Performance Of Left Ventricle Research Articles

Left ventricular systolic performance in adults after arterial switch operation. Echocardiographic data from EPOCH-ASO: a multi-centric international registry

Abstract Background The arterial switch operation (ASO) is the current technique of choice for the repair of the transposition of the great arteries (d-TGA). Its main advantage is that the left ventricle (LV) sustains the systemic circulation, thus diminishing the risk of late systolic dysfunction as seen in the atrial switch technique. Purpose To study the systolic LV performance in a large cohort of adult patients after ASO and to explore clinical determinants of reduced left ventricular systolic function (LVSF). Methods EPOCH-ASO is an ongoing prospective, multicentre, international cohort study involving 11 reference centres from 5 different countries, that includes adult d-TGA patients after ASO. We conducted a cross-sectional analysis of clinical and echocardiographic data from all patients enrolled in EPOCH-ASO. LVSF was considered reduced when ejection fraction (EF) by Simpson’s method was < 54% in women or <52% in men, or by visual assessment when EF could not be obtained. Results 513 patients have been included in EPOCH-ASO, with a median age of 25.3 years [IQR: 21 – 28 years] at the time of enrolment. At baseline, 41% had history of at least one reintervention (23.2% at the right ventricular outflow tract (RVOT), 5.1% at the left ventricular outflow tract (LVOT), 4.5% at the aortic arch, 3.3% pacemaker implantation). Echocardiographic data were obtained in 450 patients (88 % of the total cohort). Left ventricular ejection fraction (LVEF) by biplane Simpson method was available in 316 patients (mean LVEF 58.3 ± 7.2%), while visual assessment of LVSF was performed in 134 patients. For the total cohort with echocardiographic data available, 62 (13.8%) had a reduced LVSF. Global longitudinal strain (GLS) analysis was available in 145 patients (28.2% of the total cohort), with a mean value of -17.4% ±2.7%. GLS was impaired (>-18%) in 53% of the patients. Furthermore, 48% of the 117 patients with normal LVEF had a reduced GLS. Older age at the time of the echocardiography, late repair (>12th day), a previous pulmonary banding or having a pacemaker implanted were factors associated with an impaired LVSF. In the multivariate analysis, age at the time of the echocardiography (OR 1.06 per year, CI 1.01-1.12; p<0.001) and late repair (OR 1.85, CI 1.11-3.06, p=0.03) remained significant. As for the speckle tracking analysis, a significantly lower GLS was found in patients after LVOT intervention (-15% vs -17.6%, p=0.005) and with a neo-aortic root above the median (37.5 mm) (GLS -17% vs -18%, p=0.03). In the multivariate analysis only LVOT intervention remained significant (p=0.016). Conclusions Left ventricular systolic dysfunction is not exceptional in patients after ASO and it may become a concern as this population ages. Speckle tracking analysis might identify earlier stages of ventricular dysfunction. Large comprehensive longitudinal studies are needed to better characterize the left ventricular systolic function in this patient population.

Simultaneously Assessed Three-Dimensional Speckle-Tracking Echocardiography-Derived Left Ventricular and Left Atrial Volumes Are Associated in Healthy Adults-Findings from the MAGYAR-Healthy Study.

The left atrium (LA) has a significant role in regulating blood flow from veins to the left ventricle (LV). LV performance is affected by several factors including preload, which is partly, but highly, dependent on LA volumes. The aim of the present study is to perform simultaneous assessment of LA and LV volume changes during the cardiac cycle in healthy circumstances. Therefore, LA and LV volumes and volume-based functional properties were determined in healthy adults, and the associations of these parameters were examined. The present study consists of 164 healthy adults (age: 33.0 ± 12.3 years, 82 males) being in sinus rhythm. All subjects have undergone complete two-dimensional Doppler echocardiography with three-dimensional speckle-tracking echocardiography (3DSTE). Increased end-systolic maximum LA volume was associated with higher LV volumes and reduced LV ejection fraction. Very high early pre-atrial contraction and late diastolic LA volumes were associated with increased LV volumes, reduced LV ejection fraction and increased LV mass. Increased LA volumes were associated with increased LV mass. Higher LV volumes were associated with tendentiously higher LA volumes. Higher LV end-diastolic volume was associated with tendentiously higher all LA stroke volumes (SVs) and total and active LA emptying fractions (EFs). Higher LV end-systolic volume was associated with tendentiously higher all LA SVs but preserved all LA EFs. 3DSTE is capable of simultaneous assessment of LA and LV volumes and volume-based functional properties for (patho)physiologic studies. Moreover, 3DSTE-derived LV and LA volumes and functional properties show strong associations.

