Search PubMed⌕ Search

Biomedical subjects

P L Allan

Publications and source records attributed to P L Allan.

At least 19 recordsLinked to original sources
PubMed2000

Thrombosis in a duplicated superficial femoral vein in a patient with haemophilia A.

Venous thrombosis is a very rare occurrence in patients with haemophilia A. We report the case of a haemophiliac in whom initially a calf haematoma was suspected, but neither this nor deep venous thrombosis (DVT) could be confirmed on ultrasound scanning. Subsequently, a high segment venous thrombosis was diagnosed by venography in a portion of a duplicated superficial femoral vein. Treatment with factor VIII (FVIII) and low molecular weight heparin led to a successful resolution. The only other case we have been able to find in the literature occurred during FVIII replacement therapy, which was not the situation with our patient.

Adult↗
PubMed2000

Patterns of reflux and severity of varicose veins in the general population--Edinburgh Vein Study.

OBJECTIVES: several studies have used duplex ultrasound to assess valvular incompetence in symptomatic patients. This cross-sectional survey was performed to determine, for the first time in a general population sample, the relationship between trunk varices and the presence of reflux in lower limb venous segments. MATERIALS AND METHODS: 1238 subjects (554 male, 684 female), aged 18-64 years, were randomly selected. The presence and severity of any trunk varices was assessed and classified into Grades 1-3; hyphenweb and reticular varices were noted. The presence or absence of reflux > or = 0.5 s in five deep and three superficial venous segments in each leg was assessed using duplex ultrasound. RESULTS: the prevalence of reflux increased in both superficial and deep segments with more severe grades of trunk varices (p< or = 0.01), except the upper SFV in women. Fifteen per cent of females showed reflux confined to the superficial system, compared with 9% of males (p< or = 0.001); 22% of males showed deep reflux, compared with 11% of females (p < or = 0.001). 71% of men and 48% of women with Grade 2-3 trunk varices had mixed deep and superficial reflux. Above-knee popliteal segments had a higher prevalence of reflux than lower SFV segments in all groups. There was no consistent relationship between the presence of hyphenweb or reticular varices and deep or superficial reflux. CONCLUSION: segmental venous reflux can be detected in the deep and superficial leg veins of subjects without trunk varices, but superficial and mixed reflux are increasingly found in subjects with more severe varices.

Adolescent↗
PubMed2000

The relationship between the number, competence, and diameter of medial calf perforating veins and the clinical status in healthy subjects and patients with lower-limb venous disease.

PURPOSE: The role of medial calf perforating veins in the pathogenesis of the skin changes of chronic venous insufficiency (CVI) remains controversial. This study examined the relationship between abnormal medial calf perforating vein structure and function and the clinical severity of CVI. METHODS: Duplex ultrasound was used as a means of determining the number, flow characteristics, and diameter of medial calf perforating veins, and the presence of deep and superficial main stem reflux or occlusion in 50 limbs with no clinical or duplex evidence of venous disease (clinical, etiological, anatomical, and pathological grade [CEAP] 0), 95 limbs with varicose veins only (CEAP 2/3), 58 limbs affected by lipodermatosclerosis but not ulcer (CEAP 4), and 108 limbs affected by healed or open venous ulcer (CEAP 5/6). RESULTS: The proportion of limbs in which any perforating veins and incompetent perforating veins (IPVs) were demonstrated increased significantly with deteriorating clinical status (CEAP 0, 88% and 6%; CEAP 2/3, 95% and 52%; CEAP 4, 98% and 83%; and CEAP 5/6, 98% and 90%, respectively). The total number of perforators, the total number of IPVs, and the median diameters of perforators increased with deteriorating grade (CEAP 0 median diameter, 2 mm [interquartile range, 1 to 3 mm]; CEAP 2/3 median diameter, 3 mm [interquartile range, 2 to 4 mm]; CEAP 4 median diameter, 4 mm [interquartile range, 3 to 5 mm]; and CEAP 5/6 median diameter, 4 mm [interquartile range, 3 to 5 mm]). CONCLUSION: The deteriorating CEAP grade of CVI is associated with an increase in the number and diameter of medial calf perforating veins, particularly those permitting bidirectional flow.

