Flow Cardiovascular Magnetic Resonance Research Articles

Wall Shear Stress Measured with 4D Flow CMR Correlates with Biomarkers of Inflammation and Collagen Synthesis in Mild-to-Moderate Ascending Aortic Dilation and Tricuspid Aortic Valves.

Understanding the mechanisms underlying ascending aortic dilation is imperative for refined risk stratification of these patients, particularly among incidentally identified patients, most commonly presenting with tricuspid valves. The aim of this study was to explore associations between ascending aortic hemodynamics, assessed using four-dimensional flow cardiovascular magnetic resonance imaging (4D Flow CMR), and circulating biomarkers in aortic dilation. Forty-seven cases with aortic dilation (diameter ≥40 mm) and 50 sex-and age-matched controls (diameter <40 mm), all with tricuspid aortic valves, underwent 4D flow CMR and venous blood sampling. Associations between flow displacement, wall shear stress (WSS), and oscillatory shear index in the ascending aorta derived from 4D Flow CMR, and biomarkers including interleukin-6, collagen type I α1 chain, metalloproteinases (MMPs), and inhibitors of MMPs derived from blood plasma, were investigated. Cases with dilation exhibited lower peak systolic WSS, higher flow displacement, and higher mean oscillatory shear index compared to controls without dilation. No significant differences in biomarkers were observed between the groups. Correlations between hemodynamics and biomarkers were observed, particularly between maximum time-averaged WSS and interleukin-6 (r = 0.539, p < 0.001), and maximum oscillatory shear index and collagen type I α1 chain (r = -0.575, p < 0.001 in cases). Significant associations were discovered between 4D flow CMR derived whole-cardiac cycle WSS and circulating biomarkers representing inflammation and collagen synthesis, suggesting an intricate interplay between hemodynamics and the processes of inflammation and collagen synthesis in patients with early aortic dilation and tricuspid aortic valves.

Aortic geometry and long-term outcome in patients with a repaired coarctation

ObjectiveThis study aims to compare aortic morphology between repaired coarctation patients and controls, and to identify aortic morphological risk factors for hypertension and cardiovascular events (CVEs) in coarctation patients.MethodsRepaired coarctation...

Aortic flow is abnormal in HFpEF.

Turbulent aortic flow makes the cardiovascular system less effective. It remains unknown if patients with heart failure with preserved ejection fraction (HFpEF) have disturbed aortic flow. This study sought to investigate advanced markers of aortic flow disturbances in HFpEF. This case-controlled observational study used four-dimensional flow cardiovascular magnetic resonance derived, two-dimensional phase-contrast reformatted plane data at an orthogonal plane just above the sino-tubular junction. We recruited 10 young healthy controls (HCs), 10 old HCs and 23 patients with HFpEF. We analysed average systolic aortic flow displacement (FDsavg), systolic flow reversal ratio (sFRR) and pulse wave velocity (PWV). In a sub-group analysis, we compared old HCs versus age-gender-matched HFpEF (N=10). Differences were significant in mean age (P<0.001) among young HCs (22.9±3.5 years), old HCs (60.5±10.2 years) and HFpEF patients (73.7±9.7 years). FDsavg, sFRR and PWV varied significantly (P<0.001) in young HCs (8±4%, 2±2%, 4±2m/s), old HCs (16±5%, 7±6%, 11±8m/s), and HFpEF patients (23±10%, 11±10%, 8±3). No significant PWV differences existed between old HCs and HFpEF.HFpEF had significantly higher FDsavg versus old HCs (23±10% vs 16±5%, P<0.001). A FDsavg > 17.7% achieved 74% sensitivity, 70% specificity for differentiating them. sFRR was notably higher in HFpEF (11±10% vs 7±6%, P<0.001). A sFRR > 7.3% yielded 78% sensitivity, 70% specificity in differentiating these groups. In sub-group analysis, FDsavg remained distinctly elevated in HFpEF (22.4±9.7% vs 16±4.9%, P=0.029). FDsavg of >16% showed 100% sensitivity and 70% specificity (P=0.01). Similarly, sFRR remained significantly higher in HFpEF (11.3±9.5% vs 6.6±6.4%, P=0.007). A sFRR of >7.2% showed 100% sensitivity and 60% specificity (P<0.001). Aortic flow haemodynamics namely FDsavg and sFRR are significantly affected in ageing and HFpEF patients.

