Aortic Flow Research Articles

Abstract 4120856: Abdominal Aortic Blood Flow and Interstage Growth and Neurodevelopment in Patients with Single Ventricle Heart Disease

Background: Achieving normal somatic growth and neurodevelopmental (ND) milestones is a common challenge for children with single ventricle heart disease (SV) prior to stage 2 palliation (S2P). This study aimed to characterize the potential association with poor splanchnic and cerebral circulations. Methods: This retrospective single centre study included SV patients born February 1, 2012, to May 30, 2022 who underwent MRI evaluation and S2P <12 months of age. Blood flow indices, including descending aorta flow (DAoNet), were measured by phase-contrast MRI. Primary outcomes were weight-for-age Z score (WFAZ) at S2P, and 18-month ND outcomes measured by Bayley Scales of Infant and Toddler Development 3rd Ed. Spearman’s correlation was used to model associations; statistical significance was considered for p<0.05. Results: A total of 144 patients were included: 61% (n=88) male, 12% (n=17) with genetic anomalies/syndrome, median (interquartile range) gestational age was 38.7 (38, 39.6) weeks, birth weight of 3.2 (2.8-3.6) kg, and birth WFAZ -0.23 (-1.1-0.6). Stage-1 palliation (n=130) was completed at 6 (3-23) days, 34% (n=49) for hypoplastic left heart syndrome, and S2P at 6.1 (5.3-7.1) months with a WFAZ of -1.4 (-2.3- (-0.5)). S2P WFAZ did not correlate with DAoNet (Figure 1), systemic cardiac output, or other blood flow indices. Lower S2P WFAZ was associated with lower birth WFAZ, and perioperative gastrointestinal complications. Lower 18-month motor development score was associated with lower birth WFAZ, native high pulmonary blood flow physiology, and indices of increase pulmonary blood flow: superior vena cava flow (b=8.8; [95% CI: 0.7 to17], p=0.03) and pulmonary venous to systemic blood flow (Qp:Qs) (b=-7, [95% CI: -11.1 to -2.9], p=0.001). Other ND domains were associated with lower birth WFAZ, not blood flow indices. Conclusion: In SV patients, DAoNet did not correlate with growth at S2P. Modifiable factors studied were not associated with somatic growth. DAoNet, superior vena cava flow, and Qp:Qs were associated with 18-months motor development, which may indicate long-term risks of high pulmonary blood flow. Studies are needed to delineate the pathophysiology by which these findings are mediated.

Abstract 4131412: Effects of Angiotensin Converting Enzyme Inhibition And Afterload Reduction in Single Ventricle Patients Prior To Fontan: Not What You Might Think

Introduction: Pts with single ventricle (SV) after bidirectional Glenn (BDG) are placed on angiotensin converting enzyme inhibitors (ACEI) to reduce afterload, improve ventricular performance and allow for decreased systemic to pulmonary collateral flow (APC). No large scale data exists to support ACEI use in BDG pts to accomplish this. We hypothesized that ACEI may not perform as predicted. Goals: To determine if ACEI use in BDG pts decreases APC and improves ventricular function. Methods: Single center retrospective study of all BDG pts who underwent cardiac magnetic resonance (CMR) from 2010 to present. Demographics, medication, ventricular function and flow data were collected. Pts included were >1 year old and on ACEI for >3 months prior to CMR. Wilcoxon and Fisher Exact tests were used. Significance P<0.05 Results: Of the 320 BDG pts (median 2.8 years old) studied, 137 (43%) were treated with ACEI. See table for all data. There was no difference in age, sex, medications (except for ACEI) or body surface area (BSA) between both groups. APC as a % of aortic flow and APC/BSA were not different between those treated with ACEI compared to those who were not, whether right (RV) or left ventricle (LV) dominant. There was no correlation of APC with time on ACEI or ACEI dosage. Ejection fraction (EF) was lower and end-diastolic volume (EDV) was higher in BDG on ACEI for the entire group and RVs. Although LV EDV was higher with those on ACEI, LV EF was the same for those on ACEI and those who weren’t (graph). APC as a % of aortic flow and APC/BSA positively correlated with EDV (rho 0.25-0.34, P<.001). There was no difference in atrioventricular valve regurgitation between those on ACEI and those who were not (median 5 vs 6% respectively). As a surrogate for cerebral blood flow (CBF), superior vena caval (SVC) flow was lower for those on ACEI compared to those who were not. Conclusion: BDG pts treated with ACEI did not demonstrate decreased APC or improved ventricular performance. There is a suggestion that ventricular performance may be worse on ACEI. CBF is decreased in BDG on ACEI using SVC flow as a surrogate. This suggests that ACEI use in SV pts at the BDG stage is not indicated and should be discouraged.

