Ventricular Mechanics Research Articles

Two-dimensional Strain Echocardiography Differentiates Cardiac Amyloidosis from Hypertrophic Cardiomyopathy with Preserved Ejection Fraction

Background: Ejection fraction is a poor parameter to assess left ventricular function in ventricular hypertrophy. It is highlyimportant to analyze aspects of ventricular mechanics that could differentiate cardiac amyloidosis from hypertrophic cardiomyopathy.Objective: The aim of this study was to compare longitudinal strain and other ventricular mechanical parameters betweenpatients with hypertrophic cardiomyopathy and cardiac amyloidosis, both with preserved ejection fraction.Methods: A comparative, prospective study was conducted in 15 patients with cardiac amyloidosis [Group (G) 1] and 15 patientswith hypertrophic cardiomyopathy (G2), both presenting preserved ejection fraction (>50%). Patients were analyzedwith speckle tracking echocardiography and strain and left ventricular (LV) rotational parameters. Longitudinal strain wasobtained from apical 4-, 3- and 2-chamber planes. Circumferential strain and ventricular rotation were obtained from LVtransverse planes. Twist: algebraic sum of apical and basal rotation (°), torsion [twist/LV base-apex distance (o/cm)] and thenew parameters: deformation product (global longitudinal strain × apical circumferential strain); deformation index: [twist/longitudinal strain (°/%)] and ejection fraction/global longitudinal strain ratio were calculated.Results: Patients with cardiac amyloidosis presented significantly lower ejection fraction (58.08%±6.16 vs. 67.15%±8.09;p=0.012) and global longitudinal strain values (–12.61%±4.32 vs. –17.15%±3.95; p=0.008) at the expense of basal segments.No significant differences were found for twist, torsion, and circumferential and radial strain. The product between longitudinalstrain and apical circumferential strain decreased, while the ejection fraction/global longitudinal strain ratio wassignificantly increased in patients with cardiac amyloidosis.Conclusions: The product of longitudinal strain × apical circumferential strain and the ejection fraction/global longitudinalstrain ratio are useful parameters that allow differentiating cardiac amyloidosis from hypertrophic cardiomyopathy patients.

Left ventricular rotational abnormalities following successful kidney transplantation-insights from the three-dimensional speckle-tracking echocardiographic MAGYAR-Path Study.

Kidney transplantation (KTx) is the preferred treatment for virtually all suitable candidates with end-stage renal disease. There is limited information on left ventricular (LV) rotational mechanics post-KTx, therefore the present study aimed to assess it and to compare it to that of age- and gender-matched healthy controls. The present study comprised 42 KTx patients, from which 4 patients were excluded due to insufficient image quality (mean age: 46.3±8.2 years, 29 males). Control group consisted of 81 age- and gender-matched healthy individuals (mean age: 43.5±10.8 years, 51 males). All KTx patients and healthy controls successfully underwent transthoracic two-dimensional (2D) Doppler echocardiography and three-dimensional speckle-tracking echocardiography (3DSTE). Significant differences could be demonstrated in LA diameter, LV end-diastolic diameter and volume, interventricular septum, LV posterior wall thickness, LV ejection fraction and early and late filling transmitral flow velocities and in their ratio between KTx patients and controls; none of the subjects examined showed grade 2-4 mitral and/or tricuspid regurgitations. Three patients following successful KTx showed near absence of LV twist called as LV 'rigid body rotation' (RBR) movement. When the remaining 35 post-KTx patients were analysed separately, reduced basal LV rotation could be demonstrated in post-KTx patients with tendentious increase in apical LV rotation resulting in an unchanged LV twist. KTx is associated with alterations in LV rotational mechanics with unchanged LV twist suggesting a remodelling of this sort of movement. The near absence of LV twist (LV-RBR) could be demonstrated in some post-KTx cases.

Twelve-Lead ECG Optimization of Cardiac Resynchronization Therapy in Patients With and Without Delayed Enhancement on Cardiac Magnetic Resonance Imaging.

