Modified Bernoulli Equation Research Articles

Correlation of Transthoracic Echocardiographic Estimates of Right Ventricular Pressure with Right Ventricular Pressure Measurements on Cardiac Catheterization in Children with Pulmonary Hypertension

ObjectivesEvaluate correlation of non-invasive echocardiographic estimates of right ventricular systolic pressure with measurements on cardiac catheterization in children with pulmonary hypertension DesignRetrospective chart review SettingQuaternary academic children's hospital ParticipantsPatients < 18yrs with a diagnosis of pulmonary hypertension and confirmatory cardiac catheterization from 2015-2018. Measurements and main resultsWe analyzed the correlation between measures of right ventricular systolic pressure using nonparametric Spearman rho (ρ) with statistical significance set at p<0.05. Results111 children with biventricular circulation, strictly defined pulmonary hypertension, and adequate tricuspid regurgitation on echocardiogram to estimate right ventricular systolic pressure using the modified Bernoulli equation. Median age and weight were 4.3 years and 14.4 kg. Median right ventricular systolic pressure estimated by tricuspid regurgitant velocity on echocardiography was 55 mmHg (IQR 45-75 mmHg) plus right atrial pressure. On cardiac catheterization, median right ventricular systolic pressure was 57 mmHg (IQR 46-75 mmHg). Echocardiographic estimates of right ventricular systolic pressure were moderately well correlated with right ventricular systolic pressure directly measured on catheterization (ρ=0.44, 95% CI 0.27-0.6, p<0.001) with a median difference of 4mmHg (IQR -10-17). Subgroup analysis revealed that echocardiography and catheterization measurements correlated well in children with suprasystemic right ventricular pressure on cardiac catheterization (ρ=0.75, 95% CI 0.51-0.99, p<0.001) although catheterization measurements were a median of 26 mmHg (IQR 12-31) higher than echocardiographic estimates in this subgroup. ConclusionsIn children with pulmonary hypertension, echocardiographic estimates of right ventricular pressure correlated moderately well with gold standard measurements by cardiac catheterization with stronger correlation in children with suprasystemic right ventricular pressures. This is reassuring for clinicians who must rely on echocardiography for risk stratification prior to anesthetizing children with pulmonary hypertension.

On the flow past ellipses in a Hele-Shaw cell

In this work we investigate the effect of vertical confinement and inertia on the flow past thin ellipses in a Hele-Shaw cell (with centre line velocity $U_c$ and height 2 $h$ ) with different aspect ratios for symmetrical flows and at an angle of attack, using asymptotic methods and numerical simulations. A Stokes region is identified at the ellipse vertices which results in flow different to flow past bluff bodies. Comparison with asymptotic analysis indicates close agreement over the ‘flat’ portion of the ellipse, for $\delta =(b/a)=0.05$ , where $a$ and $b$ are the semi-major and -minor ellipse axes, respectively. Two flow conditions are investigated for ellipses at an angle of attack of 10 $^\circ$ for a fixed $\delta =0.05$ . Firstly, for $\varLambda =(U_ca/\nu )(h/a)^2 \ll 1$ , the effect of increasing the vertical confinement of the Hele-Shaw cell results in the rear stagnation point (RSP) moving from close to the potential-flow prediction when $\epsilon =h/a$ is very small to the two-dimensional Stokes-flow prediction when $\epsilon$ is large. Secondly, for a fixed $\epsilon \ll 1$ , when inertia is increased past $\varLambda ={O}(\epsilon )$ the RSP moves towards the trailing edge and is located there for $\varLambda ={O}(1)$ . Under these conditions an attached exponentially decaying shear layer or ‘viscous tail’ is formed. A modified Bernoulli equation of the depth-averaged flow, together with the Kutta–Joukowski theorem is used to predict the drag and lift coefficients on the ellipse, which include a linear and a nonlinear contribution, corresponding to a Hele-Shaw and circulation component, respectively. Close agreement is found up to $\varLambda ={O}(1)$ .

