The value of myocardial strain imaging in the evaluation of patients with repaired Tetralogy of Fallot: a review of the literature

Tetralogy of Fallot (ToF) is considered to be the most common, complex, cyanotic congenital heart disease (CHD) representing 7-10% of all congenital heart defects, whereas the patients with ToF are the most frequently operated in their early infancy or childhood. Cardiac magnetic resonance (CMR) consists a valuable imaging technique for the diagnosis and serial follow-up of CHD patients. Furthermore, in recent years, advanced echocardiography imaging techniques have come to the fore, aiming to achieve a complete and more accurate evaluation of cardiac function using speckle tracking imaging modalities. We conducted a review of the literature in order to assess the myocardial deformation of patients with repaired ToF (rToF) using echocardiographic and CMR parameters. Patients with rToF have impaired myocardial strain parameters, that are well standardized either with the use of speckle tracking echocardiography or with the use of CMR imaging. Subclinical left ventricular dysfunction (low GLS) and myocardial dyssynchrony are commonly identified in rToF patients. Impaired left atrium (LA) and right atrium (RA) mechanics are, also, a common finding in this study population, but the studies using atrial strain are a lot fewer than those with LV and RV strain. No studies using myocardial work were identified in the literature, as far as rToF patients are concerned, which makes it an ideal field for further investigation.

Impact of Right Ventricular Pressure Load After Repair of Tetralogy of Fallot

Background Right ventricular outflow tract (RVOT) stenosis after repair of tetralogy of Fallot has been linked with favorable right ventricular remodeling but adverse outcomes. The aim of our study was to assess the hemodynamic impact and prognostic relevance of right ventricular pressure load in this population. Methods and Results A total of 296 patients with repaired tetralogy of Fallot (mean age, 17.8±7.9 years) were included in a prospective cardiovascular magnetic resonance multicenter study. Myocardial strain was quantified by feature tracking technique at study entry. Follow-up, including the need for pulmonary valve replacement, was assessed. The combined end point consisted of ventricular tachycardia and cardiac death. A higher echocardiographic RVOT peak gradient was significantly associated with smaller right ventricular volumes and less pulmonary regurgitation, but lower biventricular longitudinal strain. During a follow-up of 10.1 (0.1-12.9) years, the primary end point was reached in 19 of 296 patients (cardiac death, n=6; sustained ventricular tachycardia, n=2; and nonsustained ventricular tachycardia, n=11). A higher RVOT gradient was associated with the combined outcome (hazard ratio [HR], 1.03; 95% CI, 1.00-1.06; P=0.026), and a cutoff gradient of ≥25 mm Hg was predictive for cardiovascular events (HR, 3.69; 95% CI, 1.47-9.27; P=0.005). In patients with pulmonary regurgitation ≥25%, a mild residual RVOT gradient (15-30 mm Hg) was not associated with a lower risk for pulmonary valve replacement. Conclusions Higher RVOT gradients were associated with less pulmonary regurgitation and smaller right ventricular dimensions but were related to reduced biventricular strain and emerged as univariate predictors of adverse events. Mild residual pressure gradients did not protect from pulmonary valve replacement. These results may have implications for the indication for RVOT reintervention in this population.

Risk Factors of Right Ventricular Dysfunction and Adverse Cardiac Events in Patients with Repaired Tetralogy of Fallot

Aim: This study evaluates the risk factors associated with right ventricular (RV) dilation and dysfunction leading to pulmonary valve replacement (PVR) or adverse cardiac events in repaired Tetralogy of Fallot (rToF) patients. Methods: Data from all rToF patients who underwent magnetic resonance imaging (MRI) evaluation at our hospital between February 2007 and September 2020 were collected. Results: Three hundred and forty-two patients (60% males, 42% older than 18 years), with a median age of 16 years (IQR 13–24) at the time of MRI, were included. All patients underwent complete repair at a median age of 8 months (IQR 5–16), while palliation was performed in 56 patients (16%). One hundred and forty-four patients (42%) subsequently received pulmonary valve replacement (PVR). At the multivariate analysis, male gender was an independent predictor for significant RV dilation, RV and left ventricular (LV) dysfunction. Transventricular ventricular septal defect (VSD) closure and previous palliation significantly affected LV function and RV size, respectively. Male gender and the transventricular VSD closure were independent predictors for PVR. Conclusions: Male gender and surgical history (palliation, VSD closure approach) significantly affected the long-term outcomes in rToF patients and should be taken into consideration in the follow-up management and in PVR timing in this patient population.

