Tetralogy of Fallot: Everything you wanted to know but were afraid to ask

Tetralogy of Fallot: Hypoxia, the villain of the story?

BACKGROUND

Tetralogy of Fallot (ToF) is a cyanotic congenital heart disease, composed of four malformations: persistent communication between the right and the left ventricle, pulmonary stenosis, overriding aorta, and right ventricle hypertrophy. The etiology of this disease is not entirely known as yet, but it has been proposed that the pathology has genetic components. During embryonic development, the fetus is exposed to a physiological hypoxia to facilitate the formation of blood vessels and blood cells through de novo processes.

METHODS

After researching scientific databases on the implications of oxygen on the normal and abnormal development of organs, especially the heart, we were able to propose that oxygen deprivation may be the cause of the disease.

RESULTS

During this period, the hypoxia-inducible factor is activated and triggers transcriptional responses that enable adaptation to the hypoxic environment through angiogenic activation. High levels of this protein can alter certain physiological pathways, such as those related to the vascular endothelial growth factor. Research has shown that prolonged oxygen deprivation during embryological development can lead to the occurrence of congenital heart diseases, such as ToF.

CONCLUSIONS

Studies using animal models have demonstrated that the deficiency or disruption of a protein called "CITED2," which plays an important role in cardiac morphogenesis and its loss, results in the alteration of pluripotent, cardiac, and neural lineage differentiation, thereby disrupting the normal development of the heart and other tissues.

Effect of hemoglobin and oxygen saturation on adverse outcomes in children with tetralogy of fallot: a retrospective observational study

BACKGROUND

Tetralogy of Fallot (TOF) is a common cyanotic congenital heart malformation that carries a high risk of right-to-left shunting. Anemia is characterized by decreased hemoglobin (Hb) levels that can affect tissue oxygen delivery and impact postoperative recovery in patients. Chronic hypoxia caused by right-to-left shunting of TOF could lead to compensatory increases in Hb to maintain systemic oxygen balance. This study aims to investigate whether preoperative Hb and blood oxygen saturation (SpO2) can predict adverse outcomes in children undergoing corrective surgery for TOF.

METHODS

This retrospective study included patients under 18 years of age who underwent corrective surgery for TOF at Fuwai Hospital between January 2016 and December 2018. Adverse outcomes, including in-hospital death, extracorporeal membrane oxygenation implantation, ICU stay > 30 days, and severe complications, were considered as the primary outcome. Univariable and multivariable logistic analyses were performed to identify independent risk factors for adverse outcomes. Propensity score-matched (PSM) analysis was also conducted to minimize the confounding factors.

RESULTS

A total of 596 children were included in the study, of which 64 (10.7%) experienced adverse outcomes. Hb*SpO2 < aaHb was identified as an independent risk factor for adverse outcomes (OR = 2.241, 95% CI = 1.276-3.934, P = 0.005) after univariable and multivariable logistic analyses. PSM analysis further confirmed the association between Hb*SpO2 < aaHb and adverse outcomes. Patients with Hb*SpO2 < aaHb had a significantly higher incidence of postoperative adverse outcomes, longer time of mechanical ventilation, and hospital stay, as well as higher in-hospital costs.

CONCLUSIONS

Hb*SpO2 < aaHb is significantly associated with adverse outcomes in children undergoing corrective surgery for TOF. Clinicians can use this parameter to early identify high-risk children and optimize their postoperative management.

