A Concept for a Leaky Wave Antenna Oscillator With Second Order Degeneracy

We exploit a second order exceptional point of degeneracy (EPD) to enhance frequency purity and oscillation stability in oscillators. The EPD we consider in this paper is a regular band edge (RBE) that exists in lossless and gainless periodic waveguides. We present an example of single-ladder oscillator that may act as a leaky wave antenna (LWA). The oscillator we develop has 8 unit-cells that form a resonant cavity and an active element is used to compensate for the losses and start the oscillation. We show that the oscillation frequency is in proximity of the RBE frequency thanks to the second order degeneracy

Distributed Degenerate Band Edge Oscillator

We propose a new class of oscillators by engineering the dispersion of two-coupled periodic waveguides to exhibit a degenerate band edge (DBE). The DBE is an exceptional point of degeneracy (EPD) of order four, i.e., representing the coalescence of four eigenmodes of a waveguide system without loss and gain. We present a distributed DBE oscillator realized in periodic coupled transmission lines with a unique mode selection scheme that leads to a stable single-frequency oscillation, even in the presence of load variation. The DBE oscillator potentially leads to a boost of the efficiency and performance of RF sources, thanks to the unique features associated to the EPD concept. This class of oscillators is promising for improving discrete-distributed coherent sources and can be extended to radiating structures to achieve a new class of active integrated antenna arrays

Laparoscopy in management of appendicitis in high-, middle-, and low-income countries: a multicenter, prospective, cohort study.

BACKGROUND: Appendicitis is the most common abdominal surgical emergency worldwide. Differences between high- and low-income settings in the availability of laparoscopic appendectomy, alternative management choices, and outcomes are poorly described. The aim was to identify variation in surgical management and outcomes of appendicitis within low-, middle-, and high-Human Development Index (HDI) countries worldwide. METHODS: This is a multicenter, international prospective cohort study. Consecutive sampling of patients undergoing emergency appendectomy over 6 months was conducted. Follow-up lasted 30 days. RESULTS: 4546 patients from 52 countries underwent appendectomy (2499 high-, 1540 middle-, and 507 low-HDI groups). Surgical site infection (SSI) rates were higher in low-HDI (OR 2.57, 95% CI 1.33-4.99, p = 0.005) but not middle-HDI countries (OR 1.38, 95% CI 0.76-2.52, p = 0.291), compared with high-HDI countries after adjustment. A laparoscopic approach was common in high-HDI countries (1693/2499, 67.7%), but infrequent in low-HDI (41/507, 8.1%) and middle-HDI (132/1540, 8.6%) groups. After accounting for case-mix, laparoscopy was still associated with fewer overall complications (OR 0.55, 95% CI 0.42-0.71, p < 0.001) and SSIs (OR 0.22, 95% CI 0.14-0.33, p < 0.001). In propensity-score matched groups within low-/middle-HDI countries, laparoscopy was still associated with fewer overall complications (OR 0.23 95% CI 0.11-0.44) and SSI (OR 0.21 95% CI 0.09-0.45). CONCLUSION: A laparoscopic approach is associated with better outcomes and availability appears to differ by country HDI. Despite the profound clinical, operational, and financial barriers to its widespread introduction, laparoscopy could significantly improve outcomes for patients in low-resource environments. TRIAL REGISTRATION: NCT02179112

Comparative study of laparoscopic ventral mesh rectopexy versus perineal stapler resection for external full-thickness rectal prolapse in elderly patients: enhanced outcomes and reduced recurrence rates—a retrospective cohort study

