Haemodynamics in axillobifemoral bypass grafts

This thesis is based on four publications on the subject of graft configuration and haemodynamics in axillobifemoral bypass grafts: 1. A clinical evaluation of 17 patients with axillobifemoral bypass graft operations, performed for various indications. Two important observations were made: an asymmetrical blood flow distribution between the two distal branches, in favour of the ipsilateral branch, and turbulent flow at the site of the bifurcation, as observed with duplex scanning. These observations, described in chapter 2, led to the development of a new design for an axillobifemoral bypass graft. 2. The second publication is a report of the results of an in-vitro study, performed to analyse the haemodynamical properties of three currently used axillobifemoral bypass graft configurations (with contralateral branches at angles of 30°,90° and 150° ) and the newly designed axillobifemoral bypass graft. The pressure drops across the four different axillobifemoral bypass bifurcation configurations under sinusoidal flow of a Newtonian fluid were analysed at four different flow rates at three different systemic mean pressures. This invitro experiment is described in chapter 3. 3. The third publication reports on the haemodynamical in-vivo properties of two different axillobifemoral bypass graft configurations (one with a contralateral branch at an angle of 90° and one with a symmetrical bifurcation and flowsplitter). This in-vivo study was conducted, because the in-vitro study was performed with a sinusoidal pulsatile flow of a Newtonian fluid, which has a different impact on flow profi1es and flow disturbances than the in-vivo physiological pulsatile flow of a non-Newtonian fluid, namely blood. All pressure losses across the bifurcation, ipsilateral and contralateral, were measured at different flow rates. The results are discussed in chapter 4. 4. In order to evaluate the clinical relevance of these findings, an international multicenter prospective randomized trial was conducted. The patency rates and clinical behaviour of the two different axillobifemoral bypass grafts, differing only in configuration of the bifurcation (one with a contralateral branch at an angle of 90° and one with a flowsplitter), were analysed in this trial. In 19 centers in Germany, Belgium, France and the Netherlands 117 patients were randomized, 59 receiving a prosthesis with a flowsplitter and 58 a prosthesis with a 90° bifurcation. Analysis of the results after 3 years with a mean follow up of 12 months is discussed in chapter 5

A prognostic model for amputation in critical lower limb ischemia

In a (negative) multicenter randomized trial on management for inoperable critical lower limb ischemia, comparing spinal cord stimulation and best medical treatment, a number of pre-defined factors were analyzed for prognostic value. We included a radiological arterial disease score, modified from the SVS/ISCVS runoff score. The purpose of this analysis was to evaluate clinical factors and commonly used circulatory measurements for prognostic modeling in patients with critical lower limb ischemia. We determined the incidence of amputation and its relation to various pre-defined risk factors. A total of 120 patients with critical limb ischemia were included in the study. The integrity of circulation in the affected limb was evaluated on five levels: suprainguinal, infrainguinal, popliteal, infrapopliteal and pedal. A total radiological arterial disease score was calculated from 1 (full integrity of circulation) to 20 (maximally compromised state). We used Cox regression analysis to quantify prognostic effects and differential treatment (predictive) effects. Major amputation occurred in 33% of the patients at 6 months and in 51% at 2 years. The presence of ischemic skin lesions and the radiological arterial disease score were independent prognostic factors for amputation. Patients with ulcerations or gangrene had a higher amputation risk (hazard ratio 2.38, p = 0.018 and 2.30, p = 0.036 respectively) as well as patients with a higher radiological arterial disease score (hazard ratio 1.17 per increment, p = 0.003). We did not observe significant interactions between prognostic factors and the effect of spinal cord stimulation. In conclusion, in patients with critical lower limb ischemia, the presence of ischemic skin lesions and the described radiological arterial disease score can be used to estimate amputation risk

Comparison of cost affecting parameters and costs of the 'closed' and 'open' in situ bypass technique

Objectives: The 'closed' in situ bypass results in a reduction of wound complications compared to the 'open' technique. This advantage is partly diminished by extra costs for the 'closed' procedure and a larger percentage of residual arteriovenous (AV)-fistulae. This aim of this study was to analyse costs related to 'closed' and 'open' procedures. Methods: The cost affecting parameters: (1) duration of operation; (2) length of hospital stay; and (3) number of treated residual AV-fistulae, were analysed in a randomised group of 73 patients (35 'closed' and 38 'open') in two centres. In addition, costs of the operation, nursing care and treatment of AV-fistulae were analysed. Results: The 'closed' and 'open' group showed a median duration of operation of 210 min (range 105-570) and 154 min (range 90-355) (p < 0.05), length of hospital stay of 16 days (range 5-51) and 25 days (range 12-65) (p < 0.01), and a percentage of patients treated for residual AV-fistulae of 40% and 5%, respectively (p < 0.01). The median 'closed' operation was US$798 more expensive than the 'open'. Median postoperative care was US$ 2664 less for the 'closed' group. Mean estimated costs for treatment of AV-fistulae was US$9 in the 'open' and US$ 167 in the 'closed' group. Conclusion: The 'closed' in situ vein bypass technique is cost-effective in comparison with the 'open' technique

Triage of patients with venous and lymphatic diseases during the COVID-19 pandemic – The Venous and Lymphatic Triage and Acuity Scale (VELTAS):: A consensus document of the International Union of Phlebology (UIP), Australasian College of Phlebology (ACP), American Vein and Lymphatic Society (AVLS), American Venous Forum (AVF), European College of Phlebology (ECoP), European Venous Forum (EVF), Interventional Radiology Society of Australasia (IRSA), Latin American Venous Forum, Pan-American Society of Phlebology and Lymphology and the Venous Association of India (VAI)

The coronavirus disease 2019 (COVID-19) global pandemic has resulted in diversion of healthcare resources to the management of patients infected with SARS-CoV-2 virus. Elective interventions and surgical procedures in most countries have been postponed and operating room resources have been diverted to manage the pandemic. The Venous and Lymphatic Triage and Acuity Scale was developed to provide an international standard to rationalise and harmonise the management of patients with venous and lymphatic disorders or vascular anomalies. Triage urgency was determined based on clinical assessment of urgency with which a patient would require medical treatment or surgical intervention. Clinical conditions were classified into six categories of: (1) venous thromboembolism (VTE), (2) chronic venous disease, (3) vascular anomalies, (4) venous trauma, (5) venous compression and (6) lymphatic disease. Triage urgency was categorised into four groups and individual conditions were allocated to each class of triage. These included (1) medical emergencies (requiring immediate attendance), example massive pulmonary embolism; (2) urgent (to be seen as soon as possible), example deep vein thrombosis; (3) semiurgent (to be attended to within 30-90 days), example highly symptomatic chronic venous disease, and (4) discretionary/nonurgent- (to be seen within 6-12 months), example chronic lymphoedema. Venous and Lymphatic Triage and Acuity Scale aims to standardise the triage of patients with venous and lymphatic disease or vascular anomalies by providing an international consensus-based classification of clinical categories and triage urgency. The scale may be used during pandemics such as the current COVID-19 crisis but may also be used as a general framework to classify urgency of the listed conditions