Outcomes of Surgical Repair of Tetralogy of Fallot: A Comparison Between the Adult and Pediatric Population

Introduction Tetralogy of Fallot (TOF) is the most common cyanotic congenital heart disease. Early detection and timely treatment have provided successful repair of the anomaly in the developed world. However, in the developing world, there is still a burden of uncorrected TOF patients reaching adulthood. The goal of this study is to determine whether there is any difference in postoperative complications between adult and pediatric populations following surgical correction for TOF. Methods This study involved all those patients who received primary or secondary surgical repair for TOF in our facility between January 2017 and December 2020. The patients were split according to their age into the pediatric group if they were under 18 years and the adult group if they were 18 years or older. Patients with absent pulmonary valve or pulmonary atresia were not included in this study. Patients with large major aortopulmonary collateral arteries (MAPCA) were also excluded from this study. All patients underwent total correction through a median sternotomy approach. The ventricular septal defect was closed with a Bard knitted fiber patch. The right ventricular outflow tract (RVOT) was augmented by excising muscle bands or fibrous bands in the RVOT. If the annulus was smaller than the 3.5 z score, then a transannular patch was done using an autologous pericardium. The main pulmonary artery was augmented in every surgery using an autologous pericardial patch. All patients were shifted to the ICU on the ventilator and were extubated after fulfillment of the extubation criteria. Postoperative complications measured included re-opening, re-intubation, prolonged ventilation (>24 hours), and mortality within the index hospital admission. The clinical data of all patients were prospectively collected and analyzed using the chi-square test and t-test. A p-value of less than or equal to 0.05 was considered significant. Results The total number of patients was 134. This included 83 males (60.1%). A total of 114 patients who were aged below 18 years were included in the pediatric group, and 20 patients aged equal to or more than 18 years were included in the adult group. The mean average perfusion time in minutes in the adult group was 125.8 and in the pediatric group, it was 98.79. Similarly, the mean average of the cross-clamp time was also longer in the adult group at 89.55 minutes versus 69.63 minutes in the pediatric group. Overall, in the adult group, three (15%) patients had postoperative complications, while in the pediatric group, a total of 14 (11.9%) patients had postoperative complications (p = 0.001). However, there was no significant difference in the number of re-openings (8.5% vs. 10%; p = 0.8). The total mortality observed was 16 (11.59%). This included 14 (11.9%) in the pediatric group and two (10%) in the adult group. There was no significant difference between the two groups (p = 0.8). Conclusions Surgical repair of TOF can be performed in both adult and pediatric populations with acceptable outcomes. The mortality rate was found to be slightly greater in the pediatric population compared to the adults. However, it can be seen that the number of postoperative complications is greater in adults. Further research is needed to optimize outcomes for both pediatric and adult patients with TOF.

Tetralogy of Fallot Presenting with Superior Vena Cava Syndrome - A Rare Presentation

Tetralogy of Fallot (TOF) presenting with superior vena cava (SVC) syndrome is an exceedingly rare scenario. The diagnosis of this condition is still a difficult task due to its unspecific clinical features and unclear recommendations for the best diagnostic tools. We report an interesting case of a 23-year-old male who was found to have TOF with the presentation of SVC syndrome after a sequential diagnosis. The timely diagnosis helped in the successful management of the patient. Through this case, we want to make clinicians aware of such a rare association and its diagnosis.

Routine Perioperative Esmolol After Infant Tetralogy of Fallot Repair: Single-Center Retrospective Study of Hemodynamics

OBJECTIVES

Currently, surgical repair of tetralogy of Fallot (TOF) is associated with an 1.1% 30-day mortality rate. Those with junctional ectopic tachycardia (JET) and restrictive right ventricular physiology have poorer outcomes. Routine postoperative adrenergic or inodilator therapy has been reported, while beta-blockade following cardiopulmonary bypass has not. This study evaluated routine perioperative treatment with esmolol in infants undergoing TOF repair.

DESIGN

Retrospective chart review of the perioperative course following TOF repair.

SETTING

Single-center case series describing perioperative management of TOF in a cardiac ICU.

PATIENTS

This study reviewed all patients less than 18 months old who underwent TOF repair, excluding cases of TOF with absent pulmonary valve or atrioventricular septal defect, at our institution from June 2018 to April 2021.

INTERVENTIONS

This review investigates the hemodynamic effects of esmolol following cardiopulmonary bypass for TOF repair.

