Pre-operative Patient Specific Flow Predictions to Improve Haemodialysis Arteriovenous Fistula Maturation (Shunt Simulation Study): A Randomised Controlled Trial.

OBJECTIVE: An arteriovenous fistula (AVF) needs to mature before it becomes suitable to cannulate for haemodialysis treatment. Maturation importantly depends on the post-operative flow increase. Unfortunately, 20-40% of AVFs fail to mature (FTM). A patient specific computational model that predicts immediate post-operative flow was developed, and it was hypothesised that providing information from this model for planning of fistula creation might reduce FTM rates. METHODS: A multicentre, randomised controlled trial in nine Dutch hospitals was conducted in which patients with renal failure who were referred for AVF creation, were recruited. Patients were randomly assigned (1:1) to the control or computer simulation group. Both groups underwent a work up, with physical and duplex ultrasonography (DUS) examination. In the simulation group the data from the DUS examination were used for model simulations, and based on the immediate post-operative flow prediction, the ideal AVF configuration was recommended. The primary endpoint was AVF maturation defined as an AVF flow ≥500 mL/min and a vein inner diameter of ≥4 mm six weeks post-operatively. The secondary endpoint was model performance (i.e. comparisons between measured and predicted flows, and (multivariable) regression analysis for maturation probability with accompanying area under the receiver operator characteristic curve [AUC]). RESULTS: A total of 236 patients were randomly assigned (116 in the control and 120 in the simulation group), of whom 205 (100 and 105 respectively) were analysed for the primary endpoint. There was no difference in FTM rates between the groups (29% and 32% respectively). Immediate post-operative flow prediction had an OR of 1.15 (1.06-1.26; p < .001) per 100 mL/min for maturation, and the accompanying AUC was 0.67 (0.59-0.75). CONCLUSION: Providing pre-operative patient specific flow simulations during surgical planning does not result in improved maturation rates. Further study is needed to improve the predictive power of these simulations in order to render the computational model an adjunct to surgical planning.

Endovascular vs. open repair of complicated acute type B aortic dissections.

Purpose : To assess the comparative effectiveness of thoracic endovascular aortic repair (TEVAR) vs. open surgical repair (OSR) of complicated acute type B aortic dissections (cABAD) using decision analysis. Methods : A decision analysis comparing TEVAR and OSR for cABAD included variables extracted from the best-available evidence. Main outcomes were quality-adjusted life years (QALYs), presented with the 95% credibility intervals (CI), and number of reinterventions over the remaining lifetime. Different clinical scenarios, including age, gender, and risk profile were analyzed. Parameter uncertainty was analyzed using probabilistic sensitivity analysis. Results : In the reference case, a cohort of 55-year-old men, TEVAR was preferred over OSR: 7.07 QALYs (95% CI 6.77 to 7.38) vs. 6.34 QALYs (95% CI 6.04 to 6.66) for OSR. The difference of 0.73 QALYs (95% CI 0.29 to 1.17) is equal to 8.5 months in perfect health. TEVAR was more effective in all analyzed cases and age groups. Perioperative mortality was the most important variable affecting the difference between OSR and TEVAR, followed by the relative risk and percentage of aortic-related complications. Total expected reinterventions were 0.43/patient (TEVAR) and 0.35/patient (OSR). Conclusion : The results of this decision model for the treatment of cABAD suggest that TEVAR is preferred over OSR. Although a higher number of reinterventions is expected, the total effectiveness of TEVAR is higher for all age groups. OSR should be reserved for patients whose aortic anatomy is unsuitable for endovascular repair.

A comparison of open and endovascular revascularization for chronic mesenteric ischemia in a clinical decision model.

