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Clinically significant arterial occlusive disease developed in 26 patients at between 5 months and 44 years (mean(s.d.) 10.7(12.0) years) following radiation therapy. Therapeutic radiation was associated with lesions of the carotid artery (nine patients), subclavian-axillary arteries (seven) and the abdominal aorta and its branches (10). Clinical presentations included transient ischemic attack, stroke, vertebrobasilar insufficiency, carotid bruit, upper- or lowerextremity ischemia and renovascular hypertension. Surgery for cerebrovascular insufficiency included carotid endarterectomy with vein patch, interposition grafting or subclavian-to-carotid bypass. Carotid or subclavian-to-axillary bypass was performed for upper-extremity ischemia. A combination of endarterectomy and Dacron or saphenous vein grafts was used for infrarenal reconstruction. Tunnels were placed orthotopically. Musculocutaneous flaps assisted in healing selected wounds. Ureteral catheters were useful adjuncts in abdominal vascular reconstructions. There were no operative deaths, strokes or amputations. One patient had recurrent transient ischemic attacks following subclavian-to-carotid bypass. The mean(s.d.) postoperative follow-up was 48.1(39.6) months. Patients presenting with end-organ ischemia following radiation therapy can be managed successfully with aggressive surgical revascularization using a broad spectrum of reconstructive techniques.

Purpose: Autogenous vein bypass grafts to infrapopliteal outflow sites have patency and limb salvage rates significantly superior to those obtained with prosthetic grafts. However, when infrageniculate bypass is required for limb-threatening ischemia in the patient lacking suitable autogenous veins, nonautogenous reconstruction or primary amputation are the only other alternatives. Methods: During a 2-year period we implanted 25 cryopreserved allograft saphenous vein bypass grafts in 24 patients (median age 76 years) with tissue necrosis (20 patients), rest pain (4 patients), or acute ischemia (1 patient); 16 patients were men and 8 were women. As many as six previous revascularizations were performed in 79%; two grafts extended to the infrageniculate popliteal artery; 23 grafts extended to a paramalleolar vessel. Results: Secondary patency at 1 month was 87%, but only 36% at 1 year. Use of warfarin (Coumadin) failed to improve the patency rate (five of nine occlusions treated with Coumadin versus eight of 16 not treated with Coumadin). Only eight of 24 patients are alive with open grafts; nine patients have died. Conclusions: Unheralded occlusions more typical of prosthetic graft failure tempered the initial enthusiasm and effectiveness of vein allografts. All autogenous options must be exhausted to complete distal, secondary revascularization before resorting to nonautogenous conduits. Use of allograft veins must be viewed with continued skepticism. (J VASC SURG 1993;18:553-60.)

As vascular surgeons, we performed 376 percutaneous transluminal angioplasties as follows: aorta and iliac arteries (148), infrainguinal arteries (191), and bypass grafts (21). Sixteen procedures were attempted but not completed. Neodymium-yttrium-aluminum-garnet laser thermoprobe was successfully used prior to balloon dilatations in 49 procedures. In contrast to our experience with operative intervention, percutaneous transluminal angioplasty was performed more frequently for claudication (75%), nondiabetics (72%), and women (45%). Median age was 71 years. Percutaneous transluminal angioplasty either preceded or followed proximal or distal open reconstruction in 58 extremities. Primary patency rates for iliac percutaneous transluminal angioplasties were: 94% at one month, 93% at six months, and 88% at one year. For infrainguinal percutaneous transluminal angioplasties they were 95%, 82%, and 70% at 1, 6, and 12 months, respectively. Repeat percutaneous transluminal angioplasty increased the one-year patency rates to 92% and 86% for iliac and infrainguinal percutaneous transluminal angioplasties, respectively. Preliminary data indicate that the six-month secondary patency rates were 82% for laser-assisted percutaneous transluminal angioplasty and 65% for percutaneous transluminal angioplasty of distal bypass grafts. The implementation of balloon angioplasty was facilitated by our 21 years of experience with arteriography. Percutaneous transluminal angioplasty has become a valuable adjunct to the practice of vascular surgery by expanding the therapeutic options for managing peripheral vascular occlusive disease.