Myocardial work in children with Wolff-Parkinson-White syndrome.

Wolff-Parkinson-White Syndrome (WPW) has been associated with reduced local myocardial deformation, and when left ventricular dysfunction is present, catheter ablation of the accessory pathway may be required, even in asymptomatic patients. We aimed to evaluate the diagnostic value of non-invasive myocardial work in predicting subtle abnormalities in myocardial performance in children with WPW.Seventy-five paediatric patients (age 8.7 ± 3.5years) were retrospectively recruited for the study: 25 cases with manifest WPW and 50 age- and sex- matched controls (CTR). Global myocardial work index (MWI) was measured as the area of the left ventricle (LV) pressure-strain loops. From MWI, global Myocardial Constructive Work (MCW), Wasted Work (MWW), and Work Efficiency (MWE) were estimated. In addition, standard echocardiographic parameters of LV function were evaluated. Despite normal LV ejection fraction (EF) and global longitudinal strain (GLS), children with WPW had worse MWI, MCW, MWW, and MWE. At multivariate analysis, MWI and MCW were associated with GLS and systolic blood pressure, and QRS was the best independent predictor of low MWE and MWW. In particular, a QRS > 110ms showed good sensitivity and specificity for worse MWE and MWW values. In children with WPW, myocardial work indices were found significantly reduced, even in the presence of normal LV EF and GLS. This study supports the systematic use of myocardial work during the follow-up of paediatric patients with WPW. Myocardial work analysis may represent a sensitive measure of LV performance and aid in decision-making.

Association of Gestational Age at Birth With Left Cardiac Dimensions at Near-Term Corrected Age Among Extremely Preterm Infants

Remodeling and altered ventricular geometry have been described in adults born preterm. Although they seem to have an adverse cardiac phenotype, the impact of various degrees of prematurity on cardiac development has been scarcely reported. In this study, we evaluated the impact of gestational age (GA) at birth on cardiac dimensions and function at near-term age among extremely preterm infants. This is a retrospective single-center cohort study of infants born at <29weeks ofGA between 2015 and 2019. Infants with available clinically acquired echocardiography between 34 and 43weeks were included. Two groups were investigated: those born <26weeks and those born ≥26weeks. All measurements were done by an expert masked to clinical data using the raw images. The primary outcome was measurements of cardiac dimensions and function based on GA group. Secondary outcomes were the association between cardiac dimensions and postnatal steroid exposure and with increments of GA at birth. A total of 205 infants were included (<26weeks, n=102; ≥26weeks, n=103). At time of echocardiography, weight (2.4±0.5 vs 2.5±0.5kg, P=.86) and age (37.2±1.6 vs 37.1±1.9weeks, P=.74) were similar between groups. There was no difference in metrics of right-sided dimensions and function. However, left-sided dimensions were decreased in infants born <26weeks, including systolic left ventricle (LV) diameter (1.06±0.20cm vs 1.12±0.18cm, P=.02), diastolic LV length (2.85±0.37 vs 3.02±0.57cm, P=.02), and estimated LV end-diastolic volume (5.36±1.69 vs 6.01±1.79mL, P=.02). In our cohort of very immature infants, birth at the extreme of prematurity was associated with smaller left cardiac dimensions around 36weeks of corrected age. Future longitudinal prospective studies should evaluate further the impact of prematurity on LV development and performance and their long-term clinical impact.

JCS/JHRS 2021 guideline focused update on non-pharmacotherapy of cardiac arrhythmias.

JCS/JHRS 2021 guideline focused update on non-pharmacotherapy of cardiac arrhythmias.

Outcomes of double switch procedure in patients with congenitally corrected transposition of the great arteries with or without associated VSD

