A Specific Thromboxane Receptor Blocking Drug, AH23848, Reduces Platelet Deposition on Vascular Grafts in Man

The antithrombotic effect of a specific thromboxane A2 receptor blocking drug, AH23848, on radio-labelled platelet deposition in mature Dacron aorto-bifemoral grafts has been evaluated in patients. Thirty patients were randomly allocated to AH23848 70 mg, aspirin 300 mg plus dipyridamole 75 mg or placebo 8-hourly for 9 days. AH23848 inhibited platelet aggregarion induced by the thromboxane ,A2 mimetic U-46619; no such effect was observed with aspirin plus dipyridamole. 111In-platelet uptake was measured as the thrombogenicity index (TI) which is a measure of the daily rate of accumulation of platelets by the graft. The mean (s.e. mean) value of 0.193 (0.029) on placebo was significantly reduced to 0.115 (0.022) by AH23848 (p <0.05) but only to 0.175 (0.028) by aspirin plus dipyridamole. There was no difference in mean platelet life span between the three treatment groups. The pronounced antithrombotic effect of AH23848 implicates thromboxane ,A2 in the process of platelet deposition in arterial prostheses and demonstrates the considerable promise of thromboxane receptor blocking drugs as antithrombotic therapy.

The Effects of Thromboxane Antagonism on the Transit Time of Platelets Through the Spleen

The spleen is well-known as a site for platelet pooling, although the mechanisms controlling intrasplenic platelet transit are essentially unknown. We tested the possibility that thromboxane A2 might be involved in this control by measuring intrasplenic platelet transit time in 10 subjects receiving a specific thromboxane A2 receptor antagonist (AH23848B; 70 mg; Glaxo Group Research Ltd), in 10 receiving aspirin (300 mg) plus dipyridamole (75 mg), and in 9 receiving placebo. All doses were administered 3 times daily commencing 4 days prior to transit time measurement.

Mean intrasplenic platelet transit time was measured by monitoring the kinetics of equilibration of 111In radiolabelled platelets between blood and spleen following intravenous injection. There was no difference between the mean transit time in the 3 groups of subjects, lending no support to the hypothesis that thromboxane A2 is involved in the control of platelet traffic through the spleen.

Lower Limb Neutrophil Oxygen Radical Production is Increased in Venous Hypertension

Objective:

To investigate neutrophil free radical production in patients with venous hypertension.

Patients:

Thirteen legs in patients with venous ulceration were compared with seven legs in patients suffering from lipodermatosclerosis (LDS) only and nine normal controls.

Design:

Leg and arm venous blood samples were obtained from each patient after a period of 30 min of leg dependency followed by elevation to the horizontal for a further 5 min. Neutrophils were isolated and free radical production assessed by luminol-dependen t chemiluminescence following stimulation with the chemotactic peptide FMLP.

Results:

The ratio of leg to arm luminescence was significantly higher in patients with venous ulceration (median 1.61; 95% confidence interval (CI) 1.20–3.05; p=0.0002) and those with LDS (median 1.36; 95% CI 1.05–2.01; p=0.0036) when compared with the controls (median 0.97; 95% CI 0.70–1.12).

Conclusions:

Neutrophil free radical production is increased in the legs of patients with venous hypertension and may be implicated in the underlying pathogenesis of this disease.

Student performance and course evaluations before and after use of the Classroom Performance System ™ in a third-year veterinary radiology course

Effective teaching of veterinary radiology can be challenging in a traditional classroom environment. Audience response systems, colloquially known as "clickers," provide a means of encouraging student interaction. The purpose of this study was to compare student performance and course evaluations before and after using the Classroom Performance System™ in the third-year (fifth semester) didactic radiology course at the University of Tennessee College of Veterinary Medicine. Overall student performance was assessed by comparing median numeric final course grades (%) between years without and with use of the Classroom Performance System™. Grades of students were determined for individual instructors' sections. Student evaluations of the radiology course were compared for the years available (2007-2010). Student interactions were also evaluated subjectively by instructors who used the Classroom Performance System™. There was a significant difference (p = 0.009) between the median student grade before (2005 - 2008, median 82.2%; interquartile range 77.6-85.7%; range 61.9-95.5%) and after use of the classroom performance system (2009-2010, median 83.6%; interquartile range 79.9-87.9%; range 68.2-93.2%). There was no statistically significant difference in median student grades for individual instructors over the study period. The radiology course student evaluation scores were significantly higher in years where the Classroom Performance System™ was used in comparison to previous years (P = 0.019). Subjectively, students appeared more involved when using clickers. Findings indicated that the Classroom Performance System™ may be a useful tool for enhancing veterinary radiology education.

Outcome of 112 consecutive patients with an abdominal aortic aneurysm greater than 5·5 cm turned down for elective repair at a university hospital

Background

The UK Small Aneurysm study has demonstrated the low risk of rupture in aneurysms less than 5·5 cm in diameter. However, the natural history of aneurysms greater than 5·5 cm remains unresolved. Questions of equipoise probably preclude another trial in patients with an AAA over 5·5 cm. In this centre, the authors prospectively maintain records of all patients refused elective aneurysm surgery. This study aimed to document the outcome of all patients referred with an AAA greater than 5·5 cm in diameter, and to determine the cause of death and risk of rupture in all patients.

