Comparative corrosion behavior of three titanium alloy base materials and their welds in a simulated chimney environment.

This study investigates the corrosion behavior of titanium alloys (TA2, TC4, TB6) in a 3 % sulfuric acid flue gas environment using electrochemical tests and microscopic analyses (SEM/EDS, XRD, metallographic microscopy). Results show that TA2 base metal has lower corrosion resistance compared to its weld metal, while TC4 and TB6 exhibit opposite trends. Specifically, TC4 and TB6 base metals have lower corrosion current densities (0.9 and 0.5 µA/cm2) and higher corrosion potentials then their weld metals (1.93 and 2 µA/cm2). In contrast, TA2 base metal showed higher corrosion current density (2 µA/cm2) than its weld metal (0.35 µA/cm2) and HAZ metal (0.16 µA/cm2). Microscopic analyses reveal ß phase transitions in TC4 and TB6 weld areas, leading to larger grain sizes and reduced corrosion resistance. Conversely, TA2 retains finer grains post-welding, enhancing its corrosion resistance. These insights clarify weld corrosion effects and provide valuable guidance for industrial applications of titanium alloys, particularly in designing and maintaining titanium alloy chimneys.

Complex abdominal aortic aneurysms: a review of radiological and clinical assessment, endovascular interventions, and current evidence of management outcomes.

Endovascular aortic aneurysm repair (EVAR) is an established approach to treating abdominal aortic aneurysms, however, challenges arise when the aneurysm involves visceral branches with insufficient normal segment of the aorta to provide aneurysm seal without excluding those vessels. To overcome this, a range of technological developments and solutions have been proposed including fenestrated, branched, physician-modified stents, and chimney techniques. Understanding the currently available evidence for each option is essential to select the most suitable procedure for each patient. Overall, the evidence for fenestrated endovascular repair is the most comprehensive of these techniques and shows an early post-operative advantage over open surgical repair (OSR) but with a catch-up mortality in the mid-term period. In this review, we will describe these endovascular options, pre- and post-procedure radiological assessment and current evidence of outcomes.

The combination of iliac branch device with parallel stent graft to preserve bilateral internal iliac arteries in a patient with infrarenal abdominal aortic and bilateral common iliac artery aneurysm with short common iliac lengths: A case report.

Coexistent aneurysmal involvement of common iliac artery is frequently seen in patients with infrarenal abdominal aortic aneurysm. Bilateral iliac branch devices are an option to preserve bilateral internal iliac arteries in order to decrease the risk of buttock claudication. In Asian population, however, the aortoiliac lengths are commonly not adequate for bilateral iliac branch endoprosthesis. In this technical note, we use a novel hybrid technique to preserve bilateral internal iliac arteries in a patient without adequate aortoiliac length for bilateral iliac branch endoprosthesis. The right internal iliac artery is preserved with iliac branch endoprosthesis. The left internal iliac artery is preserved with cross-over chimney stent grafts which are deployed simultaneously with the parallel grafting of iliac extension from the contralateral gate to the right iliac branch endoprosthesis. Follow-up computed tomography and three-dimensional angiography showed complete aneurysm exclusion with flow preservation to bilateral internal iliac arteries.

Repair of parastomal hernias with the intraperitoneal funnel meshes IPST-R and IPST.

The treatment of parastomal hernias (PSH) represents a major challenge in hernia surgery. Various techniques have been reported with different outcomes in terms of complication and recurrence rates. The aim of this study is to share our initial experience with the implantation of the DynaMesh-IPST-R and -IPST, intraperitoneal funnel meshes made of polyvinylidene fluoride (PVDF). This is a retrospective observational cohort study of patients treated for PSH between March 2019 and April 2023 using the chimney technique with the intraperitoneal funnel meshes IPST-R or IPST. The primary outcome was recurrence and the secondary outcomes were intraoperative and postoperative complications, the latter assessed using the Clavien-Dindo classification. A total of 21 consecutive patients were treated with intraperitoneal PVDF funnel meshes, 17 with IPST-R and 4 with IPST. There were no intraoperative complications. Overall, no complications occurred in 61.9% (n = 12) of the patients. Major postoperative complications (defined as Clavien-Dindo ≥ 3b) were noted in four cases (19.0%). During the mean follow-up period of 21.6 (range 4.8-37.5) months, one patient (4.8%) had a recurrence. In conclusion, for the treatment of parastomal hernias, the implantation of IPST-R or IPST mesh has proven to be efficient, easy to handle, and very safe. In particular, the low recurrence rate of 4.8%, which is in line with the current literature, is convincing. However, a larger number of patients would improve the validity of the results.

