Intraventricular Mechanical Dyssynchrony Research Articles

Left bundle branch pacing preserved left ventricular myocardial work in patients with bradycardia.

Left bundle branch pacing (LBBP) is an emerging physiological pacing modality. Left ventricular (LV) myocardial work (MW) incorporates afterload and LV global longitudinal strain to estimate global and segmental myocardial contractility. However, the effect of LBBP on LV MW remains unknown. This study aimed to evaluate the impact of LBBP on LV MW in patients receiving pacemaker for bradyarrhythmia. We prospectively enrolled 70 bradycardia patients with normal LV systolic function receiving LBBP (n = 46) and non-selective His-bundle pacing (NS-HBP) (n = 24). For comparative analysis, patients receiving right ventricular pacing (RVP) (n = 16) and control subjects (n = 10) were enrolled. Two-dimensional speckle tracking echocardiography was performed. The LV pressure-strain loop was non-invasively constructed to assess global LV MW. After 6-month follow-up, LBBP group (with >40% ventricular pacing during 6 months) had shorter peak strain dispersion (PSD) compared with RVP group, and higher LV global longitudinal strain compared with RVP group and NS-HBP group, but had no difference in left intraventricular mechanical dyssynchrony, including septal-to-posterior wall motion delay and PSD, compared with NS-HBP group. During ventricular pacing, LBBP group had higher global MW index (GWI) (2,189 ± 527 vs. 1,493 ± 799 mmHg%, P = 0.002), higher global constructive work (GCW) (2,921 ± 771 vs. 2,203 ± 866 mmHg%, P = 0.009), lower global wasted work (GWW) (211 ± 161 vs. 484 ± 281 mmHg%, P < 0.001) and higher global MW efficiency (GWE) (91.4 ± 5.0 vs. 80.9 ± 8.3%, P < 0.001) compared with RVP group, and had lower GWW (211 ± 161 vs. 406 ± 234 mmHg%, P < 0.001) and higher GWE (91.4 ± 5.0 vs. 86.4 ± 8.1%, P < 0.001) compared with NS-HBP group. In this study we found that in patients with mid-term (6-month) high ventricular pacing burden (>40%), LBBP preserved more LV MW compared with NS-HBP and RVP. Further studies are warranted to assess the association between LV MW and long-term clinical outcomes in LBBP with high ventricular pacing burden.

Relationship between intraventricular mechanical dyssynchrony and left ventricular systolic and diastolic performance: An in vivo experimental study.

Left ventricular mechanical dyssynchrony (LVMD) refers to the nonuniformity in mechanical contraction and relaxation timing in different ventricular segments. We aimed to determine the relationship between LVMD and LV performance, as assessed by ventriculo-arterial coupling (VAC), LV mechanical efficiency (LVeff ), left ventricular ejection fraction (LVEF), and diastolic function during sequential experimental changes in loading and contractile conditions. Thirteen Yorkshire pigs submitted to three consecutive stages with two opposite interventions each: changes in afterload (phenylephrine/nitroprusside), preload (bleeding/reinfusion and fluid bolus), and contractility (esmolol/dobutamine). LV pressure-volume data were obtained with a conductance catheter. Segmental mechanical dyssynchrony was assessed by global, systolic, and diastolic dyssynchrony (DYS) and internal flow fraction (IFF). Late systolic LVMD was related to an impaired VAC, LVeff , and LVEF, whereas diastolic LVMD was associated with delayed LV relaxation (logistic tau), decreased LV peak filling rate, and increased atrial contribution to LV filling. The hemodynamic factors related to LVMD were contractility, afterload, and heart rate. However, the relationship between these factors differed throughout the cardiac cycle. LVMD plays a significant role in LV systolic and diastolic performance and is associated with hemodynamic factors and intraventricular conduction.

Does types of atrial fibrillation matter in the impairment of global and regional left ventricular mechanics and intra-ventricular dyssynchrony?