Investigating the role of thrombosis and false lumen orbital orientation in the hemodynamics of Type B aortic dissection

While much about the fundamental mechanisms behind the initiation and progression of Type B aortic dissection (TBAD) is still unknown, predictive models based on patient-specific fluid-structure interaction (FSI) simulations can help in risk stratification and optimal clinical decision-making. Aiming at the development of personalized treatment, FSI models can be leveraged to investigate the interplay between complex aortic flow patterns and anatomical features, while considering the deformation of the arterial wall and the dissection flap. In this study, the hemodynamics of false lumen thrombosis, a large fenestration, and the orbital orientation of the false lumen is studied through image-based FSI simulations on three TBAD patient-specific geometries. A new pipeline is developed leveraging the open-source software SimVascular and ParaView to analyze multiple patients simultaneously and to achieve large-scale parallelization in FSI results based on patients’ computed tomography (CT) images. The results of this study suggest that the internal orbital orientation of the false lumen contributes to maintaining a positive luminal pressure difference ΔPTL-FL\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Delta P_{TL-FL}$$\\end{document} = PTL-PFL\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$P_{TL}-P_{FL}$$\\end{document} between the true lumen (TL) and the false lumen (FL), despite an impingement area in the false lumen near the entry tear. A positive and high luminal pressure difference is thought to promote TL expansion and FL compression. Moreover, it was also found that FL thrombosis at the entry tear region reduce the magnitude of the negative luminal pressure difference, which in turn may reduce FL expansion and the risk of unstable aortic growth. Finally, this FSI study suggests that the aortic wall and dissection flap stiffness determines the effects of a large fenestration in the descending thoracic aorta on the luminal pressure difference.

Fluid responsiveness in pediatrics: an unsolved challenge

Predicting fluid responsiveness is a major challenge in the pediatric population as vascular and pulmonary compliance differ from the adults. However it is a crucial thing to avoid the harmful fluid overload. We count on different variables to identify responders being the dynamic parameters the ones with more evidence, specially the Respiratory Variation In Aortic Blood Flow Velocity based on echocardiography. Other variables rely on the arterial waveform, like Pulse Pressure Variation or Stroke Volume Variation seem to have limitations but new tests like VTC are arriving to overcome their drawbacks. We review the actual evidence regarding fluid responsiveness prediction in children and the anatomic and physiologic peculiarities of children that explain why they do not respond like adults and why we should study them in particular.

Ventriculo-arterial coupling parameters by cardiac magnetic imaging are associated with outcome in patients with a systemic right ventricle

Abstract Introduction Invasive studies have shown that patients with a systemic right ventricle (sRV) due to congenitally corrected transposition of the great arteries (TGA) or complete TGA after atrial switch procedure possess impaired ventriculo-arterial coupling (VAC) parameters. The randomized, placebo-controlled, double-blinded, multi-centre SERVE trial investigated the effect of phosphodiesterase-5 inhibitor tadalafil in sRV patients on RV endsystolic volume (RVESV), with negative results. Aim of this sub-analysis was to evaluate changes of non-invasively assessed VAC parameters over time and for treatment effect. We prospectively analysed whether VAC parameters predict clinical outcome in sRV patients. Methods Volumetric RV parameters and aortic flow were assessed by cardiac magnetic resonance (CMR) and analysed (blinded for patient and assessment time and treatment) at baseline, after 3 years, or after 1 year if the study drug was withdrawed. Parameters were compared with clinical outcome at each visit. Effective arterial elastance Ea was calculated as RV endsystolic pressure (RVesp) / aortic forward flow, with RVesp defined as 0.9 x systolic blood pressure. Right ventricular endsystolic elastance Ees was calculated by RVesp / RVESV, and RV VA-coupling ratio was expressed as Ea/Ees. Treatment effect was analysed using ANCOVA with baseline values and FU-time as covariates. Values of > 4th quartile were used as cut-off for Kaplan-Meier analysis on the primary outcome, defined as a composite of all-cause death, clinically relevant arrhythmias and hospitalisation for heart failure. Results CMR exams were available for 78 patients at baseline (40±11 years, 33% females) and for 71 patients at follow-up (FU). No effect of tadalafil compared to placebo was evident for effective arterial elastance Ea (p=0.35), ventricular endsystolic elastance Ees (p=0.11), VAC Ea/Ees (p=0.82), RVESVi (p=0.63) and RV ejection fraction (RVEF, p=0.6). Over the 3 years FU-time, Ea (p=0.24) and RVEF (p=0.11) did not change, whereas Ees mildly decreased (p=0.0052, fig. 1 A) and Ea/Ees increased (p=0.013, fig. 1 B). During FU, 14 patients experienced a clinical event. An Ees <0.73 mmHg/ml and an Ea/Ees ratio of >1.94 were associated with adverse clinical outcomes (for both p=0.004, fig. 2). Conclusion In sRV patients, treatment with tadalafil had no effect on VAC parameters compared to placebo. CMR-derived ventricular endsystolic elastance (Ees) and Ea/Ees ratio changed over the FU of 3 years and were associated with adverse clinical outcome.Figure 1Figure 2

