Computer analysis of ultrasonic plaque echolucency in identifying high risk carotid bifurcation lesions

OBJECTIVES

to confirm that plaque echogenicity evaluated by computer analysis, as suggested by preliminary studies, can identify plaques associated with a high incidence of strokes.

MATERIALS AND METHODS

a series of 96 patients with carotid stenosis in the range of 50-99% were studied retrospectively (41 with TIAs and 55 asymptomatic). Carotid plaque echogenicity was evaluated using a computerised measurement of the median grey scale value (GSM). All patients had a CT brain scan to determine the presence of infarction in the carotid territory.

RESULTS

the incidence of ipsilateral brain CT infarctions was 16% in the asymptomatic and 32% in the symptomatic plaques (p =0.076). It was 20% for <70% stenosis and 25% for >70% stenosis (p =0.52). It was 9% for plaques which had a GSM >50 and 40% in those with GSM <50 (p <0.001) with a relative risk of 4.6 (95% CI 1.8 to 11.6).

CONCLUSIONS

the results confirm that computer analysis of plaque echogenicity is better than the degree of stenosis in identifying plaques associated with an increased incidence of CT brain-scan infarction and consequently useful for identifying individuals at high risk of stroke. What is required is a form of image standardisation in order to apply this method to natural history studies with stroke as the endpoint.

Carotid plaque, intima media thickness, cardiovascular risk factors, and prevalent cardiovascular disease in men and women: the British Regional Heart Study

BACKGROUND AND PURPOSE

B-mode ultrasound is a noninvasive method of examining the walls of peripheral arteries and provides measures of the intima-media thickness (IMT) at various sites (common carotid artery, bifurcation, internal carotid artery) and of plaques that may indicate early presymptomatic disease. The reported associations between cardiovascular risk factors, clinical disease, IMT, and plaques are inconsistent. We sought to clarify these relationships in a large, representative sample of men and women living in 2 British towns.

METHODS

The study was performed during 1996 in 2 towns (Dewsbury and Maidstone) of the British Regional Heart Study that have an approximately 2-fold difference in coronary heart disease risk. The male participants were drawn from the British Regional Heart Study and were recruited in 1978-1980 and form part of a national cohort study of 7735 men. A random sample of women of similar age to the men (55 to 77 years) was also selected from the age-sex register of the general practices used in the original survey. A wide range of data on social, lifestyle, and physiological factors, cardiovascular disease symptoms, and diagnoses was collected. Measures of right and left common carotid IMT (IMTcca) and bifurcation IMT (IMTbif) were made, and the arteries were examined for plaques 1.5 cm above and below the flow divider.

RESULTS

Totals of 425 men and 375 women were surveyed (mean age, 66 years; range, 56 to 77 years). The mean (SD) IMTcca observed were 0. 84 (0.21) and 0.75 (0.16) mm for men and women, respectively. The mean (SD) IMTbif were 1.69 (0.61) and 1.50 (0.77) mm for men and women, respectively. The correlation between IMTcca and IMTbif was similar in men (r=0.36) and women (r=0.38). There were no differences in mean IMTcca or IMTbif between the 2 towns. Carotid plaques were very common, affecting 57% (n=239) of men and 58% (n=211) of women. Severe carotid plaques with flow disturbance were rare, affecting 9 men (2%) and 6 women (1.6%). Plaques increased in prevalence with age, affecting 49% men and 39% of women aged <60 years and 65% and 75% of men and women, respectively, aged >70 years. Plaques were most common among men in Dewsbury (79% affected) and least common among men in Maidstone (34% affected). IMTcca showed a different pattern of association with cardiovascular risk factors from IMTbif and was associated with age, SBP, and FEV1 but not with social, lifestyle, or other physiological risk factors. IMTbif and carotid plaques were associated with smoking, manual social class, and plasma fibrinogen. IMTbif and carotid plaques were associated with symptoms and diagnoses of cardiovascular diseases. IMTbif associations with cardiovascular risk factors and prevalent cardiovascular disease appeared to be explained by the presence of plaques in regression models and in analyses stratified by plaque status.

CONCLUSIONS

IMTcca, IMTbif, and plaque are correlated with each other but show differing patterns of association with risk factors and prevalent disease. IMTcca is strongly associated with risk factors for stroke and with prevalent stroke, whereas IMTbif and plaque are more directly associated with ischemic heart disease risk factors and prevalent ischemic heart disease. Our analyses suggest that presence of plaque, rather than the thickness of IMTbif, appears to be the major criterion of high risk of disease, but confirmation of these findings in other populations and in prospective studies is required. The association of fibrinogen with plaque appears to be similar to its association with incident cardiovascular disease. Further work elucidating the composition of plaques using ultrasound imaging would be helpful, and more data, analyzed to distinguish plaque from IMTbif and IMTcca, are required to understand the significance of thicker IMT in the absence of plaque.

