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Biomedical subjects

W H Baker

Publications and source records attributed to W H Baker.

At least 19 recordsLinked to original sources
PubMed2003

Improved venous return by elliptical, sequential and seamless air-cell compression.

AIM: The risk of deep vein thrombosis (DVT) in the peri-operative period is significant, but can be reduced with the use of mechanical intermittent pneumatic compression (IPC). These devices have reached widespread use in hospitals and have been found to be effective prophylactic measures against DVT. This study evaluates the latest design features of one particular IPC device in comparison to current models. METHODS: Duplex ultrasound scanning was performed on 40 lower extremities of 20 healthy volunteers before and during the application of the IPC device (VenaFlow System, Aircas, NJ, USA. Two hemodynamic parameters were measured, acceleration time from spontaneous baseline venous flow and peak vein velocity. All measurements were obtained by scanning proximal to the saphenofemoral junction in the common femoral vein in both extremities for each subject. Data were obtained from 3 compression cycles and averaged for each extremity. Results were compared with a recent prospective study form our center using a slow-filling and a rapid-filling sequential IPC devices. RESULTS: The medians for spontaneous average peak velocities at rest of the right and left lower extremities were 26 cm/s and 24.1 cm/s. The median augmented peak velocities during the compression cycle of the device in the right and left side were 79.6 cm/s and 79.0 cm/s. This represented a 306.2% increase in average peak velocity on the right side and a 327.8% increase on the left side. The median acceleration time was 305 ms +/- 40 in the left and 310 ms +/- 50 in the right limb. There was no statistically significant difference in the spontaneous and augmented velocities between the right and left lower extremities in each subject. In comparison to existing slow- and rapid-filling IPC devices the VenaFlow System had superior peak velocities and shorter acceleration times. CONCLUSION: The use of elliptical, sequential and rapid-filling compression of the leg with overlapping air-cells produces significant hemodynamic changes in the common femoral vein, which are superior to other sequential slow- or rapid-filling IPC devices. Randomized studies should be performed to determine the efficacy of this new device in DVT prevention.

Adult↗
PubMed2002

Early thrombus remodelling of isolated calf deep vein thrombosis.

OBJECTIVE: this prospective study was designed to evaluate the evolution of thrombus propagation and lysis in relation to patterns and distribution of isolated calf DVT. METHODS: fifty-two limbs in 48 patients mean age 59+/-15, range 24-78 years, with isolated calf DVT that had at least one exam within 10 days of DVT detection were included in the study. Patients with a documented episode of prior DVT or evidence of post-thrombotic changes during the initial ultrasound exam were excluded. The initial thrombus length, patterns and location of the thrombi were recorded. On follow-up the propagation and lysis patterns of the clot were studied. RESULTS: remodelling of the thrombus, excluding echotexture and vein diameter changes on ultrasound, occurred in 23 limbs, (44%). Ascending propagation only was seen in seven limbs (13%) descending propagation only in two (4%) and in both directions in five (10%). Propagation at least to popliteal vein was detected in seven limbs (13%). Thrombus developed or extended to initially uninvolved veins in six limbs (12%). Pulmonary embolism developed only in one patient (2%; 95% CI: 0-11%). The site and the size of thrombus or the number of veins involved in the baseline exam did not correlate with the remodeling of thrombus. Soleal and gastrocnemial veins were comparable with the posterior tibial and peroneal veins in terms of thrombus propagation and lysis. CONCLUSIONS: early thrombus remodelling occurs in 44% of limbs with isolated calf DVT. This includes ascending and descending thrombus propagation and lysis. Thrombus development or propagation to initially uninvolved calf veins is found in 12%. Thrombus remodelling does not appear to be related to size, site and patterns of thrombosis.

Adult↗
PubMed2001

Ureteral injury during aortic aneurysm repair by the retroperitoneal approach.

Three ureteral injuries (two proximal, one middle) associated with retroperitoneal repair of aortic abdominal aneurysms are reported. The authors believe these represent traction injuries that are related to the use of stationary retractors and suggest that complete anterior mobilization of the left kidney from its posterior fossa will decrease the odds of such an injury.

