Biomedical subjects

H Sillesen

Publications and source records attributed to H Sillesen.

At least 19 recordsLinked to original sources

PubMed1998

The use of intravascular ultrasound for intraoperative assessment during semiclosed thromboendarterectomy.

To evaluate the application of intravascular ultrasound (IVUS) for intraoperative assessment of semiclosed thromboendarterectomy (TEA), IVUS images of the iliofemoral segment in 20 patients were obtained. The configuration and size of residual atherosclerotic material were evaluated. Stenoses in the artery proximal to the endarterectomized area were measured and, along with any remaining material, related to patency. Patency was evaluated at clinical controls after 3, 6, 12 and 24 months with duplex scanning and ankle-brachial index. In 10 cases (50%), material left behind from the endarterectomy was detected in the artery by IVUS. The material was removed in five cases. The part of the iliac artery proximal to the endarterectomized segment was visualized in 14 cases and showed minor stenoses in 10 cases. After follow-up at a median of 8 months (range 1-24), occlusion had occurred in one of 20 patients and restenosis (> 50%) had developed in two (10%). At this point, patency cannot be related to IVUS findings. We conclude that IVUS is a feasible method for intraoperative assessment of semiclosed TEA. The rate of early failures due to residual material might be reduced by this new application of IVUS.

Adult↗

PubMed1998

Quantitative analysis of ultrasound B-mode images of carotid atherosclerotic plaque: correlation with visual classification and histological examination.

This paper presents a quantitative comparison of three types of information available for 52 patients scheduled for carotid endarterectomy: subjective classification of the ultrasound images obtained during scanning before operation, first-and second-order statistical features extracted from regions of the plaque in still ultrasound images from three orthogonal scan planes and finally a histological analysis of the surgically removed plaque. The quantitative comparison was made with the linear model and with separation of the available data into training and test sets. The comparison of subjective classification with features from still ultrasound images revealed an overall agreement of 60% for classification of echogenicity and 70% for classification of structure. Comparison of the histologically determined relative volume of soft materials with features from the still images revealed a correlation coefficient of r = -0.42(p = 0.002). for mean echogenicity of the plaque region. The best performing feature was of second order and denoted Contrast (r = -0.5). Though significant, the latter correlation is probably not strong enough to be useful for clinical prediction of relative volume of soft materials for individual patients. Reasons for this is discussed in the paper, together with suggestions for improvements.

Arteriosclerosis↗

PubMed1998

Clinical significance of intraplaque hemorrhage in carotid artery disease.

Previous research has indicated that intraplaque hemorrhage is a significant pathogenetic factor in carotid artery disease. The present study was undertaken to evaluate whether the clinical presentation of patients with carotid artery disease could be correlated to quantitative histologic analysis of surgically removed carotid specimens. Two-hundred-seventy patients undergoing carotid endarterectomy comprised the material. Symptomatology was assessed preoperatively. After removal, the carotid plaques were analyzed histologically for relative volume content of hemorrhage, fatty tissue, fibrous tissue, and calcification. There was no difference between asymptomatic and symptomatic patients. However, when the time interval between onset of symptoms and surgery was considered, plaques from patients with recent symptoms contained more hemorrhage compared with plaques from asymptomatic patients (p = 0.0045). The paper supports the theory of intraplaque hemorrhage being related to clinical events in carotid artery disease.

Adult↗

PubMed1998

Multi-angle compound imaging.

This paper reports on a scanning technique, denoted multi-angle compound imaging (MACI), using spatial compounding. The MACI method also contains elements of frequency compounding, as the transit frequency is lowered for the highest beam angles in order to reduce grating lobes. Compared to conventional B-mode imaging MACI offers better defined tissue boundaries and lower variance of the speckle pattern, resulting in an image with reduced random variations. Design and implementation of a compound imaging system is described, images of rubber tubes and porcine aorta are shown and effects on visualization are discussed. The speckle reduction is analyzed numerically and the results are found to be in excellent agreement with existing theory. An investigation of detectability of low-contrast lesions shows significant improvements compared to conventional imaging. Finally, possibilities for improving diagnosis of atherosclerotic diseases using MACI are discussed.