The edema tester in the evaluation of swollen limbs in venous and lymphatic disease

BACKGROUND

Edema is a common condition in most venous and lymphatic diseases. The ACI edema testers (ET) have been developed to objectively evaluate the presence of edema. Two types of testers have been developed. ET1 is a soft plastic plate (5 x 2 cm) characterised by two parallel protrusions while the ET2 is characterised by two lines of 7 holes.

METHODS

The ETs are applied onto the internal perimalleolar region with the protrusions/holes in contact with the skin. A blood pressure cuff is applied over the area (pressure maintained at 50 mmHg for a period between 1-3 minutes). When the cuff is removed, with the ET1 skin marks are usually just visible in normal limbs (they disappear in a few minutes). We studied 22 normal limbs, 19 with varicose veins, 22 with chronic venous insufficiency, 5 with primary lymphedema and 8 with severe chronic lymphedema.

RESULTS

In limbs with severe edema the whole length of the protrusions is visible; with moderate edema only a part of the protrusions is visible. With the ET2 skin marks are just visible in normal limbs (only the larger holes). Marks disappear in a few minutes in normal limbs while in limbs with edema the number of visible holes is increased (in severe edema all holes are visible). There were significant differences between normals and patients (considering skin mark length, number of visible holes and disappearance times).

CONCLUSIONS

The two testers separated patients with different severity of edema due to chronic venous or lymphatic problems. In severe lymphatic problems all parameters were different (p < 0.02) from those observed in venous disease. A reproducibility study indicated that the ET tests have minimal variations in mark visibility or length or hole numbers (for the ET2).

Angioplasty of lower limb arterial stenoses under ultrasound guidance: single-center experience

PURPOSE

To examine the feasibility and utility of ultrasound-guided angioplasty for treating lower limb stenoses.

METHODS

Duplex ultrasonography was employed to guide 55 balloon dilation procedures (27 iliac, 26 superficial femoral, 1 profunda, and 1 vein graft) with the help of a special ultrasound catheter (EchoMark). Ultrasound was used to determine balloon size, monitor guidewire passage, direct the dilation, and judge procedural success. Angiography was performed prior to the procedure to confirm preprocedural ultrasound findings and afterward to compare with duplex visual and hemodynamic parameters of success (peak systolic velocity ratio < 2.0).

RESULTS

The balloon size determined from duplex measurements correlated in all cases with sizes selected based on the angiographic image. Guidewire visualization was possible in 95% of the cases. Angioplasty using ultrasound alone was feasible in 84%; inability to obtain a satisfactory image owing to vessel tortuosity, calcification, and bowel gas accounted for the failures. Against the duplex success criterion, initial completion angiograms had an accuracy of 76%, sensitivity of 76%, and specificity of 100%. The additional time for ultrasound guidance averaged 42 +/- 12 minutes for all cases.

CONCLUSIONS

Our results show that ultrasound guidance is feasible in routine clinical practice. In this series of well-selected cases of arterial stenoses, angioplasty was performed safely using ultrasound guidance alone in over 80% of the cases. Fluoroscopic monitoring is needed when ultrasound visualization is suboptimal.

Ultrasonic plaque character and outcome after lower limb angioplasty

PURPOSE

The value of ultrasonic plaque characteristics in identifying patients at "high-risk" of restenosis after percutaneous transluminal angioplasty (PTA) was studied.

METHODS

Thirty-one arterial stenoses (6 common iliac, 2 external iliac, 1 profunda femoris, 21 superficial femoral, and 1 popliteal) in 17 patients who underwent angioplasty were studied by means of duplex scanning. With a computer-based program, B-mode images were digitized and normalized using 2 reference points, blood and adventitia. A grey level of 0 to 5 was allocated for the lumen (blood) and 180 to 190 for the adventitia on a linear gray scale of 0 to 255 (0 = absolutely black; 255 = absolutely white), and the overall plaque gray-scale median (GSM) of the pixels of the plaque was used as a measure of plaque echodensity. After PTA, follow-up of stenoses was done on day 1, weekly for 8 weeks, at 3 months, 6 months, and 1 year. The total plaque thickness (sum of anterior and posterior components), minimal luminal diameter (MLD), and peak systolic velocity ratio (PSVR) were measured for all stenoses. An increase of more than 2 in the PSVR was the duplex criterion used to signify restenosis.

RESULTS

The GSM of the stenoses before angioplasty ranged from 6 to 71 (mean, 31.3 +/- 17.9); 17 stenoses had a GSM less than 25 (mean, 18.7 +/- 5.3), and 14 had a GSM more than 25 (mean, 46.4 +/- 15.8). When the GSM was less than 25, the absolute reduction in plaque thickness on day 1 post-PTA was 3.3 +/- 1.8 mm, in contrast to 1.8 +/- 1.6 mm when GSM was more than 25 (P <.03). The restenosis rate (PSVR more than 2) was 41% at 6 months and remained unchanged at 1 year. When the GSM was less than 25, restenosis occurred in 11% of lesions, in comparison with 78% when the GSM was more than 25 (P <.001).