Aged↗
PubMed2001

Timing of postcarotid complications: a guide to safe discharge planning.

OBJECTIVES: Currently, our standard of practice is that patients undergoing carotid endarterectomy (CEA) may be safely discharged on the first postoperative day. Because many patients do not appear to require overnight observation, we wanted to determine the safety and feasibility of same-evening discharge by establishing the timing of postoperative complications, which may potentially require operative intervention. METHODS: A total of 835 consecutive patients undergoing CEA were retrospectively reviewed. Sixty-two patients had a postoperative wound hematoma or neurologic deficit (ND) (transient ischemic attack or stroke) within 24 hours of their operation, complications potentially requiring a second operation. Excluded were 64 patients not eligible for same-day discharge because of other reasons (eg, heparinization, CEA with coronary artery bypass grafting). RESULTS: Sixty-two patients (8.0%) had ND (26 [3.4%]) or neck hematoma (NH) (36 [4.7%]) within 24 hours of their CEA. Nineteen (73%) of the NDs were diagnosed in the operating room or recovery room, 5 (19%) within 8 hours of the operation, and 2 (7.7%) after 8 hours but in less than 24 hours. Of the NHs, 23 (66%) were diagnosed in the recovery room, 11 (31%) within 8 hours, and 1 (2.7%) after 8 hours. Of the outliers, one patient experienced a blowout of the vein graft occurring on postoperative day 1, one patient had a delayed ipsilateral stroke, and one had a vertebrobasilar stroke. Overall, only three of 773 (0.4%) patients undergoing CEA had a complication occurring more than 8 hours after operation. CONCLUSION: NDs and NHs in post-CEA patients occurred within 8 hours of operation in 95% of those patients experiencing these complications or 99.6% of all CEA patients. These data indicate that same-evening discharge may be safely performed without increasing the adverse effects of stroke or hematoma. This plan has cautiously been initiated at this institution.

Endarterectomy, Carotid↗
PubMed2001

Nonsaphenous superficial vein reflux.

BACKGROUND: Information on nonsaphenous superficial venous reflux is lacking. This study was designed to determine the prevalence of reflux in nonsaphenous veins, their association and correlation with risk factors, and signs and symptoms of chronic venous disease (CVD). METHODS: Information on 835 limbs in patients with signs and symptoms of CVD were prospectively entered into a customized database. These patients had been referred from the venous clinic to the vascular laboratory for color-flow duplex scanning evaluation of the lower-limb veins. All patients were examined for reflux in the standing and sitting positions. Nonsaphenous reflux was defined as that in superficial veins that are not part of the greater or lesser saphenous systems. Particular attention was paid to the patterns of reflux and anatomy of the nonsaphenous veins from the proximal to the distal ends, including their connections with the saphenous and deep veins. RESULTS: Nonsaphenous venous reflux was found in 84 limbs (10%) of 72 patients, 67 of whom were women. The mean number of pregnancies in these patients was higher than that of 100 randomly selected women with saphenous reflux (3.2 vs 2.2). According to CEAP classification, 90% of the limbs were in CVD classes 1 through 3 and only 10% had skin damage (classes 4-6). Symptoms were present in 67 limbs (80%). Forty-two limbs (50%) had reflux in tributaries of lateral, posterior, and medial thigh. These veins were connected with perforators uniting with the deep femoral, femoral, and muscular veins of the thigh in 36 limbs. Reflux in these perforators was detected in 19 limbs. Reflux arising from the pelvic veins was found in 29 limbs (34%), 18 of which were from vulvar veins medial to saphenofemoral junction and 11 of which were from veins in the gluteal area. Incompetent veins from the sciatic nerve were found in nine limbs (10%). Reflux in the vein of the popliteal fossa was found in seven limbs (8%). Reflux in knee tributaries was detected in three limbs (4%), two of which were connected with posterolateral knee perforators and one with the posterior tibial nerve veins. CONCLUSIONS: The prevalence of nonsaphenous reflux in our practice was 10%. The vast majority of these patients (93%) were women with a mean of 3.2 pregnancies. Ninety percent of these limbs have signs and symptoms assigned to CVD classes 1 to 3. These data may simply reflect the referral pattern, but also a possible association with female sex and number of pregnancies. The unusual anatomy of these veins stresses the importance of color-flow duplex scanning before surgery.