Four-dimensional flow cardiovascular magnetic resonance aortic cross-sectional pressure changes and their associations with flow patterns in health and ascending thoracic aortic aneurysm

BackgroundAscending thoracic aortic aneurysm (ATAA) is a silent and threatening dilation of the ascending aorta (AscAo). Maximal aortic diameter which is currently used for ATAA patients management and surgery planning has been shown to inadequately characterize risk of dissection in a large proportion of patients. Our aim was to propose a comprehensive quantitative evaluation of aortic morphology and pressure-flow-wall associations from 4D flow MRI data in healthy aging and in patients with ATAA. MethodsWe studied 17 ATAA patients (64.7±14.3 years, 5 females) along with 17 age- and sex-matched healthy controls (59.7±13.3 years, 5 females) and 13 younger healthy subjects (33.5±11.1 years, 4 females). All subjects underwent an MRI exam including 4D flow and 3D anatomical images of the aorta. This latter dataset was used for aortic morphology measurements including AscAo maximal diameter (iDMAX) and volume, indexed to body surface area. 4D flow MRI data were used to estimate: 1) cross-sectional local AscAo spatial (∆PS) and temporal (∆PT) pressure changes as well as the distance (∆DPS) and time duration (∆TPT) between local pressure peaks, 2) AscAo maximal wall shear stress (WSSMAX) at peak systole, 3) AscAo flow vorticity amplitude (VMAX), duration (VFWHM) and eccentricity (VECC). ResultsConsistency of flow and pressure indices was demonstrated through their significant associations with AscAo iDMAX (WSSMAX: r=-0.49, p<0.001; VECC:r=-0.29, p=0.045; VFWHM:r=0.48, p<0.001; ∆DPS:r=0.37, p=0.010; ∆TPT:r=-0.52, p<0.001) and indexed volume (WSSMAX:r=-0.63, VECC:r=-0.51, VFWHM:r=0.53, ∆DPS:r=0.54, ∆TPT:r=-0.63, p<0.001 for all). Intra-AscAo cross-sectional pressure difference, ∆PS, was significantly and positively associated with both VMAX (r=0.55, p=0.002) and WSSMAX (r=0.59, p<0.001) in the 30 healthy subjects (48.3±18.0 years). Associations remained significant after adjustment for iDMAX, age and systolic blood pressure. Superimposition of ATAA patients to normal aging trends between ∆PS and WSSMAX as well as VMAX allowed identifying patients with substantially high pressure differences concomitant with AscAo dilation. ConclusionLocal variations in pressures within ascending aortic cross-sections derived from 4D flow MRI were associated with flow changes, as quantified by vorticity, and with stress exerted by blood on the aortic wall, as quantified by wall shear stress. Such flow-wall and pressure interactions might help for the identification of at-risk patients.

Kiosk 3R-TB-01 - Improved Quantitative Flow Analysis of Main and Branch Pulmonary Arteries Distal to the Vortex in Repaired Tetralogy of Fallot- a Single Center 4D Flow Cardiovascular Magnetic Resonance Study

Kiosk 3R-TB-01 - Improved Quantitative Flow Analysis of Main and Branch Pulmonary Arteries Distal to the Vortex in Repaired Tetralogy of Fallot- a Single Center 4D Flow Cardiovascular Magnetic Resonance Study

Diastolic function assessment with four-dimensional flow cardiovascular magnetic resonance using automatic deep learning E/A ratio analysis

