Regional Myocardial Velocities Research Articles

Complementary Value of Tissue Doppler Imaging in Dobutamine Stress Echocardiography: A Prospective Cohort Study

Introduction: In patients with Coronary Artery Diseases (CAD), the presence of viable myocardium predicts the recovery of Left Ventricular (LV) systolic function after revascularisation. The identification of myocardial viability during dobutamine stress echocardiography is subjective and with observer bias. Tissue Doppler Imaging (TDI) echocardiography has opened new possibilities for non-invasive quantification of myocardial function by directly interrogating myocardial velocity with high temporal and spatial resolution. Aim: To determine the baseline regional myocardial and mitral annular Maximum Systolic Velocities (MSV) in patients with LV dysfunction and to compare the MSV values in viable and nonviable myocardium. Materials and Methods: In this prospective Cohort study, TDI of regional and annular LV myocardial velocities was performed at the baseline (at rest) in 352 patients with CAD and LV dysfunction who were referred for Dobutamine stress Echocardiography. Viability assessment by 2 Dimensional (2D) methods was done simultaneously using routine Dobutamine stress protocol. Patients were grouped in two groups based on the presence or absence of viability with 2D stress echocardiography. TDI velocities were compared in the two groups of patients with and without myocardial viability. Measurements of regional wall thickness, Ejection Fraction(EF) and Wall Motion Score Index (WMSI) were done to assess the regional and global LV function in these patients. Those patients who underwent revascularisation were subsequently assessed for functional recovery by 2D and TDI echocardiography before discharge from the hospital. Analyses were conducted using Statistical Package for Social Sciences(SPSS) version 16.0. Results: Among 352 patients studied (124 females and 228 males), mean age 58 years (range 36 to 75 years). A total of 243 patients (69%) with viable myocardium as per 2D echocardiography had higher cut-off Baseline Regional Maximum Systolic Velocity (BRMSV) >0.03 m/s and baseline mitral annular systolic velocity >0.06 m/s with high sensitivity and specificity compared to patients with severe contractile dysfunction and non-viable myocardium. Conclusion: Tissue doppler parameters like regional myocardial systolic and mitral annular velocities have shown significantly higher cut-off values in those patients with ischaemic and viable myocardium compared to non-viable myocardium.

Automated segmentation of biventricular contours in tissue phase mapping using deep learning.

Tissue phase mapping (TPM) is an MRI technique for quantification of regional biventricular myocardial velocities. Despite its potential, clinical use is limited due to the requisite labor-intensive manual segmentation of cardiac contours for all time frames. The purpose of this study was to develop a deep learning (DL) network for automated segmentation of TPM images, without significant loss in segmentation and myocardial velocity quantification accuracy compared with manual segmentation. We implemented a multi-channel 3D (three dimensional; 2D + time) dense U-Net that trained on magnitude and phase images and combined cross-entropy, Dice, and Hausdorff distance loss terms to improve the segmentation accuracy and suppress unnatural boundaries. The dense U-Net was trained and tested with 150 multi-slice, multi-phase TPM scans (114 scans for training, 36 for testing) from 99 heart transplant patients (44 females, 1-4 scans/patient), where the magnitude and velocity-encoded (Vx , Vy , Vz ) images were used as input and the corresponding manual segmentation masks were used as reference. The accuracy of DL segmentation was evaluated using quantitative metrics (Dice scores, Hausdorff distance) and linear regression and Bland-Altman analyses on the resulting peak radial and longitudinal velocities (Vr and Vz ). The mean segmentation time was about 2 h per patient for manual and 1.9 ± 0.3 s for DL. Our network produced good accuracy (median Dice = 0.85 for left ventricle (LV), 0.64 for right ventricle (RV), Hausdorff distance = 3.17 pixels) compared with manual segmentation. Peak Vr and Vz measured from manual and DL segmentations were strongly correlated (R≥ 0.88) and in good agreement with manual analysis (mean difference and limits of agreement for Vz and Vr were -0.05 ± 0.98 cm/s and -0.06 ± 1.18 cm/s for LV, and -0.21 ± 2.33 cm/s and 0.46 ± 4.00 cm/s for RV, respectively). The proposed multi-channel 3D dense U-Net was capable of reducing the segmentation time by 3,600-fold, without significant loss in accuracy in tissue velocity measurements.

