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Background: The new three-dimensional speckle tracking echocardiography (3DSTE) may enable comprehensive quantification of global left ventricular (LV) myocardial mechanics., Methods: Twenty-four patients aged 29.3 ± 5.2 years and 22 controls were studied. 3DSTE was performed to assess LV 3D global strain, twist and torsion, ejection fraction, and systolic dyssynchrony index (SDI). The LV SDI was calculated as % of SD of times-to-peak strain of 16 segments/RR interval. The global performance index (GPI) was calculated as (global 3D strain·torsion)/SDI. Area under the receiver operating characteristic curve (AUC) was calculated to determine the capability of 3DSTE parameters to discriminate between patients with (cardiac magnetic resonance T2* <20 ms) and those without myocardial iron overload., Results: Compared with controls, patients had significantly lower LV global 3D strain (P < 0.001), twist (P = 0.01), torsion (P = 0.04), and ejection fraction (P < 0.001) and greater SDI (P < 0.001). The GPI was lower in patients than controls (P < 0.001). T2* value correlated positively with global 3D strain (r = 0.74, P < 0.001) and GPI (r = 0.63, P = 0.001), and negatively with SDI (r = -0.44, P = 0.03). The AUCs of GPI, global 3D strain, ejection fraction, torsion, and 1/SDI were 0.94, 0.90, 0.87, 0.82, and 0.70, respectively. The GPI cutoff of 2.7°/cm had a sensitivity of 94.9% and a specificity of 88.9% of differentiating patients with from those without myocardial iron overload., Conclusions: The LV composite index of strain, torsion, and dyssynchrony derived from 3DSTE enables sensitive detection of myocardial iron overload in patients with thalassemia., (© 2016, Wiley Periodicals, Inc.)

Background: Ventricular diastolic dysfunction in patients with repaired tetralogy of Fallot (TOF) may affect atrial mechanics. This study aimed to explore right atrial (RA) and left atrial (LA) mechanics in repaired TOF patients and their relationship with ventricular diastolic function., Methods: Fifty-four patients (36 males), aged 17.8 ± 8.3 years, who had undergone TOF repair at 3.9 ± 3.3 years and 40 healthy subjects aged 16.9 ± 6.3 years (P = 0.57) were studied. Right and LA peak positive, peak negative, and total strain, strain rate at ventricular systole (SRs ), early diastole (SRed ), and atrial contraction (SRac ), and electromechanical delay were determined using speckle tracking echocardiography (STE). Ventricular diastolic function was assessed by tissue Doppler imaging and STE. Ventricular volumes and pulmonary regurgitant volume were derived from 3D echocardiography., Results: Compared with controls, patients had significantly lower RA and LA peak positive and total strain, SRs , SRed , and SRac (all P < 0.001). The timing of RA (178 ± 33 msec vs. 152 ± 17 msec, P < 0.001) and LA (170 ± 32 msec vs. 152 ± 24 msec, P = 0.006) electromechanical coupling (EMC) was significantly longer in patients than in controls. The RA total strain, SRs , SRed , SRac , and EMC correlated positively with corresponding LA parameters (all P < 0.001). The RA and LA total strain and SRed were associated positively with diastolic annular velocities and strain rates of respective ventricles (all P < 0.05). The LA SRed correlated negatively with pulmonary regurgitant volume (r = -0.33, P = 0.016) and RV end-diastolic volume (r = -0.33, P = 0.015)., Conclusion: Mechanics of both atria are impaired in patients after repair of TOF and are associated with diastolic performance of the respective ventricles., (© 2014, Wiley Periodicals, Inc.)

