Left Ventricular Flow Research Articles

Fluid structure computational model of simulating mitral valve motion in a contracting left ventricle

Background:Fluid structure interaction simulations h hold promise in studying normal and abnormal cardiac function, including the effect of fluid dynamics on mitral valve (MV) leaflet motion. The goal of this study was to develop a 3D fluid structure interaction computational model to simulate bileaflet MV when interacting with blood motion in left ventricle (LV). Methods:The model consists of ideal geometric-shaped MV leaflets and the LV, with MV dimensions based on human anatomical measurements. An experimentally-based hyperelastic isotropic material was used to model the mechanical behaviour of the MV leaflets, with chordae tendineae and papillary muscle tips also incorporated. LV myocardial tissue was prescribed using a transverse isotropic hyperelastic formulation. Incompressible Navier–Stokes fluid formulations were used to govern the blood motion, and the Arbitrary Lagrangian Eulerian (ALE) method was employed to determine the mesh deformation of the fluid and solid domains due to trans-valvular pressure on MV boundaries and the resulting leaflet movement. Results:The LV–MV generic model was able to reproduce physiological MV leaflet opening and closing profiles resulting from the time-varying atrial and ventricular pressures, as well as simulating normal and prolapsed MV states. Additionally, the model was able to simulate blood flow patterns after insertion of a prosthetic MV with and without left ventricular outflow tract flow obstruction. In the MV–LV normal model, the regurgitant blood flow fraction was 10.1 %, with no abnormality in cardiac function according to the mitral regurgitation severity grades reported by the American Society of Echocardiography. Conclusion:Our simulation approach provides insights into intraventricular fluid dynamics in a contracting LV with normal and prolapsed MV function, as well as aiding in the understanding of possible complications after transcatheter MV implantation prior to clinical trials.

Effect Evaluation of Norepinephrine on Cardiac Function in Patients with Sepsis by Cardiac Ultrasound Imaging.

In order to investigate the therapeutic effect of norepinephrine on patients with sepsis and the effect of echocardiography on the diagnosis of cardiac function in patients with sepsis, 86 patients with sepsis were selected as research objects and randomly divided into two groups. Patients in the control group (N = 43 cases) received conventional treatment (1~15 μg/kg∗min dopamine), and those in the experimental group (N = 43 cases) received conventional treatment+norepinephrine therapy (0.05~0.5 μg∗kg−1/min). The clinical efficacy, cardiac ultrasonography results, and hemodynamic indexes of patients between the two groups were analyzed and compared. The results showed that the total effective rate of treatment in the experimental group (97.7%) was significantly higher than that in the control group (81.4%) (P < 0.05). The maximum, minimum, and average values of mitral valve E peak flow velocity (VEpeak) and left ventricular outflow tract peak flow velocity (Vpeak), respiratory variability of mitral valve E peak flow velocity (ΔVEpeak), and respiratory variability of peak flow velocity (ΔVpeak) were all significantly greater than those of the control group (P < 0.05). The area under the receiver operating characteristic curve (AUC) of ΔVEpeak and ΔVpeak for predicting positive volume response in patients with sepsis was 0.934 and 0.913, respectively; the sensitivity was 0.828 and 0.827; the specificity was 0.936 and 0.893; and the Youden indices were 0.765 and 0.712, respectively. In short, norepinephrine had a high total response rate in patients with sepsis, and echocardiography can well evaluate the effect of norepinephrine on cardiac function in patients with sepsis, which is worthy of further promotion.

Design and execution of a verification, validation, and uncertainty quantification plan for a numerical model of left ventricular flow after LVAD implantation.

