New Delhi: Tetralogy of Fallot (TOF) is the most common cyanotic congenital heart defect. This comprises a large malaligned VSD with aortic overriding with severe subvalvular pulmonary stenosis and associated right ventricular hypertrophy. To know all about TOF interview Dr Supratim Sen, Senior Consultant Pediatric Cardiologist, Narayana SRCC. The expert answered all questions about the condition, its effects on newborns, treatment options, and more.
Can it be diagnosed during pregnancy?
TOF can be diagnosed with fetal echo and can be detected as early as 16-18 weeks gestation. In all fetal echo diagnoses of TOF, we need to delineate the antegrade pulmonary blood flow of the pulmonary stenosis and differentiate this from pulmonary atresia. In pulmonary atresia, there is no connection between the right ventricle and the pulmonary artery, and the pulmonary arteries are supplied by either a PDA or by major aortopulmonary collateral arteries (MAPCAs). Thus, TOF with pulmonary atresia is a duct-dependent condition that will require delivery in a cardiac center and may require a neonatal intervention or surgery.
What advice do we give to patients if TOF is diagnosed during pregnancy?
TOF generally has a good long-term prognosis, and we tell the parents about the treatment options available. The long-term outcomes often depend on the size of the branch pulmonary arteries. Pulmonary atresia is a more complex disease and will require multiple surgeries in the lifetime of the patient.
After birth, what symptoms does a patient with TOF have?
Most babies born with TOF may have mild desaturation at birth. Generally, in TOF with adequate antegrade pulmonary blood flow, if the SpO2 is above 80% and the baby has no respiratory distress, no neonatal intervention is required.
What are cyanotic spells? How are these managed?
Older children with TOF, usually above the age of 2-6 months, have a baseline cyanosis, and episodic worsening of the cyanosis on crying. The worsening cyanosis can lead to hypoxia, and if it does not resolve spontaneously or with treatment, this may progress to hypoxic seizures and stroke. These episodes are known as cyanotic spells. The first step in the treatment of cyanotic spells is to calm the baby and to put the baby in a knee-chest position. Other measures, which can be done at any local pediatric hospital include oxygen by facemask, normal saline bolus, and slow intravenous bicarbonate injection along with sedation with intravenous morphine. Intravenous Metoprolol also helps in the treatment of cyanotic spells. Frequent or refractory cyanotic spells need to be treated by intubation and ventilation, followed by early cardiac surgery.
If the baby with TOF has low oxygen levels, how do we treat the baby?
If the saturations of the baby are < 75%, the first step is to add oral propranolol. If there is no improvement in propranolol, or if the child continues to have frequent cyanotic spells, we will then need to plan for an early interventional or surgical palliation or early corrective surgery.
Early interventional options for TOF include balloon pulmonary valvotomy or right ventricular outflow tract stenting. If there is a small PDA in TOF, another good palliative option is PDA stenting.
RVOT stenting: The surgical palliative treatment option is a modified BT shunt, where a small connection is made between one of the subclavian arteries and the ipsilateral branch pulmonary artery.
At what age do we plan for complete surgical correction in these patients?
Studies have shown that the best outcomes of total surgical correction of TOF are seen if the child is operated on between 3 months to 9 months of age. In India, we offer elective surgery to all stable patients with TOF from 5-6 months of age, but it is not uncommon for us to see late presenters who are diagnosed after 1 year of age. These patients are operated on soon after diagnosis. Of late, at our center, we have started offering early Total correction of TOF even to babies as young as 3-4 weeks of age, if the cyanosis is significant, and the branch PA anatomy is otherwise good. Syndromic child with multiple congenital anomalies or those with small hypoplastic branch pulmonary arteries are often offered palliative surgery as the first step, with total correction planned 6 months to 1 year later.
Is it a single surgery for TOF patients, or do they need more than one surgery in their lifetime?
Children who undergo total correction of TOF with preservation of the pulmonary annulus require only a single surgery. In some patients, the pulmonary annulus is extremely hypoplastic and needs to be enlarged with a transannular incision and patch during the surgery. In these patients, there will be severe pulmonary regurgitation after TOF surgery, and they will require a pulmonary valve replacement to achieve pulmonary valve competence and prevent severe right ventricular dilation around 10 to 15 years after the TOF surgery.
Are any minimally invasive options available for the treatment of these patients who require a pulmonary valve replacement later in life?
Over the last decade, transcatheter pulmonary valve replacement in the cardiac cath lab has become a regular treatment option for patients who require a pulmonary valve replacement. We now have various options for transcatheter pulmonary valve implantation, and although this is still more expensive than surgery, it is slowly becoming a viable treatment alternative.
What is the long-term outcome of these patients?
Patients operated for Tetralogy of Fallot will usually have a normal quality of life into adulthood, and pregnancy is safe in operated female TOF patients. They have normal exercise tolerance and excellent long-term outcomes. In patients with TOF with pulmonary atresia, outcomes are variable and depend on the sizes of the branch pulmonary arteries at birth. Those patients with non-confluent small branch pulmonary arteries can be offered multiple staged surgeries, but their long-term outcomes are not very good.
Most babies born with TOF may have mild desaturation at birth. Generally, in TOF with adequate antegrade pulmonary blood flow, if the SpO2 is above 80% and the baby has no respiratory distress, no neonatal intervention is required. Health News Health News: Latest News from Health Care, Mental Health, Weight Loss, Disease, Nutrition, Healthcare
