Central extracorporeal membrane oxygenation as a bridge to recovery in patients with myocardial stunning after coronary artery bypass grafting

Background: The role of central extracorporeal membrane oxygenation (ECMO) post coronary artery bypass grafting (CABG) in older patients is debatable. The objectives of our study were to investigate the role of central veno-arterial (V-A) ECMO as a bridge to recovery in patients with myocardial stunning after CABG and its effect on mortality in this group of patients. Methods: Seventy-five patients had central ECMO as a bridge to recovery  after CABG because of myocardial stunning; 45 of them (60%) had survived (group 1), and mortality occurred in 30 patients (40%) (group 2). Preoperative risk factors such as hypertension, stroke, and renal failure were comparable between groups. In non-survivors, left main disease was more common (19 (63.3%) vs. 13 (28.9%); p= 0.003) and SYNTAX score was higher (Median 33 (25th- 75th percentiles); 33 (29- 35) vs. 26 (25- 32); p< 0.001). Results: Cross-clamp time was shorter in group 1 (58 minutes; (52-62) vs 115.5 minutes; (84- 161) in group 2; p< 0.001). Cardiopulmonary bypass time was shorter in group 1 compared to group 2 (83; (70-90) vs. 155.5; (60 -120) minutes; p< 0.001). ECMO duration was longer in group 2 (6 days; (6-7) vs. 3 days; (3-4); p<0.001). Stroke occurred in 10 patients (33.33%) in group 2 vs. 1 patient (2.22%) in groups 1; p< 0.001. Longer cross-clamp (OR: 1.61, 95% CI: 1.11- 2.31, p= 0.011) and bypass time (OR: 1.76; 95% CI: 1.57- 1.99; p= 0.048) predicted postoperative mortality. Conclusion: Central ven-arterial extramembrane oxygenation can be used as a bridge to recovery in patients with stunned myocardium post coronary bypass grafting, especially in centers where heart transplantation and ventricular assist devices are not available

Hypothermic circulatory arrest with or without antegrade cerebral perfusion for aortic arch surgery in infants

Background: Antegrade cerebral perfusion (ACP) minimizes deep hypothermic circulatory arrest (DHCA) duration during arch surgery in infants, which may impact the outcomes of the repair. We aimed to evaluate the effect of adding antegrade cerebral perfusion to deep hypothermic circulatory arrest on DHCA duration and operative outcomes of different aortic arch operations in infants. Methods: We retrospectively collected data from infants (<20 weeks old) who underwent aortic arch reconstruction (Norwood operation, arch reconstruction for the hypoplastic arch and interrupted aortic arch) using DHCA alone (n=88) or combined with ACP (n=26). We excluded patients who had concomitant procedures and those with preoperative neurological disability. Results: There was no difference between groups as regards the age, gender, and the operation performed (p= 0.64; 0.87 and 0.50; respectively). Among the 114 patients, 11 (9.6%) had operative mortality, and 14 (12.3%) had cerebral infarction diagnosed with CT scanning. Adding ACP to DHCA significantly reduced DHCA duration from 50.7 ± 10.6 minutes to 22.4 ± 6.2 minutes (p<0.001) and lowered the mortality (11 vs. 0; p=0.066) and cerebral infarction (13 vs. 1; p=0.18). No statistically significant difference between the two groups in terms of ischemic time (p=0.63) or hospital stay duration (p=0.47). Conclusion: Using ACP appears to reduce the DHCA duration and was associated with better survival and neurological outcomes of aortic arch surgery in infants. A study with longer follow-up to evaluate the long-term neurological sequelae is recommended

Comparison of automated fastener (Cor-Knot) versus manually tied knots in patients undergoing minimally invasive mitral valve replacement