Chronic Disease↗
PubMed2001

Toxicity of 2,6-Di-tert-butyl-4-Nitrophenol (DBNP).

U.S. Navy submarines reported a yellowing of metal surfaces on their internal surfaces. The yellowing was initially identified on the painted steel bulkheads but further examination indicated that it was not limited to steel surfaces and included bedding, thread tape, Formica, plastisol covered hand-wheels, and aluminum lockers. Crew members also reported to the medical department that their skin turned yellow when they came in contact with these contaminated surfaces and requested information on the effects of exposure. Studies conducted by General Dynamics' Electric Boat Division (EBD) determined that the agent was 2,6-Di-tertbutyl-4-Nitrophenol (DBNP). 2,6-Di-butylphenol (DBP) is an antioxidant additive used in lubricating oils and hydraulic fluids. In the enclosed atmosphere of a submarine, the oil mist could be spread throughout the boat by venting the lube oil to the atmosphere. Submarines use electrostatic precipitators (ESP) to clean the air of particulate materials. During passage through the ESP, oil mist containing DBP is nitrated to DBNP, which is then moved throughout the boat in the ventilation system. Analysis of the EBD data indicated 24-hour exposure concentrations to be in the range of <3.0 to 122 ppb in the laboratory and submarine settings. Submarine crews may be exposed to these concentrations for as many as 24 hours/ day for 90 days during underway periods. Toxicity studies regarding the oral and dermal uptake of DBNP were conducted. From the literature the lethal dose to 50 percent of the population (LD50) of DBNP (rat) was reported by Vesselinovitch et al. in 1961 to be 500 mg/kg. Our studies indicated that the LD50 is in the range of 80 mg/kg in the rat. Our work also includes dermal absorption studies, which indicated that DBNP is not well absorbed through intact skin. Within this study, no no-observable adverse effect level (NOAEL) or lowest observable adverse effect level (LOAEL) was identified. Calculation of a reference dose was completed using standard methods based on the LD50 as a numerator with several uncertainty and modifying factors. EBD's determination of airborne concentrations aboard submarines fall in the range of these anticipated allowable concentrations and could indicate significant chronic exposures. No adverse effects from DBNP exposures have been reported to date.

Animals↗
PubMed2001

Nelfinavir desensitization.

OBJECTIVE: To report the first case of nelfinavir desensitization in an HIV patient who was intolerant to protease inhibitors. CASE SUMMARY: A 43-year-old HIV-positive white man was treated with several protease inhibitors. The patient developed rashes in response to all protease inhibitors. His viral load was controlled only in the presence of a protease inhibitor. The patient tolerated nelfinavir longer than the other agents; therefore, the decision was made to attempt to desensitize him to nelfinavir. A six-hour inpatient protocol was used, and he tolerated the procedure without event. His disease is now well managed without recurrence of the rash. DISCUSSION: The use of protease inhibitors has had a major impact on the morbidity and mortality of HIV-infected patients, Despite their benefits, this class of drugs is not without adverse effects. Allergic reactions in the form of rashes may develop, which can severely limit treatment options in HIV patients. We report the first case of rapid desensitization of nelfinavir in a patient who developed rashes to several protease inhibitors. CONCLUSIONS: Intolerance to protease inhibitors due to rash is a well-documented phenomenon. In HIV patients, this can limit treatment options severely. This case demonstrates how desensitization to nefinavir can be performed successfully.

Adult↗
PubMed2001

Decreased recurrent carotid stenosis by routine patching and intraoperative scanning.