Adult↗
PubMed1999

Laparoscopy with laparoscopic ultrasonography in the TNM staging of pancreatic carcinoma.

A prospective study was performed comparing laparoscopy with laparoscopic ultrasonography (LapUS), transabdominal ultrasonography (USS), computed tomography (CT), and selective visceral angiography with portal phase venography (SVA) for the assessment of resectability in 50 patients with pancreatic or periampullary cancer. The results were stratified by TNM stages. Tumor unresectability was demonstrated in 36 patients (72%). The sensitivity of LapUS for demonstrating the index lesion was 96%. Laparoscopic ultrasonography failed to predict factors precluding resection by T stage in six patients, and there were no significant differences in the ability of any modality to predict local resectability (predictive value 58-73%). Laparoscopic ultrasonography did not overestimate T stage and was significantly more specific for assessing unresectability compared with USS (100% vs. 64%, p<0.05) and CT (100% vs. 47%, p<0.005). No imaging investigation was able to assess the N stage accurately. Metastases were confirmed in 16 patients (32%), with LapUS proving significantly more sensitive than USS (94% vs. 29%, p<0.001) and CT (94% vs. 33%, p<0.005). The addition of LapUS to the laparoscopic examination did not change the M stage in any patient, as all metastases were superficially located. Laparoscopy with LapUS was the most reliable method for assessing overall tumour resectability and was significantly more predictive than CT (97% vs. 79%, p<0.005). These results confirm that laparoscopy is indispensable for detecting occult intraabdominal metastases. LapUS reliably predicts tumor unresectability, offsetting the tendency of USS and CT to overestimate T stage. Methods of accurate N staging remain elusive, and the use of routine SVA is not justified.

Adult↗
PubMed1998

Blood viscosity and elevated carotid intima-media thickness in men and women: the Edinburgh Artery Study.

BACKGROUND: Several hemostatic and rheological factors have been associated with incident cardiovascular events. However, there have been no reports on the relationship of rheological factors with early atherosclerosis and very few on hemostatic factors. We therefore studied the relationship between these factors and carotid intima-media thickness (IMT). METHODS AND RESULTS: The Edinburgh Artery Study measured fibrinogen, tissue plasminogen activator (tPA), fibrin D-dimer, von Willebrand factor (vWF), blood and plasma viscosities, and hematocrit as part of its baseline examination during 1988-1989. At the 5-year follow-up, valid measurements of IMT had been recorded in 1106 men and women 60 to 80 years old. In men, blood viscosity (P< or =.001) and its major determinants, plasma viscosity, fibrinogen (both P< or =.01), and hematocrit (P< or =.05), were all linearly related to IMT. Furthermore, blood viscosity, fibrinogen (both P< or =.01), and plasma viscosity (P< or =.05) remained significantly associated on multivariate analysis. Correcting blood viscosity to a standard hematocrit of 45% had little effect on its association. In men, there was a significantly increased risk of having an IMT above versus below the upper quartile of its distribution (1.05 mm) for SD increases in blood viscosity (P< or =.01), fibrinogen, corrected blood viscosity, and plasma viscosity (all P< or =.05). With the exception of plasma viscosity, these risks were unaffected by adjustment for other common cardiovascular risk factors. No significant associations were found between any of the hemorheological factors and IMT in women or for tPA, fibrin D-dimer, or vWF in either sex. CONCLUSIONS: These findings suggest that in men, blood viscosity and its major determinants are associated not only with incident cardiovascular events but also with the early stages of atherosclerosis. This may be one explanation for the link between rheological factors and events.

Age Factors↗
PubMed1998

Prevalence of venous reflux in the general population on duplex scanning: the Edinburgh vein study.