BackgroundDiastolic left ventricular dysfunction is a powerful contributor to the symptoms and prognosis of patients with heart failure. In patients with depressed left ventricular systolic function the EA ratio is the first step to defining the grade of diastolic dysfunction. Doppler echocardiography is the preferred imaging technique for diastolic function assessment, while CMR is less established as a method. Previous 4D Flow-based studies have looked at the EA ratio proximally to the mitral valve, requiring manual interaction. In this study we compare an automated, deep learning-based, and two semiautomated approaches for 4D Flow CMR-based EA ratio assessment to conventional, gold standard echo-based methods. MethodsNinety-seven subjects with chronic ischemic heart disease underwent a cardiac echo followed by an MRI investigation. 4D Flow-based EA ratio values were computed using three different approaches; two semi-automated, assessing the EA ratio by measuring the inflow velocity (MVvel) and the inflow volume (MVflow) at the mitral valve plane, and one fully automated, creating a full LV segmentation using a deep learning-based method within which the EA ratio could be assessed without constraint to the mitral plane (LVvel). ResultsMVvel, MVflow, and LVvel EA ratios were strongly associated with Echo EA ratio (R2= 0.60, 0.58, 0.72). LVvel peak E and A showed moderate association to Echo peak E and A, while MVvel values were weakly associated. MVvel and MVflow EA ratios were very strongly associated with LVvel (R2= 0.84, 0.86). MVvel peak E was moderately associated with LVvel, while peak A showed strong association (R2= 0.26, 0.57). Discussion and ConclusionPeak E, peak A and EA ratio are integral to the assessment of diastolic dysfunction and may expand the utility of CMR studies in patients with cardiovascular disease. While underestimation of absolute peak E and A velocities was noted, the EA ratio measured with all three 4D Flow methods was strongly associated with the gold standard Doppler echocardiography. The automatic, deep learning-based method performed best, with the most favorable runtime of ~40seconds. As both semiautomatic methods associated very strongly to LVvel, they could be employed as an alternative for estimation of EA ratio.

Hemodynamics and plasma biomarkers in individuals with mild-to-moderate ascending aortic dilatation and tricuspid aortic valves

Abstract Background Ascending aortic (AA) dilatation is a silent disease that requires frequent follow-up measurements of the AA diameter. Unfortunately, the AA diameter is an insufficient predictor of future growth and complications. Hemodynamic and circulating biomarkers represent promising ways of improving the risk stratification in AA dilatation. Most patients with AA dilatation have tricuspid aortic valves (TAV). However, previous studies have mainly focused on AA dilation in individuals with bicuspid aortic valves (BAV) using either hemodynamic or circulating biomarkers separately. Purpose To assess the relationship between hemodynamics in the AA and circulating biomarkers in individuals with mild-to-moderate AA dilatation and age-and-sex matched controls with TAV. Methods The study cohort of individuals with mild-to-moderate AA dilatation were identified based on AA diameter on coronary CT angiography in the population-based Swedish CardioPulmonary BioImage Study (SCAPIS) in Linköping. 54 cases with AA diameter &amp;gt;= 40 mm and 50 controls with AA diameter &amp;lt;40 mm (mean age 59, 19% female) underwent 4D Flow cardiovascular magnetic resonance imaging (CMR). The 4D Flow CMR images were processed to compute mean and maximum velocities, wall shear stress (WSS), flow displacement (FD) at peak systole, and oscillatory shear index (OSI) in the AA. Markers of collagen synthesis and degradation; type I collagen α1 chain (COL1α1), matrix metalloproteinase (MMP)-1,-2,-3,-9,-12) and their inhibitors (TIMP-1,-2,-3,-4), were quantified in plasma (n=104). High sensitivity C-reactive protein and interleukin(IL)-6 were used to assess systemic inflammation. Results FD at the location of maximum dilatation, mean FD and mean OSI were higher in cases compared to controls. Mean velocity, mean WSS and maximum WSS were lower in cases compared to controls. None of the circulating biomarkers differed significantly between cases and controls. Interestingly, several circulating biomarkers correlated with hemodynamics markers in the whole cohort. COL1α1, MMP-2 and TIMP-2 correlated inversely with max OSI (r=-0.342, p=0.001; r=-0.277, p=0.006; r=-0.238, p=0.018, respectively) while MMP-3 correlated positively with mean velocity (r=0.274, p=0.006), mean WSS (r=0.270, p=0.007), max WSS (r=0.220, p=0.029), and inversely with FD at the location of maximum dilatation (r=-0.218, p=0.031). TIMP-4 correlated with mean OSI (r=-0.284, p=0.005). Conclusions Several hemodynamic markers obtained with 4D Flow CMR were altered in mild-to-moderate AA dilatation with TAV, while circulating biomarkers did not differ from controls. However, significant correlations were identified between several biomarkers and hemodynamic markers. We therefore speculate that the levels of circulating biomarkers may be altered as the disease progresses. Future studies should examine the implications of these novel findings along the trajectory of AA dilation and its association with complication risk.Methods figureHemodynamics markers table