OBJECTIVE: Open revascularization (OR) has been the treatment of choice for chronic mesenteric ischemia (CMI) for many years, but endovascular revascularization (EV) has been increasingly used with good short-term results. In this study, we evaluated the comparative effectiveness and cost-effectiveness of EV and OR in patients with CMI refractory to conservative management. METHODS: A Markov-state transition model was developed using TreeAge Pro 2012 (TreeAge Inc, Williamstown, Mass) to simulate a hypothetical cohort of 10,000 65-year-old female patients with CMI requiring treatment with either OR or EV. Data for the model, including perioperative and long-term overall mortality risks, disease-specific mortality risks, complications, and reintervention and patency rates, were retrieved from original studies and systematic reviews about CMI. Costs were analyzed with the 2013 Medicare database. Outcomes evaluated were quality-adjusted life-years (QALYs), costs from the health care perspective, and the incremental cost-effectiveness ratio. Extensive sensitivity analyses were performed and different clinical scenarios evaluated. Probabilistic sensitivity analysis was performed to assess robustness of the model. RESULTS: For a reference-case 65-year-old female patient with CMI and an average risk for operation, EV is preferred with 10.03 QALYs (95% credibility interval [CI], 9.76-10.29) vs 9.59 after OR (95% CI, 9.29-9.87). The difference is comparable to 5 months in perfect health: 0.44 QALY (95% CI, 0.13-0.76). For 65-year-old men, this was 8.71 QALYs (95% CI, 8.48-8.94) for EV vs 8.42 (95% CI, 8.14-8.63) for OR. Sensitivity analysis showed that for younger patients, EV results in a higher increase in QALYs compared with older patients. Total expected reinterventions per patient are 1.70 for EV vs 0.30 for OR. Total expected health care costs for the reference-case patient were $39,942 (95% CI, $28,509-$53,380) for OR and $38.217 (95% CI, $29,329-$48,309) for EV. For men, this was $39,375 (95% CI, $28,092-$52,853) for OR and $35,903 (95% CI, $27,685-$45,597) for EV. For patients younger than 60 years, EV is a more expensive treatment strategy compared with OR, but with an incremental cost-effectiveness ratio for EV of less than $60,000/QALY. For patients 60 years and older, EV dominated OR as preferential treatment because effectiveness was higher than for OR and costs were lower. CONCLUSIONS: The results of this decision analysis model suggest that EV is favored over OR for patients with CMI in all age groups. Although EV is associated with more expected reinterventions, EV appears to be cost-effective for all age groups.

A clinical decision model for selecting the most appropriate therapy for uncomplicated chronic dissections of the descending aorta.

OBJECTIVE: The optimal treatment for patients with uncomplicated chronic Stanford type B aortic dissections (chTBADs) is still matter of debate. The purpose of this study was to design a decision tool to guide the surgeon in determining the preferred treatment option. METHODS: A Markov decision-analysis model compared chTBAD patients treated with initial open surgical repair (OSR), thoracic endovascular aortic repair (TEVAR), and optimal medical therapy (OMT), followed during follow-up by OSR (OMT-OSR) or TEVAR (OMT-TEVAR), if indicated. Procedural risks, aortic growth and rupture rates, outcomes, and quality of life values were derived from the best available evidence in the literature. A chTBAD treatment strategy decision tool was developed, including the four key variables of age, sex, surgical risk, and maximum initial aortic diameter. Primary outcome was quality-adjusted life-years (QALYs). RESULTS: For the reference patient cohort, 55-year-old men with chTBAD with a maximum aortic diameter of 5.0 cm, medium risk for surgery, and a threshold for surgery of 6.0 cm during follow-up, OSR yielded higher QALYs, with 10.06 QALYs (95% credibility interval [CI], 9.52-10.56 QALYs) vs 9.92 QALYs (95% CI, 9.23-10.58 QALYs) after TEVAR and 9.64 QALYs (95% CI, 9.38-9.88 QALYs) and 9.40 QALYs (95% CI, 9.11-9.69 QALYs) for OMT-OSR and OMT-TEVAR. The difference between OSR and OMT-OSR was 0.42 QALYs (95% CI, 0.01-0.81 QALYs) and between TEVAR and OMT-TEVAR was 0.52 QALYs (95% CI, 0.04-0.68 QALYs). This showed that intervention is preferred over OMT. A change of the four variables resulted in a change of preferred treatment. In general, OSR was the preferred treatment in younger patients with a larger aortic diameter and in low-risk patients. TEVAR was preferred in elderly patients with large aortic diameter and if the aortic diameter threshold for repair decreased. OMT was the optimal therapy in high-risk patients, elderly patients, or in patients with small aortic diameters. CONCLUSIONS: This decision-analysis model shows that there is no "one-size-fits-all" treatment for uncomplicated chTBADs. For the reference patient cohort, intervention is preferred over OMT. Age is the most important deciding factor, followed by initial aortic diameter. Immediate OSR is the preferred treatment option in younger patients with a large initial aortic diameter and in low-risk patients. Immediate TEVAR is preferred in elderly patients with a large initial aortic diameter and in patients with a lower threshold for OSR. OMT should be considered in high-risk patients, in patients with small initial aortic diameters, and in patients aged >80 years, unless their initial aortic diameter is >5.5 cm. However, the differences in some patient groups are clinically insignificant, allowing a major role for patient preferences and hospital-specific considerations. This clinical decision model may guide chTBAD treatment.

