only successfully lysed grafts, the primary patency rate improved to 34% at 1 year and 25% at 2 years. Multivariate analysis revealed that the graft patency rate was substantially better in patients without diabetes and in vein grafts that had been in place for longer than 12 months (p < 0.01). The limb salvage rate was significantly improved by successful thrombolysis (63% at 2 years vs 31% if lysis failed; p < 0.01). The patient survival rate was high-89% 2 years after thrombolysis.

CONCLUSIONS

Even with adjunctive therapy, vein graft thrombolysis is unlikely to yield durable patency overall. However, successful thrombolysis improves limb salvage rates and may be beneficial in patients without diabetes who have mature vein grafts but who do not have options for other autogenous revascularization procedures.

Superficial femoral artery stenoses: characteristics of progressing lesions

PURPOSE

The purpose of this study was to assess the effect of superficial femoral artery (SFA) stenosis morphologic characteristics and lesion location on the rate of atherosclerotic disease progression.

METHODS

We identified 19 patients who required arteriography for treatment of critical leg ischemia and who had previously undergone arteriography of that leg when minimal or no symptoms were present. These initial incidental arteriographic evaluations were performed during evaluation of arterial disease in another vascular bed from 4 to 81 months (mean, 32 months) previously. Distinct SFA stenoses or occlusion on the final arteriogram (n = 98) were characterized by their location, length, stenosis severity, and morphologic appearance on the initial arteriogram. The contribution of patient-specific risk factors to disease progression was also assessed.

RESULTS

Stenosis progression occurred independently among multiple lesions within the same patient (negligible intraclass correlation coefficient, r = 0.06). Lesions in the adductor canal region were more likely to occlude than lesions elsewhere in the SFA (adjusted odds ratio = 10.7; p = 0.03). Severity of initial lesion stenosis also was predictive of occlusion (adjusted odds ratio = 1.8; p = 0.04). However, most progressing lesions (93%) actually arose in areas of initially mild disease (stenoses < 50%) despite more severe initial lesions elsewhere. Increasing age (p = 0.023) and previous contralateral leg bypass (p = 0.036) were also associated with increasing rates of lesion progression. Smooth-asymmetric lesions progressed 11% more slowly than other lesion types (p = 0.003).

CONCLUSIONS

Our analysis of atherosclerotic SFA lesion progression in patients with critical ischemia shows that initial stenosis severity was associated with higher occlusion rates and that smooth-asymmetric lesions progressed more slowly than lesions with other morphologic characteristics. Severe stenoses usually arose from minimally diseased regions and progressed more rapidly than preexisting, more highly stenotic lesions. Most SFA occlusions resulted from disease progression in the adductor canal region whether or not antecedent lesions were seen on arteriography and whether or not more severe stenoses were initially present elsewhere. Increased age and history of previous contralateral bypass were patient-specific predictors of lesion progression.

Cost-effectiveness of carotid endarterectomy in asymptomatic patients

PURPOSE

The purpose of this study was to determine the cost-effectiveness of carotid endarterectomy for treating asymptomatic patients with > or = 60% internal carotid stenosis, based on outcomes reported in the Asymptomatic Carotid Atherosclerosis Study (ACAS).

METHODS

A cost-effectiveness analysis was performed using a Markov decision model in which the probabilities for base-case analysis (average age, 67 years; 66% male; perioperative stroke plus death rate, 2.3%; ipsilateral stroke rate during medical management, 2.3% per year) were based on ACAS. The model assumed that patients who had TIAs or minor strokes during medical management crossed over to surgical treatment, and used the NASCET data to model the outcome of these now-symptomatic patients. Average cost of surgery ($8500), major stroke ($34,000 plus $18,000 per year), and other costs were based on local cost determinations plus a review of the published literature. Cost-effectiveness was calculated as the incremental cost of surgery per quality-adjusted life year (QALY) saved when compared with medical treatment, discounting at 5% per year. Sensitivity analysis was performed to determine the impact of key variables on cost-effectiveness.

RESULTS

In the base-case analysis, surgical treatment improved quality-adjusted life expectancy from 7.87 to 8.12 QALYs, at an incremental lifetime cost of $2041. This yielded an incremental cost-effectiveness ratio of $8,000 per QALY saved by surgical compared with medical treatment. The high cost of care after major stroke during medical management largely offset the initial cost of endarterectomy in the surgical group. Furthermore, 26% of medically managed patients eventually underwent endarterectomy because of symptom development, which also decreased the cost differential. Sensitivity analysis demonstrated that the relative cost of surgical treatment increased substantially with increasing age, increasing perioperative stroke rate, and decreasing stroke rate during medical management.

CONCLUSION

For the typical asymptomatic patient in ACAS with > or = 60% carotid stenosis, our results indicate that carotid endarterectomy is cost-effective when compared with other commonly accepted health care practices. Surgery does not appear cost-effective in very elderly patients, in settings where the operative stroke risk is high, or in patients with very low stroke risk without surgery.

Carotid duplex criteria for a 60% or greater angiographic stenosis: variation according to equipment

PURPOSE

The purpose of this study was to evaluate the carotid duplex criteria for a > or = 60% angiographic internal carotid artery (ICA) stenosis and the degree of variation among duplex scanners.

METHODS

Carotid duplex criteria for a > or = 60% angiographic stenosis were evaluated in two ICAVL-accredited vascular laboratories with different brands of duplex scanners (Siemens-Quantum and Diasonics in Laboratory A, ATL and Diasonics in Laboratory B). Analysis was performed for 360 carotid bifurcations in 180 consecutive patients who had concurrent angiographic and duplex evaluation. Blinded angiogram evaluation was performed with precision electronic calipers on magnified views, with stenosis calculated by criteria of the Asymptomatic Carotid Atherosclerosis Study and the North American Symptomatic Carotid Endarterectomy Trial. Duplex data included internal carotid artery peak systolic velocity (ICA PSV), ICA end-diastolic velocity, and the ratio of ICA PSV to common carotid artery (CCA) PSV (ICA/CCA ratio).