Although balloon angioplasty for the management of failing bypass grafts has been well documented, little mention has been made of its use in treating the occlusive lesion within the native artery after a failed bypass graft. We report our experience with five patients in whom successful balloon angioplasty was carried out subsequent to failure of a femoral popliteal bypass graft. Increasingly aggressive percutaneous therapy of arterial occlusive disease may now be expanded to include a unique group of patients with chronically failed bypass grafts and occlusive disease within the native artery conducive to percutaneous transluminal angioplasty. This group of patients would previously have been relegated to repeat bypass grafts with its inherently inferior patency and recognized added technical demands. Percutaneous balloon angioplasty appears to be a plausible alternative in selected cases for repeat lower extremity revascularization.

A technique for closed reduction and percutaneous screw fixation of fractures of the iliac wing and fracture-dislocations of the sacro-iliac joint is presented. Twenty-seven pelvic fractures were treated with attempted closed reduction followed by percutaneous screw fixation. Closed reduction failed in two patients. In the other twenty-five, closed reduction to within one centimeter of residual displacement was obtained, and was followed by stabilization with percutaneously placed cannulated screws. Complications included dislodgment of a screw from the superior pubic ramus in one patient, and partial cut-out of a screw along the inner cortex of the iliac wing in another. Two patients were lost to follow-up before fracture union occurred. The remaining twenty-three patients were followed-up for an average of twenty-seven months (range, 18-48 months). All of the fractures healed in the twenty-three patients who were not lost to follow-up. All but two of the patients who were working before injury returned to work. All but one of the patients was satisfied with the outcome of their pelvic fracture treatment. Closed reduction and percutaneous screw fixation of fractures of the posterior portion of the iliac wing yields acceptable reductions, with minimal blood loss and limited damage to the surrounding soft tissues.

Acoustic Emission techniques have been used in a variety of applications in industrial plant, and the special techniques developed by Metacoustics can provide real time defect location; identify processes and procedures damaging pressurised equipment; provide a structural integrity evaluation, and after a number of tests and analysis operations provide an estimate of remnant life of the structure monitored.

Purpose: Percutaneous access to the arterial system for endovascular procedures is usually achieved through the femoral arteries. When femoral access is precluded, the axillary or brachial arteries serve as alternatives. Complications associated with the use of the latter arteries have led us to develop subclavian arterial catheterization. Methods and Results: From 1978 to 1993, 569 patients underwent angiography via the subclavian artery (>99% left subclavian artery); 134 were studies of the aortic arch and brachiocephalic vessels; 435 studies involved the descending and abdominal aorta and its branches and runoff. Coronary arteriography was also feasible. Since 1986, 44 patients have undergone endovascular procedures: 33 percutaneous transluminal angioplasties of the visceral, iliac, femoral, and popliteal arteries and 11 thrombolytic procedures of aortofemoral graft limbs ( n = 3) and femoral distal bypasses ( n = 8) were performed. Complications (1.2%) included partial pneumothorax ( n = 2), hemorrhage requiring operative control ( n = 2), causalgia ( n = 1) and embolization ( n = 2). Conclusions: Whenever percutaneous femoral catheterization cannot be achieved or an alternate access point is indicated, we select the subclavian approach as an alternative to axillary, brachial or translumbar access. It is safe, expeditious, and versatile for virtually all types of systemic and cardiac catheterization; it is also applicable to thrombolysis and balloon angioplasty. (J VASC SURG 1994;20:566-76.)

The current clinical application and technique of percutaneous transluminal balloon angioplasty (PTA) are the culmination of work which began in 1964, when Dotter and Jenkins dilated vascular lesions using a rigid coaxial catheter system. Catheters were later modified into tapered tubes by Van Andel and Staple. A balloon catheter was introduced by Porstmann in 1973, and Gruntzig developed the double-lumen, non-elastomeric, polyvinyl balloon catheter in 1974. The Gruntzig device permitted catheter placement over a guidewire and controlled balloon inflation, and it formed the basis for modern PTA techniques.

