Changes In Left Ventricular Mechanics Research Articles

Impact of aortic valve stenosis on myocardial deformation in different left ventricular levels: A three-dimensional speckle tracking echocardiography study.

Global systolic left ventricular (LV) myocardial function progressively declines as degenerative aortic valve stenosis (AS) progresses. Whether this results in uniformly distributed deformation changes from base to apex has not been investigated. Eighty-five AS patients underwent three-dimensional (3D) echocardiography in this cross-sectional study. Patients were grouped by peak jet velocity into mild (n=32), moderate (n=31), and severe (n=22) AS. 3D speckle tracking derived strain, rotation, twist, and torsion were obtained to assess global LV function and myocardial function at the apical, mid, and basal levels. Global longitudinal strain (GLS) was lower in patients with severe AS (-16.1±2.4% in mild, -15.5±2.5% in moderate, and -13.5±3.0% in severe AS [all p<.01]). Peak basal and mid longitudinal strain (LS), basal rotation and twist from apical to basal level followed the same pattern, while peak apical LS was higher in moderate AS compared to severe AS (all p<.05). In multivariate analyses, lower GLS was particularly associated with male sex, higher body mass index and peak aortic jet velocity, lower basal LS with higher filling pressure (E/e') and LV mass, lower mid LS with higher RWT and presence of AS symptoms, and lower apical LS with male sex and higher systolic blood pressure, respectively (all p<.05). Using 3D speckle tracking echocardiography reveals regional and global changes in LV mechanics in AS related to the severity of AS, LV remodeling and presence of cardiovascular risk factors.

Evaluation of left ventricle systolic functions with 2D strain echocardiography after transcatheter aortic valve replacement in patients with severe aortic stenosis

ObjectiveThere is deterioration in global left ventricular (LV) longitudinal function in patients with severe aortic valve stenosis, and the decrease in LV global longitudinal strain (GLS) is associated with worsening prognosis. The aim of the study is to examine LV mechanical changes with LV strain imaging in addition to routine examination in patients who underwent transcatheter aortic valve replacement (TAVR). MethodsFifty patients who had been scheduled for the TAVR procedure between 2016 and 2018 were enrolled. The patients were evaluated before TAVR, 1 and 6 months after the procedure. The patients’ LV ejection fraction (LVEF), LVGLS, LV mass (LVM), LV mass index (LVMI), relative wall thickness (RWT), and left atrial volume index (LAVI) were calculated with transthoracic echocardiography. The patients’ performance scores were evaluated with Kansas City Cardiomyopathy Questionnaire (KCCQ-12). ResultsTwenty-six patients were female (52%), and the mean ages of patients were 75.30 ± 12.26 years. The mean LVEF of the patients was measured at 54.04 ± 13.48%, 58.10 ± 11.49%, and 59.36 ± 11.85 preprocedure and at first and 6 months, respectively. This increase in LVEF was statistically significant (p < 0.001). The mean LVGLS was measured −15.83 ± 2.78 preprocedure. The means of LVGLS were −18.73 ± 3.49 and −19.87 ± 4.05 at first and 6 months, respectively. Performance scores of patients significantly improved after the procedure (p < 0.001). The significant decreases in LVM, LVMI, RWT, and LAVI at 6 months compared to the preprocedural evaluation (p < 0.001). ConclusionIn severe aortic stenosis with deformation of LV myocardial mechanics, including GLS, a successful TAVR procedure provides a significant improvement in myocardial mechanics in early and midterm follow-up with.

Cardiovascular magnetic resonance-derived left ventricular intraventricular pressure gradients among patients with precapillary pulmonary hypertension.

Precapillary pulmonary hypertension (pPH) affects left ventricular (LV) function by ventricular interdependence. Since LV ejection fraction (EF) is commonly preserved, LV dysfunction should be assessed with more sensitive techniques. Left atrial (LA) strain and estimation of LV intraventricular pressure gradients (IVPG) may be valuable in detecting subtle changes in LV mechanics; however, the value of these techniques in pPH is unknown. Therefore, the aim of our study is to evaluate LA strain and LV-IVPGs from cardiovascular magnetic resonance (CMR) cines in pPH patients. In this cross-sectional study, 31 pPH patients and 22 healthy volunteers underwent CMR imaging. Feature-tracking LA strain was measured on four- and two-chamber cines. LV-IVPGs (from apex-base) are computed from a formulation using the myocardial movement and velocity of the reconstructed 3D-LV (derived from long-axis cines using feature-tracking). Systolic function, both LV EF and systolic ejection IVPG, was preserved in pPH patients. Compared to healthy volunteers, diastolic function was impaired in pPH patients, depicted by (i) lower LA reservoir (36 ± 7% vs. 26 ± 9%, P < 0.001) and conduit strain (26 ± 6% vs. 15 ± 8%, P < 0.001) and (ii) impaired diastolic suction (-9.1 ± 3.0 vs. ‒6.4 ± 4.4, P = 0.02) and E-wave decelerative IVPG (8.9 ± 2.6 vs. 5.7 ± 3.1, P < 0.001). Additionally, 11 pPH patients (35%) showed reversal of IVPG at systolic-diastolic transition compared to none of the healthy volunteers (P = 0.002). pPH impacts LV function by altering diastolic function, demonstrated by an impairment of LA phasic function and LV-IVPG analysis. These parameters could therefore potentially be used as early markers for LV functional decline in pPH patients.

