Mauricio S. Ribeiro

Prospective, nonrandomized study to evaluate endovascular repair of pararenal and thoracoabdominal aortic aneurysms using fenestrated-branched endografts based on supraceliac sealing zones

Purpose: To investigate outcomes of manufactured fenestrated and branched endovascular aortic repair (F‐BEVAR) endografts based on supraceliac sealing zones to treat pararenal aortic aneurysms and thoracoabdominal aortic aneurysms (TAAAs). Methods: A total of 127 patients (91 male; mean age, 75 ± 10 years old) were enrolled in a prospective, nonrandomized single‐center study using manufactured F‐BEVAR (November 2013‐March 2015). Stent design was based on supraceliac sealing zone in all patients with ≥ four vessels in 111 (89%). Follow‐up included clinical examination, laboratory studies, duplex ultrasound, and computed tomography imaging at discharge, 1 month, 6 months, and yearly. End points adjudicated by independent clinical event committee included mortality, major adverse events (any mortality, myocardial infarction, stroke, paraplegia, acute kidney injury, respiratory failure, bowel ischemia, blood loss >1 L), freedom from reintervention, and branch‐related instability (occlusion, stenosis, endoleak or disconnection requiring reintervention), target vessel patency, sac aneurysm enlargement, and aneurysm rupture. Results: There were 47 pararenal, 42 type IV, and 38 type I‐III TAAAs with mean diameter of 59 ± 17 mm. A total of 496 renal‐mesenteric arteries were incorporated by 352 fenestrations, 125 directional branches, and 19 celiac scallops, with a mean of 3.9 ± 0.5 vessels per patient. Technical success of target vessel incorporation was 99.6% (n = 493/496). There were no 30‐day or in‐hospital deaths, dialysis, ruptures or conversions to open surgical repair. Major adverse events occurred in 27 patients (21%). Paraplegia occurred in two patients (one type IV, one type II TAAAs). Follow‐up was >30 days in all patients, >6 months in 79, and >12 months in 34. No patients were lost to follow‐up. After a mean follow‐up of 9.2 ± 7 months, 23 patients (18%) had reinterventions (15 aortic, 8 nonaortic), 4 renal artery stents were occluded, five patients had type Ia or III endoleaks, and none had aneurysm sac enlargement. Primary and secondary target vessel patency was 96% ± 1% and 98% ± 0.7% at 1 year. Freedom from any branch instability and any reintervention was 93% ± 2% and 93% ± 2% at 1 year, respectively. Patient survival was 96% ± 2% at 1 year for the entire cohort. Conclusions: Endovascular repair of pararenal aortic aneurysms and TAAAs, using manufactured F‐BEVAR with supraceliac sealing zones, is safe and efficacious. Long‐term follow‐up is needed to assess the impact of four‐vessel designs on device‐related complications and progression of aortic disease.

Endovascular repair of thoracoabdominal aortic aneurysms using fenestrated and branched endografts

Purpose: The study purpose was to review the outcomes of patients treated for thoracoabdominal aortic aneurysms using endovascular repair with fenestrated and branched stent‐grafts in a single center. Methods: We reviewed the clinical data of the first 185 consecutive patients (134 male; mean age, 75 ± 7 years) treated for thoracoabdominal aortic aneurysms using fenestrated and branched stent‐grafts. Graft design evolved from physician‐modified endografts (2007‐2013) to off‐the‐shelf or patient‐specific manufactured devices in patients enrolled in a prospective physician‐sponsored investigational device exemption protocol (NCT 1937949 and 2089607). Outcomes were reported for extent IV and extent I to III thoracoabdominal aortic aneurysms, including 30‐day mortality, major adverse events, patient survival, primary target vessel patency, and reintervention. Results: A total of 112 patients (60%) were treated for extent IV thoracoabdominal aortic aneurysms, and 73 patients (40%) were treated for extent I to III thoracoabdominal aortic aneurysms. Demographics and cardiovascular risk factors were similar in both groups. A total of 687 renal‐mesenteric arteries (3.7 vessels/patient) were targeted by 540 fenestrations and 147 directional branches. Technical success was 94%. Thirty‐day mortality was 4.3%, including a mortality of 1.8% for extent IV and 8.2% for extent I to III thoracoabdominal aortic aneurysms (P = .03). Mortality decreased in the second half of clinical experience from 7.5% to 1.2%, including a decrease of 3.3% to 0% for extent IV thoracoabdominal aortic aneurysms (P = .12) and 15.6% to 2.4% for extent I to III thoracoabdominal aortic aneurysms (P = .04). Early major adverse events occurred in 36 patients (32%) with extent IV thoracoabdominal aortic aneurysms and 26 patients (36%) with extent I to III thoracoabdominal aortic aneurysms, including spinal cord injury in 2 patients (1.8%) and 4 patients (3.2%), respectively. Mean follow‐up was 21 ± 20 months. At 5 years, patient survival (56% and 59%, P = .37) and freedom from any reintervention (50% and 53%, P = .26) were similar in those with extent IV and extent I to III thoracoabdominal aortic aneurysms. Primary patency was 93% at 5 years. Conclusions: Endovascular repair of thoracoabdominal aortic aneurysms can be performed with high technical success and low mortality and morbidity. However, the need for secondary reinterventions and continued graft surveillance represents major limitations compared with results of conventional open surgical repair. Long‐term follow‐up is needed before the widespread use of these techniques in younger or lower‐risk patients.