Left ventricular assist devices (LVADs) are implantable pumps that act as a life support therapy for patients with severe heart failure. Despite improving the survival rate, LVAD therapy can carry major complications. Particularly, the flow distortion introduced by the LVAD in the left ventricle (LV) may induce thrombus formation. While previous works have used numerical models to study the impact of multiple variables in the intra-LV stagnation regions, a comprehensive validation analysis has never been executed. The main goal of this work is to present a model of the LV-LVAD system and to design and follow a verification, validation and uncertainty quantification (VVUQ) plan based on the ASME V&V40 and V&V20 standards to ensure credible predictions. The experiment used to validate the simulation is the SDSU cardiac simulator, a bench mock-up of the cardiovascular system that allows mimicking multiple operation conditions for the heart-LVAD system. The numerical model is based on Alya, the BSC's in-house platform for numerical modelling. Alya solves the Navier-Stokes equation with an Arbitrary Lagrangian-Eulerian (ALE) formulation in a deformable ventricle and includes pressure-driven valves, a 0D Windkessel model for the arterial output and a LVAD boundary condition modeled through a dynamic pressure-flow performance curve. The designed VVUQ plan involves: (a) a risk analysis and the associated credibility goals; (b) a verification stage to ensure correctness in the numerical solution procedure; (c) a sensitivity analysis to quantify the impact of the inputs on the four quantities of interest (QoIs) (average aortic root flow [Formula: see text], maximum aortic root flow [Formula: see text], average LVAD flow [Formula: see text], and maximum LVAD flow [Formula: see text]); (d) an uncertainty quantification using six validation experiments that include extreme operating conditions. Numerical code verification tests ensured correctness of the solution procedure and numerical calculation verification showed a grid convergence index (GCI)95% <3.3%. The total Sobol indices obtained during the sensitivity analysis demonstrated that the ejection fraction, the heart rate, and the pump performance curve coefficients are the most impactful inputs for the analysed QoIs. The Minkowski norm is used as validation metric for the uncertainty quantification. It shows that the midpoint cases have more accurate results when compared to the extreme cases. The total computational cost of the simulations was above 100 [core-years] executed in around three weeks time span in Marenostrum IV supercomputer. This work details a novel numerical model for the LV-LVAD system, that is supported by the design and execution of a VVUQ plan created following recognised international standards. We present a methodology demonstrating that stringent VVUQ according to ASME standards is feasible but computationally expensive.

CARD26: Effects of the Artificial Pulse of the HeartMate 3 on Left Ventricular Flow Patterns

Purpose of study: In order to reduce the risk of thrombotic events in left ventricular assist device patients, the HeartMate 3 is equipped with an artificial pulse (AP) setting. However, experimental results concerning the AP’s impact on left ventricular (LV) flow patterns and timing within the cardiac contraction are limited. This study aims to analyze LV flow patterns occurring during and after the AP, which is synchronized to the simulated cardiac function inside the mock loop setup. Methods: The in vitro measurements were triggered using a system capable of detecting AP timing and were performed for selected timings within the cardiac cycle. A pulsatile cardiovascular mock loop was developed with a simplified LV model and the flow patterns were imaged via Particle Image Velocimetry. The measurements were performed with stroke volumes of 0ml, 38ml, 49ml, and 57ml, with pump speeds configured to achieve 80mmHg mean aortic pressure and a total cardiac output of 5l/min for all settings. Parameters such as kinetic energy (KE) were computed in specific regions of interest, especially in the LV apex, as they indicate LV washout. Results: The overall influence of the AP on the intraventricular flow appears small (2.5% increase in KEmean for entire flow field), however short durations of large KE increases were observed in the LV apex with the AP turned on (KE mean: +4%; KEpeak: +24%), showing a dependence on the timing of the AP (KEpeak increased by up to 39% for specific timings). This increase can be observed when a counter-clockwise vortex ring of the mitral jet travelled further towards the apex, which was seen for specific timings of the AP. Vortices arising next to the valves could also improve washout there. Conclusion: While the AP produced only minor effects in the overall flow fields, synchronization of the AP with the cardiac cycle could potentially lead to increased LV washout, thus leading to better clinical outcomes.

CARD21: In Vitro Investigation Of The Timing Of The LVAD Pulsatility Event On Intraventricular Hemodynamics