Features of changes in left ventricular mechanics in patients with epicardial obesity

Abstract Currently, there is no single non-invasive marker that can directly assess left ventricular (LV) diastolic function. Untwist of LV contributes to diastolic suction and early filling. Speckle-tracking imaging can be used to diagnose diastolic dysfunction at the preclinical stage. Objective To study the features of changes in the parameters of LV mechanics and their relationship with the levels of serum markers of myocardial fibrosis in patients with epicardial obesity (EO). Materials and methods The study included 125 men with general obesity. All patients underwent transthoracic echocardiography (ECG) to assess the thickness of epicardial adipose tissue (tEAT) as equivalent to visceral obesity, as well as to diagnose diastolic dysfunction (DD) of left ventricle (LV). According to the results of ECG, the patients were divided into 2 groups: EO(+) with epicardial fat thickness (tEAT) ≥7 mm (n=78); EO(−) with (tEAT) &amp;lt;7 mm (n=40). DD LV was detected in 7 patients, who were subsequently excluded from the analysis. Profibrotic markers in blood serum (MMP-3, collagen I, collagen III, TGF-β, VEGFA, PICP) were determined in all patients using enzyme immunoassay. Using speckle-tracking ECG, the mechanics of LV were studied (twist LV, peak twist ratio LV, time to peak twist of LV, peak untwist ratio LV, time to peak untwist of LV). The exclusion criteria were the presence of coronary pathology, arterial hypertension, and type 2 diabetes mellitus. Results In the group of patients with EO(+) statistically significant increase the level of all studied profibrotic markers was revealed. According to the results of speckle-tracking ECG in the EO(+) group an increase peak untwist ratio LV to −125.56 (−141.0; −117.0)deg/s (p=0.003) and an increase time to peak untwist of LV of 469.44 (509.0; 401.0) msec was determined in comparison with the EO(−) group (p=0.03). A weak statistically significant effect of tEAT on the peak untwist ratio LV in EO(+) group was revealed (r=0.28; p=0.03). In addition, there was a significant relationship between peak untwist ratio LV and markers of myocardial fibrosis MMP-3 (r=0.23; p=0.03) and collagen type III (r=0.25; p=0.04). Conclusion Thus, LV unwinding may be a new non-invasive marker of LV DD at the preclinical stage, since this parameter reflects the mechanical aspect of global diastolic function, especially the early phase of diastole. Funding Acknowledgement Type of funding sources: None.

Assessment of Strain Changes in the Triple Layers of Left Ventricle in Normotensive Versus Hypertensive Patients

