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Biomedical subjects

T V Schroeder

Publications and source records attributed to T V Schroeder.

At least 37 records · Page 2Linked to original sources
PubMed2001

Screening for aortoiliac lesions by visual interpretation of the common femoral Doppler waveform.

OBJECTIVE: to study the accuracy of simple visual interpretation of the common femoral artery Doppler waveform for screening the aorto-iliac segment for significant occlusive disease. DESIGN: prospective and semi-blinded study. Material ninety-four consecutive and elective patients having arteriography due to chronic lower limb ischaemia, presenting symptoms of severe claudication (23%), ischaemic rest pain (34%) or ischaemic skin lesions (43%). METHODS: one day prior to conventional arteriography a Doppler waveform was obtained in the common femoral artery. Based on visual interpretation, the waveforms were immediately categorised as normal or abnormal. Comparison with single plane arteriography with respect to significant aorto-iliac occlusive disease was undertaken. RESULTS: visual Doppler waveform interpretation had a sensitivity of 98% (95% CI: 90-100%), a specificity of 81% (CI: 67-90%), a positive predictive value of 86% (CI: 75-93%) and a negative predictive value of 97% (CI: 86-100%) for prediction of significant aorto-iliac occlusive disease using conventional arteriography as the gold standard. The kappa value for the agreement between Doppler waveform interpretation and arteriography was 0.81 (0.68-0.93), representing very good agreement. CONCLUSION: a normal common femoral Doppler waveform can safely exclude significant upstream aorto-iliac lesions and is a useful timesaving screening tool in the busy vascular laboratory. The method is well tolerated, easy to perform and requires no additional equipment.

Adult↗
PubMed2001

Peripheral vascular surgery and magnetic resonance arteriography--a review.

OBJECTIVES: to review the current status of lower limb MRA. DESIGN: a literature review based predominantly on a MEDLINE database search of English-language publications from January 1991 to October 2000. MATERIALS AND METHODS: twenty-eight articles, concerning non-enhanced MRA (13), gadolinium-enhanced MRA (14) or both (1), met the predefined requirement for quality. Results gadolinium-enhanced MRA (CE-MRA) seems to be more accurate, quicker and associated with fewer problems than non-enhanced (TOF) MRA. TOF-MRA has a sensitivity and specificity of 93% (range 64-100%) and 88% (range 57-100%) respectively, and CE-MRA presents values of 96% (range 71-100%) and 96% (63-100%), respectively, using conventional arteriography as the gold standard. Some articles report a substantial incidence of runoff vessels suitable for distal bypass visible on MRA but invisible on conventional arteriography. Gadolinium contrast is given intravenously and is generally well tolerated and has no known nephrotoxicity. CONCLUSION: CE-MRA is accurate compared to conventional arteriography, has the potential to increase the limb salvage rate for selected patients, is non-invasive and well tolerated.

Arterial Occlusive Diseases↗
PubMed2001

Spiral computed tomographic imaging related to computerized ultrasonographic images of carotid plaque morphology and histology.

OBJECTIVE: Echolucency of carotid atherosclerotic plaques, as evaluated by computerized B-mode ultrasonographic images, has been associated with an increased incidence of brain infarcts on cerebral computed tomographic scans. We tested the hypotheses that characterization of carotid plaques on spiral computed tomographic images correlates with that on computerized B-mode ultrasonographic images and that spiral computed tomographic imaging predicts the histomorphometric plaque content. METHODS: The study included 38 patients with neurologic symptoms and at least 50% stenosis of the ipsilateral carotid artery. High-resolution B-mode ultrasonographic images and spiral computed tomographic images of carotid plaques were computer processed to yield a quantitative measure, the gray scale level of the plaque. RESULTS: The mean Hounsfield value for spiral computed tomographic images correlated with the gray scale median for B-mode ultrasonographic images (univariate linear regression analysis: r = 0.45; P = .01) and the histologic content of calcification in the plaque (r = 0.34; P = .04) but not with lipid, hemorrhage, or fibrous tissue in the plaque. CONCLUSIONS: Spiral computed tomographic imaging seems to correlate with B-mode ultrasonographic imaging for showing plaque characteristics. Spiral computed tomographic attenuation was also correlated with the amount of calcification noted on histologic examination but not with lipid and hemorrhage, the components thought to characterize vulnerable, rupture-prone plaques.

Carotid Arteries↗
PubMed2001

Intravascular ultrasound for iliac artery imaging. Clinical review.

IVUS is able to produce trans-sectional images of the iliac arteries at a high resolution. The three layered appearance of the arterial wall can be visualized. In the atherosclerotic diseased artery calcified plaques can be discerned from non-calcified plaques, and the distribution of the plaque-eccentric or concentric-can be determined. IVUS seems to be superior to arteriography in quantifying the degree of stenosis, being able to relate the luminal area to the mediabounded area at the same site of the artery. The discrepancy between IVUS and arteriography is even greater when evaluating residualstenosis after PTA. Structures such as rupture, intimal flaps and dissection are better visualized with IVUS. In stenotic iliac arteries IVUS has been able to evaluate the effect of PTA and stenting and relating the effect to the morphology of the plaque. IVUS measurements seem to be important predictors of the patency of iliac PTA. The ability of IVUS to evaluate the adaptation of stents to the arterial wall makes it particularly suited as a control procedure for the deployment of endovascular stented grafts. Finally IVUS has the ability to disclose insufficiency of endarterecomy, by visualizing remaining intraluminal material.