CONCLUSION

Plaque echodensity can be used to evaluate stenoses before PTA, to predict initial success and identify a subgroup that has a high prevalence of restenosis. The identification of a group at "high-risk" of restenosis can improve the selection of patients for the procedure and also be used in prospective studies on the prevention of restenosis.

Treatment of severe intermittent claudication with PGE1--a short-term vs a long-term infusion plan--a 20 week, European randomized trial--analysis of efficacy and costs

The efficacy, safety, and cost of prostaglandin E1 (PGE1) in the treatment of severe intermittent claudication was studied by comparing a long-term treatment protocol (LTP) with a short-term treatment protocol (STP) in a randomized 20-week study. The study included 109 patients (96 completed the study) with an average total walking distance of 65.5 +/- 8 m (range 20-109). Phase 1 was a 2-week run-in phase (no treatment) for both protocols. In LTP, phase 2 was the main treatment phase. In the LTP, treatment was performed with 2-hour infusions (60 microg PGE1, 5 days each week for 4 weeks). In phase 3 (4-week interval period) PGE1 was administered twice a week (same dosage). In phase 4 (monitoring lasting 3 months, from week 9 to 20) no drugs were used. In STP, phase 2 treatment was performed in 2 days by a 2-hour infusion (1st day: morning 20 microg, afternoon 40 microg; 2nd day morning and afternoon 60 microg). The reduced dosage was used only at the first cycle (week 0) to evaluate reduced tolerability or side effects. Full dosage (60 microg b.i.d.) was used for all other cycles. The same cycle was repeated at the beginning of weeks 4, 8, and 12. The observation period was between weeks 12 and 20. A treadmill test was performed at inclusion, at the beginning of each phase, and at the end of the 20th week. A similar progressive physical training plan (based on walking) and a reduction in risk factors levels plan was used in both groups. Intention-to-treat analysis indicated an increase in walking distance, which improved at 4 weeks (101.5% in STP vs 78.3% in LTP), at 8 weeks (260.9% STP vs 107.3% LTP), and at 20 weeks (351% STP vs 242% LTP). Comparable increases in pain-free walking distance were observed in the two groups. No serious drug-related side effects were observed. Local, mild adverse reactions were seen in 7% of the treated subjects in the LTP and 5% in the STP. Average cost of LTP was approximately 6,588 ECU; for STP the average cost was approximately 1,881 ECU. The cost to achieve an improvement in walking distance of 1 m was 35.6 ECU with the LTP and 9.45 ECU with the STP (26% of the LTP cost; p<0.02). For an average 100% increase in walking distance the LTP cost was 1,937 ECU vs 550 ECU with STP (p<0.02). The cost of PGE1 (including infusion and operative costs) was 25% of the total cost for LTP (24.9% for STP). In summary, between-group-analysis favors STP, in terms of walking distance and costs. Results indicate good efficacy and tolerability of PGE1 treatment. With STP less time is spent in infusion and more can be spent in the exercise program. STP reduces costs, speeds up rehabilitation, and may be used in a larger number of nonspecialized units available to follow the protocol.

Prevalence and distribution of incompetent perforating veins in chronic venous insufficiency

PURPOSE

The purpose of this study was the investigation of the prevalence and distribution of incompetent perforating veins (IPVs) in patients with different classes of chronic venous insufficiency (CVI) as defined by the updated clinical, etiologic, anatomic, and pathologic classification (CEAP) in relation to the pattern and the extent of venous reflux.

MATERIAL AND METHODS

The study included 468 limbs of 330 subjects who ranged in age from 18 to 101 years (median, 49 years). The investigation entailed a medical history, a clinical examination, and color flow duplex imaging of the lower limb veins, which were performed by the same vascular surgeon operator. The patients were classified into 7 clinical classes according to CEAP. The superficial and deep venous systems were scanned, with an emphasis on the detection of IPVs. Venous reflux was considered abnormal when its duration exceeded 0.5 seconds. IPVs were classified as medial, posterior, and anterolateral in the upper, middle, or lower third of the thigh or calf (9 thigh and 9 calf fields).

RESULTS

The IPVs were found mainly in the medial aspect, more frequently in the middle third of calf, followed by the lower calf and the middle thigh. IPVs were rare in the lateral aspect of the thigh, the medial upper and posterior lower thigh and the posterior upper and lower calf. The prevalence of the IPVs and of deep vein incompetence increased significantly with the clinical severity of CVI (r =.95, P <.01, and r =.9, P <.01, respectively). In the limbs with a documented perforating vein (PV) incompetence, the ratios of calf-to-thigh IPVs and of superficial-and-deep (S + D) over superficial-alone (S; [S + D]/S] venous incompetence increase significantly (r =.87, P <.01 and r =.9, P <.01, respectively) with CEAP grade. The prevalence of reflux involving all systems (S + D + PV) increases significantly (r =.9, P <.01) with clinical severity. In legs with CVI of CEAP 2 to 6, reflux was invariably proximal (thigh) and distal (below knee).