Background: To reduce in-pump thrombosis and potentially improve left ventricular (LV) washout, pulsatility events (i.e., periodic LVAD speed modulation) have been introduced in 3rd generation LVADs. However, this pseudo-pulsatility of the centrifugal continuous flow pumps is not synchronized with native LV residual contractility. This study investigates the effect of timing of pulsatility events, with respect to LV pressure variations along the cardiac cycle, on intraventricular hemodynamics. Methods: Time-resolved stereo particle image velocimetry measurements were performed in a patient-derived quasirigid LV silicon model implanted with an LVAD. The residual LV contractility was modelled as a periodic variation in intraventricular pressure (IVP). Velocity fields in two orthogonal planes were measured for 7.5 cardiac cycles (including 3 occurrences of the pulsatility events, which happen every two seconds), for 3 LVAD speeds and 4 different synchronicities of pulsatility: at maximum/ minimum IVP and during increasing/decreasing IVP. Instantaneous measurements of the flowrate through the LVAD, with a time-resolution of 1 ms, were collected during the entire experiment. Ventricle stagnation index (VSI) was computed for each measurement plane and all experimental conditions studied. Results: Despite maintaining a constant average flowrate, the synchronicity of the LVAD pulsatility with the oscillatory IVP strongly influenced the flow rate waveforms, especially the peak and minimum instantaneous flow rates. A strong effect of the timing of pulsatility was also observed on intraventricular hemodynamics: pulsatility events taking place during decreasing IVP (diastole) resulted in higher VSI than other timing of pulsatility. Overall, these high resolution, instantaneous measurements of LVAD flow rate and pressure also highlighted the complex interrelations between LVAD speed, peripheral resistance, IVP and flow rate. Conclusion: This in vitro study elucidates the effect of LVAD pulsatility event synchronicity with the cardiac cycle on flowrate and LV flow patterns.

Effect of 3D-printed hearts used in left ventricular outflow tract obstruction: a multicenter study

ObjectiveThe purpose of this research was to explore the application value of a three-dimensional (3D)-printed heart in surgery for left ventricular outflow tract (LVOT) obstruction.MethodsFrom August 2019 to October 2021, 46 patients with LVOT obstruction underwent surgical treatment at our institution. According to the treatment method, 22 and 24 patients were allocated to the experimental and control groups, respectively. In the experimental group, each patient’s 3D-printed heart model was used for simulated preoperative surgery, and then the Morrow operation was performed. In the control group, only the Morrow operation was performed, without simulated preoperative surgery using a 3D-printed heart model. The intraoperative and postoperative data of patients in the two groups were recorded, and the clinical data of patients were compared between the two groups.ResultsThe operation time, cardiopulmonary bypass time, intraoperative blood loss, hospitalization time, LVOT pressure difference (LVP), postoperative interventricular septal thickness (IST), aortic regurgitation (AR), systolic anterior motion (SAM), and postoperative left ventricular flow velocity (LVFV) were significantly lower in the experimental group than in the control group (P < 0.05). The inner diameter of the left ventricular outflow tract (IDLV) was larger in the experimental group than in the control group (P < 0.05). There was no significant difference in the postoperative ejection fraction, atrioventricular block rate or complication rate between the two groups (P > 0.05).ConclusionA 3D-printed heart model for simulated surgery in vitro is conducive to formulating a more reasonable surgical plan and reducing the trauma and duration of surgery, thereby promoting the recovery and maintenance of the heart.

Highlights From the Circulation Family of Journals

Highlights From the <i>Circulation</i> Family of Journals

Effects of MitraClip Therapy on Mitral Flow Patterns and Vortex Formation: An In Vitro Study.

MitraClip transcatheter edge-to-edge repair is used to treat mitral regurgitation (MR). While MR is reduced, diastolic left ventricular flows are altered. An in vitro left heart simulator was used to assess a porcine mitral valve in the native, MR, and MR plus MitraClip cases. Velocity, vorticity, and Reynolds shear stress (RSS) were quantified by particle image velocimetry. Peak velocity increased from 1.20 m/s for native to 1.30 m/s with MR. With MitraClip, two divergent jets of 1.18 and 0.61 m/s emerged. Higher vorticity was observed with MR than native and lessened with MitraClip. MitraClip resulted in shear layer formation and downstream vortex formation. Native RSS decreased from 33 Pa in acceleration to 29 Pa at peak flow, then increased to 31 Pa with deceleration. MR RSS increased from 27 Pa in acceleration to 40 Pa at peak flow to 59 Pa during deceleration. MitraClip RSS increased from 79 Pa in acceleration to 162 Pa during peak flow, then decreased to 45 Pa during deceleration. After MitraClip, two divergent jets of reduced velocity emerged, accompanied by shear layers and recirculation. Chaotic flow developed, resulting in elevated RSS magnitude and coverage. Findings help understand consequences of MitraClip on left ventricular flow dynamics.