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia, which is associated with cardiac dysfunction. This study aimed to compare the impairment severity of left ventricular strain and intra-ventricular dyssynchrony using echocardiography-derived velocity vector imaging in patients with different types of AF without heart failure. 168 non-valvular AF patients with normal left ventricular ejection fraction (98 paroxysmal AF patients and 70 persistent AF patients) and 86 healthy control subjects were included in this study. Regional and global left ventricular longitudinal and circumferential strain were measured. Time to regional peak longitudinal strain was measured and the standard deviation of all 12 segments (SDT-S) was used as a measure of intra-ventricular dyssynchrony. Significantly lower GLS (-18.71 ± 3.00% in controls vs. -17.10 ± 3.01% in paroxysmal AF vs. -12.23 ± 3.25% in persistent AF, P < 0.05) and GCS (-28.75 ± 6.34% in controls vs. -24.43 ± 6.86% in paroxysmal AF vs. -18.46 ± 6.42% in persistent AF, P < 0.01) were observed in either persistent AF subjects or paroxysmal AF subjects compared with healthy control subjects (P < 0.05). The impairment was much worse in persistent AF subjects compared with paroxysmal AF subjects (P < 0.001). Intraventricular dyssynchrony was found in both persistent AF patients and paroxysmal AF patients, and it's worse in persistent AF patients (52 ± 18 ms in controls, 61 ± 17 ms in paroxysmal AF, and 70 ± 28 ms in persistent AF, P < 0.05). Multivariate regression analysis revealed AF types were independent risk factors of GLS, GCS, and intraventricular dyssynchrony. AF types were not only associated with impaired longitudinal and circumferential left ventricle mechanics but also intra-ventricular mechanical dyssynchrony. Worse systolic mechanics and intra-ventricular dyssynchrony were found in patients with persistent AF compared with these in patients with paroxysmal AF.

Chronically altered ventricular activation causes pro-arrhythmic cardiac electrical remodelling in the chronic AV block dog model.

Altered ventricular activation (AVA) causes intraventricular mechanical dyssynchrony (MD) and impedes contraction, promoting pro-arrhythmic electrical remodelling in the chronic atrioventricular block (CAVB) dog. We aimed to study arrhythmogenic and electromechanical outcomes of different degrees of AVA. Following atrioventricular block, AVA was established through idioventricular rhythm (IVR; n = 29), right ventricular apex (RVA; n = 12) pacing or biventricular pacing [cardiac resynchronization therapy (CRT); n = 10]. After ≥3 weeks of bradycardic remodelling, Torsade de Pointes arrhythmia (TdP) inducibility, defined as ≥3 TdP/10 min, was tested with specific IKr-blocker dofetilide (25 μg/kg/5 min). Mechanical dyssynchrony was assessed by echocardiography as time-to-peak (TTP) of left ventricular (LV) free-wall minus septum (ΔTTP). Electrical intraventricular dyssynchrony was assessed as slope of regression line correlating intraventricular LV activation time (AT) and activation recovery interval (ARI). Under sinus rhythm, contraction occurred synchronous (ΔTTP: -8.6 ± 28.9 ms), and latest activated regions seemingly had slightly longer repolarization (AT-ARI slope: -0.4). Acute AV block increased MD in all groups, but following ≥3 weeks of remodelling IVR animals became significantly more TdP inducible (19/29 IVR vs. 5/12 RVA and 2/10 CRT, both P < 0.05 vs. IVR). After chronic AVA, intraventricular MD was lowest in CRT animals (ΔTTP: -8.5 ± 31.2 vs. 55.80 ± 20.0 and 82.7 ± 106.2 ms in CRT, IVR, and RVA, respectively, P < 0.05 RVA vs. CRT). Although dofetilide steepened negative AT-ARI slope in all groups, this heterogeneity in dofetilide-induced ARI prolongation seemed least pronounced in CRT animals (slope to -0.8, -3.2 and -4.5 in CRT, IVR and RVA, respectively). Severity of intraventricular MD affects the extent of electrical remodelling and pro-arrhythmic outcome in the CAVB dog model.

Two-dimensional speckle tracking echocardiography detected interventricular dyssynchrony predicts exercise capacity and disease severity in pre-capillary pulmonary hypertension.