Abstract 14833: Association of RV Hemodynamics From 4D Flow CMR With RV Restrictive Physiology From Pediatric to Adult Repaired Tetralogy of Fallot

Introduction: Right ventricular restrictive physiology (RVRP) is common after repair of Tetralogy of Fallot (rTOF), especially with residual pulmonary regurgitation. Four-dimensional (4D) flow cardiovascular magnetic resonance (CMR) quantitates biventricular blood flow components and kinetic energy (KE) parameters, but their association with RVRP is unclear. We aimed to study 4D flow CMR parameters in adult and pediatric rTOF patients vs healthy controls and associations of 4D flow parameters with RVRP in rTOF. Methods: 103 rTOF patients (40 pediatric, 63 adult; age 24±17 years; 53M:50F) and 171 healthy controls (14 pediatric, 157 adult; age 40±15 years; 97M:74F) were prospectively recruited from centers in Singapore (2) and China (1) to undergo 4D flow CMR on multi-vendor scanners. LV and RV flow components—direct flow, retained inflow, delayed ejection flow and residual volume—and KE parameters (normalized to end-diastolic volume, KEi EDV )—global, peak systolic, average systolic, average diastolic, peak E-wave and peak A-wave—were analyzed. KE discordance was calculated as the ratio of RV and LV average systolic KEi EDV . Results: See Table. RVRP was identified in 70 patients (68%). rTOF with RVRP exhibited higher median RV stroke volume index, RV ejection fraction, RV direct flow, RV peak E-wave and E-wave/A-wave, and lower RV residual volume compared to rTOF without RVRP (all P&lt;0.05). Using binary multivariable logistic regression analysis—and after adjustment for age, pulmonary regurtitation, LV and RV ejection fraction, RV direct flow was found to be independently associated with RVRP in rTOF (P&lt;0.001). Conclusion: Patients with RVRP had higher RV direct flow, RVEF and RV peak E-wave energy, indicating the potential compensatory adaptations in patients with RVRP.

Abstract 16562: Subclinical Flow Inefficiencies in Non-Obstructive Hypertrophic Cardiomyopathy Subgroups Revealed by 4D Flow Cardiovascular Magnetic Resonance

Background Patients with non-obstructive hypertrophic cardiomyopathy (nHCM) may exhibit flow inefficiencies despite normal flow profiles on transthoracic echocardiogram. We investigated whether left ventricular (LV) kinetic energy (KE) and hemodynamic forces (HDF) on 4D flow CMR are abnormal in nHCM, and examined the impact of genotype and hypertrophy phenotype on flow profiles. Methods 90 participants (70 HCM without echocardiographic outflow tract obstruction and 20 healthy controls) underwent 4D flow CMR. Patients were categorized as phenotype positive (P+) if they had LV hypertrophy (≥15mm or ≥13mm with an HCM family history), or phenotype negative (P-) referring to pre-hypertrophic pathogenic sarcomeric variant carriers. LV KE, HDF and transversal/longitudinal HDF ratio were computed from 4D flow CMR. Results P+ patients and controls were of similar age, but P- were younger. P+, P- and controls had comparable LV ejection fraction on CMR, and LV outflow tract pressure gradients and diastolic velocities on echocardiography (Table 1). Systolic KE was higher in P+ compared to controls (Table 1, Figure 1). Early diastolic KE was higher in P- than P+, reflecting younger P-, but did not differ between P+ and controls. Late diastolic KE was higher in P+ versus P- and controls. Systolic HDF ratio was higher in P+ than controls (Table 1, Figure 1). Diastolic HDF and HDF ratio were similar between P+ and controls. Conclusion Despite comparable flow velocities on echocardiography, nHCM exhibited higher systolic KE and HDF ratio, and late diastolic KE on 4D flow CMR relative to controls. Both the extent and pattern of hypertrophy are important determinants of abnormalities in KE and HDF.