The phenomenon of left ventricular remodeling caused by hypertension is a well-known affair that can be evaluated through echocardiography techniques. In recent decade, modern echocardiographic methods such as speckle tracking echocardiography have been used to evaluate left ventricular mechanical changes in hypertensive conditions. The evaluation of the strain index as an important part of the evaluation of the ventricular wall in various ventricular layers has been highly regarded in hypertensive patients. In this regard, the left global ventricular longitudinal strain (GLS) especially in the three ventricular wall layers can strongly predict mortality and morbidity of cardiovascular disease. Given that hypertensive disease is one of the most important risk factors for the development of heart failure and systolic and diastolic cardiovascular dysfunction, even in cases with preserved left ventricular ejection fraction, the exact determination of ventricular strain changes in various layers in hypertensive states would be beneficial for preventing hypertensive cardiomyopathy. In a cross-sectional study, we assessed strain changes in the triple layers of the ventricular wall in hypertensive and normotensive individuals with presence or absence of left ventricular diastolic dysfunction. In this study, both global longitudinal strain (GLS) and global circumferential strain (GCS) indices in endocardial, myocardial and epicardial layers were evaluated. We also considered the effect of diastolic ventricular dysfunction as an important confounder with the effect of hypertension on the ventricular strain. An important finding of this study was the significant effect of hypertension on reducing GLS and GCS in mid myocardial and epicardial layers in the presence of left ventricular diastolic dysfunction. At first, in case of hypertension, the presence of diastolic dysfunction in reducing the strain of the left ventricular wall seems to be necessary as a trigger factor; thus in hypertensive cases with preserved diastolic function, the strain change in left ventricular wall may not be evident. Secondly, reduction in the ventricular wall strain in the endocardial layer was not revealed but it seems that the exacerbation of uncontrolled hypertension may also lead to endocardial involvement as shown by prior studies. In total, proper control of blood pressure in patients with a history of hypertension, especially in the field of left ventricular diastolic dysfunction will improve the function of the left ventricular wall and thus improve the prognosis of these patients.Disturbance in left ventricle wall layers in the field of hypertension has been studied and confirmed in several studies, although the effective role of diastolic dysfunction has been studied less. For instance, in a study by Tadic et al., GLS was significantly lower in hypertensive than in normotensive patients (1). In Navarini et al study, although no difference was found in left ventricular volume or ejection fraction, both GLS and GCS reduced significantly in hypertensive status (2). In a study by Craciunescu et al, LV mass was higher and both the GLS and GCS parameters were significantly lower in the uncontrolled hypertension group than in patients with controlled hypertension (3). In a study by Nagata et al., the values of GLS and GCS in the endocardial layer were higher than the other layers, and this could justify the preservation of the strain in the field of hypertension in the endocardial layer (4). Finally, in a study by Sharif et al, patients with diastolic dysfunction experienced a relative decrease in GLS in all three layers of myocardial infarction, compared with those without diastolic dysfunction, which was consistent with our findings (5). What can be emphasized as the final result is that prolonged and uncontrolled hypertension with an effect on cell growth as well as cardiomyocyte fibrosis through the secretion of inflammatory and growth factors leading left ventricular hypertrophy can reduce strain in various ventricular wall layers particularly in myocardial and epicardial layers. Of course, the role of the presence of diastolic ventricular dysfunction is highly indicative in these changes.

102 Different mechanics of septal and lateral walls and their effects on left ventricular ejection fraction in patients with left bundle-branch block

Abstract Funding Acknowledgements Karolina Kupczynska was supported by research grant awarded by the Club 30 of the Polish Cardiac Society Background Left bundle branch block (LBBB) impairs left ventricular (LV) mechanics and can lead to systolic dysfunction. However, LV mechanical changes that differentiate LBBB patients with preserved and reduced LV ejection fraction (LVEF) remain to be clarified. Purpose To measure myocardial work (MWI) and myocardial work efficiency (MWE) of the septal and LV lateral wall in patients with LBBB and various degrees of LV dysfunction using non-invasive strain-derived method. Methods Fifty-eight LBBB patients without coronary artery disease (mean age 65 ± 13 years, 60% male) were divided into 4 groups based on their LVEF according to current recommendations for cardiac chamber quantification (figure A): normal (n= 25), mildly (n= 16), moderately (n= 11), and severely (n= 6) reduced LVEF. Septal and lateral wall MWI and MWE were estimated by LV pressure-strain loop obtained by echocardiography. Results Both MWI (787 mmHg%, 95% CI 651-924 vs 1956 mmHg%, 95% CI 1758-2154; p &amp;lt; 0.0001) and MWE (71%, 95% CI 66-76 vs 85%, 95% CI 82-87; p = 0.0001) were lower in the septum than in the lateral wall. There was a progressive decrease in septal MWI and MWE with the worsening of LVEF (figure B). Conversely, MWI and MWE of the lateral wall were preserved in patients with normal, mildly and moderately reduced LVEF groups. A significant reduction of MWI and MWE in the lateral wall was detected only in patients with severely reduced LVEF (figure C). Conclusion In patients with LBBB, impairment in septal myocardial work escalates according to LVEF loss. Septal dysfunction was compensated by the effective myocardial work of the lateral wall in patients with normal, mildly and moderately reduced LVEF. Mechanical dysfunction of the lateral wall was associated with severe reduction of LVEF. Abstract 102 Figure.

Changes in Left Ventricular Mechanics After Sleeve Gastrectomy.