Successful treatment of a proximal type I endoleak with HeliFX EndoAnchors.

We report the use of Aptus HeliFX EndoAnchors for endovascular treatment of a proximal type I endoleak after previous endovascular aneurysm repair (EVAR) of a ruptured abdominal aortic aneurysm. An 81-year-old man had been treated with EVAR after a ruptured 12 × 11 cm abdominal aortic aneurysm. Standard computed tomographic angiography follow-up demonstrated a proximal type I endoleak. Because of the highly angulated neck and close position of the endograft to the renal arteries, placement of a proximal extension cuff was prohibited; therefore, the endoleak was treated with an alternative approach using the Aptus HeliFX EndoAnchors. Nine EndoAnchors were successfully placed circumferentially on the proximal site of the endograft. This successfully treated the endoleak by excluding the aneurysm sac from the circulation. Computed tomographic angiography follow-up after 3 months showed no residual type I endoleak. This case shows that placement of EndoAnchors can serve as a viable treatment option for proximal type I endoleaks after failed EVAR.

Decision analysis model of open repair versus endovascular treatment in patients with asymptomatic popliteal artery aneurysms.

OBJECTIVE: Repair is indicated of asymptomatic popliteal artery aneurysms (aPAAs) that are >2 cm. Endovascular PAA repair with covered stents (stenting) is increasingly used. It is, however, unclear when an endovascular approach is preferred to traditional open repair with great saphenous vein bypass (GSVB). The goal of this study was to assess the treatment options for aPAAs using decision analysis. METHODS: A Markov model was developed and a hypothetic cohort of patients with aPAAs was analyzed. GSVB, stenting, and nonoperative management with optimal medical treatment (OMT) were compared. Operative mortality, patency rates, quality-of-life values, and costs were determined by comprehensive review of the best available evidence. The main outcome was quality-adjusted life-years (QALYs). Secondary outcomes were cost-effectiveness and number of reinterventions. RESULTS: For a 65-year-old male patient with a 2.0-cm aPAA and without significant comorbidities, probabilistic sensitivity analysis shows that intervention is preferred over OMT (5.77 QALYs, 95% credibility interval [CI], 5.43-6.11; OMT). GSVB treatment for this patient results in slightly higher QALYs than stent placement, with a predicted 8.43 QALYs (GSVB: 95% CI, 8.21-8.64) vs 8.07 QALYs (stenting: 95% CI, 7.84-8.29), a difference of 0.36 QALYs (95% CI, 0.14-0.58). Furthermore, costs are higher for stenting ($40,464; 95% CI, $34,814-$46,242) vs GSVB ($21,618; 95% CI, $15,932-$28,070), and more reinterventions are required after stenting (1.03 per patient) vs GSVB (0.52 per patient), making GSVB the preferred strategy for all outcomes considered. Stenting is preferred in patients who are at high risk for open repair (>6% 30-day mortality) or if the 5-year primary patency rates of stenting increase to 80%. For very old patients (>95 years) and patients with a very short life expectancy (<1.5 years), OMT yields higher QALYs. CONCLUSIONS: GSVB is the preferred treatment in 65-year-old patients with aPAAs for all outcomes considered. However, patients at high risk for open repair or without suitable vein should be considered as candidates for endovascular repair. Very elderly patients and patients with a short life expectancy are best treated with OMT. Further improvement of endovascular techniques that increase patency rates of endovascular stents could make this the preferred therapy for more patients in the future.