Oscillatory shear stress is elevated in patients with bicuspid aortic valve and aortic regurgitation: a 4D flow cardiovascular magnetic resonance cross-sectional study.

Patients with bicuspid aortic valve (BAV) and aortic regurgitation have higher rate of aortic complications compared with patients with BAV and stenosis, as well as BAV without valvular disease. Aortic regurgitation alters blood haemodynamics not only in systole but also during diastole. We therefore sought to investigate wall shear stress (WSS) during the whole cardiac cycle in BAV with aortic regurgitation. Fifty-seven subjects that underwent 4D flow cardiovascular magnetic resonance imaging were included: 13 patients with BAVs without valve disease, 14 BAVs with aortic regurgitation, 15 BAVs with aortic stenosis, and 22 normal controls with tricuspid aortic valve. Peak and time averaged WSS in systole and diastole and the oscillatory shear index (OSI) in the ascending aorta were computed. Student's t-tests were used to compare values between the four groups where the data were normally distributed, and the non-parametric Wilcoxon rank sum tests were used otherwise. BAVs with regurgitation had similar peak and time averaged WSS compared with the patients with BAV without valve disease and with stenosis, and no regions of elevated WSS were found. BAV with aortic regurgitation had twice as high OSI as the other groups (P ≤ 0.001), and mainly in the outer mid-to-distal ascending aorta. OSI uniquely characterizes altered WSS patterns in BAVs with aortic regurgitation, and thus could be a haemodynamic marker specific for this specific group that is at higher risk of aortic complications. Future longitudinal studies are needed to verify this hypothesis.

Quantifying 4D flow cardiovascular magnetic resonance vortices in patients with pulmonary hypertension: A pilot study.

In this 4D flow cardiovascular magnetic resonance (CMR) study, vortical blood flow in the main pulmonary artery (MPA) is quantified using circulation (ᴦ), a metric used in fluid dynamics to quantify the rotational components of flow. Circulation (ᴦ) is a 4D flow CMR metric that quantifies the vortical blood flow pattern in the MPA of patients with pulmonary hypertension (PH), distinguishes them from healthy controls, and shows high correlation with invasive markers of PH severity.

Intraventricular 4D flow cardiovascular magnetic resonance for assessing patients with heart failure with preserved ejection fraction: a pilot study.

Diagnosing heart failure with preserved ejection fraction (HFpEF) remains challenging. Intraventricular four-dimensional flow (4D flow) phase-contrast cardiovascular magnetic resonance (CMR) can assess different components of left ventricular (LV) flow including direct flow, delayed ejection, retained inflow and residual volume. This could be utilised to identify HFpEF. This study investigated if intraventricular 4D flow CMR could differentiate HFpEF patients from non-HFpEF and asymptomatic controls. Suspected HFpEF patients and asymptomatic controls were recruited prospectively. HFpEF patients were confirmed using European Society of Cardiology (ESC) 2021 expert recommendations. Non-HFpEF patients were diagnosed if suspected HFpEF patients did not fulfil ESC 2021 criteria. LV direct flow, delayed ejection, retained inflow and residual volume were obtained from 4D flow CMR images. Receiver operating characteristic (ROC) curves were plotted. 63 subjects (25 HFpEF patients, 22 non-HFpEF patients and 16 asymptomatic controls) were included in this study. 46% were male, mean age 69.8 ± 9.1years. CMR 4D flow derived LV direct flow and residual volume could differentiate HFpEF vs combined group of non-HFpEF and asymptomatic controls (p < 0.001 for both) as well as HFpEF vs non-HFpEF patients (p = 0.021 and p = 0.005, respectively). Among the 4 parameters, direct flow had the largest area under curve (AUC) of 0.781 when comparing HFpEF vs combined group of non-HFpEF and asymptomatic controls, while residual volume had the largest AUC of 0.740 when comparing HFpEF and non-HFpEF patients. CMR 4D flow derived LV direct flow and residual volume show promise in differentiating HFpEF patients from non-HFpEF patients.

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.

