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    Computer-generated Clinical Decision-making in the Treatment of Pulmonary Atresia with Intact Ventricular Septum
    (Springer, 2025) Yildirim, Canberk; Ural, Berk; Odemis, Ender; Donmazov, Samir; Pekkan, Kerem
    Purpose Pulmonary atresia with intact ventricular septum is a multifactorial disease requiring complex surgeries. The treatment route is determined based on the right ventricle (RV) size, tricuspid annulus size and coronary circulation dependency of RV. Since multiple parameters influence the post-operative success, a personalized decision-making based on computed hemodynamics is hypothesized to improve the treatment efficacy. Methods A lumped parameter cardiovascular model is developed to calculate the hemodynamics of virtual patients which are generated by statistical distribution of circulation parameters. Four cohorts each with 30 digital patients are grouped based on RV size. For each patient, biventricular and one-and-half ventricle (1.5 V) repair were applied in silico and assessed via pressure, flow and saturations computed for every organ bed. Results Biventricular and 1.5 V repair yield significant increase in the pulmonary flow and oxygen saturation for all patients compared to the pre-operative state (p-values < 0.001). Approximately 30% of generated patients failed to meet the sufficient saturation and flow following biventricular repair and were directed to 1.5 V repair. However, 14% of these 1.5 V repair patients failed post-operatively, requiring Fontan completion. Based on the pre-determined hemodynamics criteria, this study implies that patients having RV sizes larger than 22 ml/m(2) are likely to undergo successful biventricular repair. Conclusion Pending further clinical trials, computational pre-interventional planning has the potential to screen patients that would not optimally fit to the traditional pathway prior to in vivo execution by providing personalized hemodynamic outcome. Statistical approach allows in silico clinical trials, useful for diseases with low patient numbers.
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    Evaluation of the total hydrodynamic energy loss using 4D flow MRI in a case with Fontan failure
    (Cell Press, 2024) Odemis, Ender; Gumus, Terman; Aka, Ibrahim Basar; Ozkok, Sercin; Pekkan, Kerem
    Fontan Failure (FF) is a common problem for single-ventricle patients as they reach adulthood. Although several mechanisms may cause FF, an optimized blood flow stream through the surgical conduits is essential to avoid excessive energy loss (EL). Recent clinical studies showed EL is related to the quality of life, exercise capacity, and hepatic function since the single-ventricle feeds pulmonary and systemic circulation serially. 4D flow MRI effectively estimates EL in Fontan circulation and allows clinicians to compare the effectiveness of the treatment strategy concerning pre-intervention. Here, we present 26-year-old women with FF who had normal cardiac catheterization findings and were treated according to high EL definitions that are measured through 4D flow MRI.
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    Novel small-sized ePTFE valves for neonatal RVOT reconstruction: an in-vitro investigation
    (Elsevier Sci Ltd, 2025) Aka, Ibrahim Basar; Altin, Husnu Firat; Aka, Bahaeddin Umur; Turkoz, Riza; Pekkan, Kerem
    Small-sized right ventricle to pulmonary artery conduits are hindered by calcification, degeneration, or infective endocarditis and face limited availability. Valved conduits of expanded polytetrafluoroethylene leaflets offer a promising path toward enhanced longevity and performance. This in-vitro study introduces innovative expanded polytetrafluoroethylene valve designs for small-sized conduits.Three bicuspid and three tricuspid expanded polytetrafluoroethylene leaflets designed for size 12 mm were tested using an in-vitro pediatric right-heart mockup loop and compared with our baseline leaflet design. Polyvinylchloride was used to create a transparent tube for visual access. Regurgitation rates, pressure gradients, effective orifice area under 0.5-3 L/min cardiac outputs, and 100-150beats/min heart rates are measured. Mechanical differences between expanded polytetrafluoroethylene and polyvinylchloride are investigated through biaxial strain tests. In newborn hemodynamic conditions, 0.5-1 L/min cardiac output, bileaflet valves demonstrated regurgitation rates below 20%, and two tricuspid models maintained regurgitation rates below 15% with gradients below 25 mmHg. In infant conditions, 1-3 L/min output, the regurgitation rates of trileaflet models were below 20%, with gradients consistently below 35 mmHg. The fully coapting bileaflet model showed a regurgitation rate of less than 15% and a gradient below 30 mmHg across newborn and infant conditions. A circumferential difference of less than 0.12 mm was detected between expanded polytetrafluoroethylene and polyvinylchloride. Both the fully coapting bileaflet and redundant trileaflet configurations can be integrated in the small conduits. Polyvinylchloride can be an alternative to expanded polytetrafluoroethylene tube graft in in-vitro studies, allowing visual access to assess leaflet kinematics.
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    Optimizing percutaneous pulmonary valve implantation with patient-specific 3D-printed pulmonary artery models and hemodynamic assessment
    (Frontiers Media SA, 2023) Ödemiş, Ender; Aka, İbrahim Başar; Ali, Mhd Homam Aljah; Gümüş, Terman; Pekkan, Kerem
    Abstract Background: Percutaneous pulmonary valve implantation (PPVI) has emerged as a less invasive alternative for treating severe pulmonary regurgitation after tetralogy of Fallot (TOF) repair in patients with a native right ventricular outflow tract (RVOT). However, the success of PPVI depends on precise patient-specific valve sizing, the avoidance of oversizing complications, and optimal valve performance. In recent years, innovative adaptations of commercially available cardiovascular mock loops have been used to test conduits in the pulmonary position. These models are instrumental in facilitating accurate pulmonic valve sizing, mitigating the risk of oversizing, and providing insight into the valve performance before implantation. This study explored the utilization of custom-modified mock loops to implant patient-specific 3D-printed pulmonary artery geometries, thereby advancing PPVI planning and execution. Material and Methods: Patient-specific 3D-printed pulmonary artery geometries of five patients who underwent PPVI using Pulsta transcatheter heart valve (THV) ® were tested in a modified ViVitro pulse duplicator system®. Various valve sizes were subjected to 10 cycles of testing at different cardiac output levels. The transpulmonary systolic and regurgitation fractions of the valves were also recorded and compared. Results: A total of 39 experiments were conducted using five different patient geometries and several different valve sizes (26, 28, 30, and 32 mm) at 3, 4, and 5 L/min cardiac output at heart rates of 70 beats per minute (bpm) and 60/40 systolic/diastolic ratios. The pressure gradients and regurgitation fractions of the tested valve sizes in the models were found to be similar to the pressure gradients and regurgitation fractions of valves used in real procedures. However, in two patients, different valve sizes showed better hemodynamic values than the actual implanted valves. Discussion: The use of 3D printing technology, electromagnetic flow meters, and the custom-modified ViVitro pulse duplicator system® in conjunction with patient-specific pulmonary artery models has enabled a comprehensive assessment of percutaneous pulmonic valve implantation performance. This approach allows for accurate valve sizing, minimization of oversizing risks, and valuable insights into hemodynamic behavior before implantation. The data obtained from this experimental setup will contribute to advancing PPVI procedures and offer potential benefits in improving patient outcomes and safety. 2024 Odemis, AKA, Ali, Gumus and Pekkan.