The aim of this study was to examine echocardiographic parameters of left ventricle (LV) mechanics in obese patients before and after sleeve gastrectomy (SG). Twenty-five obese individuals submitted to laparoscopic SG were enrolled in this study. Echocardiography was performed before and after the procedure, and left ventricle mechanics were evaluated by speckle tracking imaging. Before surgery, altered global longitudinal strain (GLS) values were present in 56% of the patients. In a mean follow-up of 3.6 ± 0.5 months after surgery, there was an increase in GLS values (from 17.4 ± 3.2 to 19.3 ± 2.7%, P = 0.01). There was an inverse correlation between the absolute values of GLS in the preoperative period and the variation in the GLS at follow-up (r = 0.577, P = 0.002). Measurements of global circumferential strain (GCS), global radial strain (GRS), and LV twist were normal preoperatively and did not change after surgery. Altered global longitudinal strain values were common in young obese patients. Sleeve gastrectomy increased global longitudinal strain even in the early postoperative phase without promoting changes in global radial strain, global circumferential strain, and left ventricle twist measurements.

Unaltered left ventricular mechanics and remodelling after 12 weeks of resistance exercise training - a longitudinal study in men.

Previous longitudinal studies suggest that left ventricular (LV) structure is unaltered with resistance exercise training (RT) in young men. However, evidence from aerobic exercise training suggests that early changes in functional LV wall mechanics may occur prior to and independently of changes in LV size, although short-term changes in LV mechanics and structural remodelling in response to RT protocols have not been reported. Therefore, the purpose of this study was to examine the effects of RT on LV mechanics in healthy men performing 2 different time-under-tension protocols. Forty recreationally trained men (age: 23 ± 3 years) were randomized into 12 weeks of whole-body higher-repetition RT (20-25 repetitions/set to failure at ∼30%-50% 1 repetition maximum (1RM); n = 13), lower-repetition RT (8-12 repetitions/set to failure at ∼75%-90% 1RM; n = 13), or an active control period (n = 14). Speckle tracking echocardiography was performed at baseline and following the intervention period. Neither RT program altered standard measures of LV volumes (end-diastolic volume, end-systolic volume, or ejection fraction; P > 0.05) or indices of LV mechanics (total LV twist, untwisting rate, twist-to-shortening ratio, untwisting-to-twist ratio, or longitudinal strain; P > 0.05). This is the first longitudinal study to assess both LV size and mechanics after RT in healthy men, suggesting a maintenance of LV size and twist mechanics despite peripheral muscle adaptations to the training programs. These results provide no evidence for adverse LV structural or functional remodelling in response to RT in young men and support the positive role of RT in the maintenance of optimal cardiovascular function, even with strenuous RT.

The Effects of Surgical Myectomy on Left Ventricular Mechanics in Patients with Hypertrophic Obstructive Cardiomyopathy

Background: Hypertrophic obstructive cardiomyopathy (HOCM) is an inherited disorder, characterized by left ventricle outflow tract obstruction. We performed this study to investigate the changes in left ventricular mechanics after surgical myectomy in patients with HOCM. Materials and methods: We enrolled 15 patients with HOCM referred to surgical myectomy according to the recommendation of American Heart Association. All patients underwent transthoracic 2D speckle-tracking echocardiography to measure cardiac dimensions and mechanics before and after surgery. statistical analyses were performed using GraphPad Instat and MedCalc software. Results: Following myectomy, all patients reported improved symptoms and increased functional capacity. Conventional echocardiographic measurements showed that surgical myectomy significantly decreased left atrial volume index (r=0.83, p˂0.0001), interventricular septum thickness (p˂0.0001, r=0.79), left-ventricular mass index (p˂0.0001, r=0.49) and resting left-ventricular outflow tract pressure gradient (p˂0.0001, r=-0.03). In terms of leftventricular function, we observed significant decreases in fractional shortening (r=0.16, p˂0.0001) and ejection fraction (p=0.01, r=-0.04) after the procedure in comparison to baseline functional data. We further significant postoperative reductions in terms of average circumferential strain (p˂0.0001, r=0.49), basal rotation (p=0.03, r=0.97), apical rotation (p˂0.0001, r=0.94) and LV twist (p˂0.0001, r=0.96). However, no significant changes were observed after myectomy in terms of most longitudinal strain and left ventricular synchrony measures. Conclusion: Surgical myectomy improves symptoms, relieves left ventricular outflow tract obstruction and decreases left atrial volume index in patients with HOCM, but shows no significant changes in LV longitudinal strain and LV synchrony measures. Future studies should employ a larger sample size and more sensitive methods of synchrony detection.

Left bundle branch block: from cardiac mechanics to clinical and diagnostic challenges.

Left bundle branch block (LBBB) results in an altered pattern of left ventricular (LV) activation and subsequent contraction, causing remarkable changes in LV mechanics, perfusion and workload and ultimately leading to pathologic cardiac remodelling. Clinical and diagnostic notions about the LBBB phenomenon had evolved from just an electrocardiographic pattern to a critically important finding affecting diagnostic and clinical management of many patients and adversely influencing their outcomes. Recent advances in imaging techniques significantly improved the assessment of patients with LBBB and provided additional insights into pathophysiological mechanisms of LV remodelling. In the current review we summarized currently available data on the LBBB epidemiology, diagnosis, its impact on clinical management and prognosis, and the role and place of various imaging modalities in assessing cardiac mechanics and perfusion abnormalities, as well as their potential implications for diagnostic and treatment strategies.