Fluid dynamics by 4D flow CMR in Marfan and Loeys-Dietz patients before and after valve sparing aortic root replacement

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Instituto de Salud Carlos III (Spain), Sociedad Española de Cardiología Introduction Patients with Marfan or Loeys-Dietz syndrome present abnormal aortic flow patterns in the arch and the proximal descending aorta that may contribute to aortic dilation (1,2). Valve sparing aortic root replacement, which is effective in reducing the risk of aortic dissection in case of severe dilation, may also normalize flow patterns beyond the replaced aorta and potentially slow its progressive aortic dilation. Purpose To assess aortic flow dynamics in these patients with Marfan or Loeys-Dietz by 4D flow cardiovascular magnetic resonance (CMR) before and after valve sparing aortic root replacement (David surgery), and to compare the results with those of healthy volunteers (HV). Methods Patients with Marfan or Loeys-Dietz syndrome underwent two non-contrast enhanced 4D flow CMR, one before and another after undergoing David surgery. Healthy volunteers matched for age, sex and BSA were also included for comparison. Maximum velocity, in-plane rotational flow (IRF), systolic flow reversal ratio (SFRR) and wall shear stress (WSS) magnitude and its axial and circumferential components were obtained at 24 planes covering the thoracic aorta from the sinotubular junction to the descending aorta at the diaphragmatic level (3–5). Results Sixteen patients and 21 healthy volunteers were included. Demographic and clinical data is presented in Table. The mean time between the CMR prior and posterior to surgery was 15 months. Compared to HV, patients with CTD before intervention presented lower maximum velocity at the proximal ascending aorta (Figure 1A), lower IRF and circumferential WSS at the arch and the proximal descending aorta (Figure 1B and F), lower magnitude and axial WSS at the proximal ascending and descending aorta (Figure 1E and D), and increased SFRR at the proximal descending aorta (Figure 1C). The intervention completely restored maximum velocity and partially-restored physiological helical flow and circumferential WSS, but barely improved axial WSS and SFRR. Conclusion Valve sparing aortic root replacement in patients with Marfan or Loeys-Dietz syndrome partially restore to physiological level both in-plane rotational flow and circumferential wall shear stress in the descending aorta.

4D Flow Cardiovascular Magnetic Resonance-Derived Flow Biomarkers for Early Detection of Flow Abnormalities: A Multicohort New Zealand Based Study

Four-dimensional (4D) flow cardiovascular magnetic resonance (4D flow CMR) imaging has evolved as a versatile imaging technique for the assessment of cardiovascular three-dimensional time resolved haemodynamics. This study aimed to examine the utility and metrics derived from 4D flow CMR in different patient cohorts. Controls (n=26), adult tetralogy of Fallot (rToF; n=14), and left ventricular hypertrophy (LVH; n=10) patients were scanned at the Centre of Advanced MRI, University of Auckland. Quantification of flow and examination of between-group differences were performed. Intraclass correlation coefficients (ICC) were used to correlate 4D and 2D CMR. Forward flow rates averaged in the pulmonary veins were significantly greater in LVH than controls (79.11±54.24 mL/sec vs 32.58±35.98 mL/sec, respectively, p<0.05), as was the pulmonary venous atrial reversal peak velocity (–0.44±0.23 m/sec vs –0.13±0.27 m/sec, respectively, p<0.05). Mitral indices of net flow and peak velocity expressed no significant between-group differences. In the rToF group, quantification of pulmonary artery and branches demonstrated a good correlation with 2D CMR. Greatest correlation was between pulmonary artery backward flow (difference of s–2.50±6.91 mL/cycle, ICC 0.96). In relation to pulmonary valve regurgitation categorisation, 1 of 14 cases were differently categorised using 4D flow (ICC 0.91). Quantification of flow with 4D flow CMR was feasible, with a single acquisition introducing an array of flow metrics that may be valuable for the evaluation of various conditions. Larger scale investigations of 4D flow CMR are required, with wider-scale application in routine clinical workflows.

'Conventional' haemodynamics even in the quadricuspid aortic valve: clinical recognition using multimodality imaging.