Worse arterial pressure reservoir capacity is associated with exacerbated hemodynamic response to capnogram changes and more labile intraoperative cardiopulmonary-metabolic coupling

Abstract Background The apparent promise of capnography as a cardiac monitor based on the coupled cardiopulmonary response to metabolic changes remains hampered by inconsistent results in studies investigating previous correlations between hemodynamics (e.g.cardiac output) and end-tidal CO2 (EtCO2).(1,2,3) Excess pressure (Pexcess), a dynamic sub-component of pressure waveform representing pressure beyond buffering capacity (reservoir pressure) of elastic large arteries, strongly correlates with aortic flow in humans, suggesting the Pexcess as a promising tool for non-invasive hemodynamic monitoring.(4,5) Purpose We aimed to clarify potential cofounders and pathophysiological mechanisms modifying the EtCO2-arterial hemodynamic coupling, by analysing the intra-operative temporal relations of paired reservoir-excess and capnogram parameters Methods In 190 patients with normal pre-operative pulmonary function tests who underwent non-cardiac surgery, simultaneous capnogram and intra-arterial pressure signals were analysed off-line. Signal windows (>2 minutes) of maximum and minimum mean arterial pressure were autoidentified, the capnogram and pressure signals were averaged into a single representative cycle, to extract reservoir-excess pressure and capnogram parameters (EtCO2, expiratory slope, alpha slope, and plateau slope) accordingly.(6,7) Arterial reservoir capacity (ARC) was defined as Preservoir/Pexcess, which was used to stratify patients into quartiles. Relationships between maximum changes in capnogram and pressure parameters were analysed (Figure 1). Results The ΔEtCO2 and ΔPa mean were correlated significantly in all groups. In patients with the highest ARC (Q4), Pexcess remained unaltered in response to ΔEtCO2 (r:0.095 p:0.545), unlike other subgroups with significant positive correlations. In Q4 (the highest ARC group), the increment in Preservoir was the main cause of ΔPa in relation to ΔEtCO2. In contrast, the ΔEtCO2 - ∆Pexcess relationship was most pronounced in the group with the poorest ARC (r:0.634 p:0.005), underlying the significance of the pressure reservoir behaviour as a determinant of metabolic oscillations in arterial hemodynamics, even though the changes in ΔEtCO2 were equivalent.(Figure 2) Conclusion(s) Worse arterial pressure reserve capacity is associated with an exacerbated hemodynamic response to capnogram changes and a more labile cardiopulmonary-metabolic coupling, characterised by a pronounced increase in excess pressure in response to increased EtCO2 in patients with low ARC. Substantial Pa alterations accompanying EtCO2 changes had opposite drivers in low and high ARC groups (predominant augmentation of Preservoir vs Pexcess). Utilisation of the capnogram for cardiac hemodynamic monitoring is substantially affected by ARC, hence it should be considered while developing capnogram-based monitoring indices.Figure 1.Methodology and example casesFigure 2.Main results

Good agreement between cardiac magnetic imaging protocols using free-breathing and breath-holding techniques for flow quantification in valvular heart disease

Abstract Background Cardiac magnetic resonance (CMR) evaluation of valvular heart disease is an important diagnostic tool when echocardiography is inconclusive. Flow quantification is usually performed during breath hold, which can be challenging in valvular heart disease patients often suffering from dyspnea and heart failure. Purpose The purpose of the present study is to evaluate a free-breathing protocol of flow measurement in the aortic, pulmonary and tricuspid valves in healthy subjects (HS) and patients with tricuspid regurgitation (TR). Methods Phase contrast flow volume measurements were performed in 20 HS and 25 patients with TR using standard breath-holding (BH) and a free-breathing (FB) technique. Two venc-adjusted volume acquisition were acquired in the aortic, pulmonary and tricuspid valve during BH and one during FB. Mean, standard deviation (SD) and limits of agreement (LoA) for aortic forward flow volume (AoFF), pulmonary forward flow volume (PuFF) and tricuspid inflow volume (TrIF) were evaluated. Results Figure 1 presents flow volume (ml) of AoFF, PuFF and TrIF during BH (mean of 2 measurements) and FB. Conclusions The present study demonstrated good agreements between phase contrast flow measurements using FB and BH techniques. These parameters are used in the evaluation of aortic, mitral, pulmonary and tricuspid regurgitations using CMR imaging. Thus, free-breathing CMR acquisition can be an important complement in the assessment of valvular heart disease and may be applied in patients with difficulty to hold their breath.

