4D Flow Cardiac Magnetic Resonance Research Articles

Feasibility of 4D Flow Cardiac Magnetic Resonance Imaging for Imaging Surveillance After LAAO

Feasibility of 4D Flow Cardiac Magnetic Resonance Imaging for Imaging Surveillance After LAAO

Accurate quantification of pulmonary perfusion ratio in children with congenital heart disease using partial volume corrected 4D flow cardiac magnetic resonance.

In children with congenital heart disease (CHD), lung scintigraphy is the reference standard for evaluation of pulmonary perfusion. 4D flow CMR offers a non-ionizing alternative. Due to the intrinsic limitation in the spatial resolution, however, 4D flow may display clinically unacceptable differences compared to the reference standard. This case study aims to highlight the importance of correcting for such partial volume errors to accurately evaluate pulmonary perfusion in small pulmonary arteries. Children with CHD, mainly those with transposition of the great arteries or tetralogy-of-Fallot, referred to CMR from 2020 to 2022 at our clinic, were retrospectively reviewed; n = 37. All patients had been examined with a free breathing, motion-corrected 4D flow protocol. Comparison in pulmonary perfusion (PPR: relative flow through right and left pulmonary arteries) with scintigraphy were performed both for 4D flow before and after partial volume correction. Patients with large pulmonary arteries, 76%, displayed small differences in PPR between modalities (<20%), while patients with arteries of only a few pixels, 24%, displayed differences up to 178%, depending on the relative difference in size between the right and left pulmonary artery. Differences were effectively reduced after partial volume correction (<21%). The present report shows that 4D flow is a promising tool to accurately evaluate the pulmonary perfusion in children with CHD, but that partial volume correction is warranted to overcome its limitation in the spatial resolution. Without such correction, lung scintigraphy is still recommended to ensure high diagnostic certainty in children with small pulmonary arteries.

Impact of 4D-Flow CMR Parameters on Functional Evaluation of Fontan Circulation.

We sought to evaluate the potential clinical role of 4D-flow cardiac magnetic resonance (CMR)-derived energetics and flow parameters in a cohort of patients' post-Fontan palliation. In patients with Fontan circulation who underwent 4D-Flow CMR, streamlines distribution was evaluated, as well a 4D-flow CMR-derived energetics parameters as kinetic energy (KE) and energy loss (EL) normalized by volume. EL/KE index as a marker of flow efficiency was also calculated. Cardiopulmonary exercise test (CPET) was also performed in a subgroup of patients. The population study included 55 patients (mean age 22±11 years). The analysis of the streamlines revealed a preferential distribution of the right superior vena cava flow for the right pulmonary artery (62.5±35.4%) and a mild preferential flow for the left pulmonary artery (52.3±40.6%) of the inferior vena cave-pulmonary arteries (IVC-PA) conduit. Patients with heart failure (HF) presented lower IVC/PA-conduit flow (0.75±0.5 vs 1.3±0.5 l/min/m2, p=0.004) and a higher mean flow-jet angle of the IVC-PA conduit (39.2±22.8 vs 15.2±8.9, p<0.001) than the remaining patients. EL/KE index correlates inversely with VO2/kg/min: R: -0.45, p=0.01 peak, minute ventilation (VE) R: -0.466, p<0.01, maximal voluntary ventilation: R:0.44, p=0.001 and positively with the physiological dead space to the tidal volume ratio (VD/VT) peak: R: 0.58, p<0.01. From our data, lower blood flow in IVC/PA conduit and eccentric flow was associated with HF whereas higher EL/KE index was associated with reduced functional capacity and impaired lung function. Larger studies are needed to confirm our results and to further improve the prognostic role of the 4D-Flow CMR in this challenging population.

Assessment of paravalvular regurgitation after transcatheter aortic valve replacement using 2D multi-venc and 4D flow CMR.

