This thesis evaluated the efficacy of elective abdominal aortic aneurysm repair. The first part of this thesis evaluated the presumed long-term survival differences of endovascular aneurysm repair ... Show moreThis thesis evaluated the efficacy of elective abdominal aortic aneurysm repair. The first part of this thesis evaluated the presumed long-term survival differences of endovascular aneurysm repair (EVAR) versus open repair. Thereby, it evaluated the impact of developments in AAA management (i.e. the introduction of EVAR and cardiovascular risk management) on the long-term life-expectancy after repair. The second part of this thesis focused on other outcomes important in the evaluation of AAA care. It evaluated the presumed long-term cost difference of EVAR and open repair. In addition, it investigated how the patient perspective is currently embedded in AAA research.The five main conclusions of this thesis are that I) long-term (relative) survival between open versus endovascular aneurysm repair is equal; II) AAA patients remain a persistently high long-term (10-year) excess mortality after elective repair, with no change in mortality rates over the past 25 years; III) women have a notably higher short-and long-term mortality; IV) endovascular and open repair are considered cost equivalent; V) and the evaluation of the patient perspective/quality of life of AAA patients needs improvement. Show less
Genderen, O.S. van; Wissen, R.C. van; Hamming, J.F.; Schaik, J. van; Vorst, J.R. van der 2023
Purpose: To describe the concept of aortic elastic deformation (ED) measurement using duplex ultrasonography (DUS) as a tool for detection of high aneurysm sac pressure following endovascular... Show morePurpose: To describe the concept of aortic elastic deformation (ED) measurement using duplex ultrasonography (DUS) as a tool for detection of high aneurysm sac pressure following endovascular aortic repair (EVAR). Technique: High aneurysm sac pressure, with or without proven endoleak, will result in a less compressible aneurysm. Using the dual image function in B-mode of the DUS device and a standardized amount of applied probe pressure, ED can be measured. It is defined as the percentage of deformation of the aneurysm sac on probe pressure application. We hypothesize that less ED of the aneurysm sac can be related with high aneurysm sac pressure and possibly the presence of clinically relevant endoleak. In this note, we describe the technical details of the procedure and report on the applicability and results of ED measurements in the framework of aortic aneurysm and EVAR follow-up in a cohort of 109 patients. Conclusion: ED measurement is the first noninvasive pressure-based method in the quest to find a practical and reliable diagnostic tool to exclude high aneurysm sac pressure. In our patient cohort, patients with proven endoleak showed a smaller ED (less compressible), implying the presence of high aneurysm sac pressure. Further research should confirm whether ED measurement using DUS could reliably exclude endoleak after EVAR and further explore its potential for clinical application in EVAR follow-up. Clinical Impact For the first time, a simple, fast, and inexpensive diagnostic tool is presented in this study for detecting high sac pressure following EVAR. High sac pressure is typically caused by clinically significant endoleaks, which can have significant consequences. Currently, computed tomography scanning is the most common method used to identify and characterize endoleaks. However, measuring elastic deformation may potentially replace more invasive and expensive modalities, such as the computed tomography in the future. Show less
Bruijn, L.E.; Louhichi, J.; Veger, H.T.C.; Wever, J.J.; Dijk, L.C. van; Overhagen, H. van; ... ; Eps, R.G.S.S. van 2023
Purpose: Post-EVAR (endovascular aneurysm repair) aneurysm sac growth can be seen as therapy failure as it is a risk factor for post-EVAR aneurysm rupture. This study sought to identify... Show morePurpose: Post-EVAR (endovascular aneurysm repair) aneurysm sac growth can be seen as therapy failure as it is a risk factor for post-EVAR aneurysm rupture. This study sought to identify preoperative patient predictors for developing post-EVAR aneurysm sac growth. Material and Methods: A systematic review was conducted to select potential predictive preoperative factors for post-EVAR sac growth (including a total of 34.886 patients), which were evaluated by a retrospective single-center analysis of patients undergoing EVAR between 2009 and 2019 (N=247) with pre-EVAR computed tomography scans and at least 1 year follow-up. The primary study outcome was post-EVAR abdominal aortic aneurysm (AAA) sac enlargement (>= 5 mm diameter increase). Multivariate Cox regression and Kaplan-Meier survival curves were constructed. Results: Potential correlative factors for post-EVAR sac growth included in the cohort analysis were age, sex, anticoagulants, antiplatelets, renal insufficiency, anemia, low thrombocyte count, pulmonary comorbidities, aneurysm diameter, neck diameter, neck angle, neck length, configuration of intraluminal thrombus, common iliac artery diameter, the number of patent lumbar arteries, and a patent inferior mesenteric artery. Multivariate analysis showed that infrarenal neck angulation (hazard ratio, 1.014; confidence interval (CI), 1.001-1.026; p=0.034) and the number of patent lumbar arteries (hazard ratio, 1.340; CI, 1.131-1.588; p<0.001) were associated with post-EVAR growth. Difference in estimated freedom from post-EVAR sac growth for patients with >= 4 patent lumbar arteries versus <4 patent lumbar arteries became clear after 2 