Background: Myocardial fibrosis and perfusion abnormalities can occur in patients with Kawasaki disease (KD). We explored using the new three-dimensional speckle tracking echocardiography (3DSTE) the left ventricular (LV) mechanics in adolescents and young adults with a history of KD., Methods: Twenty-five KD patients (18 males) aged 17.0 ± 5.2 years, 14 with (group I) and 11 without (group II) coronary aneurysms, were studied. The 3D volume datasets were acquired for quantification of LV global 3D strain, global and regional area strain, systolic dyssynchrony index (SDI), twist, twist gradient (twist/LV length), and ejection fraction., Results: The results were compared with those of 14 age-matched controls. Of the 14 group I patients, 6 had left, 2 had right, and 6 had both left and right coronary aneurysms. Compared with controls, group I patients had significantly lower LV systolic global 3D strain (43.7 ± 7.3% vs. 50.4 ± 6.6%, P = 0.02), twist (8.7 ± 1.3° vs. 11.4 ± 2.0°, P < 0.001), and twist gradient (1.5 ± 0.3°/cm vs. 1.9 ± 0.4°/cm, P = 0.01), greater SDI (6.8 ± 1.9% vs. 4.7 ± 1.9%, P < 0.001), and similar ejection fractions. Six patients in group I had perfusion defects, who had global 3DSTE parameters similar to those of the 8 patients without perfusion abnormalities (all P > 0.05). For group II patients, only the global area strain was significantly lower than that of controls (37.6 ± 3.5% vs. 40.7 ± 3.6%, P = 0.038)., Conclusion: In adolescents and young adults with a history of KD, impairment of LV mechanics occurs and is worse in patients with than those without coronary complications., (© 2013, Wiley Periodicals, Inc.)

Background: Altered septal curvature and left ventricular (LV) geometry secondary to right ventricular (RV) dilation render two-dimensional assessment of LV mechanics difficult in repaired tetralogy of Fallot (TOF) patients. The novel three-dimensional (3D) speckle tracking echocardiography enables comprehensive evaluation of true 3D LV mechanics., Methods and Results: Seventy-six patients aged 23.6 ± 8.3 years, 55 with isolated repair (group I) and 21 with subsequent pulmonary valve replacement (group II), and 34 healthy controls were studied. Three-dimensional volume datasets were acquired for assessment of LV global and regional 3D strain, systolic dyssynchrony index (SDI), twist, twist gradient (twist/LV length), and ejection fraction. A global performance index was calculated as (global 3D strain•twist gradient)/SDI. The septal curvature and LV eccentricity were determined from the mid-ventricular short-axis. Compared with controls, group I and II patients had significantly reduced LV global 3D strain, LV twist, twist gradient, septal curvature, and global performance index, and greater LV systolic and diastolic eccentricity and SDI (all p<0.05). All but the four apical LV segments in patients had reduced regional 3D strain compared with controls (all p<0.05). Septal curvature correlated with LV global 3D strain (r=0.41, p<0.001), average septal strain (r=0.38, p<0.001), twist (r=0.32, p<0.001), twist gradient (r=0.33, p<0.001), and global performance index (r=0.43, p<0.001)., Conclusions: Adverse 3D LV mechanics as characterized by impaired global and regional 3D systolic strain, mechanical dyssynchrony, and reduced twist is related to reduced septal curvature in repaired TOF patients with and without pulmonary valve replacement.

Background: The aim of this case-control study was to assess the usefulness of three-dimensional (3D) speckle-tracking echocardiography in the evaluation of global left ventricular (LV) myocardial performance in adolescent and adult survivors of childhood cancers., Methods: Fifty-three anthracycline-treated survivors of childhood cancers (mean age, 18.6 ± 5.1 years) and 38 controls were studied. Three-dimensional speckle-tracking echocardiography was performed to assess LV 3D global and segmental strain, time to peak segmental 3D strain, LV torsion, and ejection fraction. LV systolic dyssynchrony index (SDI) was calculated as the percentage of the standard deviation of times to peak strain of the 16 segments divided by the RR interval. A global performance index (GPI) was calculated as (global 3D strain × torsion)/SDI. The area under the receiver operating characteristic curve was calculated to determine the capability of various echocardiographic indices to discriminate between patients and controls., Results: Compared with controls, patients had significantly reduced LV global 3D strain (P < .001), torsion (P < .001), and GPI (P < .001) and greater SDI (P < .001). All except the basal anteroseptal segment in patients had reduced regional 3D strain compared with controls (P < .05 for all). Global 3D strain (P = .018), SDI (P = .003), and GPI (P = .02) were correlated with cumulative anthracycline dose. The areas under the curves for GPI, global 3D strain, 1/SDI, torsion, and ejection fraction were 0.92, 0.79, 0.79, 0.79, and 0.78, respectively. A GPI cutoff of 10.6°/cm had sensitivity of 84.9% and specificity of 81.6% of differentiating patients from controls., Conclusions: Three-dimensional speckle-tracking echocardiography enables the derivation of an index of LV global performance that incorporates LV 3D strain, dyssynchrony, and torsion for the sensitive detection of altered LV mechanics in childhood cancer survivors., (Copyright © 2013 American Society of Echocardiography. Published by Mosby, Inc. All rights reserved.)