BackgroundRight ventricular (RV) intraventricular mechanical dyssynchrony detected by two-dimensional speckle tracking echocardiography (2D-STE) has been reported to be correlated with a decrease in RV contractile efficiency in pulmonary hypertension (PH) patients, while little attention has been paid to biventricular dysfunction. Therefore, we aimed to evaluate the predictive value of 2D-STE detected interventricular dyssynchrony for exercise capacity and disease severity in patients with pre-capillary PH (PcPH).MethodsConventional transthoracic echocardiography, 2D-STE and cardiopulmonary exercise tests (CPETs) were performed in all participants. Intra- and interventricular dyssynchrony were calculated as the standard deviation (SD) of the time intervals corrected for heart rate between QRS onset and peak longitudinal strain. Multivariate linear regression analyses were performed to identify independent predictors of peak oxygen consumption (PVO2) during the CPET. Multivariable logistical regression modeling was used to analyze the associations between interventricular dyssynchrony and risk assessment.ResultsSixty-six PcPH patients were consecutively recruited (19 male and 47 female, average 35 years old). WHO functional class, N-terminal pro-brain natriuretic peptide (BNP) and body mass index were included as independent predictors in the first multivariate regression analysis of clinical data without echocardiographic parameters (Model-1, r2=0.423, P<0.001). We subsequently added conventional echocardiographic parameters and 2D-STE parameters to the clinical data, RV fractional area change (Model-2, r2=0.417, P<0.001), RV global longitudinal strain (Model-3, r2=0.454, P=0.001), RV intraventricular dyssynchrony (Model-4: r2=0.474, P<0.001) and interventricular dyssynchrony (Model-5, r2=0.483, P<0.001) were identified as independent predictors of PVO2. Interventricular dyssynchrony, calculated as the SD of the time intervals of nine segments, was independently associated with risk assessment (odd ratio 1.027, 95% CI: 1.003–1.052, P=0.03). The area under the receiver-operating characteristic curve (AUC) was 0.73 (P<0.001).ConclusionsInterventricular dyssynchrony detected by 2D-STE contributed to a better evaluation of exercise capacity and disease severity in PcPH patients.

Measurement of the Intra-ventricular Mechanical Dyssynchrony in Cardiac Magnetic Resonance Images

Measurement of the mechanical dyssynchrony of the ventricle is important for the cardiac resynchronization therapy (CRT) and the evaluation of patients with heart failures. So far, feature-tracking cardiovascular magnetic resonance (FT-CMR) has become the most popular method for measuring the mechanical dyssynchrony. FT-CMR calculates the strain values based on the pre-defined segments of the ventricle and thus it might miss some important regional information. In this paper, we propose a new approach to measure the intra-ventricular mechanical dyssynchrony based on the uniformly sampled points from all the regions of the ventricle. Accordingly, the proposed approach will not miss any regional information of the ventricle. In addition, the proposed approach is fully automatic and not depedent on the training sets. It calculates the mechnical dyssynchrony rapidly and determines whether the tested case is normal or patient immdiately. The proposed approach was validated with 40 tested cases (20 normal cases and 20 patient cases). Experimental results showed that the fully automatic intra-ventricular mechanical dyssynchrony measurement approach achieved 100% diagnosis accuracy for the left ventricle (LV) and achieved 95% diagnoisis accuracy for the right ventricle (RV).

Endothelial dysfunction and glycocalyx shedding in heart failure: insights from patients receiving cardiac resynchronisation therapy.

To determine (a) whether chronic heart failure with reduced ejection fraction (HFrEF) is associated with increased glycocalyx shedding; (b) whether glycocalyx shedding in HFrEF with left ventricular dyssynchrony is related to inflammation, endothelial dysfunction and/or redox stress and is ameliorated by cardiac resynchronisation therapy. Glycocalyx shedding has been reported to be increased in heart failure and is a marker of increased mortality. Its role in dyssynchronous systolic heart failure and the effects of cardiac resynchronisation therapy (CRT) are largely unknown. Twenty-six patients with dyssynchronous HFrEF were evaluated before and 6months after CRT insertion. Echocardiographic septal to posterior wall delay (SPWD) assessed intra-ventricular mechanical dyssynchrony, and quality of life, integrity of nitric oxide (NO) signalling, inflammatory and redox-related biomarkers were measured. Glycocalyx shedding was quantitated via plasma levels of the glycocalyx component, syndecan-1. Syndecan-1 levels pre-CRT were inversely correlated with LVEF (r = - 0.45, p = 0.02) and directly with SPWD (r = 0.44, p = 0.02), QOL (r = 0.39, p = 0.04), plasma NT-proBNP (r = 0.43, p = 0.02), and the inflammatory marker, symmetric dimethylarginine (SDMA) (r = 0.54, p = 0.003). On multivariate analysis, syndecan-1 levels were predicted by SPWD and SDMA (β = 0.42, p = 0.009 and β = 0.54, p = 0.001, respectively). No significant correlation was found between syndecan-1 levels and other markers of endothelial dysfunction/inflammatory activation. Following CRT there was no significant change in syndecan-1 levels. In patients with dyssynchronous HFrEF, markers of glycocalyx shedding are associated withthe magnitude of mechanical dyssynchrony and elevation of SDMA levels and inversely with LVEF. However, CRT does not reverse this process.

