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.

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).

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.

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.

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.

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.

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.

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.

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.

High risk of coronary artery obstruction during TAVR, how to avoid it?

BACKGROUND: Coronary artery obstruction after percutaneous aortic replacement is a complication with high short-term mortality secondary to the lack of timely treatment. There are various predictors of coronary obstruction prior to valve placement such as the distance from the ostia, the degree of calcification, the distance from the sinuses; In such a situation some measures must be taken to prevent and treat coronary obstruction. CASE PRESENTATION: An 84-year-old male, with severe aortic stenosis and high surgical risk, who was treated with TAVR. However, during the deployment of the valve he presented hemodynamic instability secondary to LMCA obstruction. The intravascular image showed obstruction of the ostium secondary to the displacement of calcium that he was successfully treated with a chimney stent technique. CONCLUSIONS: The high degree of calcification and the left ostium near the annulus are conditions for obstruction of the ostium at the time of valve release; In this context, provisional stenting prior to TAVR in patients at high risk of obstruction should be considered as a safe prevention strategy to achieve the success of the procedure.

Configuration of the neoaortic root after chimney reconstruction in the Norwood procedure.

OBJECTIVES: After staged reconstruction for hypoplastic left heart syndrome, the neoaortic root tends to dilate, and the incidence of significant neoaortic valve insufficiency increases with time. This study aimed to evaluate the mid-term outcomes of the neoaortic root geometries and valve function after chimney reconstruction in the Norwood procedure. METHODS: Between 2013 and 2021, 20 consecutive patients who underwent chimney reconstruction during the Norwood procedure for hypoplastic left heart syndrome and its variants in our institution were enrolled. The actual diameters of the following points were measured, and Z-scores were calculated based on the normal aortic root geometries using the long axis view of echocardiography at the pre-Norwood stage and the lateral view of angiography at pre-Glenn, pre-Fontan, post-Fontan and follow-up (age 5-6 years) stages: neoaortic valve annulus; sinus of Valsalva; sinotubular junction; and ascending aorta just proximal to the anastomosis to the aortic arch. The degree of neoaortic valve regurgitation was evaluated by echocardiography at each stage. RESULTS: The median follow-up period was 3.9 years. Neoaortic roots after chimney reconstruction were spared from progressive dilation over time. With growth, the conical configuration of the neoaortic roots was preserved without geometrical distortion. The Z-scores of the annulus, sinus of Valsalva, sinotubular junction and ascending aorta ranged roughly from 4 to 6, 4 to 6, 2 to 4 and 0 to 2, respectively. All neoaortic valves at each stage had mild or no regurgitation. CONCLUSIONS: Chimney reconstruction prevented neoaortic root dilation and avoided significant neoaortic valve regurgitation in the mid-term. These neoaortic dimensions with smooth flow profiles in the neoaorta after chimney reconstruction may have contributed to the current results. Further studies are needed to clarify the long-term outcomes.

Pioneering Piezoelectric-Driven Atomic Hydrogen for Efficient Dehalogenation of Halogenated Organic Pollutants.

The electrocatalytic hydrodehalogenation (EHDH) process mediated by atomic hydrogen (H*) is recognized as an efficient method for degrading halogenated organic pollutants (HOPs). However, a significant challenge is the excessive energy consumption resulting from the recombination of H* to H2 production in the EHDH process. In this study, a promising strategy was proposed to generate piezo-induced atomic H*, without external energy input or chemical consumption, for the degradation and dehalogenation of HOPs. Specifically, sub-5 nm Ni nanoparticles were subtly dotted on an N-doped carbon layer coating on BaTiO3 cube, and the resulted hybrid nanocomposite (Ni-NC@BTO) can effectively break C-X (X = Cl and F) bonds under ultrasonic vibration or mechanical stirring, demonstrating high piezoelectric driven dehalogenation efficiencies toward various HOPs. Mechanistic studies revealed that the dotted Ni nanoparticles can efficiently capture H* to form Ni-H* (Habs) and drive the dehalogenation process to lower the toxicity of intermediates. COMSOL simulations confirmed a "chimney effect" on the interface of Ni nanoparticle, which facilitated the accumulation of H+ and enhanced electron transfer for H* formation by improving the surface charge of the piezocatalyst and strengthening the interfacial electric field. Our work introduces an environmentally friendly dehalogenation method for HOPs using the piezoelectric process independent of the external energy input and chemical consumption.

Systematic Review and Meta-analysis of Fenestrated and Chimney/Snorkel Techniques for Endovascular Repair of Juxtarenal Aortic Aneurysms.