Acute Changes in Left Ventricular Mechanics During Voluntary Apnea

IntroductionObstructive sleep apnea (OSA) is characterized by intermittent apneic events and is associated with hypertension, sudden cardiac death, and acute cardiac infarction. During an apneic event asphyxia‐induced increases in sympathetic nerve activity result in subsequent increases in arterial blood pressure and systemic vascular resistance. However, it is currently unknown how cardiac mechanics are acutely impacted by these systemic responses to an apneic event. Therefore, the purpose of the present study was to evaluate changes in left ventricular systolic and diastolic function during voluntary apnea. We hypothesized that during voluntary apnea left ventricular systolic and diastolic function would be compromised in parallel with increases in arterial blood pressure and myocardial work.Methods9 healthy men (23 ± 3 yrs) were recruited for the study. Subjects performed multiple voluntary breath holds at functional residual capacity with 3–5 minutes in between. Beat‐by‐beat blood pressure, heart rate and stroke volume were measured continuously. End‐tidal CO2 was measured at end‐apnea. Tissue Doppler echocardiography was used to measure tissue velocities, and myocardial deformation via strain (S), and strain rate (SR) at the mid‐interventricular septum across 3 continuous cardiac cycles at baseline and end‐apnea.ResultsSystolic blood pressure (Δ13.8 ± 8.4 mmHg, p&lt;0.01), mean arterial pressure (Δ12.4 ± 7.0 mmHg, p&lt;0.01), and rate pressure product (Δ8.4 ± 5.6 mmHg × bpm 10−2, p&lt;0.01) significantly increased with apnea, but not stroke volume (Δ3.3 ± 8.1 ml, p=0.26). Peak longitudinal systolic (Δ −0.56 ± 0.69 cm s−1, p=0.04) and early LV filling (Δ −2.32 ± 2.04 cm s−1, p&lt;0.01) myocardial velocities were significantly decreased during the apnea. Longitudinal Systolic S (Δ −2.17 ± 2.36%, p=0.02) and SR (Δ −0.20 ± 0.29 1/s, p=0.07) were significantly decreased during the apnea. Early LV filling SR was not different compared to baseline with apnea (p=0.41).ConclusionConsistent with our hypotheses, left ventricular deformation was significantly impaired with voluntary apnea. These data suggest that the systemic increases in arterial pressure during voluntary apnea have an adverse effect on left ventricular systolic mechanics.

Left Ventricular Rotational Mechanics in Preterm Infants Less Than 29 Weeks’ Gestation over the First Week after Birth

There is a paucity of data on left ventricular (LV) rotational physiology, twist, and torsional mechanics in preterm infants. The principal aims of the present study were to assess the feasibility and reproducibility of measuring LV rotation, twist, and torsion in preterm infants (<29 weeks' gestation) using two-dimensional speckle-tracking echocardiography and to examine the changes in those parameters over the first week after birth. This was a prospective observational study involving preterm infants <29 weeks' gestation. Echocardiographic evaluations were performed on days 1, 2, and 5 to 7 after delivery. LV basal and apical rotation, LV twist, LV twist rate (LVTR), and LV untwist rate (LVUTR) were measured from the basal and apical short-axis parasternal views and calculated using two-dimensional speckle-tracking echocardiography. Torsion was also calculated by normalizing LV twist to LV end-diastolic length. One-way repeated-measures analysis of variance was used to compare values across the three time points. Intra- and interobserver reproducibility were assessed using Bland-Altman analysis and the intraclass correlation coefficient. Fifty-one infants with a mean ± SD gestational age of 26.8 ± 1.5 weeks and a mean birth weight of 945 ± 233 g were included. There was high intra- and interobserver reproducibility for basal and apical rotation, LV twist, and LV torsion, with intraclass correlation coefficients ranging from 0.78 to 0.96 (P < .001 for all). Intra- and interobserver intraclass correlation coefficients for LVTR and LVUTR ranged from 0.70 to 0.88 (P < .001 for all). Apical rotation remained constant over the first week of age in a positive counterclockwise fashion (11.8 ± 5.0° vs 12.1 ± 6.1° vs 11.7 ± 8.3°, P = .92). Basal rotation changed from counterclockwise on day 1 to clockwise on day 7 (median, 5.5° [interquartile range, -0.3° to 8.3°] vs 4.0 [interquartile range, -4.7° to 7.2°] vs -4.5° [interquartile range, -5.8° to -2.3°], P < .001), with resultant net increases in twist and torsion (P < .05). There was no change in LVTR (P = .60), but LVUTR increased across the same time period (P = .01). Assessment of twist, LVTR, and LVUTR is feasible in preterm infants, with acceptable reproducibility. There are increases in LV twist and torsion in addition to LVUTR, suggesting changes in LV mechanics during the first week of age.

