EDUCATIONAL SERIES IN CONGENITAL HEART DISEASE: Tetralogy of Fallot: diagnosis to long-term follow-up

Management of Fallot's Uncorrected Tetralogy in Adulthood: A Narrative Review

The majority of cyanotic congenital cardiac defects are caused by the tetralogy of Fallot. Some symptoms include a biventricular connection of the aortic root, right ventricular hypertrophy, blockage of the right ventricular outflow tract, and a ventricular septal defect. Our understanding of tetralogy of Fallot (TOF) has significantly advanced since it was first described in 1888, and early diagnosis has led to improved surgical management and increased life expectancy. Adults with unrepaired and repaired TOF present with a range of late complications, including heart failure, the need for re-interventions, and late arrhythmias. Right ventricular (RV) failure, often caused by chronic pulmonary regurgitation, is a significant cause of heart failure in patients with TOF. Current treatment options are limited, and mainstay surgical procedures such as pulmonary-valve replacement (PVR), trans-annular repair (TAR), or infundibular widening repair have not shown a significant reduction in preventing right ventricular (RV) failure or death. Here, we explain the mechanisms of RV failure in ToF, chronic pulmonary regurgitation, heart failure, and secondary polycythemia. HF management in untreated adults is discussed. The progression of the disease, as well as complications, are also discussed. The treatment plan and the need to investigate the best management approach for this unsolved problem are included. This review aims to fill the knowledge gaps and supply valuable information regarding mechanisms of RV failure, chronic pulmonary regurgitation, and secondary polycythemia. To summarize, a new combat strategy must be found to battle RVF, and a more profound vision of these mechanisms is required. If it is not corrected, it will be one of the future research lines that will contribute to designing more efficacious treatment techniques for adults with TOF.

Transcatheter-Based Interventions for Tetralogy of Fallot Across All Age Groups

Tetralogy of Fallot (TOF) is the most common form of cyanotic congenital heart disease. Palliative procedures, either surgical or transcatheter, aim to improve oxygen saturation, affording definitive procedures at a later stage. Transcatheter interventions have been used before and after surgical palliative or definitive repair in children and adults. This review aims to provide an overview of the different catheter-based interventions for TOF across all age groups, with an emphasis on palliative interventions, such as patent arterial duct stenting, right ventricular outflow tract stenting, or balloon pulmonary valvuloplasty in infants and children and transcatheter pulmonary valve replacement in adults with repaired TOF, including the available options for a large, dilated native right ventricular outflow tract.

The Nakata index and McGoon ratio: correlation with the severity of pulmonary regurgitation after the repair of paediatric tetralogy of Fallot

BACKGROUND

Pulmonary regurgitation is the most common complication after the complete repair of tetralogy of Fallot, and severe pulmonary regurgitation after surgery requires pulmonary valve replacement. In this retrospective observational, cross-sectional study, we included a total of 56 children aged 6 years or younger who underwent complete repair of TOF at Shahid Rajaei Cardiovascular Medical and Research Center in Tehran, Iran. Preoperative dual-source computed tomography was used to measure the McGoon ratio and Nakata index. The patients were divided into two groups based on the severity of postoperative pulmonary regurgitation, as estimated by trans-thoracic echocardiography: the severe pulmonary regurgitation group and the non-severe pulmonary regurgitation group. The McGoon ratio and Nakata index were then compared between the two groups.

RESULTS

When comparing the two groups, we found that the corrected right pulmonary artery diameter, main pulmonary artery diameter, and McGoon ratio in the non-severe pulmonary regurgitation group were higher than in the severe pulmonary regurgitation group. However, none of these differences were statistically significant. Additionally, other variables, including the corrected left pulmonary artery diameter and Nakata index, showed higher measurements in children with severe pulmonary regurgitation, but again, the differences were not statistically significant.

CONCLUSIONS

This study indicates that pulmonary arteries diameter, Nakata index, and McGoon ratio were not significantly correlated with the severity of pulmonary regurgitation after the complete repair of tetralogy of Fallot.