BackgroundDelayed enhancement (DE) on magnetic resonance imaging is associated with ventricular arrhythmias, adverse events, and worse left ventricular mechanics. We investigated the impact of DE on cardiac resynchronization therapy (CRT) outcomes and the effect of CRT optimization.Methods and ResultsWe studied 130 patients with ejection fraction (EF) ≤40% and QRS ≥120 ms, contrast cardiac magnetic resonance imaging, and both pre‐ and 1‐year post‐CRT echocardiograms. Sixty‐three (48%) patients did not have routine optimization of CRT. The remaining patients were optimized for wavefront fusion by 12‐lead ECG. The primary end point in this study was change in EF following CRT. To investigate the association between electrical dyssynchrony and EF outcomes, the standard deviation of activation times from body‐surface mapping was calculated during native conduction and selected device settings in 52 of the optimized patients. Patients had no DE (n=45), midwall septal stripe (n=30), or scar (n=55). Patients without DE had better ∆EF (13±10 versus 4±10 units; P<0.01). Optimized patients had greater ∆EF in midwall stripe (2±9 versus 12±12 units; P=0.01) and scar (0±7 versus 5±10; P=0.04) groups, but not in the no‐DE group. Patients without DE had greater native standard deviation of activation times (P=0.03) and greater ∆standard deviation of activation times with standard programming (P=0.01). Device optimization reduced standard deviation of activation times only in patients with DE (P<0.01).Conclusions DE on magnetic resonance imaging is associated with worse EF outcomes following CRT. Device optimization is associated with improved EF and reduced electrical dyssynchrony in patients with DE.

Clinical applications of feature-tracking cardiac magnetic resonance imaging.

Cardiovascular diseases represent the leading cause of mortality and morbidity in the western world. Assessment of cardiac function is pivotal for early diagnosis of primitive myocardial disorders, identification of cardiac involvement in systemic diseases, detection of drug-related cardiac toxicity as well as risk stratification and monitor of treatment effects in patients with heart failure of various etiology. Determination of ejection fraction with different imaging modalities currently represents the gold standard for evaluation of cardiac function. However, in the last few years, cardiovascular magnetic resonance feature tracking techniques has emerged as a more accurate tool for quantitative evaluation of cardiovascular function with several parameters including strain, strain-rate, torsion and mechanical dispersion. This imaging modality allows precise quantification of ventricular and atrial mechanics by directly evaluating myocardial fiber deformation. The purpose of this article is to review the basic principles, current clinical applications and future perspectives of cardiovascular magnetic resonance myocardial feature tracking, highlighting its prognostic implications.

Quantitative Gadolinium-Free Cardiac Fibrosis Imaging in End Stage Renal Disease Patients Reveals A Longitudinal Correlation with Structural and Functional Decline

Patients with end stage renal disease (ESRD) suffer high mortality from arrhythmias linked to fibrosis, but are contraindicated to late gadolinium enhancement magnetic resonance imaging (MRI). We present a quantitative method for gadolinium-free cardiac fibrosis imaging using magnetization transfer (MT) weighted MRI, and probe correlations with widely used surrogate markers including cardiac structure and contractile function in patients with ESRD. In a sub-group of patients who returned for follow-up imaging after one year, we examine the correlation between changes in fibrosis and ventricular structure/function. Quantification of changes in MT revealed significantly greater fibrotic burden in patients with ESRD compared to a healthy age matched control cohort. Ventricular mechanics, including circumferential strain and diastolic strain rate were unchanged in patients with ESRD. No correlation was observed between fibrotic burden and concomitant measures of either circumferential or longitudinal strains or strain rates. However, among patients who returned for follow up examination a strong correlation existed between initial fibrotic burden and subsequent loss of contractile function. Gadolinium-free myocardial fibrosis imaging in patients with ESRD revealed a complex and longitudinal, not contemporary, association between fibrosis and ventricular contractile function.

Physiological left ventricular segmental myocardial mechanics: Multiparametric polar mapping to determine intraventricular gradients of myocardial dynamics.