Energy performance and greenhouse gas emissions of kelp cultivation for biogas and fertilizer recovery in Sweden

The cultivation of seaweed as a feedstock for third generation biofuels is gathering interest in Europe, however, many questions remain unanswered in practise, notably regarding scales of operation, energy returns on investment (EROI) and greenhouse gas (GHG) emissions, all of which are crucial to determine commercial viability. This study performed an energy and GHG emissions analysis, using EROI and GHG savings potential respectively, as indicators of commercial viability for two systems: the Swedish Seafarm projects seaweed cultivation (0.5ha), biogas and fertilizer biorefinery, and an estimation of the same system scaled up and adjusted to a cultivation of 10ha. Based on a conservative estimate of biogas yield, neither the 0.5ha case nor the up-scaled 10ha estimates met the (commercial viability) target EROI of 3, nor the European Union Renewable Energy Directive GHG savings target of 60% for biofuels, however the potential for commercial viability was substantially improved by scaling up operations: GHG emissions and energy demand, per unit of biogas, was almost halved by scaling operations up by a factor of twenty, thereby approaching the EROI and GHG savings targets set, under beneficial biogas production conditions. Further analysis identified processes whose optimisations would have a large impact on energy use and emissions (such as anaerobic digestion) as well as others embodying potential for further economies of scale (such as harvesting), both of which would be of interest for future developments of kelp to biogas and fertilizer biorefineries.

A simple and fast procedure for in situ determination of water in ethanol fuel

A simple and inexpensive procedure, based on the high difference in solubility of sodium chloride in ethanol and water, is proposed to estimate the water content in ethanol fuel. The ionic concentration of solutions saturated with the salt is monitored by conductometric measurements with a linear response up to 16% water in an alcoholic medium and a limit of detection of 0.05% (v/v). The procedure is precise (coefficient of variation of 0.6%, n = 10) and accurate (results in agreement with those obtained by Karl Fischer amperometric titration at the 95% confidence level). An indicating electronic device exploiting the same principle was proposed for in situ monitoring of ethanol fuel samples aiming at the fast detection of unconformities. The device can be operated by nonexperts, generating a binary response indicated by coloured LEDs, and it successfully classified commercial samples spiked with different amounts of water.

Characterization of the Kallikrein-kinin System, Metalloproteinases, and Their Tissue Inhibitors in the In-stent Restenosis after Peripheral Percutaneous Angioplasty

