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Graft occlusion: failure of graft surveillance?
S18
Abstracts
examined retrospectively using angiography as the gold standard. The results were graded according to the degree of concordance between the duplex and angiogram. All examinations were carried out by dedicated vascular Radiologists. Results: Duplex scanning correctly diagnosed the site and extent of the atheromatous disease in 37 out of 41 patients, giving a positive predictive value of 0.9 for significant disease above the inguinal ligament and in 45 out of 49 patients below the inguinal ligament, giving a positive predictive value of 0.92. Duplex results became inaccurate above and below the inguinal ligament when there was multisegment disease. Inaccuracy occurred when there was multiphasic flow in the vessels examined despite the presence of significant disease or when there was a series of sub significant stenoses or significant multisegment disease. Conclusion: Using the waveform and velocity of the blood within the common femoral artery to diagnose significant disease above the inguinal ligament has limitations, in particular when there is also disease below the inguinal ligament. Errors may arise above and below the inguinal ligament when there is a series of sub significant stenoses or if there is multisegment disease. Lower limb arterial duplex is an effective test for detecting single site disease but it can miss significant disease above the inguinal ligament when there is multisegment involvement. Duplex ultrasound is the gold standard in infrainguinal graft surveillance Irvine C.; McGrath C.; Morgan M.; Lewis D.; Jones A.; Murphy P.; Baird R.; Lamont P. Departments of Surgery, Medical Physics, and Radiology, Bristol Royal Infirmary, Bristol BS2 8HW UK, UK Postoperative infrainguinal bypass graft surveillance programmes are widely practised. Most programmes utilise noninvasive duplex scanning but diagnosis of graft abnormalities requires angiography. Some patients exhibit progressive duplex flow abnormalities on graft surveillance that do not correlate with angiographic assessment. From February 1993 to May 1996, 158 patients have attended post-operative infrainguinal bypass graft surveillance for a minimum of 6 weeks and a mean of 68 weeks (6 – 144 weeks). Two thirds of patients have undergone bypass grafting with vein and one third with prosthetic material. Fourty seven patients with graft stenoses were identified by duplex. Angiography was performed in all but two patients. Agreement between duplex and angiography occurred in 32 patients. In 13 patients duplex identified persisting flow abnormalities in whom arteriography could not identify a stenosis. Seven patients remain asymptomatic with a persisting duplex abnormality. The remaining six patients all exhibited disease progression on duplex and surgical intervention has revealed significant stenoses in all of these patients (retained valve cusps in 4). Duplex surveillance of infrainguinal bypass grafts screens patients to identify ‘at risk’ grafts and compliments invasive angiography by providing measurements of blood haemodynamics. In some patients with progressive duplex abnormalities angiography is no longer the gold standard.
Graft occlusion: failure of graft surveillance? Brown A.; Khaw K.-T. Department of Radiology, St. George’s Hospital, London, UK The purpose of a graft surveillance programme is to diagnose potential haemodynamic problems within grafts, so that appropriate intervention can occur before graft occlusion. Over a 32 month period 99 patients with 131 grafts (3 axillo-femoral, 17 crossover and 80 infrainguinal grafts) were scanned with colour duplex at 6 weeks, 3, 6, 9, 12, 18, 24 months and then yearly. Abnormal scans are discussed at the vascular meeting weekly and angiography should be performed if appropriate within 2 weeks. Follow-up was 1–32 months with a mean of 11.4 months. One hundred and one (77%) grafts remain patent, 39 (30%) having had 51 interventions engendered by graft surveillance. Despite the programme, 40 graft occlusions occurred in 30 (23%) grafts, eight occluding twice and one occluding three times (with at least 2 months patency between occlusions in the same graft). Occlusion occurred although a graft problem was predicted in 26/40 (65%). 1. One (2.5%) refused intervention 2. Three (7.5%) failed to attend 3. Four (10%) with abnormality could not be treated 4. Five (12.5%) occluded despite intervention 5. Six (15%) with duplex abnormality which was not brought to the attention of the vascular surgeons 6. Seven (17.5%) occluded while waiting for intervention (9 days – 4 months, mean 4 weeks)In 14 – 40 (35%) in whom it was not predicted 7. Six (15%) occlusions occurred without duplex warning. Two occurred in the same graft 8. Eight (20%) were never entered in the graft surveillance programme Twenty one to 40 (52.5%) of these graft occlusions (5, 6, 8 above) were therefore potentially avoidable and due to a failure of implementation of the programme. Lysis/thrombectomy was carried out on 31 of the 40 occlusions in 22 grafts but only 5 – 22 grafts remain patent after 13 months (mean FU 4.2 months) and two of these are failing. If graft surveillance is to succeed, it is essential that there is proper implementation of the graft surveillance protocol. Accuracy of colour flow duplex scanning in selection of patients for lower limb endovascular therapy Dhanjil S.; Ramaswami G.; Griffin M.; Nicolaides A. Purpose: In spite of the widespread use of colour flow duplex imaging (CFDI) for the diagnosis of cerebrovascular disease, it is still not widely accepted for the diagnosis of lower limb arterial disease. The purpose of this study was first to determine the accuracy of CFDI in comparison with angiography (DSA) which is the established ‘gold standard’ in the diagnosis of lower limb arterial disease and its potential for selecting patients for endovascular therapy. Method: 75 patients with claudication having angiography as part of their investigation were recruited. All these patients underwent CFD scanning and the results were compared with the angiograms by an independent observer. The results were used to select patients for endovascular therapy and this was again compared with angiograms.