Animals↗

PubMed1998

Conservative treatment, amputation or revascularisation for critical limb ischaemia.

Patients with critical chronic limb ischaemia may be addressed by different approaches: conservatively with control of risk factors and in some cases also medical treatment, or by amputation, primarily or secondarily, following attempt to revascularise, or treatment may be surgical, either with endovascular or open vascular surgery. The different options are shortly described, with indications and likely results which may be obtained in each case. The paper concludes that no matter what treatment is considered, control of risk factors is of benefit. Patients who, judged by the vascular surgeon, are operable, and who are physically active and without serious medical risk factors, are best treated with open surgical revascularisation. In high risk cases or when inoperable, medical therapy may be an option. Endovascular treatment may be considered in patients with high surgical risk. Primary amputation should be considered in cases where outcome of surgical treatment may be seriously affected by medical risk factors, in cases with progressive ischaemia, in cases where the chances of successful surgery are small or when the patient is in a situation where the benefit of surgery is negligible.

Amputation, Surgical↗

PubMed1997

Influence of tissue preservation methods on arterial geometry and echogenicity.

Thoracic porcine aortas from 5 pigs were investigated with 7.5-MHz ultrasound in vitro at low and high transmural pressure before and after the following tissue preservation methods were applied: 1. Storage in frozen condition (-12 degrees C) for 24 h followed by thawing; 2. fixation in formalin at zero transmural pressure for 24 h; and 3. fixation with formalin for 24 h while applying 74 mmHg of transmural pressure from within the lumen and a tensile force to longitudinally stretch the artery. Fixation in formalin at zero transmural pressure resulted in swelling of the arterial wall (25 +/- 40%, p < 0.02, at low transmural measurement pressure) and in decreased echogenicity (-23 +/- 38%, p < 0.01) of the arterial vessel wall. No changes in this respect were found after storage in a frozen condition nor after fixation in formalin at high transmural pressure which, therefore, are more appropriate procedures for fixation of arteries prior to in vitro ultrasound examination if geometry is important.

Animals↗

PubMed1997

Lipid-rich carotid artery plaques appear echolucent on ultrasound B-mode images and may be associated with intraplaque haemorrhage.

OBJECTIVE: To relate the histological composition of carotid artery plaques with morphology as evaluated by B-mode ultrasound. DESIGN: Prospective study. MATERIAL AND METHODS: Seventy-eight symptomatic patients underwent carotid endarterectomy after preoperative ultrasound Duplex scanning evaluating plaque morphology. Morphometric analysis of the removed specimen was performed in order to quantify content of lipid, haemorrhage, calcification and fibrous tissue. RESULTS: Echolucent plaques contained more lipid (p = 0.01) and less calcification (p = 0.01) and fibrous tissue (p = 0.03) than echo-rich plaques. Intraplaque haemorrhage was directly related to lipid content (p = 0.004) and inversely related to amount of fibrous tissue in the plaque (p = 0.02). CONCLUSION: The intensity of the reflected B-mode ultrasound signal appears related to the histological composition of the plaque. The association between intraplaque haemorrhage and a high lipid content may support the theory of the lipid-rich plaque being more prone to rupture.

Arteriosclerosis↗

PubMed1996

Echolucent carotid artery plaques are associated with elevated levels of fasting and postprandial triglyceride-rich lipoproteins.

BACKGROUND AND PURPOSE: Echolucent carotid atherosclerotic plaques are associated with an increased risk of neurological symptoms. Elevated plasma triglycerides is a risk factor for cerebral and coronary infarction. This study examined these individual pathogenetic risk factors to determine whether they were related. METHODS: We included 85 symptomatic patients with at least 40% carotid artery stenosis. Plaque morphology of the relevant artery was evaluated by high-resolution B-mode ultrasonography as echolucent, echo-rich, or intermediate. Fasting and postprandial lipids and lipoproteins were measured before and at hourly intervals for 4 hours after a fatty meal (1 g cream fat per kilogram body weight). RESULTS: When we compared patients with echolucent plaques to patients with echo-rich or intermediate plaques, the former had higher fasting and postprandial plasma triglycerides (P < or = .006), higher chylomicron remnants/VLDL cholesterol (P = .02) and triglycerides (P < or = .004), a larger area under the plasma triglyceride curve 0 to 4 hours after a fatty meal, with (AUCTG-TG oh) or without (AUCTG) subtraction of fasting levels (P = .007 and P = .003), a larger body mass index (P = .03), and were younger (P = .01). Multiple logistic regression analysis found that when age and body mass index were taken into account, fasting plasma and VLDL triglycerides, postprandial chylomicron remnants/VLDL triglycerides, AUCTG-TG oh and AUCTG with odds ratios of 4.1, 3.8, 3.0, 2.7, and 4.3, respectively, were independent predictors of an echolucent plaque. CONCLUSIONS: Echolucent carotid artery plaques are associated with elevated levels of triglyceride-rich lipoproteins in the fasting or postprandial state.

