Noninvasive Perioperative Evaluation of Right Ventricular Function in Children With Tetralogy of Fallot

Right Ventricular Strain in Patients With Ductal-Dependent Tetralogy of Fallot

BACKGROUND

Right ventricular (RV) dysfunction is an independent predictor of poor outcomes in patients with tetralogy of Fallot (TOF), and global longitudinal strain (GLS) is a well-validated echocardiographic technique to measure RV function. Although trends in RV GLS have been examined in patients with TOF, they have not been studied specifically in those with ductal-dependent TOF, a group in which there is not a clear consensus on the best surgical strategy. The aim of this study was to assess the midterm trajectory of RV GLS in patients with ductal-dependent TOF, drivers of this trajectory, and differences in RV GLS between repair strategies.

METHODS

This was a retrospective two-center cohort study of patients with ductal-dependent TOF who underwent repair. Ductal dependence was defined as being initiated on prostaglandin therapy and/or undergoing surgical intervention on or before 30 days of life. RV GLS was measured on echocardiography preoperatively, early after complete repair, and at 1 and 2 years of age. RV GLS was trended over time and compared between surgical strategies and with control subjects. Mixed-effects linear regression models were used to evaluate the factors associated with changes in RV GLS over time.

RESULTS

Forty-four patients with ductal-dependent TOF were included in the study, of whom 33 (75%) underwent primary complete repair and 11 (25%) underwent staged repair. Complete TOF repair was performed at a median of 7 days in the primary-repair group and 178 days in the staged-repair group. RV GLS improved over time from post-complete repair echocardiography through 2 years of age (-17.4% [interquartile range, -15.5% to -18.9%] vs -21.5% [interquartile range, -18.0% to -23.3%], P < .001). However, compared with age-matched control subjects, patients had worse RV GLS at all time points. There was no difference in RV GLS between the staged and primary complete repair groups at 2-year follow-up. Shorter intensive care unit length of stay after complete repair was independently associated with improvement in RV GLS over time. Strain improved by 0.07% (95% CI, 0.01 to 0.12) for each fewer day in the intensive care unit (P = .03).

CONCLUSIONS

RV GLS improves over time among patients with ductal-dependent TOF, though it is consistently reduced compared with control subjects, suggesting an altered deformation pattern in patients with ductal-dependent TOF. There was no difference in RV GLS between the primary- and staged-repair groups at midterm follow-up, suggesting that repair strategy is not a risk factor for worse RV strain in the mid postoperative period. A shorter complete-repair intensive care unit length of stay is associated with an improved trajectory of RV GLS.

Right atrial function early after tetralogy of Fallot repair

Diastolic dysfunction after repair for Tetralogy of Fallot (TOF) is associated with adverse long-term outcomes. Right atrial (RA) mechanics as a proxy of right ventricular (RV) diastolic function in the early post-operative period after surgical repair for TOF has not been reported. We sought to evaluate RA and RV strain prior to hospital discharge after TOF repair and to identify important patient factors associated with strain using a machine learning method. Single center retrospective cohort study of TOF patients undergoing surgical repair, with analysis of RA and RV strain from pre-and post-operative echocardiograms. RA function was assessed by the peak RA strain, systolic RA strain rate, early diastolic RA strain rate and RA emptying fraction. RV systolic function was measured by global longitudinal strain. Pre- and post-operative values were compared using Wilcoxon rank sum test. Gradient boosted machine (GBM) models were used to identify the most important predictors of post-operative strain. In total, 153 patients were enrolled, median age at TOF repair 3.5 months (25th-75th percentile: 2.2- 5.2), mostly male (67%), and White (64.1%). From pre-to post-operative period, there was significant worsening in all RA parameters and in RV strain. GBM models identified patient, anatomic, and surgical factors that were strong predictors of post-operative RA and RV strain. These factors included pulmonary valve and branch pulmonary artery Z scores, birth weight, gestational age and age at surgery, pre-operative RV fractional area change and oxygen saturation, type of outflow tract repair, duration of cardiopulmonary bypass, and early post-operative partial arterial pressure of oxygen. There is significant worsening in RA and RV strain early after TOF repair, indicating early alteration in diastolic and systolic function after surgery. Several patient and operative factors influence post-operative RV function. Most of the factors described are not readily modifiable, however they may inform pre-operative risk-stratification. The clinical application of RA strain and the prognostic implication of these early changes merit further study.