Poorer Exercise Accommodation of Regional Systolic Myocardial Motion after Spironolactone Treatment in Heart Failure Patients with Preserved Ejection Fraction and Ventricular Dyssynchrony.

Patients with heart failure and preserved ejection fraction (HFpEF) are known to have reduced systolic myocardial velocity (Sm) with impaired accommodation to exercise. We tested the impact of an aldosterone antagonist on Sm at rest and post-exercise. Forty-nine HFpEF patients (65 ± 11 years, 24 male) with HF signs/symptoms, mitral E/Ea (annular early diastolic velocity) > 8, and left ventricular (LV) EF > 50% were randomized to spironolactone (25 mg/day, 25 patients) or the Control. At baseline and 6 months, we analyzed Sm of basal LV segments at rest and after a 6 min treadmill exercise. At 6 months, post-exercise mean Sm in the spironolactone group became greater than that in the Control (9.2 ± 1.6 vs. 8.3 ± 1.0 cm/s, p = 0.021), mainly due to the increment of post-exercise % increase of lateral Sm (44 ± 30 vs. 30 ± 19% at baseline, p = 0.045). Further analyses showed the presence of systolic dyssynchrony (standard deviation of electromechanical delay of 6-basal LV segments > 35 ms) was independently associated with a poorer response to spironolactone, defined as a post-exercise % increase of lateral Sm < 50% (OR = 2.7, 95% CI = 1.8–4.2) and the increment of Ea < 1.5 cm/s (OR = 1.5, 95% CI = 1.1–2.3). Spironolactone could improve exercise accommodation of regional systolic myocardial velocity for HFpEF patients. However, its benefits could be decreased in those with ventricular dyssynchrony. This suggested possible therapeutic impacts from underlying heterogeneity within HFpEF patients.

Altered regional myocardial velocities by tissue phase mapping and feature tracking in pediatric patients with hypertrophic cardiomyopathy.

Hypertrophic cardiomyopathy (HCM) is associated with heart failure, atrial fibrillation and sudden death. Reduced myocardial function has been reported in HCM despite normal left ventricular (LV) ejection fraction. Additionally, LV fibrosis is associated with elevated T1 and might be an outcome predictor. To systematically compare tissue phase mapping and feature tracking for assessing regional LV function in children and young adults with HCM and pediatric controls, and to evaluate structure-function relationships among myocardial velocities, LV wall thickness and myocardial T1. Seventeen pediatric patients with HCM and 21 age-matched controls underwent cardiac MRI including standard cine imaging, tissue phase mapping (two-dimensional cine phase contrast with three-directional velocity encoding), and modified Look-Locker inversion recovery to calculate native global LV T1. Maximum LV wall thickness was measured on cine images. LV radial, circumferential and long-axis myocardial velocity time courses, as well as global and segmental systolic and diastolic peak velocities, were quantified from tissue phase mapping and feature tracking. Both tissue phase mapping and feature tracking detected significantly decreased global and segmental diastolic radial and long-axis peak velocities (by 12-51%, P<0.001-0.05) in pediatric patients with HCM vs. controls. Feature tracking peak velocities were lower than directly measured tissue phase mapping velocities (mean bias = 0.3-2.9cm/s). Diastolic global peak velocities correlated moderately with global T1 (r = -0.57 to -0.72, P<0.01) and maximum wall thickness (r = -0.37 to -0.61, P<0.05). Both tissue phase mapping and feature tracking detected myocardial velocity changes in children and young adults with HCM vs. controls. Associations between impaired diastolic LV velocities and elevated T1 indicate structure-function relationships in HCM.

Accelerated magnetic resonance imaging tissue phase mapping of the rat myocardium using compressed sensing with iterative soft-thresholding.

