Pulsatility Index in Different Modifications of Fontan Palliation: An Echocardiographic Assessment

Reza Shabanian,Parvin Akbari Asbagh,Abdullah Sedaghat,Minoo Dadkhah,Zahra Esmaeeli,Aliyeh Nikdoost,Manizheh Ahani,Mitra Rahimzadeh,Alireza Dehestani,Mohammad Ali Navabi 한국심초음파학회 2022 Journal of Cardiovascular Imaging (J Cardiovasc Im Vol.30 No.2

BACKGROUND: Adding pulsation to the Fontan circulation might change the fate of patients palliated by this procedure. Our aim was to compare the pulsatility index (PI) of the pulmonary artery (PA) between the various modifications of Fontan palliation. METHODS: Doppler-derived PI was measured in PA branches of a cohort of 28 patients palliated by 6 modifications of Fontan procedure. A group of normal individuals was included for comparison. RESULTS: Atriopulmonary connection (APC) group had the highest PA branches PI and statistically was close to the PI of the normal individuals (right pulmonary artery [RPA] PI of 1.58 vs. 1.63; p = 0.99 and left pulmonary artery [LPA] PI of 1.54 vs. 1.68; p = 0.46, respectively). The lowest PA branches PI was seen in the group of extracardiac total cavopulmonary connection (RPA PI of 0.62 and LPA PI of 0.65). Other 4 modifications including the extracardiac conduit with oversewn pulmonary valve, extracardiac conduit with preserved adjusted antegrade flow, extracardiac conduit from inferior vena cava onto the rudimentary right ventricle and lateral tunnel had a mean “RPA and LPA” PI of “1.19 and 1.17”, “1.16 and 1.11”, “1.13 and 1.11”, “0.82 and 0.84”, respectively. The modified Dunnett's post hoc test has shown a significant statistical decline in PI of all modifications compared to the normal individuals except for the APC group. CONCLUSIONS: Fontan palliated patients in different groups of surgical modification showed a spectrum of Doppler-derived PI with the highest amounts belong to the groups of pulsatile Fontan.

Echocardiographic Assessment of Pulmonary Arteries Pulsatility Index in Fontan Circulation

Reza Shabanian,Mohammad Reza Mirzaaghayan,Minoo Dadkhah,Mehdi Hosseini,Mitra Rahimzadeh,Parvin Akbari Asbagh,Mohammad Ali Navabi 한국심초음파학회 2015 Journal of Cardiovascular Imaging (J Cardiovasc Im Vol.23 No.4

Background: Late complications after Fontan procedure may be due to the absence of pump and pulsatile pulmonary blood flowin this type of palliation. Our aim was to quantify the degree of pulsation by echocardiographic method in patients with extracardiactotal cavopulmonary connection (ECTCPC) in comparison with biventricular circulation and few cases of pulsatile Fontan. Methods: In a case series study, pulsatility index (PI) derived by echocardiographic method were compared between 20 patientswith ECTCPC, 6 patients with pulsatile Fontan and 18 normal individual aged 4 to 20 years old. All patients were in New YorkHeart Association class of I and there was no report of complication. Results: In patients with ECTCPC pulmonary artery branches Doppler flow study showed lower peak and mean velocitiescompared to the pulsatile Fontan and normal groups. ECTCPC patients had PI of 0.59 ± 0.14 and 0.59 ± 0.09 for right and leftpulmonary arteries (RPA and LPA) respectively. PI was higher in patients with preserved antegrade flow (RPA PI = 0.94 ± 0.26,LPA PI = 0.98 ± 0.27) and in normal individuals (RPA PI = 1.59 ± 0.12, LPA PI = 1.64 ± 0.17) for both branches (p = 0.000). Conclusion: Using a Doppler derived index for pulsatility, patients with ECTCPC had the least pulsation. The pulmonary arteryflow pattern in patients with preserved antegrade flow showed higher pulsatility indices in both branches. Normal individualshad the greatest pulsatility index.