Thermodynamic Concepts in Civil Engineering

Thermodynamics is not always done well or usefully brought to bear in civil engineering. This paper addresses historical aspects of misunderstandings of thermodynamic concepts; applies the Second Law of Thermodynamics to applications including shock waves in compressible fluid flow, the tidal bore, spillway flow , and junction flow. Additional applications of thermodynamics in civil engineering are discussed. These include deriving hydraulic transient wave celerities for waterhammer analyses; the First Law of Thermodynamics for a closed system and for a control volume; one-dimensional flow, energy loss due to friction; parallel incompressible flow; application of the control volume to a pressure conduit; the modified Bernoulli equation; tees with small inflow and outflow branches; isentropic flow of a perfect gas and its application to flow metering, determination of choked flow conditions, and determination of the shaft power required to drive a blower.

Confirmation of the First Law of Thermodynamics in Theory and Extended Bernoulli Equation

The internal energy change of ideal gas does not depend on the volume and pressure. The internal energy change of real gas has not any relation with the volume and pressure, which had been proved. If the internal energy change had not any relation with the volume and pressure, we could confirm the first law of thermodynamics in theory. Simultaneously, the internal energy change is the state function that shall be able to be proved in theory. If the internal energy change depended on the volume and pressure, we could not prove that the internal energy change is the state function and the chemical thermodynamics theory is right. The extended or modified Bernoulli equation can be derived from the energy conservation law, and the internal energy change, heat, and friction are all considered in the derivation procedure. The extended Bernoulli equation could be applied to the flying aircraft and mechanical motion on the gravitational field, for instance, the rocket and airplane and so on. This paper also revises some wrong ideas, viewpoints, or concepts about the thermodynamics theory and Bernoulli equation.

Luminal pressure gradient and risk of arteriovenous fistula nonmaturation.

While arteriovenous fistula (AVF) nonmaturation is a major issue of hemodialysis care, an effective treatment to improve AVF maturation remains lacking. AVF introduces pulsatile arterial blood flow into its venous limb and produces high luminal pressure gradient, which may have adverse effect on vascular remodeling. As such, the aim of the present study is to investigate effect of luminal pressure gradient on AVF nonmaturation. This single-center, prospective observational study includes patients receiving autologous AVF creation. Participants received early postoperative ultrasound 5–7 days after surgery to collect parameters including diameters, flow rates, and volume at inflow and outflow sites. Luminal pressure gradient was estimated by using modified Bernoulli equation. The outcome was spontaneous AVF maturation within 8 weeks after surgery without intervention. Thirty patients were included, of which the mean age was 66.9 years and 70% were male. At the end of study, 13 (43.3%) patients had spontaneous AVF maturation. All demographic and laboratory characteristics were similar between patients with mature and nonmature AVF. Regarding ultrasonographic parameters, nonmature AVF showed significantly higher inflow/outflow diameter ratio, inflow velocity, and luminal pressure gradient. While these 3 parameters were significantly correlated, multivariate logistic regression showed their significant association with AVF nonmaturation. Receiver operating characteristic curve exhibited their high predictive value for AVF nonmaturation. Our findings showed that higher inflow/outflow ratio, inflow velocity, and AVF luminal pressure gradient in early postoperative ultrasound predicted risk of AVF nonmaturation. Reducing inflow/outflow diameter ratio or inflow rate may be an approach to improve AVF maturation. The predictive value of this early assessment might have impact on the clinical practice of AVF care.

Measurement of low Reynolds number flow emanating from a Turing pattern microchannel array using a modified Bernoulli equation technique

An experimental investigation of the air flow emanating from a Turing pattern microchannel array into an open atmosphere at very low Reynolds (Re) numbers is presented. As designed, the microchannel structure has channel sizes ranging between 0.6 mm and 1.5 mm with a depth of 0.6 mm. The development of a modified Bernoulli equation analysis method to determine fluid flow speed is introduced. Specifically, a low cost, large (11.11 mm inner diameter) flexible tube probe was employed to measure the fluid total pressure field distribution at a fixed distance from the outlets of the microchannel array. Using subsequent numerical modeling of the outlet-to-tube fluid flow interactions, a flow speed dependent correction factor for the determined dynamic pressure field is proposed. The experimentally measured fluid flow distribution is consistent with the expected flow field pattern obtained by additional computational modeling of flow through and exiting the entire Turing pattern microchannel manifold structure. The pressure measurement and post-processing technique for determining flow velocity may be adapted to a wide range of low-speed (e.g., Re≤100) fluid flow measurement scenarios.

Determination of the Microinjected Cytosolic Concentration by Using Mathematical Models of Fluid Dynamics.