The impact of pulmonary regurgitation on right ventricular size and function in patients with repaired tetralogy of Fallot and additional haemodynamic abnormalities

Purpose

Right ventricular (RV) outflow tract obstruction (RVOTO) was demonstrated to be protective against RV dilatation in patients with repaired tetralogy of Fallot and chronic pulmonary regurgitation (PR). We hypothesised that the presence of additional haemodynamic abnormalities (more than mild tricuspid regurgitation, residual ventricular septal defect) reduces this protective association. Accordingly, we aimed to assess the impact of PR on RV size and function in this population.

Material and methods

Consecutive patients with additional haemodynamic abnormalities after tetralogy of Fallot (TOF) repair, who had undergone cardiovascular magnetic resonance, were included.

Results

Out of 90 patients studied, 18 individuals (mean age 32.5 ± 10.7 years, 72.2% males) met the inclusion criteria. There were no differences in RV volumes and ejection fraction between patients with and without RVOTO. Neither PR fraction (PRF) nor PR volume (PRV) correlated with RV end-diastolic volume (r = 0.36; p = 0.15 and r = 0.37; p = 0.14, respectively, for PRF and PRV) or RV end-systolic volume (r = 0.2; p = 0.42 and r = 0.19; p = 0.45, respectively, for PRF and PRV). Similarly, no significant correlations were observed between PRF or PRV and RV ejection fraction (r = –0.04; p = 0.87 and r = –0.03; p = 0.9, respectively).

Conclusions

Additional haemodynamic abnormalities are associated with the abolition of the protective effect of RVOTO on RV size. There was no significant relationship between measures of PR and RV volumes in patients after TOF repair with concomitant haemodynamic abnormalities. These abnormalities acted as confounding factors in the assessment of the impact of pulmonary regurgitation on RV size and function.

Biventricular myocardial adaptation in patients with repaired tetralogy of Fallot: Mechanistic insights from magnetic resonance imaging tissue phase mapping

BACKGROUND

The myocardial adaptive mechanism in patients with repaired tetralogy of Fallot (rTOF) is less understood. We aimed to investigate biventricular myocardial adaptive remodeling in rTOF patients.

METHODS

We recruited 32 rTOF patients and 38 age- and sex-matched normal controls. The pulmonary stenosis of rTOF patients was measured using catheterized pressure gradient between right ventricle (RV) and pulmonary artery (PGRVPA). rTOF patients with PGRVPA < 15 mmHg and ≥15 mmHg were classified as low pulmonary stenosis (rTOFlow, n = 19) and high pulmonary stenosis (rTOFhigh, n = 13) subgroups, respectively. Magnetic resonance imaging tissue phase mapping was employed to evaluate the voxelwise biventricular myocardial motion in longitudinal (Vz), radial (Vr), and circumferential (Vφ) directions.

RESULTS

The rTOFlow subgroup presented higher pulmonary regurgitation fraction than rTOFhigh subgroup (p < 0.001). Compared with the normal group, only rTOFlow subgroup presented a decreased RV ejection fraction (RVEF) (p < 0.05). The rTOFlow subgroup showed decreased systolic and diastolic Vz in RV and LV, whereas rTOFhigh subgroup showed such change only in RV. In rTOFlow subgroup, RVEF significantly correlated with RV systolic Vr (r = 0.56, p < 0.05), whereas LVEF correlated with LV systolic Vz (r = 0.51, p = 0.02). Prolonged QRS correlated with RV systolic Vr (r = -0.58, p < 0.01) and LV diastolic Vr (r = 0.81, p < 0.001). No such correlations occurred in rTOFhigh subgroup.

CONCLUSIONS

The avoidance of unfavorable functional interaction in RV and LV in rTOFhigh subgroup suggested that adequate pulmonary stenosis (PGRVPA ≥ 15 mmHg in this sereis) has a protective effect against pulmonary regurgitation.