Surgical and anesthetic considerations for the endovascular treatment of ruptured descending thoracic aortic aneurysms.

PURPOSE OF REVIEW: Ruptured descending thoracic aortic aneurysm (rDTAA) is a life-threatening disease. In the last decade, thoracic endovascular aortic repair (TEVAR) has evolved as a viable option and is now considered the preferred treatment for rDTAAs. New opportunities as well as new challenges are faced by both the surgeon and the anesthesiologist. This review describes the impact of current developments and new modalities for the surgical and anesthetic management of rDTAAs. RECENT FINDINGS: A collaborative approach between the anesthesiologist and surgeon during critical moments such as induction, moment of aortic occlusion and placement of the aortic stent-graft is mandatory. Important issues to consider on preoperative imaging evaluation are correct sizing of the aortic stent-graft and localization of the artery of Adamkiewicz. Emergency TEVAR should preferentially be started under local anesthesia and could be switched to general anesthesia after stent placement. Patients should be kept in permissive hypotension preoperatively and during the intervention before stent-graft deployment and relative hypertension after deployment. The use of a proactive spinal cord protection protocol could decrease the risk of spinal cord ischemia and/or paraplegia and consists of permissive hypertension after stent deployment, cerebrospinal fluid drainage to maintain adequate spinal cord perfusion, relative hypothermia and possibly use of mannitol. SUMMARY: In order to improve outcomes of TEVAR for rDTAA, a close communication between the anesthesiologist and the surgeon and a thorough understanding of the events during the procedure is mandatory. The use of a proactive spinal cord protection protocol may decrease the rates of devastating spinal cord ischemia.

Thoracic endovascular aortic repair with the chimney graft technique.

OBJECTIVE: This study was conducted to provide insight into the safety, applicability, and outcomes of thoracic endovascular aortic repair (TEVAR) with the chimney graft technique. METHODS: Original data regarding the chimney technique in TEVAR in the emergent and elective setting were collected from MEDLINE, Embase, and Scopus databases. All variables were systematically extracted and included in a database. Patient and procedural characteristics, details, and outcomes were analyzed. RESULTS: In total, 94 patients with 101 chimney-stented aortic arch branches were analyzed, consisting of the brachiocephalic artery in 20, the left common carotid artery in 48, and the left subclavian artery in 33. Balloon-expandable stents were used in 36% and self-expandable stents in 64% for the aortic side branch. The interventions were elective in 72% and emergent in 28%. Technical success was achieved in 98% in elective and emergent settings combined. Endoleaks were described in 18%; with type Ia being most frequently reported in 6.4% overall and in 6.5% in the elective setting. Stroke was reported in 5.3% of the patients, of which 40% were fatal. The overall perioperative mortality was 3.2%. Median follow-up time was 11 months, and chimney stents remained patent in all patients. CONCLUSIONS: TEVAR with the chimney technique is a viable treatment option and may expand treatment strategies for patients with challenging thoracic aortic pathology and anatomy in the emergent and elective setting. Patency of the thoracic chimney stents appears to be good during short-term follow-up. Other complications, such as endoleak and stroke, deserve attention by future research to further improve treatment strategies and the prognosis of these patients.

A Giant Superior Mesenteric Artery Aneurysm Mimicking an Abdominal Aortic Aneurysm.

Superior mesenteric artery aneurysms are a rare clinical finding but can present with a wide range of symptoms. They are associated with a high risk of rupture, as well as high morbidity and mortality. We present a case of a 38-year-old female who presented with acute abdominal pain and a pulsatile palpable mass in the right epigastric region without other signs or symptoms.

Endoleaks after endovascular abdominal aortic aneurysm repair: what one needs to know.