Comparative Evaluation of the Short-Term Outcome of Different Endovascular Aortic Arch Procedures.

Objectives: There are several endovascular treatment options to treat aortic arch and thoracic aortic pathologies with custom-made or surgeon-modified aortic stent grafts. This study seeks to assess endovascular treatment methods for aortic arch and thoracic aortic pathologies with no acceptable proximal landing zone for standard thoracic endovascular aortic repair (TEVAR), comparing different treatment methods and evaluating technical success, intraoperative parameters and short-term outcomes. Methods: All patients undergoing elective or emergency endovascular treatment of aortic arch and thoracic aortic pathologies, with no acceptable landing zone for standard TEVAR, between 1 January 2010 and 31 March 2024, at the University Hospital Düsseldorf, Germany were included. An acceptable landing zone was defined as a minimum of 2 cm for sufficient sealing. All patients were not suitable for open surgery. Patients were categorized by an endovascular treatment method for a comprehensive comparison of pre-, intra- and postoperative variables. IBM SPSS29 was used for data analysis. Results: The patient cohort comprised 21 patients, predominantly males (81%), with an average age of 70.9 ± 9 years with no acceptable proximal landing zone for standard TEVAR procedure. The most treated aortic pathologies were penetrating aortic ulcers and chronic post-dissection aneurysms. Patients were sub-grouped according to the applied procedure as follows: five patients with chimney thoracic endovascular aortic repair (chTEVAR), seven patients with in situ fenestrated thoracic endovascular aortic repair (isfTEVAR), six patients with custom-made fenestrated thoracic endovascular aortic repair (cmfTEVAR) and three patients with custom-made branched thoracic endovascular aortic repair (cmbTEVAR). Emergency procedures involved two patients. There were significant differences in the total procedure and fluoroscopy time, as well as in contrast agent usage among the treatment groups. cmfTEVAR had the shortest total procedure time, while chTEVAR exhibited the highest contrast agent usage. The overall mortality rate among all procedures was 9.5% (two patients) and 4.7% for elective procedures, respectively. Deaths were associated with either retrograde type A dissection or stent graft infection. Both patients were treated with chTEVAR. There was one minor and one major stroke; these patients were treated with isfTEVAR. No endoleak occurred during any procedure. The reintervention rate for chTEVAR was 20% and 0% for all other procedures during the in-hospital stay. The patients who were treated with cmfTEVAR had no complications, the shortest operating and fluoroscopy time, and less contrast agent was needed in comparison with other treatment methods. Conclusions: Complex endovascular procedures of the aortic arch with custom-made or surgeon-modified aortic stent grafts offer a safe solution, with acceptable complication rates for patients who are not suitable for open aortic arch repair. In terms of procedure-related parameters and complication rates, a custom-made fenestrated TEVAR is potentially advantageous compared to the other endovascular techniques.

Comparison of chimney technique and single-branched stent graft in a cohort of patients with type B aortic dissections: a retrospective cohort study.

Background: Single-branched stent grafts and the chimney technique are widely used in the treatment of type B aortic dissection (TBAD). The main objective of this study was to compare the outcomes of single-branched stent grafts and the chimney technique in the treatment of TBAD. Methods: From January 2019 to December 2021, the retrospective cohort study contained a cohort of 91 patients with TBAD undergoing thoracic endovascular aortic repair (TEVAR) using single-branched stent grafts and the chimney technique. Group A included 55 patients treated with single-branched covered stents, and Group B included 36 patients treated with the chimney technique. We compared the effects of the procedures on peri-/post-operative outcomes between the two groups. The primary endpoint is clinical death, and the secondary endpoints include the patency of branch stents, the incidence of cerebral infarction, false lumen thrombosis, and the proportion of paraplegia. Results: For the baseline data, the two groups of patients show no differences in terms of age, gender, and associated symptoms. All procedures were successfully performed in both groups. The median follow-up period was 17.6 months (range, 10-34 months). During TEVAR, 5 (9.1%) type I endoleaks occurred in group A, and 11 (30.6%) occurred in group B (P<0.05). During follow-up, there were 2 cases (3.6%) of paraplegia and 1 case (1.8%) of cerebral infarction in Group A, while Group B had 1 case (2.8%) of paraplegia. Three patients in group B reported retrograde type A aortic dissection (RTAD), and 1 of them died (2.8%); however, there were no RTAD cases in group A. Complete thrombosis of the false lumen in the thoracic aorta was observed in 45.5% (25/55) of patients in group A and in 41.7% (15/36) in group B (P=0.72). No significant difference in the thrombosis-volume ratio in the whole false lumen was found during follow-up between group A (81.0%±2.9%) and group B (81.8%±2.6%; P=0.23). Conclusions: Branched stent grafts can be used in cases with insufficient proximal landing zones and reduce the occurrence of type 1 endoleak compared to the chimney technique. This may help to prevent RTAD. Further research, including more cases and longer follow-up periods, is needed to substantiate these results.