This article recounts the author’s experience using wind chimes to teach the scientific method including significant figures, experimental error, types of variation, peer review of results, seeking empirical relationships within data, and testing the relations found.

This article recounts the author’s experience building a physics site on the World Wide Web and using the site with a high school pnysics class.

The historical and current reasons for quantifying opera house acoustics (the why?) are reviewed. The emerging shift from quantitiative assessment (by measurement) to qualitative assessment (by auralization) is discussed. The key characteristics of the acoustics of opera houses (the what?) are then considered. Assessment of a theatre with an audience present is suggested to be more important than unoccupied measurements. This has implications for the development of assessment methods. The suitability of classical room acoustics parameters—mostly derived from concert hall studies—is debated (the how?). Possible new assessment techniques are emerging. Characteristics not addressed by the classical parameters include the early (ensemble) and late (room) support provided to the singers and the onset threshold of image shifting of the sound of instruments within the orchestra pit. The assessment of loudness balance between the stage and the pit requires refinement and development. A difficulty with the assessm...

We measured ankle/arm pressure indexes and blood flow rates before and after performing percutaneous transluminal angioplasty in 36 extremities. Flow rates through the leg were determined with a magnetic resonance blood flow scanner. All patients had claudication; one had gangrene, another had an ulcer, and two complained of rest pain. The median age was 65 years, and 72% were men. There were 25 dilations of the iliac artery, 12 of the superficial femoral artery, and eight of the popliteal arteries; nine patients had two arterial segments dilated. Nineteen legs had ankle/arm pressure indexes before percutaneous transluminal angioplasty of less than 0.80 (range 0.51 to 0.75); their flow rates averaged 40 ± 20 (SD) ml/min. After percutaneous transluminal angioplasty flow and pressure increased significantly in 14 of these 19 legs, and three had no hemodynamic improvement; in one leg only pressure and in another only flow increased significantly. The remaining 17 extremities had ankle/arm pressure indexes before percutaneous transluminal angioplasty ranging from 0.81 to 1.09; their flow rates averaged 53 ± 27 (SD) ml/min. Abnormal flow rates were detected in 15 of these 17 extremities. With near-normal ankle/arm pressure indexes no significant increase in pressure was anticipated. Flow rates augmented to 75 ± 28 (SD) ml/min after percutaneous transluminal angioplasty; a significant increase in flow was noted in 12 legs (71%). For patients with ankle/arm indexes before percutaneous transluminal angioplasty. of less than 0.80, either pressure or flow measurements should corroborate the benefits of the operation, whereas if the ankle arm index is greater than 0.80, flow measurements are most likely to substantiate changes in peripheral hemodynamics. (J Vasc Surg 1989;10:338–42.)

The results of 160 infrainguinal bypasses with arm vein grafts were analyzed. Seventy-three arteriograms were reviewed to identify early and late graft defects; arteriographic findings paralleled those described for saphenous vein grafts. Intimal fibrosis during the first postoperative year, observed in 16 grafts, was the most common defect. Aneurysmosis and elongation were rare, resulting in two graft replacements. Patency and limb salvage rates were calculated for 88 single-length femorodistal bypass grafts; the other 72 were inflow (eight) or outflow (22) jump grafts, sequential (eight) and composite autogenous vein grafts (34). The primary and secondary patency rates for single-length grafts were 74% and 80% at 1 year and 51% and 57% at 5 years, respectively. The limb salvage rate at 5 years was 82%. The survival rate for all patients was 44% at 5 years. These findings reconfirm our use of arm veins as bypass grafts when the saphenous vein is unavailable. (J VASC SURG 1986;4:416-27.)