Right Heart-Pulmonary Circulation Unit in Congenital Heart Diseases

The right ventricle plays a major role in congenital heart disease. This article describes the right ventricular mechanics in some selected congenital heart diseases affecting the right ventricle in different ways: tetralogy of Fallot, Ebstein anomaly, and the systemic right ventricle.

Right ventricular end-systolic area as a simple first-line marker predicting right ventricular enlargement and decreased systolic function in children referred for cardiac magnetic resonance imaging

AIM

To assess the accuracy of simple cardiovascular magnetic resonance imaging (CMR) parameters for first-line analysis of right ventricle (RV) dysfunction in children to identify those who require in-depth analysis and those in whom simple assessment is sufficient.

MATERIALS AND METHODS

Sixty paediatric CMR studies were analysed. The following CMR parameters were measured: RV end-diastolic and end-systolic area (4CH EDA and 4CH ESA), fractional area change (FAC), RV diameter in end-diastole (RVD1), tricuspid annular plane systolic excursion (TAPSE), and RV outflow tract diameter in end-diastole (RVOT prox). They were correlated with RV end-diastolic volume (RVEDVI) and RV ejection fraction (RVEF).

RESULTS

RVEDVI correlated best with 4CH ESA (r=0.85, <0.001) and EDA (r=0.82, <0.001). For RVEF only a moderate reverse correlation was found for 4CH ESA (-0.56, <0.001), 4CH EDA (-0.49, 0.001) and positive correlation for FAC (0.49, <0.001). There was no correlation between TAPSE and RVEF and only weak between RVD1 and RVEDVI. A 4CH ESA cut-off value of 8.5 cm²/m² had a very high diagnostic accuracy for predicting an enlarged RV (AUC=0.912, p<0.001, sensitivity 92.3%, specificity 79%) and a cut-off value of 10.5 cm²/m² was also a good predictor of depressed RV systolic function (AUC=0.873, p<0.001, sensitivity 83%, specificity 89%).

CONCLUSION

For routine screening in clinical practice, 4CH ESA seems a reliable and easy method to identify patients with RV dysfunction.

Longitudinal Validation of the Diastolic to Systolic Time-Velocity Integral Ratio as a Doppler-Derived Measure of Pulmonary Regurgitation in Patients with Repaired Tetralogy of Fallot

Pulmonary regurgitation (PR) is a common residual lesion and major determinant of outcome following surgical repair for tetralogy of Fallot. We sought to longitudinally study a previously described echocardiographic index as a correlate of PR measured by cardiac magnetic resonance imaging (CMR). We conducted a retrospective longitudinal study of patients with baseline and follow-up echocardiogram and CMR. The baseline studies were obtained as part of a research protocol, while the follow-up studies were performed for clinical purposes. On echocardiogram, the ratio of diastolic and systolic time-velocity integrals (DSTVI) in the main pulmonary artery was calculated. The Wilcoxon matched-pairs signed-rank test was used to test for individual changes in PR on echocardiogram and CMR. A linear regression of pulmonary valve regurgitant fraction (RF) was fit on DSTVI to identify clinically meaningful cut points of DSTVI. Thirty-five subjects were included, age at follow-up 18.3 ± 3.5 years. The follow-up between consecutive CMRs was a median time of 60 months (interquartile range 46-73). There was a moderate correlation between DSTVI and PR measured as RF by CMR (r = 0.62, p = 0.0001). A CMR RF of 20 and 40 % (the boundaries between mild/moderate and moderate/severe PR) corresponded with DSTVI of 0.52 and 0.79 (95 % CI 0.39; 0.66, and 0.69; 89), respectively. There was no significant change in either DSTVI (p = 0.61) or PR (p = 0.89) from baseline to follow-up. This study lends further credence to the DSTVI as an accurate reflection of PR. This index might become helpful in the routine echocardiographic assessment of PR. Further studies are needed to determine whether changes in RF by CMR result in changes in DSTVI.

Factors associated with right ventricular dilatation and dysfunction in patients with chronic pulmonary regurgitation after repair of tetralogy of Fallot: analysis of magnetic resonance imaging data from 218 patients

OBJECTIVE

The aim of the present study was to identify the factors associated with right ventricular (RV) dilatation and dysfunction in patients with chronic pulmonary regurgitation (PR) after repair of tetralogy of Fallot.