Anatomical repair by double switch procedure (DS) for patients with congenitally corrected transposition of the great arteries (ccTGA) remains under debate. The outcomes after DS for ccTGA without LVOTO, with specific focus on the left ventricle (LV) performance in patients with intact ventricular septum (IVS) were assessed. Since 1994, 39 patients underwent DS: 9 had an IVS, and 30 had an associated VSD. Palliative procedure consisted in pulmonary artery banding (PAB) for 31 patients (79%): 9 (twice in 5) for tricuspid regurgitation (TR) and 22 for hemodynamically significant associated VSD. Survival and LV performance in follow up were analyzed. PAB was efficient to diminish TR significantly in all 9. The median age at repair was 22 months (12 days–13 years). Associated VSD closure was performed in 76% of patients ( n = 30). Four patients required peri-operative pacemaker implantation. Hospital mortality occurred in 1 (2.5%: 70% CI 1–8%) neonate who underwent DS and aortic arch repair: he died because of low output syndrome. Two (5%) patients required early reoperation for pulmonary venous pathway stenosis release. Median follow up was 13.7 years (range: 3 months–26 years). Two late deaths occurred 16 and 84 months postoperatively because of refractory LV dysfunction: both patients had IVS and benefited from LV retraining. Six patients (16%) required 7 reoperations during follow up. At last visit, 5 patients (14%) presented with LV dysfunction (LV ejection fraction < 50%) requiring medical treatment while remaining 31 (84%) were asymptomatic. Actuarial survival curves are shown in Fig. 1 . Mortality was significantly higher in the IVS group compared to the VSD group (33% vs. 0%, P = 0.01). The DS appeared to be the procedure of choice for ccTGA associated with VSD. PAB was efficient for the management of TR in early life. Our Results suggest that the strategy of LV retraining by PAB to achieve DS at any price remains questionable.

Echocardiographic Reference Ranges of Non-invasive Myocardial Work Indices in Children.

Global myocardial work (GMW) is an emerging method to characterize left ventricle (LV) function with potential advantages over both ejection fraction and global longitudinal strain (GLS). We aimed to determine the feasibility and reproducibility for echocardiographic-derived GMW in a healthy pediatric population; establish normal reference values; and investigate the influence of age, gender, and other clinical factor on normal reference ranges. We prospectively enrolled 212 individuals (median age of 9years; interquartile range, 6 to 12years, 112 female). Global work index (GWI), global constructive work (GCW), global wasted work (GWW), and global work efficiency (GWE) were measured from LV pressure-strain loops. Quantification of GMW was performed using a GE Vivid E95 system and available software package (Echopac V.203, GE). The mean LV EF was 64 ± 3% with GLS of -21.3 ± 1.5%. GWI was 1688 ± 219mmHg% with mean GWE of 96.5 ± 1.4%. The GCW was 1959 ± 207mmHg%, and the mean GWW of 61.1 ± 30.9mmHg%. No significant difference was found in MW indices across age group and gender (p > 0.05 for all). There were significant correlations between both GWI and GCW with GLS and systolic blood pressure (p < 0.001), but not with GWE and GWW. Linear regression model revealed that GWI and GCW were more closely correlated with systolic blood pressure than GLS. LV MW indices had good intra-observer and inter-observer reproducibility. This study establishes both the feasibility and reference ranges for non-invasive echocardiographic indices of GMW in healthy children. Myocardial work appears to be a complementary modality to assess LV performance in children.

Radiomics side experiments and DAFIT approach in identifying pulmonary hypertension using Cardiac MRI derived radiomics based machine learning models

Side experiments are performed on radiomics models to improve their reproducibility. We measure the impact of myocardial masks, radiomic side experiments and data augmentation for information transfer (DAFIT) approach to differentiate patients with and without pulmonary hypertension (PH) using cardiac MRI (CMRI) derived radiomics. Feature extraction was performed from the left ventricle (LV) and right ventricle (RV) myocardial masks using CMRI in 82 patients (42 PH and 40 controls). Various side study experiments were evaluated: Original data without and with intraclass correlation (ICC) feature-filtering and DAFIT approach (without and with ICC feature-filtering). Multiple machine learning and feature selection strategies were evaluated. Primary analysis included all PH patients with subgroup analysis including PH patients with preserved LVEF (≥ 50%). For both primary and subgroup analysis, DAFIT approach without feature-filtering was the highest performer (AUC 0.957–0.958). ICC approaches showed poor performance compared to DAFIT approach. The performance of combined LV and RV masks was superior to individual masks alone. There was variation in top performing models across all approaches (AUC 0.862–0.958). DAFIT approach with features from combined LV and RV masks provide superior performance with poor performance of feature filtering approaches. Model performance varies based upon the feature selection and model combination.

Evaluation of the Left Ventricular Hemodynamic Status of Double-Root Translocation Patients Through Vector Flow Mapping.