RESULTS

The most accurate determination of a > or = 60% ICA stenosis was obtained with ICA/CCA ratio and ICA PSV, but the optimal threshold differed for all four scanners. The optimal ICA/CCA ratio varied from 2.6 to 3.3, and the optimal ICA PSV varied from 190 to 240 cm/sec. All four scanners produced criteria that give a positive predictive value > 90% while maintaining accuracy at > or = 90%. Logarithmic transformation of duplex variables created a linear relationship between duplex values and angiographic stenosis, allowing statistical evaluation of scanner operating characteristics by linear regression analysis and analysis of covariance. This analysis revealed that the mathematic equation relating duplex values with angiographic percent stenosis was statistically different for one of the four scanners (p < 0.05). Scanner differences did not appear to be due to technologists, because the regression lines were nearly identical for the two Diasonics scanners despite use by different technologists. Ignoring the significant difference in operating characteristics for one of the four scanners would result in a mean error for predicting a 60% stenosis of 14% to 18% (equating a 46% or 78% stenosis with a 60% stenosis).

CONCLUSIONS

We conclude that the correlation of duplex data with angiographic percent stenosis and the duplex criteria for a > or = 60% stenosis are machine-specific. Regression analysis can determine whether apparent differences are due to chance or significant differences in scanner characteristics. Future studies should include regression analysis according to equipment type.

Observation on the value of erythrocyte membrane fatty acids in the discrimination of hypothyroidism

A computer-based 3-dimensional representation of two erythrocyte membrane saturated fatty acids (hexadecanoic acid, 16:0 and octadecanoic acid, 18:0), serum cholesterol and thyroid stimulating hormone (TSH) was performed in 26 hypothyroid patients and in 10 control subjects. The result indicates that a three-dimensional representation of grouped data discriminates normal people from individuals with hypothyroidism in a small population of highly selected cases.

Use of inferior vena cava filters in the Medicare population

To examine the use of inferior vena cava (IVC) filters, we performed a population-based study using a 5% random sample of the United States Medicare population (1.25 million persons). Filter placement and its timing relative to diagnosis of venous thromboembolism (VTE) were determined using both hospital and physician Medicare billing codes after detailed review of large samples of complete individual claims records. Comorbid conditions and mortality were also noted. From July 1986 through June 1989, a total of 806 patients in the sample population received IVC filters. Mortality rates after filter placement were high: 16% during initial hospitalization, 32% within 6 months of filter placement, and 48% after 2 years. However, only 3 (1%) of 423 patients who underwent filter placement without the diagnosis of pulmonary embolism (PE) suffered PE within 1 year of filter placement. Use of IVC filters increased significantly over the study period (p < 0.001). Rates of filter placement among the nine census divisions of the United States differed significantly (p < 0.001). An East-West trend was notable with the highest rate (37 filters/100,000 enrollees/yr) in New England, as compared with 14 filters/100,000 enrollees/yr in the Pacific Division. No explanation for these regional differences was evident after patient demographics and comorbidity were examined. Vena cava filters prevent PE for at least 1 year after placement. The frequency of IVC filter use in elderly patients is increasing and varies substantially by region. Although reasons for these trends are unclear, these findings suggest the need for uniform practice guidelines for IVC filter placement.

Vein adaptation to the hemodynamic environment of infrainguinal grafts

PURPOSE

Although arteries appear to remodel in response to changes in hemodynamic parameters such as shear stress, little is known about functioning human vein grafts. This study was designed to explore diameter changes in human saphenous vein grafts after infrainguinal bypass.

METHODS

We used duplex ultrasonography to measure hemodynamic variables that might affect the diameter of 48 in situ saphenous vein grafts during the first year after infrainguinal arterial bypass. Volumetric flow rate, average velocity, peak systolic velocity, and vein diameter in the proximal and distal thirds of these grafts were each measured at 1 week and at 3, 6, and 12 months after operation. Veins were divided into three groups based on initial size (1 week after bypass) in the below-knee segment: small, < 3.5 mm diameter; medium, 3.5 to 4 mm diameter; and large, > 4 mm diameter.

RESULTS

Distal vein diameters at 1 week for small, medium, and large grafts were 2.9 +/- 0.1, 3.7 +/- 0.1, and 4.3 +/- 0.1 mm, respectively (p < 0.001), but by 12 months these diameters were 3.6 +/- 0.2, 3.8 +/- 0.2, and 3.9 +/- 0.2 mm, respectively (p = 0.54). Large veins decreased in diameter, whereas small veins increased in diameter, as confirmed by linear regression of percent change in diameter versus initial vein graft diameter (r = -0.62, p < 0.001). Volumetric flow rate, peak systolic velocity, and shear stress also tended to approach uniform values over time. Of the hemodynamic variables studied, the best predictor of diameter change was shear stress (linear regression of percent change in diameter vs shear stress, r = 0.67, p < 0.001). Veins with a diameter increase greater than 10% over time had significantly higher initial shear stress than veins with a diameter decrease greater than 10% over time (28.6 +/- 3.8 vs 13.1 +/- 1.8 dynes/cm2, p < 0.01), whereas initial volumetric flow rates in these two groups were similar (135 +/- 23 vs 130 +/- 15 ml/min).

CONCLUSIONS

Infrainguinal in situ vein graft diameter, volume flow rate, peak systolic velocity, and shear stress all tend to stabilize at uniform values regardless of the initial vein graft diameter. Of the hemodynamic variables studied, shear stress is most strongly associated with the change in diameter over time. Thus human saphenous vein appears to be capable of adapting to its hemodynamic environment after arterial grafting by modulating diameter to normalize shear stress.

Femorofemoral versus aortobifemoral bypass: outcome and hemodynamic results

PURPOSE

Femorofemoral bypass (FFB) is used in selected patients when aortobifemoral bypass (AFB) is believed to be inappropriate because of high operative risk or predominantly unilateral iliac artery occlusive disease. We examined concurrent patients who underwent either FFB or AFB to better understand the appropriate use of FFB.