Aims: Subendocardial layer of the ventricle has been shown to be sensitive to anthracycline damage. This study tested the hypothesis that anthracycline therapy for childhood malignancies has differential impact on deformation and rotation of left ventricular (LV) subendocardial and subepicardial layers and hence transmural myocardial strain and rotation gradients., Methods and Results: Thirty-two anthracycline-treated survivors of childhood malignancies aged 19.3 ± 5.4 years and 28 controls were studied. Apical four-chamber and parasternal LV short-axis acquisitions at base, papillary muscle level, and apex were analysed for layer-specific myocardial strain and apical and basal rotation and rotational velocities using two-dimensional speckle tracking echocardiography. Transmural strain and rotation gradients were calculated as differences between peak systolic strain and rotation between the inner and outer layers, respectively. Compared with controls, patients had significantly lower transmural circumferential, but not radial or longitudinal, strain gradients (P< 0.05), accounted by the reduced subendocardial circumferential strain, at all three ventricular levels (all P< 0.05). No significant difference in basal transmural rotation gradient was found between patients and controls (P= 0.32). On the other hand, apical rotation, systolic twisting velocity, and diastolic untwisting velocity were reduced preferentially at the subendocardial layer in patients (all P< 0.05), hence accounting for their significantly reduced transmural rotation gradient compared with controls (P< 0.001). The LV ejection fraction correlated inversely with apical transmural circumferential strain gradient (r= -0.39, P= 0.002) and rotation gradient (r= 0.33, P= 0.01)., Conclusion: Preferential impairment of subendocardial circumferential deformation and apical rotation with consequential reduction of transmural circumferential strain and rotation gradients occurs in anthracycline-treated survivors of childhood cancers.

Background: The effects of right ventricular (RV) pacing on left ventricular (LV) diastolic function are unknown. This study aimed to test the hypothesis that right ventricular (RV) pacing is associated with LV diastolic dysfunction and impairment of LV torsion in children and young adults with congenital heart block., Methods: Eighteen patients aged 20 ± 7 years and 12 healthy controls aged 19 ± 7 years were studied. Transmitral and mitral annular diastolic velocities and global longitudinal diastolic strain rate were determined and compared between the 2 groups. Parameters of LV torsion including peak systolic basal and apical rotations, and systolic twisting and diastolic untwisting velocities were further determined by speckle tracking echocardiography. In 12 patients, these parameters were compared before and after interruption of RV pacing., Results: Compared with controls, patients had significantly lower mitral early diastolic annular velocity (p=0.007), LV global diastolic strain rate (p<0.001), basal (p<0.001) and apical (p=0.002) rotations, peak systolic torsion (p<0.001), and peak systolic twisting velocities (p=0.009). In patients, the peak diastolic untwisting velocity correlated with peak systolic torsion (r=0.64, p=0.004) and peak systolic twisting velocity (r=0.74, p<0.001). No significant improvement in LV diastolic function or torsion was observed during pacing interruption (all p>0.05)., Conclusion: Right ventricular pacing in childhood is associated with LV diastolic dysfunction and impaired LV torsion, which do not improve with pacing interruption., (Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.)

Background: The aim of this study was to test the hypothesis that dyssynchronous contraction of functional single ventricles occurs in Fontan patients and is related to indices of myocardial deformation and global ventricular function., Methods: Twenty patients with tricuspid atresia (mean age, 23.5 ± 7.1 years) were studied 17.8 ± 3.8 years after undergoing the Fontan procedure. Three-dimensional echocardiographic data were acquired for determination of left ventricular (LV) volumes and systolic dyssynchrony indices. LV myocardial deformation was determined using speckle-tracking echocardiography. Calibrated integrated backscatter intensity was measured as an index of myocardial fibrosis. The results were compared with those in 20 controls., Results: Compared with controls, patients had significantly greater systolic dyssynchrony indices (6.13 ± 1.32% vs 4.06 ± 0.84%, P < .001). The prevalence of LV mechanical dyssynchrony (systolic dyssynchrony index > 5.74%) in patients was 55% (95% confidence interval, 32%-77%). LV global systolic longitudinal, radial, and circumferential strain (P < .001 for all), longitudinal systolic (P < .001) and early diastolic (P < .001) strain rate, and circumferential systolic (P < .001) and early diastolic (P = .009) strain rate were significantly lower in patients than in controls, while the average calibrated integrated backscatter was higher (P < .001). Patients with LV dyssynchrony (n = 11) had lower global LV longitudinal strain (P = .02), reduced LV ejection fractions (P = .002), and higher average calibrated integrated backscatter (P = .03) compared with those without LV dyssynchrony (n = 9)., Conclusions: A high proportion of patients with tricuspid atresia after the Fontan operation exhibit LV mechanical dyssynchrony, which may in part be related to myocardial fibrosis and has implications for myocardial deformation and global ventricular function., (Copyright © 2012 American Society of Echocardiography. Published by Mosby, Inc. All rights reserved.)