Effect of Coronary Arterial Dominance Post Primary Percutaneous Coronary Artery Intervention (PCI) during Hospital Stay and at 3-Month Follow-up

Background: Coronary vessel dominance, defined by the coronary artery that supplies the posterior descending artery (PDA) and posterolateral branches, influences the relative contribution of the different coronary arteries to the total left ventricular blood flow. This work aimed to evaluate the prognostic value of coronary arterial dominance post primary PCI, during hospital stay and at 3-month follow-up, which include; cardiac mortality, heart failure, non-fatal myocardial infarction, re-vascularization, stroke/TIA and re-admission for ACS. Methods: This prospective observational study included 100 patients a with STEMI who underwent successful primary percutaneous coronary intervention with TIMI III flow and without procedural complications. Patients were divided into 3 groups according to coronary dominance: Right coronary dominant group (RCD), left coronary dominant group (LCD) and balanced coronary dominant group (BCD). All patients were subjected to transthoracic echocardiogram and coronary angiography and Primary percutaneous coronary intervention. Results: Ticagrelor and clopidogrel during hospital stay and on hospital discharge were significantly used more with RCA group than LCX group and LCX &amp; RCA group (P=0.021, 0.012), (P=0.018, 0.014), respectively. GPIIB/IIIA was significantly more used during hospital stay with RCA group than LCX group and LCX &amp; RCA group(P=0.014). Nitrates was significantly used more on hospital discharge with RCA group than LCX group and LCX &amp; RCA group (P&lt;0.001). Conclusions: Coronary arterial domi¬nance showed significant prognostic value in cases of myocardial Infarction after PCI, heart failure in LCX cases and in revascularization, heart failure, and stroke/TIA cases in RCA. Further, readmission for ACS was the most common outcome in all groups after 3-months follow-up.

Electrocardiography Diagnostic Performance in the Assessment of Significant Coronary Artery Disease and its Anatomical site in Comparison with Coronary Angiography among Nigerians: A Pilot Study

Background: Coronary vessel dominance, defined by the coronary artery that supplies the posterior descending artery (PDA) and posterolateral branches, influences the relative contribution of the different coronary arteries to the total left ventricular blood flow. This work aimed to evaluate the prognostic value of coronary arterial dominance post primary PCI, during hospital stay and at 3-month follow-up, which include; cardiac mortality, heart failure, non-fatal myocardial infarction, re-vascularization, stroke/TIA and re-admission for ACS. Methods: This prospective observational study included 100 patients a with STEMI who underwent successful primary percutaneous coronary intervention with TIMI III flow and without procedural complications. Patients were divided into 3 groups according to coronary dominance: Right coronary dominant group (RCD), left coronary dominant group (LCD) and balanced coronary dominant group (BCD). All patients were subjected to transthoracic echocardiogram and coronary angiography and Primary percutaneous coronary intervention. Results: Ticagrelor and clopidogrel during hospital stay and on hospital discharge were significantly used more with RCA group than LCX group and LCX &amp; RCA group (P=0.021, 0.012), (P=0.018, 0.014), respectively. GPIIB/IIIA was significantly more used during hospital stay with RCA group than LCX group and LCX &amp; RCA group(P=0.014). Nitrates was significantly used more on hospital discharge with RCA group than LCX group and LCX &amp; RCA group (P&lt;0.001). Conclusions: Coronary arterial domi¬nance showed significant prognostic value in cases of myocardial Infarction after PCI, heart failure in LCX cases and in revascularization, heart failure, and stroke/TIA cases in RCA. Further, readmission for ACS was the most common outcome in all groups after 3-months follow-up.

Classification and Recognition of Doppler Ultrasound Images of Patients with Atrial Fibrillation under Machine Learning

This study was aimed to explore the value of the twin neural network model in the classification and recognition of cardiac ultrasound images of patients with atrial fibrillation. 80 patients with cardiac atrial fibrillation were selected and randomly divided into experimental group (40 cases) and control group (40 cases). The twin neural network (TNN) model was combined with traditional ultrasound, Doppler spectrum, tissue velocity, and strain imaging technology to obtain the patient’s cardiac structure parameters and analyze and compare related indicators. The results showed that the total atrial emptying fraction (TA-EF value) of the experimental group was 53.08%, which was significantly lower than that of the control group ( P &lt; 0.05 ). There were no significant differences in left atrial diameter (LAD), left ventricular end-diastolic diameter (LVEDD), left atrial maximum volume (LAVmax), and left ventricular ejection fraction (LVEF) between the two groups. In the experimental group, the average peak velocity of mitral valve annulus (Em) was 8.49 cm/s, the peak velocity of lateral wall systole (Vs) was 6.82 cm/s, and the propagation velocity of left ventricular blood flow (Vp) was 51.2 cm/s, which were significantly reduced ( P &lt; 0.05 ). The average values of peak strains in the middle and upper left atrium of the experimental group were significantly lower than those of the control group ( P &lt; 0.05 ). It can be concluded that the combined use of the TNN model can more accurately and quickly classify and recognize ultrasound images.

