Assessing Right Ventricular Strain in Children with Repaired Tetralogy of Fallot Using Speckle Tracking Imaging

0
0
0

Assessing Right Ventricular Strain in Children with Repaired Tetralogy of Fallot Using Speckle Tracking Imaging

Tetralogy of Fallot (TOF) is a congenital heart defect that has been surgically repaired since 1955. However, the initial repair methods had their own problems. For example, using a trans-annular right ventricular outflow tract patch led to long – standing pulmonary valve regurgitation and increased right ventricular (RV) volume, which could cause arrhythmias and sudden death. Later, pulmonary annulus preservation became a more common surgical strategy, but it might still result in a combination of pulmonary stenosis and regurgitation.

Clinicians are concerned about RV function decrease during long – term follow – up. Cardiac magnetic resonance imaging (CMR) is used to predict the right time for valve – sparing interventions. But regularly monitoring the progression of RV dysfunction in repaired tetralogy of Fallot (rTOF) patients with CMR is difficult. Echocardiographic screening tools can help estimate RV function and assist in determining when to use CMR.

RV dysfunction is an important clinical outcome indicator. Early detection of ventricular function is essential. However, evaluating RV function in rTOF patients with echocardiography is challenging due to the complex ventricle shape. Speckle tracking imaging (STI) offers alternative measurements for quantifying ventricular function. Although STI is used to evaluate left ventricular function in clinical practice, its value in evaluating RV function in pathological conditions is still in question. This study aimed to evaluate the change of RV deformation parameters in pediatric patients after TOF surgery in the early phase and investigate the value of STI.

Study Design and Participants

  • Participants: 75 consecutive rTOF subjects who had surgery between 2008 and 2016 were included. Data were collected from August 2016 to December 2017. Inclusion criteria: no change in medical therapy or surgical intervention. Exclusion criteria: post – surgical duration <1 year, arrhythmia, and poor – quality echocardiography. 57 patients' baseline data and surgery information were reviewed. 24 healthy controls (voluntarily recruited, no cardiovascular disease history or symptoms) were also included. The study was approved by the local ethics committee, and parents provided informed consent.
  • Imaging and Measurements:
    • 2D Echocardiography: For patients 70 frames/s. RV chamber measurements (apical four – chamber view for diameters, parasternal short – axis view for right ventricular outflow tract), functional parameters (fractional area change (FAC) in apical four – chamber view: FAC=(end – diastolic area – end – systolic area)/end – diastolic area; tricuspid annular plane systolic excursion (TAPSE) as the maximal excursion of the lateral annulus in apical four – chamber view). Diameter parameters were corrected for body surface area (BSA: BSA = 0.006×height + 0.0128×weight – 0.153). Pulmonary stenosis and regurgitation were assessed by measuring the pressure gradient of the pulmonary valve and the width of the regurgitation orifice.
    • 3D Echocardiography: Performed from the apical acoustic window using X5 – 1 (1 – 5MHz) and X7 – 2 (2 – 7MHz) transducers at a frame rate >25 frames/s. RV datasets were acquired. Off – line analysis was done with 3D right ventricular analysis software. Right ventricular three – dimensional ejection fraction (3D – EF): 3D – EF=(end – diastolic volume – end – systolic volume)/end – diastolic volume. Patients were divided into two groups (group I: EF ≥45%; group II: EF <45%) based on 3D – EF.
    • Myocardial Deformation Analysis: Automated tracking of myocardial deformation (strain and strain rate (SR)) was done offline using 2D speckle – tracking imaging. RV was divided into free wall and septum. Parameters assessed: global longitudinal strain (GLS), free wall longitudinal and transverse strain/SR, septum longitudinal and transverse strain/SR.

Statistical Analysis

  • Continuous data: mean ± standard deviation (SD). Categorical data: frequencies. Skew distribution data: median (quartile).
  • Between – group comparisons: independent t – tests for two groups, analysis of variance (ANOVA) for multiple groups.
  • Association analysis: multiple linear regression for 3D – EF and other characteristics.
  • Intra – and inter – observer agreement: assessed by repeated analysis in one – quarter of datasets (at least half a year after initial analysis), using Bland – Altman plot and coefficient of variation.

Results

  • Patient Characteristics: 39 males (68%) and 18 females (32%). Median age at surgery: 0.61 (0.49, 0.93) years. Mean postoperative duration: 3.8 ± 2.0 years. Mean age at study: 4.7 ± 2.3 years. Group I (3D – EFs ≥45%): 37 patients; group II (3D – EFs <45%): 20 patients. Control group: 24 normal children.
  • Echocardiographic Characteristics:
    • Diameters: RV diameters were larger in rTOF groups (no statistical difference between group I and group II). Pulmonary artery parameters were equal among three groups after BSA correction.
    • RV Function: All RV function parameters (except TAPSE) were lower in rTOF group than in control group. Group II had lower parameters than group I. Group II had more severe stenosis (width of regurgitation had no statistical difference). GLS was lower in group II than in group I, and both were lower than in normal children.
  • Predictive Model: Multiple linear regression model for 3D – EF: Y = 15.624+0.541×FAC–0.585×GLS, R² = 0.570. Standardized coefficients: FAC (0.557), GLS (- 0.380).
  • Segmental Myocardial Deformation:
    • Longitudinal: Longitudinal SR of free wall, longitudinal strain, and SR of septum in group II were lower than in healthy controls and further lower than in group I.
    • Transverse: Free wall and septum strain were larger in group I than in healthy controls (group II had no significant difference). Transverse SR of septum was larger in group I than in healthy controls. Septum transverse strain and SR were lower in group II than in group I.
  • Agreement Analysis: Intra – observer coefficients of variation: 3D – EF (8.0%), GLS (10.9%). Inter – observer coefficients of variation: 3D – EF (8.7%), GLS (14.3%).

