Numerical Simulation and Experiment of Hydraulic Loss of Two-Stage Flap Valves

As a type of flap valve evolved from integral flap valve, two-stage flap valve has the advantages of large opening angle, small hydraulic loss and small impact force on the flap valve seat when the flap valve is closed. In order to analyze and study the hydraulic loss characteristics of the two-stage flap valve, this paper takes a pump station as an example. Based on theoretical analysis, combined with numerical simulation and model test, the hydraulic loss of two-stage flap valve is studied, and the relationship between hydraulic loss and pump station flow is obtained. According to the test results, the hydraulic loss of two-stage flap valve increases with the increase of flow rate under the same opening angle of flap valve. Under the same flow condition, the larger the opening angle of the flap valve is, the smaller the hydraulic loss of the two-stage flap valve is. When the opening angle of the upper flap valve is greater than 46° and the opening angle of the lower flap valve is greater than 64°, the hydraulic loss is less than 70mm and tends to be stable. The influence of hydraulic loss on the performance of pump device is gradually weakened. The relationship between hydraulic loss and flow of two-stage flap valve no longer satisfies the relationship of square under the constant opening angle. Moreover, the larger the opening angle of the two-stage flap valve is, the greater the relationship between hydraulic loss and flow is. Compared with the integral flap valve, the two-stage flap valve has better structural form and hydraulic characteristics, and has little influence on the performance of the pump device, which can provide reference for the application of the two-stage flap valve in the pump station.

Correlation between gastroesophageal flap valve abnormality and novel parameters in patients with gastroesophageal reflux disease symptoms by the lyon consensus

Gastroesophageal flap valve (GEFV) grading is a simple and reproducible parameter. There is limited information about the association between GEFV abnormality and novel parameters in patients with gastroesophageal reflux disease(GERD) symptoms by the Lyon Consensus. To investigate the value of GEFV grading in GERD, the clinical data of 320 patients with GERD symptoms who underwent endoscopy, 24-h multichannel intraluminal impedance-pH (MII-pH) monitoring, and high-resolution manometry (HRM) were retrospectively analyzed. The percentage of acid exposure time (AET%)(4.2 [1.5–7.4] vs. 1.3 [0.3–4.2], P < 0.001) and the proportion of abnormal esophagogastric junction (EGJ) morphology (71 [87.7%] vs. 172 [72.0%], P = 0.011) were significantly higher, while the mean nocturnal baseline impedance (MNBI) (2068.3 [1658.4–2432.4] vs. 2228.5 [1794.8–2705.3]Ω, P = 0.012) and post-reflux swallow-induced peristaltic wave index (PSPWI) (19.7 [13.9–29.0] vs. 33.3 [25.0–44.0]%, P < 0.001) were significantly lower in the abnormal GEFV group compared with the normal GEFV group. AET% and EGJ morphology showed positive correlations with GEFV grade, while PSPWI and MNBI showed negative correlations. Patients with an abnormal GEFV had a significantly greater risk of conclusive evidence of GERD compared to those with a normal GEFV (OR 3.035, 95% CI 1.758–5.240, P < 0.001). Further, when identifying patients with conclusive evidence of GERD, abnormal GEFV had a specificity of 80.4% (95% CI 75.3–85.5%). GEFV grading might be regarded as supportive evidence for GERD diagnosis.

Trans-Oral Incisionless Fundoplication (TIF): How I Do It and Why

Transoral Incisionless Fundoplication (TIF) is designed to create a 3 cm length, 270° to 300°, omega-shaped flap valve, reconstructing the structure and function of the lower esophageal sphincter (LES), including the gastric sling fibers. As such, TIF is a treatment option for GERD patients with an intact crura, but have lost the integrity and function of the LES. In patients requiring a hernia repair, TIF can be used concomitantly (cTIF). While there are a number of steps to the TIF 2.0 procedure, many of the sequences are repetitive and follow a standardized protocol, optimizing efficiency, safety, and scalability.

Abstract 15801: Early and Late Risk of Mortality or Development of Severe Pulmonary Hypertension Following Closure of Ventricular Septal Defects in Children With Severe Pulmonary Hypertension and Elevated Pulmonary Vascular Resistance Using Traditional or Uni-directional Flap Valve Patch Closure

Introduction: Children with large ventricular septal defects, severe pulmonary hypertension (PHT), and elevated pulmonary vascular resistance (PVR) are frequently denied operation in low and middle-income countries secondary to concerns of high mortality and development of severe pulmonary hypertension following operation, early and late. Hypothesis: We hypothesized that closure with a uni-directional flap valve patch (DP) would provide lower mortality and better survival without severe PHT. Methods: From 5/96 - 12/2016 all patients undergoing VSD closure with severe PHT and elevated PVR by either traditional (TP) or DP closure were followed annually. Baseline and O 2 provocation catheterization were performed before operation. Echocardiograms were performed at discharge and follow-up. The decision on TP or DP closure was based upon age and surgeon preference. Beginning in 2005 all patients regardless of technique received sildenafil 3 mgs/kg/day for 3 months before operation. Results: The number of patients receiving operation was 129, of which 40 received the DP. Males were 66/129, age and weight differed significantly for DP group compared to the TP group (7.5 vs 2.6 years, p<0.001 and 20 vs 11.5 kgs, p<0.001).Catheterization baseline data, PVR 9.0 vs 7.4 for DP and TP respectively (p<0.001), negative vasoactive test 32.5% vs 13.5% for DP and TP respectively (p=0.016). Mortality was 1/40 for DP and 9/89 for TP. Pulmonary to Systemic systolic pressure ratio was lower at discharge vs baseline cath (0.38 vs 0.99, p<0.001). Predictors of late severe pulmonary hypertension were PVR/SVR >0.5, p<0.024; and a negative vasoactive test of <10% decrease, p<0.001. PHT at last follow-up, none or mild 86/115 (74.8%), moderate 16/115 (13.9%) or severe 13/115 (11.3%). Conclusions: DP patients had less risk of death and both groups had few patients with severe PHT at late follow-up..