We investigated physiological systolic left ventricular (LV) myocardial mechanics and gradients to provide a database for later studies of diseased hearts. The analyses were performed in 131 heart-healthy individuals and included seven parameters of myocardial mechanics using speckle tracking echocardiography (STE). Basal to apical and circumferentially significant physiological intraventricular parameter gradients of myocardial activity were determined. Global mean values and segmental ranges were peak systolic longitudinal strain -21.2±3.3%, 95% confidence interval [CI] -21.8% to -20.6%), gradient (basal to apical) -16.0% to -26.7%; peak systolic longitudinal strain rate -1.24±0.31%/s, 95% CI -1.29% to -1.19%/s, gradient (basal to apical) -0.91% to -1.61%/s; post-systolic index 2.6±3.2%, 95% CI 3.15%-2.05%, gradient (basal/medial/apical) 7.0/1.2/2.4%; pre-systolic stretch index 1.3±2.7%, 95% CI 1.77%-0.83%, gradient (basal/medial/apical) 6.5/0.2/1.3%; peak longitudinal displacement 12.2±2.6mm, 95% CI 12.6-11.8mm, gradient (basal to apical) 21.0-3.4mm; time-to-peak longitudinal strain 370±43ms, 95% CI 377-363ms, gradient (basal to apical) 396-361ms; and time-to-peak longitudinal strain rate 180±47ms, 95% CI 188-172ms, gradient (basal to apical) 150-200ms. This study generated a database of seven STE-derived parameters of physiological segmental and global myocardial LV mechanics. The resulting sets of three-dimensional intraventricular mappings of the entire LV provide physiological parameter gradients in baso-apical and circumferential direction by applying the 17-segment polar model. This will facilitate comparison of systolic myocardial activity of the healthy LV with diseased or otherwise altered (eg, sports) hearts.

Two-dimensional speckle tracking echocardiography predicts early subclinical cardiotoxicity associated with anthracycline-trastuzumab chemotherapy in patients with breast cancer

BackgroundCombined anthracycline-trastuzumab chemotherapy has been associated with LV dysfunction. We aimed to assess early changes in left ventricular (LV) and right ventricular (RV) mechanics associated with combined anthracycline-trastuzumab treatment for breast cancer. As well as explore whether early changes in 2-dimensional (2D)–speckle tracking echocardiography (STE) could predict later chemotherapy-induced cardiotoxicity.MethodsSixty-six patients with breast cancer who received anthracycline-trastuzumab treatment were included (mean [±SD] age, 52 [9] years). Echocardiograms were available for analysis with 2D-STE at the following time points: pretreatment (T0), first cycle (T1), and second cycle (T2) of combined chemotherapy. All patients had a normal pretreatment LV ejection fraction (LVEF). Cardiotoxicity was defined as a decrease in LVEF of at least 10 percentage points from baseline on follow-up echocardiography.ResultsCardiotoxicity developed in 13 of the 66 patients (20%). The mean (±SD) LVEF at T0 was 66% (±6); at T1 60% (±7); and at T2, 54% (±6). For the 53 patients without cardiotoxicity, the LVEF was 65% (±4%) at T0, 63% (±5%) at T1, and 62% (±4) at T2. Global longitudinal strain (GLS) at T1 was the strongest indicator of subsequent cardiotoxicity (area under the curve, 0.85; cutoff value, − 14.06; sensitivity, 91%; specificity, 83%; P = .003). Compared with baseline (T0), left ventricular longitudinal strain, LV circumferential strain, circumferential peak systolic strain rate (SR), circumferential peak early diastolic SR, right ventricular longitudinal strain, and longitudinal peak systolic SR at T1 and T2 were reduced significantly in patients with cardiotoxicity (P < .05).ConclusionsAnthracycline-trastuzumab treatment leads to early deterioration of LV GLS, circumferential strain, and systolic SR. Right ventricular GLS and SR were also affected. Early changes in GLS are good predictors of subsequent development of anthracycline-trastuzumab–induced cardiotoxicity.

Ventricular mechanics in adolescent and adult patients with a Fontan circulation: Relation to geometry and wall stress.