Comparison of three-dimensional echocardiography and speckle tracking echocardiography in quantification and mapping of intraventricular mechanical dyssynchrony

ObjectivesThe aim of the study is to compare two advanced methods of evaluation of left ventricular mechanical dyssynchrony (LVMD), the speckle tracking echocardiography (STE) and the three-dimensional echocardiography (3DE). MethodsOne hundred thirty-six subjects, with or without LV dysfunction and with or without bundle branch block (BBB), were included in this study, designed to investigate agreement between magnitude and spatial pattern of LVMD as assessed by 3DE and STE. The frequency and severity of LVMD and localization of most asynchronous segments were compared. ResultsBoth 3DE and STE revealed progressive rise in frequency and magnitude of LVMD with increasing disease severity. Dyssynchrony was dependent on left ventricle ejection fraction rather than the QRS duration. The frequency and magnitude of dyssynchrony were maximum in patients having LV dysfunction with left BBB. Compared with STE, 3DE diagnosed LVMD more frequently in patients having LV dysfunction with narrow QRS (17.6% vs 60.3%, respectively; P < 0.001). When the two methods were compared for localization of most asynchronous segments, the results matched only in about 50% cases. ConclusionsBoth 3DE and STE provided consistent results with progressive rise in magnitude of LVMD, correlating with disease severity. 3DE diagnosed more patients as having LVMD in those having LV dysfunction with narrow QRS. The most delayed segment assessed by two methods matched only in about half the cases. Correlation with clinical CRT responsiveness is needed to conclude which method is more accurate in dyssynchrony mapping for targeted lead placement.

Correlation of QRS duration with intraventricular mechanical dyssynchrony on tissue Doppler imaging in heart failure

Introductions: Wide QRS complex with left bundle branch block morphology is one of the three criteria for cardiac resynchronization therapy (CRT) in heart failure (HF) patients who do not improve on medical management. Approximately 30% of patients do not respond to CRT. This study investigates to find out to what extent the wide QRS duration correlates with the intraventricular mechanical dyssynchrony (IVMD) as measured by Tissue Doppler Imaging (TDI) echocardiography.&#x0D; Methods: The HF patients of dilated or ischemic cardiomyopathy with ejection fraction £35% admitted in the medical ward of Patan Hospital, Nepal from March to August 2017 were enrolled in the study. They were divided into two groups, narrow QRS duration of &lt;120ms (Gr1) and wide QRS duration of ³120ms (Gr2). TDI was performed to measure time to peak systolic velocity of the left ventricular walls. The IVMD, defined as 60 ms (millisecond) or greater difference in time to peak velocity between any two points of the left ventricular walls, was compared in both groups.&#x0D; Results: There were 26 patients, 18 in group-1, and eight in Gr2.In Gr1, IVMD was observed 13/18 (72%) patients and in group-2 in 7/8 (87%) patients, (χ2 = 0.70, p = 0.403). There was no significant difference of IVMD between Gr1 and Gr2 (73±36ms vs 97±38ms, t = 1.54, p = 0.136). &#x0D; Conclusions: Assessment of intraventricular mechanical dyssynchrony (IVMD) by Tissue Doppler Imaging (TDI) is probably superior to QRS duration in heart failure patients.

Incidence of Ventricular Arrhythmias in Association with Left Ventricular Dyssynchrony in Chronic Ischemic Patients