Integración de la imagen mecánica, estructural y eléctrica para entender la respuesta a la terapia de resincronización cardiaca

Introduction and objectivesThere is extensive controversy exists on whether cardiac resynchronization therapy corrects electrical or mechanical asynchrony. The aim of this study was to determine if there is a correlation between electrical and mechanical sequences and if myocardial scar has any relevant impact. MethodsSix patients with normal left ventricular function and 12 patients with left ventricular dysfunction and left bundle branch block, treated with cardiac resynchronization therapy, were studied. Real-time three-dimensional echocardiography and electroanatomical mapping were performed in all patients and, where applicable, before and after therapy. Magnetic resonance was performed for evaluation of myocardial scar. Images were postprocessed and mechanical and electrical activation sequences were defined and time differences between the first and last ventricular segment to be activated were determined. Response to therapy was defined as a reduction in left ventricular end-systolic volume ≥ 15% after 12 months of follow-up. ResultsGood correlation between electrical and mechanical timings was found in patients with normal left ventricular function (r2 = 0.88; P = .005) but not in those with left ventricular dysfunction (r2 = 0.02; P = not significant). After therapy, both timings and sequences were modified and improved, except in those with myocardial scar. ConclusionsDespite a close electromechanical relationship in normal left ventricular function, there is no significant correlation in patients with dysfunction. Although resynchronization therapy improves this correlation, the changes in electrical activation may not yield similar changes in left ventricular mechanics particularly depending on the underlying myocardial substrate.Full English text available from: www.revespcardiol.org\\en

Integration of Mechanical, Structural and Electrical Imaging to Understand Response to Cardiac Resynchronization Therapy

Introduction and objectivesThere is extensive controversy exists on whether cardiac resynchronization therapy corrects electrical or mechanical asynchrony. The aim of this study was to determine if there is a correlation between electrical and mechanical sequences and if myocardial scar has any relevant impact. MethodsSix patients with normal left ventricular function and 12 patients with left ventricular dysfunction and left bundle branch block, treated with cardiac resynchronization therapy, were studied. Real-time three-dimensional echocardiography and electroanatomical mapping were performed in all patients and, where applicable, before and after therapy. Magnetic resonance was performed for evaluation of myocardial scar. Images were postprocessed and mechanical and electrical activation sequences were defined and time differences between the first and last ventricular segment to be activated were determined. Response to therapy was defined as a reduction in left ventricular end-systolic volume ≥ 15% after 12 months of follow-up. ResultsGood correlation between electrical and mechanical timings was found in patients with normal left ventricular function (r2 = 0.88; P = .005) but not in those with left ventricular dysfunction (r2 = 0.02; P = not significant). After therapy, both timings and sequences were modified and improved, except in those with myocardial scar. ConclusionsDespite a close electromechanical relationship in normal left ventricular function, there is no significant correlation in patients with dysfunction. Although resynchronization therapy improves this correlation, the changes in electrical activation may not yield similar changes in left ventricular mechanics particularly depending on the underlying myocardial substrate.

Temporal changes in left ventricular mechanics: impact of bed rest and exercise (884.23)

BACKGROUND: The use of more sensitive and specific echocardiographic techniques, such as speckle‐tracking imaging, may address the current limitations of conventional cardiac imaging techniques to provide insight into the magnitude and time course of cardiac deconditioning following spaceflight or head‐down tilt bed rest (HDTBR). METHODS: Speckle‐tracking assessment of longitudinal, radial, and circumferential strain and twist was used to evaluate the impact of 70 days of HDTBR (n=7) and HDTBR + exercise (n=11) on temporal changes in left ventricular (LV) mechanics. Echocardiograms were performed before (BR‐2), during (BR31, 70), and following (BR+4h) HDTBR. Repeated measures ANOVA was used to evaluate the effect of HDTBR on cardiac variables in control and exercise subjects. RESULTS: After sedentary HDTBR, longitudinal (‐19.0 ± 1.8% vs. ‐14.9 ± 2.4%) and radial (15.0 ± 1.9% vs. 11.3 ± 2.2%) strain and twist (18.0 ± 4.0° vs. 17.0 ± 3.6°) were significantly impaired. In contrast, exercise preserved LV mechanics, and there were non‐significant improvements from BR‐2 to BR70 in longitudinal strain (‐18.7 ± 1.5% vs. ‐20.4 ± 2.7%), radial strain (13.2 ± 2.4% vs. 14.2 ± 1.6%), and twist (16.3 ± 3.6° vs. 18.6 ± 5.9°). CONCLUSIONS: Speckle‐tracking echocardiography provides important new insight into temporal changes in LV mechanics during disuse and exercise training.Grant Funding Source: NASA Johnson Space Center’s Human Research Program

