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Hemodynamics in total cavopulmonary connections (TCPCs) are closely linked to patient outcomes. Previous studies have simplified assessments by focusing solely on the TCPC itself, overlooking the effects of upstream flow mixing. Consequently, the impact of upstream flow mixing on TCPC hemodynamics remains poorly understood. In this study, we quantified for the first time the effect of flow mixing from all vessels upstream of the TCPC. Hemodynamic metrics were obtained using a cutting-edge computational platform that considers patient-specific TCPC anatomy, peripheral vessels upstream of the TCPC, and corresponding flow data. Results showed that ignoring upstream flow mixing from the upper and lower body could lead to significant errors in calculating hepatic flow distribution—5.0% ± 5.9% and 14.4% ± 10.9%, respectively—but not in power loss (PL) or resistance throughout the TCPC. Interestingly, flow mixing from the upper body induces an additional 25.8 ± 16.8% PL beyond the losses within the TCPC itself, which could inspire innovative clinical treatments to improve patient outcomes. Our study underscores the critical need to account for upstream flow mixing from both the upper and lower body in TCPC hemodynamic assessments. Accurately simulating this mixing requires estimating the flow rates of peripheral vessels. We explored radius-based flow-splitting methods to achieve this, finding that the square law aligns most closely with patient data for lower-body vessels, while the fourth-power law yields satisfactory results for upper-body vessels. These findings could significantly impact clinical practices in Fontan hemodynamic assessment. [ABSTRACT FROM AUTHOR]

The article focuses on a case of Fontan circulatory failure due to conduit angulation stenosis in a 32-year-old woman who had undergone Fontan surgery 27 years prior. Topics include the diagnosis and imaging techniques used to identify conduit angulation and stenosis, the surgical intervention involving conduit replacement with a FEP-Ringed Gore-Tex graft, and the post-operative improvements in the patient's oxygen saturation and cardiac function.

Aims To characterize the dynamic nature of the left ventricular outflow tract (LVOT) geometry and flow rate in patients following transcatheter mitral valve replacement (TMVR) with anterior leaflet laceration (LAMPOON) and derive insights to help guide future patient selection. Methods and results Time-resolved LVOT geometry and haemodynamics were analysed with post-procedure computed tomography and echocardiography in subjects (N  = 19) from the LAMPOON investigational device exemption trial. A novel post hoc definition for LVOT obstruction was employed to account for systolic flow rate and quality of life improvement [obstruction was defined as LVOT gradient > 30 mmHg or LVOT effective orifice area (EOA) ≤ 1.15 cm2]. The neo-LVOT and skirt neo-LVOT were observed to vary substantially in area throughout systole (64  ±  27% and 25  ±  14% change in area, respectively). The peak systolic flow rate occurred most commonly just prior to mid-systole, while minimum neo-LVOT (and skirt neo-LVOT) area occurred most commonly in early-diastole. Subjects with LVOT obstruction (n  = 5) had smaller skirt neo-LVOT values across systole. Optimal thresholds for skirt neo-LVOT area were phase-specific (260, 210, 200, and 180 mm2 for early-systole, peak flow, mid-systole, and end-systole, respectively). Conclusion The LVOT geometry and flow rate exhibit dynamic characteristics following TMVR with LAMPOON. Subjects with LVOT obstruction had smaller skirt neo-LVOT areas across systole. The authors recommend the use of phase-specific threshold values for skirt neo-LVOT area to guide future patient selection for this procedure. LVOT EOA is a 'flow-independent' metric which has the potential to aid in characterizing LVOT obstruction severity. [ABSTRACT FROM AUTHOR]

Objective: We previously described lower leg lean mass Z-scores (LLMZ) in Fontan patients associated with worse peak oxygen consumption on metabolic exercise testing. We hypothesised that LLMZ correlates with indexed systemic flow (Qsi) and cardiac index (CI) on exercise cardiac magnetic resonance (eCMR).Methods: Thirteen patients had LLM measured by dual-energy X-ray absorptiometry within mean 40 (range 0-258) days of eCMR. LLM was converted to sex and race-specific Z-scores based on healthy reference data. Ventricular volumes and flow measurements of the ascending and descending (DAO) aorta and superior vena cava (SVC) were obtained by CMR at rest and just after supine ergometer exercise to a heart rate associated with anaerobic threshold on prior exercise test. Baseline and peak exercise measures of Qsi (SVC+DAO/BSA) and CI, as well as change in Qsi and CI with exercise, were compared with LLMZ by linear regression.Results: LLMZ was not correlated with resting flows, stroke volume or CI. There was a strong linear correlation between LLMZ and change in both CI (r=0.77, p=0.002) and Qsi (r=0.73, p=0.005) from rest to exercise. There was also a significant correlation between LLMZ and Qsi at exercise (r=0.70, p=0.008). The correlation between LLMZ and CI at exercise did not reach significance (r=0.3, p=0.07).Conclusions: In our cohort, there was a strong linear correlation between LLMZ and change in both CI and Qsi from rest to exercise, suggesting that Fontan patients with higher LLMZ may be better able to augment systemic output during exercise, improving performance. [ABSTRACT FROM AUTHOR]

Keywords: Fontan; TCPC; Computational Fluid Dynamics EN Fontan TCPC Computational Fluid Dynamics 1 2 2 02/07/23 20230101 NES 230101 Single-ventricle (SV) defects are among the most complex congenital heart defects (CHDs). TCPC haemodynamics was obtained using computational fluid dynamics (CFD) simulations that incorporate cutting-edge features, including pulsatile flow, patient-specific anatomy, and a Fontan-specific non-Newtonian rheological model [[6]]. [Extracted from the article]