CONCLUSION

In CVI, IPVs are located predominately in the medial aspect of the lower extremity, more often in the middle third of the calf, followed by the lower calf and middle thigh. The prevalence of IPVs and their calf-to-thigh ratio increase linearly with the clinical severity of CVI. Both the prevalence of deep vein incompetence and the ratio of superficial and deep to superficial ([S + D]/S) increase linearly with CEAP classification. These findings support the significant relationship between deep venous reflux and PV incompetence, although the latter may exist in the absence of the former. In CEAP classes 2 to 6, reflux is invariably proximal and distal. Incompetence involving all systems (S + D + PV) increases in prevalence with the severity of CVI.

Shock waves in vascular diseases: an in-vitro study

Three human aortic specimens were used for this in-vitro study on the effects of shock waves on the arterial wall. Specimen one was from a normal (for age) healthy aorta. The full abdominal length was used (including mesenteric and renal arteries and the aortoiliac bifurcation), divided into six pieces (3 cm). The pieces were placed and fixed into degassed water. Shock waves (SW) were focused onto the aortic wall by means of a B-mode ultrasound imager. An SW generator (Minilith SL1, Storz Medical AG, Kreuzlingen, Switzerland) was used for setting of energy flux density between 0.03 and 0.5 mJ/mm2. The six aortic pieces (excluding piece 1, placed in water and left untreated as control) were treated with SW at increasing energy levels. A second aortic specimen of a man with arteriosclerotic plaques was also used and the experiment repeated at energy levels 1, 5, and 8. Another specimen of normal thoracic aorta was exposed at energy levels 1 and 8 only. Energy levels delivered onto the aortic walls were selected from theoretically destructive levels to minimal levels known not to alter vascular tissues. High-resolution ultrasounds of the aortic segments were performed with a 10 MHz high-resolution, broad-band (ATL 3000, USA) probe in water before and after SW application to detect structural changes in the wall after SW. Histology was performed with a standard hematoxylin-eosin staining.

RESULTS

The aortic pieces did not show macroscopic damages at visual examination, and at the ultrasound examination no visible changes were observed even at higher levels of SW energy. Also no effects were seen by histology. In conclusion, no damaging effects were observed, visually, by ultrasound, or by histology. At these energy levels SW appear to be safe and do not produce any damage to the aortic wall. Therefore, SW could be considered a safe, nondamaging procedure for potential treatment (ie, thrombolysis) in which vessel walls could be involved. Theoretically it is possible that functional changes could be observed in vivo including cell permeability modifications and other alterations (including changes in the potential of the cells in SW fields to modify themselves and to divide). At the energy levels described in this study SW could, theoretically be, safely used for vascular applications (ie, treating venous and arterial thrombi or in arterial plaques modification) without altering major, structural, arterial wall characteristics. Lesions or alterations that have a different density from the normal wall (thrombi or plaques) could be differently sensitive to the same dosage of SW. These differences in acoustic impedance characteristics could be used for potential treatments with SW without damaging the arterial wall.

Peter B. Samuels Award. Restenosis after percutaneous transluminal angioplasty

BACKGROUND

Determine the feasibility of studying the natural history of the atherosclerotic plaque following percutaneous transluminal angioplasty (PTA), using duplex scanning.

METHODS

Twenty-three patients with 40 stenoses (>70% and <5 cm in length) in the iliac and femoro-popliteal segments were studied by duplex scanning before PTA, on day 1, weekly for 8 weeks, and at 3 months, 6 months, and 1 year. The following measurements were made: thickness of the plaque, minimal lumen diameter (MLD), and peak systolic velocity ratio (PSVR). A PSVR >2.0 was used to indicate >50% lumen diameter reduction.

RESULTS

Thirty stenoses were available for measurement and analysis. Mean reduction in plaque thickness after angioplasty was greater in echolucent plaques (2.33 +/- 0.9 mm) than echogenic plaques (0.83 +/- 0.6 mm; P < 0.0001). Successful angioplasty (PSVR <2.0) and increase in MLD in echolucent plaques was the result of plaque compression; in echogenic plaques, of wall dilatation. The incidence of restenosis (PSVR >2.0) at 6 months was 12 of 30 (40%) remaining unchanged at 1 year; of the lesions that restenosed, 33% recurred before week 8 and the remainder between weeks 8 and 24, suggesting different mechanisms. During follow-up, all plaques showed "growth"; <2 mm in 17 (57%; group A) and >2 mm in the remaining 13 (43%; group B). The incidence of restenosis (PSVR >2.0) was 4 of 17 (23%) in group A and 8 of 13 (61%) in group B (P <0.05).

CONCLUSION

Duplex scanning provides valuable information on both luminal diameter and plaque thickness; it may be used to study the natural history of plaques following angioplasty and also the effects of therapeutic agents aimed at reducing restenosis.

Carotid plaque characterization using digital image processing and its potential in future studies of carotid endarterectomy and angioplasty

PURPOSE

To corroborate the validity of a computerized methodology for evaluating carotid lesions at risk for stroke based on plaque echogenicity.