PURPOSE: The prevalence of reflux in the deep and superficial venous systems in the Edinburgh population and the relationship between patterns of reflux and the presence of venous disease on clinical examination were studied. METHODS: A cross-sectional survey was done on men and women ranging in age from 18 to 64 years, randomly selected from 12 general practices. The presence of varicose veins and chronic venous insufficiency was noted on clinical examination, as was the duration of venous reflux by means of duplex scanning in 8 vein segments on each leg. Results were compared using cut-off points for reflux duration (RD) of 0.5 seconds or more (RD >/= 0.5) and more than 1.0 second (RD > 1.0) to define reflux. RESULTS: There were 1566 study participants, 867 women and 699 men. The prevalence of reflux was similar in the right and left legs. The proportion of participants with reflux was highest in the lower thigh long saphenous vein (LSV) segment (18.6% in the right leg and 17.5% in the left leg for RD >/= 0.5), followed by the above knee popliteal segments (12.3% in the right leg and 11.0% in the left leg for RD >/= 0.5), the below knee popliteal (11.3% in the right leg and 9.5% in the left leg for RD >/= 0.5), upper LSV (10.0% in the right leg and 10.8% in the left leg for RD >/= 0.5) segments, the common femoral vein segments (7.8% in the right leg and 8.0% in the left leg for RD >/= 0.5), the lower superficial femoral vein (SFV) segments (6.6% in the right leg and 6.4% in the left leg for RD >/= 0.5), and the upper SFV (5.2% in the right leg and 4.7% in the left leg for RD >/= 0.5) and short saphenous vein (SSV) (4.6% in the right leg and 5.6% in the left leg for an RD >/= 0.5) segments. In the superficial vein segments, there was little difference in the occurrence of reflux whether RD >/= 0.5 or RD > 1.0 was used; but in the different deep vein segments, the prevalence of reflux was 2 to 4 times greater for RD >/= 0.5 rather than RD > 1.0. Men had a higher prevalence of reflux in the deep vein segments than women, reaching statistical significance (P </=.01) in 4 of 5 segments for RD >/= 0.5. In general, the prevalence of reflux increased with age. Those with "venous disease" had a significantly higher prevalence of reflux in all vein segments than those with "no disease" (P </=.001). CONCLUSION: The prevalence of venous reflux in the general population was related to the presence of "venous disease," although it was also present in those without clinically apparent disease. There was a higher prevalence of reflux in the deep veins in men than the deep veins in women. Follow-up study of the population will determine the extent to which reflux is a predictor of future disease and complications.

Adolescent↗
PubMed1998

Saphenous surgery does not correct perforator incompetence in the presence of deep venous reflux.

PURPOSE: To determine which patients require subfascial endoscopic perforator surgery (SEPS) in addition to saphenous surgery to correct pathologic outward flow within incompetent medial calf perforating veins (IPVs). METHODS: Sixty-two limbs of 47 patients undergoing sapheno-femoral ligation, stripping of the long saphenous vein in the thigh, and multiple phlebectomies (n = 51), sapheno-popliteal ligation and multiple phlebectomies (n = 10), or both (n = 1) were examined with color flow duplex ultrasound scan immediately before and a median of 14 weeks (range, 6 to 26 weeks) after the operations. Indications for surgery were varicose veins (n = 47, Clinical, Etiologic, Anatomic, Pathophysiologic grades C2&3), skin changes (n = 5, C4), and ulceration (n = 10, C5). RESULTS: Surgery resulted in a significant reduction in the total number of limbs in which IPVs were imaged (40/62 or 65% preoperatively vs 23/62 or 37% postoperatively, P <.01, chi2 test), a significant reduction in the proportion of perforators imaged that were incompetent (68/130 or 52% preoperatively vs 34/120 or 28% postoperatively, P <.01, chi2 test), and a reduction in median IPV diameter (4 mm, with a range of 1 to 11 mm preoperatively, vs 3, with a range of 1 to 8 mm postoperatively, P <.01, Mann-Whitney U test). IPVs remained in 8 of 41 (20%) limbs in which main stem reflux was abolished, compared with 15 of 21 (72%) limbs in which superficial or deep reflux remained (P <.01, chi2 test). CONCLUSION: Eradication of main stem saphenous reflux corrects IPV reflux in most cases in which reflux is confined to the superficial system. However, in patients with superficial reflux that persists postoperatively, or when there is coexistent deep venous reflux, saphenous surgery alone fails to correct IPVs reflux. In these circumstances, the only way of reliably correcting pathologic outward flow in medial calf perforating veins is to perform SEPS.

Adult↗
PubMed1998

Popliteal vein reflux reduces the healing of chronic venous ulcer.