Methods

Details of all patients presenting with an AAA from 1989 to 1999 were recorded and demographic details on all patients with an AAA greater than 5·5 cm were collected. The endpoint was 1 May 1999. Copies of death certificates for deceased patients were obtained from the Office of National Statistics, local in-hospital patient records and general practitioner records. Results of post-mortem examinations were also retrieved. Aneurysms were stratified according to size at presentation (5·5–5·9, 6·0–7·0, more than 7·0 cm) and reasons for non-intervention were documented.

Results

Some 112 patients were turned down over 10 years (11·4 per year). The mean(s.d.) age of this patient group was 77·7(7·7) years; there were 74 men and 38 women. Crude mortality data are shown in the Fig. below (Kaplan–Meier curve). At the end of the study period, 87 patients (76 per cent) were dead, 26 (30 per cent) from a ruptured AAA. Mean survival times were: 23 months (5·5–5·9 cm), 20 months (6·0–7·0 cm) and 15 months (greater than 7·0 cm).

Conclusion

While recognizing the problems with death certification, rupture still seems to be a significant cause of death in patients with untreated AAAs greater than 5·5 cm. While little difference is observed in 5·5–7·0-cm range, patients with an AAA greater than 7·0 cm seem to have a much poorer prognosis.

Prognosis of patients turned down for conventional abdominal aortic aneurysm repair in the endovascular and sonographic era: Szilagyi revisited?

PURPOSE

The United Kingdom Small Aneurysm study has demonstrated the low risk of rupture in aneurysms less than 5.5 cm in diameter. With the advent of endoluminal techniques, patients considered unfit to undergo laparotomy are now considered for endovascular repair. However, the natural history of aneurysms larger than 5.5 cm remains uncertain, especially when severe comorbidity is present. In our center, we prospectively maintain records of all patients for whom elective aneurysm surgery was refused. This study documented the outcome of all patients referred with abdominal aortic aneurysms (AAAs) larger than 5.5 cm in diameter who were turned down for elective open repair and determined the cause of death and risk of rupture in all patients.

METHODS

Details of all patients with AAAs from January 5, 1989, to January 5, 1999, were recorded, and demographic details on all patients with AAAs larger than 5.5 cm were collected. Copies of death certificates were obtained from the Office of National Statistics, local in-hospital patient records, and general practitioner records. Results of postmortem examinations were also obtained. Aneurysms were stratified according to their size at presentation (5.5-5.9 cm, 6.0-7.0 cm, and > 7.0 cm), and the reasons no intervention was made were documented.

RESULTS

A total of 106 patients were turned down for elective aneurysm surgery in the 10-year period (10.6 per year). The mean age of the patients was 78.4 years (SD, 7.4), and 70 were men and 36 were women. At the end of the study, 76 patients (71.7%) had died. Overall, the 3-year survival rate was 17%. Patients with AAAs larger than 7.0 cm lived a median of 9 months. A ruptured aneurysm was certified as a cause of death in 36% of the patients with an AAA of 5.5 to 5.9 cm, in 50% of the patients with an AAA of 6 to 7.0 cm, and 55% of the patients with an AAA larger than 7.0 cm. Reasons given for not intervening were patient refusal (31 cases), the patient being "unfit for surgery" (18 cases), the "advanced age" of the patient (18 cases), cardiac disease (9 cases), cancer (9 cases), respiratory disease (6 cases), and other (15 cases).

CONCLUSION

Although we recognize the problems with death certification, we found that rupture was a significant cause of death in patients with an untreated AAA that was larger than 5.5 cm. Although little difference in outcome was observed in aneurysms in the 5.5 to 7.0 cm size range, patients with an AAA that was larger than 7.0 cm seemed to have a much poorer prognosis.

Quantitative urinalysis in healthy Beagle puppies from 9 to 27 weeks of age

To evaluate indices of renal function in healthy, growing Beagle puppies from 9 to 27 weeks of age and to determine whether indices change with age during this period. Animals-6 healthy Beagle puppies.

PROCEDURE

Urine collections were performed at 2-week intervals in puppies 9 to 27 weeks old. Daily excretion of urinary creatinine, protein, sodium, potassium, chloride, phosphorus, and calcium were determined, as were quantitative urinalyses including endogenous creatinine clearance, urine protein-to-creatinine ratios (UPr/C), and fractional clearances of sodium (FNa), potassium (FK), chloride (FCI), calcium (FCa), and phosphorus (FP).

RESULTS

Significant differences among age groups were detected for endogenous creatinine clearance, and daily urinary protein, potassium, calcium, and phosphorus excretion. Significant differences also existed among age groups for UPr/C, FNa, FK, FCI and FP. Age-related effects fit a linear regression model for FNa, UPr/C, daily phosphorus excretion, and daily protein excretion. Quadratic regression models were judged most appropriate for endogenous creatinine clearance, FK, daily chloride excretion, and daily potassium excretion. Endogenous creatinine clearance measurements higher than adult reference ranges were observed from 9 to 21 weeks of age. The FNa, FK, FCI, FCa, and FP were slightly higher than those reported for adult dogs.

