Accuracy of Fetal Echocardiography in Defining Pulmonary Artery Anatomy and Source of Pulmonary Blood flow in Pulmonary Atresia with Ventricular Septal Defect (PA/VSD) Iman Naimi , Michele Clouse , Bhawna Arya , Jeffrey A Conwell, Mark B Lewin , Aarti H Bhat
PMID: 33683415; DOI: 10.1007/s00246-021-02579-0
Take Home Points:
- Fetal echocardiography accurately predicted central and branch pulmonary artery anatomy in 16 (89%) [confluent in 14, discontinuous in 2], patent ductus arteriosus status in 15 (83%) [present in 10, absent in 5], and major aorto-pulmonary collateral arteries in 17 (94%) [present in 9, absent in 8].
- Fetal echocardiography can provide accurate anatomical details in most fetuses with pulmonary atresia with ventricular septal defect. This allows for more anatomy–specific counseling, prognostication, and improved selection of postnatally available management options.
Commentary from Dr. Manoj Gupta (New York City, NY, USA), chief section editor of Pediatric & Fetal Cardiology Journal Watch
Precise delineation of central and branch pulmonary artery anatomy, patent ductus arteriosus, and major aorto-pulmonary collateral artery anatomy in the fetal diagnosis of pulmonary atresia with ventricular septal defect is challenging but important to prenatal counseling and postnatal management. In a subset of fetuses in whom a PDA is definitively ruled out and MAPCAs are identified as the sole source of pulmonary blood flow, the reflexive initiation of PGE and its attendant complications may be avoided if there is strong diagnostic confidence in fetal echocardiography.
Material and Methods:
On the fECHO, In general, an arterial structure was labeled as PA if it coursed from the mid-anterior part of the heart towards the hilum in a typical PA course. Arterial structures arising from underside of the aortic arch and coursing towards the central PA without bifurcation were labeled as PDA, while vessels arising more distally from the aortic arch and/or branching as they coursed towards the hilum were considered MAPCAs. Additional characteristics such as tortuosity, crossing the midline or a pronounced horizontal course were suggestive but not confirmatory of a MAPCA. If no clear identification was possible, vessel identity was noted as indeterminate. PAs were labeled as discontinuous if the branch PAs did not have any central connection to each other and each side had a separate source of blood flow.
Accuracy of Fetal Echocardiography
fECHO accurately predicted PA anatomy in 16 cases (89%) (confluent in 14, discontinuous in 2), and was unclear with regards to PA continuity in the remaining 2 cases. In one of these, ECHO reported discontinuous PAs but CTA demonstrated confluence. Postnatal ECHO confirmed presence of confluent branch PAs in 16 and discontinuous PAs in 2. PDA status was accurately predicted in 15 (83%) (present in 10, absent in 5). Two fetuses were predicted to have PDA but confirmed by postnatal imaging to have MAPCAs. In one of these patients the anatomy was not clear on postnatal ECHO and CTA was utilized to confirm the diagnosis. In one fetus, a prenatally predicted MAPCA was postnatally determined to be a PDA. Postnatal ECHO confirmed the presence of a PDA in 11 and absence in 7 patients. fECHO accurately predicted MAPCA status in 17 (94%) (present in 9, absent in 8). One patient with unclear prenatal PDA versus MAPCA was shown to have a PDA on postnatal ECHO as well as by direct visualization in the operating room. MAPCAs were postnatally confirmed to be present in 9 and absent in 9.
The classification of PA/VSD, also referred to as “complex pulmonary atresia”, is challenging due to its wide range of combinations of branch pulmonary artery anatomy and source of PBF. There is limited literature on accuracy of fECHO in delineating pulmonary artery anatomy and blood supply in PA/VSD. The main PA may be present or absent and the branch PAs, confluent or discontinuous, of normal size or variably hypoplastic and even absent. In 15–20% of patients, the lung segments are supplied exclusively by MAPCAs.
Surgical Repair and Re‑Intervention
In patients with PA/VSD and MAPCAs, unifocalization is the commonest surgical strategy. Earlier repair is associated with better outcomes. Patients with adequately sized and confluent native branch PAs tend to have better outcomes, while patients with discontinuous, diminutive branch PAs or lung segments supplied by MAPCAs are at higher risk for re-interventions and carry overall higher morbidity and mortality risk. Prospective studies have demonstrated significantly worse outcome in the group with MAPCAs as compared to those with PDAs with survival rates of 22% and 77%, respectively. Hence, prenatal determination of non-confluent and diminutive branch PAs or those predominantly supplied by MAPCAs represents worse outcome and families should be counseled accordingly
Using fECHO to delineate PA anatomy is challenging. ECHO has its own limitations as a definitive imaging modality for PA anatomy, particularly when the vessels are diminutive and supplied variably.
Our experience demonstrates a high degree of accuracy in delineating central PA anatomy and source(s) of PBF in PA/ VSD by fECHO. This allows for reliable and patient-specific prenatal counseling in predicting postnatal management, especially in an era where options such as PDA stenting or transcatheter perforation and balloon angioplasty of pulmonary valves have become more readily available across institutions.