METHODS

The characteristics and outcomes of patients who underwent FFB and AFB during 1986 to 1991 at our institution were retrospectively reviewed. Primary measures of outcome included patient survival, graft patency, limb salvage, and hemodynamic performance of FFB and AFB. Further analysis was performed after substratification for low versus high risk and claudication versus limb threat as the indication for surgery.

RESULTS

FFB was performed in older patients with more medical comorbidities when compared with AFB. Long-term graft patency was inferior after FFB compared with AFB (60% vs 85% at 3 years, p < 0.01). However, both FFB and AFB achieved limb salvage in more than 85% of patients at 3 years. When patients at low risk undergoing nonemergency AFB were compared with patients at low risk who underwent FFB and who had no contraindication to AFB, FFB proved inferior to AFB as measured by graft patency (primary patency 61% vs 87% at 3 years, p < 0.03) and hemodynamic performance (predicted ankle-brachial index with perfect outflow 0.82 after FFB vs 1.03 after AFB). On the basis of a detailed analysis of patient and graft risk factors, we could not explain the inferior patency rate of FFB, although our analysis suggested that inadequate inflow may contribute.

CONCLUSIONS

FFB is inferior to AFB as measured by patency and hemodynamic function. This inferior performance is independent of indications for FFB. AFB should remain the standard therapy for patients at low risk with iliac occlusive disease, but FFB provides adequate function and limb salvage in patients at high risk.

Functional health and well-being in patients with severe atherosclerotic peripheral vascular occlusive disease

Functional health and sense of well-being are known to be adversely affected by chronic illness. The extent to which peripheral vascular occlusive disease (PVOD) alters these factors independent of other comorbid conditions is unknown. Sixty patients with PVOD severe enough to have required aortobifemoral bypass (AFB) between 1985 and 1990 were selected for evaluation. Although all were heavy smokers and 20% had suffered previous myocardial infarction, all had adequate cardiopulmonary function to survive AFB. The SF-20 questionnaire, validated in the Medical Outcomes Study (MOS), was used to evaluate patients' functional health and well-being at least 6 months after AFB. All grafts were patent at the time of questionnaire completion. Three measures of functional health (physical function, role function, and bodily pain) and three measures of well-being (mental health, health perception, and social function) were scored from SF-20 responses using the MOS protocol. These PVOD patients were then compared to MOS norms for patients without any chronic disease, to MOS norms adjusted for age and other comorbidities of the PVOD patients sampled, and to patients with congestive heart failure or recent myocardial infarction. Physical function, role function, and health perception were worse and bodily pain greater in patients with severe PVOD after surgical treatment as compared with MOS patients even after adjustment for comorbidities. Decrements in physical function, role function, and health perception for PVOD patients were comparable to MOS patients with congestive heart failure or recent myocardial infarction, whereas level of bodily pain was worse in PVOD patients than in these other groups. After adjustment for comorbidities, social function and mental health were not independently affected by PVOD. Functional health and well-being were not significantly different when PVOD patients with limb threat were compared to those with claudication. Severe PVOD is associated with decrements in functional health and well-being comparable to or greater than other severe chronic illness, even after successful revascularization. Further study is needed to examine the effect of revascularization on functional health.

Pedal bypass versus tibial bypass with autogenous vein: a comparison of outcome and hemodynamic results

PURPOSE

Autogenous vein grafts to infrapopliteal arteries performed for chronic limb-threatening ischemia between 1984 and 1991 were reviewed to determine whether bypasses to pedal arteries produce results comparable to those obtained after supramalleolar tibial or peroneal bypasses.

METHODS

Pedal bypass (dorsal pedal, n = 41; below-ankle posterior tibial, n = 12) was performed only if a suitable tibial target artery was not available. These grafts were compared with tibial (including peroneal) bypass grafts (n = 203). All grafts were placed for rest pain (23%) or established tissue loss (77%).

RESULTS

Patients requiring pedal bypass were more likely to have diabetes and congestive heart failure but less likely to have a history of smoking. Age, gender, previous myocardial infarction, and other comorbidities were similar in the two groups. Operative mortality rates (30 days) were higher for pedal than tibial bypasses (9% vs 2%; p = 0.021), possibly reflecting the higher prevalence of diabetes, congestive heart failure, and more advanced systemic atherosclerosis associated with severe tibial artery disease. Most grafts were in situ saphenous vein (70% pedal vs 79% tibial). Life-table 3-year primary graft patency (58% pedal vs 61% tibial), secondary patency (82% pedal vs 79% tibial), limb salvage (92% pedal vs 87% tibial), and patient survival (61% pedal vs 64% tibial) were comparable in the two groups. Improved assisted primary patency and secondary patency rates in both groups were primarily a result of revision of graft-threatening lesions detected with noninvasive graft surveillance before thrombosis. Mean postoperative ankle/brachial index was similar for pedal and tibial bypasses, whereas mean duplex-estimated graft flow was less for pedal grafts (88 +/- 10 ml/min vs 129 +/- 6 ml/min; p = 0.002). Pedal bypass represented 21% of our experience with infrapopliteal vein grafts for chronic limb-threatening ischemia and was required more frequently in diabetic patients. Operative mortality rates were higher in patients undergoing pedal bypass, suggesting that aggressive preoperative diagnostic studies and perioperative monitoring may be appropriate for this group. Long-term survival was similar.

CONCLUSION

We conclude that autogenous vein pedal bypass grafts provide hemodynamic results and limb salvage rates comparable to more proximal tibial bypasses in properly selected patients.

Surgical treatment of infrainguinal arterial occlusive disease in women

PURPOSE

This study reviewed the outcome of 131 women who underwent infrainguinal bypass in 150 limbs from 1984 to 1991 for limb-threatening ischemia (95%) or disabling claudication (5%).