Shengmai Yin alleviated plaque vulnerability and ischemic myocardial damage in diesel exhaust particle-aggravated atherosclerosis with myocardial ischemia

Exposure to diesel exhaust particles (DEP) increases the risk of ischemic heart disease, especially heart attacks and ischemic/thrombotic strokes. Shengmai Yin (SMY) is a traditional Chinese medicine used to treat coronary heart disease. The aim of this study was to determine the protective role of SMY and the mechanism by which SMY affects DEP-induced cardiovascular injury. This study is expected to provide the basis for the development of an adaptive signature of SMY in the prevention of atherosclerotic cardiovascular disease and premature death from global air pollution exposure. We developed animal models of myocardial ischemia and atherosclerosis (AS) in response to DEP exposure. After SMY treatment, serum lipids returned to normal. Aortic plaque area and MMP9 expression were significantly reduced and collagen fiber expression increased after SMY treatment compared to DEP exposure alone. Thus, the risk of plaque formation and vulnerability is reduced. In addition, SMY improved left ventricular structure, morphology, function, blood flow, infarct area, myocardial damage, and ROS accumulation to varying degrees in ApoE-/- mice. These results indicate that the use of SMY is effective, to varying degrees, for the treatment of dyslipidemia, atherosclerosis, myocardial ischemia, and oxidative stress in ApoE-/- mice. SMY has a potential protective effect in DEP-aggravated AS in people with myocardial ischemia.

Left ventricular four-dimensional blood flow distribution, energetics, and vorticity in chronic myocardial infarction patients with/without left ventricular thrombus

BackgroundLeft ventricular thrombus (LVT) formation is a frequent and serious complication of myocardial infarction (MI). How global LV flow characteristics are related to this phenomenon is yet uncertain. In this study, we investigated LV flow differences using 4D flow cardiovascular magnetic resonance (CMR) between chronic MI patients with LVT [MI-LVT(+)] and without LVT [MI-LVT(-)], and healthy controls. MethodsIn this prospective cohort study, the 4D flow CMR data were acquired in 19 chronic MI patients (MI-LVT(+), n = 9 and MI-LVT(-), n = 10) and 9 age-matched controls. All included subjects were in sinus rhythm. The following LV flow parameters were obtained: LV flow components (direct, retained, delayed, residual), mean and peak kinetic energy (KE) values (indexed to instantaneous LV volume), mean and peak vorticity values, and diastolic vortex ring properties (position, orientation, shape). ResultsThe MI patients demonstrated a significantly larger amount of delayed and residual flow, and a smaller amount of direct flow compared to controls (p = 0.02, p = 0.03, and p < 0.001, respectively). The MI-LVT(+) patients demonstrated numerically increased residual flow and reduced retained and direct flow in comparison to MI-LVT(-) patients. Systolic mean and peak LV blood flow KE values were significantly lower in MI patients compared to controls (p = 0.04, p = 0.03, respectively). Overall, the mean and peak LV vorticity values were significantly lower in MI patients compared to controls. The mean and peak systolic vorticity at the basal level were significantly higher in MI-LVT(+) than in MI-LVT(-) patients (p < 0.01, for both). The vortex ring core during E-wave in MI-LVT(+) group was located in a less tilted orientation to the LV compared to MI-LVT(-) group (p < 0.01). ConclusionsChronic MI patients with LVT express a different distribution of LV flow components, irregular vorticity vector fields, and altered diastolic vortex ring geometric properties as assessed by 4D flow CMR. Larger prospective studies are warranted to further evaluate the significance of these initial observations.

Relationship Between Myocardial Perfusion Imaging Abnormalities on Positron Emission Tomography and Anginal Symptoms, Functional Status, and Quality of Life.

