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Computational fluid dynamics (CFD) are the gold standard in studying blood flow dynamics. However, CFD results are dependent on the boundary conditions and the computation model. The purpose of this study was to validate CFD methods using comparison with actual measurements of the blood flow vector obtained with four-dimensional (4D) flow magnetic resonance imaging (MRI). 4D Flow MRI was performed on a healthy adult and a child with double-aortic arch. The aortic lumen was segmented to visualize the blood flow. The CFD analyses were performed for the same geometries based on three turbulent models: laminar, large eddy simulation (LES), and the renormalization group k–ε model (RNG k–ε). The flow-velocity vector components, namely the wall shear stress (WSS) and flow energy loss (EL), of the MRI and CFD results were compared. The flow rate of the MRI results was underestimated in small vessels, including the neck vessels. Spiral flow in the ascending aorta caused by the left ventricular twist was observed by MRI. Secondary flow distal to the aortic arch was well realized in both CFD and MRI. The average correlation coefficients of the velocity vector components of MRI and CFD for the child were the highest for the RNG k–ε model (0.530 in ascending aorta, 0.768 in the aortic arch, 0.584 in the descending aorta). The WSS and EL values of MRI were less than half of those of CFD, but the WSS distribution patterns were quite similar. The WSS and EL estimates were higher in RNG k–ε and LES than in the laminar model because of eddy viscosity. The CFD computation realized accurate flow distal to the aortic arch, and the WSS distribution was well simulated compared to actual measurement using 4D Flow MRI. However, the helical flow was not simulated in the ascending aorta. The accuracy was enhanced by using the turbulence model, and the RNG k–ε model showed the highest correlation with 4D Flow MRI.

Chronic thromboembolic pulmonary hypertension is caused by incomplete resolution and organization of thrombi. Blood flow dynamics are involved in thrombus formation; however, only a few studies have reported on pulmonary artery blood flow dynamics in patients with chronic thromboembolic pulmonary hypertension. Furthermore, the effects of treatment interventions on pulmonary artery blood flow dynamics are not fully understood. The aim of the study was to evaluate pulmonary artery blood flow dynamics in patients with chronic thromboembolic pulmonary hypertension before and after pulmonary endarterectomy and balloon pulmonary angioplasty, using computational fluid dynamics. We analyzed patient-specific pulmonary artery models of 10 patients with chronic thromboembolic pulmonary hypertension and three controls using computational fluid dynamics. In patients with chronic thromboembolic pulmonary hypertension, flow velocity and wall shear stress in the pulmonary arteries were significantly decreased, and the oscillatory shear index and blood stagnation volume were significantly increased than in controls. Pulmonary endarterectomy induced redistribution of pulmonary blood flow and improved blood flow dynamics in the pulmonary artery. Balloon pulmonary angioplasty improved pulmonary blood flow disturbance, decreased blood flow stagnation, and increased wall shear stress, leading to vasodilatation of the distal portion of the pulmonary artery following balloon pulmonary angioplasty treatment.

Blood flow imaging is a novel technology in cardiovascular medicine and surgery. Today, two types of blood flow imaging tools are available: measurement-based flow visualization including 4D flow MRI (or 3D cine phase-contrast magnetic resonance imaging), or echocardiography flow visualization software, and computer flow simulation modeling based on computational fluid dynamics (CFD). MRI and echocardiography flow visualization provide measured blood flow but have limitations in temporal and spatial resolution, whereas CFD flow calculates the flow according to assumptions instead of flow measurement, and it has sufficiently fine resolution up to the computer memory limit, and it enables even virtual surgery when combined with computer graphics. Blood flow imaging provides profound insight into the pathophysiology of cardiovascular diseases, because it quantifies and visualizes mechanical stress on the vessel walls or heart ventricle. Wall shear stress (WSS) is a stress on the endothelial wall caused by the near wall blood flow, and it is thought to be a predictor of atherosclerosis progression in coronary or aortic diseases. Flow energy loss (EL) is the loss of blood flow energy caused by viscous friction of turbulent diseased flow, and it is expected to be a predictor of ventricular workload on various heart diseases including heart valve disease, cardiomyopathy, and congenital heart diseases. Blood flow imaging can provide useful information for developing predictive medicine in cardiovascular diseases, and may lead to breakthroughs in cardiovascular surgery, especially in the decision-making process.

Background Left ventricular outflow tract stenosis and atrioventricular valve regurgitation are often problems encountered in adulthood after complete atrioventricular septal defect repair. The surgical approach and indications for managing long-term outcomes such as left atrioventricular valve regurgitation and left ventricular outflow tract stenosis after complete atrioventricular septal defect repair have been discussed. Case presentation A 23-year-old woman with intellectual disability was diagnosed with complete atrioventricular septal defect and underwent two-patch repair without cleft closure in childhood. Follow-up examination in adulthood demonstrated moderate left-sided atrioventricular valve regurgitation and left ventricular outflow tract stenosis with a circumferential ridge (peak velocity, 3.7 m/s; pressure gradient, 54 mmHg). Intraoperative findings showed a circumferential ridge under the aortic valve, and we removed the ridge. In addition, a cleft was present at the anterior leaflet, and we completely closed the cleft. Anticoagulation therapy was not initiated, and no embolic complications occurred. Follow-up echocardiography demonstrated no ridge under the aortic valve and only mild-range left AVVR. Conclusions We successfully performed surgical treatment without valve replacement or anticoagulation therapy in a patient with poor medical compliance. Delayed reoperation leads to degeneration of the valve structure and makes more difficult to repair. Atrioventricular valve regurgitation should be evaluated in combination with based on the etiology of the regurgitation especially cleft related or not, in addition to the dilatation annulus, cleft size, and depth of the leaflet coaptation depth, and associated other valve diseases.