PURPOSE OF REVIEW: To review the current state of diagnosis, treatment, and outcomes of the different types of endoleaks after endovascular abdominal aortic aneurysm repair (endovascular aneurysm repair, EVAR). RECENT FINDINGS: Endoleaks are the most frequent complication after EVAR, the most common indication for secondary interventions, and the most common cause of rupture after EVAR. Imaging is critical for detecting endoleaks. Type I and III endoleaks require urgent intervention to prevent aneurysm rupture. Intervention for other endoleaks or endotension is indicated if the aneurysm sac continues to grow during follow-up. The majority of endoleaks can be treated with endovascular techniques. Open surgical conversion may be considered if the risk of aneurysm rupture is high and if no endovascular options are available or if they have failed. SUMMARY: Endoleaks continue to be a challenge and this article discusses the different treatment options for endoleaks after EVAR. Long-term follow-up after EVAR is required to diagnose and treat endoleaks before they result in aneurysm rupture. The majority of endoleaks can be treated with endovascular techniques, although open surgical interventions may be required in selected patients.

Lower extremity limb salvage with cryoplasty: a single-center cohort study.

Endovascular techniques have been playing an increasing role in managing lower extremity chronic critical limb ischemia (CLI) in patients considered poor or non-candidates for surgical revascularization secondary to co-morbidities such as coronary artery disease, uncontrolled hypertension, diabetes mellitus or inadequate conduit. This study reviews our recent clinical experience in the treatment of peripheral artery disease solely using cryoplasty. A retrospective cohort study was performed. The cohort consisted of 88 patients who underwent lower extremity revascularization utilizing cryoplasty between December 2003 and August 2007. Indications for intervention included poor wound healing after forefoot amputation or persistent ulceration of the foot, disabling claudication and rest pain. Kaplan-Meier analysis was performed to assess salvage rates. One hundred twenty-six lesions were treated in 88 patients. Technical success rate was 97%. Limb salvage rates were 75 and 63% for patients with critical limbs ischemia after one and three years, respectively. A history of smoking was associated with a threefold increased risk of limb loss. In conclusion, endovascular management of lower extremity lesions with cryoplasty is an emerging and viable paradigm in the treatment of CLI in an attempt to preserve limbs and avoid major amputations.

Thoracic aortic pulsatility decreases during hypovolemic shock: implications for stent-graft sizing.

PURPOSE: To investigate the thoracic aortic pulsatility during hypovolemic shock in an experimental porcine model. METHODS: The circulating blood volume of 7 healthy Yorkshire pigs was gradually lowered until the subjects had lost 40% of their normal blood volume. Intravascular ultrasound was used to assess the aortic pulsatility in normovolemic and hypovolemic state at the level of the ascending and descending thoracic aorta. RESULTS: The mean aortic pulsatility at the level of the ascending aorta decreased from 15.9% ± 7.2% (range 6.3%-25.7%) in normovolemia to 6.2% ± 2.8% (range 2.9%-10.7%, p = 0.018) in hypovolemia. At the level of the descending thoracic aorta, the mean aortic pulsatility decreased from 8.7% ± 2.8% (range 4.4%-12.2%) at baseline to 5.6% ± 2.5% (range 1.5%-9.5%, p = 0.028) in hypovolemia. The maximum mean aortic diameter, obtained in cardiac systole, was significantly smaller as well at both evaluated levels during hypovolemic shock compared with the mean diameter in normovolemia. CONCLUSION: The thoracic aortic diameter and pulsatility decreased significantly during hypovolemic shock in this porcine model, most impressively at the level of the ascending aorta. Electrocardiographically-gated imaging may not be necessary for hypovolemic patients with acute aortic disease requiring endovascular repair because of the minimal aortic pulsatility.

The chimney procedure is an emergently available endovascular solution for visceral aortic aneurysm rupture.

A 79-year-old woman presented with a ruptured saccular thoracoabdominal aortic aneurysm involving the celiac and mesenteric artery. The patient was unfit for open surgical repair. A "chimney" procedure was performed, which involved placement of stents in the aortic side branches alongside the endograft. The patient underwent another chimney procedure 2 weeks later for a type I endoleak. Computed tomography angiography (CTA) at 1 and 6 months showed a good result with no endoleaks or graft migration. The chimney procedure provides an alternative for emergency patients unfit for open repair and has the advantage that stents can be used that are already available in most institutions.

Endograft collapse after thoracic endovascular aortic repair.