To compare the novel 2D multi-venc and 4D flow acquisitions with the standard 2D flow acquisition for the assessment of paravalvular regurgitation (PVR) after TAVR using cardiac magnetic resonance (CMR)-derived regurgitant fraction (RF). In this prospective study, patients underwent CMR one month after TAVR to assess PVR using 2D multi-venc and 4D flow, in addition to standard 2D flow. Scatterplots and Bland-Altman plots were used to assess correlation and visualize agreement between techniques. Reproducibility of measurements was assessed with intraclass correlation coefficients. The study included 21 patients (mean age, 80 years ± 5 [SD], 9 men). Mean RF was 11.7 ± 10.0% using standard 2D flow, 10.6 ± 7.0% using 2D multi-venc flow, and 9.6 ± 7.3% using 4D flow. There was a very strong correlation between the RFs assessed with 2D multi-venc and standard 2D flow (r = 0.88, p < 0.001), and a strong correlation between the RFs assessed with 4D flow and standard 2D flow (r = 0.74, p < 0.001). Bland-Altman plots revealed no significant bias between the RFs (2D multi-venc: 1.3%; 4D flow: 0.3%). Intra- and interobserver reproducibility for 2D multi-venc flow were 0.98 and 0.97, respectively; and 0.92 and 0.90 for 4D flow, respectively. 2D multi-venc and 4D flow produce accurate quantification of PVR after TAVR. The fast acquisition of the 2D multi-venc sequence, and the free-breathing acquisition with retrospective plane selection of the 4D flow sequence provide useful advantages in clinical practice, especially in the frail TAVR population.

Kiosk 2R-TC-10 - Detection of Previously Undiagnosed Partial Anomalous Pulmonary Venous Return via 4D Flow Cardiac Magnetic Resonance Imaging in Patients with Turner Syndrome

Kiosk 2R-TC-10 - Detection of Previously Undiagnosed Partial Anomalous Pulmonary Venous Return via 4D Flow Cardiac Magnetic Resonance Imaging in Patients with Turner Syndrome

Kiosk 9Q-TA-01 - 4D Flow Cardiac Magnetic Resonance for Hemodynamic Assessment of Alcohol Septal Ablation for Hypertrophic Obstructive Cardiomyopathy with Multiple Obstructions

Kiosk 9Q-TA-01 - 4D Flow Cardiac Magnetic Resonance for Hemodynamic Assessment of Alcohol Septal Ablation for Hypertrophic Obstructive Cardiomyopathy with Multiple Obstructions

Hemodynamic forces from 4D flow magnetic resonance imaging for optimised prediction of cardiac resynchronisation therapy outcome

Abstract Background Patients with heart failure and left bundle branch block (LBBB) may receive cardiac resynchronisation therapy (CRT), but many patients have limited treatment response (1). The use of imaging to optimise patient selection has been repeatedly attempted with some success (2), and scar detected on late gadolinium enhancement (LGE) imaging has been associated with reduced response rates (3). Intraventricular hemodynamic force (HDF) analysis has been suggested as a novel marker for assessment of patients eligible for CRT (4). The aim of this study was therefore to investigate if septal scar from LGE or left ventricular HDF computed from cardiac magnetic resonance (CMR) imaging can improve prediction of CRT outcome. Methods Patients with heart failure, EF&amp;lt;35% and LBBB (n=22) underwent CMR with 4D flow at 1.5T or 3T (Achieva, Philips Healthcare) prior to CRT (Figure 1). Scar was assessed by LGE. Left ventricular HDF were computed based on the Navier-Stokes equations, using a validated module in the software Segment v3.3 R10057 (Medviso, Lund, Sweden) (5). Forces (N) were analysed in three orthogonal directions as root mean square (RMS) and peak values, reported in median [interquartile range]. Transversal/longitudinal HDF ratio was calculated for systole and diastole. Echocardiography was performed before and six months after CRT, and patients with end-systolic volume reduction ≥15% at follow-up were defined as responders. The Mann-Whitney U test was used for group comparisons, Fisher’s exact test for binary categorical data, Wilcoxon test for paired comparisons, and receiver operating characteristic analysis for prediction of CRT response. Results There was no difference between responders and non-responders in LGE (Table 1). Non-responders had smaller HDF than responders in the inferior-anterior direction in systole (RMS: 0.055 [0.027] vs 0.070 [0.032], p=0.04; peak: 0.11 [0.069] vs 0.15 [0.083], p=0.03), and in the apex-base direction in diastole (RMS: 0.087 [0.018] vs 0.11 [0.046], p=0.047). Non-responders had larger diastolic HDF ratio than responders (RMS: 0.89 [0.45] vs 0.67 [0.20], p=0.004; peak: 1.1 [0.51] vs 0.57 [0.40], p=0.01) (Figure 1). Receiver operating characteristic analysis of diastolic HDF ratio found an area under the curve of 0.88 (p=0.005). Identification of non-responders using diastolic HDF ratio with a specificity of 100%, resulted in a ratio of &amp;gt;0.87 for non-responders, with a sensitivity of 57%. Intragroup comparison found higher HDF ratio in systole than diastole for responders but not for non-responders (Figure 1). Conclusions Prediction of left ventricular remodelling following CRT may be optimized by hemodynamic force analysis from 4D flow CMR, while septal scar from LGE was not found indicative of CRT outcome in this pilot study. Larger-scale studies are required before clinical implementation of HDF analysis.Table 1Figure 1

