Severe pulmonary regurgitation after tetralogy-of-Fallot repair: transcatheter treatment with the Edwards SAPIEN XT heart valve: Figure 1

Pre- and Postprocedure Imaging of Transcatheter Pulmonary Valve Implantation

Transcatheter pulmonary valve replacement (TPVR) is a minimally invasive procedure for treatment of right ventricular outflow tract (RVOT) dysfunction in surgically repaired congenital heart diseases. TPVR is performed in these patients to avoid the high risk and complexity of repeat surgeries. Several TPVR devices are now available to be placed in the right ventricle (RV) to pulmonary artery (PA) conduit, native RVOT, or surgical bioprosthetic valves. Imaging is used before TPVR to determine patient eligibility and optimal timing, which is critical to avoid irreversible RV dilatation and failure. Imaging is also required for evaluation of contraindications, particularly proximity of the RVOT to the left main coronary artery and its branches. Cross-sectional imaging provides details of the complex anatomy in which the TPVR device will be positioned and measurements of the RVOT, RV-PA conduit, or PA. Echocardiography is the first-line imaging modality for evaluation of the RVOT or conduit to determine the need for intervention, although its utility is limited by the complex RVOT morphology and altered anatomy after surgery. CT and MRI provide complementary information for TPVR, including patient eligibility, assessment of contraindications, and key measurements of the RVOT and PA, which are necessary for procedure planning. TPVR, performed using a cardiac catheterization procedure, includes a sizing step in which a balloon is expanded in the RVOT, which also allows assessment of the risk for extrinsic coronary artery compression. Follow-up imaging with CT and MRI is used for evaluation of postprocedure remodeling and valve function and to monitor complications. ^©RSNA, 2022 Online supplemental material is available for this article.

[Minimally invasive pulmonary valve replacement in pediatric patients: importance of imaging]

CLINICAL/METHODICAL ISSUE

Right ventricular outflow tract (RVOT) dysfunction with pulmonary regurgitation or obstruction is a common postsurgical consequence in congenital heart disease.

STANDARD RADIOLOGICAL METHODS

Magnetic resonance imaging (MRI) is widely accepted as standard method of imaging in congenital heart disease. It provides anatomical and functional information without radiation exposure and is therefore well suited for serial examinations.

METHODICAL INNOVATIONS

Percutaneous pulmonary valve implantation (PPVI) has been shown to be a safe and effective treatment option for patients with pulmonary valve insufficiency or stenosis. Correct patient selection for PPVI is crucial. It is important to be familiar with the indications and anatomical requirements for stent placement and to tailor imaging protocols.

PERFORMANCE

Imaging the RVOT, assessment of right ventricular volumes and function and calculation of pulmonary flow and regurgitation are core elements of the MRI examination prior to PPVI. Low interobserver and intraobserver variation allows even small changes to be detected.

ACHIEVEMENTS

Imaging provides relevant information for correct patient selection for PPVI and is part of postinterventional follow-up. Imaging is an important tool for documentation of success and for detection of complications.

PRACTICAL RECOMMENDATIONS

Several imaging modalities are used for evaluation of RVOTs; however, MRI can provide answers to most questions without radiation exposure.

Percutaneous pulmonary valve implantation

Pulmonary regurgitation (PR) is a frequent sequelae after repair of tetralogy of Fallot, pulmonary atresia, truncus arteriosus, Rastelli and Ross operation. Due to patient growth and conduit degeneration, these conduits have to be changed frequently due to regurgitation or stenosis. However, morbidity is significant in these repeated operations. To prolong conduit longevity, bare-metal stenting in the right ventricular outflow tract (RVOT) obstruction has been performed. Stenting the RVOT can reduce the right ventricular pressure and symptomatic improvement, but it causes PR with detrimental effects on the right ventricle function and risks of arrhythmia. Percutaneous pulmonary valve implantation has been shown to be a safe and effective treatment for patients with pulmonary valve insufficiency, or stenotic RVOTs.