METHODS

The records of 96 carotid endarterectomy patients (59 men; median age 69.5 years, range 52 to 83) with stenoses > 50% were studied retrospectively. Forty-one patients (43%) had been symptomatic preoperatively. All patients had undergone computed tomography (CT) to detect infarction in the carotid territory and a duplex scan to measure carotid stenosis. Plaque echogenicity was analyzed by computer, expressing the echodensity in terms of the gray scale median (GSM). The incidence of CT-documented cerebral infarction was analyzed in relation to symptomatology, percent stenosis, and echodensity.

RESULTS

Symptoms correlated well with CT evidence of brain infarction: 32% of symptomatic patients had a positive CT scan versus 16% for asymptomatic plaques (p = 0.076). The mean GSM value was 56 +/- 14 for plaques associated with negative CT scans and 38 +/- 13 for plaques from patients with positive scans (p < 0.0001). However, there was no difference in the GSM value between plaques with > or < 70% stenosis. Furthermore, the incidence of CT infarction was 40% in the cerebral territory of carotid plaques with a GSM value < 50 and only 9% in those with a GSM > 50 (p < 0.001).

CONCLUSIONS

Computerized analysis of plaque echogenicity appears to provide clinically useful data that correlates with the incidence of cerebral infarction and symptoms. This method of analyzing plaque echolucency could be used as a screening tool for carotid stent studies to identify high-risk lesions better suited to conventional surgical treatment.

The management of venous aneurysms of the lower extremities

Vein aneurysms have been reported in both the deep and superficial vein system of the lower extremities. In the iliofemoral area of the deep system the most common presentation is of an abdominal or iliac fossa mass while thromboembolism is not uncommon. The aneurysms are thought to result mainly from a congenital weakness of the vein wall, with an AV fistula present in over 50% of cases. Existing AV fistulae must be ligated; however, as the results of simple AV fistula or vein ligation are poor, reconstruction should always be attempted. Aneurysm excision with an end-to-end anastomosis might be feasible in the proximal iliac segment while the use of PTFE grafts or the LSV seems appropriate in cases of attempted reconstruction. In the popliteal area there is agreement on the aetiology (congenital, traumatic, post operative and after an AV fistula formation), the symptomatology (mainly thromboembolism) and the diagnosis (duplex scanning). Symptomatic cases should be treated surgically since the reported surgical results are excellent while the incidence of recurrent pulmonary embolism in patients treated conservatively exceeds 80%. Asymptomatic popliteal vein aneurysms could remain under close observation only but, if complicated with thromboembolism during the follow-up period, surgery should be performed immediately. The crural and superficial veins represent a minor danger and can be easily treated with ligation and/or excision with excellent results.

How "gold" is the standard? Interobservers' variation on venograms

BACKGROUND

The aim of this study was to determine the degree of agreement between radiologists having different levels of experience, in reporting 151 venograms independently. It was also aimed to assess whether the degree of disagreement would have influenced the final outcome of a thromboprophylactic study and the decision to anticoagulate the patients.

METHODS

Seventy-eight patients undergoing total hip replacement had bilateral venography on postoperative days 8-12. Patients were allocated to receive either a low molecular weight heparin (enoxaparin) with or without TED stockings or a placebo Each of the 151 venograms obtained has been reported on four times.

RESULTS

The overall incidence of deep venous thrombosis was 42% (33 of 78 patients). The range of the Kappa value of each radiologist versus the others was 0.568 to 0.669. There was a significant decrease in the incidence of deep venous thrombosis in the treatment versus the placebo groups. On an intention to treat all diagnosed thrombi, a difference of up to 16% was demonstrated between the report of individual radiologists and the panel. This difference was reduced to 8% when only thrombi proximal to the calf were considered clinically significant.

CONCLUSIONS

These differences reflect the radiologist's experience and frequency of reporting on venograms and should be taken into account when studies for thromboprophylaxis are planned.

Cardiovascular outcomes in type 2 diabetes. A double-blind placebo-controlled study of bezafibrate: the St. Mary's, Ealing, Northwick Park Diabetes Cardiovascular Disease Prevention (SENDCAP) Study

OBJECTIVE

To determine whether serum lipid intervention, in addition to conventional diabetes treatment, could alter cardiovascular outcomes in type 2 diabetes.

RESEARCH DESIGN AND METHODS

There were 164 type 2 diabetic subjects (117 men, 47 women) without a history of clinical cardiovascular disease randomized to receive either bezafibrate or placebo daily on a double-blind basis in addition to routine diabetes treatment and followed prospectively for a minimum of 3 years. Serial biochemical and noninvasive vascular assessments, carotid and femoral artery B-mode ultrasound measurements, and those pertaining to coronary heart disease (CHD)--clinical history, the World Health Organization (WHO) cardiovascular questionnaire, and resting and exercise electrocardiogram (ECG)--were recorded.

