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

Subfascial endoscopic ligation in the treatment of incompetent perforating veins

Objectives: To assess the technique of subfascial endoscopic ligation of incompetent perforatory veins by use of a mediastinoscope. Design: Prospective open clinic study. Setting: Two Departments of Surgery. Materials and Methods: Thirty-eight consecutive patients (40 legs) with recurrent or protracted venous ulceration of the lower leg were treated. Through a short, transverse incision of the skin and fascia in the proximal ⅓ of the lower leg a mediastinoscope (length 18 cm, diameter 12 mm) is inserted after which the perforating veins are ligated by haemoclips under direct vision. Main Results: All legs showed signs of incompetent perforating veins by clinical examination, confirmed with continuous wave ultrasonography and in 31 legs there was associated deep vein incompetence. Sixteen patients had active ulceration at the moment of operation and 22 had a history of recent or recurrent ulceration. One patient developed an inflammatory reaction at the wound and in two legs a subfascial infection occurred, necessitating surgical drainage. No postoperative mortality was seen. All 16 ulcers healed within 2 months (mean: 34 days; range: 21–55 days). During a mean follow-up of 3.9 (range: 2–5) years only one out of 38 patients (2.5%) developed a recurrent ulcer. Conclusions: Subfascial endoscopic ligation of incompetent perforating veins by use of a mediastinoscope is a relatively simple technique with a low postoperative complication rate and a low recurrent ulcer rate which makes it a valuable method for treating incompetent perforating veins

The value of pre-operative ultrasound mapping of the greater saphenous vein prior to 'closed' in situ bypass operations

Objective: The aim of this study was to test pre-operative ultrasound mapping for the detection of duplications and narrow vein segments of the greater saphenous vein (GSV) used as bypass for occlusive arterial disease surgery. Patients and methods: In 44 patients pre-operative ultrasound findings of duplications and lumen assessment of the GSV were compared to the per-operative findings. Results: In nine patients (20%) the pre-operative ultrasound examination showed a duplication. Pre-operative ultrasound had missed a duplication in two cases but had instead shown a narrow segment in both. The pre-operative ultrasound assessment of lumen diameter showed a narrow lumen segment in 10 of the 44 patients. In one patient a per-operatively narrow lumen had not been seen on pre-operative ultrasound. Conclusion: Pre-operative ultrasound mapping of the GSV is a sensitive tool for detection of duplications and narrow vein segments. Since these anatomical variations provide important information for the vascular surgeon, before performing a 'closed' in situ bypass operation, pre-operative vein mapping should be considered when planning such a procedure

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

Flow measurements in dialysis shunts: lack of agreement between conventional Doppler, CVI-Q, and ultrasound dilution

BACKGROUND: Measuring flow in dialysis shunts is recommended to predict imminent thrombosis. Multiple methods for measuring blood flow are in use. Numerous ultrasound protocols exist which determine volume flow using a conventional Doppler (CD) frequency shift analysis technique. All of these are subject to potentially large errors. Quantitative colour velocity index (CVI-Q) does not make use of the Doppler equation and is more precise in vitro. Ultrasound dilution (UD) measures access flow during dialysis in a non-operator-dependent way. The aim of the present study was to compare these three methods of measuring access flow in vivo for agreement with each other. METHODS: In 38 accesses flow was measured by CD, CVI-Q, and UD. All measurements were done during dialysis. Agreement was determined by intraclass correlation coefficient (ICC=R(i)) and Bland-Altman analysis. RESULTS: ICC between UD and CVI-Q was R(i)=0.56. ICC between UD and CD was R(i)=0.10, and ICC between CD and CVI-Q was R(i)=0.16. Bland-Altman analysis revealed a bias (mean difference) of -38 ml/min between UD and CVI-Q, a bias of 1129 ml/min between UD and CD, and a bias of 1167 ml/min between CVI-Q and CD. CONCLUSIONS: CD measurements did not agree with UD or CVI-Q much higher values were recorded with the former than with the latter two techniques. The agreement between UD and CVI-Q measurements is low but reasonable. Caution must be applied in comparing and interpreting values of access flow measured by different techniques

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) semi-urgent (to be attended to within 30–90 days), example highly symptomatic chronic venous disease, and (4) discretionary/non-urgent- (to be seen within 6–12 months), example chronic lymphoedema. Ven