CONCLUSIONS AND CLINICAL RELEVANCE

Selected results of quantitative urinalyses in healthy 9- to 27-week-old Beagle puppies differ with age and differ from those measured in adult dogs. Diagnostic measurements performed in puppies of this age range should be compared with age-matched results when possible.

Functional urethral obstruction in 3 dogs: clinical and urethral pressure profile findings

Three dogs with dysuria and urine retention caused by excessive functional urethral resistance are described. All dogs had clinical histories and urologic signs that previously would have been classified as detrusor-urethral dyssynergia. Diagnosis of functional urinary obstruction was established by exclusion of anatomic urinary obstruction and confirmed by urethral pressure profilometry. In 2 cases, multiple pressure deflections recorded in the urethral pressure profile suggested spasm of urethral musculature, whereas in a 3rd dog, abnormally high pressures were recorded along a portion of the proximal urethra. Functional urinary obstruction was associated with prostatitis in 1 dog and with a history of urethral calculi in 1 dog, and no underlying disorder could be identified in the remaining dog. All 3 dogs improved with medical treatments that included alpha adrenergic antagonists. The etiology, diagnosis, and pharmacologic management of functional urinary obstruction are discussed.

Diagnosis and management of urinary retention

Failure to empty the urinary bladder completely can be attributed to failure of detrusor contractile function, inappropriate outlet resistance, or both. For each of these mechanisms, anatomic, neurogenic, and end-organ (myogenic or idiopathic) abnormalities are possible. The approach to urinary retention involves systematic consideration of neurogenic, obstructive, and functional causes and requires understanding of the neurophysiology and pharmacology of micturation.

Is there carotid artery aneurysm formation following saphenous vein patch endarterectomy?

The use of saphenous vein patching following carotid endarterectomy is reported to produce aneurysmal dilatation with the risk of thrombosis and possible rupture. The authors have studied patients who have had saphenous vein patch angioplasty following carotid endarterectomy to assess whether there is any progressive arterial dilatation. Thirty-five patients who had undergone saphenous vein patch carotid endarterectomy were age- and sex-matched with 31 subjects that had direct closure endarterectomy. All participants underwent carotid duplex scanning. The external diameters of the mid common carotid artery, the bulb and the proximal internal carotid artery were measured bilaterally. The diameters of the endarterectomized carotid were compared with the contralateral side using a paired t-test. Using an unpaired t-test, the saphenous vein angioplasty group was compared with the directly closed group. A graph was plotted of the ratio of internal carotid artery diameter of the saphenous vein angioplasty group (endarterectomized artery to the contralateral artery) against the length of follow-up, and the Pearson correlation coefficient was calculated. When the saphenous vein angioplasty group was compared with the directly closed group there was a significant difference between the carotid bulb (11.6 versus 9.7mm, P < 0.001) and internal carotid artery diameters (9.0 versus 7.0mm, P < 0.001). Longitudinal analysis of the saphenous vein angioplasty group showed that the increased diameter of the endarterectomized internal carotid artery progressed with time after surgery (r = 0.51, P < 0.005, and r = 0.56, P < 0.001). Vein patching increases the diameter of the internal carotid artery, and this may further increase with time possibly predisposing to aneurysm formation. Further longitudinal studies of paired data are required.

Parenteral nutrition in the management of a dog with lymphocytic-plasmacytic enteritis and severe protein-losing enteropathy

Management of lymphocytic-plasmacytic enteritis in a dog with whipworm infestation, hypoproteinemia, and ascites is described. Short-term parenteral nutrition hastened normalization of serum proteins, resolution of diarrhea, and weight gain. A description of the potential benefits, limitations, and possible complications of parenteral nutrition in refractory inflammatory bowel disease is given.

Profound postanesthetic hypoglycemia attributable to glucocorticoid deficiency in 2 dogs

Glucocorticoid deficiency was diagnosed as the cause of severe postanesthetic hypoglycemia in 2 dogs. Prior signs of systemic illness were not described in either dog; however, preoperative hematologic findings were consistent with glucocorticoid deficiency. Fasting hypoglycemia is a possible complication of chronic adrenal insufficiency primarily because of impaired gluconeogenesis.

Methods for studying leukocyte filterability in undiluted blood from intermittent claudicants

Leukocytes are characterised from their influence on the filterability of undiluted blood from patients with PAOD (intermittent claudicants - Fontaine Stage II) and a group of sex and age-matched controls. Undiluted blood was filtered through 5 microm Nuclepore (Hemafil) filters for 300 s, at 711 Pa and room temperature, using a custom-made constant pressure filtrometer. Four populations of leukocytes are identified in both groups. In the control group, 94.4% of the leukocytes are identified as fast leukocytes with a transit time of 1.8 s. The remaining white cells are recognised as slow flowing leukocytes and subdivided into three further sub-populations. The first of these (SL1; 2.8% of total leukocyte count) is characterised by a transit time of 31.7 s, a second population (SL2; 1.5% of total leukocyte count) by a transit time of 145.8 s while the remaining cells are identified as pore blockers (PB) under these conditions. A similar rheological classification is valid in the patients but the sum of the three minor populations is elevated compared to controls (p = 0.001) although there is no overall leukocytosis. The only significant difference in flow properties of any blood cells, between the two groups of volunteers, is seen in the major population of leukocytes with an elevated transit time of 2.4 s. Stepwise regression analysis identifies the concentration of fast leukocytes, SL2 and PB as the major variables affecting blood flow through the filter. It is argued that the higher concentration of SL2 and PB probably reflect the increased sensitivity of neutrophils to physical stimuli.