Patients with single ventricle physiology and Fontan circulation are at increased risk for late complications and reduced survival. The aim of the study was to investigate the correlation between ventricular geometry and systolic regional function in different underlying anatomic conditions in adolescent and adult Fontan-palliated patients. In a retrospective cross-sectional study, we measured 2D strain, ventricular diameters, ventricular volumes, ejection fraction (EF), global and segmental wall stress, and sphericity index. The same analyses were performed in 99 age- and gender-matched healthy individuals. One hundred and one patients were included at a mean age of 21 (range 14-59) years. In comparison with healthy subjects, patients with Fontan circulation displayed larger ventricular volumes (153±78mL vs 116±38mL P<0.05), reduced EF (43%±15% vs 55%±8% P<0.05), reduced longitudinal (-13%±6% vs -21%±4% P<0.05) and circumferential strain values (-15%±7% vs -22%±4% P<0.05). Functionally single ventricles were more spherical (ratio of longitudinal to short-axis diameters 1.3±0.3 vs 1.7±0.2 P<0.05). Circumferential strain correlated well with global wall stress and the degree of sphericity (R2 =0.320), while segmental strain did not correlate with segmental wall stress. The percentage of segments with akinesia was relatively high (16±16% vs 0±0% P<0.05) indicating reduced segmental contractile function. Functionally single ventricles after Fontan palliation have significantly reduced systolic regional and global function with a high intersegmental inhomogeneity. The underlying pathological mechanisms might be multifactorial, including ventricular geometry, sphericity, and regional contractile properties. Future studies are needed to investigate the role of ventricular geometry for clinical performance and outcome.

Strain and Rotational Mechanics in Children With Single Left Ventricles After Fontan

Left ventricular (LV) mechanics in patients with different single morphologic LV subtypes, including tricuspid atresia, double-inlet left ventricle, and pulmonary atresia with intact ventricular septum, remain poorly studied. Given that histologic studies indicate differences in LV myocardial fiber orientation, we hypothesized that this may result in altered LV mechanics. The aim of this study was to evaluate the influence of LV morphology on LV mechanics. Fifty-two children with single left ventricles after Fontan operation and age-matched control subjects were prospectively enrolled. Using two-dimensional speckle-tracking echocardiography, longitudinal strain was measured in the four-, three-, and two-chamber long-axis planes, and circumferential strain was measured at the basal, mid, and apical short-axis planes. Apical and basal rotation were measured, and twist and torsion were calculated. We compared strain and rotational mechanics in cases versus control subjects and among LV subtypes. Compared with control subjects, subjects with single left ventricles had similar LV end-diastolic dimensions but significantly decreased ejection fractions. The single left ventricle cohort had normal global longitudinal strain (P=.20) but lower basal mean circumferential strain (P<.0001). Single left ventricle subjects had higher apical rotation (P=.0001) but decreased basal rotation (P=.0007); there was no difference in twist but increased torsion (P=.001). LV subtypes had different four-chamber (P=.01), two-chamber (P=.006), and global longitudinal strain (P=.01), lowest in the pulmonary atresia with intact ventricular septum subtype. Longitudinal LV strain was preserved in children with single left ventricles after Fontan. A pattern of reduced basal circumferential strain and rotation with an increase in apical rotation and torsion in the single left ventricle cohort may be related to differences in myofiber orientation, increased fibrosis, and the impact of altered loading conditions throughout palliation. Decreased longitudinal strain in the pulmonary atresia with intact ventricular septum group may also reflect detrimental interventricular interactions.

Successful radiofrequency catheter ablation of atrial fibrillation is associated with improvement in left ventricular energy loss and mechanics abnormalities.