AbstractBackground: Intra ventricular mechanical dyssynchrony may play an important role in ventricular arrhythmogenesis in chronic ischemic patients.Aim of the Study: To detect the prevalence of ventricular arrhythmia in chronic ischemic patients in association with left ventricular dyssynchrony assessed by left ventricular longitudinal strain.Methods: The study included 50 patients with ischemic heart disease confirmed by coronary angiography. Speckle tracking echocardiography was performed. Patients were divided into 2 groups according to presence or absence of left ventricular mechanical dyssynchrony, considering difference in time to peak ³130ms by longitudinal strain between any two opposing segment at basal and mid level in LV 12 segments positive for mechanical dyssynchrony. Every patient in both groups underwent 24 hours holter monitoring for detection of ventricular arrhythmia.Results: The study results showed that there were 45 males and 5 females. Mean age ±SD was 51.00±7.06 years. Mean heart rate was 76.92±13.29 beat/minute. Patients were divided into 2 groups. Group I included 40 patients with left ventricular dyssynchrony and mean time to peak SD was 102.5±34.16m sec and Group II included 10 patients without left ventricular dyssynchrony and mean time to peak SD was 82.3±45.1msec. 24 hours ECG Holter monitoring data showed that there was higher incidence of ventricular runs in Group I with positive dyssynchrony patients (47.5%) than those in Group II with negative dyssynchrony patients (20%).Conclusion: Left ventricular dyssynchrony assessed by left ventricular longitudinal strain could be a predictor for increased risk of ventricular arrhythmia.

Robust and automatic diagnosis of the intraventricular mechanical dyssynchrony for the left ventricle in cardiac magnetic resonance images.

Robust and automatic diagnosis of the mechanical dyssynchrony for the left ventricle is essential for the cardiac resynchronization therapy. However, no existing method could meet the desired accuracy yet. In this paper, a new approach is proposed for auto-diagnosis of the intraventricular mechanical dyssynchrony of the left ventricle based on a series of image processing and signal processing techniques. Firstly, the boundary of the left ventricle is identified automatically by the segmentation method. Secondly, the correspondence trajectories are computed based on the tangent field to make sure that they are perpendicular to all the intercepted boundaries. Thirdly, the intercepted points are smoothed by the proposed Fourier shape filter to eliminate noise and increase the diagnosis accuracy. Fourthly, the mechanical dyssynchrony is defined as the lag times between the periodic change of the sampled boundary points and the periodic change of the area of the left ventricle. It is calculated by cross-correlation. The segmentation method is trained with 10 cases, the proposed approach is evaluated with other 40 tested cases (20 normal cases and 20 patient cases), and the diagnosis accuracy is 100%. Experimental results showed that the proposed approach can accurately diagnose whether the left ventricle has mechanical dyssynchrony or not from the computed lag times. The proposed approach is robust in auto-diagnosis of the mechanical dyssynchrony for the left ventricle in cardiac magnetic resonance images.

Electrocardiographic correlates of mechanical dyssynchrony in recipients of cardiac resynchronization therapy devices

The relationship between electrical and mechanical indices of cardiac dyssynchronization in systolic heart failure (HF) remains poorly understood. We examined retrospectively this relationship by using the daily practice tools in cardiology in recipients of cardiac resynchronization therapy (CRT) systems. We studied 119 consecutive patients in sinus rhythm and QRS ≥ 120 ms (mean: 160 ± 17 ms) undergoing CRT device implantation. P wave duration, PR, ePR (end of P wave to QRS onset), QT, RR-QT, JT and QRS axis and morphology were putative predictors of atrioventricular (diastolic filling time [DFT]/RR), interventricular mechanical dyssynchrony (IVMD) and left intraventricular mechanical dyssynchrony (left ventricular pre-ejection interval [PEI] and other measures) assessed by transthoracic echocardiography (TTE). Correlations between TTE and electrocardiographic measurements were examined by linear regression. Statistically significant but relatively weak correlations were found between heart rate (r=-0.5), JT (r=0.3), QT (r=0.3), RR-QT intervals (r=0.5) and DFT/RR, though not with PR and QRS intervals. Weak correlations were found between: (a) QRS (r=0.3) and QT interval (r=0.3) and (b) IVMD > 40 ms; and between (a) ePR (r=-0.2), QRS (r=0.4), QT interval (r=0.3) and (b) LVPEI, though not with other indices of intraventricular dyssynchrony. The correlations between electrical and the evaluated mechanical indices of cardiac dyssynchrony were generally weak in heart failure candidates for CRT. These data may help to explain the discordance between electrocardiographic and echocardiographic criteria of ventricular dyssynchrony in predicting the effect of CRT.