Left atrial haemodynamic evaluation using 4D flow cardiac magnetic resonance imaging: application to hypertension and hypertrophic cardiomyopathy

Abstract Introduction Changes in left atrial (LA) hemodynamics have been suggested reflective of left ventricular (LV) disease progression. Kinetic energy (KE), viscous energy loss, and vorticity could be promising indices for the assessment of left atrial dynamics by time resolved four-dimensional cardiac magnetic resonance (4D flow CMR). Hypertrophic cardiomyopathy (HCM) patients are at risk of developing mitral regurgitation and left ventricular outflow tract obstruction, with poor outcome (1). Hypertensive myocardial remodelling has been suggested to be due to complex flow and tissue interactions leading to hypertrophy and diastolic dysfunction (2). Early detection of altered LA hemodynamic abnormalities may help non-invasive assessment, improving their long-term outcome (3). Purpose Quantitative and qualitative evaluation of left atrial hemodynamic metrics by 4D flow CMR in a cohort of HCM patients, hypertensive patients, and healthy controls with no known cardiovascular disease. Methods Eighteen HCM patients (50.0 [±18.2] years, 8 females), twenty-one hypertensive patients (55.2 [±6.2] years, 11 females), and seventeen controls (36.7 [±12.8] years, 1 female) underwent 4D flow CMR. Both patient groups had significantly higher LV-indexed mass, end-diastolic volume, and end-systolic volumes (P &amp;lt; 0.05). A semi-automated pipeline was used to segment the LA including pulmonary inflow and mitral outflow tracts using phase contrast magnetic resonance images derived from the 4D flow acquisition's phase and magnitude images. LA KE, viscous energy loss and vorticity were computed throughout the cardiac cycle. Results The HCM and hypertensive groups demonstrated significantly higher average KE integrated across the cardiac cycle (1.58 ± 0.79 and 1.32 ± 0.50 mJ respectively) compared to controls (1.20 ± 0.47 mJ) (P &amp;lt; 0.05), with the systolic curve in HCM showing the highest peak KE. Qualitatively, KE in the diastolic portion of the cardiac cycle appeared less variable between groups (Figure 1). Vorticity in HCM showed different configurations with loss of the central atrial vortex core (Figure 2). Viscous energy loss was also significantly higher in HCM patients confirming the increase in energy loss (Figure 2). Average KE across the cardiac cycle highly correlated with LA volume and pulmonary capillary wedge pressure calculated by a previously published regression method (4) (Pearson correlation: r= 0.76 and 0.71 respectively P &amp;lt; 0.05). There were also significant correlations with cardiac metrics such as indexed end-diastolic and indexed end-systolic volumes (Pearson correlation: r= 0.54 and 0.52 respectively P &amp;lt; 0.05) as well as indexed LV mass (r= 0.59 P &amp;lt; 0.05). Conclusion Hemodynamic metrics derived from 4D flow CMR may be valuable in establishing valuable predictive metrics of ventricular function. Integration of 4D flow MRI in clinical workflows could provide information that may be indicative of pathological onset before abnormal remodelling.Kinetic energy and viscous energy lossParticle pathlines and vorticity

4D-flow Cardiac Magnetic Resonance for the assEssmeNt of AOrtic Valve Repair with OzAki TEchnique.

4D-flow Cardiac Magnetic Resonance for the assEssmeNt of AOrtic Valve Repair with OzAki TEchnique.