IntroductionTissue Phase Mapping (TPM) MRI can accurately measure regional myocardial velocities and strain. The lengthy data acquisition, however, renders TPM prone to errors due to variations in physiological parameters, and reduces data yield and experimental throughput. The purpose of the present study is to examine the quality of functional measures (velocity and strain) obtained by highly undersampled TPM data using compressed sensing reconstruction in infarcted and non-infarcted rat hearts.MethodsThree fully sampled left-ventricular short-axis TPM slices were acquired from 5 non-infarcted rat hearts and 12 infarcted rat hearts in vivo. The datasets were used to generate retrospectively (simulated) undersampled TPM datasets, with undersampling factors of 2, 4, 8 and 16. Myocardial velocities and circumferential strain were calculated from all datasets. The error introduced from undersampling was then measured and compared to the fully sampled data in order to validate the method. Finally, prospectively undersampled data were acquired and compared to the fully sampled datasets.ResultsBland Altman analysis of the retrospectively undersampled and fully sampled data revealed narrow limits of agreement and little bias (global radial velocity: median bias = -0.01 cm/s, 95% limits of agreement = [-0.16, 0.20] cm/s, global circumferential strain: median bias = -0.01%strain, 95% limits of agreement = [-0.43, 0.51] %strain, all for 4x undersampled data at the mid-ventricular level). The prospectively undersampled TPM datasets successfully demonstrated the feasibility of method implementation.ConclusionThrough compressed sensing reconstruction, highly undersampled TPM data can be used to accurately measure the velocity and strain of the infarcted and non-infarcted rat myocardium in vivo, thereby increasing experimental throughput and simultaneously reducing error introduced by physiological variations over time.

Association of regional myocardial conduction velocity with the distribution of hypoattenuation on contrast-enhanced perfusion computed tomography in patients with postinfarct ventricular tachycardia

Cardiac magnetic resonance imaging has been shown to be beneficial for identification of the ventricular tachycardia (VT) substrate before catheter ablation. Contrast-enhanced perfusion multidetector computed tomography (CEP-MDCT) is more generalizable to clinical practice, and wall thickness and regional hypoenhancement on CEP-MDCT can identify potential substrate sites, albeit with decreased specificity. The purpose of this study was to evaluate the association between wall thickness and attenuation on CEP-MDCT with local conduction velocity (CV) and electrogram abnormalities in patients with postinfarct VT. Fourteen patients with postinfarct VT underwent preprocedural CEP-MDCT followed by endocardial electroanatomic mapping (EAM) and ablation. Myocardial attenuation and wall thickness were calculated from 3-dimensional MDCT images using ADAS-VT software (Galgo Medical). EAM was registered with 3-dimensional MDCT images using the CartoMERGE module of CARTO3 software (Biosense Webster). Local CV was calculated by averaging the velocity between each point and 5 adjacent points with concordant wavefront direction. A total of 3689 points were included. In multivariable regression analysis clustered by patient, local CV was positively associated with myocardial attenuation, bipolar voltage, unipolar voltage, and wall thickness. Each 10-HU drop in full-thickness attenuation correlated to 2.6% decrease in CV (P <.001) and 5.5% decrease in bipolar voltage amplitude (P <.001), after adjusting for wall thickness. Myocardial attenuation distribution on CEP-MDCT is associated with regional CV and electrogram amplitude. Regions with low CV identified with low attenuation on CEP-MDCT may serve as important VT substrates in postinfarct patients.

Regional myocardial motion in patients with mild cognitive impairment: a pilot study