RESULTS

Bezafibrate treatment was associated with significantly greater reductions over 3 years in median serum triglyceride (-32 vs. 4%, P = 0.001), total cholesterol (-7 vs. -0.3%, P = 0.004), and total-to-HDL cholesterol ratio (-12 vs. -0.0%, P = 0.001), and an increase in HDL cholesterol (6 vs. -2%, P = 0.02) as compared with placebo. There was a trend toward a greater reduction of fibrinogen (-18 vs. -6%, P = 0.08) at 3 years. No significant differences between the two groups were found in the progress of ultrasonically measured arterial disease. In those treated with bezafibrate, there was a significant reduction (P = 0.01, log-rank test) in the combined incidence of Minnesota-coded probable ischemic change on the resting ECG and of documented myocardial infarction.

CONCLUSIONS

Improving dyslipidemia in type 2 diabetic subjects had no effect on the progress of ultrasonically measured arterial disease, although the lower rate of "definite CHD events" in the treated group suggests that this might result in a reduction in the incidence of coronary heart disease.

Circadian pattern of post-surgical fatal pulmonary embolism

BACKGROUND

The circadian distribution of fatal pulmonary thromboembolism in general surgical patients is unknown.

PATIENTS AND METHODS

One hundred consecutive cases of pulmonary embolism, with reliable clinical notes and data, were studied (67 men and 33 women; mean age 71 years). Only post-surgical cases were considered in this analysis. Patients had undergone elective (78%) or emergency abdominal surgery (22%). Correct prophylaxis (according to the Windsor Consensus Statement) had been used in 12%. Cases were grouped according to the time of onset of signs and symptoms related to pulmonary embolism at one hour intervals.

RESULTS

The maximum incidence of fatal pulmonary embolism was between 7.00 a. m. and 1.00 p. m. with the highest peaks at 9.00 and 11.00 a. m. 9% of deaths) (P < 0.02). When results from this study were compared to a previous study no significant difference was observed between the distribution profile of cases from general medical wards and surgical wards.

CONCLUSION

It appears that in surgical patients there is a circadian pattern in pulmonary embolism as already documented in medical patients.

Prevalence and clinical significance of posterolateral thigh perforator vein incompetence

PURPOSE

Posterolateral thigh perforator (PLTP) veins are part of the lateral thigh venous system, which in most people remains undeveloped. This study was designed to determine the prevalence and clinical significance of these veins.

METHODS

Over the past 6 years, 2820 lower limbs with signs and symptoms of chronic venous disease (CVD) were evaluated for venous reflux using color flow duplex imaging. Superficial, perforating, and deep veins were examined in the standing, sitting, and reversed Trendelenburg positions. PLTP veins were best identified in the standing position with the patient facing away from the examiner.

RESULTS

Twenty-six incompetent PLTP veins were found in 24 limbs (0.85%) of 21 patients (mean age, 43 +/- 16 years; range, 22 to 77 years). All PLTP veins pierced the fascia lata 12 to 25 cm (mean, 16 +/- 3 cm) above the popliteal skin crease in the lateral aspect of the thigh. At this level, the PLTP veins dove posteriorly 3 to 8 cm to join primarily tributaries of the deep femoral vein, superficial femoral vein, or both. Eight PLTP veins were duplicated at 1 to 2 cm below the fascia. Seven PLTP veins gave rise to superficial tributaries that were extended to the lower lateral and posterior thigh, whereas the remaining 19 PLTP veins gave rise to tributaries alongside the lesser saphenous vein and the anterior arch of the greater saphenous vein. On nine occasions, reflux was found in the PLTP veins and their associated tributaries alone. In all of these cases, reflux was adequately controlled with a tourniquet placed distal to the fascial defect. In the remaining 17 PLTP veins, reflux was also seen in the greater saphenous vein, the lesser saphenous vein, or both. None of the limbs that had PLTP vein reflux alone exceeded CVD class 3. When PLTP vein reflux was combined with saphenous reflux, there were five limbs classified as CVD class 4 and one limb each as CVD classes 5 and 6. Twenty limbs underwent ligation and stripping of the varicosities. Three of the earlier patients in the series underwent incomplete operations, which resulted in immediate residual varicosities from the PLTP tributaries. All three patients underwent reoperation successfully within a year.

CONCLUSIONS

The prevalence of PLTP vein reflux is quite low. Reflux in the PLTP veins alone is associated with mild to moderate clinical presentation. However, when it is combined with saphenous reflux skin damage can be present. Failure to recognize PLTP veins may result in an incomplete or unnecessary operation, leaving the patients with residual varicose veins.

Where does venous reflux start?

PURPOSE

This study was designed to identify the origin of lower limb primary venous reflux in asymptomatic young individuals and to compare patterns of reflux with age-matched subjects with prominent or clinically apparent varicose veins.

METHODS

Forty age- and sex-matched subjects with no symptoms (age, 15 to 35 years; 80 limbs; group A), 20 subjects (age, 19 to 32 years; 40 limbs) with prominent but nonvaricose veins (n = 26 limbs; group B), and 50 patients (age, 17 to 34 years; 100 limbs) with varicose veins (n = 64; group C) were examined with color flow duplex imaging. All proximal veins (above popliteal skin crease), superficial, perforator, and deep, in the lower limb were examined in the standing position, and all the distal veins in the sitting position. Patients who had a documented episode of superficial or deep vein thrombosis, previous venous surgery, or injection sclerotherapy were excluded from the study.