Transcatheter aortic valve replacement and the value of increasing treatment for severe symptomatic aortic stenosis: a plain language summary

Plain Language Summary What is this summary about? This article summarizes an economic evaluation of transcatheter aortic valve replacement (TAVR), a treatment for severe symptomatic aortic stenosis (SSAS). SSAS occurs when the aortic valve, which allows blood to leave the heart, becomes very narrow. This reduces blood flow to the body, causing symptoms like tiredness, chest pain, dizziness, or fainting. Treating SSAS requires replacing the valve. Untreated SSAS results in heart failure and death. Before TAVR, SSAS patients had two options, medical management and surgical aortic valve replacement (SAVR). Medical management helps with symptoms but does not replace the valve, leading patients to eventually die from SSAS. SAVR replaces the valve through open-heart surgery, which is invasive, involving making a large cut through the chest bone. Concerns about this invasiveness led many patients to avoid SAVR, leaving their SSAS untreated. TAVR was introduced in 2010. It is less invasive than SAVR, involving inserting a new valve through a small cut in the leg. TAVR has become popular and twice as many patients now undergo TAVR compared to SAVR. We measure TAVR’s net benefits as the value of its health benefits minus its healthcare costs. We measure these net benefits in three patient groups aged 65 and above in the United States. Group 1 patients are ineligible for SAVR, so TAVR is their only treatment option. Group 2 patients would have received SAVR if TAVR were not available. Group 3 patients are eligible for SAVR but concerned about its invasiveness, and so would have stayed untreated without TAVR. Economic evaluation: A type of study that measures the benefits and costs of a treatment like TAVR and judges whether the benefits are sufficiently large to justify the costs (or put another way, whether the technology represents good value-for-money). Transcatheter aortic valve replacement (TAVR): Replacement of the aortic valve in SSAS patients using a thin tube called a catheter that enters the body through a small cut near the leg and delivers and installs a valve replacement. New treatment option for SSAS from 2010 onwards. A minimally invasive treatment. Aortic stenosis (AS): A heart condition where a heart valve called the aortic valve becomes very narrow, forcing the heart to work harder and limiting blood flow to the rest of the body. Severe Symptomatic Aortic Stenosis (SSAS): Severe form of AS when the narrowing of the aortic valve is significant and accompanied by symptoms like fatigue, chest pain, shortness of breath, dizziness, or fainting. What were the key takeaways? Net benefits per patient are significant in all groups, roughly equal in groups 1 and 2, and over six times larger in group 3. When net benefits are added up across patients, group 3’s total net benefit is 30 times larger than that of groups 1 and 2 combined. What are the main conclusions? Past studies ignored TAVR’s value in helping treat patients who might go untreated because of concerns over SAVR’s invasiveness. But this is TAVR’s largest value to SSAS patients. Our findings support continuing and increasing access to TAVR among SSAS patients, especially those who may go untreated because of concerns about invasive treatment. Aortic valve: One of the four heart valves. It connects the left side of the heart with the aorta, which is the large artery carrying oxygen-rich blood to the body. The aortic valve controls blood flow into the aorta, ensuring it moves in one direction. Medical management (MM): Involves medication and monitoring of SSAS patients but no treatment in the form of valve replacement. Associated with high risk of death. Surgical aortic valve replacement (SAVR): Replacement of the aortic valve in SSAS patients through open heart surgery. The sole treatment option for SSAS before 2010. A highly invasive treatment given its use of open-heart surgery. This is an abstract of the Plain Language Summary of Publication article. View the full Plain Language Summary PDF of this article to read the full-text Link to original article here

Evaluating fetal pulmonary vascular development in congenital heart disease: a comparative study using the McGoon index and multiple parameters of fetal echocardiography.

The purpose of this study was to evaluate the value of MGI and multi-parameter in the assessment of different pulmonary circulation blood volumes in congenital heart disease. This study included 350 fetuses categorized into two groups: Normal group consisted of 258 fetuses with no discernible abnormalities through echocardiography as control Group A; Abnormal group with abnormal echocardiogram, including Group B of 71 fetuses with decreased pulmonary blood flow or pulmonary atresia and Group C of 21 fetuses with reduced or detached aortic blood flow. The MGI and Z-scores were measured and compared among these groups. Significant variations were noted in the aortic outflow Z-scores (AO-Zs) (p<0.01), pulmonary artery (PA) (p<0.01), PA Z-scores (PA-Zs) (p<0.01), PA/AO (p<0.01), right PA (p<0.01), and MGI (p<0.01) among the three groups (all p<0.05). Among fetuses with decreased pulmonary blood flow or pulmonary atresia, PA, PA-Zs, and MGI in fetuses with reverse DA flow perfusion were lower than those in the DA forward perfusion group. Fetal echocardiography, incorporating the MGI and multi-parameter, not only allows for the evaluation of pulmonary blood flow and pulmonary vascular development of the fetus but also enables the observation of changes in pulmonary blood flow and MGI development across different gestational weeks.