PURPOSE: To provide insight into the causes, timing, and optimal management of endograft collapse after thoracic endovascular aortic repair (TEVAR). METHODS: A comprehensive review was conducted of all published cases of endograft collapse after TEVAR identified using Medline, Cochrane Library Central, and EMBASE. In total, 32 articles describing 60 patients (45 men; mean age 40.6 ± 17.2 years, range 17-78) with endograft collapse were included. All data were extracted from the articles and systematically entered into a database for meta-analysis. RESULTS: In the 60 cases of endograft collapse, TEVAR had most commonly been applied to repair traumatic thoracic aortic injuries (39, 65%), followed by acute and chronic type B aortic dissections (9, 15%). The median time interval between TEVAR and diagnosis of endograft collapse was 15 days (range 1 day to 79 months). On average, the collapsed endografts were oversized by 26.7% ± 12.0% (range 8.3%-60.0%). Excessive oversizing was reported as the primary cause of endograft collapse in 20%, and a small radius of curvature of the aortic arch was responsible for 48% of the cases. The 30-day mortality was 8.3%, and the freedom from procedure-related death at 3 years after diagnosis of stent-graft collapse was 83.1% for asymptomatic patients compared with 72.7% for patients who had symptoms at diagnosis (p=0.029). CONCLUSION: Endograft collapse typically occurs shortly after TEVAR, most frequently after endovascular repair of traumatic aortic injury. A high level of suspicion for endograft collapse in the first month after TEVAR, as well as further improvement of current endovascular devices, may be required to improve the long-term outcomes of patients after TEVAR.

Mortality after hospital admission for ruptured abdominal aortic aneurysm.

BACKGROUND: The purpose of this study is to quantify age- and gender-specific mortality risks for patients hospitalized for ruptured abdominal aortic aneurysm (rAAA). METHODS: The mortality risks for 28-day, 1-year, and 5-year were derived from a retrospective nation-wide cohort study of patients who were first hospitalized for rAAA in 1997 or 2000, formed through linkage of the Hospital Discharge Register with the Dutch population register. The Hospital Discharge Register contains a record for each hospital admission, giving information about patient demographics and diagnosis. The population register contains information on patient demographics and the mortality status of all registered persons in The Netherlands. Relations between gender and mortality within specific age groups were assessed with chi-square tests. Associations between age, gender, comorbidities, and mortality were studied in multivariate analysis with Cox regression. RESULTS: A total of 1,463 patients hospitalized for rAAA were identified (86% males). Mean age was higher in women than in men (79 vs. 72 years; 95% CI of difference: 5.0-7.4). Mortality risks at 28-day, 1-year, and 5-year increased significantly with age (28-day: from 36 to 91% in men and 59 to 92% in women; 5-year: from 51 to 97% in men and 79 to 96% in women). In patients aged <80 years, mortality risks were significantly higher in women than in men. Age (HR: 1.04; 95% CI: 1.03-1.05), previous hospitalization for congestive heart failure (HR: 1.55; 95% CI: 1.06-2.26), and cerebrovascular disease (HR: 1.60; 95% CI: 1.16-2.21) were significant predictors of short- and long-term mortality. CONCLUSIONS: Mortality risks after hospitalization for rAAA clearly increase by age and are higher in women than in men in patients aged <80 years. Because of the major effect of age and gender, future studies should consider reporting absolute mortality risks stratified by age and gender, instead of simply presenting overall mortality risks.

Management of type A aortic dissections: a meta-analysis of the literature.

The authors reviewed all published series of type A iatrogenic aortic dissections and performed meta-analyses to investigate the management and outcomes of this complication. The majority of type A iatrogenic aortic dissections occurred during cardiac surgery, but the incidence of iatrogenic aortic dissection was considerably higher during thoracic endovascular aortic repair. Intraoperative diagnosis of iatrogenic aortic dissection was made in 69% of patients, and surgical repair of the dissection was performed in 88%. The overall in-hospital mortality was 38%, and the intraoperative diagnoses (odds ratio 0.35; p = 0.01) and surgical repairs (odds ratio 0.09; p = 0.001) were associated with reduced in-hospital mortality in univariate regression analysis.