METHODS

These women were compared with 209 men who underwent infrainguinal arterial reconstruction of 231 lower extremities for limb threat (89%) or claudication (11%) during the same interval. On average, women were 3 years older than men (mean age 72 vs 69 years, p < 0.005) but were less frequently cigarette smokers (56% women, 68% men, p < 0.05). Fifty-two percent of women had diabetes and 67% had hypertension, similar to the male patients. Infrainguinal disease distribution necessitated bypass to the above-knee popliteal artery in 10%, to the below-knee popliteal artery in 25%, and to the tibial or pedal arteries in 65% of women, comparable to the disease distribution in men. Autogenous vein grafts were performed in 90% of both groups.

RESULTS

Early postoperative (30-day) mortality was 4% for women and 2% for men (not significant). Life-table survival after 3 years, however, was only 54% in women, compared with 72% in men (p < 0.05). Multivariate analysis indicated that diabetes increased the mortality rate 2.5-fold in women, which was not true in men. Three-year life-table survival of women with diabetes was only 39%, compared with 78% in women without diabetes (p < 0.001). Primary graft patency in women was 59% at 1 year and 54% at 3 years, significantly less than the 73% and 70% graft patency rates observed in men (p < 0.005). Secondary graft patency improved in women to 75% and 69% after 1 and 3 years, but this was still significantly less than the secondary patency rates of 89% and 86% observed in men (p < 0.001). Multivariate analysis indicated that female sex decreased secondary graft patency 2.4-fold and was the only variable associated with graft failure. Cumulative 3-year limb salvage in women was 82%, not statistically different than the 89% limb salvage rate observed in men.

CONCLUSIONS

Women and men requiring arterial reconstruction for infrainguinal occlusive disease had comparable operative mortality and limb salvage rates, but long-term survival and graft patency were significantly reduced in women. Our results indicate that sex substantially influences the outcome of patients after infrainguinal bypass.

Current use of inferior vena cava filters

To study possible changes in the clinical use of inferior vena cava (IVC) filters caused by the introduction of percutaneous delivery systems, we reviewed all patients who underwent placement of IVC filters at our institution from 1988 to 1991. Eighty-four patients (52 men and 32 women) ranging in age from 18 to 90 years (mean 67 years) were identified. Filters were required because of contraindications to anticogulation in 64% anticoagulation failure in 25%, and preoperative prophylaxis in 11% of patients. The underlying disease was lower extremity deep vein thrombosis in 50% and pulmonary embolism in 45% of patients. Five percent of patients received prophylactic filters without documented thromboembolism. All filters were placed percutaneously by interventional radiologists, 77 through the common femoral vein and 7 through the internal jugular vein. Three types of filters were used. One procedure-related death occurred because of acute IVC occlusion. Fatal pulmonary embolism within 48 hours after filter placement was documented in one patient and suspected in one late death. No other clinically apparent pulmonary embolism or leg swelling occurred after filter placement. Minor complications related to filter placement occurred in 13 patients, but none required operative intervention. Analysis of complication rates of the three filter types was precluded by the small sample size. After a mean follow-up of 11 months, 42 patients (50%) had died of malignancy (n = 25), multisystem organ failure (MSOF; n = 7), cardiovascular events (n = 4), recurrent pulmonary embolism (n = 2), cerebrovascular events (n = 4), or an unknown cause (n = 1). Twenty-three patients (27%) died before hospital discharge.(ABSTRACT TRUNCATED AT 250 WORDS)

Pelvic blood flow following aortobifemoral bypass with proximal end-to-side anastomosis

Nine patients with end-to-side aortobifemoral bypasses were studied in the first year after surgery using color duplex imaging to determine the source of pelvic blood flow. No patient had clinical evidence of postoperative pelvic ischemia. Six of nine patients were found to have occluded distal aortas by duplex studies performed at a mean of 4.4 months postoperatively (range 0.8-8.2 months). Of those six patients, postoperative duplex examination demonstrated two with no common or external iliac blood flow, two with bilateral retrograde external iliac flow, and two with unilateral retrograde external iliac flow. Of the three patients with patent distal aortas, two had no demonstrable external iliac blood flow, while the third had continued antegrade flow through one external iliac and retrograde flow through the other. Analysis of preoperative arteriograms failed to reveal accurate predictors of postoperative distal aortic patency or retrograde iliac blood flow. Despite the preoperative assumption that prograde common iliac artery blood was required to prevent pelvic ischemia, distal aortic patency was maintained in only three of nine patients. In the six patients with prograde iliac blood flow, no ischemic symptoms were present, including two patients with complete absence of antegrade aortic or retrograde external iliac blood flow. Our observations indicate that assumptions which underlie the decision to perform end-to-side aortic anastomoses are often not borne out in the months following aortobifemoral bypass.

An unusual case of intermittent venous obstruction of the upper extremity

The axillary vein can be subject to intermittent obstruction from numerous anatomic structures such as the pectoralis minor and the scalenus anterior muscles. The diagnosis can be readily made on history and physical examination of the upper extremity, but it can be difficult to confirm by routine venogram done with the arm in the standard position at the side with full extension at the antecubital fossa. Positional venography with the arm fully abducted and flexion of that antecubital fossa allows for better definition of this extrinsic compression. In the case presented, a fascial band arising from the medial head of the biceps was compressing the axillary vein and was suspected on history and physical examination; it was confirmed with positional venography as noted. As in this case, it is important to make the diagnosis early, before thrombosis of the vein occurs, to minimize the associated morbidity. Transaxillary exploration was performed with excision of the band and complete resolution of the symptoms. Subsequent noninvasive studies were performed that showed complete resolution of the extrinsic axillary vein compression. Having a high suspicion of intermittent venous obstruction with early diagnosis and surgical correction of any extrinsic compression are the keys to a successful outcome in these patients.