In vitro quantification of stent-graft behaviour during chimney thoracic endovascular aortic repair.

OBJECTIVE: To quantify dynamic gutter phenomena and endograft deformations during double chimney thoracic endovascular aortic repair (ch-TEVAR) in a physiological model of the thoracic aorta subjected to pulsatile haemodynamic conditions. METHODS: Two in vitro procedures revascularizing the brachiocephalic trunk and left common carotid artery were performed representing both balloon-expandable (BE, Ankura-BeGraft) and self-expandable (SE, Ankura-Viabahn) double ch-TEVAR configurations. Retrospectively gated computed tomography (CT) was used to evaluate endograft behaviour. Device interactions were characterised according to gutter volume, gutter surface deviation, and endograft deformation (D-ratio) at end-diastolic and peak-systolic aortic pressure. RESULTS: Use of BE chimney grafts resulted in three times total gutter volume compared to SE chimney grafts. Gutter volumes were observed to vary dynamically between the end-diastolic and peak-systolic phases of the cardiac cycle, with the most substantial change associated with the BE configuration. Chimney graft deformations were dependent on device type, with SE devices exhibiting up to twice the deformation as BE devices. When adjacent, SE chimney grafts were observed to support each other, and thus tended towards a more consistently circular shape. CONCLUSION: Gutter and chimney graft behaviour were dependent on device type, and exhibited both spatial and temporal variability. This study emphasises notable differences between BE and SE double ch-TEVAR configurations which should be considered when evaluating risk of endoleak. The findings reported here also support the use of gated CT to better identify device-related complications with ch-TEVAR, and can be used in the design of next generation devices.

Coronary Risk in Transcatheter Aortic Valve Replacement, Overview of Data, Challenges, and Best Practices.

Coronary artery obstruction is a rare complication of transcatheter aortic valve replacement (TAVR). This risk increases in TAVR-valve-in-valve procedure. Several anatomic risk factors were described in many studies to identify the predictive elements of coronary artery occlusion on computed tomography cardiac scan. Rescue percutaneous coronary intervention was the first approach described to treat this complication with a high mortality rate. Later on, preventive chimney stenting technique was evaluated and results showed that is a safe and effective strategy but it leads to a difficult coronary access later. New preventive techniques are being evaluated recently (Basilica and Shorctut).

Hemodynamic analysis of thoracic endovascular aortic repair with left subclavian artery reconstructed by chimney stent.

OBJECTIVES: The purpose of this study was to investigate the hemodynamic consequences of thoracic endovascular aortic repair which reconstructed left subclavian artery by chimney stent (ch-TEVAR). METHODS: Two patients who underwent thoracic endovascular aortic repair (TEVAR) and left subclavian artery (LSA) reconstruction using chimney stents were selected. Preoperative and postoperative CTA images were collected to reconstruct hemodynamic models for comparing and analyzing blood pressure, blood flow velocity, and wall shear stress in the aortic arch and its major branches. Concurrently, morphological alterations and position of chimney stent were also assessed. RESULTS: After the reconstruction of LSA in ch-TEVAR, no endoleak was seen, but the stent in LSA was compressed. The blood flow velocity of the LSA increased and disordered, the pressure was reduced, and the WSS was increased. Even more, there were a large amount of turbulence found in the LSA of one case, and its LSA was blocked. CONCLUSION: Chimney stent reduces the occurrence of endoleak due to its excellent deformation ability, but the compressed stent has a greater impact on the hemodynamics of LSA and eventually leads to LSA occlusion; in order to keep the LSA unobstructed, it is necessary to pay attention to the position of the chimney stent and keep it straight and do not fold or twist. Chimney stent has little influence on the aortic arch and the rest of the aortic arch branches.

Successful chimney endovascular aortic repair with reconstruction of three visceral branches for huge saccular juxtarenal abdominal aortic aneurysm after trans-thoracoabdominal esophagectomy.