The precise determination of the intracellular concentration of a drug is a major challenge in drug discovery. Microinjection is a very effective technique for the introduction of macromolecules into single cells. However, due to the large number of parameters that need to be adjusted and the complex physical mechanisms involved, there are currently no means by which the concentration of a microinjected intracellular compound could be theoretically estimated. In this paper, we present a method for the theoretical estimation of intracellular drug concentration, based on the framework of classical fluid mechanism theory - specifically, the modified Bernoulli equation. We introduce into Bernoulli's classical equation the effect of friction due to the non-laminar regimes of the injected fluid. We also study the compatibility of our theoretical estimation model with variations in injection time and concentration of the compound inside the microinjection needle. Finally, microinjected calcium concentrations estimated with the theoretical model were compared with those determined experimentally in several cell types, by using a Fura-2-based Ca2+ imaging technique.

Abstract 12217: Accurate Prediction of Systolic Peak-to-Peak Gradient in Children With Pulmonary Valve Stenosis

Objective: To evaluate the correlation between transthoracic echocardiography (TTE) derived gradients and invasive RV-PA peak-to-peak systolic gradient (iPG) and the predictability of these values in children with pulmonary valve stenosis (PVS). Introduction: Historically, correlations have been found between the Doppler-derived peak echo gradient (ePG), using the modified Bernoulli equation and invasive hemodynamic indices. This has led to the ePG being a widely used estimate of the degree of stenosis and an indicator of timing to consider intervention in children with PVS. However, large disparities observed between these invasive and non-invasive measurements have called into question the reliability of ePG to screen patients for consideration of pulmonary valvoplasty. Methods: We performed a retrospective chart review of 119 children who underwent pulmonary valvoplasty between January 2010 and January 2020 and selected 51 patients who had "simple" PVS in whom a TTE was performed within 6 months prior to the procedure. We evaluated the correlation between TTE parameters [Maximum velocity (Vmax), Mean Gradient (MG), ePG], and iPG. We then used the mathematical functions resulting from the correlation models to predict iPG. Results: All the assessed models were statistically significant and presented a strong correlation. When the differences between echocardiographic parameters and iPG were evaluated, ePG demonstrated the least accuracy in predicting iPG, erroneously estimating the real value by &gt;10mm Hg in 66% of cases. The MG presented a more accurate estimation of iPG, showing a narrower range of variance, with an error of &gt;10mm Hg in less than 30% of cases. We then modeled several mathematical functions of Vmax, MG, and ePG to predict iPG, and found that a derived function of Vmax ( f iPG) distributed by BSA (fiPG =12.7[Vmax]-17.3[BSA]) produced the most accurate results. Conclusions: There is a strong correlation between pre-procedural TTE parameters and iPG, but when ePG is used to estimate iPG, up to two-thirds of cases could be inappropriately characterized. We found that MG was a better predictor and that a mathematical function derived from Vmax and BSA ( f iPG) was the most accurate predictor of iPG.

Aortic stenosis reexpanded – a novel approach to determine aortic valve area with phase contrast cardiovascular magnetic resonance imaging

Abstract Background Transthoracic echocardiography (TTE) has become the diagnostic standard for evaluating aortic stenosis (AS) severity, mainly because of its advantages in comparison to the gold standard of cardiac catheterization. However, its inaccuracies in determining stroke volume (SV) and consequentially computing aortic valve area (AVA) call for a more precise and dependable method. Phase contrast cardiovascular magnetic resonance imaging (PC-CMR) is an aspiring tool to push these boundaries. Purpose The aim of this study was to validate a novel and simple approach based on PC-CMR against the invasive and echocardiographic determination of SV and AVA in patients with moderate and severe AS. Methods A total of 50 patients with moderate or severe AS underwent TTE, cardiac catheterization and CMR; AVA by PC-CMR was determined via plotting momentary flow across the valve against momentary flow velocity. SV via CMR was measured directly via PC-CMR and volumetrically using cine images. Invasive SV and AVA were determined via Fick principle and Gorlin formula, respectively. TTE yielded SV and AVA using the continuity equation. Finally, gradients were calculated via the modified Bernoulli equation. Results SV by PC-CMR showed a strong correlation with cine-CMR with no significant bias (r: 0.730, p&amp;lt;0.001; SV by PC-CMR: 85±31ml; SV by cine-CMR: 85±19ml, p=0.829). Peak gradients determined by PC-CMR were 65±29mmHg and correlated inversely with AVA by PC-CMR (r: −0.371; p=0.008). Mean AVA during the whole systolic phase showed a moderate correlation (r: 0.544, p&amp;lt;0.001) to invasive AVA with a small bias (AVA by CMR: 0.78±0.25cm2 versus invasive AVA: 0.70±0.23cm2, bias: 0.08cm2, p=0.017). Inter-methodical correlation and bias of AVA as measured by TTE and invasive AVA (AVA by TTE: 0.81±0.23cm2, r: 0.580, p&amp;lt;0.001, bias 0.11cm2, p&amp;lt;0.001) were similar to AVA by PC-CMR and invasive AVA. Conclusion PC-CMR provides a great option to yield reliable and solid SV values in patients with moderate and severe AS. Furthermore, continuous determination of flow volumes and flow velocities is able to determine AVA in these patients in an easy and reproducible manner. Our novel approach shines a light on the diagnostic potential of PC-CMR for non-invasive AS grading, especially in cases where echocardiography reaches its limits and where clinical findings appear inconclusive. Funding Acknowledgement Type of funding sources: None. Central IllustrationCine (l,r) and PC-CMR (m) images in AS