Axillofemoral bypass: outcome and hemodynamic results in high-risk patients

Aortobifemoral bypass (AoFB) is the preferred method to provide lower extremity inflow. To determine whether axillofemoral bypass (AxFB) is an acceptable alternative for high-risk patients, we reviewed our results with these two operations. Between 1985 and 1990, 29 axillobifemoral and 5 axillounifemoral bypass procedures were performed preferentially because of severe associated medical illness in patients with severe aortoiliac occlusive disease. During the same interval, 107 patients received an AoFB for pure aortoiliac occlusive disease. Nearly all patients having AxFB and AoFB were heavy smokers, and the two groups had similar rates of hypertension and angina. However, other major risk factors were more frequently found in patients undergoing AxFB. Limb-threatening ischemia was more frequent and femoral artery occlusive disease was more severe in patients having AxFB. Anastomosis to the deep femoral arteries and concomitant infrainguinal bypass were more likely to be required in patients who had AxFB. Life-table patient survival at 3 years was 35% for AxFB versus 91% for AoFB (p less than 0.001). Primary patency at 3 years was 63% for AxFB versus 85% for AoFB (p = 0.032). Secondary patency was 74% for AxFB versus 94% for AoFB (p less than 0.001). However, all revised grafts in both groups were patent at 36 months, and only one revised AxFB graft was an ultimate failure. Limb salvage at 3 years was 76% for AxFB versus 97% for AoFB (p = 0.065). Nineteen of the 22 patients with AxFB who died during follow-up died with patent grafts. Hemodynamic performance of AxFB and AoFB were compared. Mean preoperative ankle-brachial index was higher in AoFB (0.50) than AxFB (0.38, p less than 0.001), but postoperative ankle-brachial index was much higher after AoFB (0.83) than AxFB (0.57, p less than 0.001). Even after adjustment for severity of outflow disease, postoperative ankle-brachial index was much better after AoFB than AxFB. Axillofemoral bypass was performed in older higher risk patients with more severe ischemia than those in the AoFB group. Hemodynamic performance was inferior and graft failure more common after AxFB. However, AxFB provided limb salvage in all but 2 of 22 patients who have died, and no survivor has had amputation because of graft failure. Axillofemoral bypass is an acceptable but hemodynamically inferior alternative to AoFB in properly selected high-risk patients with critical lower extremity ischemia who would likely not tolerate the more durable AoFB.

A blinded comparison of angiography, angioscopy, and duplex scanning in the intraoperative evaluation of in situ saphenous vein bypass grafts

Angiography, angioscopy, and duplex scanning have each been advocated for intraoperative assessment of in situ saphenous vein grafts. We compared these three modalities during operation in a prospective, blinded study during the construction of 20 femoral-infragenicular in situ saphenous vein grafts. Each modality was used and interpreted by a surgeon blinded to the results of the other studies. Abnormalities requiring intervention were defined as (1) patent vein side branches, (2) residual valve cusps, and (3) anastomotic stenoses greater than 30%. Criteria, specific to the modality, corresponding to each category were prospectively defined. Fourteen residual valve cusps, 49 patent vein branches, and 6 anastomotic stenoses were suggested by at least one modality. Nine residual valve cusps, 32 patent vein branches, and no anastomotic stenoses were actually found (and corrected) by direct inspection. Sensitivity of detecting patent side branches for angiography, duplex scanning, and angioscopy was 44%, 12%, and 66%, respectively. Both angiography and angioscopy were significantly more sensitive than duplex scanning for detection of unligated side branches (p less than 0.01). Sensitivity of detecting residual valve cusps was 22% (angiography), 11% (duplex scanning), and 100% (angioscopy). Angioscopy was significantly more sensitive than either duplex scanning or angiography in detection of residual valve cusps (p less than 0.01). Since no anastomotic stenoses were confirmed, the false-positive rates for stenosis detection were 20% for angiography, 10% for duplex scanning, and 0% for angioscopy. Time requirement was 17 to 20 minutes and did not differ among the three modalities. No stenosis or arteriovenous fistula has been detected in any graft by postoperative duplex surveillance (mean, 10-month follow-up).(ABSTRACT TRUNCATED AT 250 WORDS)

Duplex ultrasonography in the diagnosis of celiac and mesenteric artery occlusive disease

Duplex ultrasound criteria for the diagnosis of celiac and superior mesenteric artery (SMA) occlusive disease have not been well defined. We performed a blinded retrospective comparison of mesenteric duplex data with arteriography in 24 consecutive patients who underwent both studies. Arteriography revealed that eight superior mesenteric arteries were normal; five were minimally stenotic; eight had stenoses greater than or equal to 50%, and three were occluded. Nine celiac arteries were normal or minimally stenotic; 12 had stenoses greater than or equal to 50%, and three were occluded. Duplex scans were obtained after an overnight fast. In normal superior mesenteric arteries, peak systolic velocity (PSV) was 134 +/- 18 cm/sec and end-diastolic velocity (EDV) was 24 +/- 4 cm/sec. Superior mesenteric artery PSV in patients with minimal or no stenosis (171 +/- 22 cm/sec) was less than PSV in patients with severe (greater than 50%) stenosis (299 +/- 40 cm/sec, p = 0.006), and less than PSV in patients with patent superior mesenteric arteries who underwent revascularization (366 +/- 86 cm/sec, p = 0.017). Similarly, EDV was elevated in superior mesenteric arteries with severe stenosis (78 +/- 11 cm/sec, p = 0.001) and in patients who underwent revascularization (111 +/- 19 cm/sec, p less than 0.001) compared to those with less than 50% stenosis (30 +/- 6 cm/sec, p = 0.001). An EDV greater than 45 cm/sec was the best indicator of severe stenosis (sensitivity, 1.0; specificity, 0.92). Peak systolic velocity greater than 300 cm/sec was less sensitive (0.63), but highly specific (1.0) for severe superior mesenteric artery stenosis.(ABSTRACT TRUNCATED AT 250 WORDS)