Our objective was to review the results of carotid endarterectomies (CEAs) with Dacron patch angioplasty and intraoperative color-flow duplex scanning (CFS). In a 3-year period, patients who underwent CEA with Dacron patch angioplasty and intraoperative CFS were studied. We excluded patients who had primary closure, vein patch, and redo endarterectomy. Serial CFS was obtained first in the early postoperative period (one day to 3 weeks), then at 6 months, and then yearly. Intraoperative CFS abnormalities were classified as major, requiring immediate revision, or minor, which were observed. The diagnosis of recurrent stenosis by US was based on the detection of an increased peak systolic frequency (>8000 MHz) or velocity (>250 cm/second) in the internal carotid artery. There were 212 CEAs performed in 200 patients (128 men and 84 women) included in this study. Three patients (1.4%) awoke with a stroke, two (0.94%) had transient ischemic attacks, and three (1.4%) developed transient hypoglossal nerve paresis. Intraoperative CFS showed a major defect that required an immediate revision in six patients (2.8%). Minor abnormalities were detected in another 41 patients (19.3%), but no revision was necessary. In follow-up three patients were identified with a severe recurrent carotid stenosis (>80%) and they underwent redo CEA. This rate of recurrence (1.4%) is significantly lower than the rate we had previously reported in a larger study (82 of 1209, 6.8%; P = 0.003). We conclude that the combined use of Dacron patch angioplasty and intraoperative CFS after CEA is associated with a low perioperative morbidity and a low incidence of recurrent stenosis in the first 2 years after operation.

Aged↗
PubMed2000

Expanded indications for ultrasound-guided thrombin injection of pseudoaneurysms.

PURPOSE: We previously reported preliminary data on a new procedure that we developed for the treatment of femoral pseudoaneurysms after catheterization. This study presents our current results of percutaneous ultrasound-guided thrombin injection for treating pseudoaneurysms that arise from various locations and causes. METHODS: Between February 1996 and May 1999, we performed thrombin injection of 83 pseudoaneurysms in 82 patients. There were 74 femoral pseudoaneurysms: 60 from cardiac catheterization (36 interventional), seven from peripheral arteriography (four interventional), five from intra-aortic balloon pumps, and two from dialysis catheters. There were nine other pseudoaneurysms: five brachial (two cardiac catheterization, two gunshot wounds, one after removal of an infected arteriovenous graft), one subclavian (central venous catheter insertion), one radial (arterial line), and one distal superficial femoral and one posterior tibial (both after blunt trauma). Twenty-nine pseudo-aneurysms were injected while on therapeutic anticoagulation. Patients underwent repeat ultrasound examination within 5 days and after 4 weeks. RESULTS: Eighty-two of 83 pseudoaneurysms had initial successful treatment by this technique, including 28 of 29 in patients who were undergoing anticoagulation therapy. The only complication was thrombosis of a distal brachial artery, which resolved spontaneously. There were early recurrences in seven patients: four patients underwent successful reinjection; reinjection failed in two patients, who underwent surgical repair; and one patient had spontaneous thrombosis on follow-up. After 4 weeks, ultrasound examinations were completely normal or showed some residual hematoma, and there were no recurrent pseudoaneurysms. CONCLUSION: Ultrasound-guided thrombin injection of pseudoaneurysms has excellent results, which support its widespread use as the primary treatment for this common problem.

Adult↗
PubMed2000

The reduction of the allogenic transfusion requirement in aortic surgery with a hemoglobin-based solution.