Background: In elderly patients with external full-thickness rectal prolapse (EFTRP), the exact differences in postoperative recurrence and functional outcomes between laparoscopic ventral mesh rectopexy (LVMR) and perineal stapler resection (PSR) have not yet been investigated. Methods: We conducted a retrospective multicenter study on 330 elderly patients divided into LVMR group (n = 250) and PSR (n = 80) from April 2012 to April 2019. Patients were evaluated before and after surgery by Wexner incontinence scale, Altomare constipation scale, and patient satisfaction questionnaire. The primary outcomes were incidence and risk factors for EFTRP recurrence. Secondary outcomes were postoperative incontinence, constipation, and patient satisfaction. Results: LVMR was associated with fewer postoperative complications (p &lt; 0.001), lower prolapse recurrence (p &lt; 0.001), lower Wexner incontinence score (p = 0.03), and lower Altomare’s score (p = 0.047). Furthermore, LVMR demonstrated a significantly higher surgery–recurrence interval (p &lt; 0.001), incontinence improvement (p = 0.019), and patient satisfaction (p &lt; 0.001) than PSR. Three and 13 patients developed new symptoms in LVMR and PSR, respectively. The predictors for prolapse recurrence were LVMR (associated with 93% risk reduction of recurrence, OR 0.067, 95% CI 0.03–0.347, p = 0.001), symptom duration (prolonged duration was associated with an increased risk of recurrence, OR 1.131, 95% CI 1.036–1.236, p = 0.006), and length of prolapse (increased length was associated with a high recurrence risk (OR = 1.407, 95% CI = 1.197–1.655, p &lt; 0.001). Conclusions: LVMR is safe for EFTRP treatment in elderly patients with low recurrence, and improved postoperative functional outcomes

Intraoperative endomanometric laparoscopic Nissen fundoplication improves postoperative outcomes in large sliding hiatus hernia with severe gastroesophageal reflux disease. A retrospective cohort study

Background: Laparoscopic Nissen Fundoplication (LNF) is the gold standard surgical intervention for gastroesophageal reflux disease (GERD). LNF can be followed by recurrent symptoms or complications affecting patient satisfaction. The aim of this study is to assess the value of the intraoperative endomanometric evaluation of esophagogastric competence and pressure combined with LNF in patients with large sliding hiatus hernia (&gt; 5&nbsp;cm) with severe GERD (DeMeester score &gt;100). Materials and methods: This is a retrospective, multicenter cohort study. Baseline characteristics, postoperative dysphagia and gas bloat syndrome, recurrent symptoms, and satisfaction were collected from a prospectively maintained database. Outcomes analyzed included recurrent reflux symptoms, postoperative side effects, and satisfaction with surgery. Results: 360 patients were stratified into endomanometric LNF (180 patients, LNF+) and LNF alone (180 patients, LNF). Recurrent heartburn (3.9% vs. 8.3%) and recurrent regurgitation (2.2% vs. 5%) showed a lower incidence in the LNF+ group (P=0.012). Postoperative score III recurrent heartburn and score III regurgitations occurred in 0% vs. 3.3% and 0% vs. 2.8% cases in the LNF+ and LNF groups, respectively (P=0.005). Postoperative persistent dysphagia and gas bloat syndrome occurred in 1.75% vs. 5.6% and 0% vs. 3.9% of patients (P=0.001). Score III postoperative persistent dysphagia was 0% vs. 2.8% in the two groups (P=0.007). There was no redo surgery for dysphagia after LNF+. Patient satisfaction at the end of the study was 93.3% vs. 86.7% in both cohorts, respectively (P=0.05). Conclusions: Intraoperative high-resolution manometry (HRM) and endoscopic were feasible in all patients, and the outcomes were favorable from an effectiveness and safety standpoint

Biliary fistula and late recurrence of liver hydatid cyst: Role of cysto-biliary communication: A prospective multicenter study