Myocardial perfusion imaging (MPI) identifies abnormalities that occur early in the ischemic cascade leading to angina. Our aim was to study the association between ischemic measures on positron emission tomography MPI and patients' health status; their symptoms, function, and quality of life. Health status was collected using the Seattle Angina Questionnaire (SAQ-7, 0-100, higher=better) and Rose Dyspnea Score (RDS) on 1515 outpatients with known or suspected coronary artery disease presenting for clinically indicated pharmacological 82Rb positron emission tomography MPI from July 2018 to July 2019. Adjusted multivariable ordinal regression models were used to assess the association between MPI findings of ischemia and the SAQ physical limitation, angina frequency, quality of life, summary score, and the RDS. The mean SAQ and RDS scores of the cohort (mean age 71.7 years, 55% male, 37.6% prior myocardial infarction or revascularization) were 73.8±28.6 (physical limitation), 87.4±21.7 (angina frequency), 79.0±26.1 (quality of life), 81.3±19.0 (summary score), and 2±2 (RDS). No perfusion, flow or function abnormalities were significantly associated with SAQ angina frequency scores. Low left ventricular ejection fraction reserve (≤0%), low global and regional myocardial blood flow reserve (<2) were independently associated with worse SAQ Physical Limitation score, SAQ summary score, and RDS (30% to 57% greater odds; all P≤0.01), but reversible perfusion defects were not. Impaired augmentation of left ventricular ejection fraction and myocardial blood flow with stress is associated with significant angina-associated functional limitation, health status, and dyspnea in patients who underwent positron emission tomography MPI, but not the frequency of their angina. Future studies should evaluate whether therapies that improve stress-induced abnormalities in systolic function and myocardial flow may improve patients' health status.

Co-simulation of hypertensive left ventricle based on computational fluid dynamics and a closed-loop network model

ObjectiveHypertension is one of the most common chronic and cardiovascular diseases, with the largest number of deaths. According to clinical experience, long-term hypertension will cause cardiac hypertrophy and other complications, and heart structure remodeling will significantly change the energy characteristics of the heart chambers, and impair heart function. Research shows that, early hypertension can be diagnosed by the blood flow and energy loss in the left ventricle. Therefore, it is important to choose an appropriate method to simulate and predict the flow domain of this ventricle. MethodsThis study took the left ventricular flow field of patients with hypertensive myocardial hypertrophy as the research object, used MATLAB-SIMULINK to establish a closed-loop network cardiovascular model, provided flow boundary conditions for the computational fluid dynamics (CFD) numerical simulation method, and, finally, completed a co-simulation. ResultsThis article compared the degree of agreement between the energy loss in different phases of the heart cavity and clinical experimental data and summarized the characteristics of the flow field in patients with hypertensive myocardial hypertrophy. The analysis of three simulation groups (control group, non-left ventricular hypertrophy group, and left ventricular hypertrophy [LVH] group) showed that the vortices in the LVH group were irregular and not fully developed, accompanied by significant energy loss. ConclusionThe simulation method used in this study is basically consistent with the clinical data. Myocardial hypertrophy has a significant influence on the blood flow of the left ventricle. Changes in the blood flow make the left ventricular vortex distribution abnormal during the rapid systole and rapid ejection periods, leading to a series of dangerous factors, including increased energy loss and a low cardiac ejection fraction.

Development of a dedicated 3D printed myocardial perfusion phantom: proof-of-concept in dynamic SPECT

We aim to facilitate phantom-based (ground truth) evaluation of dynamic, quantitative myocardial perfusion imaging (MPI) applications. Current MPI phantoms are static representations or lack clinical hard- and software evaluation capabilities. This proof-of-concept study demonstrates the design, realisation and testing of a dedicated cardiac flow phantom. The 3D printed phantom mimics flow through a left ventricular cavity (LVC) and three myocardial segments. In the accompanying fluid circuit, tap water is pumped through the LVC and thereafter partially directed to the segments using adjustable resistances. Regulation hereof mimics perfusion deficit, whereby flow sensors serve as reference standard. Seven phantom measurements were performed while varying injected activity of 99mTc-tetrofosmin (330–550 MBq), cardiac output (1.5–3.0 L/min) and myocardial segmental flows (50–150 mL/min). Image data from dynamic single photon emission computed tomography was analysed with clinical software. Derived time activity curves were reproducible, showing logical trends regarding selected input variables. A promising correlation was found between software computed myocardial flows and its reference (rho= − 0.98; p = 0.003). This proof-of-concept paper demonstrates we have successfully measured first-pass LV flow and myocardial perfusion in SPECT-MPI using a novel, dedicated, myocardial perfusion phantom.Graphical abstractThis proof-of-concept study focuses on the development of a novel, dedicated myocardial perfusion phantom, ultimately aiming to contribute to the evaluation of quantitative myocardial perfusion imaging applications.