Adult↗

PubMed1995

Simple hyperaemia test as a screening method in the postoperative surveillance of infrainguinal in situ vein bypasses.

OBJECTIVES: To develop a simple protocol for ultrasound Duplex surveillance of infrainguinal vein bypasses. DESIGN: The value of three Doppler waveform parameters, obtained from a single point of the bypass, for identification of stenoses was studied in 91 in situ vein bypasses. Midgraft peak systolic velocity (PSV), pulsatility index (PI) and ratio of hyperaemic and resting time-average mean velocities (TAMV), (TAMV ratio = TAMVhyperaemia/TAMVrest) were correlated with the presence and severity of stenoses as assessed by conventional Duplex scanning and ankle-brachial index (ABI) measurements. The optimal value of the waveform parameters for discrimination between bypasses with and without evidence of stenoses was determined by receiver operating characteristics (ROC) analysis. MAIN RESULTS: Complete Duplex scanning of the entire graft revealed an increase in the peak systolic velocity by a factor 2.5 indicative of significant stenoses in 24 (26%) patients. A PSV below 55 cm/s was a poor indicator of stenoses (sensitivity 46%, specificity 76%) and PI < or = 3.8 only allowed suboptimal discrimination between normal and stenotic bypasses (sensitivity 63%, specificity 75%). The hyperaemic response assessed by TAMV ratio proved the best parameter for identification of graft stenoses. A TAMV ratio of 2.0 or less correctly identified 21 of the 24 lesions (sensitivity 88%, specificity 75%) and none of the three bypasses with evidence of stenoses and TAMV ratios exceeding 2.0 failed during follow-up. CONCLUSIONS: Single point waveform analysis of vein bypass velocity profile at rest and during reactive hyperaemia is a simple screening method providing diagnostic and prognostic information which may be of value in the postoperative surveillance of infrainguinal vein bypasses.

Aged↗

PubMed1995

Seizures following carotid endarterectomy in patients with severely compromised cerebral circulation.

OBJECTIVES: To determine the incidence of postoperative neurological complications following carotid endarterectomy in patients with severely compromised cerebral circulation. DESIGN: Prospective open clinical study. SETTING: Department of Vascular Surgery, University Hospital. MATERIALS AND METHODS: We determined the incidence of postendarterectomy seizures related to haemodynamic impairment in terms of intraoperatively measured perfusion pressure in 151 patients undergoing 153 carotid endarterectomies. MAIN RESULTS: Cerebral perfusion pressure index (ICA/CCA pressure ratio) was significantly reduced (25% or more) in 47% (55/118) of patients with 70-99% stenosis compared to 6% (2/35) of patients with 30-69% stenosis (p < 0.00005). Among the 57 haemodynamically compromised patients five developed seizures considered due to cerebral hyperperfusion five to seven days after surgery. The seizures were associated with headache in two, focal neurological deficits in four and hypertensive episodes in all cases. The symptoms remitted within 2 weeks and no patients suffered cerebral haemorrhage. CONCLUSIONS: Seizures following correction of high grade stenoses causing severe pressure reduction may be more common than previously assumed. Patients at risk should be identified and postoperative blood pressure controlled meticulously.

Carotid Artery, Internal↗

PubMed1995

Preoperative mapping of the saphenous vein: prognostic value on early postoperative results.