Dissipative energy loss (EL), an index of inefficient blood flow, has not been studied in patients with atrial fibrillation (AF). We therefore assessed the effect of AF and of successful catheter ablation on left ventricular (LV) EL and global longitudinal strain (GLS) to explore the effect of inefficient blood flow on LV remodeling. In 53 patients undergoing catheter ablation for AF (AF group), LV EL (in mW/m) was evaluated by vector flow mapping (VFM) during systole (ELsys), early diastole (ELed) and atrial contraction phase (ELac), and GLS was calculated by two-dimensional tissue tracking (2DTT). Of the 53 patients, 37 patients who sustained sinus rhythm and completed echocardiographic evaluation at baseline and at 3 and 6months follow-up were examined for change in EL and GLS. The latter parameters also were assessed in 44 age- and sex-matched controls. At baseline in AF group, ELsys and ELed were significantly higher (3.97 ± 2.29 vs. 3.14 ± 1.01; and 9.22 ± 5.01 vs. 3.89 ± 1.51; both P < 0.05, respectively), and GLS was lower (- 16.66 ± 3.50 vs. - 19.95 ± 2.40, P < 0.05) than in controls. During follow-up after catheter ablation, ELsys and ELed significantly improved at 3months, and almost normalized at 6months (both P < 0.05); GLS also improved significantly (P < 0.05). In multivariate logistic regression analysis, ELed was the only independent predictor for maintenance of sinus rhythm at 1-year follow-up (hazard ratio, 1.254; 95% confidence interval 1.073-1.467). VFM and 2DTT revealed impaired LV EL and GLS in patients with AF. Successful catheter ablation appeared to ameliorate impairment in intraventricular flow and mechanics.

A16846 Prognostic Value of Speckle Tracking Echocardiography in Peripartum Cardiomyopathy

Objectives: The aim of the study is to evaluate left ventricular cardiac mechanics in a population of pregnant women with per partum cardiomyopathy and preeclampsia (PE) during different stages of pregnancy. Methods: he study population included 42 pregnant women with PE, after IVF, 10 of them with multiple pregnancy (46.5 ± 3 years) and 20 healthy nonpregnant women (33 ± 4years). Apical and basal short axis and apical view for three, two and four chamber for 2D images were acquired (65 ± 7 frames/s) during the first, second and third trimester of the pregnancy, as well as up to two months post partum. Results: eak LVT and LVUR increased significantly in the 3rd trimester in both pregnancy groups (13.48 ± 2.90°,13.12 ± 3.30°,16.83 ± 3.61°,P < 0.001; and − 111.52 ± 23.54°/sec, − 107.40 ± 26.58°/sec, − 144.30 ± 45.14°/sec, P < 0.001; in the 1st, 2nd, and 3rd trimester, respectively. The pregnants with twins have the highest value for LVT and LVUR compare with other pregnants (p < 0.01), but in the last trimester, the time to peak LVUR is prolonged. An independent correlation was found between the change in LVT and LV end-systolic volume in 1st and 3rd trimester (r = 0,56). Peak LVUR at the 3rd trimester correlated significantly with LV end-diastolic volume. Multiple regression analysis indicates that only systolic blood pressure (r = 0.394, P = 0.005) was an independent predictor for increased LV torsion. Arterial hypertension (AH) and prevalence of preeclampsia (PE) are more often in IVF group. Longitudinal strain decreased significantly (p < 0.001) during 3th trimester Global longitudinal strain measures of the LV were non-significantly different between the different groups in first and second trimester (GLS-20.6 ± 3,14 vs. − 19,29 ± 2,17). Conclusion: Global longitudinal strain is the main predictor of new onset peripartum cardiomyopathy.

Echocardiographic Measurements of Right Ventricular Mechanics in Infants with Bronchopulmonary Dysplasia at 36 Weeks Postmenstrual Age

To test the hypothesis that specific echocardiographic measurements of right ventricular (RV) mechanics at 36 weeks postmenstrual age (PMA) are associated with the severity of bronchopulmonary dysplasia (BPD). A subset of 93 preterm infants (born between 27 and 29 weeks of gestation) was selected retrospectively from a prospectively enrolled cohort. BPD was defined using the National Institutes of Health workshop definition, with modifications for oxygen reduction testing and altitude. The cohort was divided into no-BPD and BPD groups using previously published methodology for analyses. Echocardiographic measurements of RV function (ie, tricuspid annular plane systolic excursion, fractional area of change, systolic-to-diastolic ratio, tissue Doppler myocardial performance index, and RV strain), RV remodeling/morphology (end-systolic left ventricular eccentricity index), and RV afterload (pulmonary artery acceleration time measure) were evaluated at 36 weeks PMA. Multivariable logistic regression determined associations between RV measurements and BPD severity. Compared with the no-BPD cohort, the BPD group had lower birth weight z-scores (P = .04) and trended toward a male predominance (P = .08). After adjusting for birth weight z-score, gestational age, and sex, there were no between-group differences in echocardiographic measurements except for the eccentricity index (scaled OR [0.1-unit increase], 1.49; 95% CI, 1.13-2.12; P = .01). Among conventional and emerging echocardiographic measurements of RV mechanics, eccentricity index was the sole variable independently associated with BPD severity in this study. The eccentricity index may be a useful echocardiographic measurement for characterizing RV mechanics in patients with BPD at 36 weeks PMA.