Assessing atrial myopathy with cardiac magnetic resonance imaging in embolic stroke of undetermined source

BackgroundLeft atrial myopathy has been implicated in atrial fibrillation (AF)-related stroke and embolic stroke of undetermined source (ESUS). ObjectiveTo use advanced cardiac magnetic resonance (CMR) imaging techniques, including left atrial (LA) strain and 4D flow CMR, to identify atrial myopathy in patients with ESUS. Methods20 patients with ESUS and no AF or other cause for stroke, and 20 age and sex-matched controls underwent CMR with 4D flow analysis. Markers of LA myopathy were assessed including LA size, volume, ejection fraction, and strain. 4D flow CMR was performed to measure novel markers of LA stasis such as LA velocities and the LA residence time distribution time constant (RTDtc). These markers of LA myopathy were compared between the two groups. ResultsThere was no significant difference in: CMR-calculated LA velocities or LA total, passive or active ejection fractions between the groups. There was no significant difference in CMR-derived reservoir, conduit or contractile average longitudinal strain between the ESUS and control groups (22.9 vs 22.6%, p=0.379, 11.2 ± 3.5 vs 12.4 ± 2.6% p=0.224, 10.8 ± 3.2 vs 10.4 ± 2.3%, p=0.625 respectively). Similarly, RTDtc was not significantly longer in ESUS patients compared to controls (1.3 ± 0.2 vs 1.2 ± 0.2, p=0.1). ConclusionsThere were no significant differences in any CMR marker of atrial myopathy in ESUS patients compared to healthy controls, likely reflecting the multiple possible aetiologies of ESUS suggesting that the role LA myopathy plays in ESUS is smaller than previously thought.

4D Flow Cardiac Magnetic Resonance Atrial Flow Metrics in Early Ventricular Diastolic Dysfunction

4D Flow Cardiac Magnetic Resonance Atrial Flow Metrics in Early Ventricular Diastolic Dysfunction

4D flow cardiovascular magnetic resonance for the assessment of aortic valve repair with ozaki technique

Abstract Funding Acknowledgements Type of funding sources: None. Background Aortic valve neocuspidalization (Av-Neo) aims to replace the three aortic cusps with autologous pericardium pre-treated with glutaraldehyde and is becoming a valid alternative to traditional aortic valve replacement (AVR). 4D-flow cardiac magnetic resonance (4D-CMR) imaging of patients allows the derivation of shear stress on the aortic wall (WSS). Different studies support the presence of a link between increased WSS at 4D-CMR and the presence of histological alterations of the aortic wall. Purpose To compare the WSS of the ascending aorta in patients who underwent Av-Neo vs AVR with biological prostheses. Methods We performed 4D-flow CMR on 20 patients who underwent AV-Neo (Group A) or AVR (Group B), 10 patients for each group. Results The WSS in the Ozaki group was significantly lower in the proximal and distal aortic outer curvature compared to AVR patients (p 0.0179 and 0.0412, respectively, Figure 1 and 2). WSS levels remained significantly lower at the proximal aorta’s outer curvature segment in the Av-Neo population, also after adjusting the WSS for the ejection fraction and the LVOT-Aorta angle (p 0.02). Conclusions Av-neo hemodynamical features showed to be non-inferior to the ones provided by the commercially available bioprosthetic valves. Av-Neo procedures may be considered in patients affected by collagenopathy and other predisposing risk factors for the development of ascending aortic aneurism and aortic dissection other than classical AVR.

Characterization of impaired left ventricular mitral filling in HCM: A 4D-flow CMR study

Diastolic dysfunction is common and contributes to many clinical manifestations in hypertrophic cardiomyopathy (HCM). 4-dimensionnal (4D) flow cardiac magnetic resonance (CMR) sequence can assess left ventricular mitral filling. The purpose of this study was to determine if the peak early filling rate normalized to the filling volume (PEFR/FV), estimated from 4D-flow sequence can accurately assess impaired left ventricular mitral filling and predict clinical outcomes. This monocentric study included 44 HCM patients from a prospective HCM register and 44 healthy volunteers, who all underwent CMR with 4D-Flow sequence. Median follow-up time of HCM cohort patients was 2.3 years (interquartile range: 1.7 to 3.3 years). The predefined primary endpoint was a composite criteria that included syncope, onset of atrial fibrillation, admission for congestive heart failure with administration of diuretics, decision to perform septal reduction therapy due to persistent symptomatic obstruction, stroke, ventricular tachycardia or fibrillation and cardiac death. PEFR/FV was significantly lower in HCM cohort compared to healthy volunteers (P < 0.001). PFR/FV significantly correlated with BNP (r = −0.31, P < 0.001) and with E/E’ ratio (r = −0.56, p < 0.001). PEFR/FV according to NYHA status in HCM cohort was statistically different (P = 0.001). Primary endpoint occurred in 14 patients (32%). In univariate and bivariate adjusted cox-model analysis PEFR/FV < 2.61 s -1 was significantly associated with primary endpoint with Hazard Ratio ranging from [HR = 9.46 (95% CI 2.61–45.17, P < 0.001) to 15.21 (95%CI 3.51–80.22, P < 0.001)] according to succesive bivariate models. 4D-Flow can accurately assess left ventricular mitral filling with a good predictive value of clinical outcomes in HCM patients. Relation of PEFR/FV calculated with 4D flow in HCM.