METHODS

From April 2002 to June 2013, 218 patients with repaired tetralogy of Fallot underwent magnetic resonance imaging; 165 (76%) underwent transannular repair and 36 (17%) underwent nontransannular repair. Linear regression analyses were used to identify the predictors for RV end-diastolic volume index (EDVI), end-systolic volume index (ESVI), and ejection fraction.

RESULTS

On univariable analysis, male sex, ventricular septal defect (VSD) closure through the right ventricle, larger pulmonary artery index, and greater PR fraction were associated with greater RV volume indexes. Multivariable analyses identified male sex (β = 17.55, P < .001 for RV EDVI; β = 14.08, P = .001 for RV ESVI), VSD closure through RV (β = 8.49, P = .048 for RV ESVI), longer interval since repair (β = 1.29, P = .014 for RV EDVI), and greater PR fraction (β = 1.92, P < .001 for RV EDVI; β = 1.38, P < .001 for RV ESVI) as independent predictors for greater RV volume indexes. On univariable analysis, male sex, VSD closure through the right ventricle, and greater PR fraction were associated with a lower RV ejection fraction. Multivariable analysis identified male sex (β = -3.10, P = .018), VSD closure through the right ventricle (β = -3.05, P = .020), and greater PR fraction (β = -0.27, P < .001) as independent predictors for a lower RV ejection fraction.

CONCLUSIONS

Male sex, VSD closure through the right ventricle, longer interval since repair, and greater PR fraction were independent predictors of RV dilatation after tetralogy of Fallot repair. Male sex, VSD closure through the right ventricle, and greater PR fraction were also independent predictors of RV dysfunction.

Early and 1-year outcome and predictors of adverse outcome following monocusp pulmonary valve reconstruction for patients with tetralogy of Fallot: A prospective observational study

Background and Objectives:

Repair of tetralogy of Fallot (TOF) with monocusp pulmonary valve reconstruction prevents pulmonary regurgitation (PR) for a variable period. Since postoperative outcome is governed by PR and right ventricular function, we sought to assess the severity of pulmonary regurgitation and right ventricular outflow (RVOT) gradient in the immediate postoperative period and at 1 year and attempted to identify the anatomical substrates responsible for adverse outcomes.

Methods:

The study included 30 patients. Transthoracic echocardiography was performed before surgery, within 5 days of surgery, and 1 year later. Presence and severity of PR, RVOT gradient, and residual branch pulmonary stenosis were assessed. Right ventricular and monocusp valve functions were studied.

Results:

Median age was 36.5 months (3-444 months). There were no deaths. Pulmonary regurgitation was mild in 18, moderate in 10, and severe in 2 patients immediately following surgery. At 1 year, 10 patients had severe PR and one had significant RVOT gradient. None of the variables like age, presence of supravalvar pulmonary branch stenosis, main pulmonary artery diameter, or mobility of monocusp valve was found to have any significant association with the progression of PR. McGoon index <1.5 showed a trend toward more PR, while patients with more residual RVOT gradient had lesser regurgitation.

Conclusions:

Repair of TOF with monocusp pulmonary valve reduces immediate postoperative PR. At 1 year, the monocusp valve underwent loss of function in a significant proportion and PR also progressed. This study could not identify any predictors of progression of PR, though patients with McGoon index <1.5 tended to have more PR while those with more outflow gradient had lesser PR.

Ventricular geometric characteristics and functional benefit of mild right ventricular outflow tract obstruction in patients with significant pulmonary regurgitation after repair of tetralogy of Fallot

BACKGROUND

Right ventricular (RV) outflow tract obstruction (RVOTO) might protect the RV from adverse remodeling caused by significant pulmonary regurgitation (PR) in patients with repaired tetralogy of Fallot (rTOF), but the underlying mechanisms and influences on exercise tolerance remain unclear. This study sought to investigate the impacts from mild RVOTO on ventricular remodeling and exercise capacity in rTOF.

METHODS

Eighty-five rTOF patients with a PR fraction ≥20% were assessed with cardiac magnetic resonance, cardiopulmonary exercise test, and echocardiography. Patients with a peak RVOT pressure gradient 20-50 mmHg were considered to have mild RVOTO (n = 29), while those with a gradient <20 mmHg had isolated PR (n = 56).