Pulmonary Hypertension in Sickle Cell Disease: The Role of Activated Blood Coagulation and Inflammation.

Introduction: Pulmonary hypertension (PHT) is a common complication of sickle cell disease (SCD). The pathogenesis of PHT in this setting is likely multifactorial. There is an abundance of evidence to suggest that the coagulation system is activated in patients with SCD. In addition, autopsy series have shown that an in situ thrombotic arteriopathy is seen in the majority of SCD patients with PHT. The purpose of this study is to determine whether markers of thrombin generation, platelet activation and inflammation are associated with PHT in SCD patients.Methods: This cross-sectional study was performed using a cohort of patients followed at the Sickle Cell Clinic at UNC-Chapel Hill. The pulmonary artery systolic pressure (PASP) was determined with a Doppler echocardiogram by applying the modified Bernoulli equation (PASP = 4V2 + right atrial pressure). Pulmonary hypertension was defined using an age-, sex- and BMI-adjusted reference range. Laboratory studies, including a complete blood count, soluble CD40 ligand [sCD40L] (a marker of inflammation and platelet activation) and markers of thrombin generation (thrombin-anti-thrombin complex [TAT], prothrombin fragment 1+2 [F1+2], and D-dimers) were obtained on all SCD subjects and on six healthy, race-matched control subjects without SCD. Wilcoxon Rank Sum Tests were used to compare median values in SCD patients with and without PHT, as well as between SCD patients and the control individuals.Results: Of the 76 subjects with SCD (SS = 56, SC = 9, Sβ0 = 4, Sβ+ = 7), PHT was found in 26 (34%). Compared with SCD patients without PHT, those with PHT had higher WBC counts (10.4 X 103/μL vs. 8.7 X 103/μL; p = 0.05). In addition, while PHT patients had consistently higher levels of such parameters as: D-dimers (1603 ng/mL [FEU] vs. 1233 ng/mL [FEU]; p = 0.3), TAT (7.05 μg/L vs. 5.7 μg/L; p = 0.8) and F1+2 (1.15 nmol/L vs. 0.9 nmol/L; p = 0.3), they failed to achieve statistical significance. On the other hand, the sCD40L level was lower (6.7 ng/mL vs. 7.6 ng/mL; p = 0.6) in the PHT group, although this difference was also not significant. In a second analysis, SCD patients had significantly higher levels of D-dimers (1251.5 ng/mL [FEU] vs. 318 ng/mL [FEU]; p = 0.02), sCD40L (7.3 ng/mL vs. 2.8 ng/mL; p = 0.0003), WBC count (9.2 X 103/μL vs. 7.1 X 103/μL; p = 0.02) and platelet count (399 X 103/μL vs. 251 X 103/μL; p = 0.002) when compared to control individuals. The TAT and F1+2 levels were also higher in SCD patients, although the differences were not significant.Conclusion: Compared to controls, SCD patients have increased thrombin generation, platelet activation and inflammation. In our cohort, SCD patients with PHT have higher levels of various markers of thrombin generation compared to patients without PHT. The lack of statistical significance is likely a result of the baseline elevation of these markers in SCD patients in steady state and as such, much higher increases in the levels of these markers and/or much larger sample sizes would be required to reveal a significant difference between both groups. This evidence of further activation of coagulation in SCD patients with PHT provides a rationale for clinical trials exploring the use of anticoagulation therapy in these patients.