OBJECTIVES: Comparative effectiveness of fenestrated endovascular aneurysm repair (FEVAR) and chimney graft endovascular aneurysm repair (ChEVAR) for juxtarenal aortic aneurysms (JAAs) remains unclear. Our objective was to identify and analyze the current body of evidence comparing the effectiveness of both techniques for JAA. METHODS: We performed a systematic review and meta-analysis comparing the effectiveness of FEVAR and ChEVAR for JAA repair. We searched MEDLINE, EMBASE, and Cochrane Register for Controlled Trials from January 1, 1990, for randomized and non-randomized studies assessing outcomes of FEVAR and ChEVAR for JAA repair. Screening, data extraction, risk of bias assessment, and GRADE (Grading of Recommendations, Assessments, Development, and Evaluations) certainty of evidence were performed in duplicate. Data were pooled statistically where possible. RESULTS: Nine retrospective cohort studies comparing the use of FEVAR and ChEVAR for juxtarenal aneurysm were included for meta-analysis. The FEVAR and ChEVAR arms of the meta-analysis consisted of 726 participants and 518 participants, respectively. There were 598 (86.8%) and 332 (81.6%) men in each arm. The mean diameter was larger in the ChEVAR arm (59 mm vs 52.5 mm). Both techniques had similar rates of postoperative 30-day mortality, 3.38% (8/237) versus 3.52% (8/227), acute kidney injury, 16.76% (31/185) versus 17.31% (18/104), and major adverse cardiac events, 7.30% (46/630) versus 6.60% (22/333). The meta-analysis supported the use of FEVAR for most outcomes, with significant advantage for technical success (odds ratio [OR]: 3.24, 95% CI: 1.24-8.42) and avoidance of type 1 endoleak (OR: 5.76, 95% CI: 1.94-17.08), but a disadvantage for spinal cord ischemia (OR: 10.21, 95% CI: 1.21-86.11), which had a very low number of events. The quality of evidence was "moderate" for most outcomes. CONCLUSION: Both endovascular techniques had good safety profiles. The evidence does not support superiority of either FEVAR or ChEVAR for JAA. CLINICAL IMPACT: While lack of equipoise has hampered the design of randomised trials of open versus endovascular repair of juxtarenal aortic aneurysms, concern about the durability of endovascular repair highlights the need for stronger evidence of the comparative efficacy of endovascular techniques. This review performed meta-analysis and evidence appraisal of recent data from large observational studies comparing fenestrated and chimney techniques, using a comprehensive outcome set. Superiority of either intervention could not be established due to differences in participants' baseline risk in each study arm. However, data suggests that both techniques are safe and suitable for use when indicated.

Extensive thoracoabdominal aortic aneurysm as initial presentation in Takayasu arteritis: case series and literature review.

Background: Aortic aneurysm as a presenting feature in Takayasu's arteritis is very rare. Here, we report three cases of extensive thoracoabdominal aortic aneurysm in Takayasu's arteritis as initial presentation. Case summary: All three cases were males and presented with complaints of abdominal pain and refractory hypertension. The diagnosis was made from the finding of thickened and calcified aortic wall, stenosis of visceral arteries, and age < 40 years at diagnosis. Case 1 was a 34 years male with aortic aneurysm extending from left subclavian artery to infrarenal aorta. He underwent endovascular repair of aneurysm by sandwich chimney technique in view of impending aneurysm rupture. Case 2, a 37 years male had aortic aneurysm from descending thoracic aorta (D4 vertebral body) to infrarenal aorta (L4 level). While being evaluated for repair, he had sudden death probably due to ruptured aneurysm. Case three, a 40 years male had aortic aneurysm extending from left subclavian artery to aortic bifurcation and stenosis of visceral arteries. He did not consent for repair and died one year later due to chronic kidney disease and related complications. Discussion: Thoracoabdominal aortic aneurysm is a very rare manifestation in Takayasu's arteritis; more common in males. Endovascular repair is challenging but feasible. Long-term monitoring and repeat intervention may be needed due to young age of patients and disease progression.

Early and Mid-Term Outcomes of Using the Chimney Technique in Redo Mitral Valve Replacement in Patients with a Small Mitral Annulus.

The outcomes of redo mitral valve replacement (Re-MVR) in a small mitral annulus with the use of the chimney technique are not well documented. The purpose of this study is to present our early experience with this group of patients, illustrating the periop-erative complications and mortality outcomes. From 2019 to 2020, 77 consecutive patients underwent Re-MVR with the use of the chimney technique because of a small mitral annulus. To evaluate heart structural integrity and clinical outcomes, postoperative clinical data and echocardiograms were examined. The mean age was 56.7 ± 15.98 years. All patients underwent mitral valve surgery, of which 62 were mitral valve replacements, 7 mitral valve repairs, and 8 double valve replacements. The preoperative mitral valve mean gradient was 18.07 ± 9.40 mmHg, and the postoperative mitral prosthesis size was 28.51 ± 1.22 mm. The median increment of mitral size enlargement was 4 (0, 6) valve sizes. The mean mitral gradient coming out of the operating room was 10.34 ± 2.12 mmHg, and at the follow-up echocardiogram performed at 3 years after the procedure, it was 10.36 ± 1.70 mmHg. One-year survival was 93.3%, while the 4-year survival rate was 89.3%, with no reoperation. The use of the chimney technique in small mitral valve re-mitral valve replacement results in larger valve sizes. Moreover, the mean gradients over the mitral valve are acceptable both intraoperatively and over time.