Impact of elective PCI on left intraventricular mechanical dyssynchrony in patients with chronic stable angina (tissue Doppler study)

Abstract Aim To detect the impact of elective PCI on left intraventricular mechanical dyssynchrony in patients with chronic stable angina. Methods 100 patients with chronic stable angina were included and divided into two groups according to LV systolic and diastolic mechanical dyssynchrony measured by TSI 12-segments SD and Te-SD. 24 h then 1 month after PCI, patients with dyssynchrony were reclassified into improved vs persistent LV mechanical dyssynchrony. Results At baseline 72% had LV systolic mechanical dyssynchrony. Patients with LV systolic mechanical dyssynchrony were significantly older (58.42 ± 4.617 vs. 54.64 ± 3.456, respectively, p p value p value p p value p value Conclusion PCI had significant effect on LV systolic and diastolic mechanical intraventricular dyssynchrony.

Influence of percutaneous atrial septal defect closure on inter- and intra-ventricular mechanical dyssynchrony in adults: evaluation of strain pattern

Previous studies using speckle-tracking echocardiography (STE) for quantifying the functions of the right and left ventricles (RV and LV, respectively) in the presence of percutaneous atrial septal defect (ASD) closure have focused on the peak systolic strain (PSS). This study investigated changes in the mechanical dyssynchrony of ventricular contraction before and after ASD closure, issues that have been little addressed in the literature. Thirty-one adults with ASD were studied using two-dimensional STE before and 24h after ASD closure. Thirty-one healthy age- and sex-matched subjects were recruited as controls. Global and segmental PSS values from the longitudinal, circumferential, and radial directions were analyzed. The time to peak systolic strain (PSST) and the standard deviation of the time to peak strain (SDT) among segments in each direction were calculated, to investigate the inter- and intra-ventricular mechanical dyssynchrony in these patients and improvements after closure. Compared to the control group, patients with ASD had higher RV free-wall longitudinal systolic strain, with increased PSST and SDT. The SDT values of the LV longitudinal and circumferential strains were also increased. By 24h after ASD closure, the RV free-wall longitudinal strain and its PSST and SDT had reverted to normal levels. The LV circumferential strain was increased, and its SDT was decreased. The contraction period of the RV and myocardial contraction dyssynchrony in the RV and LV were increased in ASD patients. The inter- and intra-ventricular mechanical utilities were improved after percutaneous closure of the ASD.

Systolic Function and Intraventricular Mechanical Dyssynchrony Assessed by Advanced Speckle Tracking Imaging with N-terminal Prohormone of Brain Natriuretic Peptide for Outcome Prediction in Chronic Heart Failure Patients

The aim of this study was to assess longitudinal systolic function and mechanical synchrony parameters derived from advanced speckle tracking echocardiography (STE) and to determine their correlation with N-terminal prohormone of brain natriuretic peptide (NT-proBNP). Their influence on heart failure (HF) outcomes at a one-year follow-up, not clarified in previous studies, was also examined. Advanced STE was performed from August 2009 to January 2012 in 103 chronic HF patients at the University Kebangsaan Malaysia Medical Center to assess their longitudinal systolic function and synchrony parameters; NT-proBNP blood measurement was taken at the same time. Longitudinal cardiac velocity; strain; strain rate; displacement; intraventricular mechanical dyssynchrony based on the standard deviation (SD) of time to peak systolic strain rate (Tsr-SD); displacement, and antero-septal to posterior (AS-P) delay were associated with cardiac events. In multivariate analysis, NT-proBNP and AS-P delay were identified as independent predictors for cardiac events. Significant correlations were found between NT-proBNP and longitudinal velocity; displacement; strain; strain rate, and ejection fraction. Log NT-proBNP levels correlated moderately with the SD of time to peak displacement and to peak strain, and there was a small correlation with maximal differences and SD of time to peak velocity. A multiple linear analysis revealed that NT-proBNP levels significantly correlated to age, ejection fraction and velocity. Advanced STE is a promising technique which accelerates the clinical application of the quantification of myocardial function and synchrony. STE parameters and NT-proBNP have the ability to identify patients at higher risk of death and hospitalisation.