Computational fluid dynamics modeling of hydrogen production in an autothermal reactor: Effect of different thermal conditions

Sayed Reza Shabanian,Masoud Rahimi,Amin Amiri,Shahram Sharifnia,Ammar Abdulaziz Alsairafi,정재학,김우경 한국화학공학회 2012 Korean Journal of Chemical Engineering Vol.29 No.11

A numerical model was developed and validated to simulate and improve the reforming efficiency of methane to syngas (CO+H2) in an autothermal reactor. This work was undertaken in a 0.8 cm diameter and 30 cm length quartz tubular reactor. The exhaust gas from combustion at the bottom of reactor was passed over a Ru/γ-Al2O3 catalyst bed. The Eddy Dissipation Concept (EDC) model for turbulence-chemistry interaction in combination with a modified standard k-ε model for turbulence and a reaction mechanism with 23 species and 39 elementary reactions were considered in the combustion model. The pre-exponential factors and activation energy values for the catalyst (Ru) were obtained by using the experimental results. The percentage of difference between the predicted and measured mole fractions of the major species in the exhaust gas from combustion and catalyst bed zones was less than 5.02% and 7.73%,respectively. In addition, the results showed that the reforming efficiency, based on hydrogen yield, was increased with increase in catalyst bed’s thermal conductivity. Moreover, an enhancement of 4.34% in the reforming efficiency was obtained with increase in the catalyst bed wall heat flux from 0.5 to 2.0 kW/m2.

Prediction and optimization of hydrogen yield and energy conversion efficiency in a non-catalytic filtration combustion reactor for jet A and butanol fuels

Seyed Reza Shabanian,Sanaz Edrisi,Fatemeh Vahdat Khoram 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.8

Hydrogen production is one of main subjects in fuel cells. The traditional method of synthesis gas production is based on fuel reforming using catalysts. The main problem of these methods is sensitivity and fast degradation of catalysts especially when fuels with high sulfur content are used. A new technique for hydrogen production is fuelreforming using non-catalytic filtration combustion in porous media reactors. Various experimental works have been carried out to increase hydrogen production under different operating conditions such as inlet fuel velocity and equivalence ratio. First, we investigated the ability of adaptive neuro fuzzy inference system (ANFIS) for predicting the filtration combustion characteristics. Four distinct ANFIS models were developed for estimating the hydrogen yield and energy conversion efficiency for fuels of jet A and butanol. Eight different membership functions of dsigmf, gauss2mf, gaussmf, gbellmf, pimf, psigmf, trapmf and trimf were tested for training of the ANFIS networks. The results showed that the RMSE of the best developed ANFIS models for estimating of the hydrogen yield of jet fuel, hydrogen yield of butanol, conversion efficiency of jet fuel and conversion efficiency of butanol were 1.399, 1.213, 0.508 and 2.191, respectively. Moreover the R2 values of 0.998, 0.998, 0.999 and 0.999 were obtained for predicting the above mentioned variables, respectively. In the second step, a novel algorithm based on imperialist competitive algorithm (ICA) was used for optimization of hydrogen yield and energy efficiency. The maximum value of hydrogen yield and energy efficiency was 50.46% and 67.88% for jet A and 47.27% and 96.93% for butanol, respectively. The results showed that the imperialist competitive algorithm is an efficient and powerful algorithm to optimize combustion processes.

CFD Study and RSM Optimization of Acetylene Production in Partial Oxidation Process

Ghayour Maliheh Saravani,Shabanian Seyed Reza 한국화학공학회 2024 Korean Journal of Chemical Engineering Vol.41 No.3

The present study aims to increase the selectivity of C 2 H 2 in the partial oxidation process of methane, employing design of experiments (DOE) and computational fl uid dynamics (CFD). Central composite design is used to design tests, and analysis of variance is performed to evaluate the percentage of contribution of operating factors on system performance. The operating factors considered in the analysis are preheating temperature, O 2 /CH 4 ratio, and inlet velocity. The system responses are selectivity of C 2 H 2 and conversion of CH 4 . Furthermore, an optimization method using response surface methodology is utilized to determine the optimal values of operating factors that lead to the best system performance. The fi ndings indicate that increasing the preheating temperature and O 2 /CH 4 ratio boosts the selectivity of C 2 H 2 and reduces the methane conversion percentage, while increasing the inlet velocity has the opposite eff ect. The optimization method indicates that the maximum selectivity of C 2 H 2 is achieved with conversion of CH 4 of 95% under optimal conditions, namely preheating temperature of 1151.13 K, inlet velocity of 222.8 m/s, and O 2 /CH 4 ratio of 0.59.