A 76-year-old male with congestive heart failure, accompanied by dyspnoea and irregular rhythm, was transferred to our hospital for treatment of congestive heart failure (NYHAIII/IV). Atrial fibrillation was confirmed by electrocardiography, and transoesophageal echocardiography (TEE) for electrical cardioversion was performed due to poor response to medical therapy. Two- and three-dimensional TEE revealed a quadricuspid aortic valve (QAV) with central leaflet malcoaptation and restriction of valve leaflet opening (Panels A and B; Supplementary data online, Videos S1 and S2). After electrical cardioversion, transthoracic echocardiography showed severe aortic stenosis with a 4.9 m/s peak aortic valve flow velocity, mean pressure gradient of 56 mm Hg (Panel C), and severe aortic regurgitation; the regurgitant volume was 61 mL/beat, and vena contracta width was 6.1 mm (Panel D; Supplementary data online, Video S3). Multi-detector row computed tomography confirmed the QAV and showed no dilatation of the ascending aorta (diameter, 34 mm) (Panels E and F). Four-dimensional flow cardiovascular magnetic resonance was confirmed that blood flow in the ascending aorta had a normal flow pattern; peak systolic wall shear stress values were not high, and symmetrical helical flow was observed (Panels G and H; Supplementary data online, Videos S4 and S5). Based on these results, TAVI was also considered, but we determined that simultaneous intervention for atrial fibrillation was necessary. Therefore, surgical aortic valve replacement (bioprosthetic valve), pulmonary vein isolation, and left atrial appendage closure were performed (Panels I and J). This case underlines the importance of multimodality approach to the diagnosis and treatment strategy of QAV.

Population-based reference values for 4D flow MRI derived aortic blood flow parameters

Objective. This study assesses age-related differences of thoracic aorta blood flow profiles and provides age- and sex-specific reference values using 4D flow cardiovascular magnetic resonance (CMR) data. Approach. 126 volunteers (age 20–80 years, female 51%) underwent 4D flow CMR and 12 perpendicular analysis planes in the thoracic aorta were specified. For these planes the following parameters were evaluated: body surface area-adjusted aortic area (A′), normalized flow displacement (NFD), the degree of wall parallelism (WPD), the minimal relative cross-sectional area through which 80% of the volume flow passes (A80) and the angle between flow direction and centerline (α). Main results. Age-related differences in blood flow parameters were seen in the ascending aorta with higher values for NFD and angle and lower values for WPD and A80 in older subjects. All parameters describing blood flow patterns correlated with the cross-sectional area in the ascending aorta. No relevant sex-differences regarding blood flow profiles were found. Significance. These age- and sex-specific reference values for quantitative parameters describing blood flow within the aorta might help to study the clinical relevance of flow profiles in the future.

Evaluation of left ventricular blood flow kinetic energy in patients with hypertension by four-dimensional flow cardiovascular magnetic resonance imaging: a preliminary study.

To evaluate the intra-cavity left ventricular (LV) blood flow kinetic energy (KE) parameters using four-dimensional (4D) flow cardiovascular magnetic resonance (CMR) in patients with hypertension (HTN). Forty-two HTN patients and twenty age-/gender-matched healthy controls who underwent CMR including cines, pre-/post-T1 mapping, and whole-heart 4D flow imaging were retrospectively evaluated. HTN patients were further divided into two subgroups: with preserved ejection fraction (HTN-pEF) and with reduced ejection fraction (HTN-rEF). KE parameters were indexed to LV end-diastolic volume (EDV) to obtain averaged LV, minimal, systolic, diastolic, peak E-wave, peak A-wave, E-wave, and A-wave KEiEDV, as well as the proportion of in-plane LV KE (%), the time difference (TD). These parameters were compared between the HTN group and healthy controls, also between two subgroups. The correlation of LV blood flow KE parameters with LV function and extracellular volume fraction (ECV) were analyzed in the HTN group using multivariate regression analysis. Peak E-wave KEiEDV in the HTN group was significantly lower (p = 0.01), while in-plane KE and TD were significantly higher (all p < 0.01) than those in healthy controls. Compared to the HTN-pEF subgroup, the proportion of in-plane KE and TD was significantly increased in the HTN-rEF subgroup (all p < 0.01). Only the proportion of in-plane KE demonstrated an independent correlation with ECV (β* = 0.59, p < 0.01). The decreased peak E-wave KEiEDV and the increased proportion of in-plane KE, TD reflected the alterations of LV blood flow in HTN patients, and the proportion of in-plane KE was independently associated with ECV. • 4D flow CMR demonstrated that the peak E-wave KEiEDV was decreased, while the in-plane KE and time difference (TD) were increased in hypertensive (HTN) patients. • The proportion of in-plane KE and TD was further increased in HTN patients with reduced ejection fraction than in HTN patients with preserved ejection fraction, and the proportion of in-plane KE was independently associated with extracellular volume fraction in HTN patients. • 4D flow CMR intra-cavity blood flow KE parameters might reveal the LV hemodynamic status in preclinical HTN patients.