Leucocyte filterability: comparing diluted with undiluted blood

Red blood cells and about 95% of white blood cells have an immediate and constant effect on the flow of undiluted or diluted blood through 5 microm filters. The remaining 5% of all leucocytes exert an increasing influence on flow such that the rate of flow of diluted and undiluted blood through these filters is continually declining over a period of 150 s. Analysis of this declining flow rate enables these cells to be counted and their rheological properties to be deduced. Approximately 50% of these slow leucocytes pass through the filters with a transit time of about 30 s and the remaining cells act as pore blockers for 150 s. The numbers and flow properties of slow leucocytes was approximately the same in blood from young women (25 years) and older men (65 years). However, the number of slow leucocytes was increased in a group of men (65 years) suffering from peripheral arterial occlusive disease. Dilution of the blood with phosphate-buffered saline increased the numbers of slow leucocytes in both of the older, but not the younger, group of volunteers. This effect was particularly noticeable in the patient group. It is recommended that filtration studies of the rheological profile of leucocytes can, and must, be performed with undiluted blood. The properties after dilution may sometimes, but not invariably, reflect changes ex vivo as well as inherent differences in the cells themselves.

Dynamic obstruction of the external iliac artery in endurance athletes and its relationship to endothelial function: the case of a long distance runner

There have been recent reports of exercise induced claudication in endurance trained athletes attributed to narrowing of the external iliac artery. Most patients have been competitive cyclists, and intimal hyperplasia has been cited as the cause. The case is reported here of a long distance runner who presented with similar symptoms.

The effects of platelet inhibitors on platelet uptake and restenosis after femoral angioplasty

OBJECTIVE

To investigate the effects of two platelet inhibitors, aspirin and iloprost, on platelet uptake and restenosis at the site of angioplasty in patients undergoing femoral or popliteal angioplasty.

EXPERIMENTAL DESIGN

Prospective, open, randomised group comparison.

SETTING

Two university hospitals.

PATIENTS

43 patients undergoing femoral or popliteal angioplasty were randomised.

INTERVENTIONS

Patients received either aspirin (300 mg/day), iloprost (8 hours/day i.v. infusion) or no antiplatelet medication during angioplasty and on the subsequent two days.

MEASURES

Platelet uptake was measured using 111Indium-labelled platelets. Restenosis was assessed by repeat angiography at 3 months and clinical symptoms up to 12 months.

RESULTS

Median changes in platelet uptake were similar in the three treatment groups, but all platelet radioactivity ratios > 2.0 occurred in the control group. Restenosis at 3 months was observed in 3 control, 5 aspirin and 1 iloprost patient. Further surgical intervention was performed in 3 control and 3 aspirin patients, but in none of the iloprost patients up to 12 months after angioplasty.

CONCLUSIONS

Antiplatelet therapy may prevent large increases in platelet deposition at the angioplasty site, but the link between platelet deposition and restenosis was not substantiated in this study.

Comparison of clinical follow-up and duplex surveillance of infrainguinal vein bypasses

The evidence in support of surveillance has been principally based on the favourable primary-assisted patency of stenosed grafts following revision (60-80% at 5 years) compared with the poor secondary patency of revised occluded grafts (20-40% at 5 years). Both the capital cost and workload generated by surveillance are considerable. More information is needed on the benefits of surveillance compared with clinical follow-up. A retrospective comparison of 50 vein grafts (44 reversed, six in situ) undergoing colour-coded duplex surveillance and 50 vein grafts (46 reversed, four in situ) under clinical follow-up, with duplex scans obtained only when clinically indicated, has been performed. Four (8%) stenoses of > or = 50% were identified in the surveillance group. One 50% proximal anastomotic stenosis failed to progress on sequential scans. Three stenoses were treated (one mid graft, two popliteal) by vein patch angioplasty (two cases) and transluminal angioplasty (one case). Both groups were followed-up for 12 months. Secondary patency at 12 months (88% surveillance; 80% clinical follow-up) was not significantly different (P = 0.3). Similarly, limb salvage at 12 months (94% surveillance; 88% controls) was not significantly different (P = 0.4). A large randomized prospective study comparing duplex surveillance and clinical follow-up is warranted.

The influence of total knee arthroplasty on lower limb blood flow

Ischaemic complications of total knee arthroplasty (TKA) are unusual and tend to occur in patients with peripheral vascular disease (PVD). A prospective study was undertaken to investigate the effect of TKA on blood flow in patients without clinical evidence of PVD. Ankle brachial index (ABI) did not alter post-operatively and no changes in arterial waveforms were found. Unless there is clinical evidence of PVD, TKA under tourniquet control is therefore very unlikely to cause ischaemic complications.