A case of acute aortic occlusion caused by embolization of malignant melanoma tumor fragments is presented. Transfemoral catheter embolectomy restored normal lower extremity circulation. Noncardiac tumor emboli, although rare, originate either from primary pulmonary malignancies or nonpulmonary malignancies with pulmonary metastases and pulmonary vein invasion. Tumor embolization should be considered a possible source of peripheral arterial emboli when there is no other obvious source, such as the fibrillating or infarcted heart. In such cases, early surgical intervention should be considered in preference to therapy with heparin or streptokinase.

Nonthrombotic iliofemoral venous obstruction, masquerading as deep vein thrombosis, was diagnosed in four patients. In each instance the patient was hospitalized and intravenous heparin therapy was started. Phlebography demonstrated venous outflow obstruction without thrombosis; subsequent CT scanning revealed an obstructing lesion in each case. At surgical exploration, (1) endoaneurysmorrhaphy of a hypogastric artery aneurysm decompressed an obstructed right iliac vein; (2) a primary iliac vein leiomyosarcoma was extirpated; (3) a synovial cyst arising from the right hip joint, which obstructed the femoral vein, was excised; and, (4) a postherniorrhaphy inflammatory mass obstructing the left iliofemoral vein junction was confirmed with biopsy results. Improved diagnostic accuracy with its attendant specific therapy is achieved in suspected cases of iliofemoral vein thrombosis if, in addition to noninvasive venous studies or phlebography, CT scanning of the abdomen and pelvis is performed.

Preoperative noninvasive imaging of the veins of the upper extremities has been included in the protocol to select an autogenous vein for a distal bypass in the lower extremity. Arm veins are sought as bypass grafts when the saphenous vein is absent or not usable. Duplex ultrasound provided images of the cephalic and basilic veins in 10 patients in whom visual inspection failed to reveal usable grafts. All arm veins implanted were at least 2 mm (range 2 to 6 mm) in internal diameter determined by ultrasound and were, on the average, 2 mm larger when unroofed. This noninvasive technique has decreased the number of fruitless surgical explorations to obtain a suitable arm vein and has increased the use of arm veins by revealing veins previously not anticipated by physical examination, which virtually eliminated the use of nonautogenous conduits in our practice.

In many instances digitised data are received from a process being monitored where some of the data values are suspect and therefore cannot be included in any analysis. Often an important parameter which is to be calculated is the power spectral density (PSD) and it is shown how this can still be computed for data sequences where values are either missing or suspect using straightforward techniques and not employing sophisticated interpolation procedures. The two procedures are the discrete Fourier transform (DFT) and the maximum entropy spectral analysis (MESA) approach. These two procedures were applied to data originating from white noise excitation of resonant systems which had data missing. The DFT technique predicted correctly the positions of the peaks in the PSD but the PSD was not a smooth curve due to the use of a small sample length, and the noise background increased as the number of missing values increased. The MESA technique gave smoother estimates of the PSD. However, as the number of missing values increased it started to give incorrect values for the spectral heights and their frequencies. The MESA technique is based on an autoregressive model which is fitted to the data, and the determination of the number of coefficients (model order) presents some problems particularly since there is an upper limit on this number due to the cumulative effect of missing values in the computational procedures.

Two hundred forty-three bypasses to paramalleolar arteries were performed in 224 extremities of 208 patients since 1971; 166 were implanted in men (68%) and 77 in women (32%). The median age was 73 years. Gangrene (61%), nonhealing ulcer (15%), rest pain (22%), and trauma (2%) were the indications for bypass. Usual risk factors were noted: diabetes (65%), smoking (51%), heart disease (46%), and hypertension (45%). The extent of occlusive disease dictated three graft configurations: long grafts originating in arteries proximal to the adductor tendon (n = 111), short grafts originating at or below the popliteal artery (n = 88), and jump grafts originating near the distal end of a previous femorodistal bypass (n = 44). The association between diabetes (incidence 80%) and gangrene (75%) in patients with short grafts was statistically significant (p less than 0.01). The 2-year secondary patency rate of long in situ grafts was 92% compared with 72% for other autogenous vein long grafts. The limb salvage rate for all autogenous vein long grafts was 90% at 3 years. The secondary patency rate at 3 years for short grafts was 81% and the limb salvage rate was 80%. There were four amputations with patent grafts. Primary and secondary patency rates of jump grafts were similar (53%), whereas the limb salvage rate was 89% at 2 years. Patency and limb salvage rates of rarely employed nonautogenous conduits were less than 35% at 1 year (long grafts). Bypass grafts to the ankle and foot are effective and durable and should be performed with autogenous vein.