Analysis of longitudinal strain integrals during rest and effort on heart failure patients

Purpose: Left ventricular mechanical dyssynchrony is based classically on the analysis of velocity or strain peak instants, which are detected manually. This method may not reflect the complexity of both contractility and timing of a dilated heart, particularly at exercise. We hypothesized that integral-based indicators of regional longitudinal strain signals, and their variation between rest and exercise, would provide additional information for the characterization of the evolution of heart failure patients. Methods: Forty-nine patients with NYHA II to III, ischemic (28%) or idiopathic DCM (72%), ejection fraction 29,6±7,1%, QRS width 138±35ms, were studied. All patients underwent submaximal supine bicycle exercise stress echocardiography. Thirty of 49 patients had a CRT device implantation following baseline evaluation. Patients were classified as responders (n=18) if they showed a decrease in LV end-systolic volume ≥15% at 6-months follow-up, non-responders (n=12) if not. Apical-4 chamber longitudinal strain was recorded manually on a dedicated software (EchoPAC PC, GE Healthcare) and then strain data was exported for a detailed analysis, based on custom-made methods and algorithms. Integrals of strain signals were calculated for each segment, from the beginning of the cardiac cycle (QRS onset), to the instant of the peak of longitudinal strain. Results: Concerning the global population (n=49), no significant change between rest and exercise was observed for septal and lateral peak of longitudinal strain, or intraventricular mechanical dyssynchrony, when recorded manually on the Echopac interface. Integrals to minimum of longitudinal strain decreased significantly between rest and exercise for mid septal segments (1,96±1,30 vs. 1,54±0,91, p<0,01), but no variation was observed for mid-lateral segments (1,96±1,22 vs. 2,04±1,02, p=NS). CRT responders showed an increase in integral to minimum for the mid-lateral segment (1,64±0,90 at rest vs. 2,26±1,20 at exercise; p<0,01) whereas CRT non-responders did not. The latter showed a decrease in integral to minimum for mid-septal segment during exercise (2,21±1,36 vs. 1,30±0,89; p<0,01) that was not observed on CRT responders. Conclusion: Integral-derived longitudinal strain curves give new insights into LV mechanics for heart failure patients during exercise, revealing different patterns between the septum and the lateral wall. These patterns may be useful to identify potential CRT responders.

Analysis of longitudinal strain integrals during rest and effort on heart failure patients

Purpose: Left ventricular mechanical dyssynchrony is based classically on the analysis of velocity or strain peak instants, which are detected manually. This method may not reflect the complexity of both contractility and timing of a dilated heart, particularly at exercise. We hypothesized that integral-based indicators of regional longitudinal strain signals, and their variation between rest and exercise, would provide additional information for the characterization of the evolution of heart failure patients. Methods: Forty-nine patients with NYHA II to III, ischemic (28%) or idiopathic DCM (72%), ejection fraction 29,6±7,1%, QRS width 138±35ms, were studied. All patients underwent submaximal supine bicycle exercise stress echocardiography. Thirty of 49 patients had a CRT device implantation following baseline evaluation. Patients were classified as responders (n=18) if they showed a decrease in LV end-systolic volume ≥15% at 6-months follow-up, non-responders (n=12) if not. Apical-4 chamber longitudinal strain was recorded manually on a dedicated software (EchoPAC PC, GE Healthcare) and then strain data was exported for a detailed analysis, based on custom-made methods and algorithms. Integrals of strain signals were calculated for each segment, from the beginning of the cardiac cycle (QRS onset), to the instant of the peak of longitudinal strain. Results: Concerning the global population (n=49), no significant change between rest and exercise was observed for septal and lateral peak of longitudinal strain, or intraventricular mechanical dyssynchrony, when recorded manually on the Echopac interface. Integrals to minimum of longitudinal strain decreased significantly between rest and exercise for mid septal segments (1,96±1,30 vs. 1,54±0,91, p<0,01), but no variation was observed for mid-lateral segments (1,96±1,22 vs. 2,04±1,02, p=NS). CRT responders showed an increase in integral to minimum for the mid-lateral segment (1,64±0,90 at rest vs. 2,26±1,20 at exercise; p<0,01) whereas CRT non-responders did not. The latter showed a decrease in integral to minimum for mid-septal segment during exercise (2,21±1,36 vs. 1,30±0,89; p<0,01) that was not observed on CRT responders. Conclusion: Integral-derived longitudinal strain curves give new insights into LV mechanics for heart failure patients during exercise, revealing different patterns between the septum and the lateral wall. These patterns may be useful to identify potential CRT responders.