OBJECTIVE: Because of allogenic red blood cell (RBC) availability and infection problems, novel alternatives, including hemoglobin-based oxygen-carrying solutions (HBOC), are being explored to minimize the perioperative requirement of RBC transfusions. This study evaluated HBOC-201, a room-temperature stable, polymerized, bovine-HBOC, as a substitute for allogenic RBC transfusion in patients undergoing elective infrarenal aortic operations. METHODS: In a single blind, multicenter trial, 72 patients were prospectively randomized two-to-one to HBOC (n = 48) or allogenic RBC (n = 24) at the time of the first transfusion decision, either during or after elective infrarenal aortic reconstruction. Patients randomized to the HBOC group received 60 g of HBOC for the initial transfusion and had the option to receive three more doses (30 g each) within 96 hours. In this group, any further blood requirement was met with allogenic RBCs. Patients randomized to the allogenic RBC group received only standard RBC transfusions. The efficacy analysis was a means of assessing the ability of HBOC to eliminate the requirement for any allogenic RBC transfusions from the time of randomization through 28 days. Safety was evaluated by means of standard clinical trial methods. RESULTS: The two treatment groups were comparable for all baseline characteristics. Although all patients in the allogenic RBC group required at least one allogenic RBC transfusion, 13 of 48 patients (27%; 95% CI, 15% to 42%) in the HBOC group did not require any allogenic RBC transfusions. The only significant changes documented were a 15% increase in mean arterial pressure and a three-fold peak increase in serum urea nitrogen concentration after HBOC. The complications were similar in both groups, with no allergic reactions. There were two perioperative deaths (8%) in the allogenic RBC group and three perioperative deaths (6%) in the HBOC group (P = 1.0). CONCLUSION: HBOC significantly eliminated the need for any allogenic RBC transfusion in 27% of patients undergoing infrarenal aortic reconstruction, but did not reduce the median allogenic RBC requirement. HBOC transfusion was well tolerated and did not influence morbidity or mortality rates.

Adult↗
PubMed2000

Viscoelastic properties of normal and atherosclerotic carotid arteries.

BACKGROUND: remodelling of the arterial wall occurs with ageing, even in the absence of atherosclerotic risk factors. With increasing age, arteries dilate, thicken, and get stiffer. The aim of this study was to correlate carotid artery stiffness with wall thickness and plaque presence between healthy individuals and patients with early and advanced atherosclerosis. METHODS: twenty healthy volunteers, 40 carotid segments and 90 patients, 174 carotid segments, with vascular disease were included in the study. The carotid artery was imaged longitudinally and measurements of the intimal-medial thickness (IMT) and plaque were obtained. Systolic and diastolic blood pressures were taken from each arm. The carotid artery stiffness (pressure-strain elastic modulus, Ep) was calculated in all sites from the changes in pressure and diameter. M-mode was used to detect the diameter change (systolic to diastolic) over five cardiac cycles. RESULTS: in the healthy volunteers there was no evidence of plaque or increased IMT. The mean IMT was significantly higher in the patients compared to control (0.83+/-0.27 mm vs. 0.54+/-0.08 mm, p <0.0001). The IMT had a poor correlation with Ep at lower thickness (r=0.24, p=0.08) but this association became stronger with increasing thickness (r=0.62, p<0.001). Arterial segments with an IMT 5 0.88 mm became significantly stiffer compared to the controls (p<0.001) and to patients with an IMT<0.88 mm (p <0.01). Carotid Ep was markedly greater in arterial segments with plaques than in those with increased IMT (p <0.001) and the controls (p<0.0001). CONCLUSIONS: carotid wall areas with small increase in IMT have a poor correlation with carotid artery stiffness. The carotid stiffness increases in areas with marked wall thickening and particularly in segments with plaque. The simultaneous study of vessel-wall elastic behaviour with IMT and plaque changes may increase our understanding of atherosclerotic progression and wall remodelling.

Adult↗
PubMed2000

Optimising the performance of intermittent pneumatic compression devices.