Colour-coded duplex assessment alone before carotid endarterectomy

This study assessed whether carotid colour-coded duplex imaging can provide sufficient information to investigate patients before carotid endarterectomy. One hundred patients with symptomatic carotid artery disease (amaurosis fugax 24, transient ischaemic attack 38 and established stroke 38) were assessed by both colour-coded duplex imaging and arch angiography. Stenoses were graded at angiography using the linear method from the European Carotid Surgery Trial and on duplex using peak systolic velocity criteria. Angiograms were also analysed for any arch or intracerebral pathology which would alter surgical management. In defining 70-99 per cent stenoses, duplex had a sensitivity of 98 per cent, specificity 96 per cent, positive predictive value of 96 per cent, negative predictive value 98 per cent and accuracy 97 per cent compared with angiography for both symptomatic and asymptomatic carotids (chi 2 = 1.22, 1 d.f., P = 0.25). With respect to the symptomatic carotid arteries angiography gave different information from duplex in six patients (6 per cent): definition of 70-99 per cent carotid stenosis was different (four), visualization was poor on duplex (one) and an intracerebral aneurysm was identified by angiography. One patient died following arch angiography as a result of mesenteric thrombosis. Carotid duplex imaging alone would appear to be sufficient to assess most patients before carotid endarterectomy as an accurate, safe and relatively cheap investigation compared with angiography. In cases where duplex assessment does not allow full visualization of the carotid bifurcation angiography is required.

Feline urodynamic procedures

Urodynamic procedures are those studies which investigate the process of storage and evacuation of urine in the lower urinary tract, usually by recording pressure or flow characteristics in the urinary bladder or urethra. Cystometric techniques, urethral pressure profilometry, electromyography, and evoked potentials have been adapted for use in cats. The applications and limitations of each of these techniques are discussed.

Pharmacologic management of feline lower urinary tract disorders

Pharmacological recommendations for the treatment of lower urinary tract disorders in cats are rapidly evolving as more is learned about the physiology and pathophysiology of the feline urinary bladder and urethra. Recent investigations and clinical observations have led to reconsideration of previously prescribed treatments and to the use of new and alternative pharmacologic agents. Pharmacologic agents used in the management of common lower urinary tract disorders in cats, including urinary tract infections, idiopathic lower urinary tract inflammation, urinary incontinence, urine retention, and urinary elimination disorders, are reviewed.

Flush saphenofemoral ligation and multiple stab phlebectomy preserve a useful greater saphenous vein four years after surgery

PURPOSE

Flush saphenofemoral ligation, with multiple cosmetic stab phlebectomy, successfully treats saphenofemoral reflux and superficial varicosities. The long-term effect on the residual greater saphenous vein (GSV) requires evaluation.

METHODS

Noninvasive triplex ultrasound assessment of the residual GSV for potential use as a vein graft was used. We evaluated the independent objective and subjective cosmetic outcomes. We also used analysis to determine the correlation between GSV reflux, symptoms, and cosmetic outcome.

RESULTS

Seventy-two limbs were assessed at a median follow-up of 4 years (interquartile range 3 to 5 years). Fifty-nine limbs had patent GSVs above and below the knee. The mean length patent was 51 cm, and the mean internal diameters above and below the knee were 3.6 and 2.8 mm, respectively. In 65% of cases the vein had suitable ultrasonic characteristics, suggesting that it would be suitable for use as a conduit for a vascular bypass graft. Sixty-two limbs were considered a symptomatic success and 61 an objective cosmetic success. There was no correlation between the symptomatic and cosmetic outcome and the presence of superficial GSV reflux (linear regression analysis).

CONCLUSIONS

These findings support the effectiveness of the procedure of flush saphenofemoral ligation and multiple stab phlebectomy with regard to cosmetic and symptomatic outcome and may preserve the GSV for use as an autologous bypass graft.

Vascular trauma in civilian practice

Vascular trauma is associated with major morbidity and mortality, but little is known about its incidence or nature in Britain. A retrospective study of 36 patients requiring operative intervention for vascular trauma under one vascular surgeon over a 6-year period was undertaken. Twenty-four patients suffered iatrogenic trauma (median age 61 years); including cardiological intervention (19), radiological intervention (2), varicose vein surgery (1), umbilical vein catherisation (1) and isolated hyperthermic limb perfusion (1). There were 23 arterial and three venous injuries. Twelve patients had accidental trauma (median age 23 years). Three of the ten patients with blunt trauma were referred for vascular assessment before orthopaedic intervention, two after an on-table angiogram and five only after an initial orthopaedic procedure (range of delay 6 h to 10 days). Injuries were arterial in nine, venous in two and combined in one. Angiography was obtained in six patients, and in two patients with multiple upper limb fractures identified the site of injury when clinical localisation was difficult. A variety of vascular techniques were used to treat the injuries. Two patients died postoperatively and one underwent major limb amputation. Thirty-two (89%) remain free of vascular sequelae after a median follow-up of 48 months (range 3-72 months). Vascular trauma is uncommon in the United Kingdom. To repair the injuries a limited repertoire of vascular surgery techniques is needed. Therefore, vascular surgical assessment should be sought at an early stage to prevent major limb loss.