Detection of tracheal branching with computerized tomography: The relationship between the angles and age-gender

BACKGROUND

The data obtained on the anatomical knowledge of the tracheobronchial system can be used for diagnosis, treatment and interventional interventions in areas such as anesthesia, thoracic surgery, pulmonary physiology.

AIM

To determine the tracheobronchial branching angles in pediatric and adult populations by using the multislice computed tomography (CT) and minimum intensity projection (MinIP) technique, which is a non-invasive method.

METHODS

Our study was carried out retrospectively. Patients who underwent contrast and non-contrast CT examination, whose anatomically and pathophysiologically good tracheobronchial system and lung parenchyma images were obtained, were included in the study. Measurements were made in the coronal plane of the lung parenchyma. In the coronal plane, right main bronchus-left main bronchus angle, right upper lobe bronchus-intermedius bronchus angle, right middle lobe bronchus-right lower lobe bronchus angle, left upper lobe bronchus-left lower lobe bronchus angle were measured.

RESULTS

The study population consisted of 1511 patients, 753 pediatric (mean age: 13.4 ± 4.3; range: 1-18 years) and 758 adults (mean age: 54.3 ± 17.3; range: 19-94 years). In our study, tracheal bifurcation angle was found to be 73.3° ± 13.7° (59.6°-87°) in the whole population. In the pediatric group, the right-left main coronal level was found to be higher in boys compared to girls (74.6° ± 12.9° vs 71.2° ± 13.9°, P = 0.001). In the adult group, the right-left main coronal level was found to be lower in males compared to females (71.9° ± 12.9° vs 75.8° ± 14.7°, P < 0.001).

CONCLUSIONS

Our study, with the number of 1511 patients, is the first study in the literature with the largest number of patient populations including pediatric and adult demographic data, measuring the angle values of the tracheobronchial system using multislice CT and MinIP technique. Study data will not only be a guide during invasive procedures, but it can also guide studies to be done with imaging methods.

Energy metabolism disorder dictates chronic hypoxia damage in heart defect with tetralogy of fallot

Background

Tetralogy of Fallot (TOF) belongs to cyanotic heart damage, which is the most common in clinic. In the chronic myocardial hypoxia injury related to TOF, the potential molecular mechanism of cardiac energy metabolism remains unclear.

Materials and methods

In our study, microarray transcriptome analysis and metabonomics methods were used to explore the energy metabolism pathway during chronic hypoxia injury. The gene expression omnibus (GEO) dataset GSE132176 was obtained for analyzing the metabolic pathways. The clinical samples (right atrial tissues) of atrial septal defect (ASD) and TOF were analyzed by metabonomics. Next, we screened important pathways and important differential metabolites related to energy metabolism to explore the pathogenesis of TOF.

Results

Gene set enrichment analysis (GSEA) indicated that fructose 6-phosphate metabolic process, triglyceride metabolic process, and et al. were significantly enriched. Gene set variation analysis (GSVA) results showed that significant difference of ASD group and TOF group existed in terpenoid metabolic process and positive regulation of triglyceride metabolic process. Pathways with significant enrichment (impact > 0.1) in TOF were caffeine metabolism (impact = 0.69), sphingolipid metabolism (impact = 0.46), glycerophospholipid metabolism (impact = 0.26), tryptophan metabolism (impact = 0.24), galactose metabolism (impact = 0.11). Pathways with significant enrichment (impact > 0.1) in ASD are caffeine metabolism (impact = 0.69), riboflavin metabolism (impact = 0.5), alanine, aspartate and glutamate metabolism (impact = 0.35), histidine metabolism (impact = 0.34) and et al.

Conclusion

Disturbed energy metabolism occurs in patients with TOF or ASD, and further investigation was needed to further clarify mechanism.

320 cardiac MDCT angiography in preoperative assessment of TOF and its variants: Does it worth it?