The natural history of superficial femoral artery stenoses

Since the natural history of specific superficial femoral artery stenoses is not known, we examined progression rates of superficial femoral artery stenoses in 45 lower extremities found when arteriograms were obtained of 38 patients for symptomatic atherosclerotic disease in the opposite leg or abdomen. These initial superficial femoral artery arteriograms were compared with later arteriograms in 25 limbs, duplex scans in 27 limbs, and both modalities in 7 limbs. After a mean interval of 37 months, most superficial femoral artery stenoses (72%) did not progress. However, 12 superficial femoral artery stenoses progressed (28%; mean follow-up, 37 months, including 7 that occluded (17%). Superficial femoral artery stenoses progressed among patients who complained of symptom progression at a rate faster than that among asymptomatic patients (15.6%/year vs 3%/year; p = 0.006). Superficial femoral artery lesions also progressed more rapidly among patients whose contralateral superficial femoral artery was occluded (10%/year vs 1.6%/year; p = 0.04). By multivariate regression analysis, symptom progression and smoking history were predictive of superficial femoral artery stenosis progression. In the seven patients whose superficial femoral artery stenoses progressed to occlusion, the average rate of stenosis progression was 12%/year (maximum predicted rate, 30% per year by 95% confidence limit). These results indicate that superficial femoral artery stenoses usually progress with synchronous symptomatic deterioration. Other than symptom progression, only cumulative smoking history and contralateral superficial femoral artery occlusion could be associated with superficial femoral artery stenosis progression in this small series.(ABSTRACT TRUNCATED AT 250 WORDS)

Lack of diameter effect on short-term patency of size-matched Dacron aortobifemoral grafts

This study examined the relationship between graft diameter and subsequent patency in 79 patients who received Dacron aortobifemoral bypass grafts for aortoiliac occlusive disease between 1985 and 1989. Sixty-five percent of these patients were men, 25% were diabetic, and 94% were smokers, with an average age of 62 years. Patients were followed for a mean interval of 24 months. Life-table survival was 92% at 3 years. All surviving patients showed "significant" postoperative improvement by use of Society for Vascular Surgery/International Society for Cardiovascular Surgery combined clinical and vascular laboratory criteria. There were three early and five late graft thromboses. Primary and secondary life-table patencies were 85% and 92%, respectively, at 3 years. Dacron bifurcation grafts were selected to match the size of native arteries. Patients receiving small diameter grafts, defined as 12 mm (n = 9) and 14 mm (n = 39), were compared with patients receiving large diameter grafts of 16 mm (n = 26) and 18 mm (n = 5). Small diameter grafts were more likely to be used in women (p less than 0.01), but patient groups were otherwise comparable with respect to age, smoking history, diabetes, outflow status, operative indications, type of proximal anastomosis (end-to-end or end-to-side), location of distal anastomosis (common femoral vs deep femoral), type of graft construction (knitted vs woven), and functional result. Graft diameter did not influence life-table patency, which was 84% for small and 87% for large diameter grafts at 3 years (p = 0.74). Furthermore, none of the other variables listed above influenced graft patency.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of ibuprofen on cardiac performance during abdominal aortic cross-clamping

Decreased cardiac output and increased plasma thromboxane have been observed during aortic cross-clamping under general anesthesia. Amelioration of these changes has been reported by preoperative administration of cyclooxygenase inhibitors, but heterogeneity in patients' intravascular volume status has confounded analysis of the drugs' effects in previous studies. We studied hemodynamic conditions in 24 volume-loaded (pulmonary capillary wedge pressure greater than 10 mm Hg) patients undergoing abdominal aortic aneurysm repair under general plus epidural anesthesia, after preoperative double-blind administration of either ibuprofen 800 mg (n = 12) or placebo (n = 12). The hemodynamic response to aortic cross-clamping was similar in both groups. Pulse and mean arterial pressure remained unchanged; cardiac index decreased after aortic cross-clamping from 2.4 +/- 0.1 (mean +/- standard error of the mean [SEM]) to 2.1 +/- 0.1 1/min/m2 in the ibuprofen group and from 2.5 +/- 0.1 to 2.3 +/- 0.2 1/min/m2 in the placebo group (p less than 0.01 versus preclamp values in both groups, multivariate analysis of variance [MANOVA]), but improved after declamping. Both left and right ventricular stroke work indexes followed a similar pattern. Plasma 6-keto prostaglandin Fl alpha (6-k-PGF1 alpha) increased transiently from a baseline level of 304 +/- 44 to 2083 +/- 698 pg/ml plasma in mixed venous blood 30 minutes after incision in the placebo group (p less than 0.05), but no other significant change in plasma 6-keto prostaglandin Fl alpha or in thromboxane B2 occurred in either group at any other time.(ABSTRACT TRUNCATED AT 250 WORDS)

Oxygen-derived free radicals in hepatic ischemia and reperfusion injury in the rat

We have previously described a chronic, in vivo biochemical and histologic model of ischemia and reperfusion injury and wished to test the ability of superoxide dismutase, catalase and allopurinol to protect against the hepatocellular injury demonstrated by this model. Xanthine oxidase inhibitors given preoperatively produced a significant hepatocellular protective effect when compared with a comparable insult delivered to a cohort of control rats. The protection given seemed greater than that produced by pretreatment with free radical scavengers. Possible mechanisms for this observation are discussed. Investigations combining free radical scavengers with xanthine oxidase inhibitors may further define protection for warm hepatic ischemia and reperfusion injury.