4D-Flow Cardiovascular Magnetic Resonance Sequence for Aortic Assessment: Multi-Vendor and Multi-Magnetic Field Reproducibility in Healthy Volunteers.

Four-dimensional (4D) flow cardiac magnetic resonance (CMR) represents an emerging technique for non-invasive evaluation of the aortic flow. The aim of this study was to investigate a 4D-flow CMR sequence for the assessment of thoracic aorta comparing different vendors and different magnetic fields of MR scanner in fifteen healthy volunteers. CMR was performed on three different MRI scanners: one at 1.5 T and two at 3 T. Flow parameters and planar wall shear stress (WSS) were extracted from six transversal planes along the full thoracic aorta by three operators. Inter-vendor comparability as well as scan-rescan, intra- and interobserver reproducibility were examined. A high heterogeneity was found in the comparisons for each operator and for each scanner in the six transversal planes analysis (Friedman rank-sum test; p-value ≤ 0.05). Among all, the most reproducible measures were extracted for the sinotubular junction plane and for the flow parameters. Our results suggest that standardized procedures have to be defined to make more comparable and reproducible 4D-flow parameters and mainly, clinical impactfulness. Further studies on sequences development are needed to validate 4D-flow MRI assessment across vendors and magnetic fields also compared to a missing gold standard.

Quantifying Myocardial Blood Flow and Resistance Using 4D-Flow Cardiac Magnetic Resonance Imaging.

Ischaemia with nonobstructive coronary arteries is most commonly caused by coronary microvascular dysfunction but remains difficult to diagnose without invasive testing. Myocardial blood flow (MBF) can be quantified noninvasively on stress perfusion cardiac magnetic resonance (CMR) or positron emission tomography but neither is routinely used in clinical practice due to practical and technical constraints. Quantification of coronary sinus (CS) flow may represent a simpler method for CMR MBF quantification. 4D flow CMR offers comprehensive intracardiac and transvalvular flow quantification. However, it is feasibility to quantify MBF remains unknown. Patients with acute myocardial infarction (MI) and healthy volunteers underwent CMR. The CS contours were traced from the 2-chamber view. A reformatted phase contrast plane was generated through the CS, and flow was quantified using 4D flow CMR over the cardiac cycle and normalised for myocardial mass. MBF and resistance (MyoR) was determined in ten healthy volunteers, ten patients with myocardial infarction (MI) without microvascular obstruction (MVO), and ten with known MVO. MBF was quantified in all 30 subjects. MBF was highest in healthy controls (123.8 ± 48.4 mL/min), significantly lower in those with MI (85.7 ± 30.5 mL/min), and even lower in those with MI and MVO (67.9 ± 29.2 mL/min/) (P < 0.01 for both differences). Compared with healthy controls, MyoR was higher in those with MI and even higher in those with MI and MVO (0.79 (±0.35) versus 1.10 (±0.50) versus 1.50 (±0.69), P=0.02). MBF and MyoR can be quantified from 4D flow CMR. Resting MBF was reduced in patients with MI and MVO.

Automated 4D flow cardiac MRI pipeline to derive peak mitral inflow diastolic velocities using short-axis cine stack: two centre validation study against echocardiographic pulse-wave doppler