Background

Tetralogy of Fallot is the most common cyanotic congenital heart disease encountering a large spectrum of anatomical presentations with differing surgical approaches, and long-term outcomes ranging from ventricular septal defect with limited aortic overriding and mild pulmonary obstruction to a critical form of VSD and pulmonary atresia. TOF variants include PA/VSD, TOF/CAVC, TOF/DORV and TOF with absent pulmonary valve. Also, it may be accompanied with many associated intracardiac and extracardiac anomalies that may be of value when imaging and planning the surgical procedure.

Results

Our study included 22 cases of classic TOF, 18 with PA/VSD (12 were of type A, 5 were of type B and 1 was of type C), 3 with TOF/CAVC and 7 TOF/DORV. Sub-valvular RVOTO was detected in 94% of patients. A statistically significant difference was depicted between Echocardiography and MDCT in detecting supravalvular RVOTO, however no statistically significant difference was found in sub-valvular and valvular RVOTO detection. MDCT could efficiently characterize pulmonary arterial tree with statistically significant difference between both Echocardiography and MDCT in assessment of main, right and left pulmonary arteries with P value = 0.036,0.014 and 0.023 respectively. With calculation of Mc-Goon ratio in all patients, it was favorable (> 1.2) in 33 patients (66%). MDCT entailed 19 patients with PDA versus 15 depicted by Echocardiography and 25 MAPCAs per 11patients compared 8 MAPCAs per 7 patients detected by Echocardiography. Right sided aortic arch was found in 10 patients and 24 patients showed abnormal branching pattern. Coronary artery abnormalities were identified in eight patients. MDCT showed 100% sensitivity and 100% specificity in depicting aortic, coronary and other associated extracardiac vascular anomalies.

Conclusion

MDCT offers comprehensive anatomical assessment of TOF, and its variants providing superiority over echocardiography and comparable results to cardiac catherization with 100% sensitivity and specificity in evaluation of associated extracardiac vascular anomalies as well as pulmonary arteries characterization. It is worth using MDCT routinely in combination with echocardiography for the preoperative assessment of TOF and its variants representing a less invasive option than conventional catherization with lower radiation exposure.

CMR parameters and CMR-FT in repaired tetralogy of Fallot

Background

Repaired tetralogy of Fallot patients develops postoperative complications that are in need for follow-up and re-intervention in some circumstances. CMR myocardial feature tracking is a novel method that allows quantification of bi-atrial and bi-ventricular mechanics of deformation. So our aim is to assess the added value of cardiac magnetic resonance imaging and its advanced feature tracking analysis in evaluation of repaired tetralogy of Fallot patients.

Results

CMR was done with feature tracking post-processing analysis for 56 patients with repaired tetralogy of Fallot and 56 healthy volunteers. The commonest postoperative complications in patients with repaired tetralogy of Fallot are in the following order: pulmonary regurgitation with subsequent right ventricular dilatation and tricuspid regurgitation followed by pulmonary stenosis, right ventricular dysfunction, right ventricular outflow tract dilatation, left ventricular dysfunction, aortic and mitral regurgitation and residual ventricular septal defect. All right ventricular volumes were found to be significantly increased compared to those of the healthy volunteers (p value < 0.001) also left ventricular end-diastolic and end-systolic volumes indexed were found to be increased in those patients compared to healthy volunteers (p value < 0.001). Right and left ventricular function were significantly lower in those patients compared to controls. Bi-ventricular CMR-FT indices and right atrial global longitudinal strain were found to be significantly lower in patients with repaired tetralogy of Fallot compared to controls. Right atrium global longitudinal strain was found to be significantly correlated with right ventricular global longitudinal strain and did not correlate with right ventricular ejection fraction and end-diastolic volume indexed; p value < 0.001, 0.109 and 0.565, respectively. Right ventricular global circumferential strain was found to be significantly increased in patients with right ventricular outflow tract obstruction compared to those without obstruction (− 16.26 ± 4.27% vs. − 12.2 ± 3.78%, respectively). Pulmonary regurgitant volume indexed was found to be significantly related to right ventricle longitudinal strain (p value 0.027).