Malignant arterial hypertension in a child with nonspecific aortoarteritis

The article presents a clinical case of malignant renovascular hypertension in a child, resulting from non-specific aortoarteritis. The disease initially manifested with abdominal pain and convulsions, leading to hospitalization. During the hospital stay, blood pressure readings were elevated to 180/100 mmHg and higher. Over the course of a year, the patient underwent pathogenetic (immunosuppressive), combined (triple) antihypertensive treatment, and symptomatic therapy. Due to the malignant nature of the hypertension, progression of organ damage, a high risk of complications and mortality, and the ineffectiveness of conservative treatment, surgical interventions were performed. The first stage involved polyposition abdominal aortography and stent-graft implantation in the abdominal aorta. Despite restored blood flow in the abdominal aorta, blood pressure remained elevated over the following three months, even with ongoing antihypertensive therapy. As a result, a nephrectomy was performed at the second stage. Postoperatively, the patient’s blood pressure significantly decreased to 130/90–120/80 mmHg. Antihypertensive therapy was continued to reach lower target blood pressure values. Non-specific aortoarteritis remains a prognostically unfavorable condition, even after reconstructive surgery, owning to its autoimmune nature, which suggests ongoing arterial inflammation even during clinical remission. This necessitates lifelong monitoring by a rheumatologist.

First diagnosis of severe coarctation of the aorta necessitation percutaneous intervention during pregnancy, a case report

Abstract Background Coarctation of the aorta (CoA) is a common congenital heart defect that affects about 3-4 in every 10,000 live births. Despite clear signs on clinical examination, the diagnosis is sometimes not made until adulthood. An increasing number of patients with CoA are reaching child-bearing age. Unrepaired CoA or severe recurrent stenosis during pregnancy is a significant concern, as it poses a high risk of maternal and foetal complications and even death. Case summary A 21-year-old women was referred to the cardiology department at 17 weeks’ gestation for management of arterial hypertension and unexplained systolic murmur. She had been diagnosed with hypertension elsewhere the year before presentation, but unfortunately this remained unexplored. She had been started on labetalol early in the pregnancy. Clinical examination showed a loud systolic heart murmur extending from parasternal to subclavicular and scapular areas. Pulses in the lower extremities were very weak and blood pressure was slightly elevated with a significant gradient between the upper and lower extremities. Echocardiography showed remarkable absence of pulsatile flow in the abdominal aorta and narrowing just distal to the subclavian artery with typical diastolic tail pattern on suprasternal imaging. Cardiac magnetic resonance confirmed the presence of a severe coarctation distal to the subclavian artery and presence of multiple collaterals allocating this patient in the extremely high-risk category with a risk of up to up 40-100% of maternal cardiac event during pregnancy. An extensive multidisciplinary team meeting was convened. After initial medical optimisation, increased claudication and signs of placental hypoperfusion necessitated an endovascular procedure under general anaesthesia at 23 weeks’ gestation. A Bentley BeGraft Plus stent (16x38 mm) was successfully placed. Postoperative ultrasound showed biphasic placental perfusion and normalisation of blood pressure and ankle-brachial indices. At 36 weeks’ gestation, the patient gave birth to a healthy child. Conclusion CoA should be considered in any young patient with arterial hypertension. Altered maternal haemodynamics during pregnancy resulted in severe symptomatic CoA and reduced placental flow necessitating percutaneous intervention during pregnancy. A multidisciplinary pregnancy heart team is essential for optimal treatment management in these high-risk patients.

Using an Isolated Working Rat Heart Model to Test Donor Heart Preservation Strategies.

Optimization of donor heart preservation solutions has played a key role in reducing ischemia-reperfusion injury in donor hearts during organ retrieval, transportation, and transplantation. Previous work from our laboratory showed that the addition of glyceryl trinitrate and erythropoietin to donor heart preservation solutions could significantly improve cardiac functional recovery after prolonged cold storage and in donation after circulatory death hearts. This supplementation protocol has been implemented in clinical use in transplant units around Australia, Belgium, and the United Kingdom. Here, we outline a protocol for testing supplementation strategies using an ex vivo isolated working rat heart (IWRH) perfusion circuit. Using this methodology, supplementation strategies can be tested in the context of prolonged cold static storage, donation after brain death, and donation after circulatory death donor heart preservation. Cardiac functional recovery, measured by aortic flow, coronary flow, cardiac output, pulse pressure, and heart rate, can be used to determine whether a particular preservation strategy can minimize ischemia-reperfusion injury of the donor heart.