The double-root translocation (DRT) procedure is considered as a new choice for surgical management of complex congenital heart disease. Our study aims to investigate the left ventricular hemodynamic status after DRT by energy loss (EL), involving 42 patients who underwent DRT as well as 42 healthy volunteers as controls. The EL of left ventricle (LV) during different periods (rapid filling-RF, atrial contraction-AC, isovolumic contraction-IVC, rapid ejection-RE) of the same cardiac cycle were obtained and analyzed. Compared to the controls, global LV and apical three chamber-EL at AC and IVC periods in DRT group were higher (p < 0.05), and EL at RE period of DRT group was moderately lower. In the correlation analysis, the global EL at the RF was correlated with E wave (r = 0.47, p = 0.03), E/e' (r = 0.50, p = 0.02), BSA (r = -0.54, p = 0.01), and age (r = -0.67, p < 0.001). AC and RE- global EL were significantly correlated with E/e' (r = 0.49, r = 0.59, p < 0.05). There was a strong positive correlation between E/e' and global EL at the IVC (r = 0.62, p = 0.003) and a moderate negative correlation with age (r = -0.44, p = 0.04). The present study confirms that EL is a feasible and reproducible indicator for quantitatively evaluating LV hemodynamic status in patients who underwent DRT and reveals that DRT can lead to approximatively normal long-term hemodynamic performance of LV.

The Hole of Hope: Balloon Atrial Septostomy for Left Ventricle Unloading during VA ECMO

Veno arterial extracorporeal membrane oxygenation (VA-ECMO) is an established rescue therapy for cardiogenic shock (CS). However, the increase in left ventricle (LV) afterload associated with inappropriate LV unloading remains an unsolved problem. Balloon atrial septostomy (BAS) is an inexpensive effective with low complication rates. Our purpose was to understand BAS effect in this setting. Observational retrospective study, including patients submitted to BAS for LV unloading during VA-ECMO support due to CS between 2018 and 2019. Inotropic use was evaluated by the Wernovsky inotropic score. Statistical analysis was performed by median comparison with Wilcoxon test for related samples. Four patients with refractory CS despite VA-ECMO and intra aortic balloon pump (n=3) or Impella (n=1) support were included. The age of the patients was 55.5 years (IQR 46.8-64.3) and 75% were male. The basal median LV ejection fraction was 29.5%. All had severe functional mitral regurgitation and ischemic heart disease (n=3) or severe aortic stenosis (n=1). BAS was performed after a median time of 8 days (IQR 5.5-12.0) after ECMO with a final dimension of 5 mm. The reduction in left atrial pressure led to resolution of pulmonary edema in all patients. There was a hemodynamic improvement after the procedure, with lower inotropic use in 75% of patients (median difference -0,6; p= 1.00), and reduction in pulmonary pressures and lactate levels (Table 1). Additionally we documented an increase in LV outflow tract (LVOT) velocity time integral (VTI) and in the PaO2/FiO2 ratio. After a follow-up of 25.5 days (IQR 12.8-45.8) half of the patients were weaned from VA-ECMO or transplanted. One procedure was complicated by a femoral hematoma. Percutaneous BAS is a simple and effective procedure to treat refractory pulmonary edema during VA-ECMO support. The improvement in LV performance, documented by the increase in LVOT VTI, is likely due to improvement in intracavitary pressures and a better oxygenation.

Increasing venoarterial extracorporeal membrane oxygenation flow puts higher demands on left ventricular work in a porcine model of chronic heart failure

BackgroundVenoarterial extracorporeal membrane oxygenation (VA ECMO) is widely used in the treatment of circulatory failure, but repeatedly, its negative effects on the left ventricle (LV) have been observed. The purpose of this study is to assess the influence of increasing extracorporeal blood flow (EBF) on LV performance during VA ECMO therapy of decompensated chronic heart failure.MethodsA porcine model of low-output chronic heart failure was developed by long-term fast cardiac pacing. Subsequently, under total anesthesia and artificial ventilation, VA ECMO was introduced to a total of five swine with profound signs of chronic cardiac decompensation. LV performance and organ specific parameters were recorded at different levels of EBF using a pulmonary artery catheter, a pressure–volume loop catheter positioned in the LV, and arterial flow probes on systemic arteries.ResultsTachycardia-induced cardiomyopathy led to decompensated chronic heart failure with mean cardiac output of 2.9 ± 0.4 L/min, severe LV dilation, and systemic hypoperfusion. By increasing the EBF from minimal flow to 5 L/min, we observed a gradual increase of LV peak pressure from 49 ± 15 to 73 ± 11 mmHg (P = 0.001) and an improvement in organ perfusion. On the other hand, cardiac performance parameters revealed higher demands put on LV function: LV end-diastolic pressure increased from 7 ± 2 to 15 ± 3 mmHg, end-diastolic volume increased from 189 ± 26 to 218 ± 30 mL, end-systolic volume increased from 139 ± 17 to 167 ± 15 mL (all P < 0.001), and stroke work increased from 1434 ± 941 to 1892 ± 1036 mmHg*mL (P < 0.05). LV ejection fraction and isovolumetric contractility index did not change significantly.ConclusionsIn decompensated chronic heart failure, excessive VA ECMO flow increases demands and has negative effects on the workload of LV. To protect the myocardium from harm, VA ECMO flow should be adjusted with respect to not only systemic perfusion, but also to LV parameters.

