Biomedical subjects

C Teeuwen

Publications and source records attributed to C Teeuwen.

6 recordsLinked to original sources

PubMed1993

How can the assessment of the hemodynamic significance of aortoiliac arterial stenosis by duplex scanning be improved? A comparative study with intraarterial pressure measurement.

PURPOSE: The current diagnostic criteria used to assess the severity of stenoses in the aortoiliac arteries by duplex scanning are mainly based on information related to changes in cross-sectional area and are flow independent. Consequently, duplex scanning fails to detect approximately one quarter of hemodynamically significant aortoiliac lesions compared with intraarterial pressure measurements. The aim of this study is to improve the assessment of the hemodynamic significance of aortoiliac lesions by duplex scanning. METHODS: A prospective study in 60 patients was performed in which duplex scanning at rest was compared with intraarterial pressure measurements before and after the administration of papaverine. A simplified Bernoulli equation was used to calculate pressure gradients across stenoses (delta PBern). Two flow-related parameters, the increase in peak systolic velocity (delta PSV) across the stenosis and the end-diastolic velocity at the site of the stenosis, were also measured and compared with intraarterial pressure measurements. RESULTS: delta PBern and delta PSV showed a sensitivity and specificity of 81% and 88%, respectively, for the detection of hemodynamically significant lesions at rest. However, delta PBern could often not give an accurate calculation of the pressure gradient. Receiver operator characteristic analysis showed that a cut-off level for delta PSV in the range of 1.4 to 1.5 m/s was best able to detect significant lesions at rest. The end-diastolic velocity parameter had a limited diagnostic value. CONCLUSION: Although useful in clinical decision making, delta PBern often could not give an accurate calculation of the pressure gradient. delta PSV is a simple and practical spectral analysis parameter to differentiate between significant and insignificant stenoses. This parameter also has the potential to detect hemodynamically less critical lesions if duplex scanning is performed under conditions of increased flow. Further evaluation is needed.

Aorta, Abdominal↗

PubMed1991

Value of duplex scanning compared with angiography and pressure measurement in the assessment of aortoiliac arterial lesions.

To detect haemodynamically significant lesions in the aortoiliac arteries, invasive tests such as angiography and intra-arterial pressure measurement (IAPM) are considered valuable diagnostic tools. The value of duplex scanning as a direct non-invasive examination technique was prospectively compared with intra-arterial digital subtraction angiography (IADSA) and IAPM at rest, and after the administration of papaverine in 60 patients. Excellent agreement, as assessed by the kappa statistic, was shown between duplex scanning and IADSA (kappa = 0.81). A fair agreement was shown between duplex scanning and IAPM (kappa = 0.63), and between IADSA and IAPM (kappa = 0.63). Duplex scanning and IADSA both missed some less haemodynamically critical lesions if IAPM was considered the 'gold standard'. It is concluded that duplex scanning detects haemodynamically significant lesions as effectively as angiography and so may be considered a new and valuable diagnostic tool. IAPM remains necessary to detect some lesions of borderline haemodynamic significance. However, with future developments, duplex scanning has the potential to replace the need even for IAPM.

Angiography, Digital Subtraction↗

PubMed1991

Spectral analysis criteria in duplex scanning of aortoiliac and femoropopliteal arterial disease.

To validate the use of duplex scanning in the detection of lesions in the aortoiliac and femoropopliteal arteries, duplex scanning was prospectively compared to intra-arterial digital subtraction angiography in 61 patients with peripheral atherosclerotic disease. Based on a peak systolic velocity ratio greater than or equal to 2.5 or the absence of a Doppler signal, the overall sensitivity and specificity to detect lesions of greater than or equal to 50% diameter reduction was 84% and 96%, although some segments in the femoropopliteal arteries showed a sensitivity of only 60%-70%. Occlusions were detected with an overall sensitivity of 92% and specificity of 99%. The existence of a bi/triphasic Doppler signal, a window in the systolic spectral waveform and an end diastolic velocity greater than or equal to 60 cm/s has additional value in further grading of stenoses. This study shows that duplex scanning is highly comparable to angiography in the detection greater than or equal to 50% diameter reducing lesions in the aortoiliac arteries. Further evaluation is needed for the femoropopliteal arteries.