Changes of aortic hemodynamics after aortic valve replacement-A four dimensional flow cardiovascular magnetic resonance follow up study.

Non-invasive assessment of aortic hemodynamics using four dimensional (4D) flow magnetic resonance imaging (MRI) provides new information on blood flow patterns and wall shear stress (WSS). Aortic valve stenosis (AS) and/or bicuspid aortic valves (BAV) are associated with altered aortic flow patterns and elevated WSS. Aim of this study was to investigate changes in aortic hemodynamics over time in patients with AS and/or BAV with or without aortic valve replacement. We rescheduled 20 patients for a second 4D flow MRI examination, whose first examination was at least 3 years prior. A total of 7 patients received an aortic valve replacement between baseline and follow up examination (=operated group = OP group). Aortic flow patterns (helicity/vorticity) were assessed using a semi-quantitative grading approach from 0 to 3, flow volumes were evaluated in 9 planes, WSS in 18 and peak velocity in 3 areas. While most patients had vortical and/or helical flow formations within the aorta, there was no significant change over time. Ascending aortic forward flow volumes were significantly lower in the OP group than in the NOP group at baseline (NOP 69.3 mL ± 14.2 mL vs. OP 55.3 mL ± 1.9 mL p = 0.029). WSS in the outer ascending aorta was significantly higher in the OP group than in the NOP group at baseline (NOP 0.6 ± 0.2 N/m2 vs. OP 0.8 ± 0.2 N/m2, p = 0.008). Peak velocity decreased from baseline to follow up in the aortic arch only in the OP group (1.6 ± 0.6 m/s vs. 1.2 ± 0.3 m/s, p = 0.018). Aortic valve replacement influences aortic hemodynamics. The parameters improve after surgery.

Age- and sex-specific reference values of biventricular flow components and kinetic energy by 4D flow cardiovascular magnetic resonance in healthy subjects

BackgroundAdvances in four-dimensional flow cardiovascular magnetic resonance (4D flow CMR) have allowed quantification of left ventricular (LV) and right ventricular (RV) blood flow. We aimed to (1) investigate age and sex differences of 4D flow CMR-derived LV and RV relative flow components and kinetic energy (KE) parameters indexed to end-diastolic volume (KEiEDV) in healthy subjects; and (2) assess the effects of age and sex on these parameters. MethodsWe performed 4D flow analysis in 163 healthy participants (42% female; mean age 43 ± 13 years) of a prospective registry study (NCT03217240) who were free of cardiovascular diseases. Relative flow components (direct flow, retained inflow, delayed ejection flow, residual volume) and multiple phasic KEiEDV (global, peak systolic, average systolic, average diastolic, peak E-wave, peak A-wave) for both LV and RV were analysed. ResultsCompared with men, women had lower median LV and RV residual volume, and LV peak and average systolic KEiEDV, and higher median values of RV direct flow, RV global KEiEDV, RV average diastolic KEiEDV, and RV peak E-wave KEiEDV. ANOVA analysis found there were no differences in flow components, peak and average systolic, average diastolic and global KEiEDV for both LV and RV across age groups. Peak A-wave KEiEDV increased significantly (r = 0.458 for LV and 0.341 for RV), whereas peak E-wave KEiEDV (r = − 0.355 for LV and − 0.318 for RV), and KEiEDV E/A ratio (r = − 0.475 for LV and − 0.504 for RV) decreased significantly, with age. ConclusionThese data using state-of-the-art 4D flow CMR show that biventricular flow components and kinetic energy parameters vary significantly by age and sex. Age and sex trends should be considered in the interpretation of quantitative measures of biventricular flow.Clinical trial registration https://www.clinicaltrials.gov. Unique identifier: NCT03217240.