Conclusion

Biventricular volumetric measures are increased in patients with repaired tetralogy of Fallot compared to controls; however, feature tracking parameters for both ventricles and right atrium are lower in those patients compared to controls.

Genetic insights into non-syndromic Tetralogy of Fallot

Congenital heart defects (CHD) include structural abnormalities of the heart or/and great vessels that are present at birth. CHD affects around 1% of all newborns worldwide. Tetralogy of Fallot (TOF) is the most prevalent cyanotic congenital cardiac abnormality, affecting three out of every 10,000 live infants with a prevalence rate of 5-10% of all congenital cardiac defects. The four hallmark characteristics of TOF are: right ventricular hypertrophy, pulmonary stenosis, ventricular septal defect, and overriding aorta. Approximately 20% of cases of TOF are associated with a known disease or chromosomal abnormality, with the remaining 80% of TOF cases being non-syndromic, with no known aetiology. Relatively few TOF patients have been studied, and little is known about critical causative genes for non-syndromic TOF. However, rare genetic variants have been identified as significant risk factors for CHD, and are likely to cause some cases of TOF. Therefore, this review aims to provide an update on well-characterized genes and the most recent variants identified for non-syndromic TOF.

Tetralogy of Fallot in the nascent open-heart surgical era in a tertiary hospital in south-west Nigeria: lessons learnt

BACKGROUND

Tetralogy of Fallot (TOF) is the leading cyanotic congenital heart disease. We commenced open-heart surgery at the Obafemi Awolowo University Teaching Hospitals Complex (OAUTHC), Ile-Ife, Nigeria in 2016.

OBJECTIVES

To review the incidence, pattern, management and treatment outcomes of TOF at the OAUTHC.

METHODS

A retrospective audit was undertaken of hospital records, including echocardiograms of patients with TOF seen from January 2016 to February 2020 at the Paediatric Cardiology Unit, OAUTHC.

RESULTS

Seventy-two patients (37 boys and 35 girls) aged 0.17-22 years had TOF. Thirty-three (45.8%) had surgery; 31 (93.9%) corrective surgery and two (6.1%) a modified Blalock-Taussig shunt. Complications following surgery included cardiac dysfunction, post-transfusion malaria, pulmonary regurgitation, pericardial effusion and death (15%). Thirty-nine (54.2%) patients had conservative medical management. Complications included polycythaemia and thrombotic stroke, and 14 (35.9%) patients died.

CONCLUSIONS

TOF is associated with significant morbidity and mortality in developing countries. Early and safe corrective surgery is desirable.

Complex adult congenital heart disease on cross-sectional imaging: an introductory overview

Congenital heart disease is the most common group of congenital pathology. Over the past few decades, advances in surgical treatment have resulted in a rising population of adult patients with repaired complex congenital heart disease. Although the quality of life has greatly improved, a significant proportion of morbidities encountered in clinical practice is now seen in adults rather than in children. These patients often have significant haemodynamic pathophysiology necessitating repeat intervention. CT and MRI are excellent imaging modalities, which help elucidate potential complications that may need urgent management. Although imaging should be performed in specialised centres, occasionally patients may present acutely to emergency departments in hospitals with little experience in managing potentially complex patients. The purpose of this article is to provide an introductory overview to the radiologist who may not be familiar with complex congenital heart disease in adult patients. This educational review has three main sections: (1) a brief overview of the post-operative anatomy and surgical management of the most common complex conditions followed by (2) a discussion on CT/MRI protocols and (3) a review of the various complications and their CT/MRI findings.