BACKGROUND: The relationship between deep and superficial venous reflux and healing of venous ulceration by non-operative compression therapy has not been studied previously. METHODS: A total of 155 patients with chronic venous ulcers underwent duplex ultrasonography before treatment with compression bandaging at a hospital-based venous clinic. RESULTS: At 24 weeks, 104 (67 per cent) of ulcers had healed. There was no significant difference in the pattern of either deep or superficial venous reflux between healed and non-healed ulcers except with respect to the popliteal vein. In healed ulcers, 39 scans (38 per cent) indicated competence of the above-knee popliteal vein compared with five (10 per cent) in the non-healing group (P < 0.001, chi 2 test). Similarly, 43 scans (42 per cent) showed below-knee popliteal vein competence in the healed ulcers compared with only five (10 per cent) performed in legs remaining ulcerated (P < 0.001, chi 2 test). CONCLUSION: Popliteal vein incompetence is an indicator of poor response to compression therapy for venous ulceration.

Adult↗
PubMed1997

Laparoscopic ultrasonography for staging gastroesophageal cancer.

BACKGROUND: TNM staging of gastroesophageal cancer is improved by the use of laparoscopy for the detection of occult metastases and endoscopic ultrasonography for T and possibly N staging. Laparoscopic ultrasonography may combine the strengths of both of these techniques. The purpose of this study was to compare TNM staging by means of laparoscopic ultrasonography (Lap US), laparoscopy, and conventional computed tomography (CT). METHODS: TNM stage was determined by using Lap US, laparoscopy, and CT scanning in 26 surgical candidates with gastric or esophageal cancer in a blinded fashion. CT scans were also reviewed separately by an expert radiologist. Validation of findings was by means of final pathologic examination. RESULTS: Resectability for potential cure was determined by means of Lap US with a sensitivity of 100% and a specificity of 91% versus 100% and 73% for laparoscopy and 75% and 60% for CT, respectively. Overall TNM staging was 82% accurate for Lap US versus 67% for laparoscopy and 47% for CT (chi-squared, 8.64, p < 0.005, and 10.4, p < 0.005, respectively). Accuracies for Lap US versus laparoscopy versus CT for N stage were 92% versus 84% versus 70%, respectively, for T stage were 92% versus 42% versus 60%, respectively, and for M stage were 89% versus 44% versus 62%, respectively. CONCLUSIONS: T and N staging by Lap US were comparable to published results for endoscopic ultrasonography, and overall TNM staging was better. Lap US may provide the optimal preoperative staging for gastric cancer and has the potential to complement endoscopic ultrasonography in staging esophageal cancer.

Adult↗
PubMed1997

Smoking, atherosclerosis and risk of abdominal aortic aneurysm.

AIMS: The role of cardiovascular risk factors and atherosclerosis in the aetiology of abdominal aortic aneurysms is not well understood. The aim of this study was to determine the association between atherosclerosis and aortic aneurysm in the general population and the extent to which cardiovascular risk factors might increase the risk of aneurysm independently of an effect on atherosclerotic disease. METHODS AND RESULTS: In the Edinburgh Artery Study, 1592 men and women aged 55-74 years were followed prospectively over a period of 5 years. Forty subjects were identified as having an abdominal aortic aneurysm and, for each, five controls were randomly selected. Case showed a higher prevalence of cardiovascular disease (P < or = 0.001) and had a lower ankle brachial pressure index (P < or = 0.01). Current and recent ex-cigarette smokers had an increased risk of aortic aneurysm compared with long time ex-smokers and never smokers (odds ratio 3.08, 95% CI 1.53 to 6.21). Adjustment for concurrent atherosclerotic disease reduced the odds ratio to 2.63 (95% CI 1.26 to 5.45). The risk of aortic aneurysm was not related to elevation in diastolic blood pressure or in serum cholesterol. CONCLUSIONS: These findings indicate that atherosclerotic disease is associated with risk of aortic aneurysm in the general population. In addition, cigarette smoking appears to have a direct effect on the risk of aortic aneurysm which is independent of atherosclerosis.

Aged↗
PubMed1997

Relationship between carotid intima-media thickness and symptomatic and asymptomatic peripheral arterial disease. The Edinburgh Artery Study.