Intragraft drug infusion as an adjunct to balloon catheter thrombectomy for salvage of thrombosed infragenicular vein grafts: a preliminary report

Early infragenicular vein graft thrombosis is associated with poor secondary patency, particularly when no correctable defect is identified. We have attempted to improve patency of thrombosed vein grafts by direct infusion of vasodilator and anticoagulant drugs after surgical thrombectomy. Among 212 infragenicular vein grafts, 16 (7.5%) required thrombectomy within 30 days of surgery (14 in situ saphenous vein, 1 composite vein, and 1 cephalic vein graft). Causes for failure were corrected in four (graft twist, intimal tear, suture failure, and external compression), resulting in prolonged patency. No cause for failure was apparent in the 12 remaining grafts after balloon catheter thrombectomy and arteriography. Two of these grafts occluded within 10 days despite multiple attempts at vein patch angioplasty, distal graft extension, and repeat thrombectomy with systemic anticoagulation. In the remaining 10 grafts, a small polyethylene catheter was placed in a proximal vein branch for direct intragraft drug infusion. Heparin (10 units/min) and nitroglycerin (50 micrograms/min) were the agents infused most frequently, for a mean duration of 52 hours after thrombectomy. Of these 10 infused grafts, 8 remained patent during a mean 17-month follow-up (range, 6 to 38 months). This was accomplished despite previous and repeated failures of thrombectomy and systemic anticoagulation in seven of these eight grafts. Two infused grafts rethrombosed within 30 days of infusion, resulting in amputation. No catheter-related complications occurred. Increased thrombogenicity, intimal injury, and spasm after balloon catheter thrombectomy may contribute to vein graft rethrombosis in the absence of technical defects. Direct intragraft infusion of nitroglycerin and heparin contributed to prolonged salvage of 80% of thrombosed vein grafts in this preliminary experience.

Variables that affect the expansion rate and outcome of small abdominal aortic aneurysms

Seventy-three patients with small (less than 6 cm in diameter) abdominal aortic aneurysms (AAAs) were selected for nonoperative management and followed up with sequential ultrasound size measurements. Fifty-four men and 19 women, 51 to 89 years of age (mean 70 years), had an initial mean AAA size of 4.1 cm (anteroposterior) x 4.3 cm (lateral) diameter, with a calculated elliptic cross-sectional area of 14.3 cm2. After a mean of 37 months of follow-up, AAA area increased at a mean rate of 20% per year (3 cm2 yr; 0.4 to 0.5 cm/yr diameter). Expansion rate was not affected by initial aneurysm size. During follow-up, only 3 patients (4%) required urgent operation (1 died), 26 patients (36%) died of non-AAA causes, and 26 patients (36%) underwent elective AAA repair because of progressive size increase (1 died). Elective operations were performed at the rate of 10% per year, when mean AAA size had increased to 22 cm2 (5.1 cm in diameter). Multiple regression analysis of clinical parameters available at presentation indicated that subsequent elective AAA repair was predicted by younger age at diagnosis and larger initial aneurysm size. As anticipated, patients who underwent surgery had more rapid aneurysm expansion (5.3 cm2/yr) compared with patients who did not undergo surgery (1.6 cm2/yr; p less than 0.05). This difference was caused by more rapid expansion during later follow-up intervals among patients selected for operation and was not predicted by the change in aneurysm size observed during initial ultrasonographic follow-up. Final aneurysm size was predicted by initial size, duration of follow-up, and both systolic and diastolic pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of glucose infusion on survival after acute mesenteric ischemia/reperfusion

Perfusion of ischemic tissue with glucose has been shown to be deleterious to heart, spinal cord, and kidney. Observations that glucagon improves survival after acute mesenteric ischemia, however, suggest that hyperglycemia may not be deleterious during bowel ischemia. This experiment examined the effect of glucose infusion on survival in an established rat model of acute mesenteric ischemia. The superior (cranial) mesenteric artery (SMA) was occluded for 85 min in 36 anesthetized Sprague-Dawley rats. Animals were randomized to receive 5% glucose in normal saline (n = 15; 16.5 mL/kg.min iv), normal saline alone (n = 13; 16.4 mL/kg.min iv), or no intravenous fluid (n = 8). Ninety-minute intravenous infusions were initiated 10 min after SMA occlusion. Survival to 48 h was 47% in glucose-saline-treated rats, 31% in saline-only-treated rats, and 12.5% in control rats. These results demonstrate no deleterious effect of glucose infusion on mortality after acute mesenteric ischemia in this model.

Effect of ampicillin-induced alterations in murine intestinal microbiota on the survival and competition of environmentally released pseudomonads

The environmental release of genetically altered microorganisms has prompted the investigation of their potential health effects by the employment of other-than-human models. Although direct health effects are addressed, this investigation examines primarily some potential indirect health effects associated with environmentally released microorganisms. Indirect effects examined include colonization of the gastrointestinal tract, competition with the resident microbiota, and translocation of the dosed microorganisms to other organs. Pseudomonads used in this study were isolated from a commercial product marketed for environmental PCB degradation. When mice were dosed by gavage with approximately 10(9) ampicillin-resistant pseudomonads, an increase in recovery from the intestinal tract, as compared to untreated animals, was observed 48 hr after dosing. Intestinal survival of Pseudomonas aeruginosa strain BC16 was enhanced 1000-fold and that of P. maltophilia strain BC6, 10-fold. Strains BC17 and BC18 were unaffected. Ampicillin treatment had a significant effect on the relative number of microbiota in the intestine, by selecting primarily for the facultative species. The lactose-fermenting enterobacteria, obligately anaerobic predominantly Gram-negative rods, and total aerobic and anaerobic populations were monitored in the presence and absence of the PCB-degrading pseudomonad. P. aeruginosa strain BC17 and P. maltophilia strain BC6 had a dose effect (p less than 0.05) on the total aerobic and anaerobic populations as well as the lactose-fermenting enterobacteria. These results are similar to those for the mouse isolate control, strain PAMG. P. aeruginosa strain BC18 had a dose effect (p less than 0.05) on the total anaerobic population, including the obligately anaerobic Gram-negative bacilli. No translocation of the dosed strains to the liver, spleen, or lung was observed 48 hr after dosing.