BackgroundCardiovascular disease (CVD) is a risk factor for cognitive impairment in the elderly. Manifestations of subclinical CVDs can be found in patients with cognitive impairment. The aim of the present study was to test the hypothesis that patients with mild cognitive impairment (MCI) have different magnetic resonance imaging (MRI)-derived regional myocardial motion indices compared with healthy controls.MethodsEleven MCI patients (age, 65.5 years ±5.9; range, 55–81 years old) and 11 sex−/age-matched healthy volunteers were enrolled. All of the participants underwent a head MRI and cardiac MRI. Global cortical atrophy (GCA) was graded on the head MRI. The left ventricular ejection fraction (LVEF) and regional strain, strain rate, displacement and velocity were measured on cine images. The GCA scores, global cardiac function and regional myocardial motion indices were compared between MCI patients and healthy controls using the t-test.ResultsMCI patients had a higher GCA score than healthy controls (p = 0.048). However, there was no significant difference in LVEF between MCI patients and controls. Compared to healthy controls, MCI patients had a lower peak radial strain (29.1% ± 24.1% vs. 46.4% ± 43.4%, p < 0.001), lower peak diastolic radial strain rate (3.2 ± 2.4 s− 1 vs. 6.0 ± 3.0 s− 1, p < 0.001), lower peak diastolic circumferential strain rate (2.5 ± 2.1 s− 1 vs. 3.2 ± 2.1 s− 1, p = 0.002), lower peak systolic radial displacement (4.2 ± 2.2 mm vs. 5.2 ± 3.3 mm, p = 0.002), lower peak diastolic radial velocity (31 ± 18 mm/s vs. 45 ± 33 mm/s, p < 0.001), and lower peak diastolic circumferential velocity (178 ± 124 degree/s vs. 217 ± 131 degree/s, p = 0.005).ConclusionMRI-derived regional myocardial strain, strain rate and velocity were found to be different between MCI patients and healthy controls. Regional myocardial motion indices have the potential to become novel quantitative imaging biomarkers for representing the risk of neurodegenerative disorders, such as Alzheimer’s disease (AD).

Prediction of the ischemic origin of functional mitral regurgitation in patients with systolic heart failure through posterior mitral leaflet angle.

BACKGROUNDDifferentiating ischemic from non-ischemic functional mitral regurgitationý (FMR) in patients with cardiomyopathy is important in terms of the therapeutic decision-making and prognosis, but might be clinically challenging. In this study, the deformation of mitral valve (MV) indices in the prediction of the etiology of FMR was assessed using 2D transthoracic and tissue Doppler echocardiography.METHODSThis case-control study was conducted from April 2015 to January 2016 in Imam Reza Hospital in Mashhad, Iran. The participants consisted of 40 patients with ischemic cardiomyopathy (ICM) and 22 with non-ischemic dilated cardiomyopathy (DCM) who referred to the heart failure clinic. Transthoracic echocardiography was performed using the conventional 2D and tissue Doppler imaging (TDI). MV tenting area (TA), coaptation distance (CD), anterior and posterior mitral leaflet angles (AMLA and PMLA), and regional systolic myocardial velocity (Sm) were measured.RESULTSThere were no significant differences in echocardiographic indices between the two groups, besides Sm and PMLA which were significantly lower and higher, respectively, in ICM subjects in comparison with DCM patients (P = 0.002). PMLA ≥ 40 degrees and Sm ≤ 4 cm/second have a relatively high value for discriminating the ischemic from non-ischemic origin of functional MR in subjects with systolic heart failure (sensitivity: 80.0% and 70.0%, specificity: 73.0% and 77.3%; P = 0.001 and P < 0.001; respectively). Multivariable logistic regression identified PMLA and anterior Sm as major determinants for ischemic MR {Odds ratio (OR) [95% confidence interval (CI)] = 0.89 (0.82-0.96), P = 0.003, OR (95% CI) = 0.29 (0.14-0.60), P = 0.001, respectively}.CONCLUSIONThe present study showed that PMLA and Sm had an independent significant association with the mechanism of FMR. These findings are suggestive of the predictive role of mitral deformation echocardiographic indices in the determination of the etiology of FMR in systolic heart failure.

Evaluación ecocardiográfica intraoperatoria de la función del ventrículo derecho y su correlación con la evolución postoperatoria

BackgroundIt is demonstrated that the dysfunction of the right ventricle (RV) has bad prognosis. Intraoperative assessment of the RV function by echocardiography is difficult, because of it's complex anatomy. Tissue Doppler imaging is a new ultrasound tool that measures regional myocardial velocities in systole. ObjectiveThe purpose of this study was to evaluate the correlation of intraoperative RV s’ velocity with length of intensive care unit, hospital stays and severe cardiovascular complications after a non-cardiac surgery. Material and methodsSystolic velocity (s’) was obtained from the lateral tricuspid annular site. ResultsSeventy-three patients (ASA II 24%, ASA III 46% and ASA IV 16%), 53% male, 65±11 years were studied. RV s’ velocity was measured easily in all patients. RV s’ lower than 11.3cm/s was considered abnormal and it correlated with longer hospitalization (P<.05). There were no stadistically differences in cardiovascular complications. DiscussionThis study shows that intraoperative RV s’ velocity was a good predictor of length of intensive care unit stay (P<.05) and length of hospitalization (P<.01). Having a clinical predictor that is easily obtainable, non-invasive and readily available can be useful, so a non-invasive assessment of RV function can be important to identify potential higher risk patients with bad RV function undergoing non-cardiac surgery.