BACKGROUND AND PURPOSE: Ultrasonic evaluation of intimamedia thickness (IMT) is one method of assessing the development of early atherosclerosis. This report describes the distribution of IMT within the general population and is one of the first to investigate its association with noninvasively assessed symptomatic and asymptomatic peripheral arterial disease. METHODS: Ultrasonic evaluation of IMT was included in the 5-year follow-up examination of participants of the Edinburgh Artery Study. Valid readings of IMT were recorded in 1106 subjects aged 60 to 80 years, and the maximum from the right and left sides of the neck was used in the analysis. Existing symptomatic and asymptomatic peripheral arterial disease and coronary heart disease were also assessed at follow-up using previously validated noninvasive techniques. RESULTS: IMT increased continuously with age (P < or = .01), and its distribution was positively skewed in both sexes. The results suggest that levels of atherosclerotic development in the common carotid artery are 5 to 10 years more advanced in men than in women. In this population, the overall prevalence of moderate to severe disease was very low (only 1.2% of study participants had IMT values > 2 mm). The presence of symptomatic (intermittent claudication) or asymptomatic (ankle brachial pressure index < or = 0.9) peripheral arterial disease was significantly associated with increased IMT (P < or = .05). CONCLUSIONS: Although the prevalence of advanced atherosclerosis was very low, small changes in IMT were associated with clinically significant development of atherosclerosis in the peripheral arteries. However, further longitudinal studies are needed that standardize measurement techniques and would allow accurate comparisons across studies.

Adult↗
PubMed1996

Comparison of venous reflux in the affected and non-affected leg in patients with unilateral venous ulceration.

In 54 patients with unilateral leg ulceration of purely venous aetiology the only difference in venous reflux between affected and non-affected legs was with respect to the popliteal and crural veins. Deep and superficial venous reflux is common in legs without the skin changes typical of chronic venous insufficiency. The significance of venous reflux in an ulcerated leg cannot therefore be determined without reference to the contralateral, clinically normal, limb. Surgery should be directed at correcting reflux present in the ulcerated limb but not in the unaffected limb. In a minority of patients this entails superficial venous surgery alone, but in the majority such an approach would, ideally, entail correction of deep venous incompetence.

Aged↗
PubMed1996

Growth rate of infrarenal aortic aneurysms.

OBJECTIVE: To delineate the natural history of infrarenal aortic aneurysms with respect to growth rate. METHODS: A referral based series of 233 patients with abdominal aortic aneurysm was serially assessed by abdominal ultrasound. RESULTS: The mean age was 71 years and the median follow up 26 months (range 6-146). The mean growth rate of the series was 3.2mm/year. Division of the initial size into those less than 41 mm (128 patients), between 41-60 mm (92 patients) and those above 60 mm (13 patients) in AP diameter showed mean growth rates per year were 2.6 mm/year, 4.1 mm/year and 6.5 mm/year. Examination of the relationship between aneurysm size and subsequent growth rate over the whole study period revealed a rank correlation of 0.19 (p = 0.002). Aneurysms were also observed to expand at an erratic rate both in terms of time and size. CONCLUSIONS: When the initial decision is to observe the patient, serial ultrasound examinations facilitate later judgements on the balance of risks in relation to surgical treatment.

Adult↗
PubMed1996

Spiral laminar flow in vivo.

1. Blood flow patterns are poorly understood despite their impact on arterial disease. There have been few measurements in vivo of the three-dimensional blood flow patterns; we present the results of such studies using a new non-invasive in-vivo method of examining biplanar arterial blood flow patterns. 2. Multiple colour Doppler ultrasound directional velocity images were obtained at two different beam target angles from the artery in the plane perpendicular to its axis. Ensemble average images were constructed; the absolute velocity and direction were calculated by compounding the left and right averaged images. Simple directional, non-directional velocity and vector maps were constructed. 3. Flow patterns were sampled in 11 healthy male volunteers at four points of the pulse cycle; peak systole, systolic downswing, diastolic reverse flow and diastolic forward flow and at three sites; the right common and distal superficial femoral and the left common femoral arteries. 4. Stable rotational flow was observed in all subjects, the direction of rotation varying between sides and individuals. 5. There are theoretical advantages to spiral laminar blood flow; the forward-directed, rotationally induced stability and reduction of laterally directed forces may reduce turbulence in the tapering branching arterial tree and at stenoses and have a beneficial effect on mechanisms of endothelial damage and repair.