years: 88.5% versus 100%, respectively (p<0.001). Of note, 31% of the patients (n=51) with >= 4 patent lumbar arteries (n=167) developed post-EVAR sac growth. In our cohort, the median maximum AAA diameter was 57 mm (interquartile range [IQR] = 54-62) and the median postoperative follow-up time was 54 months (IQR = 34-79). In all, 23% (n=57) of the patients suffered from post-EVAR growth. The median time for post-EVAR growth was 37 months (IQR = 24-63). In 46 of the 57 post-EVAR growth cases (81%), an endoleak was observed; 2.4% (n=6) of the patients suffered from post-EVAR rupture. The total mortality in the cohort was 24% (n=60); 4% (n=10) was AAA related. Conclusions: This study showed that having 4 or more patent lumbar arteries is an important predictive factor for postoperative sac growth in patients undergoing EVAR. Clinical Impact This study strongly suggests that having 4 or more patent lumbar arteries should be included in preoperative counseling for EVAR, in conjunction to the instructions for use (IFU). Show less
Objective: To evaluate the impact of changes in elective Abdominal Aortic Aneurysm (AAA) management on life-expectancy of AAA patients.Background: Over the past decades AAA repair underwent... Show moreObjective: To evaluate the impact of changes in elective Abdominal Aortic Aneurysm (AAA) management on life-expectancy of AAA patients.Background: Over the past decades AAA repair underwent substantial changes, that is, the introduction of EVAR and implementation of intensified cardiovascular risk management. The question rises to what extent these changes improved longevity of AAA patients.Methods: National evaluation including all 12.907 (82.7% male) patients who underwent elective AAA repair between 2001 and 2015 in Sweden. The impact of changes in AAA management was established by a time-resolved analysis based on 3 timeframes: open repair dominated period (2001- 2004, n = 2483), transition period (2005-2011, n = 6230), and EVAR-first strategy period (2012-2015, n = 4194). Relative survival was used to quantify AAAassociated mortality, and to adjust for changes in life-expectancy.Results: Relative survival of electively treated AAA patients was stable and persistently compromised [4-year relative survival and 95% confidence interval: 0.87 (0.85- 0.89), 0.87 (0.86- 0.88), 0.89 (0.86- 0.91) for the 3 periods, respectively]. Particularly alarming is the severely compromised survival of female patients (4-year relative survival females 0.78, 0.80, 0.70 vs males 0.89, 0.89, 0.91, respectively). Cardiovascular mortality remained the main cause of death (51.0%, 47.2%, 47.9%) and the proportion cardiovascular disease over non-cardiovascular disease death was stable over time.Conclusions: Changes in elective AAA management reduced short-term mortality, but failed to improve the profound long-term survival disadvantage of AAA patients. The persistent high (cardiovascular) mortality calls for further intensification of cardiovascular risk management, and a critical appraisal of the basis for the excess mortality of AAA patients. Show less
Objective: The suggested high costs of endovascular aneurysm repair (EVAR) hamper the choice of insurance companies and financial regulators for EVAR as the primary option for elective abdominal... Show moreObjective: The suggested high costs of endovascular aneurysm repair (EVAR) hamper the choice of insurance companies and financial regulators for EVAR as the primary option for elective abdominal aortic aneurysm (AAA) repair. However, arguments used in this debate are impeded by time related aspects such as effect modification and the introduction of confounding by indication, and by asymmetric evaluation of outcomes. Therefore, a re-evaluation minimising the impact of these interferences was considered.Methods: A comparative analysis was performed evaluating a period of exclusive open repair (OR; 1998-2000) and a period of established EVAR (2010-2012). Data from four hospitals in The Netherlands were collected to estimate resource use. Actual costs were estimated by benchmark cost prices and a literature review. Costs are reported at 2019 prices. A break even approach, defining the costs for an endovascular device at which cost equivalence for EVAR and OR is achieved, was applied to cope with the large variation in endovascular device costs.Results: One hundred and eighty-six patients who underwent elective AAA repair between 1998 and 2000 (OR period) and 195 patients between 2010 and 2012 (EVAR period) were compared. Cost equivalence for OR and EVAR was reached at a break even price for an endovascular device of (sic)13 190. The main cost difference reflected the longer duration of hospital stay (ward and Intensive Care Unit) of OR ((sic)11 644). Re-intervention rates were similar for OR (24.2%) and EVAR (24.6%) (p = .92).Conclusion: Cost equivalence for EVAR and OR occurs at a device cost of (sic)13 000 for EVAR. Hence, for most routine repairs, EVAR is not costlier than OR until at least the five year follow up. Show less
Eps, R.G.S. van; Nemeth, B.; Mairuhu, R.T.A.; Wever, J.J.; Veger, H.T.C.; Overhagen, H. van; ... ; Knippenberg, B. 2017