Effects of Percutaneous Balloon Mitral Valvuloplasty on Left Ventricular Deformation in Patients with Isolated Severe Mitral Stenosis: A Speckle-Tracking Strain Echocardiographic Study

Previous studies have reported abnormal left ventricular (LV) contraction in patients with mitral stenosis (MS). The aim of this study was to explore the serial changes in LV mechanics in patients with severe MS undergoing balloon mitral valvuloplasty (BMV) to understand the reversibility and determinants of abnormal LV contractile function. Fifty-seven patients with severe MS and 19 healthy controls underwent echocardiographic examinations, including two-dimensional speckle-tracking-based LV global longitudinal strain (GLS) and global circumferential strain measurements. In patients with MS, the same measurements were repeated 72 hours after BMV. In comparison with controls, patients with MS had faster heart rates and lower LV end-diastolic volumes and LV ejection fractions (P= .008). The magnitudes of both GLS and global circumferential strain were reduced in patients with MS (P < .001 for both), with 48 patients (84.2%) having GLS below the 25th percentile of controls. BMV resulted in significant improvements in GLS and global circumferential strain (-14.6 ± 3.3% vs -17.8 ± 3.5% and -20.0 ± 5.0% vs -22.5 ± 4.6%, respectively, P < .005 for both). On multivariate analysis, left atrial volume, mean transmitral gradient, and LV end-diastolic volume were independently correlated with baseline GLS, whereas increment in LV end-diastolic volume was the only determinant of increased GLS after BMV. LV deformation is reduced in patients with severe MS and is related to the hemodynamic severity of MS. BMV results in rapid improvement of LV deformation, which is correlated with serial improvement in LV diastolic loading. These findings suggest that reduced LV diastolic filling rather than an irreversible myocardial structural abnormality contributes predominantly to reduced LV mechanical performance in patients with MS.

Left ventricular strain distribution in healthy dogs and in dogs with tachycardia-induced dilated cardiomyopathy

BackgroundRecently, left ventricular (LV) strain distribution pattern has been assessed in several cardiac disease states. Tachycardia-induced cardiomyopathy (TIC) is an animal model of non-ischemic cardiomyopathy well characterized in terms of global LV dysfunction but with poor understanding of regional variability in LV function. We hypothesized that TIC induces specific changes in LV strain distribution pattern.MethodsTwenty five adult mongrel conscious dogs were trained to lie down calmly for echocardiography. In seven selected dogs, we implanted pacing system for TIC induction under general anesthesia. We measured LV geometry and function, strains, and torsion before and after the development of TIC in awake non-sedated state.ResultsIn 25 healthy dogs, all three types of normal strain significantly increased from base to apex (p <0.05), while a definite and recognizable twist could be measured due to presence of shear strain. In 7 dogs with TIC, marked changes in LV mechanics occurred throughout the cardiac cycle, resulting in decrease of strain (p <0.001), twist (p <0.05), and negative peak twist rate (p <0.05). Interestingly, the relative decrease of strain due to TIC was more pronounced in the apex (p < 0.001), with the radial strain decreasing the most (p < 0.05).ConclusionTIC is accompanied by decreased systolic LV strain and twist deformation, as well as loss of early diastolic recoil. In addition, the decrease of strain was more profound in the apex. This “reverse” distribution of LV strain may help us understand LV dysfunction in the presence of nonischemic etiology.

Natural History of Left Ventricular Mechanics in Transplanted Hearts: Relationships With Clinical Variables and Genetic Expression Profiles of Allograft Rejection