A method is described for analyzing the projected focal spot of a light beam spread by propagation through atmospheric turbulence. The degradation in the spot caused by the wander of its centroid is analyzed separately from the average spread of the intensity distribution about the centroid. The technique presented utilizes a unique analog circuit for measuring the time‐centroid of the pulse which represents a one‐dimensional scan of the light spot.

We placed 20 bypass grafts to the lateral plantar artery in 18 extremities to salvage feet with wet (12) or dry (six) gangrene; 15 grafts were implanted in men (75%), and five were implanted in women (25%). The median age was 65 years. All except two patients had diabetes; eight were treated with insulin. One patient had Buerger's disease, and another had vasculitis with chronic lymphocytic leukemia. History of smoking (65%), hypertension (53%), heart disease (71%), and osteomyelitis in the foot (35%), were noted. Cultures were positive in 15 gangrenous feet, 11 with gram-negative bacilli. Four long femoroplantar bypasses were placed. Ten short grafts were placed from the popliteal artery, and six jump grafts were placed distal to a femoropopliteal or tibial bypass. Hospital stay ranged from 8 to 38 days (median 16 days), and there were two in-hospital deaths. Transmetatarsal or button toe amputations were performed in nine feet. There were two below-knee amputations, one with a patent graft, for a foot salvage rate of 89% at 2 months. In four instances the gangrenous ulcers took longer than 6 months to heal; all other wounds healed within 6 months. The primary and secondary patency rates were 85% at 1 month, and 73% at 3 months and thereafter. Four of five graft failures occurred in the two legs with repeat bypass graftings. All patients with successful revascularization are able to walk, and seven returned to work full time.

The Washington, D.C. transportation-visitor center will provide a place for the orientation and direction of visitors to the Nation’s Capital as well as a consolidation of terminals for intercity and local transportation systems. Studies were made of existing travel and relationships between modes so that models could be developed for forecasting future demands and interfaces. All forms of line haul transportation such as railroad, bus and air, as well as local modes such as bus, rail rapid transit, helicopter, taxi and auto were taken into account. Findings were applied to physical planning for an area surrounding Union Station, resulting in a proposed plan and program for the consolidation of transportation terminals, a visitor center and adjunct facilities. While the studies are applied to Washington, D.C., the methodology used is intended to be a prototype for use in many applications.

It is shown that for particles tripped in the geomagnetic field the first-order effect of nonconservation of magnetic moment is to raise the mirror points by an amount depending on the position of the unperturbed mirror point. It is shown that the net change in the magnetic moment over a complete north- south mirror oscillation is zero, and that the effect is therefore a static deformation of the orbit (i.e., there is not a progressive raising of the mirror points). An expression is derived for the angular derivative of the magnetic moment, and from this an expression is obtained for the increase in mirroring altitude. It is seen that the effect is most significant for high-energy protons trapped on high magnetic shells and is essentially negligible for electrons. (auth)

Publisher Summary This chapter discusses the use of cephalic vein as a conduit. The choice of cephalic vein as an arterial conduit requires the surgeon to consider the relative merits and shortcomings of all currently employed grafts for leg revascularization. Arm veins are evaluated preoperatively and intraoperatively. The cephalic and basilic veins are assessed, preferably in a warm room, by inspection and palpation, employing tourniquets, exercise, and dependency. Special attention is directed to the antecubital fossa as variations in venous anatomy are sometimes encountered. Inexact preoperative assessment may result from hair, obesity, or tattoos. The median antecubital vein receives a deep muscular branch and the forearm branch of the basilic veinand, thereafter,continues as the basilic vein to the axilla. In the forearm, the basilic vein diameter is smaller and more variable than the forearm portion of the cephalic vein. Moreover, it lies posteriorly, its excision is awkward, and it is not a useful saphenous vein substitute. Males and females appear to have equally usable cephalic veins. Cephalic vein diameter, generally 5-6 mm distally and 6-8 mm proximally, tends to be more uniform than that of the saphenous vein.