Regional wall motion abnormalities during early diastole in patients with hypertensive left ventricular hypertrophy: a Doppler tissue echocardiographic study.

To investigate left ventricular wall motion asynchrony in patients with hypertensive heart disease, we measured regional myocardial velocity in hypertensive patients with left ventricular hypertrophy and in normotensive individuals using tissue Doppler imaging. The endocardial velocity and the myocardial velocity gradient were measured in the basal and mid segments of the septal and posterior walls. The dilating velocity of the left ventricular cavity were determined for the basal and mid ventricular segments of left ventricle. The peak myocardial velocity gradient was significantly lower in the hypertensive group than in the control group for all regions. The peak endocardial velocity during early diastole in the mid ventricular septum was significantly lower in the hypertensive group (Hypertensive vs Controls; 3.8 +/- 1.3 vs 5.1 +/1.6 cm/s, P < 0.05), whereas the peak endocardial velocity at the other three sites were similar in the two groups. The peak dilating velocity was significantly lower in the hypertensive group only in the mid portion of the left ventricle (Hypertensive vs Controls; 7.2 +/- 2.4 vs 9.8 +/- 1.3 s(-1), P < 0.005). These results suggest that there were regional wall motion abnormalities and nonuniformity during the early diastolic phase in the hypertensive hearts with left ventricular hypertrophy.

Left Ventricular Dyssynchrony in Acute ST Elevated Myocardial Infarction in Patients with Normal QRS duration

Background: The aim of this study was to assess left ventricular dyssynchrony after acute ST elevated myocardial infarction (STEMI) in patients with normal QRS duration. Real time 3D echocardiography (RT3DE) with triplane tissue synchronization imaging (TSI) used to identify segmental left ventricular systolic velocity in ejection phase to evaluate LV dyssynchrony in patients with STEMI and the findings were compared with control.Materials and methods: RT3DE with triplane TSI was performed within 4 days of AMI after thrombolysis or primary PCI in 31 patients and compared with 31 agematched controls. Regional myocardial velocities were assessed in 12 segments in ejection phase, and the corresponding time to peak systolic velocity (Ts) was measured. To assess LV dyssynchrony Ts-4, Ts-6, Ts- SD-6, Ts-12 and Ts-SD-12 were computed by offline dedicated software semi-automatically.Results: The dyssynchrony parameters were significantly prolonged in patients with AMI. Among the dyssynchrony parameters TS-SD-12 was better indicator of LV dyssynchrony. The Ts-SD-12 was significantly prolonged in the STEMI group when compared with controls. In patients with acute STEMI mean Ts-SD-12 was 43.2±19.1 milliseconds whereas in control group it was 23.0 ±6.5 milliseconds (p&lt;0.05). The Ts-SD-12 was prolonged in patients with Anterior than Inferior STEMI as follows respectively 45.9± 17.6 and 40.0± 21 milliseconds.Conclusions: Triplane TSI by RT3DE is useful in evaluating LV dyssynchrony in patients with acute STEMI and even in those with normal QRS duration there is significant left ventricular dyssynchrony early after STEMI.Bangladesh Heart Journal 2015; 30(1) : 13-21

Reproducibility and observer variability of tissue phase mapping for the quantification of regional myocardial velocities.