Influence of Light Intensity exercise During Pregnancy on Fetal Echocardiographic and Maternal Cardiovascular Measures

Background: Although moderate intensity maternal exercise is recommended during pregnancy, most women do not achieve this level. Objective: This study aimed to determine the effects of supervised maternal light-intensity exercise on fetal cardiovascular measures in the 3rd trimester. Materials and Methods: We compared women participating in light-intensity (LI) stretching/breathing or no exercise (CON) across 24+ weeks of pregnancy Women with singleton pregnancies (&lt;16 weeks), between 18-40 years, 18.5-34.99 kg/m2 BMI, and having no chronic health conditions were eligible. LI did 150 minutes light-intensity weekly exercise; CON did normal daily activities, but no exercise. Maternal measures included resting heart rate (HR) and blood pressure (BP). Fetal measures included estimated fetal weight (EFW), ponderal index (PI), HR, along with right and left ventricular measures (e.g., stroke volume, cardiac output, ejection fraction) at 36 weeks’ gestation. T-tests compared differences between groups; partial spearman rank correlations and regressions were performed to find relationships and predict fetal echocardiographic outcomes, controlling for fetal activity state. Results: Of 50 pregnant women (n=26 in LI, n=24 in CON), we found maternal exercise intensity influences fetal left ventricular heart flow, while maternal exercise duration influences fetal right ventricular outcomes. There were no differences (p&gt;0.05) in fetal cardiac anatomical measures. Lastly, light intensity exercise and duration of exercise lower maternal blood pressure in late pregnancy. Conclusions:Light-intensity exercise is associated with improved fetal cardiac measures. Women benefit from light intensity exercise during pregnancy. Cardiovascular benefits from exercise for mother and child are dose dependent.

Right ventricular energetic biomarkers from 4D Flow CMR are associated with exertional capacity in pulmonary arterial hypertension

BackgroundCardiovascular magnetic resonance (CMR) offers comprehensive right ventricular (RV) evaluation in pulmonary arterial hypertension (PAH). Emerging four-dimensional (4D) flow CMR allows visualization and quantification of intracardiac flow components and calculation of phasic blood kinetic energy (KE) parameters but it is unknown whether these parameters are associated with cardiopulmonary exercise test (CPET)-assessed exercise capacity, which is a surrogate measure of survival in PAH. We compared 4D flow CMR parameters in PAH with healthy controls, and investigated the association of these parameters with RV remodelling, RV functional and CPET outcomes.MethodsPAH patients and healthy controls from two centers were prospectively enrolled to undergo on-site cine and 4D flow CMR, and CPET within one week. RV remodelling index was calculated as the ratio of RV to left ventricular (LV) end-diastolic volumes (EDV). Phasic (peak systolic, average systolic, and peak E-wave) LV and RV blood flow KE indexed to EDV (KEIEDV) and ventricular LV and RV flow components (direct flow, retained inflow, delayed ejection flow, and residual volume) were calculated. Oxygen uptake (VO2), carbon dioxide production (VCO2) and minute ventilation (VE) were measured and recorded.Results45 PAH patients (46 ± 11 years; 7 M) and 51 healthy subjects (46 ± 14 years; 17 M) with no significant differences in age and gender were analyzed. Compared with healthy controls, PAH had significantly lower median RV direct flow, RV delayed ejection flow, RV peak E-wave KEIEDV, peak VO2, and percentage (%) predicted peak VO2, while significantly higher median RV residual volume and VE/VCO2 slope. RV direct flow and RV residual volume were significantly associated with RV remodelling, function, peak VO2, % predicted peak VO2 and VE/VCO2 slope (all P < 0.01). Multiple linear regression analyses showed RV direct flow to be an independent marker of RV function, remodelling and exercise capacity.ConclusionIn this 4D flow CMR and CPET study, RV direct flow provided incremental value over RVEF for discriminating adverse RV remodelling, impaired exercise capacity, and PAH with intermediate and high risk based on risk score. These data suggest that CMR with 4D flow CMR can provide comprehensive assessment of PAH severity, and may be used to monitor disease progression and therapeutic response.Trial registration number: https://www.clinicaltrials.gov. Unique identifier: NCT03217240.