Ventricular Myocardial Deformation Imaging of Patients with Repaired Tetralogy of Fallot

In patients with repaired tetralogy of Fallot (TOF), dysfunction of the right and left ventricles remains an important issue. Adverse right ventricular (RV) remodeling has been related to RV dilation secondary to pulmonary regurgitation, electromechanical dyssynchrony, and myocardial fibrosis. Left ventricular (LV) dysfunction is attributed among other factors to altered ventricular-ventricular interaction. Advancements in echocardiography and cardiac magnetic resonance imaging have enabled direct interrogation of myocardial deformation of both ventricles in terms of myocardial strain and strain rate. Emerging evidence suggests that myocardial deformation imaging may provide incremental information for clinical use. In children and adults with repaired TOF, there is a growing body of literature on the use of myocardial deformation imaging in the assessment of ventricular mechanics and its clinical and prognostic values. The present review aims to provide an overview of impairment in RV and LV mechanics, associations between RV and LV deformation, changes in ventricular deformation after pulmonary valve replacement, and associations between measures of RV and LV deformation and outcomes and to highlight the clinical translational potential of myocardial deformation imaging in patients with repaired TOF.

Longitudinal Changes in Right Ventricular Function in Tetralogy of Fallot in the Initial Years after Surgical Repair

BACKGROUND

Right ventricular (RV) dysfunction is associated with adverse long-term outcomes in patients with tetralogy of Fallot. Little is known about RV function in the first years after surgical repair. The aim of this study was to investigate perioperative changes in myocardial deformation using global longitudinal strain.

METHODS

A retrospective analysis of patients with surgically repaired tetralogy of Fallot was performed. Global longitudinal peak systolic RV strain was measured on early postoperative echocardiograms, two subsequent postoperative echocardiograms through 2 years postoperatively, and preoperative echocardiograms, when available. Preoperative and late follow-up strain was compared with strain in 0- to 8-month-old and 1- to 4-year-old control subjects, respectively.

RESULTS

Forty-seven patients were included. Compared with postoperative strain (7 ± 7 days postoperatively), strain at follow-up 1 (8.3 ± 4 months postoperatively) was significantly improved (-12.3 ± 3.3% vs -18.8 ± 2.5%, P < .001), with no additional improvement 23.2 ± 6 months postoperatively (-18.8 ± 2.5% vs -19.8 ± 3.1%, P = .12). Postoperative strain was worse than preoperative strain (n = 25, -12.5 ± 3.6% vs -18.4 ± 2.9%, P < .001). Compared with control subjects, preoperative strain was similar (-19.3 ± 3.8% vs -18.4 ± 2.9%, P = .30), though late follow-up strain was significantly worse (-27.7 ± 2.8% vs -19.8 ± 3.1%, P < .001).

CONCLUSIONS

RV global longitudinal strain worsens in the early postoperative period following surgical repair of tetralogy of Fallot but recovers through 2 postoperative years. Despite recovery to preoperative values, the presence of RV dysfunction compared with control subjects suggests that long-term dysfunction may begin early. The trajectory of RV dysfunction through the later years needs further study.

NT-proBNP as Marker of Ventricular Dilatation and Pulmonary Regurgitation After Surgical Correction of Tetralogy of Fallot: A MRI Validation Study