BACKGROUND: Conventional graft replacement for a juxtarenal abdominal aortic aneurysm (JRAAA) remains challenging for high-risk patients since it often requires the reconstruction of some visceral arteries. CASE PRESENTATION: A 76-year-old woman was diagnosed with an 87 × 48 mm saccular JRAAA. Open graft replacement was contraindicated because of frailty and a past history of trans-thoracoabdominal esophagectomy. Chimney endovascular aortic repair (ChEVAR) with three chimney endografts was successfully performed without any endoleaks, and each visceral circulation was kept intact. The patient was discharged uneventfully on postoperative day 8. Significant shrinkage of the aneurysmal sac and preservation of flow through each chimney graft were observed on computed tomography 6 months postoperatively, with no significant increase in serum creatinine levels on laboratory testing. CONCLUSIONS: ChEVAR can be a useful surgical option instead of conventional operations, especially for high-risk cases.

Estimated greenhouse gas emissions in the Mbalmayo thermal power plant between 2016-2020 using the genetic-Gaussian algorithm coupling.

The greenhouse gas (GHG) emissions inventories in our context result from the production of electricity from fuel oil at the Mbalmayo thermal power plant between 2016 and 2020. Our study area is located in the Central Cameroon region. The empirical method of the second level of industrialisation was applied to estimate GHG emissions and the application of the genetic algorithm-Gaussian (GA-Gaussian) coupling method was used to optimise the estimation of GHG emissions. Our work is of an experimental nature and aims to estimate the quantities of GHG produced by the Mbalmayo thermal power plant during its operation. The search for the best objective function using genetic algorithms is designed to bring us closer to the best concentration, and the Gaussian model is used to estimate the concentration level. The results obtained show that the average monthly emissions in kilograms (kg) of GHGs from the Mbalmayo thermal power plant are: 526 kg for carbon dioxide (CO2), 971.41 kg for methane (CH4) and 309.41 kg for nitrous oxide (N2O), for an average monthly production of 6058.12 kWh of energy. Evaluation of the stack height shows that increasing the stack height helps to reduce local GHG concentrations. According to the Cameroonian standards published in 2021, the limit concentrations of GHGs remain below 30 mg/m3 for CO2 and 200 µg/m3 for N2O, while for CH4 we reach the limit value of 60 µg/m3. These results will enable the authorities to take appropriate measures to reduce GHG concentrations.

Do strength of zirconia-abutment-interfaces depend on cement, zirconia type and titanium abutment dimensions?

OBJECTIVES: Part 1 of this study investigates the influence of zirconia types, chimney heights, and gingival heights on the strength of the zirconia-abutment-interface. Part 2 extends the analysis to include adhesive brands and macro-retentions. METHODS: In Part 1, the study utilized three zirconia types (700 MPa, 1000 MPa, 1200 MPa) to fabricate 234 screw-retained zirconia crowns with varying chimney heights (3.5 mm, 4.1 mm, 5 mm) and gingival heights (0.65 mm, 1.2 mm, 3 mm) of the titanium abutments. All adherend surfaces underwent sandblasting with aluminum oxide before cementation with a specific resin cement. In Part 2, the investigation of 240 screw-retained zirconia crowns focused on a single zirconia type (1000 MPa) with chimney heights of 3.5 mm and 5 mm and a gingival height of 0.65 mm of the titanium abutments, cemented with three different resin cements. All adherent surfaces underwent sandblasting with aluminum oxide before cementation, whereas 120 out of 240 abutments received additional macro retentions. Storage in water at 37 °C for 24 h preceded the tensile test. RESULTS: The study revealed a substantial impact of chimney height and zirconia type on the bond strength of the zirconia-abutment-interface. Neither adhesive brands nor macro retentions significantly impacted the bond strength. Fracture incidence was significantly influenced by gingival height and zirconia type in part 1, whereas in part 2 smaller chimney heights correlated with a higher fracture incidence. SIGNIFICANCE: This study contributes insights into the complex interplay of factors influencing the zirconia-abutment-interface. The results provide a foundation for refining clinical approaches, emphasizing the importance of chimney height and zirconia type in achieving successful anterior gap implant restorations.

Integrating physical experiments with computational fluid dynamics to transform mosque minarets into efficient solar chimneys.