Longitudinal Changes in Left Ventricular Blood Flow Kinetic Energy After Myocardial Infarction: Predictive Relevance for Cardiac Remodeling.

Four-dimensional (4D) flow cardiac magnetic resonance (cardiac MR) imaging provides quantification of intracavity left ventricular (LV) flow kinetic energy (KE) parameters in three dimensions. ST-elevation myocardial infarction (STEMI) patients have been shown to have altered intracardiac blood flow compared to controls; however, how 4D flow parameters change over time has not been explored previously. Measure longitudinal changes in intraventricular flow post-STEMI and ascertain its predictive relevance of long-term cardiac remodeling. Prospective. Thirty-five STEMI patients (M:F = 26:9, aged 56 ± 9 years). A 3 T/3D EPI-based, fast field echo (FFE) free-breathing 4D-flow sequence with retrospective cardiac gating. Serial imaging at 3-7 days (V1), 3-months (V2), and 12-months (V3) post-STEMI, including the following protocol: functional imaging for measuring volumes and 4D-flow for calculating parameters including systolic and peakE-wave LVKE, normalized to end-diastolic volume (iEDV) and stroke volume (iSV). Data were analyzed by H.B. (3 years experience). Patients were categorized into two groups: preserved ejection fraction (pEF, if EF > 50%) and reduced EF (rEF, if EF < 50%). Independent sample t-tests were used to detect the statistical significance between any two cohorts. P < 0.05 was considered statistically significant. Across the cohort, systolic KEisv was highest at V1 (28.0 ± 4.4μJ/mL). Patients with rEF retained significantly higher systolic KEisv than patients with pEF at V2 (18.2 ± 3.4μJ/mL vs. 6.9 ± 0.6μJ/mL, P < 0.001) and V3 (21.6 ± 5.1μJ/mL vs. 7.4 ± 0.9μJ/mL, P < 0.001). Patients with pEF had significantly higher peakE-wave KEiEDV than rEF patients throughout the study (V1: 25.4 ± 11.6μJ/mL vs. 18.1 ± 9.9μJ/mL, P < 0.03, V2: 24.0 ± 10.2μJ/mL vs. 17.2 ± 12.2μJ/mL, P < 0.05, V3: 27.7 ± 14.8μJ/mL vs. 15.8 ± 7.6μJ/mL, P < 0.04). Systolic KE increased acutely following MI; in patients with pEF, this decreased over 12months, while patients with rEF, this remained raised. Compared to patients with pEF, persistently lower peakE-wave KE in rEF patients is suggestive of early and fixed impairment in diastolic function. 1 TECHNICAL EFFICACY: Stage 3.

Evaluation of intraventricular flow by multimodality imaging: a review and meta-analysis

BackgroundThe aim of this systematic review was to evaluate current inter-modality agreement of noninvasive clinical intraventricular flow (IVF) assessment with 3 emerging imaging modalities: echocardiographic particle image velocimetry (EPIV), vector flow mapping (VFM), and 4-dimensional flow cardiovascular magnetic resonance imaging (4D flow CMR).MethodsWe performed a systematic literature review in the databases EMBASE, Medline OVID and Cochrane Central for identification of studies evaluating left ventricular (LV) flow patterns using one of these flow visualization modalities. Of the 2224 initially retrieved records, 10 EPIV, 23 VFM, and 25 4D flow CMR studies were included in the final analysis.ResultsVortex parameters were more extensively studied with EPIV, while LV energetics and LV transport mechanics were mainly studied with 4D flow CMR, and LV energy loss and vortex circulation were implemented by VFM studies. Pooled normative values are provided for these parameters. The meta- analysis for the values of two vortex morphology parameters, vortex length and vortex depth, failed to reveal a significant change between heart failure patients and healthy controls.ConclusionAgreement between the different modalities studying intraventricular flow is low and different methods of measurement and reporting were used among studies. A multimodality framework with a standardized set of flow parameters is necessary for implementation of noninvasive flow visualization in daily clinical practice. The full potential of noninvasive flow visualization in addition to diagnostics could also include guiding medical or interventional treatment.