Evaluation of results of preoperative urodynamic measurements in nine dogs with ectopic ureters

Cytometrographic studies and urethral pressure profiles were performed to objectively assess the functional status of the urinary bladder and urethra in 9 dogs with congenital ectopic ureters. Functional abnormalities of the urinary bladder or urethra were detected in 8 of 9 (89%) dogs. Cystometrographic evidence of reduced bladder capacity was detected in 4 (44%) dogs, and abnormalities in urethral pressure profiles were consistent with urethral incompetence in 6 (67%) dogs. Dogs with urethral pressure profile abnormalities were treated with phenylpropanolamine hydrochloride, and the urethral pressure profile was reevaluated. Urethral pressure measurements obtained before surgery (3 dogs) and after phenylpropanolamine (6 dogs) were used to predict the likelihood of continence after surgery. Predicted outcomes included continence maintained without medication (3 dogs), continence maintained with phenylpropanolamine (2 dogs), and persistent incontinence despite phenylpropanolamine administration (4 dogs). After surgical repair of ectopic ureters, 2 of 9 (22%) dogs were continent without medication, and 2 (22%) maintained continence with phenylpropanolamine treatment. Various degrees of incontinence persisted in 5 of 9 (56%) dogs, 4 of which had urethral incompetence that had been documented as poorly responsive to phenylpropanolamine administration prior to surgery. Predicted outcomes were consistent with actual outcomes in 8 of 9 (89%) dogs, with predictions of incontinence proving accurate in 4 of 4 (100%) dogs and predictions of continence proving accurate in 4 of 5 (80%) dogs. Urodynamic assessment of dogs with ectopic ureters appears to be valuable for identifying concurrent functional abnormalities of the urinary bladder and urethra and for predicting postoperative outcome.

Adult respiratory distress syndrome in a dog with necrotizing pancreatitis

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Lupus anticoagulant in patients with peripheral vascular disease: a prospective study

OBJECTIVE

To assess the incidence of lupus anticoagulant (LAC) in patients with peripheral vascular disease.

DESIGN

Prospective clinical study.

SETTING

University Hospital.

MATERIALS

20 patients with claudication (group 2), 20 patients with critical ischaemia (group 3) and 20 patients prior to elective abdominal aortic aneurysm surgery (group 4) were compared to 20 general surgical controls (group 1).

CHIEF OUTCOME MEASURES

Venous blood samples for coagulation assay.

MAIN RESULTS

Positive results for LAC by the Dilute Russell's viper venom time (DRVVT) with the platelet neutralisation procedure were present in 26 out of 60 vascular patients compared with none of the 20 general surgical controls. The three vascular groups showed a similar prevalence of LAC and this differed significantly from that in the control group (chi 2 = 10.94, p = 0.0009). Of the 26 positive results only three were associated with an abnormal activated partial thromboplastin time (APTT), which has previously been used as a marker for the presence of LAC activity. Fibrinogen levels were raised in seven of 20 patients in group 2 but were normal in the remaining vascular groups (p = 0.001). The mean factor VII level (124.1 units dl-1) in group 2 was higher than the mean of the remaining vascular patients (109.3 units dl-1, p < 0.05).

CONCLUSIONS

The high prevalence of LAC in patients with peripheral vascular disease and the associated increased risk of early graft thrombosis may justify routine testing by DRVVT prior to reconstructive vascular surgery. Treatment of these patients with antiplatelet agents or formal anticoagulation perioperatively should be considered.

Inappropriate neutrophil activation in venous disease

Neutrophil oxygen radical production was studied in 18 limbs with class 2 or 3 venous disease and compared with that of nine normal limbs. Neutrophils were isolated from arm and leg venous samples. Free radical production was determined using chemiluminescence after stimulation with the chemotactic peptide formyl-methionyl-leucyl-phenylalanine (FMLP) or the ester phorbol myristate acetate (PMA). The ratio of leg to arm luminescence was greater after FMLP stimulation in patients with venous disease (median 1.52 (95 per cent confidence interval (c.i.) 1.27-2.60)) than in controls (median 0.97 (95 per cent c.i. 0.70-1.12); P < 0.01). These changes were not observed with PMA (venous disease 1.16 (95 per cent c.i. 1.05-1.40); controls 0.95 (95 per cent c.i. 0.78-1.24)). There were fewer FMLP receptors on activated leg neutrophils (median 20.19 (95 per cent c.i. 3.58-51.42) fluorescence units) than arm neutrophils (median 36.03 (95 per cent c.i. 13.00-65.28) fluorescence units; P < 0.05), indicating an amplification of signal transduction. Intracellular calcium imaging demonstrated a larger release of calcium after stimulation of leg neutrophils (median 25.0 per cent (95 per cent c.i. 15.7-43.9 per cent)) compared with neutrophils from the arm (median 8.0 per cent (95 per cent c.i. 5.6-16.1 per cent); P = 0.04), demonstrating calcium-dependent activation. Neutrophils in patients with chronic venous disease inappropriately produce more oxygen free radical as a result of amplification of a calcium-dependent signal pathway.