RESULTS

The prevalence of reflux in group A was 14% (11 of 80), in group B 77% (31 of 40), and in group C 87% (87 of 100). In more than 80% of limbs in the three groups, reflux was confined to the superficial veins alone. Deep venous reflux or combined patterns of reflux were uncommon even in group C. Reflux was detected in all segments of the saphenous veins and their tributaries. In the 125 limbs that had superficial venous incompetence, the below-knee segment of the greater saphenous vein was the most common site of reflux (85, 68%), followed by the above-knee segment of greater saphenous vein (69, 55%) and the saphenofemoral junction (41, 32%). Nonsaphenous reflux was rare (3, 2.4%). Reflux in the lesser saphenous vein (21, 17%) was seen in all groups, whereas involvement of both greater and lesser saphenous veins (8, 6.4%) was seen in group C alone. The incidence of multisegmental reflux was significantly higher in group C (61 of 64, 95%) than in group A (two of 11, 18%) or group B (14 of 26, 54%). The prevalence of distal reflux was comparable in all groups.

CONCLUSIONS

Primary venous reflux can occur in any superficial or deep vein of the lower limbs. The below-knee veins are often involved in asymptomatic individuals and in those who have prominent or varicose veins. These data suggest that reflux appears to be a local or multifocal process in addition to or separate from a retrograde process.

Clostridium difficile colitis after aortic surgery

OBJECTIVE

To determine the incidence and outcome of Clostridium difficile colitis (CDC) following aortic surgery.

DESIGN

Retrospective clinical study, and case-note review.

PATIENTS

Of 180 patients undergoing aortic surgery for either aneurysmal or occlusive disease between 1 September 1994 and 31 August 1996 (24 months), 15 (8.4%) developed CDC. There were 12 male and three female patients of median age 65 (range 46-84).

RESULTS

Two patients died from multiple organ failure in association with CDC, one of whom underwent negative relaparotomy for suspected ischaemic bowel because the diagnosis of CDC had not been entertained. Previously identified risk factors for CDC comprised: age > 65 (eight); renal impairment (four); chronic obstructive airways disease (seven); coexistent malignancy (three); admission from another hospital (four); H2 antagonist therapy (13); ITU (nine); and/or HDU care (14). Diarrhoea commenced a median of 9 (range 5-26) days, and CDC, was diagnosed a median of 14 (range 10-26) days after operation. All patients received intravenous Cefuroxime, originally prescribed as prophylaxis, for a median of 6 (range 3-16) days prior to onset of CDC. Two patients received 1 additional antibiotic; one received 2; two received 3; and one received 4 prior to onset of CDC.

CONCLUSIONS

CDC is a common and potentially serious complication of vascular, and in particular, aortic surgery. Although such patients often possess several risk factors for CDC, colitis frequently follows prolonged 'prophylactic' cephalosporin administration, which should therefore be avoided.

Effect of lightweight compression stockings on venous haemodynamics

OBJECTIVE

To investigate the effect of lightweight graduated elastic stockings on venous haemodynamics.

DESIGN

The amount of reflux and function of the calf muscle pump were evaluated before and after the application of lightweight graduated compression stockings using air-plethysmography. Each patient acted as his own control and the Wilcoxon rank sum test was used.

SETTING

Vascular laboratory of a teaching hospital.

SUBJECTS

19 female patients (20 limbs) with moderate varicose veins.

MAIN OUTCOME MEASURES

The haemodynamic parameters: amount of reflux (VFI), ejection fraction (EF) of the calf muscle pump after one tiptoe exercise, residual volume fraction (RVF) after 10 tiptoes and venous volume (VV) were determined for each patient with and without the three strengths of stocking (7, 10, 14 mmHg at the ankle) using air-plethysmography.

RESULTS

The mean VFI decreased from 5.7 ml/sec without stockings to 4.6+/-2.2, 3.9+/-2.3, and 3.4+/-1.8 with stockings of 7, 10 and 14 mmHg respectively (p<0.0002). Similarly the RVF showed a significant decrease with all three stockings from the initial value 42.3% to 36.3, 34.4 and 31.5 respectively (p<0.03). EF showed an increase from 49.2% to 51.4, 50.9 and 56, but only with the latter was the increase significant (p<0.02). VV decreased from 118.8 ml to 113.6+/-24.4 (p>0.05), 104.2+/-22.8 and 109.1+/-27.4 (p<0.008) with 10 and 14 mmHg.

CONCLUSIONS

The results indicate that lightweight compression stockings can have a significant effect on venous haemodynamics. They decrease the residual volume fraction and by inference ambulatory venous pressure. This is the result of an increase in the ejection fraction with a decrease of reflux. The results offer a possible physiological explanation on the relief of symptoms experienced when patients with varicose veins wear lightweight stockings.