Background: Performance of the left ventricle during exercise stress in thalassaemia patients is uncertain. We aimed to explore the phenomenon of dynamic dyssynchrony and assess contractile reserve in patients with beta-thalassaemia major and determine their relationships with myocardial iron load., Methods and Results: Thirty-two thalassaemia patients (16 males), aged 26.8 ± 6.9 years, without heart failure and 17 healthy controls were studied. Their left ventricular (LV) volumes, ejection fraction, systolic dyssynchrony index (SDI), and myocardial acceleration during isovolumic LV contraction (IVA) were determined at rest and during submaximal bicycle exercise testing using 3-dimensional and tissue Doppler echocardiography. Myocardial iron load as assessed by T2* cardiac magnetic resonance in patients were further related to indices of LV dyssynchrony and contractile reserve. At rest, patients had significantly greater LV SDI (p<0.001) but similar IVA (p = 0.22) compared with controls. With exercise stress, the prevalence of mechanical dyssynchrony (SDI>4.6%, control+2SD) increased from baseline 25% to 84% in patients. Δ SDI(exercise-baseline) correlated with exercise-baseline differences in LV ejection fraction (p<0.001) and stroke volume (p = 0.006). Compared with controls, patients had significantly less exercise-induced increase in LV ejection fraction, cardiac index, and IVA (interaction, all p<0.05) and had impaired contractile reserve as reflected by the gentler IVA-heart rate slope (p = 0.018). Cardiac T2* in patients correlated with baseline LV SDI (r = -0.44, p = 0.011) and IVA-heart rate slope (r = 0.36, p = 0.044)., Conclusions: Resting LV dyssynchrony is associated with myocardial iron load. Exercise stress further unveils LV dynamic dyssynchrony and impaired contractile reserve in patients with beta-thalassaemia major.

Background: Circulating carboxy-terminal propeptide of type I procollagen (PICP) and amino-terminal propeptide of type III procollagen (PIIINP) are biomarkers of collagen synthesis. We tested the hypothesis that circulating PICP and PIIINP are altered and may correlate with ventricular volume load and function in patients with repaired tetralogy of Fallot (TOF)., Methods and Results: Serum PICP and plasma PIIINP levels were determined in 39 patients with repaired TOF aged 17.7 ± 4.1 years and 25 healthy controls and correlated with right ventricular (RV) and left ventricular (LV) volumes, functional indices, and mechanical dyssynchrony as assessed by 3-dimensional and tissue Doppler echocardiography. Compared with controls, patients had significantly higher circulating PICP (P = .016) and PIIINP (P = .008) levels, worse RV function with intra-RV mechanical delay (all P < .001), impaired LV systolic functional indices (all P < .05), and greater LV systolic dyssynchrony index (SDI) (P < .001). For the whole cohort, circulating PICP and PIIINP levels correlated with age (P = .001 and P < .001, respectively), body mass index (P = .033 and P = .012, respectively), LV eccentricity (P = .035 and P = .046, respectively), RV end-diastolic volume (P = .029 and P = .047, respectively), and LV SDI (both P < .001). In addition, PICP levels correlated negatively with RV and LV isovolumic acceleration and RV ejection fraction. Multiple linear regression analysis identified LV SDI as a significant independent correlate of circulating levels of PICP (β = .31, P = .045) and PIIINP (β = .37, P = .004)., Conclusion: Circulating levels of PICP and PIIINP correlate positively with LV mechanical dyssynchrony in patients after TOF repair, implicating a possible role of increased collagen synthesis in its pathogenesis., (Copyright © 2011 Mosby, Inc. All rights reserved.)