OBJECTIVES: this study was designed to determine whether an intermittent pneumatic compression device (IPC) with an increased maximal inflation pressure, a decreased time to maximal pressure and a longer duration of compression would improve venous return compared to a standard IPC device. METHODS: thirty limbs in 15 volunteers without evidence of venous disease were studied using duplex scanning at rest and during the application of two different IPC devices with different compression parameters. The first device IPC-1 (SCD 5325, Kendall) has a six-chambered cuff applying 45 mmHg after 12 s, sequentially from ankle to thigh followed by 60 s of non-compression. The second device IPC-2 (Vena-Assist(R), ACI Medical) has a foot, ankle and calf cuff, applies a pressure of 80 mmHg, has a pressure rise time of 0.3 s, maintains inflation for 5.5 s, and has a cycling time of 1 min. Peak venous velocity and acceleration time were measured at rest and during the IPC application. Measurements were obtained in supine position from the common femoral vein 1 cm above the saphenofemoral junction to include the entire venous outflow from the limb. RESULTS: peak venous velocity at rest was significantly higher in the right limb than in the left limb (26+/-7.2 vs. 22+/-5.7 cm/s, p<0.01). Peak venous velocity was significantly increased by both IPC devices (p <0.0001). IPC-2 achieved significantly higher peak venous velocity than IPC-1 (55.1+/-17.8 vs. 37.4+/-6.9 cm/s, p<0.0001). Acceleration time was also found to be significantly shorter (370+/-93.4 vs. 560+/-83.5 ms, p<0.0001) in IPC-2 than in IPC-1, respectively. CONCLUSIONS: we have demonstrated that progressive inflation at the foot, ankle and calf, increasing maximal inflation pressure and decreasing time to maximal pressure result in increased venous return. These changes may improve the efficacy of IPC devices in the prevention of deep-venous thrombosis (DVT) formation.

Adult↗
PubMed2000

Prevalence of deep venous reflux in patients with primary superficial vein incompetence.

PURPOSE: This prospective study was designed to determine the prevalence of deep reflux and the conditions under which it may occur in patients with primary superficial venous reflux and absence of deep venous thrombosis (DVT). METHODS: We studied 152 limbs in 120 consecutive patients in the standing position who had superficial venous reflux with color flow duplex scanning. Limbs with documented evidence of DVT or post-thrombotic vein wall changes during the examination were studied but not included in the analysis. Limbs were divided into those that had at least reflux in the saphenofemoral, the saphenopopliteal, or the gastropopliteal junction and into those with nonjunctional reflux in the superficial and gastrocnemial veins. Peak velocity and duration of reflux were measured. To examine the recirculation theory, we tested the deep veins by occluding and refluxing saphenous veins 10 cm below the sampling site. RESULTS: Thirteen limbs in 11 patients (9%) were excluded because of previous DVT. Of the remaining 139 limbs, 106 (76%) had junctional reflux. Saphenofemoral junction was involved in 89 limbs (84%), saphenopopliteal junction in 18 (17%), and gastropopliteal junction in 7 (4%). In 33 limbs (24%), reflux was detected in the main trunk or tributaries of the saphenous veins alone with no junctional incompetence. Femoral or popliteal reflux was present in 31 limbs (22%). This reflux was segmental in 27 limbs, and it was limited in the junction in 24 limbs. The mean duration of deep venous reflux was 0.9 seconds, it ranged from 0.6 to 3.7 seconds, and it was significantly shorter than that in the superficial veins (2.6 seconds; P <.0001). In the absence of junctional reflux, the prevalence of deep venous insufficiency (DVI) was significantly lower compared with that in limbs with junctional involvement (2 of 33 vs 29 of 106; P =.038). The mean duration of deep venous reflux in these groups was comparable (0.85 seconds vs 0. 91 seconds; P =.44). Occlusion of the incompetent superficial veins reduced somewhat the duration of the deep venous reflux but did not abolish it (0.88 seconds vs 0.82 seconds; P =.072). The presence of DVI was associated with junctional reflux of high peak velocity and long duration. CONCLUSIONS: The prevalence of DVI in patients with primary superficial venous reflux and without history of DVT is 22%. However, this reflux is segmental, mainly in the common femoral vein, and is of short duration. It is associated with the presence of junctional incompetence that has a high peak velocity and long duration. These findings may explain why surgical correction of superficial reflux abolishes DVI.

Adult↗
PubMed2000

The impact of isolated lesser saphenous vein system incompetence on clinical signs and symptoms of chronic venous disease.