Tricuspid annular abnormalities following different surgical strategies in adults with corrected tetralogy of Fallot (Results from the CSONGRAD Registry and MAGYAR-Path Study)

BACKGROUND

Although there is an increasing number of patients with corrected tetralogy of Fallot (cTOF), who reach adulthood due to recent successful surgical procedures, some of them suffers from late complications, including functional tricuspid regurgitation (FTR). The purpose of the present study was to examine tricuspid annular (TA) abnormalities in adult cTOF patients and their relationship right atrial (RA) volumes respecting the cardiac cycle assessed by three-dimensional speckle-tracking echocardiography (3DSTE). Moreover, the effect of different surgical procedures on TA morphologic and functional parameters was examined as well.

METHODS

The study comprised 24 cTOF patients (32.8±13.5 years, 9 males) in which early palliative surgery and late total correction were performed in 12 cases (pcTOF), while early total reconstruction was performed in 12 subjects (etrTOF). Their results were compared to those of 33 matched healthy adults (36.7±7.2 years, 15 males).

RESULTS

Dilated end-systolic and end-diastolic TA morphologic parameters and their body surface area-indexed counterpart could be detected in cTOF patients as compared to that of controls. TA fractional area change and TA fractional shortening proved to be reduced in cTOF patients as well as in etrTOF and pcTOF patients compared to controls. None of the TA morphologic and functional parameters showed any differences between etrTOF and pcTOF patients. Increased maximum, preatrial contraction and minimum RA volumes could be detected in cTOF patients compared to controls, which correlated with TA dimensions.

CONCLUSIONS

TA is dilated with reduced function in adult patients with cTOF. TA dilation is related to RA volumes. etrTOF and pcTOF patients have similar TA dimensions and TA functional properties.

KEYWORDS

Fallot; tricuspid annulus; three-dimensional (3D); speckle-tracking; echocardiography.

Diagnosis and treatment of adults with congenital heart disease

Approximately 50 million adults worldwide have known congenital heart disease (CHD). Among the most common types of CHD defects in adults are atrial septal defects and ventricular septal defects followed by complex congenital heart lesions such as tetralogy of Fallot. Adults with CHDs are more likely to have hypertension, cerebral vascular disease, diabetes and chronic kidney disease than age-matched controls without CHD. Moreover, by the age of 50, adults with CHD are at a greater than 10% risk of experiencing cardiac dysrhythmias and approximately 4% experience sudden death. Consequently, adults with CHD require healthcare that is two- to four-times greater than adults without CHD. This paper discusses the diagnosis and treatment of adults with atrial septal defects, ventricular septal defects and tetralogy of Fallot.

Mitral annulus is enlarged and functionally impaired in adult patients with repaired tetralogy of Fallot as assessed by three-dimensional speckle-tracking echocardiography-results from the CSONGRAD Registry and MAGYAR-Path Study

Background

Fibrous mitral annulus (MA) is an important part of the mitral valve having a role in forwarding blood from the left atrium (LA) to the left ventricle (LV). MA can be assessed by three-dimensional speckle-tracking echocardiography (3DSTE) respecting the cardiac cycle. The present study was designed to test whether repaired Tetralogy of Fallot (TOF) is associated with morphological and functional alterations of the MA. The role of the type of treatment (early total reconstruction vs. early palliation, late correction) was also assessed.

Methods

The study population consisted of 29 consecutive adults repaired TOF patients (mean age: 35.4±15.5 years, 18 men), from which 13 patients underwent early total reconstruction (etrTOF), while 16 patients were firstly palliated and later corrected (pcTOF). Their data were compared to that of 76 age- and gender-matched healthy controls (mean age: 35.9±7.6 years, 33 men). All repaired TOF patients and controls were assessed by two-dimensional (2D) Doppler echocardiography and 3DSTE.

Results

Dilated end-systolic and end-diastolic MA diameter, area and perimeter and reduced MA fractional area change and MA fractional shortening could be demonstrated in repaired TOF patients as compared to controls. Increased body surface area-indexed end-diastolic and end-systolic MA diameter and perimeter could be demonstrated in pcTOF patients as compared to that of etrTOF cases.

Conclusions

MA enlargement and functional impairment could be detected in adult patients with repaired TOF regardless of the type of correction. However, pcTOF patients have worse results.