Introduction: Automated knot fastener has been used in minimally invasive valve surgery to alleviate the longer total operating time and improve outcomes. Their advantages over manual knot tying remain questionable. This study aims to compare automated knot fasteners' efficacy with conventional knot-pushers in minimally invasive mitral valve replacements (MiMVR). Methods: Between 2016 and 2020, 50 patients underwent isolated mechanical mitral valve replacement via right mini-thoracotomy in rheumatic or degenerative mitral valve disease. The patients were grouped into two groups. Group I (n= 25) included patients who had MiMVR using the Cor-knot device, and Group II (n= 25) had MiMVR using the conventional knot-pusher. Primary endpoints were cross-clamp, cardiopulmonary bypass, and total operative times and the secondary outcomes were paravalvular leak and reoperation. There were no significant differences in the demographic data between the two groups. Results: Cross-clamp time (79± 1.11 vs. 98.88± 1.34 min; P<0.001), cardiopulmonary bypass time ( 132 (Q1- Q2: 129- 134) vs. 148 (140- 155) min; P<0.001) and operative times ( 206 (203- 209) vs. 228 (223- 234) min; P<0.001) were significantly shorter in Group I. There was no difference in postoperative complications between groups. The early paravalvular leak occurred in one patient (4%) in Group I and required valve re-exploration. In Group II, four patients (16%) had a paravalvular leak; 3 of them were severe and required valve re-exploration (P= 0.35). Transthoracic echocardiography at discharge revealed no evidence of a paravalvular leak in both groups. Conclusion: Automated fastener device (Cor-knot) could reduce operative times during minimally invasive mitral valve replacement. Operative complications are comparable between both techniques, and follow-up studies are recommended

Sutureless Perceval versus Bioprosthetic Aortic Valve, Single Center Experience

Background: High-risk patients are currently presenting for aortic valve replacement (AVR). Sutureless valves may decrease the operative risk in those patients. The objective of this study was to compare the short-term and one-year follow-up results of the sutureless Perceval valve versus bioprosthetic aortic valve. Methods: The data of patients who underwent elective AVR with bioprosthesis were collected From March 2012 to March 2017. The patients were divided into two groups; group 1 included the patients who had a sutureless aortic valve (Perceval) (n= 25; 3.57% of total AVR patients), and group 2 included patients who had conventional bioprosthesis (n= 50; 7.1% of total AVR patients). Results: The median age of patients in group 1 was 67 years (25th- 75th percentiles; 64-71), and in group 2 was 66 years  (25th- 75th percentiles: 63 to 69). There is no significant difference in the patients’ comorbidities between the two groups. The median duration of the ischemic time was significantly lower in group 1 (33 (25th- 75th percentiles: 32- 35)  vs. 60.5 (58- 66), respectively; p< 0.001). Perceval valve was used more commonly in patients who had minimally invasive AVR (n= 21 (84%) in group 1 vs. 11 (22%) in group 2; p<0.001). Postoperative complications were comparable between both groups. The early paravalvular leak was non-significantly higher in group 1 (12% vs. 2%; p= 0105). The mean postoperative gradient was lower in group 1 (7 (7-9) vs. 10 (8-12) mmHg; p<0.001). The changes in valvular gradient were not significantly different between both groups (p= 0.5). The hospital stay was lower in patients received Perceval valve (Coefficient: -1.3; 95% Cl: -2.3- -0.29; p=0.012)  Conclusion:  Sutureless aortic valve (Perceval) is a new surgical technique for AVR, with potential advantages of reducing cross-clamp time and a subsequent reduction in myocardial ischemia, duration of cardiopulmonary bypass, and maintaining satisfactory hemodynamic outcomes through reducing patient prosthesis mismatch. All these advantages could help in decreasing postoperative hospital stay.&nbsp

The performance of the supra-annular Top-Hat aortic valves compared to the standard Carbomedics valves