Angiography, Digital Subtraction↗

PubMed1989

The potential of duplex scanning to replace aorto-iliac and femoro-popliteal angiography.

The ability of duplex scanning to assess haemodynamically significant lesions in the aorto-iliac and femoro-popliteal arteries was studied. Duplex scanning was prospectively and independently compared to intra-arterial digital subtraction angiography (ia. DSA) of the aorto-iliac and femoro-popliteal arteries and intra-arterial pressure measurements of the aorto-iliac tract before and after the administration of papaverine. In 40 patients 629 arterial segments were evaluated. A greater than 150% increase in peak systolic velocity had a sensitivity of 92% and a specificity of 98% in detecting greater than 50% diameter reducing lesions in the aorto-iliac arteries as compared to ia. DSA. The numbers for the femoro-popliteal arteries are 88% and 98% respectively. Detection of occlusion in the aorto-iliac arteries had a sensitivity and specificity of 100% and in the femoro-popliteal arteries 90% and 100% respectively. There was a poorer correlation between intra-arterial pressure measurements and duplex scanning or ia. DSA as compared to the correlation between ia. DSA and duplex scanning. Retrospective spectral analysis showed that an end diastolic velocity (EDV) of greater than 40 cm/s seems to be a valuable parameter to differentiate between 50% to 74% and 75% to 99% diameter reduction. It is concluded that duplex scanning can reliably differentiate between haemodynamically significant and insignificant lesions in the aorto-iliac and femoro-popliteal arteries and has the potential to replace angiography.

Angiography↗

PubMed1989

Clinically unsuspected complications of arterial surgery shown by post-operative digital subtraction angiography.

Intravenous digital subtraction angiography was performed within 20 days of 678 vascular reconstructions as a routine post-operative evaluation. After 339 carotid endarterectomies, 34 patients showed a stenosis of greater than 30% and six occlusions were seen. In 157 patients after aortic aneurysm repair, we found five anastomotic aneurysms and seven stenoses of greater than 30%. After aortic bypass surgery, 77 patients were evaluated and nine stenoses were found; no anastomotic aneurysms were seen. In 105 patients with femoro-distal bypass procedures, occlusion was reported in 11 cases and stenosis in 13 cases. One patient had two anastomotic aneurysms. To summarize, major abnormalities were present in 81 cases (12.7%) and consisted of 59 stenoses of greater than 30%, 17 occlusions and six patients with anastomotic aneurysms. Most of these were unexpected and were reason for more critical follow-up or re-operation.

Aorta, Abdominal↗

PubMed1988

Benefits of carotid patching: a randomized study.

Advocates of carotid artery patching claim a reduced incidence of recurrent stenosis after endarterectomy. A prospective study was undertaken to determine its value with random selection between primary closure and saphenous vein patching. A consecutive series of 129 carotid endarterectomies was evaluated by duplex scanning at 3, 6, and 12 months after operation. Intravenous digital subtraction angiography (DSA) was performed in the first postoperative days for control of the surgical technique and after 1 year to serve as a reference for the duplex scanning. Sixty-two patients were selected to have primary closure and 67 were chosen for the patching technique. Both groups were identical with regard to risk factors (mean age 63 years, 74% were men, 57% had hypertension, 41% had coronary disease, 37% had peripheral arterial disease, and 9% had diabetes mellitus), side of operation (55% left), symptoms (18% were asymptomatic), and postoperative DSA (81% were normal, 17% had residual lesions, and 2% had occlusions). A complete 1-year follow-up was obtained in 105 cases (81%); duplex scanning showed recurrent stenosis of more than 50% in 12 cases (11%). This was significantly higher after primary closure (10 of 48 patients = 21%) compared with patch closure (2 of 57 = 3.5%; p = 0.006) and also in women (6 of 25 = 24%) compared with men (6 of 80 = 7.5%; p = 0.03). Recurrent stenosis was present in 6 of 11 women with primary closure (55%), 4 of 37 men with primary closure (11%), 2 of 43 men with patching (5%), and none of 14 women with patch closure (0%).(ABSTRACT TRUNCATED AT 250 WORDS)

Angiography↗