BACKGROUND The kallikrein-kinin system (KKS) has several direct and indirect effects on cells and cellular mediators involved in the inflammatory process. Studies about inflammation on percutaneous transluminal angioplasty with stent (PTA/stent) to treat peripheral arterial disease (PAD) in humans are scarce. The matrix metalloproteinases (MMPs) are calcium-dependent zinc-containing endopeptidases expressed in various cells and tissues such as fibroblasts, inflammatory cells, and, smooth muscle cells. Changes in the extracellular matrix (ECM) take place in the pathogenesis of many cardiovascular pathologies. MMPs and their inhibitors (tissue inhibitors of metalloproteinases [TIMPs]) are crucial in ECM remodeling in both physiologic and pathologic conditions. The aim of this study was to evaluate the role of the KKS and the MMP metabolism, which are important mediators that may contribute to tissue repair, in the process of arterial restenosis due to intimal hyperplasia in the femoropopliteal segment with the aim of developing new interventions. METHODS Thirty-nine consecutive patients were selected (regardless of ethnic group, age, or sex) for revascularization, who underwent PTA/stent of the femoropopliteal segment. Twenty-five patients with the same clinical characteristics who were scheduled for diagnostic angiography but not subjected to PTA/nitinol stent were also selected. The concentrations in blood of total and kininogen fractions were evaluated using immunoenzymatic methods. Plasma kallikrein was evaluated by the colorimetric method. Tissue kallikrein was evaluated by the spectrophotometric method. The activity of kininase II was measured by fluorometric analysis. Quantification of MMPs was performed by zymography, which is an electrophoresis technique, and TIMPs were measured by enzyme-linked immunosorbent assay. RESULTS Among the 31 patients who completed the survey, there were 10 cases of angiographically defined restenosis of >50%, and 21 cases without restenosis. There was an increase in the concentrations of the substrates (high-molecular-weight kininogens and lower molecular weight kininogens) and enzymes (plasma and tissue kallikrein) in patients with restenosis, indicating activation of this inflammatory pathway in these patients. The activity of kininase II was not significantly different between the groups of patients studied. There were no statistical differences between restenosis and no restenosis patients for both MMPs and TIMPs dosage, but there is an upward trend of MMPs in time 6 months in patients with restenosis. CONCLUSIONS With the aim of identifying factors contributing to restenosis after endovascular intervention, this study showed evidence of high activation of the KKS in the pathologic inflammatory process of PTA/stent restenosis. In the other hand, it could not show participation of metalloproteinase metabolism in PTA/stent restenosis.

Endovascular Approach to Transplant Renal Artery Stenosis.

BACKGROUND The endovascular approach has shown high initial technical success rates, good patency rates, and minimal complications in treating transplant renal artery stenosis (TRAS). The objective of this study was to describe our experience with an endovascular approach to TRAS. MATERIAL AND METHODS We performed a retrospective single-institutional review of all kidney transplant procedures performed at our institution from September 2009 to September 2014. All consecutive cases of TRAS were included. RESULTS From a total of 183 kidney transplantations, 16 patients had TRAS. Mean time from transplantation to TRAS diagnosis was 201.8 days. Stenoses or hemodynamic significant kinkings were located at the anastomosis (7), proximal (5) and middle (4) portions of the transplant artery. All patients were treated with angioplasty and primary balloon-expanding stenting. Early technical success was 93.75% and local complication rate was 12.5%. No deaths occurred. Mean serum creatinine level dropped from 3.87 mg/dL to 2.91 mg/dL after 24 hours; 1.85 mg/dL after one month; and 1.67 mg/dL after three months (P<0.05). Mean estimated glomerular filtration rate increased from 31.60 mL/min to 39.53 mL/min after 24 hours; 50.92 mL/min after one month; and 55.05 mL/min after three months (P<0.05). Doppler ultrasound criteria normalized after the procedure. Number of classes of antihypertensive drugs was not different before and after the procedure (P=0.38). Mean follow-up time was 9.75 months. One patient had a restenosis and required surgical intervention to restore graft function. CONCLUSIONS The endovascular approach to TRAS with primary balloon-expanding stenting was safe and had a high rate of technical success. It was effective for restore and maintain the renal function in transplant kidney grafts with a low rate of restenosis.

Assessment of aortic wall thrombus predicts outcomes of endovascular repair of complex aortic aneurysms using fenestrated and branched endografts