A consecutive series of 92 patients had their greater saphenous vein assessed with duplex ultrasound scanning prior to planned infrainguinal bypass procedures. A naturally occurring optimal vein diameter was discovered. It was significantly correlated with higher postoperative ankle-brachial pressure index (ABI) and lesser early postoperative thrombosis. A significant linear regression was found between the pre and postoperative vein diameter.

Aged↗

PubMed1993

Doppler spectral characteristics of infrainguinal vein bypasses.

With the aim of assessing the velocity profile of femoropopliteal and femorocrural vein bypasses, 128 patients undergoing infrainguinal vein bypass surgery entered a postoperative Duplex surveillance protocol, which included clinical assessment and Duplex scanning, using Doppler spectral analysis. Doppler spectra were obtained at three sites in each graft and the following waveform parameters recorded: maximum systolic velocity, minimum diastolic velocity and resistance index. In patent reconstructions systolic velocity decreased by 30% during the first 6 months after surgery. In the absence of arteriovenous fistulas the initially antegrade diastolic velocity was replaced by a retrograde flow within 3 months, whereas a forward flow in diastole was sustained in grafts with patent fistulas. Abnormal Duplex findings in 31 patients led to angiography and revision in 13 cases. Four revised grafts failed, while nine remained patent at follow-up 1-12 months later. Ten (56%) of 18 non-revised bypasses with abnormal Duplex findings failed within 9 months compared to 1 (1%) of 76 bypasses with a normal velocity profile (p < 0.00001). In conclusion, Ultrasound Duplex scanning with spectral analysis provides valuable information concerning haemodynamics of infrainguinal vein bypasses and identifies grafts at risk of thrombosis. Inclusion of low resistance index (< 0.75) as an additional criteria for detection of stenoses appears to improve the sensitivity of Duplex scanning.

Aged↗

PubMed1990

[Neurologic complications in connection with the surgical treatment of 577 cases of carotid artery stenosis].

During the period January 1982 till June 1988, 536 patients underwent 577 carotid thrombendartectomies in the Department of Vascular Surgery RK in the University Hospital in Copenhagen. Preoperatively, 270 patients (47%) had experienced transient ischaemic attacks (TIA), 247 (43%) had experienced stroke (APC) and 19 (3%) had non-focal symptoms while 41 (7%) had asymptomatic stenoses. Postoperatively, 17 (2.9%) patients developed TIA, 22 (3.8%) developed slight neurological symptoms and 40 (7%) had more severe neurological complications and six of these (1%) died. None of the patients died from other causes during the first month. The frequency of complications had no relationship to the preoperative focal symptoms, but in patients with non-focal symptoms this was 37%. The degree of stenosis of the contralateral internal carotid artery (ICA) was correlated positively with the occurrence of severe neurological complications which were observed in 5% without contralateral ICA changes, in 7% with stenoses and in 20% with contralateral ICA occlusion. Patients with cerebral infarction developed complications significantly more frequently (20%) than patients with normal CT scans. The risk was also found to be increased in cases with a high pressure gradient across the stenosis and low pressure peripherally in the occluded artery (stump pressure). Follow-up examination of the 73 patients with complications on average 39 months after operation revealed that 37 patients (6.4%) had severe neurological symptoms resulting either from the operation or subsequent APC; seven patients required complete nursing care (1.2%) and 17 patients died during the period of observation. On follow-up examination, 15 patients had been occupationally active for at least 1.5 years.

Adult↗

PubMed1990

Eight to ten years follow-up after carotid endarterectomy: clinical evaluation and Doppler examination of patients operated on between 1978-1980.

Follow-up information was obtained on 185 patients who consecutively underwent carotid endarterectomy eight to ten years previously. Doppler ultrasound examination was performed in 59 patients who were still alive and living within 100 miles of the hospital. Using lifetable analysis, the annual rate of focal strokes was estimated to be 2% and 1.5% on the operated and the contralateral, non-operated carotid artery, respectively. Doppler examination revealed 48% re-stenoses, including 14% occlusion and 15% greater than 50% stenosis. However, there was no association between the occurrence of restenosis and the development of symptoms, perhaps with the exception of internal carotid artery occlusion, which is not an accepted indication for carotid endarterectomy. Together with recent data from the literature, these observations challenge the indication for reoperative carotid surgery.