Despite the rise of EVAR as treatment concept for abdominal aortic aneurysms during the last two decades, this concept is not flawless. For only a selection of the aneurysms is treatable with the... Show moreDespite the rise of EVAR as treatment concept for abdominal aortic aneurysms during the last two decades, this concept is not flawless. For only a selection of the aneurysms is treatable with the current EVAR grafts, due to unfavourable neck morphology and distal anatomy. Furthermore, many complications such as endoleaks do occur after EVAR, leading to stringent follow-up programs with many harmful imaging studies and a great number of secondary interventions. To overcome the anatomical limitations and potentially many of the procedure related complications, a novel treatment concept called Customized Aortic Repair (CAR) has been devised: a method of excluding the aortic aneurysm using endovascular techniques to inject a biocompatible elastomer into the aneurysm sac. The non-polymerised liquid elastomeric solution is used to fill the aneurysm sac around a balloon-catheter. After the in situ polymerisation and balloon deflation, an endoluminal mould with a patent lumen excludes the aneurysm sac. The potential of this treatment concept has been investigated in this thesis. Experiments described in this thesis taught us that filling the aneurysm sac with the elastomer in an in-vitro circulation model diminished wall movement and thereby wall-stress significantly, underlining the potential of the treatment concept. In the same circulation model, the elastomer was successfully used to exclude type II, III and IV endoleaks. Besides the several in-vitro experiments, the feasibility of the concept was tested in an in__vivo porcine experimental model (n=3). In these preliminary experiments, the aneurysms of all three pigs were successfully excluded with the elastomer. Dislodgement tests in a tensile testing machine showed that EVAR grafts (Excluder, Endurant and Anaconda), when inserted in a neck shorter then 15 mm, can be dislodged from a bovine artery sample easily. The largest force was needed to dislodge the Anaconda. When the area between the aneurysm model and the graft was filled with elastomer, the dislodgement force increased significantly with all grafts with 139-1016%. Filling the aneurysm sac with elastomer may prove to be a useful adjuvance to EVAR, diminishing the chance of graft dislodgement and type I endoleak. As the elastomer will be used endovascular, the direct contact with blood requires a low thrombogenicity of the elastomer to prevent occlusive thrombosis or embolization. The thrombogenicity of this new elastomer was tested in a validated ex- vivo model and compared to ePTFE to validate its feasibility in vivo. No significant difference in FPA production and platelet activation was observed between elastomer and ePTFE grafts (p>0.05). By scanning electron microscopy, numerous platelet aggregates were observed on the ePTFE grafts whereas just a few adhered platelets and no aggregates were observed in the elastomer grafts. This thesis underlines the large potential of the CAR-treatment concept, but also discusses its limitations. Show less
The technique of RSA to determine stent-graft migration and FRSA to study stent-graft dynamics are explained in further detail in CHAPTER 2. CHAPTER 3 and 4 concern the accuracy and feasibility of... Show moreThe technique of RSA to determine stent-graft migration and FRSA to study stent-graft dynamics are explained in further detail in CHAPTER 2. CHAPTER 3 and 4 concern the accuracy and feasibility of RSA to detect stent-graft migration in a static model and in a model with pulsatile motion. The results are compared to CT, the current clinical gold standard. RSA requires an aortic reference marker to detect stent-graft migration. A possible aortic reference marker is studied in CHAPTER 4 and 5. In CHAPTER 5, the feasibility of RSA in vivo is described. Furthermore, the position and the number of aortic reference markers required for accurate analysis needs to be clarified. These issues are discussed in CHAPTERS 5 and 6. Plain abdominal radiography is widely used as a low cost method to determine stent-graft migration. In CHAPTER 7, a study on the accuracy and, therefore, clinical applicability of plain abdominal radiography to detect stent-graft migration is described.In CHAPTER 8 the feasibility of FRSA is studied in a model and the method is validated for accuracy and precision. In CHAPTER 9, the first clinical introduction of this technique is reported. To conclude this thesis, the risk of radiation due to imaging for EVAR is evaluated in CHAPTER 10. Show less
Endovascular aneurysm repair (EVAR) is nowadays a globally applied treatment of abdominal aortic aneurysms (AAAs). The Achilles heel of EVAR is the incomplete seal of the aneurysm sac (endoleak) or... Show moreEndovascular aneurysm repair (EVAR) is nowadays a globally applied treatment of abdominal aortic aneurysms (AAAs). The Achilles heel of EVAR is the incomplete seal of the aneurysm sac (endoleak) or the persistence of significant pressure in the aneurysm sac without detectable endoleak (endotension). Therefore, follow-up is needed after EVAR. CT is considered the __gold-standard__ for the detection of endoleak and endotension. However, the CT has several drawbacks. Hence a new follow-up method is needed. This thesis contributes to the development of the rationale of aneurysm sac pressure (ASP) monitoring as follow-up. The aim of this thesis is to evaluate the possible pitfalls of ASP monitoring. The relationship between endoleak and ASP is not clear. Results of different studies are compared and the present knowledge about determinants of ASP is discussed. A model of the human circulation and thrombus analogues are developed and validated. The effect of the ASP measuring technique, the aneurysm sac thrombus, the sensor motion and the direction of ASP measurement on the measurement itself is evaluated. This thesis demonstrates that aneurysm sac pressure is not straightforward. A pressure trend seems more appropriate to follow than absolute aneurysm sac pressures. Show less