Performance Prediction of a Turbodrill Based on the Properties of the Drilling Fluid

High-temperature geothermal well resource exploration faces high-temperature and high-pressure environments at the bottom of the hole. The all-metal turbodrill has the advantages of high-temperature resistance and corrosion resistance and has good application prospects. Multistage hydraulic components, consisting of stators and rotors, are the key to the turbodrill. The purpose of this paper is to provide a basis for designing turbodrill blades with high-density drilling fluid under high-temperature conditions. Based on the basic equation of pseudo-fluid two-phase flow and the modified Bernoulli equation, a mathematical model for the coupling of two-phase viscous fluid flow with the turbodrill blade is established. A single-stage blade performance prediction model is proposed and extended to multi-stage blades. A Computational Fluid Dynamics (CFD) model of a 100-stage turbodrill blade channel is established, and the multi-stage blade simulation results for different fluid properties are given. The analysis confirms the influence of fluid viscosity and fluid density on the output performance of the turbodrill. The research results show that compared with the condition of clear water, the high-viscosity and high-density conditions (viscosity 16 mPa∙s, density 1.4 g/cm3) will increase the braking torque of the turbodrill by 24.2%, the peak power by 19.8%, and the pressure drop by 52.1%. The results will be beneficial to the modification of the geometry model of the blade and guide the on-site application of the turbodrill to improve drilling efficiency.

Echocardiographic evaluation of pulmonary hypertension, right ventricular function, and right ventricular-pulmonary arterial coupling in patients with rheumatoid arthritis.

Rheumatoid arthritis (RA) patients are at increased risk for developing cardiovascular disease, including right heart failure. The evaluation of right ventricle (RV) using the relationship between tricuspid annular plane systolic excursion (TAPSE) and right ventricular systolic pressure (RVSP) is of clinical prognostic relevance. Mild echocardiographic pulmonary hypertension (ePH) has been associated with worse RV function. The aim of this study was to evaluate RV function as measured by TAPSE to RVSP ratio in rheumatoid arthritis patients compared to matched healthy controls. A case-control study with 67 RA patients aged 40 to 75 years that fulfilled the 2010 ACR/EULAR criteria and 45 matching controls was included. A transthoracic echocardiogram was performed to all patients. TAPSE was measured as the distance traveled from end-diastole to end-systole. RVSP was calculated using the modified Bernoulli equation. Comparisons were done using Chi-square and Mann-Whitney's U test or Student's t test. Patients with RA had significantly reduced ventricular function (TAPSE 23 [21-25] vs 25 [23-26], p = 0.033) and TAPSE/RVSP ratio was significantly lower in RA-patients than controls (TAPSE to RVSP ratio 0.809 [0.67-1.01] vs 0.933 [0.79-1.11], p = 0.009). RA-patients with mild ePH had similar RV function, evaluated by TAPSE, in comparison to RA-patients with normal RVSP. RA-patients had worse RV function measured by TAPSE and worse TAPSE/RVSP ratio than controls. Also, RA-patients with mild ePH had reduced right ventricular-pulmonary arterial coupling in comparison with patients with RA and normal RVSP. These echocardiographic findings could justify aggressive treatment for these patients and assess their evolution. Key Points • Right ventricular (RV) function and RV coupling with the pulmonary artery (RV-PA coupling) were worse in patients with RA in comparison to healthy controls. • Values of right ventricular systolic pressure (RVSP) were similar between RA-patients and non-RA controls. • Prevalence of normal RVSP, mild echocardiographic pulmonary hypertension (ePH), and pulmonary hypertension was similar between RA-patients and non-RA matched controls •Patients with RA and mild ePH had reduced RV-PA coupling in comparison with RA-patients with normal RVSP.