To systematically investigate the reproducibility of global and segmental left ventricular (LV) velocities derived from tissue phase mapping (TPM). Breath held and ECG synchronized TPM data (spatial/temporal resolution = 2 × 2mm(2)/20.8ms) were acquired in 18 healthy volunteers. To analyze scan-rescan variability, TPM was repeated in all subjects during a second visit separated by 16 ± 5 days. Data analysis included LV segmentation, and quantification of global and regional (AHA 16-segment modal) metrics of LV function [velocity-time curves, systolic and diastolic peak and time-to-peak (TTP) velocities] for radial (Vr), long-axis (Vz) and circumferential (VΦ) LV velocities. Mean velocity time curves in basal, mid-ventricular, and apical locations showed highly similar LV motion patterns for all three velocity components (Vr, VΦ, Vz) for scan and rescan. No significant differences for both systolic and diastolic peak and TTP myocardial velocities were observed. Segmental analysis revealed similar regional peak Vr and Vz during both systole and diastole except for three LV segments (p = 0.045, p = 0.033, and p = 0.009). Excellent (p < 0.001) correlations between scans and rescan for peak Vr (R(2) = 0.92), peak Vz (R(2) = 0.90), radial TTP (R(2) = 0.91) and long-axis TTP (R(2) = 0.88) confirmed good agreement. Bland-Altman analysis demonstrated excellent intra-observer and good inter-observer analysis agreement but increased variability for long axis peak velocities. TPM based analysis of global and regional myocardial velocities can be performed with good reproducibility. Robustness of regional quantification of long-axis velocities was limited but spatial velocity distributions across the LV could reliably be replicated.

Heart deformation analysis: measuring regional myocardial velocity with MR imaging.

The aim of the present study was to test the hypothesis that heart deformation analysis (HDA) may serve as an alternative for the quantification of regional myocardial velocity. Nineteen healthy volunteers (14 male and 5 female) without documented cardiovascular diseases were recruited following the approval of the institutional review board (IRB). For each participant, cine images (at base, mid and apex levels of the left ventricle [LV]) and tissue phase mapping (TPM, at same short-axis slices of the LV) were acquired within a single magnetic resonance (MR) scan. Regional myocardial velocities in radial and circumferential directions acquired with HDA (Vrr and Vcc) and TPM (Vr and VФ) were measured during the cardiac cycle. HDA required shorter processing time compared to TPM (2.3 ± 1.1min/case vs. 9.5 ± 3.7min/case, p < 0.001). Moderate to good correlations between velocity components measured with HDA and TPM could be found on multiple myocardial segments (r = 0.460-0.774) and slices (r = 0.409-0.814) with statistical significance (p < 0.05). However, significant biases of velocity measures at regional myocardial areas between HDA and TPM were also noticed. By providing comparable velocity measures as TPM does, HDA may serve as an alternative for measuring regional myocardial velocity with a faster image processing procedure.

Co-registered MR tissue phase mapping and speckle tracking echocardiography: inter-modality comparison of regional myocardial velocities in pediatric patients

Background MR tissue phase mapping (TPM) enables assessment of regional myocardial velocities. The purpose of this study was to compare regional myocardial velocities obtained by both TPM and speckle tracking echocardiography (STE) to assess agreement and potential systematic differences between modalities. Methods

Effect of obesity on left ventricular longitudinal myocardial strain by speckle tracking echocardiography in children and adolescents.

Impaired subclinical ventricular function may contribute to the risk of cardiovascular disease in obesity. The aim of this study was to determine the influence of obesity on left ventricular (LV) longitudinal myocardial function in normotensive obese children using two-dimensional (2D) speckle tracking echocardiography (STE). Case-control study. Sixty normotensive obese children aged 10-16 years (mean age, 13.9±2.3 years) were compared with 50 normal-weight controls. Obese participants had a body mass index (BMI)≥95(th) percentile. Regional strain/strain rate (SR) values were compared with left ventricular (LV) parameters. The correlation was studied by linear regression analysis. Obese subjects exhibited a significantly higher LV end-diastolic diameter, left atrium/aortic diameter ratio, and LV mass/index when compared to controls (p<0.001). Left ventricular ejection fraction and regional systolic myocardial velocities were similar in the obese and control groups. By 2D STE, regional strain of both the septal wall (average strain: -16.0±3.9% vs -21.9±2.4%, p<0.001) and lateral wall (average strain: -15.6±2.3% vs -22.9±3.5%, p<0.001); regional SR of both the septal wall (average SRsys: -0.7±0.22 s(-1) vs -1.3±0.32 s(-1), p<0.001) and lateral wall (average SRsys: -0.67±0.19 s(-1) vs -1.33±0.31 s(-1), p<0.001); regional SRE/A of both the septal wall (average SRE/A: 1.8±0.83 vs. 2.2±0.91, p: 0.004) and lateral wall (average SRE/A: 1.4±0.43 vs. 2.4±1.21, p<0.001); and global strain (-14.6±7.34% vs -20.9±3.24%, p<0.001) were lower in the obese group compared with the controls. These strain imaging parameters appear to be related to the severity of obesity and can contribute to increased BMI. Left ventricular mass was found to be correlated with a decrease in global LV strain. Our study showed that childhood obesity is associated with an alteration in the longitudinal LV function. Segmental analysis of the LV can provide subtle markers for the emergence of future obesity-related cardiac disease.