Classical mechanical dyssynchrony is rare in transcatheter aortic valve implantation-induced left bundle branch block.

Left bundle branch block (LBBB) is a frequent conduction abnormality after transcatheter aortic valve implantation (TAVI). We aimed to investigate how TAVI procedure related conduction abnormalities influence ventricular mechanics and prognosis, with particular focus on new-onset persistent LBBB. A total of 140 consecutive patients with severe aortic stenosis (83 ± 8 years old, 49% women) undergoing TAVI in a single tertiary centre were included in a repeated measures study. Changes in myocardial function and contraction patterns were investigated in relation to changes in electrical conduction and afterload by speckle tracking echocardiography. Whether patients with new-onset LBBB acquired classical dyssynchronous contractions was assessed by longitudinal strain in apical four-chamber view. Global longitudinal strain improvement was seen in all patients (-15.1 ± 4.3 vs. -16.1 ± 3.9%, P < 0.01, n = 140), and all subgroups, regardless of pre-existing or procedure-acquired conduction abnormalities immediately after TAVI. New-onset LBBB fulfilling strict electrocardiogram (ECG) criteria was observed in 28 patients (20%). The vast majority of new-onset LBBB patients (n = 26, 93%) had homogenous contractions. Classical dyssynchronous LBBB contractions were only observed in 2 patients (7%) with new-onset LBBB. Patients with new-onset LBBB and patients without acquired conduction disorders had similar mortality rates during 19 ± 9 months of follow-up [11.1, 95% confidence interval (CI) 4.6-26.8 vs. 8.1, 95% CI 4.8-13.7 per 100 patients years, P = 0.53]. Classical dyssynchronous LBBB contractions were absent in most patients with new-onset post-TAVI LBBB, even when applying strict ECG criteria. Patients with and without new-onset LBBB experienced similar prognosis with regards to mortality.

Immediate improvement of left ventricular mechanics following transcatheter aortic valve replacement.

Left ventricular (LV) mechanics are impaired in patients with severe aortic stenosis (AS). Transcatheter aortic valve replacement (TAVR) has become a widespread technique for patients with severe AS considered inoperable or high risk for traditional open-surgery. This procedure could have a positive impact in LV mechanics. The aim of this study was to evaluate the immediate effect of TAVR on LV function recovery, as assessed by myocardial deformation parameters. One-hundred twelve consecutive patients (81.4 ± 6.4 years, 50% female) from 10 centres in Europe with severe AS who successfully underwent TAVR with either a self-expanding CoreValve (Medtronic, Minneapolis, MN) or a mechanically expanded Lotus valve (Boston Scientific, Natick, MA) were enrolled in a prospective multi-center study. A complete echocardiographic examination was performed at baseline and immediately before discharge, including the assessment of LV strain using standard two-dimensional images. Echocardiographic examination with global longitudinal strain (GLS) quantification could be obtained in 92 patients, because of echocardiographic and logistic reasons. Between examinations, a modest statistically significant improvement in GLS could be seen (GLS% -15.00 ± 4.80 at baseline;-16.15 ± 4.97 at discharge, p = 0.028). In a stratified analysis, only women showed a significant improvement in GLS and a trend towards greater improvement in GLS according to severity of systolic dysfunction as measured by LV ejection fraction could be noted. Immediate improvement in GLS was appreciated after TAVR procedure. Whether this finding continues to be noted in a more prolonged follow-up and its clinical implications need to be assessed in further studies.