Background: Hydatid cyst disease (HCD) is common in certain locations. Surgery is associated with postoperative biliary fistula (POBF) and recurrence. The primary aim of this study was to identify whether occult cysto-biliary communication (CBC) can predict recurrent HCD. The secondary aim was to assess the role of cystic fluid bilirubin and alkaline phosphatase (ALP) levels in predicting POBF and recurrent HCD. Aim: To identify whether occult CBC can predict recurrent HCD. The secondary aim was to assess the role of cystic fluid bilirubin and ALP levels in predicting POBF and recurrent HCD. Methods: From September 2010 to September 2016, a prospective multicenter study was undertaken involving 244 patients with solitary primary superficial stage cystic echinococcosis 2 and cystic echinococcosis 3b HCD who underwent laparoscopic partial cystectomy with omentoplasty. Univariable logistic regression analysis assessed independent factors determining biliary complications and recurrence. Results: There was a highly statistically significant association (P ≤ 0.001) between cystic fluid biochemical indices and the development of biliary complications (of 16 patients with POBF, 15 patients had high cyst fluid bilirubin and ALP levels), where patients with high bilirubin-ALP levels were 3405 times more likely to have biliary complications. There was a highly statistically significant association (P ≤ 0.001) between biliary complications, biochemical indices, and the occurrence of recurrent HCD (of 30 patients with recurrent HCD, 15 patients had high cyst fluid bilirubin and ALP; all 16 patients who had POBF later developed recurrent HCD), where patients who developed biliary complications and high bilirubin-ALP were 244.6 and 214 times more likely to have recurrent hydatid cysts, respectively. Conclusion: Occult CBC can predict recurrent HCD. Elevated cyst fluid bilirubin and ALP levels predicted POBF and recurrent HCD

Safety and Efficacy of Myval Implantation in Patients with Severe Bicuspid Aortic Valve Stenosis-A Multicenter Real-World Experience.

Bicuspid aortic valve (BAV) is the most common valvular congenital anomaly and is apparent in nearly 50% of candidates for AV replacement. While transcatheter aortic valve implantation (TAVI) is a recommended treatment for patients with symptomatic severe aortic stenosis (AS) at all surgical risk levels, experience with TAVI in severe bicuspid AS is limited. TAVI in BAV is still a challenge due to its association with multiple and complex anatomical considerations. A retrospective study has been conducted to investigate TAVI's procedural and 30-day outcomes using the Myval transcatheter heart valve (THV) (Meril Life Sciences Pvt. Ltd. Vapi, Gujarat, India) in patients with severe bicuspid AS. Data were collected on 68 patients with severe bicuspid AS who underwent TAVI with the Myval THV. Baseline characteristics, procedural, 30-day echocardiographic and clinical outcomes were collected. The mean age and STS PROM score were 72.6 ± 9.4 and 3.54 ± 2.1. Procedures were performed via the transfemoral route in 98.5%. Major vascular complications (1.5%) and life-threatening bleeding (1.5%) occurred infrequently. No patient had coronary obstruction, second valve implantation or conversion to surgery. On 30-day echocardiography, the mean transvalvular gradient and effective orifice area were 9.8 ± 4.5 mmHg and 1.8 ± 0.4 cm2, respectively. None/trace aortic regurgitation occurred in 76.5%, mild AR in 20.5% and moderate AR in 3%. The permanent pacemaker implantation rate was 8.5% and 30-day all-cause death occurred in 3.0% of cases. TAVI with the Myval THV in selected BAV anatomy is associated with favorable short-term hemodynamic and clinical outcomes

One-Year Outcomes after Myval Implantation in Patients with Bicuspid Aortic Valve Stenosis-A Multicentre Real-World Experience

Background: Bicuspid aortic valve (BAV) affects approximately 1.5% of the general population and is seen in nearly 50% of candidates for aortic valve replacement (AVR). Despite increasingly utilised transcatheter aortic valve implantation (TAVI) in aortic stenosis (AS) patients, its use among patients with severe bicuspid AS is limited as BAV is a heterogeneous disease associated with multiple and complex anatomical challenges. Aim: To investigate the one-year outcomes of TAVI using the balloon-expandable Myval transcatheter heart valve (THV) (Meril Life Sciences Pvt. Ltd., Vapi, India) in patients with severe bicuspid AS. Methods and results: We collected data from consecutive patients with bicuspid AS who underwent TAVI with the Myval THV and had at least one-year follow-up. Baseline characteristics, procedural, and 30-day echocardiographic and clinical outcomes were collected. Sixty-two patients were included in the study. The median age was 72 [66.3, 77.0] years, 45 (72.6%) were males, and the mean STS PROM score was 3.2 &plusmn; 2.2%. All TAVI procedures were performed via the transfemoral route. The median follow-up duration was 13.5 [12.2, 18.3] months; all-cause mortality was reported in 7 (11.3%) patients and cardiovascular hospitalisation in 6 (10.6%) patients. All-stroke was reported in 2 (3.2%), permanent pacemaker implantation 5 (8.3%), and myocardial infarction 1 (1.6%) patients. The echocardiographic assessment revealed a mean pressure gradient of 10 [8, 16.5] mmHg, effective orifice area 1.7 [1.4, 1.9] cm2, moderate AR in 1 (2%), mild AR in 14 (27%), and none/trace AR in 37 (71%). In total, 1 patient was diagnosed with valve thrombosis (2.1%), Stage II (moderate) haemodynamic deterioration was seen in 3 (6.4%), and stage III (severe) haemodynamic deterioration in 1 (2.1%) patient. Conclusions: TAVI with the Myval THV in selected BAV anatomy is associated with favourable one-year hemodynamic and clinical outcomes