Cardiac performance after an endurance open water swimming race

Endurance exercise competitions have shown a transient negative effect on global right ventricular (RV) performance. Most published studies are based on terrestrial sports. The aim of our study was to evaluate the cardiac effects after an open water swimming race. We evaluated 33 healthy swimmers (mean age 40.9 ± 7.2) participating in a 9.5km open water swimming race. All subjects underwent a standard transthoracic echocardiography including an evaluation of dimensions and myocardial ventricular deformation. Echocardiography was performed 24h before and within the first hour of arrival at the finish line. Cardiac troponin I (cTn I), NT-ProBNP and leukocytes were also evaluated. No changes in left ventricle (LV) ejection fraction or LV global longitudinal strain were observed. A significant increase in RV end-diastolic area (RVEDA) was noted after the race (RVEDA at baseline 15.12 ± 1.86; RVEDA after race 16.06 ± 2.27, p < 0.05), but no changes were seen in RV fractional area change or RV global longitudinal strain. Cardiac biomarkers and leukocytes significantly increased. No association was detected between the increase in cTn I or NT-proBNP and the RV acute dilatation or LV performance. A significant association was observed between cTn I and leukocytes (r = 0.375, p < 0.05). An acute RV dilatation but without an impairment in RV deformation was observed after participating in an endurance swimming race. The correlation between the increase in cTn I and leukocytes, but not with ventricular performance, may support the hypothesis of an exercise-induced increase in myocardial sarcolemmal permeability due to an inflammatory response rather than myocardial injury.

Assessment of wall stresses and mechanical heart power in the left ventricle: Finite element modeling versus Laplace analysis.

IntroductionStenotic aortic valve disease (AS) causes pressure overload of the left ventricle (LV) that may trigger adverse remodeling and precipitate progression towards heart failure (HF). As myocardial energetics can be impaired during AS, LV wall stresses and biomechanical power provide a complementary view of LV performance that may aide in better assessing the state of disease.ObjectivesUsing a high‐resolution electro‐mechanical (EM) in silico model of the LV as a reference, we evaluated clinically feasible Laplace‐based methods for assessing global LV wall stresses and biomechanical power.MethodsWe used N = 4 in silico finite element (FE) EM models of LV and aorta of patients suffering from AS. All models were personalized with clinical data under pretreatment conditions. Left ventricle wall stresses and biomechanical power were computed accurately from FE kinematic data and compared with Laplace‐based estimation methods, which were applied to the same FE model data.Results and ConclusionLaplace estimates of LV wall stress are able to provide a rough approximation of global mean stress in the circumferential‐longitudinal plane of the LV. However, according to FE results, spatial heterogeneity of stresses in the LV wall is significant, leading to major discrepancies between local stresses and global mean stress. Assessment of mechanical power with Laplace methods is feasible, but these are inferior in accuracy compared with FE models. The accurate assessment of stress and power density distribution in the LV wall is only feasible based on patient‐specific FE modeling.

Effects of Different Heart Dimensions on Race Performance in Thorougbred Race Horses