Extracellular volume fraction is more closely associated with altered regional left ventricular velocities than left ventricular ejection fraction in nonischemic cardiomyopathy.

Nonischemic cardiomyopathy is a common cause of left ventricular (LV) dysfunction and myocardial fibrosis. The purpose of this study was to noninvasively evaluate changes in segmental LV extracellular volume (ECV) fraction, LV velocities, myocardial scar, and wall motion in nonischemic cardiomyopathy patients. Cardiac MRI including pre- and postcontrast myocardial T1 mapping and velocity quantification (tissue phase mapping) of the LV (basal, midventricular, and apical short axis) was applied in 31 patients with nonischemic cardiomyopathy (50±18 years). Analysis based on the 16-segment American Heart Association model was used to evaluate the segmental distribution of ECV, peak systolic and diastolic myocardial velocities, scar determined by late gadolinium enhancement, and wall motion abnormalities. LV segments with scar or impaired wall motion were significantly associated with elevated ECV (rs =0.26; P<0.001) and reduced peak systolic radial velocities (r=-0.43; P<0.001). Regional myocardial velocities and ECV were similar for patients with reduced (n=12; ECV=0.28±0.06) and preserved left ventricular ejection fraction (n=19; ECV=0.30±0.09). Patients with preserved left ventricular ejection fraction showed significant relationships between increasing ECV and reduced systolic (r=-0.19; r=-0.30) and diastolic (r=0.34; r=0.26) radial and long-axis peak velocities (P<0.001). Even after excluding myocardial segments with late gadolinium enhancement, significant relationships between ECV and segmental LV velocities were maintained indicating the potential of elevated ECV to identify regional diffuse fibrosis not visible by late gadolinium enhancement, which was associated with impaired regional LV function. Regionally elevated ECV negatively affected myocardial velocities. The association of elevated regional ECV with reduced myocardial velocities independent of left ventricular ejection fraction suggests a structure-function relationship between altered ECV and segmental myocardial function in nonischemic cardiomyopathy.

Regional left ventricular myocardial T1 and velocity mapping: elevated extracellular volume fraction is associated with altered myocardial velocities

Background Non-ischemic cardiomyopathy (NICM) is a common cause of left ventricular (LV) dysfunction and may be associated with myocardial fibrosis. Global LV systolic function may underestimate the impact of fibrosis on myocardial function and is insensitive to regional abnormalities in myocardial motion. Advances in cardiac MRI have enabled quantification of myocardial fibrosis through the calculation of the gadolinium extracellular volume fraction (Ve) using T1 mapping techniques employing the modified look-locker inversion recovery (MOLLI) correction. In addition, tissue phase mapping (TPM) enables assessment of regional myocardial velocities. The purpose of this study was to evaluate the impact of regional myocardial fibrosis on regional myocardial velocities. We hypothesize that regional scar will correlate with reduced regional systolic and diastolic velocities.

Spiral tissue phase velocity mapping in a breath-hold with non-cartesian SENSE.