Angioplasty, Balloon↗
PubMed2000

[Variation of Doppler ultrasonography of carotid arteries].

The variation of ultrasound examination of the carotid arteries performed at two different hospitals was examined by retrospective analysis. Eighty-one patients were primarily examined by ultrasound at their local hospital on the suspicion of carotid stenosis. Following referral, they underwent a further scanning at the Dept. of Vascular Surgery, Rigshospitalet. Results for 143 carotid arteries were available for comparison. The overall agreement between the two examinations was only 59%. In nine of 40 (22%) cases an originally diagnosed minor stenosis was found to be significant and 3/19 (16%) with shown occlusion were found to be patent at the later examination. In order to draw clinical conclusions validation of each individual laboratory performing ultrasound examination of extracranial cervical arteries is necessary.

Carotid Arteries↗
PubMed2000

[Problem-based learning in medical education].

Problem Based Learning (PBL) has not yet been instituted systematically at medical schools in Denmark. We therefore introduced the method in a 10th term course in internal medicine and surgery, eighteen months before graduation, and evaluated the experience after two terms with a total of 93 students and 15 tutors. Compared with traditional education such as bed-side clinics and lectures etc., PBL was the preferred method by 67% of the students, while 28% found the methods equally good and only 2% discredited PBL. The main advantage of PBL was ascribed to motivation and activation, the students finding themselves as being part of the problem-solving situation. The tutors estimated PBL highly when teaching clinical coping strategies, stressing the need for a realistic and appropriate setting. This experience supports the decision to introduce PBL throughout the new medical curriculum in Copenhagen.

Curriculum↗
PubMed2000

The clinical importance and prediction of steal following femoro-femoral cross-over bypass: study of the donor iliac artery by intravascular ultrasound, arteriography, duplex scanning and pressure measurements.

OBJECTIVES: to evaluate the clinical significance of the steal phenomenon following femoro-femoral bypass, and whether the addition of intravascular ultrasound (IVUS) to the established examinations of the donor iliac artery can improve the prediction of patients who will develop steal. DESIGN: prospective study. MATERIAL AND METHODS: twenty-eight patients, aged 73 (50-81) years, scheduled for femoro-femoral bypass surgery in the period from 1994 to 1997, had the donor iliac artery examined by single-plane arteriography, duplex scanning, IVUS and femoral-artery blood pressure measurements (FABP)+/-papaverine. Three patients were excluded due to simultaneous thromboendarterectomy (TEA) of the donor iliac artery. The clinical stage and the ankle-brachial index (ABPI) were measured pre-, postoperatively and prospectively 1, 6, 12 and 24 months after discharge. RESULTS: two patients developed clinical steal, while an additional five had a measurable (>0.1) decline in the donor ABPI postoperatively, but no symptoms (subclinical steal). The clinical stage of the donor limb did not deteriorate further during the follow-up period (median 8 months) in these seven patients. The decline in donor ABPI correlated with the FABP and the IVUS measurements, but not to duplex scanning or arteriography. FABP after papaverine injection and IVUS examination showed equal sensitivities and and specificities. CONCLUSION: a clinical steal phenomenon following femoro-femoral bypass surgery seems relatively uncommon, although a subclinical steal is more frequent. Both can be predicted by FABP or IVUS. Further follow-up is required to evaluate whether subclinical steal has any consequences in the long term.

Aged↗
PubMed2000

Can colonoscopy diagnose transmural ischaemic colitis after abdominal aortic surgery? An evidence-based approach.

OBJECTIVES: to assess the diagnostic value of colonoscopy in ischaemic colitis following abdominal aortic surgery, based on a literature review, and to introduce the concept of evidence-based medicine. METHOD: a review of the literature according to evidence-based principles was made by all doctors of our department. RESULTS: seven prospective non-randomised reports on routine colonoscopy after abdominal aortic surgery were found. None of the participants found all the reports, and the last was identified by the reviewer. CONCLUSIONS: Endoscopy may disclose ischaemic colitis, but cannot separate transmural from the clinically less important mucosal ischaemia. Endoscopy had no impact on mortality in any of the prospective series. The evidence-based conference was an inspiring teaching modality, and illustrated for the participants the difficulty in performing a targeted literature search.

Aorta, Abdominal↗
PubMed2000

Eversion carotid endarterectomy generates fewer microemboli than standard carotid endarterectomy.

