Left Ventricular Volume-time Curves Research Articles

Machine learning based quantification of ejection and filling parameters by fully automated dynamic measurement of left ventricular volumes from cardiac magnetic resonance images

BackgroundAlthough analysis of cardiac magnetic resonance (CMR) images provides accurate and reproducible measurements of left ventricular (LV) volumes, these measurements are usually not performed throughout the cardiac cycle because of lack of tools that would allow such analysis within a reasonable timeframe. A fully-automated machine-learning (ML) algorithm was recently developed to automatically generate LV volume-time curves. Our aim was to validate ejection and filling parameters calculated from these curves using conventional analysis as a reference. MethodsWe studied 21 patients undergoing clinical CMR examinations. LV volume-time curves were obtained using the ML-based algorithm (Neosoft), and independently using slice-by-slice, frame-by-frame manual tracing of the endocardial boundaries. Ejection and filling parameters derived from these curves were compared between the two techniques. For each parameter, Bland-Altman bias and limits of agreement (LOA) were expressed in percent of the mean measured value. ResultsTime-volume curves were generated using the automated ML analysis within 2.5 ± 0.5 min, considerably faster than the manual analysis (43 ± 14 min per patient, including ~10 slices with 25–32 frames per slice). Time-volume curves were similar between the two techniques in magnitude and shape. Size and function parameters extracted from these curves showed no significant inter-technique differences, reflected by high correlations, small biases (<10%) and mostly reasonably narrow LOA. ConclusionML software for dynamic LV volume measurement allows fast and accurate, fully automated analysis of ejection and filling parameters, compared to manual tracing based analysis. The ability to quickly evaluate time-volume curves is important for a more comprehensive evaluation of the patient's cardiac function.

Influence of Left Atrial Function on Exercise Capacity and Left Ventricular Function in Patients With Heart Failure and Preserved Ejection Fraction.

Although left atrial (LA) dysfunction is common in heart failure with preserved ejection fraction (HFpEF), its functional implications beyond the reflection of left ventricular (LV) pathology are not well understood. The aim of this study was to further characterize LA function in HFpEF patients. We performed cardiac magnetic resonance myocardial feature tracking in 22 patients with HFpEF and 12 patients without HFpEF. LA reservoir strain, LA conduit strain, and LA booster pump strain were quantified. Peak oxygen uptake (VO2max) was determined. Invasive pressure-volume loops were obtained to evaluate LV diastolic properties. LV early filling was determined from LV volume-time curves as derived from cardiac magnetic resonance. LA reservoir and conduit strain were significantly lower in HFpEF (LA reservoir strain, 22±7% versus 29±6%, P=0.04; LA conduit strain, -9±5% versus -15±4%, P<0.01). Patients with HFpEF showed lower oxygen uptake (17±6 versus 29±8 mL/(kg min); P<0.01). Strain measurement for LA conduit function was strongly associated with VO2max (r=0.80; P<0.01). On multivariable regression analysis, LA conduit strain emerged as strongest predictor for VO2max even after inclusion of LV stiffness and relaxation time (β=0.80; P<0.01). LA conduit strain correlated with the volume of early ventricular filling (r=0.67; P<0.01), but not LV stiffness constant β (-0.34; P=0.051) or relaxation constant τ (r=-0.33; P=0.06). Cardiac magnetic resonance myocardial feature tracking-derived conduit strain is significantly impaired in HFpEF and associated with exercise intolerance. Impaired conduit function is associated with impaired early ventricular filling, as potential mechanism leading to impaired oxygen uptake. Our results propose that impaired LA conduit function represents a distinct feature of HFpEF, independent of LV stiffness and relaxation. URL: http://www.clinicaltrials.gov. Unique identifier: NCT02459626.

Non-invasive measurement of volume–time curves in patients with mitral regurgitation and in healthy volunteers, using a new operator-independent screening tool

Left ventricular volume–time curves (VTCs) provide hemodynamic data, and may help clinical decision making. The generation of VTCs using echocardiography, however, is time-consuming and prone to inter-operator variability. In this study, we used a new non-invasive, operator-independent technique, the hemodynamic cardiac profiler (HCP), to generate VTCs. The HCP, which uses a low-intensity, patient-safe, high-frequency applied AC current, and 12 standard ECG electrodes attached on the thorax in a pre-defined pattern, was applied to five young healthy volunteers, five older healthy volunteers, and five patients with severe mitral regurgitation. From the VTCs generated by the HCP, the presence or absence of an isovolumetric contraction phase (ICP) was assessed, as well as the left ventricular ejection time (LVET), time of the pre-ejection period (tPEP), and ratio of the volumes of the early (E) and late (A) diastolic filling (EV/AV ratio), and compared to 2D transthoracic echocardiography (2D TTE) at rest. The reproducibility by two different operators showed good results (RMS = 5.2%). For intra-patient measurement RMS was 2.8%. Both LVET and the EV/AV ratio showed a strong significant correlation between HCP and 2D TTE derived parameters (p < 0.05). For tPEP, the correlation was still weak (p = 0.32). In all five patients with mitral regurgitation, the ICP was absent in the VTC from the HCP, whereas it was present in the 10 healthy volunteers, which is in accordance with pathophysiology. We conclude that the HCP seems to be a method for reproducible VTC generation, and may become a useful early screening tool for cardiac dysfunction in the future.