Background: Athletic superiority could be present in horses with a specific cardiac phenotype that differs between race types. Measurement of chamber dimensions is considered one of the most important tools for assessing heart disease severity and prognosis as well as for evaluating cardiac responses to training and detraining. The purpose of this study was to evaluate the changes of cardiac dimensions and pathological finding in intensive exercise of Thoroughbred horses on their race performance by using the 2-D Doppler and M-Mode echocardiography according to their age, body weight and sex.Materials, Methods &amp; Results: Thoroughbred horses (40 females and 40 males) in the facilities, Ankara and Istanbul of Racetract, of Jockey Club of Turkey were included in the study. Horses were assigned as 4 study groups according to their ages and body weight separately. Group IV and I non-race horses were &gt;7 year-old and &gt;490 kg, &gt;1 to ≤2 and ≤ 390 kg, Group II and III race horses were &gt;2 to ≤3 and &gt;390 kg to ≤ 440 kg, &gt;3 to ≤6 year-old and &gt;440 kg to ≤490 kg, respectively. Intensive exercise was applied to horses except group IV. The relationships between selected echocardiographic variables according to horse age, body weight and sex were analysed. Specifically left ventricle (LV) assessment by diameter in systole and diastole (LVDd and LVDs) and posterior wall thickness (LVWs and LVWd), interventricular septal thickness (IVSd and IVSs), ejection fraction (EF), fractional shortening (FS), Stroke Volume (SV), cardiac output (CO) and left ventricle mass (LVM) were determined. Descriptive statistical analyses, including mean and standard deviation were used to summarise the data. Significant differences of LVDd (P &lt; 0.001), LVDs (P &lt; 0.001) and SV (P &lt; 0.001) were only determined in group I compared to group IV non-race horses. Significant differences in values of CO (P &lt; 0.001) was determined in group III compared to group II race horses, which shows the eccentric left ventricle hypertrophy developed in Thoroughbred horses during years of racing, especially more than 4 years old of intensive exercise. Present study indicated that linear relationships between echocardiographic variables and age (P &lt; 0.001) and body weight (P &lt; 0.001) were found, with the linear relationships between echocardiographic variables and age being stronger than those with body weight.Discussion: Relationships between echocardiographic measurements and body weight (BW) seem to be stronger than those with age. In horses, the effects of training and growth on echocardiographic measurements have been documented, and the influence of breed has been suggested by several authors. Also, it has been demonstrated that an eccentric cardiac hypertrophy occurs in response to race training attributable to an increased diastolic stress and thus, higher heart chambers are expected in the trained Thoroughbreds and Standardbreds horses. The lack of significant differences between age groups in several LV performance indices, such as FS% and EF% might indicate that the values reported here can be extrapolated to Thorougbred horses of different ages and BW. The homogeneity of racehorse management and their closed breeding population should allow unique insights into the subtle differences in cardiac adaptations that might be associated with small differences in training horses for different race disciplines.

Comprehensive computational assessment of blood flow characteristics of left ventricle based on in-vivo MRI in presence of artificial myocardial infarction

BackgroundUnderstanding the effects of cardiac diseases on the heart's functionality which is the purpose of many biomedical researches, directly affects the diagnostic and therapeutic methods. Myocardial infarction (MI) is a common complication of cardiac ischemia, however, the impact of MI on the left ventricle (LV) flow patterns has not been widely considered by computational fluid dynamics studies thus far. MethodsIn this study, we present an insightful numerical method that creates an artificial MI on an image-based fluid-structure interactional model of normal LV to investigate its influence on the flow in comparison with the normal case. Seventeen different models were developed to evaluate the effects of location, percentage, myocardial material properties and dilation size of MI on the LV's performance, area strain, wall displacement, pressure-volume loop, wall shear stress and velocity field. ResultsThe results show that MI considerably changes blood flow features which are fully dependent on MI parameters. For the case of constant MI location, the effect of a decrease of infarcted myocardium stiffness, increase of dilation size and increase of MI percentage are mostly similar. Although the location differences of MI under other constant conditions have similar impact on the ejection fraction, they also lead to dissimilar variations in the LV flow pattern and other indicators. ConclusionsThe presented model showed a capable computational method for investigating various mechanical MI conditions with respect to cardiac flow pattern. The perspective of this model development seems to be an applicable tool for MI clinical diagnosis and prediction of complications related to MI.

Simulation of Left Ventricular Dynamics Using a Low-Order Mathematical Model

The eventual goal of this study is to develop methods for estimating dynamic stresses in the left ventricle (LV) that could be used on-line in clinical settings, based on routinely available measurements. Toward this goal, a low-order theoretical model is presented, in which LV shape is represented using a small number of parameters, allowing rapid computational simulations of LV dynamics. The LV is represented as a thick-walled prolate spheroid containing helical muscle fibers with nonlinear passive and time-dependent active contractile properties. The displacement field during the cardiac cycle is described by three time-dependent parameters, using a family of volume-preserving mappings based on prolate spheroidal coordinates. Stress equilibrium is imposed in weak form and the resulting force balance equations are coupled to a lumped-parameter model of the circulation, leading to a system of differential–algebraic equations, whose numerical solution yields predictions of LV pressure and volume, together with spatial distributions of stresses and strains throughout the cardiac cycle. When static loading of the passive LV is assumed, this approach yields displacement and stress fields that closely match results from a standard finite-element approach. When dynamic motion with active contraction is simulated, substantial variations of fiber stress and strain through the myocardium are predicted. This approach allows simulations of LV dynamics that run faster than real time, and could be used to determine patient-specific parameters of LV performance on-line from clinically available measurements, with the eventual goal of real-time, patient-specific analysis of cardiac parameters.