Discussion

  • RV Function: RV function (3D – EF and GLS) was slightly decreased in rTOF patients. Transverse strain and SR were significantly increased in patients with normal EF, indicating potential preservation of RV myocardial function.
  • Post – surgical Duration: Mean post – surgical duration was 3.8 ± 2.0 years. RV enlargement was indicated by larger diameter parameters. Although some patients had NYHA class II, RV function parameters (except TAPSE) were worse in rTOF patients than in controls. Pulmonary valve stenosis was mild – to – moderate, and regurgitation width had no statistical difference between rTOF groups. Most rTOF patients had preserved RV function in the short term.
  • STI Analysis:
    • GLS: Decreased in rTOF patients. Lower GLS in group II implied worse EF. GLS is a reliable parameter for RV function, and decreased RV longitudinal strain may be a marker of early RV dysfunction (correlates with CMR – derived EF).
    • Segmental Parameters: RV segmental strain and SR analysis (divided into free wall and septum) showed different patterns. Transverse strain and SR increase in normal 3D – EF patients may be a pre – clinical compensative change. The mechanism is unclear but may be related to RV myocardial hypertrophy.
    • Variability: Higher variability in GLS measurements (due to difficulty in imaging RV free wall). But good reproducibility according to coefficients of variation. Intra – and inter – observer variation of GLS and 3D – EF measurements were considerable.

In conclusion, STI can reveal either RV dysfunction or preservation in rTOF patients with short – term post – surgical duration. Segmental parameters (transverse strain and SR) may be valuable for suggesting pre – clinical changes in RV function. STI can be used regularly for clinical monitoring.

[1] Gatzoulis MA, Balaji S, Webber SA, et al. Risk factors for arrhythmia and sudden cardiac death late after repair of tetralogy of Fallot: a multicentre study. Lancet 2000;356:975–981. doi: 10.1016/S0140 – 6736(00)02714 – 8. [2] Knauth AL, Gauvreau K, Powell AJ, et al. Ventricular size and function assessed by cardiac MRI predict major adverse clinical outcomes late after tetralogy of Fallot repair. Heart 2008;94:211–216. doi: 10.1136/hrt.2006.104745. [3] Rudski LG, Lai WW, Afilalo J, et al. Guidelines for the echocardiographic assessment of the right heart in adults: a report from the American Society of Echocardiography endorsed by the European Association of Echocardiography, a registered branch of the European Society of Cardiology, and the Canadian Society of Echocardiography. J Am Soc Echocardiogr 2010;23:685–713. doi: 10.1016/j.echo.2010.05.010. [4] Sabate RA, Bonnichsen CR, Reece CL, et al. Long – term follow – up in repaired tetralogy of fallot: can deformation imaging help identify optimal timing of pulmonary valve replacement? J Am Soc Echocardiogr 2014;27:1305–1310. doi: 10.1016/j.echo.2014.09.012. [5] Haddad F, Hunt SA, Rosenthal DN, Murphy DJ. Right ventricular function in cardiovascular disease, part I: Anatomy, physiology, aging, and functional assessment of the right ventricle. Circulation 2008;117:1436–1448. doi:10.1161/CIRCULATIONAHA.107.653576. [6] Toro KD, Soriano BD, Buddhe S. Right ventricular global longitudinal strain in repaired tetralogy of Fallot. Echocardiography 2016;33:1557–1562. doi: 10.1111/echo.13302. [7] Li Y, Xie M, Wang X, et al. Impaired right and left ventricular function in asymptomatic children with repaired tetralogy of Fallot by two – dimensional speckle – tracking echocardiography study. Echocardiography 2015;32:135–143. doi: 10.1111/echo.12581. [8] Bonnemains L, Stos B, Vaugrenard T, et al. Echocardiographic right ventricle longitudinal contraction indices cannot predict ejection fraction in post – operative Fallot children. Eur Heart J Cardiovasc Imaging 2012;13:235–242. doi: 10.1093/ejechocard/jer263. [9] Hayabuchi Y, Sakata M, Ohnishi T, Kagami S. A novel bilayer approach to ventricular septal deformation analysis by speckle tracking imaging in children with right ventricular overload. J Am Soc Echocardiogr 2011;24:1205–1212. doi: 10.1016/j.echo.2011.06.016. [10] Berganza FM, de Alba CG, Özcelik N, Adebo D. Cardiac magnetic resonance feature tracking biventricular two – dimensional and three – dimensional strains to evaluate ventricular function in children after repaired tetralogy of Fallot as compared with healthy children. Pediatr Cardiol 2017;38:566–574. doi: 10.1007/s00246 – 016 – 1549 – 6.

doi:10.1097/CM9.0000000000000126

Was this helpful?

0 / 0