The goal of this study is to evaluate whether NT-proBNP plasma levels may help as a screening biomarker for monitoring right ventricular dilatation, pulmonary regurgitation and the onset of heart failure in patients with repaired Tetralogy of Fallot. Our single-centre observational prospective study involved 43 patients (15.1 years, SD = 8) with corrected Tetralogy of Fallot. Data collection included: clinical parameters (electrocardiogram, chest X-ray, NYHA scale, time since last surgery), biochemistry (NT-proBNP levels) and MRI values (ventricular volumetry, pulmonary flow assessment). Mean time since last surgery was 13.5 years (SD = 7.8). There was a statistically significant correlation between the NT-proBNP levels (187.4 pg/ml, SD = 154.9) and right ventricular dilatation for both the right ventricular end-diastolic volume (124.9 ml/m², SD = 31.2) (Pearson = 0.19, p < 0.01) and end-systolic volume (56.1 ml/m², SD = 18.8) (Pearson = 0.21, p < 0.01) and also with the pulmonary regurgitation fraction (36.5%, SD = 16, Pearson = 0.12, p < 0.01). No significant correlation was found between NT-proBNP and right ventricular ejection fraction (54.6%, SD = 10.6, Pearson = -0.07), left ventricular ejection fraction (59.9%, SD = 7.1, Pearson = -0.18) or any clinical parameters. The receiver operating curve analysis evidenced that a NT-proBNP cut-off value above 133.2 pg/ml predicted the presence of dilated right ventricular end-diastolic and end-systolic volumes over centile 95 (sensitivity 82 and 83% and specificity 93 and 79%, respectively). In conclusion, in patients with surgically corrected Tetralogy of Fallot, NT-proBNP levels correlate with right ventricular dilatation and the degree of pulmonary regurgitation. Ambulatory determination of NT-proBNP might be an easy, readily available and cost-effective alternative for MRI follow-up evaluation of these patients.

Application of Real-Time Three-Dimensional Echocardiography to Evaluate the Pre- and Postoperative Right Ventricular Systolic Function of Patients with Tetralogy of Fallot

Tetralogy of Fallot (ToF) can be challenging for clinicians to both diagnose and treat, given the multiple heart defects that are by definition associated with the illness. This study investigates the value of real-time three- dimensional echocardiography (RT-3DE) in evaluating the pre-and postoperative right ventricular systolic function of patients with tetralogy of Fallot. A total of 41 ToF patients were divided into two groups: the child group (CG) and the adult group (AG) according to age. The right ventricular end-diastolic volume (RVEDV), right ventricular end-systolic volume (RVESV), and the right ventricular ejection fraction (RVEF) of ToF patients were measured before surgery, 7 days, and 3 months after the surgery. The correlation between the preoperative Nakata index and RVEF was then analyzed. Compared with the RVEDV and RVESV prior to surgery, those of the postoperative 7-day and 3-month were not statistically significant (p > 0.05). However, RVEF decreased, and the difference was statistically significant (p < 0.05). The differences in RVEDV, RVESV, and RVEF between postoperative 3-month and 7-day were not significant (p > 0.05). Compared with the pre-and postoperative RVEDV and RVESV of CG, those of AG increased. However, RVEF decreased, and the differences were statistically significant (p < 0.05). Our study indicated that the correlation between preoperative Nakata index and RVEF was good. Ultimately, we did confirm that RT-3DE can quantitatively evaluate the right ventricular volume and systolic function of ToF patients, thereby providing clinical significance in determining postoperative efficacy and prognosis evaluation.

KEY WORDS

Echocardiography; Right; Tetralogy of Fallot; Three-dimensional; Ventricular function.

How best to assess right ventricular function by echocardiography

Right ventricular function is a crucial determinant of long-term outcomes of children with heart disease. Quantification of right ventricular systolic and diastolic performance by echocardiography is of paramount importance, given the prevalence of children with heart disease, particularly those with involvement of the right heart, such as single or systemic right ventricles, tetralogy of Fallot, and pulmonary arterial hypertension. Identification of poor right ventricular performance can provide an opportunity to intervene. In this review, we will go through the different systolic and diastolic indices, as well as their application in practice. Quantification of right ventricular function is possible and should be routinely performed using a combination of different measures, taking into account each disease state. Quantification is extremely useful for individual patient follow-up. Laboratories should continue to strive to optimise reproducibility through quality improvement and quality assurance efforts in addition to investing in technology and training for new, promising techniques, such as three-dimensional echocardiography.