• When a suitable single length of saphenous or arm vein is unavailable, the elderly patient with a profoundly ischemic extremity, poor runoff, and a distal outflow vessel frequently undergoes amputation. Rather than performing primary amputation or resorting to nonautogenous conduits, we used 21 different combinations of available vein segments of ipsilateral or contralateral greater saphenous, lesser saphenous, cephalic, and basilic veins as composite autogenous bypass grafts. Fifty-four extremities, of which 21 (39%) had one or more failed previous bypasses, were revascularized. Tissue necrosis necessitated operation in 74% (40 instances) and rest pain in 19% (ten instances). All grafts extended below the knee, 22% (12 grafts) to the infrageniculate popliteal artery, 78% (42 grafts) to an infrapopliteal runoff vessel, and 28% (15 grafts) to the ankle or foot. The patency rate at one month was 81%. Thrombectomy alone or with local graft repair increased the one-month patency rate to 96%. At one year, the patency and limb salvage rates were 74% and 82%, respectively. ( Arch Surg 1986;121:1128-1132)

Successful long-term limb salvage using cephalic vein bypass grafts was attained in 70 limbs of 67 patients over the past 11 years. The saphenous vein was absent in 76% and inadequate in 24% of the cases. Revascularization for limb salvage was carried out in 83%. Ninety per cent of the grafts were extended to the infrageniculate level while 56% were to a tibial vessel. Patency rates at 1, 3, and 5 years were 85%, 72%, and 68%, respectively. Limb salvage rate was 85% at 5 years and thereafter. There were no operative deaths or upper extremity morbidity. The 5-year survival rate was 50%. The results obtained with cephalic vein were comparable to those reported using saphenous vein but superior to those reported for nonautogenous bypass grafts.

This study is an attempt to explore further the relative roles of virus particle and hosttissue antigens in the genesis of local and systemic reactions to subsequent vaccine challenge. Immunization with inactivated measles vaccine may simultaneously sensitize to its viral component, as well as to nonviral host material in the vaccine. Dermal hypersensitivity following natural measles, accelerated appearance of fever and rash in prior recipients of inactivated measles vaccine when challenged with live measles vaccine, and the unusual clinical picture observed in children previously given inactivated vaccine when infected with wild measles virus bespeak primarily of viral sensitization. On the other hand, delayed dermal and local reactions to live mumps vaccine in prior recipients of inactivated measles vaccine, both of which were grown in chick embryo fibroblasts, appear to represent host tissue sensitization. With the introduction of newer myxovirus vaccines, further definition of the mechanism involved in such reactions may assume practical significance.

• Subclavian and axillary artery occlusive disease resulted in sufficient upper extremity symptoms to necessitate 30 vascular reconstructions in 28 patients over the past ten years. Female patients predominated, with a ratio of 2.5:1. The average age of the patients was 61 years. The incidence of diabetes mellitus was low (7%). Sixteen of 18 proximal subclavian lesions were on the left side, while more distal lesions were equally distributed on the left and right. Extrathoracic bypasses were used in all cases. Dacron grafts were used in 16 of 17 carotid-subclavian bypasses. Autogenous vein grafts were used in 11 of 13 bypasses to the axillary or brachial artery. Concomitant cervicodorsal sympathectomy was done in only four patients. The in-hospital graft patency rate was 93% and the long-term graft patency rate at one year and beyond was 88%. (Arch Surg1984;119:1277-1282)