Pulmonary Annulus Growth After the Modified Blalock-Taussig Shunt in Tetralogy of Fallot

Considerations in Timing of Surgical Repair in Tetralogy of Fallot

Certain aspects of the treatment of tetralogy of Fallot (TOF) repair remain controversial. The optimal timing of the elective repair of asymptomatic patients and the ideal strategy for managing symptomatic neonates and infants with TOF are still debated despite years of experience in TOF treatment. In this article, we discuss why a surgical correction at 3-6 months of age is likely the ideal time frame for the elective repair of TOF. We also elaborate on our strategy for managing symptomatic neonates and infants with TOF and why we prefer an early single-stage primary repair.

Pulmonary Annulus Growth Pattern in Patients with Tetralogy of Fallot Prior to Surgical Repair

Objectives

The size of the pulmonary valve annulus often determines the feasibility of pulmonary valve preservation at the time of intracardiac repair of Tetralogy of Fallot. Currently, there is limited available data regarding the growth pattern and the determining factors that contribute towards pulmonary valve annulus growth.

Methods

This retrospective study included patients who underwent surgical repair of Tetralogy of Fallot with or without prior palliation. These patients had an echocardiogram at the time of initial diagnosis and a second echocardiogram prior to intracardiac repair. The sizes of the pulmonary annulus, the right and left pulmonary arteries with z-scores were recorded. Patients with improvement in the pulmonary annulus z-scores between the 2 echocardiographic examinations were allocated in Group I (n = 46) and Group II (n = 68) were those with no improvement.

Results

A total of 114 patients were included in the study. The right and left pulmonary arteries size and z scores improved significantly between the 2 echocardiograms. Although the median size of the pulmonary annulus increased between the 2 echocardiograms (6 and 7.9 mm; P<0.001), there was no significant change in the z-score (-2.2, -2.34; P = 0.185). Multivariate logistic regression analysis showed that gender, blood group, presence of collaterals, and palliation with Blalock-Taussig shunt had no impact on the improvement in pulmonary annulus z-score.

Conclusion

In Tetralogy of Fallot, the pulmonary valve annulus z-score may not change significantly prior to the intracardiac repair. Although in certain subgroups there may be an improvement, there was no specific factor that could be identified and had an influence on this improvement.

Midterm prognosis following total correction of tetralogy of fallot in adult patients

Background

Tetralogy of Fallot is a common congenital heart disease characterized by cyanosis. The primary treatment approach involves corrective surgery typically performed within the first year of life to achieve complete resolution. However, certain patients may undergo surgery at an older age. This study seeks to assess the efficacy of surgery by examining the midterm outcomes of total correction of Tetralogy of Fallot when performed in older individuals.

Methods

This interventional-longitudinal study focused on patients who underwent complete surgery to correct tetralogy of Fallot at an advanced age of over 15 years. All of the participants were referred to the Shahid Rajaei Heart and Vascular Center, which is a referral center for congenital heart diseases in Iran, between 2010 and 2020. The surgical procedures for these patients involved primary total correction of tetralogy of Fallot or surgery following by shunt implantation. Prior to the surgery, the necessary information was gathered from the patients' medical records. The patients were then monitored over a 5-year period, during which they received regular check-ups from cardiologist with fellowship in adult congenital heart disease.

Results

A total of 94 participants were enrolled in the study, with an average age of 26.7 ± 9.6 years. Notably, the majority of the participants were male. The study reported a late mortality rate of 3.2%. Furthermore, 17 patients, constituting 18% of the cohort, underwent a secondary surgical procedure. This secondary surgery encompassed 14 cases of Pulmonary Valve Replacement (14.8%) and 3 cases of Ventricular Septal Defect repair (3.1%).

Conclusion

While the optimal age for total correction of Tetralogy of Fallot is conventionally considered to be within the first year of life, this study demonstrated that surgical intervention performed at a later stage of life can yield favorable midterm prognoses. It is imperative to emphasize that individuals unable to undergo surgery at the ideal age due to a multitude of factors should not be deprived of the potential benefits associated with surgical intervention.