Mechanical Dyssynchrony is Similar in Different Patterns of Left Bundle-Branch Block

BackgroundLeft bundle-branch block (LBBB) and the presence of systolic dysfunction are the major indications for cardiac resynchronization therapy (CRT). Mechanical ventricular dyssynchrony on echocardiography can help identify patients responsive to CRT. Left bundle-branch block can have different morphologic patterns. ObjectiveTo compare the prevalence of mechanical dyssynchrony in different patterns of LBBB in patients with left systolic dysfunction. MethodsThis study assessed 48 patients with ejection fraction (EF) < 40% and LBBB consecutively referred for dyssynchrony analysis. Conventional echocardiography and mechanical dyssynchrony analysis were performed, interventricular and intraventricular, with ten known methods, using M mode, Doppler and tissue Doppler imaging, isolated or combined. The LBBB morphology was categorized according to left electrical axis deviation in the frontal plane and QRS duration > 150 ms. ResultsThe patients' mean age was 60 ± 11 years, 24 were males, and mean EF was 29% ± 7%. Thirty-two had QRS > 150 ms, and 22, an electrical axis between −30° and +90°. Interventricular dyssynchrony was identified in 73% of the patients, while intraventricular dyssynchrony, in 37%-98%. Patients with QRS > 150 ms had larger left atrium and ventricle, and lower EF (p < 0.05). Left electrical axis deviation associated with worse diastolic function and greater atrial diameter. Interventricular and intraventricular mechanical dyssynchrony (ten methods) was similar in the different LBBB patterns (p = ns). ConclusionIn the two different electrocardiographic patterns of LBBB analyzed, no difference regarding the presence of mechanical dyssynchrony was observed.

Single beat determination of intraventricular systolic dyssynchrony in patients with atrial fibrillation and systolic dysfunction.

Background:Atrial fibrillation (AF) is the most common clinically significant cardiac arrhythmia. However, diagnosis of intraventricular dyssynchrony in patients with AF is difficult due to beat-to-beat variation. Additionally, evaluation of mechanical dyssynchrony in the traditional method is based on average of 5 to 10 beats, which is exhausting and time consuming. Single-beat evaluation of a beat with equal subsequent cardiac cycles has been proposed as an accurate method in patients with AF.Objectives:We proposed to evaluate intraventricular mechanical dyssynchrony by measuring time-to-peak systolic velocity between basolateral and basoseptal segments (septum to lateral wall delay) using Tissue Doppler Study (TDI) by two different methods.Materials and Methods:31 patient (68 ± 10.3 years) with heart failure (EF < 35%) and AF rhythm, R-R cycle length more than 500 msec were evaluated. We found a target beat in which preceding R-R (R-R1) to pre-preceding R-R (R-R2) ratio was 1(RR1/RR2 = 1) then measured the intraventricular dyssynchrony in that cycle. Intraventricular dyssynchrony was also determined and averaged for 8 consecutive cardiac cycles. The values at RR1/RR2 = 1 were compared with the average of intraventricular dyssynchrony in eight cycles and the relationship between dyssynchrony were evaluated by paired T-test, linear Pearson correlation (r2), linear regression analysis.Results:The average of dyssynchrony in eight cycles showed a positive correlation with dyssynchrony in target beat RR1/RR2 = 1. Average of dyssynchrony in target beat was 46.77 msec, and average of 8 cycle was = 47.701, (P value = 0.776, Pearson linear correlation 0.769).Conclusions:Measurement of intraventricular dyssynchromy in basoseptal and basolateral segments in AF and heart failure patients in a single beat with RR1/RR2 = 1 , were very similar to the average value of eight cardiac cycle.

Application of echocardiography in resynchronization treatment of heart failure patients.

To review the updated research progress about the application of echocardiography in resynchronization treatment of chronic heart failure patients. The data used in this review were from PubMed, published in English and using the key terms "heart failure", "echocardiography" and "cardiac resynchronization therapy". Relevant articles were reviewed and selected to address the stated purpose. Increasing numbers of studies have suggested the importance of echocardiography in resynchronization treatment of chronic heart failure patients. Echocardiography can evaluate atrioventricular, inter- and intra-ventricular mechanical dyssynchrony before cardiac resynchronization therapy (CRT), as a guidance to assess the optimal left ventricular (LV) pacing location, optimize the atrioventricular and interventricular delays and predict response to CRT. Echocardiography is both non invasive and easily repeatable, and plays a crucial role in appraisal of heart synchronism, instruction of actuator placement, optimization of the device procedure, and prediction of the response to CRT.