A 38-year-old woman presented with exertional dyspnea and chest compression. She had undergone repair of congenital supravalvular aortic stenosis at 8 years of age. Contrast-enhanced computed tomography showed re-stenosis in the ascending aorta, bilateral coronary arterial aneurysm, and a highly thickened left ventricular wall. Release of stenosis was necessary to avoid left ventricular functional deterioration; however, it could cause demand–supply mismatch in coronary flow due to substantial left ventricular hypertrophy. Sufficient statistical evidence was not available in this situation; therefore, computerized virtual surgery based on computational fluid dynamics (CFD) was performed to predict the postoperative hemodynamics. Consequently, root replacement with in situ Carrel patch coronary reconstruction was considered a better option than coronary artery graft bypass in the left-side coronary flow supply. The patient underwent root replacement with in situ Carrel patch coronary reconstruction as planned based on CFD without any complication and was discharged 15 days postoperatively.

Computational fluid dynamics (CFD) analysis using computed tomography images can reveal the details of the blood flow in cardiovascular disease. In double aortic arch, it is difficult to assess the hemodynamics because of the strong influence of various anatomical features, such as the angle of the aortic bifurcation. In the present study, we reported that CFD analysis is a valuable method for hemodynamic assessment in patients with double aortic arch.

Background Recently, improvements in the repair of tetralogy of Fallot have increased the need for reoperation in adulthood, and it’s not rare that these reoperation candidates suffer from biventricular failure. However, there are no firm treatment guidelines, and each country, and even each facility, treats each case individually. Case presentation We report the successful staged treatment of pulmonary regurgitation and pacemaker-induced cardiomyopathy with biventricular failure in adulthood in a case of complete atrioventricular block after tetralogy of Fallot repair in childhood. We planned a staged therapeutic strategy with preoperative left ventricular volume reduction with medication, following surgical pulmonary valve replacement concomitant epicardial lead implantation on the lateral basal wall, placed just beneath the generator pocket through 3rd intercostal space. in addition to postoperative intervention with a defibrillator to adjust cardiac resynchronization therapy, resulted in improvement of symptoms. Conclusion In a patient with biventricular failure after TOF repair, a staged treatment strategy involving medication, PVR, and CRT with a combination of epicardial and intravenous leads could be a useful treatment worth trying before heart transplantation.

Background Portal vein stenosis develops in 3.4–14% of split liver transplantation 1 – 3 and its early detection and treatment are essential to achieve long-term graft survival, 2 – 5 although the diagnostic capability of conventional modalities such as Doppler ultrasound and computed tomography is limited. 1 , 4 , 5 Methods This study used computational fluid dynamics to analyze portal vein hemodynamics in the management of post-transplant portal vein stenosis. To perform computational fluid dynamics analyses, three-dimensional portal vein model was created using computed tomographic DICOM data. The inlet flow condition was set according the flow velocity measured on Doppler ultrasonography. Finally, portal vein flow was simulated on a fluid analysis software (Software Cradle, Japan). Results An 18-month-old girl underwent liver transplantation using a left lateral graft for biliary atresia. At the post-transplant 1-week evaluation, the computational fluid dynamics streamline analysis visualized vortices and an accelerated flow with a velocity ratio < 2 around the anastomotic site. The wall shear stress analysis revealed a high wall shear stress area within the post-anastomotic portal vein. At the post-transplant 6-month evaluation, the streamline analysis illustrated the increased vortices and worsening flow acceleration to reach the proposed diagnostic criteria (velocity ratio > 3:1). 3 , 5 The pressure analysis revealed a positive pressure gradient of 3.8 mmHg across the stenotic site. Based on the findings, the patient underwent percutaneous transhepatic portal venoplasty with balloon dilation. The post-treatment analyses confirmed the improvement of a jet flow, vortices, a high wall shear stress, and a pressure gradient. Discussion The computational fluid dynamics analyses are useful for prediction, early detection, and follow-up of post-transplant portal vein stenosis and would be a promising technology in post-transplant management.

Mitral valve morphology after mitral valve surgery affects postoperative intraventricular flow patterns and long-term cardiac performance. We visualized ventricular flow by echocardiography vector flow mapping (VFM) to reveal the impact of different mitral valve procedures. Eleven cases of mechanical mitral valve replacement (nine in the anti-anatomical and two in the anatomical position), three bioprosthetic mitral valve replacements, and four mitral valve repairs were evaluated. The mean age at the procedure was 57.4 ± 17.8 year, and the echocardiography VFM in the apical long-axis view was performed 119.9 ± 126.7 months later. Flow energy loss (EL), kinetic pressure (KP), and the flow energy efficiency ratio (EL/KP) were measured. The cases with MVR in the anatomical position and with valve repair had normal vortex directionality (“Clockwise”; N  = 6), whereas those with MVR in the anti-anatomical position and with a bioprosthetic mitral valve had the vortex in the opposite direction (“Counterclockwise”; N  = 12). During diastole, vortex direction had no effect on EL (“Clockwise”: 0.080 ± 0.025 W/m; “Counterclockwise”: 0.083 ± 0.048 W/m; P  = 0.31) or KP (“Clockwise”: 0.117 ± 0.021 N; “Counterclockwise”: 0.099 ± 0.057 N; P  = 0.023). However, during systole, the EL/KP ratio was significantly higher in the “Counterclockwise” vortex than that in the “Clockwise” vortex (1.056 ± 0.463 vs. 0.617 ± 0.158; P  = 0.009). MVP and MVR with a mechanical valve in the anatomical position preserve the physiological vortex, whereas MVR with a mechanical valve in the anti-anatomical position and a bioprosthetic mitral valve generate inefficient vortex flow patterns, resulting in a potential increase in excessive cardiac workload.