Effect of Balloon Pulmonary Valvuloplasty on Growth of Pulmonary Annulus in Infants with Tetralogy of Fallot

Percutaneous balloon pulmonary valvuloplasty (PBPV) is an alternative intervention in infants with Tetralogy of Fallot (TOF). It can not only improve hypoxia but also promote pulmonary annulus (PA) growth. In this study, we evaluated the effect of PBPV on PA growth in infants with TOF. To eliminate the effect of the systemic to pulmonary shunt (SPS) that may promote PA growth, we divided TOF infants into 2 groups: group A, patients who underwent PBPV with or without other SPS, and group B, patients who attempted SPS but without PBPV. Sixty patients were included, 28 patients in group A and 32 patients in group B. Age at the time of intervention in group A (range, 0.4-5.4; median 1.4 months) was lower than that in group B (range, 2.3-7.7; median 4.8 months), p-value 0.02. The body weight in group A (range, 3-5.5; median 3.7 kg) was also lower than that in group B (range 4.1-6.4; median 5.9 kg), p-value 0.02. Echocardiographic data at the mean follow-up period of 37.2 months (3-88 months) in group A and 39.6 months (6-95 months) in group B demonstrated an increase in mean PA diameter from 5.0 ± 1.3 mm to 10.2 ± 2.9 mm, p-value < 0.001 in group A; and from 6.2 ± 2 mm to 9.5 ± 2.9 mm, p-value < 0.001 in group B. The median PA z-score increased from - 3.4SD (- 3.9 to - 2.6SD) to - 1.8SD (- 2.5 to - 0.8SD), with the p-value of 0.002 in group A; and increased from - 2.9SD (- 4.5 to - 1.3SD) to - 2.7SD (- 3.6 to - 1.4SD), with the p-value of 0.73 in group B. By using the PA z-score as the absolute value, there was a statistically significant increase in the PA z-score during follow-up in group A, but not in group B. Balloon pulmonary valvuloplasty in infants with TOF can facilitate the growth of the pulmonic annulus even after eliminating the effect of the systemic to pulmonary shunt.

Preserving the pulmonary valve in Tetralogy of Fallot repair: Reconsidering the indication for valve-sparing

BACKGROUND

Tetralogy of Fallot (TOF) repair is a frequent procedure, and although valve-sparing (VS) repair is preferred, determining which patients can successfully undergo this operation remains controversial. We sought to identify parameters to determine a selective, accurate indication for VS repair.

METHODS

We reviewed 71 patients (82%) undergoing VS repair. We analyzed hemodynamic data, intraoperative reports, and follow-up echocardiography results to identify acceptable indications. Patients requiring pulmonary valve (PV) reintervention versus no reintervention were compared.

RESULTS

PV annulus size at repair was z-score of -2.0 (-5.3, 1.3). Approximately half (51%) had a z-score less than -2. Cox regression results showed this was not a risk factor for reintervention (p = .59). Overall, 1-, 3-, 5-, and 10-year freedom from PV reintervention rates were 95.8%, 92.8%, 91% and 77.8%, respectively. Residual pulmonary stenosis (PS) at initial repair was relatively higher in the reintervention group compared with no reintervention group (40 [28, 51] mmHg vs. 30 [22, 37] mmHg; p = .08). For patients with residual PS, pressure gradient (PG) was consistent over time across both groups (PV reintervention: -3 [-15, 8] mmHg vs. no reintervention: 0 [-9, 8] mmHg). The risk of PV reintervention is 3.7-fold higher when the PG from intraoperative TEE is greater than 45 mmHg (p = .04).

CONCLUSIONS

Our review of the midterm outcomes of expanded indication for VS suggests intraoperative decision to convert to transannular patch is warranted if intraoperative postprocedure TEE PG is greater than 45 mmHg or RV pressure is higher than half of systemic pressure to prevent reintervention.

Multiscale modeling of a modified Blalock-Taussig surgery in a patient-specific tetralogy of Fallot

Tetralogy of Fallot (TOF) is a congenital heart anomaly that causes a drastic reduction in the oxygen level. In this study, we coupled a lumped-parameter model with a patient-specific three-dimensional (3D) model which included a modified Blalock-Taussig (MBT) shunt. By forming a closed loop, we investigated the effects of certain parameters on the flow rates and the pressures at different locations of the developed network. A local sensitivity analysis on an initial zero-dimensional (0D) closed-loop model was conducted. The 0D lumped parameter (LP) model was then refined based on the results of the multiscale 0D-3D model and the local sensitivity analysis was repeated for the refined 0D model. It was shown that the maximum pressure of the pulmonary bed had the highest sensitivity of 94% to the diameter of MBT shunt. We observed that the existence of the flow in the shunt during the diastole caused an elevated wall shear stress (WSS) in the pulmonary artery. In this work, we calculated the flow velocity and pressure field in a 3D patient-specific aorta with an MBT shunt, and then we used the results to increase the accuracy of our LP model to simulate numerous 0D simulations in a significantly shorter time, which is potentially applicable for medical decision-making.