MEASUREMENTS AND MAIN RESULTS

Preoperative clinical characteristics and perioperative course were extracted from the medical record. Descriptive statistics were used. Twenty-six patients receiving perioperative esmolol after TOF repair were identified and included. Postoperative hemodynamic parameters were within a narrow range with minimal vasoactive support in most patients. Three of 26 patients experienced JET, and one of 26 of whom had a brief cardiac arrest. Median and interquartile range (IQR) for hospital and postoperative length of stay was 7 days (IQR, 6-9 d) and 6 days (IQR, 5-8 d), respectively. There were no 30-day or 1-year mortalities.

CONCLUSIONS

In this infant cohort, our experience is that the routine use of postoperative esmolol is associated with good cardiac output with minimal requirement for vasoactive support in most patients. We believe optimal postoperative management of infant TOF repair requires a meticulous multidisciplinary approach, which in our experience is enhanced with routine postoperative esmolol treatment.

Physiologic function of mediastinum space

The mediastinum forms the central part of the thoracic cavity that is surrounded by pleural space on the two sides, thoracic vertebrae at the posterior, thoracic inlet on the top, and diaphragm at the bottom. It encompasses cardiopulmonary organs and organ systems. Pathological dysfunction or deformity in any part of the mediastinum can have adverse cardiovascular and respqiratory effects. Pectus excavatum and pectus carinatum are the most common congenital chest deformities that are characterized by sternal depression and protuberance of the sternum, respectively. Together, these account for 90% of chest wall deformities. Patients are known to be represented with respiratory distress and cardiovascular dysfunction. The aim of the review article is to present the anatomical and physiological role of the mediastinum in association with important parts of the thoracic cavity and pathological dysfunction of the mediastinum (cardiopulmonary system) due to pectus excavatum and pectus carinatum.

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Mediastinum forms the central part of thoracic cavity that is surrounded by pleural space.

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PC and PE are structural chest deformities.

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Chest deformation by pressing on the chin causes coughing, stridor, dyspnea and exacerbation.

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Clinical symptoms along with inflammation that requires urgent medical treatment.

Identification of a De Novo LRP1 mutation in a Saudi Family with Tetralogy of Fallot

BACKGROUND

Tetralogy of Fallot (TOF) is a rare, complex congenital heart defect caused by genetic and environmental interactions that results in abnormal heart development during the early stages of pregnancy. Genetic basis of TOF in Saudi populations is not yet studied. Therefore, the objective of this study is to screen for the molecular defects causing TOF in Saudi patients.

METHODS

A family with non-syndromic TOF was recruited from the Western region of Saudi Arabia. Whole exome sequencing (WES) was performed on the proband and her parents. The identified candidate variant was verified by sanger sequencing. Also, different computational biology tools were used to figure out how candidate variants affect the structure and function of candidate protein involved in TOF.

RESULTS

A novel heterozygous de novo mutation in LRP1 (p. G3311D) gene was identified in the index case. Also, this variant was absent in the in-house exome sequencing data of 80 healthy Saudi individuals. This variant was predicted to be likely pathogenic, as it negatively affects the biophysical chemical properties and stability of the protein. Furthermore, functional biology data from knock out mouse models confirms that molecular defects in LRP1 gene leads to cardiac defects and lethality. This variant was not previously reported in both Arab and global population genetic databases.

CONCLUSION

The findings in this study postulate that the LRP1 variant has a role in TOF pathogenesis and facilitate accurate diagnosis as well as the understanding of underlying molecular mechanisms and pathophysiology of the disease.