Abstract 14666: Association Between Right Ventricular Systolic Pressure and Health Status Following Transcatheter Aortic Valve Replacement

Introduction: Pulmonary hypertension (PH) was shown in multiple studies to be associated with an increased risk of mortality after transcatheter aortic valve replacement (TAVR). However, it is unclear if echocardiogram derived right ventricular systolic pressure (RVSP) is associated with health status outcomes in surviving patients after TAVR. We explored for an association between baseline RVSP and quality of life in patients before and after undergoing TAVR. Methods: We estimated RVSP by echocardiography using the modified Bernoulli equation in a single-center cohort of patients undergoing TAVR from 2012-2017 . Disease-specific health status was assessed at baseline and 1-month and 12-months after TAVR with the Kansas City Cardiomyopathy Questionnaire-Overall Summary Score (KCCQ-OS). We then explored the association between baseline RVSP and KCCQ-OS before and after TAVR using a linear mixed model with an interaction for time and baseline RVSP and adjusted for baseline mitral valve regurgitation and systolic blood pressure. Results: Among 485 patients who underwent TAVR (mean age 81.7±7.9 years, 54.8% men), baseline RVSP was 42±15 mmHg, and 73% had RVSP &gt;34 mmHg. After TAVR, mean RVSP decreased to 37±13 mmHg at 1 month and 36±14 mmHg at 12 months. Baseline KCCQ-OS was 46±25 and improved to 66.9±23.6 at 1 month and 69.5± 22.6 at 12 months. In the linear mixed model, there was a significant cross-sectional association between baseline RVSP and baseline KCCQ-OS, with higher RVSP associated with worse health status. However, baseline RVSP was not significantly associated with KCCQ-OS at 1 month or 12 months (Figure). Conclusions: RVSP is not associated with worse health status after TAVR. This suggests that while patients with high RVSP are at an increased risk for mortality after TAVR, surviving patients appear to have similar health status as those with normal RVSP.

SO084SILDENAFIL DRUG IN HEMODIALYSIS PATIENTS WITH PULMONARY HYPERTENSION

Abstract Background and Aims Pulmonary hypertension (PH) is not an uncommon progressive condition in prevalent hemodialysis (HD) patients, associated with high morbidity and mortality. Sildenafil drug has limited studies about the efficacy of the drug and optimal dose among prevalent HD patients with PH. Aim of the study to assess the effects of sildenafil drug on estimated Pulmonary Artery pressure value (ePAP) mmHg via transthoracic Doppler Echocardiography and 6-minute walk test ( 6MWT) among hemodialysis patients with pulmonary hypertension. Method Randomized, double-blind, placebo-controlled clinical trial, from December 2018 to May 2019, involving 60 eligible patients on regular adequate HD with PH, estimated Pulmonary Artery Pressure (ePAP) ≥35 mmHg via Doppler echocardiography. HD patients with mean age 52.6±10.8 year divided randomly into 3 groups: Group 1 (20 patients) received 25 mg sildenafil, group 2 (20 patients) received 50 mg sildenafil and group 3 (20 patients) who received placebo as daily dose treatment for 3 months duration. Every patient in the study was subjected to full history taking and clinical examination. Exclusion Criteria: Current treatment of pulmonary hypertension, patient with evident history of cardiac diseases or chronic pulmonary diseases or systemic autoimmune diseases, portal hypertension, HIV, patients with uncontrolled hypertension or severe anaemia or hypersensitivity to sildenafil, treatment with any drugs that may interact with sildenafil all were excluded from the study. Transthoracic echocardiography was done at the begging of the study and after three months in mid-week non-dialysis day for assessment of the change in ePAP, pulmonary artery pressure calculated using the modified Bernoulli equation, and assessment of right ventricular functions . Exercise capacity assessment by 6MWT to assess the clinical response to the drug, was done for every patient at the start of the study and after 3 months of treatment. Clinically meaningful change estimate for the 6MWT considered as increase more than 30 meters. Results Significant increase in mean of 6 MWT in both group 1,2 received 25 mg,50 mg sildenafil respectively after 3 m duration of treatment versus non-significant change in placebo group as basal 6 MWT was (171 ±45, 214 ±58, 175 ±39) meters in group 1,2 and placebo group respectively (p&amp;gt;0.05). Means 6 MWT post-treatment were (205 ±57, 258 ±59, 182 ±49) meters (P&amp;lt;0.001) in group 1, 2&amp;3 respectively, as post Hoc test results, showed significant increase in 6MWT2 in group 2 in comparison to group 1 and placebo group (P&amp;lt;0.01), as shown in figure (1).There was a significant decrease in e PAP in each group of studied groups after treatment (P&amp;lt;0.01). As mean basal ePAP1 measures were (48 ±9, 43.5 ±16, 48.5 ±12) mmHg in group 1,2,3 respectively (P&amp;gt;0.05).There were no significant differences between the studied groups regarding means of ePAP2 post-treatment were ( 42 ±9, 39 ±15, 44.5±8) mmHg in group 1,2,3 respectively (P&amp;gt;0.05). However, the degree of severity of PH was more improved after treatment duration with sildenafil as in group 1 there were 5 patients downgraded from moderate to mild and 2 patients downgraded from severe to moderate after treatment. In group 2 there were 4 patients downgraded from moderate to mild PH and 2 patients downgraded from severe to moderate PH. In 3rd group (placebo group) only one patient downgraded from moderate to mild PH. There were 4 patients dropouts from the study two of them from group 2 (receiving 50mg) due to sildenafil related side effects appeared through the study. Conclusion This a clinical trial confirmed the efficiency of both 50mg and 25mg sildenafil daily dose in reducing e PAP and improving functional exercise capacity in chronic haemodialysis patients with pulmonary hypertension disease.