Pre-bypass quality assessment of the long saphenous vein wall with ultrasound and histology

OBJECTIVES

Pre-existing unsuspected wall changes in saphenous vein grafts have been implicated in the graft outcome. Pre-bypass assessment of the vein may identify grafts at high risk for failure. This study was conducted to evaluate preoperatively the quality of the long saphenous vein (LSV) wall with ultrasound and histology.

DESIGN

Prospective clinical study.

MATERIAL AND METHODS

Three particular LSV segments, ankle, knee and mid-thigh, were evaluated preoperatively by ultrasound in 40 limbs of 38 patients, candidates for coronary artery bypass grafting. The venous wall was characterised based on its thickness and echogenicity in three categories: normal, moderately and severely fibrotic. LSV specimens taken from the above sites were also grouped into the same three categories based on their fibrotic content found on histology.

RESULTS

In total, 89 vein specimens were evaluated. On ultrasound, 81 specimens were detected as normal (91%), seven as moderately (8%) and one as severely fibrotic (1%). On histology, only eight specimens were found normal (9%), 75 with moderate (84%) and six with severe fibrosis (7%). Similar wall characterisation with both examinations was found in only 19% (17/89) of the specimens. Eighty-one specimens (91%) had some degree of fibrosis on histology. Different grades of fibrosis were found on histology in different sites of the same vein.

CONCLUSIONS

Pre-existing wall changes are very common in vein grafts used for bypass surgery. However, the ultrasonic characterisation of the venous wall preoperatively cannot reliably identify these changes.

Epidemiology and costs of venous diseases in central Italy. The San Valentino Venous Disease Project

The Prevalence of Early Atherosclerosis study aims to define the prevalence of subclinical atherosclerosis in a typical population of central Italy. A concomitant study evaluates the prevalence of venous diseases. The prevalence of superficial and deep venous disease, the prevalence of venous thrombosis and pulmonary embolism, and the prevalence of the most common venous malformations were studied through use of medical history, a questionnaire, and noninvasive investigations. The costs of venous problems were also considered. Of some 2000 inhabitants, 746 (379 women; mean age 46.3 +/- 7 years; range eight to ninety-four) have been screened. No significant difference in trend increase of the relationship age/percent of subjects with venous problems was observed for superficial venous disease. The increase in the proportion of subjects with lipodermatosclerosis and venous ulcerations appeared to be correlated with age (r = 0.543). Evidence accepted for pulmonary embolisms was pulmonary angiogram or evidence on ventilation+perfusion lung scans. According to these criteria the number of documented deep vein thromboses and pulmonary embolisms was very limited with a larger number of suspected disease entities. There was no significant correlation between age and pulmonary embolism or deep venous thrombosis distribution. The number of venous and/or arteriovenous malformations was comparable along the age axis in the different age groups. Only a limited number of these malformations (in less that 1% of subjects) had caused a clinical problem. The treatments used for venous problems have been reported in a questionnaire and subdivided into occasional treatments and chronic treatments (when used for periods longer than twelve months). The percent of subjects using different treatment was also studied. Treatments were divided in: (1) over-the-counter products (or any treatment not requiring prescription); (2) specialized drug (for venous diseases); (3) compression; (4) surgery (any type of surgical treatment); (5) sclerotherapy; (6) combined treatments (ie, sclerotherapy and surgery); (7) alternative treatments (herbal products etc). Finally, the average costs per year for treatment, for investigations, and the costs due to lost working days were recorded. In conclusion some 12% of the evaluated population sample (male population 46%) had or had been affected in the past by a venous problem and 50% of them had received some type of treatment.

Duplex scanning in the postoperative surveillance of patients undergoing total hip arthroplasty

Color flow duplex imaging is a well-established method for the diagnosis of deep vein thrombosis in symptomatic patients; however, the sensitivity and specificity of duplex scanning compared with venography in high-risk asymptomatic patients are not known. Consecutive patients undergoing total hip arthroplasty who consented to have bilateral venography on days 8 to 12 were included in this prospective study. One hundred and fifty-one venograms were finally obtained in 78 patients. All duplex scanning was performed with the Ultramark 9 ATL (Advanced Technology Laboratories) by one investigator. In the beginning of the study, the first 44 legs, only the femoropopliteal segment was tested and the result was based on B-mode compression; the sensitivity for the duplex was 56% (5/9), and the specificity, 94% (33/35). In the next 107 legs, the addition of color to our criteria improved the sensitivity of the duplex scan from 55% to 93% (13/14) for the femoropopliteal segment and the specificity from 94% to 99% (92/93). For the calf segment, in the same 107 legs, using the color facility of the duplex, the sensitivity and specificity were 79% (15/19) and 97% (85/88), respectively. The color facility of new-generation machines makes duplex scanning reliable for the detection of proximal deep vein thrombosis, even in asymptomatic high-risk patients. For the detection of calf deep vein thrombosis, however, more experience is needed. A larger study is necessary to confirm these preliminary data.