Abstracts
examined retrospectively using angiography as the gold standard. The results were graded according to the degree of concordance between the duplex and angiogram. All examinations were carried out by dedicated vascular Radiologists. Results: Duplex scanning correctly diagnosed the site and extent of the atheromatous disease in 37 out of 41 patients, giving a positive predictive value of 0.9 for significant disease above the inguinal ligament and in 45 out of 49 patients below the inguinal ligament, giving a positive predictive value of 0.92. Duplex results became inaccurate above and below the inguinal ligament when there was multisegment disease. Inaccuracy occurred when there was multiphasic flow in the vessels examined despite the presence of significant disease or when there was a series of sub significant stenoses or significant multisegment disease. Conclusion: Using the waveform and velocity of the blood within the common femoral artery to diagnose significant disease above the inguinal ligament has limitations, in particular when there is also disease below the inguinal ligament. Errors may arise above and below the inguinal ligament when there is a series of sub significant stenoses or if there is multisegment disease. Lower limb arterial duplex is an effective test for detecting single site disease but it can miss significant disease above the inguinal ligament when there is multisegment involvement. Duplex ultrasound is the gold standard in infrainguinal graft surveillance Irvine C.; McGrath C.; Morgan M.; Lewis D.; Jones A.; Murphy P.; Baird R.; Lamont P. Departments of Surgery, Medical Physics, and Radiology, Bristol Royal Infirmary, Bristol BS2 8HW UK, UK Postoperative infrainguinal bypass graft surveillance programmes are widely practised. Most programmes utilise noninvasive duplex scanning but diagnosis of graft abnormalities requires angiography. Some patients exhibit progressive duplex flow abnormalities on graft surveillance that do not correlate with angiographic assessment. From February 1993 to May 1996, 158 patients have attended post-operative infrainguinal bypass graft surveillance for a minimum of 6 weeks and a mean of 68 weeks (6 – 144 weeks). Two thirds of patients have undergone bypass grafting with vein and one third with prosthetic material. Fourty seven patients with graft stenoses were identified by duplex. Angiography was performed in all but two patients. Agreement between duplex and angiography occurred in 32 patients. In 13 patients duplex identified persisting flow abnormalities in whom arteriography could not identify a stenosis. Seven patients remain asymptomatic with a persisting duplex abnormality. The remaining six patients all exhibited disease progression on duplex and surgical intervention has revealed significant stenoses in all of these patients (retained valve cusps in 4). Duplex surveillance of infrainguinal bypass grafts screens patients to identify ‘at risk’ grafts and compliments invasive angiography by providing measurements of blood haemodynamics. In some patients with progressive duplex abnormalities angiography is no longer the gold standard.
Graft occlusion: failure of graft surveillance? Brown A.; Khaw K.-T. Department of Radiology, St. George’s Hospital, London, UK The purpose of a graft surveillance programme is to diagnose potential haemodynamic problems within grafts, so that appropriate intervention can occur before graft occlusion. Over a 32 month period 99 patients with 131 grafts (3 axillo-femoral, 17 crossover and 80 infrainguinal grafts) were scanned with colour duplex at 6 weeks, 3, 6, 9, 12, 18, 24 months and then yearly. Abnormal scans are discussed at the vascular meeting weekly and angiography should be performed if appropriate within 2 weeks. Follow-up was 1–32 months with a mean of 11.4 months. One hundred and one (77%) grafts remain patent, 39 (30%) having had 51 interventions engendered by graft surveillance. Despite the programme, 40 graft occlusions occurred in 30 (23%) grafts, eight occluding twice and one occluding three times (with at least 2 months patency between occlusions in the same graft). Occlusion occurred although a graft problem was predicted in 26/40 (65%). 1. One (2.5%) refused intervention 2. Three (7.5%) failed to attend 3. Four (10%) with abnormality could not be treated 4. Five (12.5%) occluded despite intervention 5. Six (15%) with duplex abnormality which was not brought to the attention of the vascular surgeons 6. Seven (17.5%) occluded while waiting for intervention (9 days – 4 months, mean 4 weeks)In 14 – 40 (35%) in whom it was not predicted 7. Six (15%) occlusions occurred without duplex warning. Two occurred in the same graft 8. Eight (20%) were never entered in the graft surveillance programme Twenty one to 40 (52.5%) of these graft occlusions (5, 6, 8 above) were therefore potentially avoidable and due to a failure of implementation of the programme. Lysis/thrombectomy was carried out on 31 of the 40 occlusions in 22 grafts but only 5 – 22 grafts remain patent after 13 months (mean FU 4.2 months) and two of these are failing. If graft surveillance is to succeed, it is essential that there is proper implementation of the graft surveillance protocol. Accuracy of colour flow duplex scanning in selection of patients for lower limb endovascular therapy Dhanjil S.; Ramaswami G.; Griffin M.; Nicolaides A. Purpose: In spite of the widespread use of colour flow duplex imaging (CFDI) for the diagnosis of cerebrovascular disease, it is still not widely accepted for the diagnosis of lower limb arterial disease. The purpose of this study was first to determine the accuracy of CFDI in comparison with angiography (DSA) which is the established ‘gold standard’ in the diagnosis of lower limb arterial disease and its potential for selecting patients for endovascular therapy. Method: 75 patients with claudication having angiography as part of their investigation were recruited. All these patients underwent CFD scanning and the results were compared with the angiograms by an independent observer. The results were used to select patients for endovascular therapy and this was again compared with angiograms.