Analytical and numerical modelling of high-velocity impact on multilayer alumina/aramid fiber composite ballistic shields: Improvement in modelling approaches

In this paper, analytical and numerical models were developed to simulate the perforation of ceramic-composite targets by small-caliber projectiles. The modified Bernoulli equation has been implemented in a new analytical model to simulate the interaction between projectile and ceramic tile and an energy formulation based on the wave propagation theory has been adopted to describe energy absorption of the composite backing. The numerical model, developed with the software LS-DYNA, is based on a full-Lagrangian finite-element analysis. Both models yielded good agreement with the performed impact tests on pure alumina single tile and on multilayer Al2O3-Kevlar 29/epoxy using actual 7.62 mm NATO Ball projectile.

The value of three-dimensional echocardiography in the evaluation of cor triatrium sinister

Introduction Cor triatrium sinister is a very rare congenital heart disease in which the pulmonary veins enter a proximal accessory left atrial chamber that is separated from a distal true left atrial chamber by a fibromuscular membrane presenting one or more ostia. Its incidence in the adulthood is extremely rare. Adult patients are symptomatic in case the orifice across the membrane becomes obstructive mimicking a mitral stenosis. It has been reported that severe obstruction is present if maximum doppler velocity across the orifice is more than 2 m/s.1 However, in a review of case series no correlation could be found between the pressure gradient across the fenestration and the clinical symptoms.2 We report the case of a symptomatic adult female with obstructive cor triatrium in whom the intraoperative three-dimensional transesophageal echocardiography (3D TEE) revealed the severity of obstruction in contrast to the mild intraoperative pressure gradients. Methods A 34-year-old female was scheduled for surgical repair of a cor triatrium sinister. The symptoms of dyspnea had increased during the last months (NYHA III) which resulted in the echocardiographic diagnosis. The mean pressure gradient across the orifice was estimated 6 mmHg at rest and 18 mmHg at effort using modified Bernoulli equation. There were no associated cardiac abnormalities and no signs of pulmonary hypertension. The patient gave written consent to present her case. Results The induction of anesthesia was performed with the aim to keep hemodynamic stability. The intraoperative TEE confirmed the diagnosis. Color flow across the orifice showed an aspect of rather laminar flow. The mean pressure gradient across the sole orifice was 2 mmHg.Three-dimensional en face view of the membrane permitted offline analysis of the lesion in several orthogonal planes and measurement of the effective opening area of the orifice which was 1.45 cm2 (Fig 1). Discussion This case illustrates that pressure gradient across an obstructive cor triatrium may underestimate the true severity of the lesion as the blood flow may be low through the channel. Therefore, 3D echocardiography should be routinely performed in patients with cor triatrium in order to measure the exact maximal fenestration orifice area.

YES, YOU CAN USE THE TRICUSPID REGURGITATION SIGNAL FOR THE RIGHT VENTRICULAR TO RIGHT ATRIAL GRADIENT, NO MATTER HOW SEVERE THE TRICUSPID REGURGITATION: A SIMULTANEOUS ECHOCARDIOGRAPHY: CATHETERIZATION STUDY

The performance of the modified Bernoulli equation to estimate the RV-RA pressure gradient by continuous wave Doppler in severe tricuspid regurgitation (TR) is not known. Simultaneous continuous wave (CW) Doppler of the TR jet was prospectively obtained at time of cardiac catheterization in seven