Blood Flow Velocity↗
PubMed1996

Prospective evaluation of haematological alterations following the transjugular intrahepatic portosystemic stent-shunt (TIPSS).

BACKGROUND: TIPSS is effective in reducing portal hypertension and provides access to the portal system for direct pressure measurements. OBJECTIVE: To assess the incidence and severity of haemolysis and its course following TIPSS, and also to assess changes in spleen size and any relationship to changes in the platelet and white cell count and haemoglobin concentration. DESIGN: A prospective study. MATERIALS AND METHODS: Twenty-three patients undergoing TIPSS with a mean follow-up of 8 months (SE 1.2) were studied. Male-female ratio was 13:10 and the mean age was 53.6 years (SE 1.7). Full blood count, reticulocyte count, serum haptoglobin, urinary haemosiderin, examination of the peripheral blood smear and spleen size (ultrasonography) were measured prior to and 3, 7 and 30 days after TIPSS and 6-monthly thereafter. RESULTS: Seven patients (30.4%) developed haemolysis, which was clinically significant in three (13%). This settled spontaneously within 2 weeks of TIPSS. Portal pressure gradient was reduced from a mean of 21.9 (SE 1.6) to 9.5 (SE 1) mmHg (P < 0.001) and did not change significantly thereafter. Haemoglobin concentration improved significantly from a mean of 89 (SE 16) to 113 (SE 19) g/l (P < 0.05) after TIPSS. Significant changes in spleen size and platelet count occurred, with a reduction in the former from 16.9 (SE 1.1) to 13.7 cm (SE 2.4) (P < 0.01) and an increase in the latter from 85.9 (SE 8.4) to 135.3 x 10(9)/l (SE 16.8) (P < 0.01). No significant correlations were found between the changes in the portal pressure gradient, spleen size and platelet count. There was no significant change in the white cell count. CONCLUSION: Transient significant haemolysis occurs in about 13% of patients following TIPSS. TIPSS is useful for reducing splenomegaly and improving thrombocytopenia and haemoglobin. There is no correlation between the changes in portal pressure gradient, spleen size and platelet count.

Anemia, Hemolytic↗
PubMed1996

Measurement of spleen size and its relation to hypersplenism and portal hemodynamics in portal hypertension due to hepatic cirrhosis.

AIMS: Splenomegaly is common in portal hypertension due to hepatic cirrhosis, but there are little data comparing different methods of spleen measurement. We have compared ultrasound with radionuclide imaging in measuring splenomegaly. The relation of splenomegaly to hypersplenism and portal hemodynamic factors was also studied. RESULTS: Ultrasound and radionuclide measures of spleen volume gave comparable results (r = 0.95, p < 0.0001). Phagocytic activity of the spleen measured by radionuclide uptake increased as the volume of the spleen increased (r = 0.46, p < 0.03) but was not related to diminishing liver phagocytic activity. Spleen volume was correlated negatively with leukocyte counts (r = 0.43, p < 0.05) but not with hemoglobin or platelet counts. Spleen radionuclide uptake was negatively correlated with hemoglobin (r = 0.48, p < 0.04) and leukocyte counts (r = 0.46, p < 0.04) but not with platelet counts. Spleen volume was related to portal vein cross-sectional area (r = 0.91, p < 0.0001) and portal vein blood flow volume (r = 0.57, p < 0.008) but not to portal vein blood flow velocity, portal pressure gradient, or azygos blood flow. CONCLUSIONS: Spleen size measured by ultrasonography and radionuclide studies gives comparable results. Spleen phagocytic activity in cirrhosis increases as the spleen enlarges but not in relation to decreased hepatic phagocytic activity. Spleen phagocytic activity probably contributes to anemia and leukopenia in the splenomegaly of cirrhosis, but other factors must contribute to thrombocytopenia. Portal hemodynamics are probably important in the splenomegaly, but the interrelation is complex.

Female↗