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H Sillesen

Publications and source records attributed to H Sillesen.

At least 37 records · Page 2Linked to original sources
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↗
PubMed1989

Haemodynamic evaluation of carotid artery disease.

Cerebral ischaemia in the region of an internal carotid artery (ICA) stenosis may be caused by embolism or cerebral hypoperfusion. A severe ICA stenosis may be well compensated by collateral blood supply, however, in some patients the capacity of the collateral blood supply is insufficient. Studies evaluating therapeutic modalities or natural history of carotid artery disease should therefore include a test capable of assessing cerebral haemodynamics. However, most studies, invasive as well as non-invasive, have focused on the ability of the test to diagnose the ICA lesions itself, rather than the haemodynamic changes induced by the stenosis. This paper reviews non-invasive methods for haemodynamic evaluation of carotid artery disease. Haemodynamic evaluation of ICA stenoses may be performed accurately by different techniques. Analysis of Doppler waveforms obtained distal to the ICA lesion and CBF reactivity tests may identify patients with severe reduction in ICA perfusion pressure. Periorbital Doppler examination and OPG identifies ICA lesions causing minor pressure gradients, however, they are unable to discriminate between minor and moderate to severe pressure reduction. Transcranial Doppler examination may prove to be useful in haemodynamic assessment of ICA stenoses, but, this remains to be evaluated. Presently, in addition to direct evaluation of the carotid arteries, we use a combination of periorbital Doppler examination and analysis of distal ICA waveforms. In cases of an ICA stenosis and orthograde flow any severe pressure reduction may be ruled out. In cases of inverted flow, analysis of distal ICA waveforms may identify patients with severe reduction in ICA perfusion pressure.

Brain Ischemia↗
PubMed1988

Quantitative assessment of carotid artery disease by continuous wave and pulsed multigated Doppler--prospective comparison with angiography.

We have evaluated the use of a Doppler system combining continuous wave (CW) and pulsed multigated Doppler (PD) for quantification of internal carotid artery (ICA) stenoses. The peak systolic frequency (PF), obtained with the CW technique was used for identification of lesions exceeding 50% stenosis. Thereafter, with the PD technique, the spectral broadening index (SBI) was calculated from a sample volume located in the area of highest forward velocity (PD), and this SBI was used to discriminate normal from diseased vessels. Results were compared with arterial digital subtraction angiography. For assessment of greater than or equal to 50% stenoses we obtained an overall accuracy of PF (CW) of 90%. The use of SBI (PD) for discriminating normal from diseased vessels resulted in an accuracy of 86% (sensitivity 93%, specificity 74%). The combination of CW and PD achieved an overall agreement of 77% (kappa = 0.676 +/- 0.053). It is concluded that the combination of CW and pulsed multigated Doppler is accurate in the diagnosis of even minor ICA stenoses. For exclusion of disease, imaging combined with flow information seems necessary.

Adult↗
PubMed1988

Changes in Doppler waveforms can predict pressure reduction across internal carotid artery stenoses.

Cerebral ischemia can result from either embolism or be due to hemodynamic failure. The purpose of this study was to evaluate whether Doppler waveforms, obtained distal to an internal carotid artery (ICA) stenosis, could predict the degree of hemodynamic compromise in terms of reduction in cerebral perfusion pressure. Forty-nine patients were examined consecutively with ultrasound Doppler prior to carotid endarterectomy. Pulsatility index (PI), pulse rise-time (RT), and systolic width (SW) were related to angiographic degree of stenosis and the ratio of distal ICA blood pressure to common carotid artery (CCA) blood pressure (ICA/CCA pressure ratio). The latter was determined during surgery. All three waveform parameters were significantly correlated with the ICA/CCA pressure ratio when calculated from the mean frequency curve (p less than 0.001). A reduction in ICA pressure of 20% could be predicted with an accuracy of 90-95%. Correlating the waveform parameters with arteriography was less convincing, reaching the level of statistical significance for PI only. ICA Doppler waveforms, obtained as distal in the neck as possible can accurately predict the degree of hemodynamic compromise. It is recommended as a simple adjunct to routine Doppler evaluation of carotid stenoses.

Angiography↗
PubMed1988

The haemodynamic value of external carotid artery collateral blood supply in carotid artery disease.

In the presence of severe obstruction of the internal carotid artery (ICA) blood supply to the ipsilateral hemisphere may be provided by collaterals. Whereas the circle of Willis in many cases makes a substantial contribution to cerebral perfusion, the value of collateral blood supply originating from the external carotid artery (ECA) is not clear. In thirty-five patients undergoing carotid endarterectomy (24 with proven external carotid artery collaterals) intra-arterial blood pressures were measured across the ICA stenosis, prior to endarterectomy. In order to evaluate the haemodynamic value of ECA collaterals, the distal ICA pressure was measured with and without the ECA clamped. In addition, volume blood flow in the common carotid artery was measured with and without the ECA clamped, before and after endarterectomy. No significant change in distal ICA pressure was observed when the ECA was clamped, whether or not external carotid artery collaterals had been demonstrated preoperatively. The greatest reduction in mean distal ICA pressure observed upon ECA clamping was 8 mmHg. However, this only occurred in three of 11 patients with a severe pressure reduction across the stenosis. ICA blood flow increased significantly following endarterectomy whereas ECA flow was reduced. This study indicates that ECA collaterals in most cases do not contribute substantially to cerebral perfusion. Endarterectomy of the ECA, in order to improve cerebral circulation, seems justified only in selected cases, where the distal ICA pressure has been shown to be severely reduced.

Adult↗