Abstract 17391: Use of Contrast-Enhanced Echocardiography for Evaluating Pulmonary Artery Pressure

Introduction: Pulmonary artery systolic pressure (PASP) can be derived from maximum tricuspid regurgitation velocity (TRV) obtained from echo using a modified Bernoulli equation. However, PASP from an unenhanced echo only modestly correlates to invasively measured PASP. This study evaluates whether the accuracy of PASP from an echo can be improved by using contrast agents. Methods: Ninety consecutive patients undergoing clinically indicated right heart catheterization were recruited to perform simultaneous echo. TRV was measured in an echo unenhanced (UE), with agitated saline (AgS), and with echo contrast (EC) (routinely injected centrally, and peripherally in 21 patients). PASP was then calculated using the formula PASP=4(TRV 2 )+RAP, where RAP was estimated on echo by inferior vena cava collapsibility. Data was analyzed using paired t-test and linear regression (JMP Pro13). Results: Average age was 54 (±13) years with 58% males, 73% heart transplant recipients, and 38% with pulmonary hypertension. UE PASP was significantly lower than RHC PASP with a mean difference of -6.09 mm Hg (p&lt;0.001) and correlation coefficient of 0.57 (p&lt;0.001). In comparison, AgS PASP had a smaller mean difference of 0.41 mm Hg (p=0.641) and a higher correlation coefficient of 0.73 (p&lt;0.001). EC-enhanced echo also yielded a smaller mean difference (central: -1.82 mm Hg with p=0.049; peripheral: -3.21 mm Hg with p=0.095) and an even higher correlation coefficient (central: r=0.74; peripheral: r=0.81). Number of patients with accurate PASP from echo (defined as PASP difference &lt;10 mm Hg between echo and RHC) was improved from 65% (UE) to 77% (AgS), 82% (EC-central), and 71% (EC-peripheral). Conclusion: Echo with agitated saline yielded the closest mean PASP compared to invasivePASP, whereas echo with peripherally administered EC yielded the highest correlation coefficient. Echo enhancement with either Ags or EC can improve the accuracy of the estimated PASP compared to UE studies.

An analytical model for ballistic impacts against ceramic tiles

An improved analytical model able to simulate normal ballistic impacts of blunt shaped equivalent projectiles against ceramic tiles, without any backing plate, is described. The projectile is modelled as a rigid body with a deformable tip that can be eroded when in contact with the ceramic, that in turn is eroded and comminuted when critical conditions are reached. The modified Bernoulli equation relates the velocities of the deformable projectile and the ceramic assuming a hydrodynamic behaviour of the parts in contact, in proximity of the impact area. Innovative contributions are added in order to reproduce also low velocity impacts (below the Bernoulli limit), a range in which the modified Bernoulli equation can’t be applied. The model is compared with experimental data both from the literature and from ballistic tests, with actual bullets, performed by authors, predicting the residual velocity and the residual mass of the projectile (when the data is available), with also an analysis of the evolution in time of the parameters.

Association of elevated pulmonary artery systolic pressure with stroke and systemic embolic events in patients with hypertrophic cardiomyopathy

BackgroundEchocardiographically estimated pulmonary artery systolic pressure (PASP) is a non-invasive widely available method that is used to estimate pulmonary arterial pressure. Although elevated PASP predicts mortality in patients with hypertrophic cardiomyopathy (HCM), the relationship between PASP and embolic events is unclear. This study aimed to determine whether elevated PASP is associated with stroke and systemic embolic events in a tertiary referral HCM cohort. MethodsThis study included 374 clinically diagnosed patients with HCM. PASP was estimated from tricuspid regurgitant jet velocity using the modified Bernoulli equation. ResultsThe median (interquartile range) PASP was 33 (28–37) mm Hg, and elevated PASP (>40mmHg) was observed in 66 (17.6%) patients. Seventeen of the 66 (25.8%) patients with elevated PASP and 24 of the 308 (7.8%) patients without elevated PASP experienced stroke and systemic embolic events during the 10.3±7.4years of follow-up (log-rank P<0.001). Multivariable analysis showed that age at diagnosis, atrial fibrillation, and PASP >40mmHg (adjusted hazard ratio, 2.59; 95% confidence interval, 1.31–5.12; P=0.006) were independently associated with embolic events. ConclusionsIn addition to age and atrial fibrillation, PASP estimated by Doppler echocardiography could help embolic risk stratification in patients with HCM.