Markers of increased risk in primary mitral regurgitation.

Myxomatous degaeneration is the most common etiology of primary mitral regurgitation (MR) in the developed world (1). Severe MR can impose significant hemodynamic stress on the left ventricle (LV). However, LV can remain in a compensated asymptomatic stage for long time with preserved ejection fraction (EF). After long period of time, EF drops and overt heart failure ensues (2). Mitral surgery is the cornerstone in management of severe MR to halt this process. Nonetheless, LV sustains subclinical structural and microscopic damage early before traditional indications for MV surgery is met (3). Current class I indications for MV surgery are development of symptoms or abnormal ejection fraction (4), and both of these conditions are associated with non-optimal postoperative outcomes. There is a growing concern that EF does not reflect true LV systolic function and it merely reflects ventricular ejection which is a fraction derived from end diastolic volume (EDV) (5). In conditions with supra-physiological EDV and reduced afterload such as severe MR, EF is doomed to be normal even in suboptimal LV performance. LV global longitudinal strain (LV-GLS), which measures myocardial systolic deformation, has been proposed to be more reflective of true LV systolic function (6). As a result to the aforementioned factors, timing of surgery in asymptomatic severe MR patients with preserved EF remains a challenging and a controversial decision (7). With the new advances in cardiac surgery and improvements in perioperative care, postoperative mortality in patients undergoing MV surgery in the last few years is less than 0.1%, with hospital stay as short as 5 days and more than 97% success rate in achieving trivial MR with MV repair (8), which argues for earlier intervention in patients with severe MR before it is too late.

Prognostic Implication of Strain Analysis in Patients with ST-Segment Elevation Myocardial Infarction: One More Evidence for Ever-Debatable Topic.

REFER TO THE PAGE 128-134 What is essential is invisible to the eye - the Little Prince - Despite recent advances in management, patients with acute ST-segment elevation myocardial infarction (STEMI) are still at increased risk for adverse outcomes, even after a timely revascularization.1),2) Therefore, early risk stratification for such patients is of clinical importance. STEMI involves remodeling of the left ventricle (LV); and diseased LV is associated with future adverse outcomes. In this issue of the Journal, Na et al.,3) in their research using 2-dimensional strain technique, demonstrated that global longitudinal strain (GLS) can predict adverse remodeling in patients with STEMI; GLS value, along with left ventricular end-diastolic volume, deceleration time of mitral inflow, and CK-MB level, independently predicted adverse remodeling of the LV, whereas global circumferential strain, net twist, and twist/untwist rate did not. Many studies have reported on the prognostic power of GLS.4),5),6) A strongpoint of this study is the relatively large (n = 208) and homogenous study sample (acute STEMI patients who were treated with a timely successful reperfusion therapy and underwent echocardiographic evaluation for strain analysis within 24 hrs after treatment). In addition, the authors' hypothetical explanation for the data (i.e., GLC, but not global circumferential strain, is a predictor for LV remodeling) in the discussion section of the article seems reasonable. However, this study should not be regarded as the final answer to the many questions and there is skepticism regarding the eye-catching echocardiographic technique. In routine clinical practice, we still resort to mainly visual assessment of myocardial wall motion based on two-dimensional echocardiography when assessing LV performance. Strain analysis is supposed to be objective, however there are many obstacles to its wide application in clinical practice, including the issue of reproducibility, time-consuming off-line analysis, good quality echo-images, which are not always easy to obtain, as well as issues regarding vendor-specific differences: reproducibility issues.6) Despite these limitations, there are copious research data supporting the unique strongpoints of strain analysis, and the current research by Na et al.3) sheds light on strain analysis for early prediction of adverse LV remodeling in STEMI patients and would at least provide a robust background for further investigation to determine the clinical usefulness of the ever-developing echocardiographic technique.