Histogram Analysis of Native T1 Mapping and Its Relationship to Left Ventricular Late Gadolinium Enhancement, Hypertrophy, and Segmental Myocardial Mechanics in Patients With Hypertrophic Cardiomyopathy.

The use of native T1 mapping for evaluation of hypertrophic cardiomyopathy (HCM) is being explored, and its combination with histogram analysis may benefit the accuracy of such assessments. To investigate the relationship of segmental left ventricular wall thickness (LVWT), myocardial fibrosis, and strain parameters with segmental histogram parameters of native T1 mapping in HCM patients. Retrospective. Ninety-three HCM patients without previous cardiovascular diseases were included. 3.0T cardiac MR. Steady-state free precession cine imaging, modified Look-Locker inversion recovery, phase-sensitive inversion recovery. Images were assessed by three experienced radiologists. Mann-Whitney U-tests, area under the curve (AUC), Spearman's rank correlation, intraclass correlation coefficient, and Bland-Altman test were used for statistical analysis. A higher LVWT value correlated with higher means, minimums, 10th /25th /50th /75th /90th percentiles, maximums, kurtosis, entropy, and lower SD and energy of T1 mapping (P < 0.05 for all), with the correlation being stronger for entropy and energy (Spearman's rho = 0.439 and -0.413, respectively) than other parameters. Late gadolinium enhancement positive (LGE+) segments exhibited higher mean, minimum, 10th /25th /50th /75th /90th percentiles, maximum, entropy, and lower energy of T1 times than late gadolinium enhancement negative (LGE-) segments (P < 0.001 for all). Impaired strain function parameters (peak thickening and thickening rate in radial, circumferential, and longitudinal directions) demonstrated a weak correlation with higher entropy (P < 0.001 for all) and lower energy (P < 0.001 for all). Histogram parameters of native T1 mapping provide more information than mean T1 times alone. Among these parameters, entropy and energy may correlate better with LVWT, myocardial late gadolinium enhancement, and strain parameters than mean T1 times in HCM patients. 2 Technical Efficacy Stage: 2 J. Magn. Reson. Imaging 2019;49:668-677.

Distinct Occurrence of Proarrhythmic Afterdepolarizations in Atrial Versus Ventricular Cardiomyocytes: Implications for Translational Research on Atrial Arrhythmia.

Background: Principal mechanisms of arrhythmia have been derived from ventricular but not atrial cardiomyocytes of animal models despite higher prevalence of atrial arrhythmia (e.g., atrial fibrillation). Due to significant ultrastructural and functional differences, a simple transfer of ventricular proneness toward arrhythmia to atrial arrhythmia is critical. The use of murine models in arrhythmia research is widespread, despite known translational limitations. We here directly compare atrial and ventricular mechanisms of arrhythmia to identify critical differences that should be considered in murine models for development of antiarrhythmic strategies for atrial arrhythmia.Methods and Results: Isolated murine atrial and ventricular myocytes were analyzed by wide field microscopy and subjected to a proarrhythmic protocol during patch-clamp experiments. As expected, the spindle shaped atrial myocytes showed decreased cell area and membrane capacitance compared to the rectangular shaped ventricular myocytes. Though delayed afterdepolarizations (DADs) could be evoked in a similar fraction of both cell types (80% of cells each), these led significantly more often to the occurrence of spontaneous action potentials (sAPs) in ventricular myocytes. Interestingly, numerous early afterdepolarizations (EADs) were observed in the majority of ventricular myocytes, but there was no EAD in any atrial myocyte (EADs per cell; atrial myocytes: 0 ± 0; n = 25/12 animals; ventricular myocytes: 1.5 [0–43]; n = 20/12 animals; p < 0.05). At the same time, the action potential duration to 90% decay (APD90) was unaltered and the APD50 even increased in atrial versus ventricular myocytes. However, the depolarizing L-type Ca2+ current (ICa) and Na+/Ca2+-exchanger inward current (INCX) were significantly smaller in atrial versus ventricular myocytes.Conclusion: In mice, atrial myocytes exhibit a substantially distinct occurrence of proarrhythmic afterdepolarizations compared to ventricular myocytes, since they are in a similar manner susceptible to DADs but interestingly seem to be protected against EADs and show less sAPs. Key factors in the generation of EADs like ICa and INCX were significantly reduced in atrial versus ventricular myocytes, which may offer a mechanistic explanation for the observed protection against EADs. These findings may be of relevance for current studies on atrial level in murine models to develop targeted strategies for the treatment of atrial arrhythmia.