Staged Repair of Tetralogy of Fallot: A Strategy for Optimizing Clinical and Functional Outcomes

BACKGROUND

This study evaluated the impact of a staged surgical strategy incorporating a modified Blalock-Taussig shunt (BTS) for tetralogy of Fallot (TOF) on pulmonary valve annulus (PVA) growth, the rate of valve-sparing repair (VSR) at the time of intracardiac repair (ICR), and long-term functional outcomes.

METHODS

This retrospective study included 330 patients with TOF who underwent ICR between 1991 and 2019, including 57 patients (17%) who underwent BTS. The mean follow-up period was 15.0±7.3 years. We compared the data of patients who underwent BTS and those who did not undergo BTS before ICR.

RESULTS

The median age and body weight before BTS were 71 (28-199) days and 4.3 (3.3-6.8) kg respectively. There were no in-hospital or interstage deaths after BTS. The PVA Z-scores of patients with BTS revealed significant growth after BTS (from -4.2±1.8 to -3.0±1.7, P<0.001). VSR was eventually performed in 207 (63%) patients, including 26 (46%) patients who underwent staged repair. The overall freedom from pulmonary regurgitation-related reintervention were 99.7%, 99.1%, and 95.8% at 1, 5, and 20 years, respectively.

CONCLUSIONS

A staged surgical strategy incorporating BTS as the first palliation for symptomatic patients resulted in no mortality. BTS may have contributed to the avoidance of primary transannular patch repair (TAP) and facilitated PVA growth; therefore, approximately half of the symptomatic neonates and infants were recruited for VSR. Staged repair may have led to functionally-reliable delayed TAP repair, thereby resulting in less surgical reinterventions.

Intermediate Outcomes of Staged Tetralogy of Fallot Repair

BACKGROUND

The optimal surgical strategy for tetralogy of Fallot (TOF) repair in neonates and young infants requiring early surgical intervention remains controversial. Our surgical center follows the uniform strategy of a staged approach with initial systemic-to-pulmonary artery shunt the majority of time when early surgical intervention is required. We characterized a contemporary cohort of patients with TOF with pulmonary stenosis (PS) undergoing staged repair in order to determine the rate of pulmonary valve-sparing repair (PVSR), growth of the pulmonary valve annulus and pulmonary arteries, postoperative morbidity and mortality, and need for reintervention.

METHODS

We retrospectively studied patients with TOF/PS who underwent staged repair from 2000 to 2017. Surgical details, postoperative course, and reinterventions were noted. Echocardiographic measurements and Z-score values of pulmonary valve annulus, main pulmonary artery (MPA), right pulmonary artery (RPA), and left pulmonary artery (LPA) diameters were evaluated.

RESULTS

Of the 59 patients with staged TOF/PS, PVSR was performed in 25 (42%). There was a 5% incidence of postoperative arrhythmia. The Z-scores of MPA, RPA, and LPA were significantly higher before complete repair when compared to before palliative shunt. The 5 and 10-year survival rates were both 93%, and the probability of freedom from reoperation at 5 and 10 years was 87% and 82%, respectively.

CONCLUSIONS

Staged repair of TOF in young symptomatic infants results in 42% receiving PVSR, pulmonary artery growth, low incidence of postoperative arrhythmia, and relatively low rate of reoperations.

Current outcomes and treatment of tetralogy of Fallot

Tetralogy of Fallot (ToF) is the most common type of cyanotic congenital heart disease. Since the first surgical repair in 1954, treatment has continuously improved. The treatment strategies currently used in the treatment of ToF result in excellent long-term survival (30 year survival ranges from 68.5% to 90.5%). However, residual problems such as right ventricular outflow tract obstruction, pulmonary regurgitation, and (ventricular) arrhythmia are common and often require re-interventions. Right ventricular dysfunction can be seen following longstanding pulmonary regurgitation and/or stenosis. Performing pulmonary valve replacement or relief of pulmonary stenosis before irreversible right ventricular dysfunction occurs is important, but determining the optimal timing of pulmonary valve replacement is challenging for several reasons. The biological mechanisms underlying dysfunction of the right ventricle as seen in longstanding pulmonary regurgitation are poorly understood. Different methods of assessing the right ventricle are used to predict impending dysfunction. The atrioventricular, ventriculo-arterial and interventricular interactions of the right ventricle play an important role in right ventricle performance, but are not fully elucidated. In this review we present a brief overview of the history of ToF, describe the treatment strategies currently used, and outline the long-term survival, residual lesions, and re-interventions following repair. We discuss important remaining challenges and present the current state of the art regarding these challenges.