Intravenous digital subtraction angiography versus computed tomography in the assessment of abdominal aortic aneurysm

Results of preoperative investigation of 127 patients who underwent elective aortic aneurysm repair during a 3-year period were examined and compared with findings at operation. The accuracy of preoperative computed tomography (CT) and intravenous digital subtraction angiography (DSA) in assessing proximal and distal aneurysm extent was compared. From a total of 118 CT scans, ten of 12 suprarenal aneurysms were correctly predicted, with 11 false positives (positive predictive value 48 per cent, sensitivity 83 per cent, specificity 90 per cent). After 103 DSA investigations, six of ten suprarenal aneurysms were correctly predicted with one false positive (positive predictive value 86 per cent, sensitivity 60 per cent, specificity 99 per cent). Using CT, 30 of 54 aneurysmal iliac arteries were correctly diagnosed with 20 false positives (positive predictive value 60 per cent, sensitivity 56 per cent, specificity 88 per cent). Thirty-six of 48 aneurysmal iliac arteries were diagnosed correctly using DSA, with 32 false positives (positive predictive value 53 per cent, sensitivity 75 per cent, specificity 79 per cent). Intravenous DSA also provided useful information about renal and peripheral occlusive disease. Both investigations have their own specific limitations; clinicians should be aware of these when ordering and interpreting them.

Acute intestinal ischaemia: options in surgical management

Seven patients (mean age 67 years, range 52-82 years) presented with acute intestinal ischaemia over a 4-year period. Massive bowel resection was performed in all patients. Exteriorisation and secondary restoration of intestinal continuity was employed in four patients. In two patients a primary anastomosis was performed at the time of resection and one patient underwent a 'second-look' procedure. Massive bowel resection and exteriorisation allows direct observation of stoma viability, avoids the risk of anastomotic breakdown and should be considered in all but moribund patients with acute intestinal ischaemia. In elderly patients resection and primary anastomosis may be an alternative option.

Adenocarcinoma of the middle ear with osteolysis of the tympanic bulla in a cat

Peripheral vestibular disease and lethargy were attributed to an adenocarcinoma in the middle ear of a 10-year-old cat. The tumor was invasive, inducing severe lysis of the tympanic bulla and adjacent temporal bone. Direct invasion to the meninges and brainstem also was observed. Neoplasms of the middle ear are rare in cats, with squamous cell carcinomas reported most commonly, but should be considered as causes of chronic otitis or signs of peripheral vestibular disease.

A specific thromboxane receptor blocking drug, AH23848, reduces platelet deposition on vascular grafts in man

The antithrombotic effect of a specific thromboxane A2 receptor blocking drug, AH23848, on radio-labelled platelet deposition in mature Dacron aorto-bifemoral grafts has been evaluated in patients. Thirty patients were randomly allocated to AH23848 70 mg, aspirin 300 mg plus dipyridamole 75 mg or placebo 8-hourly for 9 days. AH23848 inhibited platelet aggregation induced by the thromboxane A2 mimetic U-46619; no such effect was observed with aspirin plus dipyridamole. 111In-platelet uptake was measured as the thrombogenicity index (TI) which is a measure of the daily rate of accumulation of platelets by the graft. The mean (s.e. mean) value of 0.193 (0.029) on placebo was significantly reduced to 0.115 (0.022) by AH23848 (p less than 0.05) but only to 0.175 (0.028) by aspirin plus dipyridamole. There was no difference in mean platelet life span between the three treatment groups. The pronounced antithrombotic effect of AH23848 implicates thromboxane A2 in the process of platelet deposition in arterial prostheses and demonstrates the considerable promise of thromboxane receptor blocking drugs as antithrombotic therapy.

Pulmonary microembolization in experimental aortic surgery

Pulmonary dysfunction frequently follows major surgery and has many features identical to "shock lung'. A porcine model of aortic surgery is described in which 111In-labelled platelet kinetics were related to subsequent pulmonary function. In 14 pigs, standardized aortic surgery resulted in reproducible shock and a 50 per cent mortality at 3 days. Cardiac output fell from 2.3 +/- 0.2 to 1.0 +/- 0.1 litres min-1 following removal of the aortic clamp and mean platelet and leucocyte counts fell from 437 +/- 48 to 252 +/- 39 x 10(9) litres-1 and 21.7 +/- 1.5 to 12.9 +/- 1.2 x 10(9) litres-1 respectively (P less than 0.01). Aggregate levels in inferior vena caval blood were maximal at this time and radiolabelled platelets accumulated in the lung with a rise in pulmonary vascular resistance. Alveolar-arterial oxygen difference subsequently increased from initial values of 13.7 +/- 2.0 to 23.4 +/- 3.5 mmHg (P less than 0.01) following resuscitation and to 32.5 +/- 3.4 mmHg at 3 days following surgery (P less than 0.01). This clear sequence suggests that pulmonary platelet microembolization occurs during surgical shock and may be responsible for subsequent pulmonary dysfunction.