Automated Quantification of Simple and Complex Aortic Flow Using 2D Phase Contrast MRI

(1) Background and Objectives: Flow assessment using cardiovascular magnetic resonance (CMR) provides important implications in determining physiologic parameters and clinically important markers. However, post-processing of CMR images remains labor- and time-intensive. This study aims to assess the validity and repeatability of fully automated segmentation of phase contrast velocity-encoded aortic root plane. (2) Materials and Methods: Aortic root images from 125 patients are segmented by artificial intelligence (AI), developed using convolutional neural networks and trained with a multicentre cohort of 160 subjects. Derived simple flow indices (forward and backward flow, systolic flow and velocity) and complex indices (aortic maximum area, systolic flow reversal ratio, flow displacement, and its angle change) were compared with those derived from manual contours. (3) Results: AI-derived simple flow indices yielded excellent repeatability compared to human segmentation (p &lt; 0.001), with an insignificant level of bias. Complex flow indices feature good to excellent repeatability (p &lt; 0.001), with insignificant levels of bias except flow displacement angle change and systolic retrograde flow yielding significant levels of bias (p &lt; 0.001 and p &lt; 0.05, respectively). (4) Conclusions: Automated flow quantification using aortic root images is comparable to human segmentation and has good to excellent repeatability. However, flow helicity and systolic retrograde flow are associated with a significant level of bias. Overall, all parameters show clinical repeatability.

The value of blood flow velocity and pressure gradient in differentiating patients with different types of heart failure.

Patients with different types of heart failure (HF) exhibit varying rates of blood flow through cardiac chambers and pressure gradients across the aortic valve, attributed to differing degrees of myocardial contractility. Assessment of these dynamics offers insights into early HF diagnosis. This study aimed to analyze left ventricular outflow tract (LVOT) blood flow parameters, specifically peak blood flow velocity and pressure gradient derived from four-dimensional flow cardiovascular magnetic resonance (4D flow CMR), and to evaluate 4D flow CMR's utility in distinguishing HF types. This prospective cross-sectional study recruited 115 HF patients from January 2019 to May 2022 at the General Hospital of Ningxia Medical University, classified by the New York Heart Association Cardiac Function Classification of Heart Failure as class II-IV, alongside a control group (n=30). Participants underwent cardiovascular magnetic resonance (CMR), including 4D flow. HF patients were categorized into heart failure with reduced ejection fraction (HFrEF, n=55), heart failure with mildly reduced ejection fraction (HFmrEF, n=30), and heart failure with preserved ejection fraction (HFpEF, n=30), based on ejection fraction. The cardiac functional parameters and aortic valve flow indices were measured using Circle Cardiovascular Imaging. LVOT 4D flow data were obtained 3 mm below the junction of the aortic valve leaflets, assessing peak velocities above and below the valve. Differences in cardiac function and blood flow parameters between groups were analyzed using one-way analysis of variance (ANOVA). The accuracy of these parameters in identifying subgroups was assessed using the receiver operating characteristic (ROC) curve. Analysis of conventional cardiac function parameters revealed that left ventricular ejection fraction (LVEF) was significantly lower in the HFrEF and HFmrEF groups compared to the HFpEF and control groups (P<0.01). Additionally, end-diastolic volume and end-systolic volume were significantly higher in the HFrEF and HFmrEF groups than in the HFpEF and control groups (P<0.01). However, there were no significant differences in cardiac function parameters between the HFpEF and control groups (P>0.05). Significant differences were observed in aortic valve peak pressure gradients (Supra-APGmax) among the four study groups (5.01±1.09 vs. 6.23±2.94 vs. 7.63±1.81 vs. 8.89±2.97 mmHg, P<0.05). Aortic valve peak velocities in the HFrEF group differed significantly from the HFpEF and control groups (111.31±12.05 cm/s vs. 137.2±16 vs. 147.15±24.55 cm/s, P<0.001). The ROC curve for the pressure gradient below the aortic valve had an area under the curve (AUC) of 0.728 [95% confidence interval (CI): 0.591-0.864, P=0.002], with an optimal threshold of 4.72 mmHg (sensitivity: 0.8, specificity: 0.7, Youden index: 0.5). HF patients exhibit reduced pressure gradients across the aortic valve during systole, indicative of altered intracardiac blood flow dynamics. Combining aortic valve velocities and pressure gradients can aid in distinguishing different types of HF, including HFpEF patients.

Endothelial YAP/TAZ activation promotes atherosclerosis in a mouse model of Hutchinson-Gilford progeria syndrome.