Global economic burden of unmet surgical need for appendicitis

Background: There is a substantial gap in provision of adequate surgical care in many low-and middle-income countries. This study aimed to identify the economic burden of unmet surgical need for the common condition of appendicitis. Methods: Data on the incidence of appendicitis from 170 countries and two different approaches were used to estimate numbers of patients who do not receive surgery: as a fixed proportion of the total unmet surgical need per country (approach 1); and based on country income status (approach 2). Indirect costs with current levels of access and local quality, and those if quality were at the standards of high-income countries, were estimated. A human capital approach was applied, focusing on the economic burden resulting from premature death and absenteeism. Results: Excess mortality was 4185 per 100 000 cases of appendicitis using approach 1 and 3448 per 100 000 using approach 2. The economic burden of continuing current levels of access and local quality was US $92 492 million using approach 1 and$73 141 million using approach 2. The economic burden of not providing surgical care to the standards of high-income countries was $95 004 million using approach 1 and$75 666 million using approach 2. The largest share of these costs resulted from premature death (97.7 per cent) and lack of access (97.0 per cent) in contrast to lack of quality. Conclusion: For a comparatively non-complex emergency condition such as appendicitis, increasing access to care should be prioritized. Although improving quality of care should not be neglected, increasing provision of care at current standards could reduce societal costs substantially

Pooled analysis of who surgical safety checklist use and mortality after emergency laparotomy

Background: The World Health Organization (WHO) Surgical Safety Checklist has fostered safe practice for 10 years, yet its place in emergency surgery has not been assessed on a global scale. The aim of this study was to evaluate reported checklist use in emergency settings and examine the relationship with perioperative mortality in patients who had emergency laparotomy. Methods: In two multinational cohort studies, adults undergoing emergency laparotomy were compared with those having elective gastrointestinal surgery. Relationships between reported checklist use and mortality were determined using multivariable logistic regression and bootstrapped simulation. Results: Of 12 296 patients included from 76 countries, 4843 underwent emergency laparotomy. After adjusting for patient and disease factors, checklist use before emergency laparotomy was more common in countries with a high Human Development Index (HDI) (2455 of 2741, 89⋅6 per cent) compared with that in countries with a middle (753 of 1242, 60⋅6 per cent; odds ratio (OR) 0⋅17, 95 per cent c.i. 0⋅14 to 0⋅21, P &lt; 0⋅001) or low (363 of 860, 42⋅2 percent; OR 0⋅08, 0⋅07 to 0⋅10, P &lt; 0⋅001) HDI. Checklist use was less common in elective surgery than for emergency laparotomy in high-HDI countries (risk difference −9⋅4 (95 per cent c.i. −11⋅9 to −6⋅9) per cent; P &lt; 0⋅001), but the relationship was reversed in low-HDI countries (+12⋅1 (+7⋅0 to +17⋅3) per cent; P &lt; 0⋅001). In multivariable models, checklist use was associated with a lower 30-day perioperative mortality (OR 0⋅60, 0⋅50 to 0⋅73; P &lt; 0⋅001). The greatest absolute benefit was seen for emergency surgery in low-and middle-HDI countries. Conclusion: Checklist use in emergency laparotomy was associated with a significantly lower perioperative mortality rate. Checklist use in low-HDI countries was half that in high-HDI countries