The aim of this study was to explore the temporal evolution of left ventricular (LV) mechanics in relation to clinical variables and genetic expression profiles implicated in cardiac allograft function. Considerable uncertainty exists regarding the range and determinants of variability in LV systolic performance in transplanted hearts (TXH). Fifty-one patients (mean age 53 ± 12 years; 37 men) underwent serial assessment of echocardiograms, cardiac catheterization, gene expression profiles, and endomyocardial biopsy data within 2 weeks and at 3, 6, 12, and 24 months after transplantation. Two-dimensional speckle-tracking data were compared between patients with TXH and 37 controls (including 12 post-coronary artery bypass patients). Post-transplantation mortality and hospitalizations were recorded with a median follow-up period of 944 days. Global longitudinal strain (LS) and radial strain remained attenuated in patients with TXH at all time points (p < 0.001 and p = 0.005), independent of clinical rejection episodes. Failure to improve global LS at 3 months (≥ 1 SD) was associated with higher incidence of death and cardiac events (hazard ratio: 5.92; 95% confidence interval: 1.96 to 17.91; p = 0.049). Multivariate analysis revealed gene expression score as the only independent predictor of global LS (R(2) = 0.53, p = 0.005), with SEMA7A gene expression having the highest correlation with global LS (r = -0.84, p < 0.001). Speckle tracking-derived LV strains are helpful in estimating the burden of LV dysfunction in patients with TXH that evolves independent of biopsy-detected cellular rejection. Failure to improve global LS at 3 months after transplantation is associated with a higher incidence of death and cardiac events. Serial changes in LV mechanics correlate with peripheral blood gene expression profiles and may affect the clinical assessment of long-term prognosis in patients with TXH.

Enhancement of ventricular mechanics following bidirectional superior cavopulmonary anastomosis in patients with single ventricle.

Seventeen consecutive patients undergoing bidirectional cavopulmonary anastomosis (BDCPA) using normothermic, noncardioplegic, cardiopulmonary bypass were studied preoperatively and early postoperatively (12.2 days) using transthoracic echocardiographic techniques. The purpose of the study was to assess the changes in left ventricular mechanics associated with the change in blood flow related to the BDCPA. Of the 17 patients, pulmonary atresia and tricuspid stenosis was present in 7, tricuspid atresia in 6, double inlet left ventricle in 3, and severe pulmonic stenosis with straddling of the tricuspid valve in 1. All other forms of single ventricle type anatomy and other patients undergoing BDCPA were excluded for the purposes of this study. The mean left ventricular end-diastolic volume index fell from 120 mL/m2 to 91.1 mL/m2 (p < 0.05). Similarly the left ventricular end-systolic volume index fell from 55.8 mL/m2 to 42.3 mL/m2, respectively (p < 0.05). The stroke volume index also fell from 64.5 mL/m2 to 48.8 mL/m2. Left ventricular ejection fraction was preserved and was unchanged in every patient. It was concluded that BDCPA, performed as described above, preserves left ventricular function and that the systolic and diastolic volumes as well as the stroke volume are significantly decreased as evidence of improvement of left ventricular mechanics. The continued use of the BDCPA either as a definitive procedure or as a staged procedure in preparation for total cavopulmonary connection is therefore endorsed.

Abstract 4700: Changes in Left Ventricular Myocardial Strain after Aortic Valve Replacement: Comprehensive 2-Dimensional Speckle Tracking Strain Imaging Assessment

Background: In patients with severe aortic stenosis and preserved left ventricular (LV) ejection fraction (EF), the presence of subtle left ventricular (LV) dysfunction may be misdiagnosed by the standard methods. Two-dimensional speckle tracking strain imaging enables multidirectional assessment of LV myocardial strain. Objectives: To evaluate the presence of subtle LV dysfunction in patients with severe aortic stenosis by using 2-dimensional speckle tracking imaging and the recovery of myocardial function after aortic valve replacement (AVR). Methods: Changes in radial, circumferential and longitudinal strain/strain rate of the LV were evaluated by using 2-dimensional speckle tracking imaging in 100 severe aortic stenosis patients after AVR. Radial and circumferential strain/strain rate were assessed at mid ventricular short axis level of the LV. Longitudinal strain/strain rate were evaluated at the conventional 2-, 4-chambers and long-axis apical views of the LV. These LV functional parameters were compared to conventional LVEF. Results: After AVR (median follow-up 5.3 months), the aortic valve area significantly increased (from 0.8 ± 0.2 cm 2 to 1.6 ± 0.5 cm 2 , p&lt;0.001) together with a significant decrease in the maximal transaortic pressure gradient (from 72 ± 21 mmHg to 22 ± 9 mmHg, p&lt;0.001). In addition, a significant regression of LV mass index was observed (from 154 ± 48 g/m 2 to 132 ± 44 g/m 2 , p&lt;0.001). The LVEF remained unchanged at follow-up whereas a significant improvement of LV longitudinal and circumferential shortening was observed (Table ). Conclusions: In severe aortic stenosis patients, impaired LV longitudinal and circumferential shortening exist although preserved LVEF. After AVR, myocardial strain improves significantly in these two directions. Two-dimensional speckle tracking strain imaging enables an early detection of these subtle changes in LV performance. Changes in LV mechanics after AVR