Hutchinson-Gilford progeria syndrome (HGPS) is an extremely rare disease caused by the expression of progerin, an aberrant protein produced by a point mutation in the LMNA gene. HGPS patients show accelerated aging and die prematurely mainly from complications of atherosclerosis such as myocardial infarction, heart failure, or stroke. However, the mechanisms underlying HGPS vascular pathology remain ill defined. We used single-cell RNA sequencing to characterize the aorta in progerin-expressing LmnaG609G/G609G mice and wild-type controls, with a special focus on endothelial cells (ECs). HGPS ECs showed gene expression changes associated with extracellular matrix alterations, increased leukocyte extravasation, and activation of the yes-associated protein 1/transcriptional activator with PDZ-binding domain (YAP/TAZ) mechanosensing pathway, all validated by different techniques. Atomic force microscopy experiments demonstrated stiffer subendothelial extracellular matrix in progeroid aortas, and ultrasound assessment of live HGPS mice revealed disturbed aortic blood flow, both key inducers of the YAP/TAZ pathway in ECs. YAP/TAZ inhibition with verteporfin reduced leukocyte accumulation in the aortic intimal layer and decreased atherosclerosis burden in progeroid mice. Our findings identify endothelial YAP/TAZ signaling as a key mechanism of HGPS vascular disease and open a new avenue for the development of YAP/TAZ targeting drugs to ameliorate progerin-induced atherosclerosis.

Impact of peripheral venoarterial extracorporeal membrane oxygenation support for heart failure on systemic hemodynamics and aortic blood flow

Peripheral venoarterial extracorporeal membrane oxygenation (VA-ECMO) is an advanced temporary life support system for patients with refractory cardiogenic shock or severe cardiopulmonary failure. However, the reperfusion of oxygenated blood into the arterial system via a peripheral artery will induce substantial hemodynamic changes that might contribute to the development of complications. In this study, we developed two types of computational models to quantify the hemodynamic changes induced by the peripheral VA-ECMO support for systolic heart failure (HF) of various severities. One was a lumped-parameter model used for exploring the optimal workload of extracorporeal membrane oxygenation (ECMO) for a specific severity of HF, whereas the other one was a geometrical multiscale model capable of simulating the detailed flow field in the aorta while accounting for the hemodynamic coupling of VA-ECMO with the cardiovascular system. Numerical results revealed that the retrograde transmission of ECMO-supplied blood flow toward the heart not only considerably inhibited cardiac output but also induced marked flow disturbance and regionally high or oscillatory wall shear stress (WSS) in the aorta that may increase the risk of thrombosis and vascular dysfunction. The major characteristics of flow disturbance and spatial distribution of abnormal WSS were codetermined by the cardiac function and workload of ECMO while less influenced by the morphology of aorta. These findings emphasized the importance of tuning the workload of ECMO based on patient-specific cardiac function to balance the amount of blood oxygenation support by ECMO against the risk of complications associated with hemodynamic abnormalities.

Design Improvement for Interventional Blood Pumps Based on Flow Analysis

Abstract Interventional blood pumps serve as a crucial component for temporary mechanical circulatory support in the treatment of heart failure, specifically designed to improve blood circulation recovery and survival rate in patients undergoing treatment for acute cardiovascular diseases. This study aims to design a novel interventional blood pump with a focus on achieving exceptional hydraulic performance and superior blood compatibility based on numerical simulation, which considers the interactions between the blood pump and the upstream (drainage cannula) and downstream (aorta) flow fields, establishing a full-scale flow field analysis. For the numerical method, the Reynolds-Averaged Navier-Stokes (RANS) equations coupling with the k-ɛ turbulence model are solved. The result indicates that high shear stress exists around the leading and trailing edges of impeller blades and there is a jet at the outlet of impeller, and the blade leading and trailing edge, and the outlet of the impeller are the dominant regions for higher hemolysis occurrence. It is also noted that the presence of an interventional blood pump generates significant vortex structures within the aorta. To effectively reduce the hemolysis index, back-sweep concept is applied to this study also optimize the impeller’s leading edge. The analysis result confirms that the back swept leading edge of impeller blade helps improve the blood compatibility for interventional blood pumps.

Characterization and Z-score Calculation of Cardiac MRI parameters in patients after the Fontan operation. A Fontan Outcome Registry using CMR Examinations (FORCE) study