Abstract 15339: Molecular Analysis of Epigenetic Modification Process in Distressed Cardiomyocytes May Explor Indication of Mitral Valve Surgery for Advanced Heart Failure Associated With Non-ischemic Dilated Cardiomyopath

Introduction: Mitral valve (MV) surgery for functional mitral regurgitation (MR) associated with advanced heart failure (HF) is a surgical challenge with surgical indication not clearly established. It was recently reported that the epigenetic modification, such as methylation or acetylation of histone H3, is closely related to functional reversibility of cardiomyocytes in advanced HF. Hypothesis: We herein hypothesized that epigenetic profiles in the left ventricle (LV) may be associated with clinical outcome of MV surgery for non-ischemic dilated cardiomyopathy (NIDCM)-causing advanced HF. Methods: Thirteen patients diagnosed as having NIDCM underwent chordal sparing MV replacement for severe MR associated with low ejection fraction (EF) (&lt;35%) between 2012 and 2015. Intraoperatively biopsied LV tissue was immunohistologically labeled by histone H3 lysine 9 tri-methylation (H3K9me3) and acetylation (H3K9ac), and then the scores ranging from 0 to 12 were assigned as intensity and percentage of positive staining cardiac cell nuclei. Results: Four patients (31%) necessitated left ventricular assist device (LVAD) implantation for persistent low output syndrome post-MV replacement, and one patient died of cardiac failure on day 260. Preoperative factors assessed by routine echocardiogram or right heart catheter study, such as LVEF (26±3 vs 24±6%, p=0.49), LV end-systolic dimension index (159±49 vs 188±58 ml/m2, p=0.42), or mean pulmonary arterial pressure (27±11 vs 22±9mmHg, p=0.42), were not a predictive factor of LVAD implantation post-MV surgery. In contrast, preoperative LV stroke work index (LVSWI) was significantly lower in the patients who had LVAD implantation (13±2 vs 22±7 g·m/m2/beat, p=0.02). In addition, the scores of H3K9me3 and H3K9ac were significantly lower in the patients with LVAD implantation (3.0±0.7 vs 6.5±1.9, p&lt;0.01 and 4.1±0.7 vs 8.9±1.9, p&lt;0.01, respectively) and closely correlated with preoperative LVSWI. Conclusions: Reduced H3K9 methylation and acetylation in cardiomyocytes was closely related to preoperative poor LV performance and represented poor clinical outcome after MV replacement in advanced NIDCM, suggesting that these parameters may be useful factors in determining the surgical indication.

PP.08.22

Objective: Augmentation index (AI) is a well recognized marker of arterial stiffness related to cardiovascular morbidity and mortality. The arterial pulse waveform is the sum of the forward wave generated by left ventricle (LV) and a backward wave reflected from the periphery. The aim of this study was to estimate the relation of AI with hemodynamic indices of LV performance and afterload assessed by impedance cardiography (ICG) in young and middle-aged patients with arterial hypertension (AH). Design and method: This study involved 144 patients (mean age: 45.2 years) with untreated AH. Augmentation index was evaluated by applanation tonometry (SphygmoCor® system) and systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR), stroke index (SI), cardiac index (CI), Heather index (HI), left ventricular ejection time (LVET), systemic vascular resistance index (SVRI), total artery compliance (TAC) by ICG (Niccomo™ device). The analysis included: interquartile comparison in subgroups of AI < 15% (Q1), 15–22% (Q2), 23–29% (Q3), equal or higher than 30% (Q4) and the assessment of correlation between AI and the above ICG variables. Results: The mean AI in the study group was 21.8 ± 13.3%. Gender distribution among quartiles was disproportionate: lower quartile was dominated by men (97.2%) and upper (Q4) - by women (77.6%; p < 0.00001). The subjects in Q4, in comparison with Q1, were older (41.8 vs 39.8 years; p < 0.00001) and characterized with lower height (166.5 vs 180.8 cm; p < 0.00001), HR (68.1 vs 78.8 bpm; p < 0.00001), longer LVET (330.8 vs 287.7 ms; p < 0.00001), higher SI (52.3 vs 45.5 ml/m2; p < 0.05) and HI (14.8 vs 12.1 Ohm*s2; p < 0.05). No significant differences in DBP, CI, SVRI and TAC were identified. Correlation analysis revealed significant associations of AI with age (r = 0.45; p < 0.00001), height (r = -0.53; p < 0.00001); HR (r = −0.37; p < 0.00001); SI (r = 0.28; p < 0.05), LVET (0.43, p < 0.00001) and HI (r = 0.25; p < 0.001). However, in multivariate linear regression analysis the only independent determinants of AI (as dependent variable) were age, height and HR (R2 = 0.57). Conclusions: Our results suggest that the strongest determinants of AI in young and middle-aged hypertensives are age, gender, height and hemodynamic indices of LV performance but not those characterised afterload.