The following are key points to remember from a state-of-the-art review on transcatheter-based interventions for tetralogy of Fallot (TOF) across all age groups:

1. TOF is the most common cyanotic congenital heart disease (CHD), occurring in 3–5 out of every 10,000 live births.
2. Initial treatment strategies for TOF can include palliative transcatheter or surgical interventions as well as primary surgical repairs.
3. In pediatric patients, transcatheter interventions can be performed after initial palliative or corrective surgery to treat residual lesions, or as palliation including patent arterial duct (PDA) stenting, right ventricular outflow tract (RVOT) stenting, or ballon pulmonary valvuloplasty.
4. Recent data suggest that palliative transcatheter interventions can be considered as an alternative to surgical palliation, particularly in low-birth-weight neonate in infants <3 months of age with clinically significant cyanosis or cyanotic spells and/or associated comorbidities.
5. Stenting of the PDA may be performed in infants with ductal-dependent pulmonary blood flow. Pre-procedural computed tomography (CT) imaging is useful in determining ductal anatomy, selecting appropriate stent size, and identifying sites for vascular access.
6. Complete coverage of the duct is crucial with ductal stenting. Jailing of the pulmonary arteries should be avoided, as it is associated with higher reintervention rates.
7. Pulmonary balloon valvuloplasty may be considered as a palliative procedure when there is obstruction primarily at the valve level, and minimal infundibular obstruction. It is associated with a high rate of reintervention.
8. Transcatheter RVOT stenting may be physiologically advantageous as compared with surgical shunts. Suitable candidates for RVOT stenting include infants with a high-risk profile for conventional surgical palliation or patients at low risk for surgical palliation but requiring short-term support to the pulmonary circulation due to anticipated early surgical repair.
9. Transcatheter pulmonary valve replacement may be considered for adults with tetralogy of Fallot and moderate or greater pulmonary valve regurgitation or pulmonary stenosis with symptoms or evidence of RV dilatation or dysfunction.
10. The Melody Valve (Medtronic, Inc.) is a balloon-expandable transcatheter pulmonary valve approved for use for patients with RVOT conduit dysfunction, for an existing dysfunctional bioprosthetic valve. Similarly, the SAPIEN XT and the SAPIEN S3 (Edwards Lifesciences) are approved for similar indications as the Melody Valve.
11. More recently, The Harmony Transcatheter Pulmonary Valve by Medtronic and the Alterra Adaptive Prestent system received FDA approval in 2021. These may be used for patients with large, dilated native RVOTs after transannular patch repairs or pulmonary valvotomy/valvectomy. CT scans are important in assessing candidacy for these valves.
12. The Alterra Adaptive Prestent is not an actual valve but is a size reducer and “landing zone” for a 29 mm SAPIEN S3 valve.
13. Ventricular arrhythmias are an important consideration post–stent valve implantation in patients with native RVOT. Extension of the stent into the RVOT may trigger ventricular arrhythmias. The stent itself can limit access to the RVOT myocardium. A comprehensive electrophysiologic assessment may be considered prior to valve implantation.
14. Long-term complications after transcatheter pulmonary valve implantation include stent fracture and endocarditis.

Clinical Topics: Congenital Heart Disease and Pediatric Cardiology, Congenital Heart Disease, Invasive Cardiovascular Angiography and Intervention

Keywords: Heart Defects, Congenital, Tetralogy of Fallot

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