BackgroundCardiac magnetic resonance (CMR) offers valuable hemodynamic insights post-Fontan, but is limited by the absence of normative single ventricle data. The Fontan Outcomes Registry using CMR Examinations (FORCE) is a large international Fontan-specific CMR registry. This study used FORCE registry data to evaluate expected CMR ventricular size/function and create Fontan-specific z-scores adjusting for ventricular morphology (VM) in healthier Fontan patients. Methods“Healthier” Fontan patients were defined as patients free of adverse outcomes, who are New York Heart Association Class I, have mild or less valve disease, and <30% aortopulmonary collateral burden. General linear modeling was performed on 70% of the dataset to create z-scores for volumes and function. Models were tested using the remainder (30%) of the data. The z-scores were compared between children and adults. The z-scores were also compared between “healthier” Fontan and patients with adverse outcomes (death, listing for transplantation or multiorgan disease). ResultsThe “healthier” Fontan population included 885 patients (15.0 ± 7.6 years) from 18 institutions with 1,156 CMR examinations. Patients with left ventricle morphology had lower volume, mass and higher ejection fraction (EF) compared to right or mixed (two-ventricles) morphology (p<0.001 for all pairwise comparisons). Gender, BSA and VM were used in z-scores. Of the “healthier” Fontan patients, 647 were children <18 years and 238 were adults. Adults had lower ascending aorta flow (2.9 ± 0.7 vs 3.3 ± 0.8L/min/m2, p<0.001) and ascending aorta flow z-scores (-0.16 ± 1.23 vs 0.05 ± 0.95, 0.02) compared to children. Additionally, there were 1595 patients with adverse outcomes who were older (16.1 ± 9.3 vs 15.0 ± 7.6, p<0.001) and less likely to have LV morphology (35 vs 47%, p<0.001). Patients with adverse outcomes had higher z-scores for ventricular volume and mass and lower z-scores for EF and ascending aorta flow compared to the “healthier” Fontan cohort. ConclusionThis is the first study to generate CMR z-scores post-Fontan. Importantly the z-scores were generated and tested in “healthier” Fontan patients and both pediatric and adult Fontan patients. These equations may improve CMR-based risk stratification after the Fontan operation.

Physiological control for left ventricular assist devices based on deep reinforcement learning.

The improvement of controllers of left ventricular assist device (LVAD) technology supporting heart failure (HF) patients has enormous impact, given the high prevalence and mortality of HF in the population. The use of reinforcement learning for control applications in LVAD remains minimally explored. This work introduces a preload-based deep reinforcement learning control for LVAD based on the proximal policy optimization algorithm. The deep reinforcement learning control is built upon data derived from a deterministic high-fidelity cardiorespiratory simulator exposed to variations of total blood volume, heart rate, systemic vascular resistance, pulmonary vascular resistance, right ventricular end-systolic elastance, and left ventricular end-systolic elastance, to replicate realistic inter- and intra-patient variability of patients with a severe HF supported by LVAD. The deep reinforcement learning control obtained in this work is trained to avoid ventricular suction and allow aortic valve opening by using left ventricular pressure signals: end-diastolic pressure, maximum pressure in the left ventricle (LV), and maximum pressure in the aorta. The results show controller obtained in this work, compared to the constant speed LVAD alternative, assures a more stable end-diastolic volume (EDV), with a standard deviation of 5 mL and 9 mL, respectively, and a higher degree of aortic flow, with an average flow of 1.1 L/min and 0.9 L/min, respectively. This work implements a deep reinforcement learning controller in a high-fidelity cardiorespiratory simulator, resulting in increases of flow through the aortic valve and increases of EDV stability, when compared to a constant speed LVAD strategy.

Aortic isthmus flow reversal in fetal coarctation of the aorta and the associated factors.

The aim of this study was to investigate the presence of aortic isthmus flow reversal and its associated factors in fetuses with positive and false-positive coarctation of the aorta (CoA) compared with normal controls. Pregnant women with fetuses suspected of CoA and normal control were enrolled, and these women experienced prenatal ultrasound scan and followed up for 6 months after birth to confirm the presence of CoA. All the ultrasound parameters were analyzed. A total of 134 pregnant women were enrolled, with 43 CoA-positive fetuses and 91 CoA false-positive fetuses, and 334 matched pregnant women were enrolled in the control group. Aortic isthmus flow reversal occurred in 28 (65.1%) fetuses in the CoA-positive group, significantly (p < 0.05) more than in the false-positive (37 or 40.7%) or control group (64 or 19.2%). Aortic isthmus flow reversal was mostly in the full systole (n = 17 or 60.7%) or late systole and early-middle diastole (n = 10 or 35.7%) in the CoA-positive fetuses (n = 27 or 96.4%), significantly (p < 0.001) different from that in the false-positive or control group. The aortic isthmus flow reversal peak systolic velocity (PSV), flow volume, and ratio of reversed flow/forward flow were significantly (p < 0.05) increased in the CoA-positive and false-positive groups than in the control group. The aortic isthmus flow reversal incidence was significantly (p < 0.05) correlated with the middle cerebral artery (MCA) PSV in the total three groups or in the false-positive group but was significantly (p < 0001) negatively correlated with the MCA resistance index (RI) in the CoA-positive group. The incidence of the aortic isthmus flow reversal was significantly (p < 0.05) positively correlated with the umbilical artery (UA) RI in the false-positive group and with the UA RI in the total three groups. Independently associated factors for aortic isthmus flow reversal were isthmic flow volume/CCO (combined cardiac output) in the CoA-positive group. Reversal of flow in the aortic isthmus is much more common in true-positive cases of CoA as compared to controls, and isthmic flow reversal in the full systolic phase only suggests presence of CoA. The aortic isthmic reversed flow volume accounts for over half of the isthmic forward flow volume in the CoA-positive fetuses than in the normal controls.