PURPOSE: The purpose of this study was to determine the patterns of isolated lesser saphenous vein (LSV) system incompetence and correlate the distribution and extent of such reflux with symptoms and signs of chronic venous disease (CVD). METHODS: During a 3-year period, 2254 limbs in 1682 patients with signs and symptoms of CVD were evaluated with color flow duplex scanning. Extremities with isolated reflux in the LSV system were selected for this study. Limbs with perforating venous reflux connected to this system only were also included. Limbs that had marked reflux in the greater saphenous or deep vein, that had a documented history of deep venous thrombosis, and that previously underwent surgery or sclerotherapy were excluded. The clinical severity of the limbs was graded with the CEAP classification system. RESULTS: There were 226 limbs in 200 patients with reflux in the LSV system; 61% were female patients with a mean age of 49 years (range, 18-82 years). There were 174 patients (87%) with unilateral and 26 with bilateral disease, and 41% of the limbs belonged in CVD class 2, 26% in class 3, 12% in class 4, 3.5% in class 5, and 3% in class 6. Classes 0 and 1 were present in 14.5% of the limbs. Symptoms were present in 139 limbs (61.5%). Some degree of ache or burning sensation was the most frequent symptom (41%), followed by itching (32%), heaviness (29%), cramps (24%), and restless limbs (18%). Reflux in the main trunk of the LSV was the most prevalent (177 limbs [78%]), followed by the saphenopopliteal junction (146 limbs [64.6%]), the vein of Giacomini (39 limbs [17%]) and the gastrocnemial vein (23 limbs [10%]). Reflux involving both the saphenopopliteal junction and the LSV was seen in 50% of limbs, but almost any other combination of reflux was present, which indicated the complexity of this system. Perforator vein incompetence was detected in 56 limbs (25%). We found 83 perforator veins, resulting in a mean of 1.5 veins per limb. Both the number of incompetent perforator veins and the extent of superficial reflux correlated with clinical severity. Four main types of termination of the LSV were identified with at least nine variations. The LSV was duplicated for at least half of its length in five limbs (2.2%). Nonsaphenous reflux was detected in seven limbs (3.1%). Superficial vein thrombosis in the LSV system was found in eight limbs (3.5%), and in the gastrocnemial vein it was found in four (1.8%). CONCLUSIONS: Isolated LSV system incompetence can cause the entire range of signs and symptoms of CVD. Clinical deterioration is associated with a longer extent of reflux and perforator incompetence. Classes 2 to 4 are the most frequent clinical presentations, whereas classes 5 and 6 are uncommon. The complex anatomy of this system and the great variation in the patterns of reflux warrant the use of color flow duplex scanning before planning treatment.

Adolescent↗
PubMed2000

A 90-day drinking water toxicity study in rats of the environmental contaminant ammonium perchlorate.

Perchlorate (ClO(4)(-)), the dissociated anion of perchlorate salts such as ammonium, potassium, and sodium perchlorate, has been recently recognized as a persistent and pervasive contaminant of drinking water supplies in a number of metropolitan areas. Perchlorate is of concern because of uncertainties in the toxicological database available to address the potential human health effects of low-level exposure. The purpose of this study was to evaluate the subchronic toxicity of perchlorate when administered to Sprague-Dawley rats as ammonium perchlorate (AP) for 14 or 90 days. The study consisted of an untreated control group and five treatment groups that received continuous exposure to AP via the drinking water at dosage levels of 0.01, 0.05, 0.2, 1.0, and 10.0 mg/kg/day. The study design included a nontreatment recovery period of 30 days to evaluate the reversibility of any AP-induced effects at the 0.05, 1.0, and 10.0 mg/kg/day levels. The study also investigated the potential effects of AP on male sperm parameters, female estrous cyclicity, bone marrow micronucleus formation, and serum hormone levels, i.e., triiodothyronine (T(3)), thyroxine (T(4)), and thyroid stimulating hormone (TSH). No toxicologically meaningful differences were observed between the control and AP-treated groups with respect to survival, clinical observations, body weights, food consumption, water consumption, ophthalmology, hematology, clinical chemistry, estrous cycling, sperm parameters, or bone marrow micronucleus formation. A target organ effect was produced by AP in the thyroids of male and female rats at the 10 mg/kg/day level after 14 and 90 days of exposure. The effect was characterized by significantly increased thyroid weights and thyroid histopathology consisting primarily of follicular cell hypertrophy with microfollicle formation and colloid depletion. These changes were reversible after a nontreatment recovery period of 30 days. Statistically significant changes in TSH and thyroid hormones were observed at all AP dosage levels tested; however, no thyroid organ weight or histopathological effects were observed at AP dosage levels < or = 1.0 mg/kg/day. In the absence of thyroid organ weight and histopathological effects, the toxicological significance of TSH and thyroid hormone changes at AP dosage levels < or = 1.0 mg/kg/day remains to be determined.

