Tetralogy of Fallot and Minimally Invasive Cardiac Surgery
1. What Is Tetralogy of Fallot?
Tetralogy of Fallot accounts for 5–10% of congenital heart defects and is the most common cyanotic congenital heart disease [6].
Morphologically, Tetralogy of Fallot comprises four congenital anomalies: a large ventricular septal defect (VSD), right ventricular outflow tract (RVOT) obstruction, right ventricular hypertrophy, and an overriding aorta.
Hemodynamically: Due to RVOT obstruction, unoxygenated blood cannot reach the lungs for oxygen exchange into oxygenated blood as normal; instead, this blood shunts across the ventricular septal defect into the aorta, causing cyanosis in the child. The degree of cyanosis and clinical severity depend on the size of the ventricular septal defect and the severity of the right ventricular outflow tract obstruction [7].
Symptoms and signs range from non-cyanotic heart failure to severe cyanosis accompanied by hypoxia and acidosis.
The diagnosis of Tetralogy of Fallot is primarily based on echocardiography. In addition, echocardiography is used to evaluate coronary artery anomalies and other associated congenital defects, such as patent ductus arteriosus, pulmonary valve anomalies, the pulmonary trunk and branches, and associated atrioventricular septal defects, among others.
2. Management of Tetralogy of Fallot
For simple Tetralogy of Fallot where right ventricular outflow tract obstruction is not excessively severe, surgical intervention may not be required early in the neonatal period due to higher surgical risks. The condition can be medically stabilized using Propranolol, iron supplementation, etc. In some cases, balloon dilation of the right ventricular outflow tract or temporary pulmonary valvuloplasty can be performed prior to complete surgical repair later.
For Tetralogy of Fallot with severe right ventricular outflow tract obstruction, frequently accompanied by pulmonary valve hypoplasia, pulmonary artery hypoplasia, etc., infants present with marked cyanosis immediately after birth and will undergo immediate intervention to ameliorate hypoxemia and cyanosis via medical measures such as oxygen therapy and Prostaglandin administration to maintain ductal-dependent pulmonary blood flow.
Following neonatal stabilization, physicians will counsel families regarding temporary procedures or palliative surgeries—such as patent ductus arteriosus stenting, right ventricular outflow tract stenting, or palliative systemic-to-pulmonary shunts (modified BT shunt, Melbourne shunt, etc.)—to improve arterial oxygenation. Ultimately, the physician advises relatives on the appropriate timing and technique for complete surgical repair tailored to each individual patient. Complete repair is typically performed around 3 to 12 months of age [6].
3. Minimally Invasive Total Repair of Tetralogy of Fallot
Globally, congenital heart defects such as atrial septal defects, ventricular septal defects, partial anomalous pulmonary venous return, and partial atrioventricular septal defects are increasingly performed via minimally invasive approaches [4], predominantly through a right mini-thoracotomy or right-sided chest incisions rather than a median sternotomy.
The objective of Tetralogy of Fallot repair is to provide the child with the most anatomically normal heart possible, minimizing the rate of reoperation and re-intervention that could adversely affect the child's quality of life. Common postoperative complications include severe pulmonary regurgitation, residual pulmonary stenosis, pulmonary branch stenosis, tricuspid regurgitation, and residual ventricular septal defects. Undergoing a minimally invasive primary procedure only to experience complications necessitating re-intervention or reoperation is undesirable. Globally, few studies report total repair of Tetralogy of Fallot via minimally invasive approaches, likely due to a potentially higher intraoperative and postoperative complication rate [5]. Therefore, patient selection for minimally invasive complete repair of Tetralogy of Fallot is critically important.
Currently, University Medical Center Ho Chi Minh City is initiating patient selection and performing minimally invasive complete repair of simple Tetralogy of Fallot. This represents a significant milestone following the Pediatric Cardiac Surgery Department's successful execution of atrial septal defect closure, ventricular septal defect closure, partial atrioventricular septal defect repair, and partial anomalous pulmonary venous return repair via minimally invasive surgical approaches.
4. References
- [1] https://www.mayoclinic.org/diseases-conditions/tetralogy-of-fallot/symptoms-causes/syc-20353477
- [2] https://my.clevelandclinic.org/health/diseases/22343-tetralogy-of-fallot
- [3] https://ctsnet.figshare.com/articles/media/Minimally_Invasive_ToF_Repair_in_2_Month_Old_Child/14511972
- [4] https://www.sciencedirect.com/science/article/abs/pii/S0003497523012481
- [5] https://www.medrxiv.org/content/10.1101/2022.12.05.22283045v1
- [6] Park Myung K., Salamat Mehrdad (2021), “Tetralogy of Fallot”, Park’s Pediatric Cardiology for Practitioners, 7th, Elsevier, 176-181.
- [7] Abraham Rudolph (2009), “Pulmonary stenosis and atresia with ventricular septal defect (tetralogy of Fallot)” Congenital Diseases of the Heart Clinical-physiological considerations, chapter 14, 3rd, Wiley-Blackwell, 345-385
The information above is for reference purposes only and is not intended as medical advice. Please contact your doctor for detailed medical consultation.