Tissue phase velocity mapping (TPVM) is capable of reproducibly measuring regional myocardial velocities. However acquisition durations of navigator gated techniques are long and unpredictable while current breath-hold techniques have low temporal resolution. This study presents a spiral TPVM technique which acquires high resolution data within a clinically acceptable breath-hold duration. Ten healthy volunteers are scanned using a spiral sequence with temporal resolution of 24 ms and spatial resolution of 1.7 × 1.7 mm. Retrospective cardiac gating is used to acquire data over the entire cardiac cycle. The acquisition is accelerated by factors of 2 and 3 by use of non-Cartesian SENSE implemented on the Gadgetron GPU system resulting in breath-holds of 17 and 13 heartbeats, respectively. Systolic, early diastolic, and atrial systolic global and regional longitudinal, circumferential, and radial velocities are determined. Global and regional velocities agree well with those previously reported. The two acceleration factors show no significant differences for any quantitative parameter and the results also closely match previously acquired higher spatial resolution navigator-gated data in the same subjects. By using spiral trajectories and non-Cartesian SENSE high resolution, TPVM data can be acquired within a clinically acceptable breath-hold.

Diastolic asynchrony and myocardial dysfunction in patients with univentricular heart after Fontan operation.

We aimed to assess the existence of myocardial dysfunction and intra-univentricular diastolic asynchrony in patients after Fontan operation. Twenty patients after Fontan procedure and 30 age-matched controls were included in the study. The global function of the univentricular heart was analyzed by the Tei index. Regional myocardial velocities and strain of the univentricular heart including the rudimentary right ventricle (RV) were quantified by tissue Doppler imaging. Intra-univentricular or intra left ventricular (LV) diastolic delay was measured from the difference of diastolic intervals (time to peak early diastolic velocity), measured at LV lateral wall and the rudimental RV wall in patients, or LV lateral wall and the ventricular septum in controls. Compared to the control group, patients after Fontan operation had significantly elevated Tei index (0.24±0.02 vs. 0.41±0.1, p<0.001). On the other hand, the regional myocardial velocities and strains of the univentricular heart including the rudimentary RV were significantly reduced (p<0.001). Among patients, there was a significant correlation between the Tei index of the univentricular ventricle and rudimentary RV strain (r=-0.66, p=0.01). The heart rate-corrected intra-univentricular diastolic delay was significantly prolonged among patients when compared to the intra-LV diastolic delay in controls (0.01±0.9 vs. 1±1.1, p=0.005). Myocardial dysfunctions and intra-univentricular diastolic asynchrony of the univentricular heart in patients after Fontan procedure are evident. The rudimentary RV in patients after Fontan procedure plays an important role in the determination of the global function of the univentricular heart.

Determinants of Functional Mitral Regurgitation Severity in Patients with Ischemic Cardiomyopathy versus Nonischemic Dilated Cardiomyopathy

Functional mitral regurgitation (MR) is prevalent among patients with left ventricular (LV) dysfunction and is associated with a poorer prognosis. Our aim was to assess the primary determinants of MR severity in patients with ischemic cardiomyopathy (ICM) and nonischemic dilated cardiomyopathy (DCM). Patients with functional MR secondary to ICM (n=55) and DCM (n=48) were prospectively enrolled. Effective regurgitant orifice (ERO) area, global LV remodeling, regional wall-motion abnormalities, and mitral apparatus deformity indices were assessed utilizing conventional and tissue Doppler echocardiography. ICM patients had more severe MR compared with DCM patients despite similar ejection fraction and functional status (ERO=0.16±0.08cm(2) vs. ERO=0.12±0.70cm(2) , respectively, P=0.002). Regional myocardial systolic velocities in mid-inferior and mid-lateral wall were negatively correlated with ERO in ICM and DCM patients, respectively. Multivariate analysis identified coaptation height as the only independent determinant of ERO in both groups. In a subset of ICM patients (n=9) with relatively high ERO despite low coaptation height, a higher prevalence of left bundle branch block was detected (88.9% vs. 46.7%, P=0.02). Functional MR severity was chiefly determined by the extent of mitral apparatus deformity, and coaptation height can provide a rapid estimation of MR severity in heart failure patients. Additional contributory mechanisms in ICM patients include depressed myocardial systolic velocities in posteromedial papillary muscle attaching site and evidence of global LV dyssynchrony.