Background: Anthracycline has been shown to degrade titin that plays a role in myocardial twisting and untwisting. This study aimed to test the hypothesis that left ventricular (LV) twisting and untwisting motion may be altered in children after anthracycline therapy., Methods: Thirty-six childhood leukemia survivors aged 15.6 ± 5.5 years and 20 healthy controls aged 16.8 ± 7.7 years (P = 0.54) were studied. LV twisting and untwisting motion was determined using speckle tracking imaging, whereas LV ejection fraction and systolic and diastolic mitral annular velocities were determined respectively by three-dimensional and tissue-Doppler echocardiography., Results: Compared with controls, patients had significantly lower LV ejection fraction (P = 0.01) but similar systolic and diastolic mitral annular velocities (all P > 0.05). Their peak LV torsion (P = 0.003), systolic twisting velocity (P < 0.001), and diastolic untwisting velocity (P = 0.04) were significantly lower than controls, which could be attributable to their reduced apical rotation (P = 0.03) and apical untwisting rate (P = 0.002). For the whole cohort, LV systolic torsion and twisting velocity correlated significantly with apical untwisting rate (P < 0.001) and LV diastolic untwisting velocity (P < 0.001). In patients, none of the twisting or untwisting parameters were found to correlate with cumulative anthracycline dose (all P > 0.05). Twenty-eight (78%) patients had LV ejection fractions ≥50%. Although their systolic and diastolic mitral annular velocities were similar to those of controls, their peak LV torsion (P = 0.005), apical untwisting rate (P = 0.01), and LV systolic twisting velocity (P = 0.001) remained significantly lower., Conclusion: Impairment of LV twisting and untwisting motion is evident in children after anthracycline therapy, even in those with "normal" LV ejection fractions., (© 2011, Wiley Periodicals, Inc.)

Objective: The M-mode-derived left ventricular shortening fraction is incorporated into most of the paediatric oncology protocols for monitoring of cardiotoxicity. This study tested the hypothesis that alteration of left ventricular myocardial deformation and mechanical dyssynchrony may occur in asymptomatic children after anthracycline therapy despite having left ventricular shortening fractions within the limits of normal., Design: Cross-sectional study., Setting: Tertiary paediatric cardiac centre., Methods: Left ventricular longitudinal, circumferential and radial myocardial deformation was determined using speckle tracking echocardiography in 45 patients aged 15.3+/-5.8 years. Real-time three-dimensional echocardiographic data were acquired for the measurement of left ventricular volumes and systolic dyssynchrony index (SDI), the latter derived from the dispersion of time-to-minimum regional volume using a 16-segment model. The results were compared with those of 44 controls., Results: Compared with controls, patients had reduced left ventricular global systolic longitudinal strain (p=0.012), circumferential strain (p<0.001), radial strain (p=0.006) and circumferential strain rate (SR; p=0.002). The cumulative anthracycline dose correlated negatively with global longitudinal (r=-0.33, p=0.027) and circumferential (r=-0.32, p=0.035) SR. The left ventricular SDI was significantly greater in patients than controls (4.46+/-1.52% vs 3.80+/-0.58%, p=0.03). The prevalence of left ventricular mechanical dyssynchrony (SDI >4.96%) in patients was 16% (95% CI 6% to 29%). In patients, SDI correlated negatively with left ventricular ejection fraction (r=-0.52, p<0.001), radial strain (r=-0.35, p=0.021), circumferential strain (r=-0.37, p=0.015) and circumferential SR (r=-0.43, p=0.004), but not with the cumulative anthracycline dose (p=0.82)., Conclusions: Impaired left ventricular myocardial deformation and mechanical dyssynchrony may exist in children after anthracycline therapy despite having normal left ventricular shortening fractions.