This study explores the potential of repurposing mosque minarets as solar chimneys in hot arid regions to facilitate natural ventilation and diminish the reliance on energy-intensive cooling systems. Originating as a means to call the faithful to prayer, minarets have become iconic landmarks within Islamic cities. This research focuses on Cairo, Egypt, as a representative hot arid environment. The paper traces the evolution of the minaret, underscoring the variations in form that influence the experimental design. The investigation proceeded in two stages: the construction of physical mosque models with variably positioned minarets for laboratory testing, ensuring standardized measurements, followed by computational fluid dynamics (CFD) simulations for comparison. Findings indicate that mosque minarets can be effectively adapted for passive ventilation, with their performance significantly influenced by orientation and placement. This study concludes that traditional mosque minarets offer a viable, sustainable option for passive cooling in hot climates.

Pararenal Aortic Thrombus in Patients Undergoing Aortic Aneurysm Repair With Chimney Technique.

INTRODUCTION: Chimney technique (chimney graft in abdominal aortic aneurysm repair [ChEVAR]) can be used to treat patients with pararenal aortic aneurysm unfit for open surgery and not suitable for custom-made fenestrated endograft. Since almost 1 in 5 patients undergo a reintervention within 3 years, features associated with higher risk of complications need to be investigated to tailor the follow-up schedule to each patient. The aim of our study was to assess the impact of mural thrombus in the pararenal aorta on perioperative and follow-up complications after ChEVAR. METHODS: All consecutive patients undergoing ChEVAR at our center from 2015 to 2022 were included in this retrospective study. Collected variables included number of target vessels, stent graft size, presence, and severity of mural thrombus in pararenal aorta, which was reported with a scoring system from 0 to 10 based on thrombus type, thickness area, and circumferenceAnalyzed outcomes included perioperative and follow-up complications. RESULTS: Thirty-one patients underwent ChEVAR during the study period. In 4 patients the indication for ChEVAR was type 1A endoleak after a previous endovascular aneurysm repair (EVAR). The number of target vessels was 1 in 17 patients (55%), 2 in 12 (39%), 3 in 1 (3%), and 4 in 1 (%). The mean mural thrombus score was 5.9. Complications were the following: type 1A endoleak in 4 cases (13%), chimney stent complications in 7 cases (23%) (including partial or total thrombosis, intrastent stenosis, displacement), renal function worsening during follow-up in 8 cases (26%). Overall survival was 90% at 2 years. Patients with severe mural thrombus showed lower freedom from ChEVAR-related complications (28% vs 59% at 2 years, p=0.023). CONCLUSIONS: The presence of severe pararenal aortic mural thrombus was associated with lower freedom from ChEVAR-related complications in patients undergoing ChEVAR for pararenal aortic aneurysm repair. Further research with a larger number of patients is required to confirm these results. CLINICAL IMPACT: The analysis of severity of mural thrombus in pararenal aorta, which was reported with a scoring system from 0 to 10 based on thrombus type, thickness area and circumference, can be useful and can be represent an important predictor element for complications in patient submitted to Chimney tecnique; in fact the presence of severe pararenal aortic mural thrombus was associated with lower freedom from ChEVAR-related complications in patients undergoing ChEVAR for pararenal aortic aneurysm repair. Then, in patient with pararenal aortic aneurysm, a preoperative evaluation could be focused on severity of mural thrombus to minimize the complications in ChEVAR tecnique or to change the surgical strategy.

Long-term outcomes of chimney endovascular aneurysm repair procedure for complex abdominal aortic pathologies.

OBJECTIVE: The aim of this study was to update our earlier experience and to evaluate long-term outcomes of chimney endovascular aortic repair performed for selected cases with complex abdominal aortic aneurysm. METHODS: A single-center retrospective cohort study was conducted on 51 consecutive patients who underwent chimney endovascular aortic repair procedure, deemed unfit for open surgical repair and fenestrated endovascular aneurysm repair, from October 2009 to November 2019. Kaplan-Meier analyses were used to assess the estimated overall survival, freedom from aneurysm related mortality, freedom from reintervention, freedom from target vessel instability, and freedom from type Ia endoleaks. RESULTS: Fifty-one patients (mean age, 77.1 ± 7.5 years) with a mean preoperative maximum aneurysm diameter of 74.2 ± 20.1 mm were included. Mean follow-up duration was 48.6 months (range, 0-136 months). Estimated overall survival at 5 and 7 years was 36.3% ± 7.1% and 18.3% ± 6.0%, respectively. Freedom from aneurysm-related mortality was 88.6% ± 4.9% at 7 years. Estimated freedom from type Ia endoleaks at 7 years was 91.8% ± 3.9%. A total of 21 late reinterventions were performed in 17 patients (33%). Most of them were performed to treat type II endoleaks with sac growth (47.6%; n = 10) and type Ib endoleak (23.8%; n = 5). Estimated freedom from reintervention at 7 years was 56.3% ± 7.9%. Estimated freedom from target vessel instability at 7 years was 91.5% ± 4.1%. CONCLUSIONS: The 7-year results of chimney endovascular aortic repair procedures performed in our center confirm the long-term safety and effectiveness of this technique in a series of high-risk patients with large aneurysms. The present study has, to the best of our knowledge, the longest follow-up for patients treated with chimney endovascular aortic repair, and it provides data to the scarce literature on the long-term outcomes of this procedure, showing acceptable to good long-term results.