BackgroundMeasurement of peak velocities is important in the evaluation of heart failure. This study compared the performance of automated 4D flow cardiac MRI (CMR) with traditional transthoracic Doppler echocardiography (TTE) for the measurement of mitral inflow peak diastolic velocities.MethodsPatients with Doppler echocardiography and 4D flow cardiac magnetic resonance data were included retrospectively. An established automated technique was used to segment the left ventricular transvalvular flow using short-axis cine stack of images. Peak mitral E-wave and peak mitral A-wave velocities were automatically derived using in-plane velocity maps of transvalvular flow. Additionally, we checked the agreement between peak mitral E-wave velocity derived by 4D flow CMR and Doppler echocardiography in patients with sinus rhythm and atrial fibrillation (AF) separately.ResultsForty-eight patients were included (median age 69 years, IQR 63 to 76; 46% female). Data were split into three groups according to heart rhythm. The median peak E-wave mitral inflow velocity by automated 4D flow CMR was comparable with Doppler echocardiography in all patients (0.90 ± 0.43 m/s vs 0.94 ± 0.48 m/s, P = 0.132), sinus rhythm-only group (0.88 ± 0.35 m/s vs 0.86 ± 0.38 m/s, P = 0.54) and in AF-only group (1.33 ± 0.56 m/s vs 1.18 ± 0.47 m/s, P = 0.06). Peak A-wave mitral inflow velocity results had no significant difference between Doppler TTE and automated 4D flow CMR (0.81 ± 0.44 m/s vs 0.81 ± 0.53 m/s, P = 0.09) in all patients and sinus rhythm-only groups. Automated 4D flow CMR showed a significant correlation with TTE for measurement of peak E-wave in all patients group (r = 0.73, P < 0.001) and peak A-wave velocities (r = 0.88, P < 0.001). Moreover, there was a significant correlation between automated 4D flow CMR and TTE for peak-E wave velocity in sinus rhythm-only patients (r = 0.68, P < 0.001) and AF-only patients (r = 0.81, P = 0.014). Excellent intra-and inter-observer variability was demonstrated for both parameters.ConclusionAutomated dynamic peak mitral inflow diastolic velocity tracing using 4D flow CMR is comparable to Doppler echocardiography and has excellent repeatability for clinical use. However, 4D flow CMR can potentially underestimate peak velocity in patients with AF.

Left Ventricular Adverse Remodeling in Ischemic Heart Disease: Emerging Cardiac Magnetic Resonance Imaging Biomarkers

Post-ischemic left ventricular (LV) remodeling is a biologically complex process involving myocardial structure, LV shape, and function, beginning early after myocardial infarction (MI) and lasting until 1 year. Adverse remodeling is a post-MI maladaptive process that has been associated with long-term poor clinical outcomes. Cardiac Magnetic Resonance (CMR) is the best tool to define adverse remodeling because of its ability to accurately measure LV end-diastolic and end-systolic volumes and their variation over time and to characterize the underlying myocardial changes. Therefore, CMR is the gold standard method to assess in vivo myocardial infarction extension and to detect the presence of microvascular obstruction and intramyocardial hemorrhage, both associated with adverse remodeling. In recent times, new CMR quantitative biomarkers emerged as predictive of post-ischemic adverse remodeling, such as T1 mapping, myocardial strain, and 4D flow. Additionally, CMR T1 mapping imaging may depict infarcted tissue and assess diffuse myocardial fibrosis by using surrogate markers such as extracellular volume fraction, which may predict functional recovery or risk stratification of remodeling. Finally, there is emerging evidence supporting the utility of intracavitary blood flow kinetic energy and hemodynamic features assessed by the 4D flow CMR technique as early predictors of remodeling.

Abstract 10199: Increased Aortic Wall Shear Stress in Marfan Patients Long-Term After Proximal Grafting Assessed by 4D Flow Cardiac Magnetic Resonance

Introduction: For Marfan syndrome patients (MFS) with thoracic aortic aneurysms (TAA), prosthetic graft surgery provides lifesaving benefits, but adverse event risk persists in the native aorta for which mechanism is unclear. Sustained impact of proximal grafts on biomechanics within and distal to grafts is unknown. Methods: MFS patients with chronic (&gt; 6 month) proximal grafts were compared to non-surgical MFS (nsMFS) and age/sex matched controls: Wall shear stress (WSS) on 4D flow cardiac MRI and size (diameter) were quantified at aortic landmarks (ascending, arch, descending, thoracoabdominal). Results: 34 subjects were studied including MFS late (7.3±6.7 years) after graft implantation (n=12). Post-surgical MFS were of similar age (p=0.93) and sex (p=0.64) to controls but older than non-surgical MFS (45±10 vs 33±11 yo, p=0.01): In the ascending aorta (grafted territory), post-surgical MFS had higher WSS (1.17±0.55 Pa) than nsMFS (0.74±0.17 Pa) and controls (0.60±0.17 Pa; p=0.002 for trend). Similarly, in the (native) descending aorta, WSS was higher in post-surgical (1.06±0.24 Pa) than nsMFS (0.97±0.11) and controls (0.83±0.16; p=0.02) ( Figure ) paralleling results in the arch (p=0.06) and a similar trend in the thoracoabdominal aorta (p=0.12). Among the overall MFS cohort (n=23), proximal graft implantation associated with increased WSS in the ascending and descending aorta (both p&lt;0.01) in analyses controlling for age and aortic size in respective territories ( Table ). Conclusions: Prosthetic grafts yield sustained alterations in aortic biomechanics, including elevated WSS (a marker of adverse remodeling) in grafted regions and the distal native aorta.