Background: The CarboMedics Top-Hat aortic valve prosthesis was designed to be implanted in a supra-annular position. This study aimed to compare the hemodynamic performance of the Top-Hat aortic prostheses versus the standard CarboMedics aortic valve prostheses. Methods: The study included 98 patients who had aortic valve replacement and were divided into two groups. Group A included 60 patients who had standard aortic valve prostheses, and Group B included 38 patients who had the Top-Hat aortic prostheses. The study endpoints were hospital outcomes, the effective orifice area, and the pressure gradient during a one-year follow-up. Results: There was no significant difference in the baseline echocardiographic data and risk factors between the groups. The patients who had Top-Hat aortic prosthesis were younger, with a mean age of 47.5 (44-55) years, and those who had the standard prosthesis were 53.5 (48-56) years old (P= 0.02). The cardiopulmonary bypass time was significantly less in the Top-Hat prosthesis group with an average of 78 min (75- 81) compared to 88 min (84- 95) in the other group (P ˂0.001). The effective orifice surface area was significantly larger in the group with Top-Hat prosthesis; 0.9 mm/m2 (0.88- 0.92) compared to 0.84 mm/m 2 (0.79- 0.87) for the standard aortic valve prosthesis group (P ˂0.001). The pressure gradient over the aortic valve decreased significantly postoperatively (coefficient -1.98 (-2.21- -1.75); P˂0.001). Patients with Top-Hat valves had significantly lower gradient (coefficient: -4.22 (-6.61- -1.82); P= 0.001), while age had no effect on the pressure gradient (coefficient: 0.1 ( -0.07- 0.27); P= 0.25). Conclusion: The Top-Hat CarboMedics prostheses could be superior to the standard CarboMedics aortic valve prosthesis regarding the effective orifice area and pressure gradient over the valve

Mitral valve repair for myxomatous mitral regurgitation; Respect or Resect

Background: The superiority of mitral repair using resection of the posterior leaflet versus neo-artificial chordea is still debatable. The objective of this study was to compare leaflet resection versus chordal replacement for mitral valve repair in patients with isolated myxomatous degeneration of the posterior mitral valve leaflet.   Methods: This study was conducted on 199 patients with severe symptomatic mitral regurgitation due to myxomatous mitral valve degeneration. Patients were grouped into two groups: Group (1): Respect technique which included  76 patients who had limited resection of the anterior leaflet, chordal transfer, and replacement of anterior leaflet chordae by polytetrafluoroethylene sutures, and placement of annuloplasty ring. Group (2): Resect technique included  123 patients where the operation was done by resecting the prolapsed mid scallop of the posterior leaflet and placement of flexible annuloplasty ring. Results: There was no difference between both groups regarding gender. Patients in the Respect group were younger (37 (25th- 75th percentiles: 29- 44) vs. 54 (48- 60) years, P<0.001). The minimally invasive approach was more commonly used in patients who had resection techniques (20 (26.32%) vs. 106 (86.18%); P<0.001). Ischemic (99 (95- 106) vs. 79 (75- 82); P<0.001) and cardiopulmonary bypass times (134.5 (130- 138.5) vs. 99 (97- 104) min; P<0.001) were higher in the Respect group. Blood loss was more in the Resect group (370 (305- 390) vs. 550 (490- 600) ml; P<0.001). There were no differences in the postoperative complications between groups. ICU stay was longer in patients in the Resect group (5 (5- 6) vs. 7 (6- 8) days; P<0.001). Mitral valve gradient after 12 months was significantly higher in the Resect group (3 (3- 3.5) vs. 4 (3- 5) mmHg; P<0.001). Mitral valve reoperation was required more in patients in the Respect group (5 (6.58%) vs. 1 (0.81%); P= 0.03). Conclusions: Both Respect and resect techniques for mitral valve repair had comparable outcomes and durability. The repair technique should be tailored according to the mitral valve pathology

Timing of repair of ischemic ventricular septal rupture; results of early vs. late repair

Background: The optimal time to repair ischemic ventricular septal rupture (VSR) is debatable. We compared the outcomes, including operative mortality, between patients who underwent early vs. late VSR repair. Methods: Twenty-eight patients presented with VSR were included in this study. Patients were grouped according to the timing of repair into two groups; the early repair group (n= 12) and the late repair group (n= 16). The primary endpoint was operative mortality. Results: There was no difference in age, gender, and associated comorbidities between between early and late repair. Anteroapical VSR was the most common type in both groups. There was no difference in the number of bypass grafts in both groups. Ischemic (95 (88- 142.5) vs. 137 (120- 147.5) min; P= 0.028) and cardiopulmonary bypass times (123.5 (115.5- 177.5) vs. 172.5 (152.5- 185) min; P= 0.023) were significantly shorter in patients who had delayed repair. Nine patients (75%) had operative mortality in the early repair group versus three patients (18.75%) in the late repair group (P= 0.006). There were no differences in blood loss, stroke, wound infection, ICU, and ward stay among the surviving patients. Conclusion: Delayed repair of ischemic ventricular septal rupture could be associated with lower mortality in properly selected patients. Additionally, the delayed repair could decrease the ischemic and cardiopulmonary bypass times