GW24-e0649 Assessment of left ventricular regional systolic function in patients with hypertrophic cardiomyopathy by real-time three-dimensional echocardiography

ObjectivesThe aim of our study is to assess left ventricular regional systolic function in patients with hypertrophic cardiomyopathy (HCM) using real-time three-dimensional echocardiography (RT-3DE).MethodsRT-3DE was performed in 25 HCM patients...

Assessment of regional left ventricular systolic function in patients with hypertrophic cardiomyopathy by real-time three-dimensional echocardiography

Objective To assess regional left ventricular systolic function in patients with hypertrophic cardiomyopathy (HCM) using real-time three-dimensional echocardiography (RT-3DE).Methods Twenty-five patients with HCM which was asymmetric septal hypertrophy,and twenty healthy subjects were enrolled in the study.The apical four-chamber view of left ventricular was acquired by RT-3DE.The left ventricular volume-time curves were analyzed quantitatively with Tomtec 4D LV-Analysis 3.0,and regional end-diastolic volume and end-systolic volume of left ventricular (rEDV,rESV),the time to minimum systolic volume (rESVT),regional stroke volume (rSV),regional ejection fraction (rEF),regional-global ejection fraction (rgEF) and the parameters of left ventricular dyssynchrony were measured.Results In the HCM group,the values of Tmsv16-Dif,Tmsv16-SD,Tmsv16-Dif％,Tmsv16-SD％ were significantly lower compared with the control group (P ＜ 0.01),and rEDV,rSV,rEF and rgEF in hypertrophic segments were lower than those in non-thickening and mild-thickening segments (P ＜0.05).In the control group,there were no significant difference of those parameters among all segments (P ＞0.05).The values of rEDV,rSV and rgEF in hypertrophic segments decreased in the HCM group (P ＜0.05),at the basal level,rEF in hypertrophic segments decreased,at the apical level,it increased,but the differences at the mid-ventricular level between the two groups were not significant;the values of rEF and rgEF in non-thickening and mild-thickening segments increased (P ＜0.05).Conclusions RT-3DE could sensitively detect left ventricular dyssynchrony and accurately assess regional left ventricular volume and function of different segments in patients with HCM. Key words: Echocardiography, real-time three-dimensional; Cardiomyopathy, hypertrophic; Ventricular function, left

Validation of Real-Time 3d Echocardiography Left Ventricular Volume- Time Curves with Cardiac MRI and Clinical Utilization of Emptying and Filling Rates

Background: 3D echocardiography derived volumetric data can be used to generate left ventricular volume time curves and has the potential to elucidate aspects of contractility, systolic and diastolic function in normal and disease states. We sought to establish the validity and reproducibility of these volume-time curves and apply novel parameters derived from these curves to a clinical population. Methods: Consecutive patients, who underwent cardiac MRI and echocardiography within 12 hours, were used to compare volume-time curves. Inter- and intra observer variability of the 3D echocardiography volume-time curves was assessed. Peak emptying rates, peak filling rates, and peak systolic acceleration were measured in a normal population (normal Ejection Fraction (EF) and no significant valvular disease) and their change with age was evaluated. Results: 16 patients with an average EF of 55% ± 10% underwent cardiac MRI and 3D echocardiography. Therewas no significant difference between the systolic and diastolic slopes of the volume-time curves derived by the two methods with good correlation for both systole (r=0.62, p < 0.0001) and diastole (r=0.43, p=0.0025). In 50 normal patients aged 19-91, peak emptying rate, peak filling rate, and peak systolic acceleration all decreased with age. Conclusion: 3D echocardiography volume-time curves correlate well with the gold standard of cardiac MRI. The novel 3D parameters of peak emptying rate, peak filling rate, and peak systolic acceleration may prove to be helpful in the assessment of systolic and diastolic function and provide insight into ventricular performance.

Left ventricular volume-time curves generated by real-time 3D echocardiography: A new quantitative approach for detecting diastolic dysfunction Ziad Zeidan, Thomas Buck, Joerg Barkhausen, Thomas Bartel, Joerg Debatin, Raimund Erbel. Department of Cardiology, University of Essen, Essen, Geramny, Dept. of Radiology, University of Essen, Essen, Germany

Left ventricular volume-time curves generated by real-time 3D echocardiography: A new quantitative approach for detecting diastolic dysfunction Ziad Zeidan, Thomas Buck, Joerg Barkhausen, Thomas Bartel, Joerg Debatin, Raimund Erbel. Department of Cardiology, University of Essen, Essen, Geramny, Dept. of Radiology, University of Essen, Essen, Germany