Limb salvage despite extensive tissue loss. Free tissue transfer combined with distal revascularization

Extensive lower-extremity tissue loss may preclude limb salvage despite successful arterial reconstruction. We attempted to avoid limb loss in such patients by combining arterial bypass with microvascular free tissue transfer. Fourteen patient (12 diabetic), 33 to 74 years of age, presented with extensive tissue loss in 15 lower extremities, exposing bone or tendon on the heel, ankle, lower part of the leg, or hindfoot. Mean ulcer size was 5 X 8 cm. Four patients had had previous contralateral below-knee amputations. Femorodistal (seven), popliteal-distal (three), or femoropopliteal (four) bypass, or tibial angioplasty (one), was performed to provide sufficient inflow for free tissue transfer. Serratus anterior, scapular, latissimus dorsi, rectus abdominis, gracilis, ulnar, or temporalis free flaps were used. One free flap failed due to venous thrombosis and was corrected with a second flap. Limb salvage was achieved in 14 (93%) of 15 limbs during a mean follow-up of 24 months. The single amputation occurred due to severe foot ischemia in a patient whose femorodistal bypass remained patent only to the viable free flap. The remaining 13 patients (14 limbs) became ambulatory, including those with free flaps to weight-bearing regions.

Tibial artery pseudoaneurysms: delayed complication of balloon catheter embolectomy

Although complications of balloon catheter embolectomy are infrequent, the injury potential of these catheters is well recognized. This article describes a case of multiple tibial artery pseudoaneurysms that appeared 4 years after embolectomy in a 42-year-old man with otherwise normal arteries. The patient was treated by internal aneurysmorrhaphy without sequelae. A literature review of balloon catheter injuries yielded 46 cases categorized as arterial disruption (29), intimal injury (12), or catheter malfunction (5). These resulted in hemorrhage (13 cases), arteriovenous fistula (12), pseudoaneurysm (four), thrombosis (three), dissection (five), accelerated atherosclerosis (four), and catheter fragment embolism (five). Of these complications, only 41% were recognized during the initial operation. Direct observation detected 32% of these, whereas 68% were shown only by completion arteriography. Complications recognized during initial operation were more frequently asymptomatic without further surgery (84%) than those detected postoperatively (30%, p less than 0.001). Completion arteriography detected 87% of balloon catheter complications compared with only 23% of complications recognized intraoperatively without arteriography (p less than 0.001). We conclude that delicate technique, completion arteriography, prompt surgical treatment, and extended follow-up are important components of balloon catheter embolectomy.

Cost-effectiveness of intra-arterial thrombolytic therapy

We reviewed the clinical course of 23 patients who received 24 intra-arterial infusions of either streptokinase or urokinase to treat 14 arteries and ten arterial grafts that were occluded due to primary thrombosis (22) or artery-artery embolism (two). Time from symptom onset to treatment was one to 28 days (mean, 11 days). Five infusions (21%) were completely successful since symptoms were eliminated without subsequent operation. Seven infusions (29%) were partially successful since thrombolysis aided, limited, or postponed subsequent surgery. Six infusions (25%) were failures since thrombolysis or clinical improvement did not occur and surgery was required. Six infusions (25%) were associated with thrombolytic complications that required urgent operation (less severe complications occurred in an additional 17% of cases [4/24]). Of the 19 patients without complete success after thrombolytic therapy, 16 underwent surgery during the same admission, two were not operable due to distal disease, and one declined operation. Of the 16 operations, 15 (94%) were successful in restoring graft or artery patency and achieving limb salvage, whereas one failed. In the 12 patients with failure or major complications of thrombolytic treatment, all had successful surgical outcome without morbidity. The actual mean cost of thrombolytic treatment was $8200 per patient and was comparable with the actual mean cost of subsequent surgical treatment in the 16 patients who required operation ($8900 per patient). The effective cost of thrombolytic and surgical treatment was calculated by dividing the actual costs by the proportion of successful cases. The effective cost of thrombolytic therapy per complete success was $39,200 and per complete or partial success was $16,500. This was significantly more than the effective cost of $9400 per complete success of surgical therapy.

Intraoperative single-dose radiotherapy. Observations on staging and interstitial treatment of unresectable liver metastases

Fourteen patients with a history of colonic cancer were evaluated for metastatic disease and were thought to have unresectable disease confined to the liver. Exploratory surgery revealed that two patients had extensive extrahepatic disease, and the procedure was terminated. In 12 patients, closed-end needles (diameter, 2.1 mm) were introduced into each nodule and connected to a 370-MBq (10-Ci) afterloading iridium source. Radiation doses were dependent on nodule size, providing minimum doses of 20 Gy (2000 rad) to the lesion's periphery with rapid radiation falloff avoiding toxic effects to adjacent normal tissue. The maximum number of nodules treated in one patient was 11. The largest nodule treated measured 9 x 6.5 x 6 cm. Cholecystectomy in four patients allowed precise implantation and obviated biliary fistula. Preoperative computed tomography underestimated the number of hepatic metastases in all cases but one, and treatment-induced computed tomographic alterations further limited its utility. Radiation treatment was well tolerated, and the median hospitalization was eight days. Of ten patients whose preoperative carcinoembryonic antigen values exceeded 10 ng/dL, the values in six patients decreased postoperatively.

Computer-assisted structure-activity relationships of nitrogenous cyclic compounds tested in salmonella assays for mutagenicity

Study of the relationship between mutagenicity and molecular structure for a data set of nitrogenous cyclic compounds is reported. A computerized SAR system (ADAPT) was utilized to classify a data set of 114 nitrogenous cyclic compounds with 19 molecular descriptors. All of the descriptors represented at least 10% of the compounds in the data sets. The average correct predictability of the data base was calculated to be 89% after evaluating 100 training/prediction subsets. The actual predictive ability of the discriminants generated by the ADAPT system was demonstrated by predicting the mutagenicity of structurally similar compounds not in the data set. Weight vectors generated in the pattern recognition programs were used to predict the bacterial mutagenicity of 10 compounds which were not included in the data set. All of the compounds were predicted correctly which was actually better than the 89% calculated by the system. This displayed the ability of the system of classify compounds as mutagenic or nonmutagenic by using molecular descriptors and to predict the biological activity of untested chemicals with a high degree of confidence. This paper presents the uses of this type of SAR approach in a research laboratory.