Carotid Arteries↗

PubMed1990

Doppler waveform analysis in evaluation of occlusive arterial disease in the lower limb: comparison with distal blood pressure measurement and arteriography.

Three Doppler waveform parameters were related to ankle/brachial systolic pressure (A/B) index and angiography in 75 patients with lower limb arterial occlusive disease (AOD). Doppler signals were obtained from ankle arteries, and following spectral analysis pulse rise time (PRT), systolic width (SW) and pulsatility index (PI) were calculated. All three waveform parameters were significantly correlated with A/B index, and a 20% reduction could be predicted with an accuracy of 93 to 80% (corrected for chance, kappa, 81 to 52%). A significant correlation was also found between the three Doppler parameters and the angiographic assessment, i.e. the non-diseased, single- and multisegmentally diseased limbs, however, the accuracy in diagnosing angiographic stenoses was not as good as when pressure measurement was used for reference. Thirteen of the patients had high ankle pressures despite significant angiographic stenoses, and generally the Doppler examination was normal in these cases. Considering the waveform parameters individually, PRT and SW demonstrated almost identical results when compared to pressure measurement as well as angiography, whereas PI seemed clearly inferior. It is concluded that simple Doppler waveform parameters may accurately predict the haemodynamic significance of proximal AOD.

Angiography↗

PubMed1990

Carotid artery disease and low cerebral perfusion pressure: symptomatology, operative risk and outcome.

Direct internal carotid artery blood pressure measurements in patients undergoing carotid endarterectomy identified 49 patients, among 239 consecutive cases (21%), who had a reduction in perfusion pressure of 20% or more. The clinical history, objective findings and angiographic data were compared with those of a control group of a further 49 patients selected from the remaining patients operated on over the same period. The two groups were compared for short- and long-term outcome of surgery. We were unable to delineate a symptomatic neurological profile that identified patients with low perfusion pressures. Surgery in patients with low perfusion pressures seemed to be associated with an increased complication rate (12% versus 4%), although this was not statistically significant. Definite postoperative improvements in persisting neurological deficits were observed only in one patient. Long-term results were equal in the two groups with an annual stroke risk of 3%.

Adult↗

PubMed1989

[Referrals for carotid surgery during the period 1977-1986. The referral pattern for patients with carotid stenosis in the catchment region of the University Hospital in Copenhagen, assessed during a 10-year period].

Although carotid endarterectomy has been carried out for over 30 years, there are as yet no investigations which prove the value of this form of treatment with certainty. Attitudes to carotid surgery also vary greatly. The authors have assessed this variation during the period 1977-1986 on the basis of the lists of patients admitted to the Department of Vascular Surgery in the University Hospital. Patients from Funen and Jutland were excluded from the material because endarterectomy is also carried out in hospitals in these regions. A total of 720 patients from two extensive municipalities and six counties were admitted. During the period involved, increase in the number of referrals and also in the number of operations carried out occurred until 1984. After this, and in accordance with the global more restrictive attitudes, fewer patients were referred. Great regional variations were found as 8-10 as many patients per 100,000 inhabitants between 50 and 70 years were referred from the Municipality of Copenhagen as from the county which referred fewest patients. It is concluded that there are considerable differences in the treatment of patients with carotid stenosis within the catchment region of the University Hospital in Copenhagen.

Aged↗

PubMed1989

Real time B-mode mapping of the greater saphenous vein.

Real time ultrasound mapping of the greater saphenous vein (GSV) was performed in 30 consecutive patients admitted for in situ femoro-crural revascularisation. The overall accuracy in predicting the adequacy of the GSV for in situ bypass was 90%. The predictive value of finding the vein usable was 96%, whereas the predictive value of judging the vein inadequate was 50%. The scanning procedure provided morphologic information about the GSVs, including size, tributaries, varicosities, and double segments, which may prevent unnecessary dissection and may further shorten the duration of surgery. In our opinion the technique is sufficiently accurate to replace phlebography for the routine preoperative assessment of GSV in patients considered for in situ bypass. Veins judged inadequate at scanning, however, should be further evaluated.

Adult↗