Animals↗
PubMed2000

A prospective study of the effects of irradiation on the carotid artery.

OBJECTIVES/HYPOTHESIS: To prospectively assess the effects of irradiation on the carotid artery in patients with head and neck cancer, as a possibly relevant factor in cancer treatment planning. STUDY DESIGN: Prospective study from a tertiary care academic setting on university (22 patients) and Veterans Affairs (14 patients) hospital patients; 1-year follow-up, including comparison of study data with age-matched and sex-matched control subjects from epidemiological studies. METHODS: Thirty-six patients with head and neck cancer who underwent therapeutic neck irradiation were examined by high-resolution ultrasound before and 1 year after treatment. Twelve patients were also studied at 2 years. Measurements included the intima-media thickness (IMT) of the carotid artery wall, the degree of stenosis as estimated from velocity measurements, and the presence and size of plaque. RESULTS: The pretreatment carotid IMT at baseline was 0.68 mm and was comparable to age-matched and sex-matched control subjects. Significant increase in the IMT was observed on both the left (0.67 vs. 0.84 mm) and the right (0.7 vs. 0.87 mm) sides (P < .001) 1 year after irradiation. In 12 patients who completed 24 months of follow-up the carotid IMT continued to significantly increase statistically compared with that at the first year after treatment (left side, 0.79 vs. 0.85 mm, P = .037; right side, 0.79 vs. 0.95 mm, P = .014). Statistically significant thickening of the carotid wall developed in all 36 patients by 1 year. Two patients experienced post-treatment neurological events and an area of stenosis greater than 75%. CONCLUSIONS: Neck irradiation significantly increases the thickness of the carotid wall during the first year after treatment--on average, 21 times more than in epidemiologically matched control volunteers. This phenomenon should be taken into consideration when planning treatment for the node-negative (NO) neck.

Carcinoma, Squamous Cell↗
PubMed2000

Effect of contralateral occlusion on long-term efficacy of endarterectomy in the asymptomatic carotid atherosclerosis study (ACAS). ACAS Investigators.

BACKGROUND AND PURPOSE: The Asymptomatic Carotid Atherosclerosis Study (ACAS) established the effectiveness of prophylactic carotid endarterectomy, for patients in good health who had stenosis >/=60%, if conducted by surgeons with a surgical morbidity and mortality of <3%. This secondary analysis was performed to determine whether the presence of contralateral cervical carotid occlusion alters the efficacy of asymptomatic ipsilateral carotid endarterectomy. METHODS: One hundred sixty-three participants who had a baseline contralateral occlusion documented by Doppler ultrasound (77 medical, 86 surgical) were compared with 1485 participants with a patent contralateral carotid artery (748 medical, 737 surgical) for the risk of a combined end point of perioperative (30-day) death or stroke or long-term (5-year) ipsilateral stroke. RESULTS: For those without contralateral occlusion, surgery was associated with a 6.7% absolute reduction in the 5-year risk (95% CI, 2.1% to 11.4%), while for those with a contralateral occlusion, surgery was associated with a 2.0% absolute increase in risk (95% CI, -9.3% to 5.2%), which was a statistically significant difference in the effect of surgery (P:=0.047). This difference is primarily attributable to low long-term risk for medically managed patients with contralateral occlusion. CONCLUSIONS: While this post hoc analysis should be interpreted with caution, the findings suggest that endarterectomy in asymptomatic subjects with contralateral occlusion provides no long-term benefit (and may be harmful) in preventing stroke and death. These findings were a result of the benign course of medically treated subjects.

Aged↗