Objective The goal of this study was to investigate the correlation between atherothrombotic aortic wall thrombus (AWT) and clinical outcomes in patients treated by fenestrated‐branched endovascular aortic repair (F‐BEVAR) and present a new classification system for assessment of AWT burden. Methods The clinical data of 301 patients treated for pararenal and thoracoabdominal aortic aneurysms (TAAAs) by F‐BEVAR was reviewed. The study excluded 89 patients with extent I to III TAAA because of extensive laminated thrombus within the aneurysm sac. Computed tomography angiograms were analyzed in all patients to determine the location, extent, and severity of atherothrombotic AWT. The aorta was divided into three segments: ascending and arch (A), thoracic (B) and renal‐mesenteric (C). Volumetric measurements (cm3) of AWT were performed using TeraRecon software (TeraRecon Inc, Foster City, Calif). These volumes were used to create an AWT index by dividing the AWT volume from the total aortic volume. A classification system was proposed using objective assessment of the number of affected segments, thrombus type, thickness, area, and circumference. Clinical outcomes included 30‐day mortality, neurologic and gastrointestinal complications, renal events (Risk, Injury, Failure, Loss of kidney function, End‐stage renal disease [RIFLE]), and solid organ infarction. Results The study included 212 patients, 169 men (80%) and 43 women (20%), with a mean age of 76 ± 7 years. A total of 700 renal‐mesenteric arteries were incorporated (3.1 ± 1 vessels/patient). AWT was classified as mild in 98 patients (46%) and was considered moderate or severe in 114 (54%). There was one death (0.5%) at 30 days. Solid organ infarction was present in 50 patients (24%), and acute kidney injury occurred in 45 patients (21%) by RIFLE criteria. An association with higher AWT indices was found for time to resume enteral diet (P = .0004) and decline in renal function (P = .0003). Patients with acute kidney injury 2 by RIFLE criterion had significantly higher (P = .002) AWT index scores in segment B. Spinal cord injury occurred in three patients (1.4%) and stroke in four (1.9%), but were not associated with the AWT index. Severity of AWT using the new proposed classification system correlated with the AWT index in all three segments (P < .001). Any of the end points occurred in 35% of the patients with mild and in 53% of those with moderate or severe AWT (P = .016). Conclusions AWT predicts solid organ infarction, renal function deterioration, and longer time to resume enteral diet after F‐BEVAR of pararenal and type IV TAAAs. Evaluation of AWT should be part of preoperative planning and decision making for selection of the ideal method of treatment in these patients.

Elastase‐2, an angiotensin II‐generating enzyme, contributes to increased angiotensin II in resistance arteries of mice with myocardial infarction

Angiotensin II (Ang II), whose generation largely depends on angiotensin‐converting enzyme (ACE) activity, mediates most of the renin‐angiotensin‐system (RAS) effects. Elastase‐2 (ELA‐2), a chymotrypsin‐serine protease elastase family member 2A, alternatively generates Ang II in rat arteries. Myocardial infarction (MI) leads to intense RAS activation, but mechanisms involved in Ang II‐generation in resistance arteries are unknown. We hypothesized that ELA‐2 contributes to vascular Ang II generation and cardiac damage in mice subjected to MI.

MicroRNAs and Current Concepts on the Pathogenesis of Abdominal Aortic Aneurysm

Objective: Abdominal aortic aneurysm is an important cause of morbidity and mortality in the elderly. Currently, the only way to prevent rupture and death related to abdominal aortic aneurysms is through surgical intervention. Endovascular treatment is associated with less morbidity than conventional treatment. The formation of an aneurysm is a complex multifactorial process, involving destructive remodeling of the connective tissue around the affected segment of the aorta wall. MicroRNAs are small sequences of non-coding RNAs that control diverse cellular functions by promoting degradation or inhibition of translation of specific mRNAs. A profile aberrant expression of miRNAs has been linked to human diseases, including cardiovascular dysfunction.

Cirurgia aberta e endovascular no tratamento de aneurisma de artéria poplítea: experiência de cinco anos do HCRP-FMRP-USP

Background popliteal artery aneurysms (PAAs) account for 70% of peripheral aneurysms. Surgery is indicated for aneurysms that have diameters greater than 2.0 cm or are symptomatic. Repair can be achieved by conventional surgical techniques or using endovascular methods, which are becoming increasingly popular, but for which there is not yet a consensus on indications. Objective To describe the experience of treating PAAs at the vascular and endovascular surgery department of the Hospital das Clinicas de Ribeirao Preto, affiliated to the Universidade de Sao Paulo (Brazil). Method A review was conducted of cases of conventional and endovascular repair of PAAs over the last 5 years, analyzing demographic data, comorbidities, surgical indications, preoperative and early and late postoperative complications, length of hospital stay and patency, during follow-up of up to 1 year. Results During the period analyzed, ten endovascular surgeries (ES) and 21 open surgeries (OS) were performed. The ES group exhibited a higher frequency of comorbidities. There was a higher frequency of symptomatic patients in the OS group (85%) than in the ES group (40%). The ES group exhibited a lower number of clinical and surgical complications. There were no statistical differences between the groups in terms of age or length of hospital stay. Primary patency at 1 year was 80% in the ES group and 75% in the OS group. Conclusions Endovascular treatment for PAAs offers good results in terms of patency, with acceptable complication rates, in patients with high surgical risk and favorable anatomy. Controlled studies are therefore warranted to validate the endovascular technique and afford it the status of an alternative procedure for use in selected cases.