Detection of Coronary Artery and Aortic Arch Anomalies in Patients with Tetralogy of Fallot Using CT Angiography

Background: Tetralogy of Fallot (TOF) is the most common form of cyanotic congenital heart disease (CHD). Furthermore, the prevalence of anomalous origin of a coronary artery is higher in patients with TOF than in the general population (6% vs. ≤1%). Preoperative assessment of cardiovascular anatomy using computed tomography (CT) angiography enables the adaptation of the surgical approach to avoid potentially overlooked anomalies. Our purpose was to determine the prevalence of coronary artery and aortic arch anomalies in a cohort of TOF patients. Methods: In this retrospective analysis, data were collected from CT reports (2015–2021) of 105 TOF patients. All images were acquired using a 64-slice multi-detector CT (MDCT) scanner. Results: The median age of the patients was 38.7 months, with a male-to-female ratio of 1.39. The overall prevalence of coronary artery anomalies (CAAs) was 7.61% (8 of 105 cases). The anomalous origin and course of coronary arteries across the right ventricular outflow tract (RVOT; prepulmonic course) were defined in 5.71% of cases (six patients). In four of these, the left anterior descending artery (LAD) originated from the right coronary artery (RCA), while in two cases, the RCA arose from the LAD. In the remaining two patients, the coronary arteries followed an interarterial course. The most frequent anomalous aortic arch pattern in the overall TOF population was the right aortic arch (RAA) with mirror image branching, seen in 20% of patients (21 cases). The most frequent anomaly of the supra-aortic trunks was bovine configuration, found in 17.14% (18 cases). Conclusions: The prevalence of CAAs and aortic arch anomalies detected by CT angiography was in line with the data reported in anatomical specimens. Therefore, this technique represents a powerful tool for the evaluation of congenital cardiovascular anomalies.

[The adult with tetralogy of fallot: what the clinical cardiologist needs to know]

Tetralogy of Fallot (TOF) is the most common cyanotic congenital heart disease. After more than seven decades of the first palliative surgery, TOF prognosis has changed dramatically. The prevalence of TOF is approximately 3 per 10 000 births, representing 7 to 10% of congenital heart disease. With a higher survival into adulthood, the clinical cardiologist faces challenges in the management of this population, from severe pulmonary regurgitation to heart failure and ventricular arrhythmias. Its prevalence is approximately 3 per 10 000 live births, representing 7 to 10% of congenital heart disease. This review will describe the most relevant aspects of the care of adult patients with this disease.

Congenitally Corrected Transposition of Great Arteries with Dextrocardia, Patent Ductus Arteriosus, Atrial Septal Defects and Ventricular Septal Defects in a 15-Year-Old Marfanoid Habitus Patient: A Case Study

Congenitally corrected transposition of the great arteries (CCTGA) is a rare congenital cardiac anomaly defined by atrio-ventricular and ventriculo-arterial discordance. This malformation makes up less than 1% of congenital heart defects. We report here a case of a 15-year-old female who presented to our hospital with dyspnea as seen in the New York Heart Association (NYHA) Functional Classification class III and hemoptysis. She was clinically found to have marfanoid habitus, and subsequent echocardiographic study disclosed CCTGA-associated with Ebstein's anomaly, ventricular septal defect, left ventricular outflow obstruction, right ventricular outflow obstruction, co-existing dextrocardia, atrial septal defect, patent ductus arteriosus, non-confluent pulmonary arteries, and pulmonary atresia. This case highlights the association between such rare cardiac conditions. To the best of our knowledge, this is the first case of CCTGA at a young age, with the aforementioned abnormalities documented in the literature reported from Pakistan.

Clinical and postmortem findings of pentalogy of Fallot in an 18-month-old Holstein heifer

An 18-month-old female Holstein Friesian heifer presented with a history of stunted growth and a recent onset of anorexia; she presented with cyanosis and eventually died. A postmortem examination revealed obstruction of the right ventricular outflow tract, ventricular septal defect, overriding aortic root, right ventricular hypertrophy, and an atrial septal defect, indicating a pentalogy of Fallot (POF). In addition to POF, the heifer also had pulmonary artery dilatation, although she did not present with patent ductus arteriosus. This heifer had the longest lifespan among the Holstein cattle reported to have POF, which may be secondary to delayed pulmonary obstruction due to deformation of one of the pulmonary valves.