Background: The increasing data suggest an association between chronic right ventricular (RV) and left ventricular (LV) dysfunction. We sought to determine the effect of temporary interruption of long-term RV pacing on LV function and mechanical dyssynchrony in children and young adults with complete heart block., Methods: Twelve patients aged 20.0 + or - 7.4 years with congenital heart block (group I) and six patients aged 22.7 + or - 11.0 years with surgically acquired heart block (group II) with RV pacing were studied. The pacing rate was reduced to less than patient's intrinsic heart rate and maintained for 5 minutes. The LV ejection fraction (EF), three-dimensional systolic dyssynchrony index (SDI), two-dimensional global longitudinal strain and strain rate, and Doppler-derived isovolumic acceleration before and after interruption of RV pacing were compared., Results: The LVEF and GLS increased while QRS duration decreased after the pacing interruption in both the groups (all P < 0.05). While SDI decreased in both groups I (6.8 + or - 2.3%- 3.8 + or - 0.8%, P = 0.001) and II (9.2 + or - 4.1%-5.0 + or - 1.6%, P = 0.032), it remained higher in group II than in group I (P = 0.046) after the pacing interruption. The prevalence of LV dyssynchrony (SDI > 4.7%) decreased in group I (83%-25%, P = 0.006) but not in group II (67%-50%, P = 0.50). The %increase in LVEF correlated positively with %reduction of LV SDI (r = 0.80, P = 0.001)., Conclusions: Temporary interruption of chronic RV pacing acutely improves LV dyssynchrony and systolic function in children and young adults, the magnitude of which is greater in patients with congenital than those with surgically acquired heart block.

The aim of this study was to determine the effect of long-term right ventricular pacing on left ventricular (LV) mechanical dyssynchrony in children and young adults with congenital and acquired heart block. Eighteen patients aged 19 +/- 7 years with congenital heart block (group I), 9 aged 21 +/- 11 years with acquired heart block after congenital heart surgery (group II), and 15 healthy control subjects (group III) were studied. The LV volumes, ejection fractions, and systolic dyssynchrony index (SDI) values, as determined using 3-dimensional echocardiography, were compared among groups. Groups I (6.68 +/- 2.44%) and II (9.43 +/- 4.44%) had significantly greater SDI values than group III (3.88 +/- 0.63%) (p = 0.011 and p <0.001, respectively). The prevalence of LV mechanical dyssynchrony (SDI >5.14%, mean + 2 SDs of controls) in groups I and II was 72% and 67%, respectively. In 27 patients with right ventricular pacing, LV SDI values were correlated negatively with the LV ejection fractions (r = -0.74, p <0.001). The times to minimum regional volume were significantly longer in lateral, posterior, and inferior segments in group I and septal and inferior segments in group II compared to those in group III (p <0.05). Compared to patients without LV dyssynchrony, patients with LV dyssynchrony had lower LV ejection fractions (p <0.001), had shorter RR intervals (p <0.001), and tended to have dual-chamber pacing (p = 0.088) but had similar durations of pacing, QRS durations, and positions of pacing wires (epicardial vs endocardial). In conclusion, permanent right ventricular pacing in childhood has a negative effect on LV systolic function through the induction of mechanical dyssynchrony, the magnitude and pattern of which differ between congenital and acquired heart block.

This study aimed to test the hypothesis that right ventricular (RV) volume overload may result in left ventricular (LV) systolic dysfunction through induction of LV systolic dyssynchrony after tetralogy of Fallot (TOF) repair. Sixty patients with TOF repair were studied at 14.3 +/- 7.2 years after TOF repair. Real-time 3-dimensional echocardiographic data sets were acquired for measurement of LV and RV volumes and derivation of ejection fractions and pulmonary regurgitant volume. The LV systolic dyssynchrony index (SDI) was derived from the dispersion of time to minimum regional volume using a 16-segment model. The results were compared with those of 29 healthy controls. LV SDI was significantly higher in patients than controls (7.4% +/- 2.0% vs 3.0% +/- 0.9%, p <0.001). The prevalence of LV mechanical dyssynchrony (SDI >4.7%) in patients was 93% (95% confidence interval 87% to 100%). The time to minimum regional volume was significantly longer in all of the 6 basal segments and the midposterior segment (all p <0.05) in patients than controls. Multivariate analysis identified RV end-diastolic volume (beta = 0.58, p <0.001), LV ejection fraction (beta = -0.38, p <0.001), and LV end-diastolic volume (beta = 0.26, p = 0.002) as significant correlates of LV SDI. In conclusion, in patients after TOF repair, RV volume overload has a negative effect on LV systolic function through induction of global LV mechanical dyssynchrony.