An evaluation of Dacron prostheses in the relief of jaundice due to malignant obstruction

In 26 patients, relief of obstructive jaundice due to malignancy has been effected by inserting a Dacron biliary-enteric prosthesis. All cases were considered unsuitable for conventional biliary bypass procedures. The hospital mortality was 27% and mean survival of those patients discharged was 8 months. Insertion of a Dacron prosthesis may prove an alternative to percutaneous biliary stenting in selected patients with neoplastic biliary obstruction.

Platelet kinetics following carotid endarterectomy: the effect of aspirin and patch angioplasty

Platelet deposition on the subintimal surface of the arterial wall following endarterectomy has been implicated in the development of postoperative thrombosis, intimal hyperplasia and may be important in recurrent stenosis. Autologous radiolabelled platelet deposition has been measured in 51 patients following carotid endarterectomy. The effect of platelet inhibitory drugs and patch angioplasty on early postoperative platelet accumulation at the site of endarterectomy has been investigated. In patients undergoing direct suture of the arteriotomy, platelet deposition measured as the Carotid Uptake Ratio was significantly reduced from 1.44 +/- 0.03 to 1.11 +/- 0.35 in those receiving aspirin and dipyridamole (P less than 0.002). Carotid Uptake Ratio was greater following patch angioplasty at 1.41 +/- 0.07 when compared to 1.14 +/- 0.07 with direct suture of the arteriotomy (P less than 0.002).

Radiolabeled platelets in detecting the source of recurrent pulmonary emboli--a case report

Multiple pulmonary emboli are recognized to be the cause of progressive pulmonary failure. In these patients, the source of emboli may be difficult to detect, even by venography. The authors describe the use of autologous Indium 111-labeled platelets to locate the origin in a patient with progressing right heart failure.

Effect of the cyclo-oxygenase inhibitor indobufen on platelet accumulation in prosthetic vascular grafts

An in vivo method of measuring thrombus deposition and pseudo-intimal thickening in prosthetic arterial grafts in an animal model is described. The effect of indobufen, a new cyclo-oxygenase inhibitor, was evaluated and compared to aspirin plus dipyridamole and placebo in 24 greyhounds. Luminal platelet accumulation expressed as thrombogenicity index was 0.33 +/- 0.07 in the placebo group. This was significantly reduced to 0.14 +/- 0.01 by indobufen (P less than 0.05). The reduction to 0.19 +/- 0.04 by aspirin plus dipyridamole failed to achieve statistical significance. Pseudointimal thickness when measured 28 days after implacement was significantly reduced to 21.4 +/- 10.6 per cent by indobufen (P less than 0.01) and 29.4 +/- 10.6 per cent by aspirin plus dipyridamole (P less than 0.02) compared to 75 +/- 10 per cent found in the placebo group. This prosthetic graft model has considerable advantages in the evaluation of potential platelet inhibitory drugs for use in vascular surgery.

Carcinoma of the lung presenting with digital ischaemia

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Colonic haemorrhage: a technique for rapid intra-operative bowel preparation and colonoscopy

We describe a new technique of operative orthograde colonic washout followed by colonoscopy for use in patients with severe colonic haemorrhage. We report its use in four patients in whom the exact source of bleeding was localized and treated. In two of these cases a policy of 'blind' hemicolectomy would have been incorrect. The technique is simple and safe, and we advocate its use during laparotomy for major colonic haemorrhage.

Strategy for lymph node biopsy in homosexual men suspected of having LAV/HTLV-III related disease

Since January 1985 we have changed our policy regarding lymph node biopsy in male homosexuals presenting with lymphadenopathy. Before that date all such patients underwent biopsy if there was no apparent cause. We no longer perform biopsy in male homosexuals presenting with uncomplicated persistent generalized lymphadenopathy (enlargement to more than 1 cm of lymph nodes in more than one extra-inguinal site for more than 3 months with no apparent cause) provided that the patient is positive for the antibody to lymphadenopathy associated virus/human T-lymphotropic virus type III. Such a policy should reduce the need for open biopsy procedures in this group of patients.

The effects of thromboxane antagonism on the transit time of platelets through the spleen

The spleen is well-known as a site for platelet pooling, although the mechanisms controlling intrasplenic platelet transit are essentially unknown. We tested the possibility that thromboxane A2 might be involved in this control by measuring intrasplenic platelet transit time in 10 subjects receiving a specific thromboxane A2 receptor antagonist (AH23848B; 70 mg; Glaxo Group Research Ltd), in 10 receiving aspirin (300 mg) plus dipyridamole (75 mg), and in 9 receiving placebo. All doses were administered 3 times daily commencing 4 days prior to transit time measurement. Mean intrasplenic platelet transit time was measured by monitoring the kinetics of equilibration of 111In radiolabelled platelets between blood and spleen following intravenous injection. There was no difference between the mean transit time in the 3 groups of subjects, lending no support to the hypothesis that thromboxane A2 is involved in the control of platelet traffic through the spleen.