Abstract 14731: Form and Function: 4D Flow Derived Hemodynamic Parameters in the Ascending Aorta is Reflective of Transverse Aortic Arch Dilation in Patients With Single Ventricle Physiology

Introduction: Reconstructed aortas in patients with single ventricle (SV) can dilate progressively over time, possibly due to abnormal flow patterns. Four-dimensional (4D) flow cardiac magnetic resonance imaging (CMR) can assess advanced hemodynamic parameters. This study utilizes 4D flow CMR to assess the association between ascending aorta (AAo) 4D flow dynamics of vorticity, viscous energy loss (EL) and kinetic energy (KE) with arch anatomy in SV patients. Methods: This was a retrospective single center study of all patients with SV who underwent 4D flow CMR from June 2021-present. Vorticity, KE and EL were calculated over the segmented three-dimensional AAo, and values were normalized to cardiac index (CI). Cross-sectional areas of the aortic root, AAo and transverse aorta were indexed to body surface area. Linear regression was used to determine associations between hemodynamic parameters and arch anatomy. Results: 20 pts met inclusion criteria; 5 were excluded due to incomplete datasets. The remaining 15 pts had a median age of 57 months (IQR 31;117.5). Ten (66%) had a systemic RV, 13 (86%) had a reconstructed aorta and 40% were after the Fontan operation. Peak and mean vorticity in the AAo were positively associated with transverse arch area. Additionally, there was a positive association between both total EL and EL index, and transverse arch area. (see table) Conclusions: Higher vorticity and EL in the AAo are associated with and reflective of higher transverse arch areas (i.e. dilation) in SV pts. In depth research in a prospective, longitudinal cohort is warranted to better understand this relationship and the geometry relative to hemodynamics. Furthermore, correlation of 4D flow metrics with clinical outcomes may provide novel insights into modifiable risk factors in this patient population

Quantitative evaluation of aortic valve regurgitation in 4D flow cardiac magnetic resonance: at which level should we measure?

PurposeTo find the best level to measure aortic flow for quantification of aortic regurgitation (AR) in 4D flow CMR.MethodsIn 27 congenital heart disease patients with AR (67% male, 31 ± 16 years) two blinded observers measured antegrade, retrograde, net aortic flow volumes and regurgitant fractions at 6 levels in 4D flow: (1) below the aortic valve (AV), (2) at the AV, (3) at the aortic sinus, (4) at the sinotubular junction, (5) at the level of the pulmonary arteries (PA) and (6) below the brachiocephalic trunk. 2D phase contrast (2DPC) sequences were acquired at the level of PA. All patients received prior transthoracic echocardiography (TTE) with AR severity grading according to a recommended multiparametric approach.ResultsAfter assigning 2DPC measurements into AR grading, agreement between TTE AR grading and 2DPC was good (κ = 0.88). In 4D flow, antegrade flow was similar between the six levels (p = 0.87). Net flow was higher at level 1–2 than at levels 3–6 (p < 0.05). Retrograde flow and regurgitant fraction at level 1–2 were lower compared to levels 3–6 (p < 0.05). Reproducibility (inter-reader agreement: ICC 0.993, 95% CI 0.986–0.99; intra-reader agreement: ICC 0.982, 95%CI 0.943–0.994) as well as measurement agreement between 4D flow and 2DPC (ICC 0.994; 95%CI 0.989 – 0.998) was best at the level of PA.ConclusionFor estimating severity of AR in 4D flow, best reproducibility along with best agreement with 2DPC measurements can be expected at the level of PA. Measurements at AV or below AV might underestimate AR.