RESULTS

Comparing to patients with isolated PR, patients with combined PR and mild RVOTO had smaller RV and RVOT dimension, better RV and left ventricular (LV) ejection fraction (EF), and superior exercise capacity. PR severity and RV mass/volume ratio were similar between these 2 groups. LVEF coupled with RVEF only in patients with isolated PR. In multivariate analysis, smaller RVOT dimension was independently related to smaller RV dimension (P < .001) and higher RVEF (P = .005). Furthermore, mild RVOTO was independently associated with higher peak oxygen consumption (P = .014) and oxygen uptake efficiency slope (P = .005).

CONCLUSIONS

Patients with combined PR and mild RVOTO had better RV remodeling and exercise capacity compared to those with isolated PR. Our findings confirm the benefits from mild residual RVOTO support a policy of conservative RVOTO relief at repair.

Effect of right ventricular outflow tract obstruction on right ventricular volumes and exercise capacity in patients with repaired tetralogy of fallot

Patients with tetralogy of Fallot and combined right ventricular outflow tract obstruction (RVOTO) and pulmonary regurgitation (PR) have a less dilated right ventricular (RV) and better RV function compared with patients without RVOTO. It is not known whether RVOTO is associated with improved exercise capacity. We compared cardiac magnetic resonance imaging, echocardiography, and exercise tests in 12 patients with RVOTO (Doppler peak RVOT gradient ≥30 mm Hg) and 30 patients without RVOTO. RV end-systolic and end-diastolic volumes were smaller in patients with RVOTO compared with patients without RVOTO (50 ± 16 vs 64 ± 18 ml/m(2) and 117 ± 24 vs 135 ± 28 ml/m(2), respectively) and patients with RVOTO had a higher RV mass (52 ± 14 vs 42 ± 11 ml/m(2)), p <0.05. RV ejection fraction was marginally significantly different between both groups (58 ± 8% vs 53 ± 7%), p = 0.051. Degree of PR, left ventricular volumes, and function did not differ significantly between both groups. Peak oxygen uptake in patients with RVOTO was significantly lower (25 ± 3 vs 32 ± 8 ml/kg/min) than in patients without RVOTO, as was the percentage of predicted peak oxygen uptake (63 ± 7% vs 79 ± 14%), p <0.001. Multivariate analysis showed that the peak RVOT gradient was the only independent predictor of exercise capacity. In conclusion, exercise capacity is lower in patients with RVOTO compared with those without RVOTO despite a less dilated RV and comparable degree of PR. Therefore, exercise capacity may be of importance and should additionally be taken in consideration to RV volumes and function in patients with tetralogy of Fallot and PR.

Effect of branch pulmonary artery stenosis on right ventricular volume overload in patients with tetralogy of fallot after initial surgical repair

Right ventricular (RV) volume overload secondary to pulmonary regurgitation is common in patients after initial repair of tetralogy of Fallot (TOF) and is associated with adverse long-term outcomes. The objective of the present study was to determine the effect of branch pulmonary artery stenosis on the RV volume in patients with repaired TOF. We reviewed 178 cardiac magnetic resonance imaging studies in patients with repaired TOF. We defined bilateral stenosis as a Nakata index of ≤200 mm(2)/m(2) and concordant branch pulmonary artery cross-sectional area, unilateral stenosis as 1 branch pulmonary artery cross-sectional area ≤100 mm(2)/m(2) and 1 branch pulmonary artery cross-sectional area >100 mm(2)/m(2), and restrictive physiology as prograde main pulmonary artery diastolic flow. Of the 178 patients, 20 (11%) had bilateral stenosis, 47 (26%) unilateral stenosis, and 111 (63%) had no stenosis. The RV end-diastolic volume was lower in patients with bilateral (125 ± 27 ml/m(2)) or unilateral (131 ± 43 ml/m(2)) stenosis than in those without stenosis (149 ± 35 ml/m(2), p = 0.021 and p = 0.019, respectively). The main pulmonary artery regurgitant fraction was greater in patients without stenosis (47%, range 2% to 69%) than in those with bilateral (33%, range 9% to 59%; p = 0.009) or unilateral stenosis (40%, range 0% to 71%; p = 0.033). Restrictive physiology was more common in patients with bilateral (13 of 15, 87%) or unilateral (21 of 38, 55%) stenosis than in those without stenosis (28 of 85, 33%; p <0.001 and p = 0.017, respectively). In conclusion, in patients with repaired TOF, bilateral and unilateral branch pulmonary artery stenosis was associated with a greater main pulmonary artery regurgitant fraction and smaller RV end-diastolic volume than those in patients without stenosis, likely owing to the development of restrictive physiology. Branch pulmonary artery stenosis might effectively delay the referral for pulmonary valve replacement.