Gaussian Process Regressions for Inverse Problems and Parameter Searches in Models of Ventricular Mechanics

Patient specific models of ventricular mechanics require the optimization of their many parameters under the uncertainties associated with imaging of cardiac function. We present a strategy to reduce the complexity of parametric searches for 3-D FE models of left ventricular contraction. The study employs automatic image segmentation and analysis of an image database to gain geometric features for several classes of patients. Statistical distributions of geometric parameters are then used to design parametric studies investigating the effects of: (1) passive material properties during ventricular filling, and (2) infarct geometry on ventricular contraction in patients after a heart attack. Gaussian Process regression is used in both cases to build statistical models trained on the results of biophysical FEM simulations. The first statistical model estimates unloaded configurations based on either the intraventricular pressure or the end-diastolic fiber strain. The technique provides an alternative to the standard fixed-point iteration algorithm, which is more computationally expensive when used to unload more than 10 ventricles. The second statistical model captures the effects of varying infarct geometries on cardiac output. For training, we designed high resolution models of non-transmural infarcts including refinements of the border zone around the lesion. This study is a first effort in developing a platform combining HPC models and machine learning to investigate cardiac function in heart failure patients with the goal of assisting clinical diagnostics.

Evaluation of the effects of right ventricular pressure load on left ventricular myocardial mechanics in patients with chronic obstructive pulmonary disease by ultrasound speckle tracking imaging.

This paper aims to evaluate the effects of right ventricular pressure load on left ventricular myocardial mechanics in patients with chronic obstructive pulmonary disease (COPD) by ultrasound speckle tracking imaging. 119 patients with COPD and pulmonary hypertension (PH) were selected from December 2016 to March 2018 in Xuzhou Municipal Hospital Affiliated to Xuzhou Medical University. 42 healthy subjects were selected as control group. According to the pulmonary arterial systolic pressure (PASP), 41 patients were classified into mild group, 47 in moderate group, and 31 cases in severe group. Echocardiography and STI were used to measure the indexes. Compared with those in control group, EI and E/e of moderate group and severe group increased significantly (p<0.001). Compared with those in control group, parameters in moderate and severe groups significantly decreased (p<0.001), including early diastolic mitral annular velocity/late peak blood flow velocity (E/A), left ventricular end diastolic volume (LVEDV), left ventricular end-systolic volume (LVESV), PASP and left ventricular end-diastolic diameter (LVEDD), stroke volume (SV), left ventricular end-systolic diameter (LVESD), cardiac output (CO), peak rotation angle and peak time of in the basal and apical segments. Compared with those in control group, parameters in moderate group significantly decreased (p<0.001), including left ventricular strain parameters segmental systolic peak longitudinal strain (LS), circumferential strain (CS), and radial strain (RS). Compared with those in control group, parameters in mild group significantly decreased (p<0.001), including peak rotation angle of basal segment and apical segment of the left ventricle. Compared with those in moderate group, peak rotation angle and peak time of the whole basal segment and apical segment of severe group gradually decreased (p<0.001). Left ventricular whole peak rotation angle can be used to sensitively evaluate the change of left ventricular myocardial mechanics function in PH patients, and can reflect changes of left ventricular myocardial mechanics function in patients with COPD when mild PH occurs.

P4673Impact of pulmonary pressures on the functional shift in right ventricular mechanics after mitral valve surgery: initial results of the PREPARE-MVR study

P4673Impact of pulmonary pressures on the functional shift in right ventricular mechanics after mitral valve surgery: initial results of the PREPARE-MVR study

P2849Independent association between left ventricular midwall mechanics and global longitudinal strain in native hypertensive patients

P2849Independent association between left ventricular midwall mechanics and global longitudinal strain in native hypertensive patients