OBJECTIVES: to test whether the occurrence of microembolism differed between eversion and standard carotid endarterectomy (CEA). DESIGN: prospective, non-randomised transcranial Doppler (TCD) monitoring study of 61 patients. MATERIALS AND METHODS: eversion CEA was performed in 27 and standard CEA in 34 patients. Surgery was performed under general anaesthesia. Three (5%) patients had a shunt inserted based on continuous EEG monitoring. Continuous middle cerebral artery TCD monitoring (EME, TC-4040) was performed intraoperatively and for 45 min postoperatively on day 1, day 2-3, day 4-5 and after 3 months. Unidirectional signals lasting >25 ms, having intensities of >9 dB were considered to represent embolic events. RESULTS: intraoperative embolic events were detected in 50 (93%) of 54 patients in whom successful intraoperative TCD monitoring was achieved. Events occurred most frequently immediately following clamp release (85%), without difference between the two techniques. Embolic events were encountered postoperatively in four (15%) and 16 (48%) patients having eversion and standard CEA, respectively (p< 0.02). Four patients developed new neurological symptoms equally distributed between eversion and standard CEA. Two (3%) deficits were permanent and two transient. The patency of the carotid bifurcation was confirmed in all instances with duplex scanning. CONCLUSION: we identified a surprisingly high number of postoperative embolic events as detected with transcranial Doppler in patients who had undergone carotid surgery using standard endarterectomy, as compared to patients who underwent eversion endarterectomy. Whether this difference has any clinical implication has yet to be proved.

Aged↗
PubMed2000

Association of sex with patency of femorodistal bypass grafts.

OBJECTIVE: There is evidence for superior patency in infra-inguinal bypass procedures in men compared to women. A large, prospectively planned series was investigated in order to confirm this finding and to determine the origin of this difference in outcome. METHODS: Patients underwent femorodistal bypass surgery and a prospectively planned 12-month follow-up. Outcomes in male and female patients were compared and investigated for associations with characteristics of the patients and the surgical procedures. RESULTS: A total of 517 patients received femorodistal bypass grafts, including 424 vein grafts and 93 prosthetic and vein-prosthetic composite grafts. Patency was confirmed to be higher in male than in female patients (56% vs. 42%, p=0.005). Fewer male patients received prosthetic or composite grafts (21% vs. 33%, p=0.005), but the difference in patency was evident only in patients receiving vein grafts. Female patients were smaller, included fewer smokers (p<0.001) and had worse symptoms (p=0.03), but none of these characteristics explained the difference in outcome. Patency in vein grafts was associated with graft diameter (p=0.004), but graft diameter was not significantly associated with sex (p=0.09) or with body size. CONCLUSIONS: It was confirmed that patency of femorodistal bypasses is significantly higher in males than females. None of the factors investigated here explain this difference, but the greater use of prosthetic and composite grafts in female patients suggests that poorer vein quality should be investigated as a possible source of the inferior outcome in female patients.

Aged↗
PubMed2000

Incidence of stenoses in femorodistal bypass vein grafts in a multicentre study.

OBJECTIVES: To establish the incidence of graft stenosis in a large population of patients undergoing femorodistal bypass procedures and to investigate the differences in incidence between individual surgical centres and other subpopulations. PATIENTS AND METHODS: A total of 277 patients with femorodistal bypasses underwent duplex scanning of vein grafts for 12 months for the detection of graft stenoses. A standard definition of a significant stenosis was used in all twenty participating centres. RESULTS: Overall stenosis rate was 27%. Stenoses were more common in composite vein grafts (43%) than in single segment vein grafts (25%) p=0.05. Stenoses were more common in female patients (38%) than males (22%) p=0.02. Stenosis rates in individual centres entering more than 20 patients varied from 9% to 56%. In a multiple regression analysis only aspirin use, sex and centre were significant factors predicting the likelihood of graft stenosis. CONCLUSION: Female patients, those taking aspirin and patients with composite vein grafts appear to be more at risk of graft stenosis, but this does not fully explain wide variations in the incidence of stenoses reported by individual centres.

Adult↗
PubMed1999

[Causes of need for reoperation following surgery for varicose veins in Denmark].

In a surgical varicose vein practice 509 patients who had suffered recurrent varicose veins following surgery in other institutions were traced. The causes of recurrences were identified in a retrospective analysis and related to the source of primary treatment: in hospital treatment (n = 290), surgical practice (n = 56) or another varicose vein specialist (n = 104). A significant difference was noted between the three institutions in the use of saphenofemoral resection (78%, 63% and 97%) as well as greater saphenous vein stripping (44%, 14% and 0%). Lack of or insufficiently performed saphenofemoral surgery were identified as contributing to saphenofemoral insufficiency in 40% and 43% of patients primarily treated in hospital and in surgical practice, respectively, but only in 14% of those treated by a varicose vein specialist (p < 0.001). Primary sapheno-popliteal resection had been used equally infrequently (11%, 13% and 16%, respectively) and was equally frequently insufficiently performed (66%, 57% and 41%). This retrospective investigation concludes that insufficient varicose vein surgery is a major contributor to recurrences, particularly when primary surgery is performed in hospital or in surgical practice, as opposed to in a varicose vein practice. These results warrant a reorganisation of varicose vein surgery in Denmark.

Adult↗