Chimney Stenting vs BASILICA for Prevention of Acute Coronary Obstruction During Transcatheter Aortic Valve Replacement.

BACKGROUND: Coronary obstruction (CO) is a potentially life-threatening complication of transcatheter aortic valve replacement (TAVR). Chimney stenting or leaflet laceration with transcatheter electrosurgery (Bioprosthetic or Native Aortic Scallop Intentional Laceration to Prevent Iatrogenic Coronary Artery Obstruction [BASILICA]) are 2 techniques developed to prevent CO. OBJECTIVES: The aim of the present study was to compare periprocedural and 1-year outcomes of chimney and BASILICA in TAVR patients at high risk of CO. METHODS: This multicenter observational registry enrolled consecutive TAVR patients at high risk of CO, undergoing either preventive chimney stenting or BASILICA. Clinical success was defined as successful performance of the chimney or BASILICA technique without clinically relevant ostial CO. The primary endpoint was major adverse cardiovascular events, a composite of death, myocardial infarction, stroke, or unplanned target lesion coronary revascularization at 1 year. RESULTS: A total of 168 patients were included: 71 (42.3%) received chimney stenting, and 97 (57.7%) underwent BASILICA. Patients undergoing BASILICA had higher preprocedural risk of CO, as indicated by lower sinotubular junction height (18.2 ± 4.8 mm vs 14.8 ± 3.4 mm; P < 0.001) and diameter (28.2 ± 4.5 vs 26.8 ± 3.4; P = 0.029). Rates of periprocedural complications were similar between the 2 groups. Clinical success was 97.2% and 96.9% in chimney and BASILICA, respectively (P = 0.92). At 1-year follow-up, the cumulative incidence of major adverse cardiovascular events was 18.7% (95% CI: 11%-30.6%) in the chimney group and 19.9% (95% CI: 12.1%-31.5%) in the BASILICA group (log-rank P = 0.848), whereas chimney was associated with a numerically higher cardiovascular mortality than BASILICA (6.7% vs 1.3%; log-rank P = 0.168). CONCLUSIONS: Chimney stenting and BASILICA effectively prevent TAVR-induced acute CO. Both techniques seem to have comparable acceptable periprocedural and 1-year outcomes.

Cleaning Up the Chimney: Early Renal Stent Graft Thrombosis Following Endovascular Treatment of a Juxtarenal Aortic Aneurysm With the Chimney Technique.

The endovascular management of juxtarenal aortic aneurysms with the chimney technique (ch-EVAR) has gained popularity in recent years. It provides an alternative to open repair, allowing treatment of challenging anatomies with devices readily available in any vascular suite. The primary drawback persists as the occurrence of type-Ia endoleak from gutters and renal stent thrombosis. We present two cases of early renal stent graft thrombosis following chimney endovascular aneurysm repair. The first patient was an 80-year-old man who underwent single ch-EVAR and came back on the fifth post-op day with renal stent graft thrombosis. He was re-operated for recanalization and additional stenting of his chimney graft. The patient recovered well with no complications. The second case involved a 72-year-old man with a juxtarenal aneurysm, treated with ch-EVAR on both renal arteries. Unfortunately, on the 10th post-op day, he was referred to our department due to lumbar pain and acute renal failure due to chimney graft thrombosis bilaterally. The left renal chimney graft was recanalized by endovascular means. On the contrary, despite efforts of the endovascular and open approach, the right chimney graft and the right renal artery remained occluded. While ch-EVAR is a viable and off-the-shelf solution for urgent and complex juxtarenal aortic aneurysms, it should be performed with awareness of the potential for graft thrombosis and persistent endoleaks. Despite these complications, the chimney technique can still be a viable treatment option. A better understanding of the indications and advancements in the devices used can lead to better long-term results.