The Impact of Stealthy Attacks on Smart Grid Performance: Tradeoffs and Implications

The smart grid is envisioned to significantly enhance the efficiency of energy consumption, by utilizing two-way communication channels between consumers and operators. For example, operators can opportunistically leverage the delay tolerance of energy demands in order to balance the energy load over time, and hence, reduce the total operational cost. This opportunity, however, comes with security threats, as the grid becomes more vulnerable to cyber-attacks. In this paper, we study the impact of such malicious cyber-attacks on the energy efficiency of the grid in a simplified setup. More precisely, we consider a simple model where the energy demands of the smart grid consumers are intercepted and altered by an active attacker before they arrive at the operator, who is equipped with limited intrusion detection capabilities. We formulate the resulting optimization problems faced by the operator and the attacker and propose several scheduling and attack strategies for both parties. Interestingly, our results show that, as opposed to facilitating cost reduction in the smart grid, increasing the delay tolerance of the energy demands potentially allows the attacker to force increased costs on the system. This highlights the need for carefully constructed and robust intrusion detection mechanisms at the operator.Comment: Technical report - this work was accepted to IEEE Transactions on Control of Network Systems, 2016. arXiv admin note: substantial text overlap with arXiv:1209.176

EFFECT OF DIFFERENT LEVELS OF NPK AND MICRONUTRIENT ON YIELD AND DISTRIBUTION OF NUTRIENTS IN MAIZE UNDER IRRIGATED AGRICULTURE

A field experiment was carried out in Kafer El Kadera village at El–Monofia Governorate, during 5 consecutive years, 2010–2014, to test the effects of NPK and balanced fertilization on the yield and its components, and distribution of nutrients in different parts of maize (var.30K8).There was a significant increase of the number of leaves/plant, the length of cob, the number of rows in the cob and the number of grains in the row as a result of treated plants with NPK according to soil testing plus foliar application of micronutrients by 34.18, 27.94, 32.182, and 33.43%, respectively.There was also a significant increase in the chilling % rate, weight of 100 grains and yield of grain / plant, yield /ton/ha by 16.52, 35.39, 68.40, and 72.92%, respectively.There was an increase in the concentration of nitrogen in the grains, Envelope and leaves and increase in the concentration of phosphorus in the Envelope (husk leaves), Cob core and leaves, Also, increase in the concentration of potassium in the Envelope, stem and root, and increase in calcium concentration in grains and leaves also, increase in sodium in the envelope and roots.Values of iron and manganese concentrations were increased in grains, envelope and leaves, as well as increased concentration of zinc and copper in leaves.Significant positive correlation was found between concentrations of most leaf nutrients concentrations and nutrient concentrations of grain except significant negative correlation between P concentrations in leaves and K concentrations in grains and between Mg in leaves and Zn in grains and between Na in leaves and Fe concentrations in grains. As well as significant positive correlation were found between Ca, Zn and yield

Electrodeposition of Cu on Arbitrary Substrates for CVD Graphene Synthesis

Graphene, a 2-dimentional carbon material, exhibits optical, mechanical, chemical and electrical properties, making it a viable option for a wide range of industrial applications. Despite graphene’s potential, challenges in the cost and energy efficiency of the synthetic process as well as quality of synthesized graphene still stand. Amongst the most popular and industrially practical methods used to synthesize graphene, is the employment of Chemical Vapor Deposition (CVD) to grow graphene on a copper substrate/catalyst. Here we explore methods to reduce cost while maintaining high quality graphene synthesis by optimizing the recyclability of copper substrate.Ope