Impact of Fetal Somatic Growth on Pulmonary Valve Annulus Z-Scores During Gestation and Through Birth in Patients with Tetralogy of Fallot

Previous studies have suggested reduced pulmonary valve annulus (PVA) growth and progression of pulmonary outflow obstruction in fetuses with tetralogy of Fallot (TOF). The goals of this study were to (1) investigate the trajectory of PVA growth in utero, and (2) compare two methods of z-score determination for fetal and postnatal PVA size by echocardiography in order to improve prenatal counseling for patients with TOF. Fetal echocardiograms (FE) at a single institution with a diagnosis of TOF between 8/2008 and 12/2015 were retrospectively reviewed. Patients included had at least 2 FEs and 1 immediate postnatal echocardiogram (TTE). Fetal and postnatal demographic, clinical, and echocardiographic data were collected. Fetal body surface area (BSA) was calculated by estimating fetal weight and height; z-scores were determined based on fetal gestational age (GA) and BSA for both FEs and TTEs. Fetal PVA z-scores by GA or BSA were then compared to postnatal PVA z-scores by BSA. Twenty-two patients with 44 FEs and 22 TTEs were included. GA at the first FE was 23 weeks ± 3.4 and 32 weeks ± 3.1 at the second FE. There was no difference in PVA z-scores (by BSA) between the first and second FE (p = 0.34), but a decrease in PVA z-scores (by BSA) between the second FE and TTE (- 1.6 ± 0.5 vs. - 2.0 ± 0.7; p = 0.01). Repeat comparison with fetal PVA z-scores indexed to GA revealed no difference in z-scores between the first and second FE, but an increase in PVA z-scores between the second FE (by GA) and TTE (by BSA) (- 4.1 ± 1.0 vs. - 2.0 ± 0.7; p < 0.0001). The rate of PVA growth between the two FEs (23 µm/day ± 9.8) and between the second FE and TTE (28 µm/day ± 42) remained comparable (p = 0.57); however, the rate of BSA increase was greater in later gestation (9 cm²/day ± 3 vs. 20 cm²/day ± 11; p = 0.001). In patients with TOF, the rate of PVA growth appears to remain consistent through gestation; however, somatic growth rate increases in late gestation. Fetal PVA z-scores indexed to GA are thus inaccurate in predicting postnatal PVA z-scores typically indexed to BSA. This observation should be considered during prenatal consultation and delivery planning.

Right Ventricular Outflow Tract Stenting in Tetralogy of Fallot Infants With Risk Factors for Early Primary Repair

Background—

Tetralogy of Fallot with cyanosis requiring surgical repair in early infancy reflects poor anatomy and is associated with more clinical instability and longer hospitalization than those who can be electively repaired later. We bridged symptomatic infants with risk factors for early primary repair by right ventricular outflow tract stenting (stent).

Methods and Results—

Four groups of tetralogy of Fallot with confluent central pulmonary arteries were studied: stent group (n=42), primary repair (aged <3 months) with pulmonary stenosis (early-PS group; n=44), primary repair (aged <3 months) with pulmonary atresia (early-PA group; n=49), and primary repair between 3 and 11 months of age (surg>3mo group; n=45). Stent patients had the smallest pulmonary arteries with a median (95% credible intervals) Nakata index (mm 2 /m 2 ) of 79 (66–85) compared with the early-PA 139 (129–154), early-PS 136 (121–153), and surg>3mo 167 (153–200) groups. Only stent infants required unifocalization of aortopulmonary collaterals (17%). Stent and early-PA infants had younger age and lower weight than early-PS infants. Stent infants had the most multiple comorbidities. Stenting allowed deferral of complete surgical repair to an age (6 months), weight (6.3 [5.8–7.0] kg), and Nakata index (147 [132–165]) similar to the low-risk surg>3mo group. The 3 early treatment groups had similar intensive care unit/hospital stays and high reintervention rates in the first 12 months after repair, compared with the surg>3mo group.

Conclusions—

Right ventricular outflow tract stenting of symptomatic tetralogy of Fallot with poor anatomy (small pulmonary arteries) and adverse factors (multiple comorbidities, low weight) relieves cyanosis and defers surgical repair. This allowed pulmonary arterial and somatic growth with clinical results comparable to early surgical repair in more favorable patients.