Beneficial effects of residual right ventricular outflow tract obstruction on right ventricular volume and function in patients after repair of tetralogy of Fallot

Preservation of the pulmonary valve, even at the expense of a mild residual stenosis, is the current surgical policy for the management of patients with tetralogy of Fallot (TOF). This study aimed to assess the long-term effect of a residual right ventricular outflow tract obstruction (RVOTO) on RV dimension and function. This study prospectively assessed 53 children (mean age, 13.4 ± 6.4 years) after repair of TOF using cardiovascular magnetic resonance imaging. Residual RVOTO on echocardiography was defined as a peak systolic RVOT gradient of 25 mmHg or higher. Patients with RVOTO (n = 29) had significantly less pulmonary regurgitation (25.2 ± 10.6 %) than patients without RVOTO (30.8 ± 9.3 %; p = 0.05) (n = 24). Compared with patients who had no RVOTO, children with RVOTO had significantly smaller RV end-diastolic volume (94.0 ± 2.6 vs 104.0 ± 20.7 ml/m(2); p < 0.05) and end-systolic volume (42.9 ± 20.0 vs 48.9 ± 13.2 ml/m(2); p < 0.05), whereas RV ejection fraction did not differ significantly between the two groups (55.5 ± 8.4 vs 54.0 ± 6.6 %). Restrictive physiology, assessed by late diastolic forward flow in the main pulmonary artery, was equally distributed within the two groups (31 vs 25 %; nonsignificant difference). According to the study data, residual RVOTO after repair of TOF does not affect RV function, whereas RV dimensions and the degree of pulmonary regurgitation are more favorable in the long-term follow-up evaluation of those patients. These results confirm the beneficial effects of the current strategy for repair of TOF.

The ratio of right ventricular volume to left ventricular volume reflects the impact of pulmonary regurgitation independently of the method of pulmonary regurgitation quantification

BACKGROUND

Previous studies have advocated quantifying pulmonary regurgitation (PR) by using PR volume (PRV) instead of commonly used PR fraction (PRF). However, physicians are not familiar with the use of PRV in clinical practice. The ratio of right ventricle (RV) volume to left ventricle volume (RV/LV) may better reflect the impact of PR on the heart than RV end-diastolic volume (RVEDV) alone. We aimed to compare the impact of PRV and PRF on RV size expressed as either the RV/LV ratio or RVEDV (mL/m(2)).

METHODS

Consecutive patients with repaired tetralogy of Fallot were included (n=53). PRV, PRF and ventricular volumes were measured with the use of cardiac magnetic resonance.

RESULTS

RVEDV was more closely correlated with PRV when compared with PRF (r=0.686, p<0.0001, and r=0.430, p=0.0014, respectively). On the other hand, both PRV and PRF showed a good correlation with the RV/LV ratio (r=0.691, p<0.0001, and r=0.685, p<0.0001, respectively). Receiver operating characteristic analysis showed that both measures of PR had similar ability to predict severe RV dilatation when the RV/LV ratio-based criterion was used, namely the RV/LV ratio>2.0 [area under the curve (AUC)(PRV)=0.770 vs AUC(PRF)=0.777, p=0.86]. Conversely, with the use of the RVEDV-based criterion (>170mL/m(2)), PRV proved to be superior over PRF (AUC(PRV)=0.770 vs AUC(PRF)=0.656, p=0.0028].

CONCLUSIONS

PRV and PRF have similar significance as measures of PR when the RV/LV ratio is used instead of RVEDV. The RV/LV ratio is a universal marker of RV dilatation independent of the method of PR quantification applied (PRF vs PRV).