Conotruncal Cardiac Defects: Recognition on Fetal Ultrasound Dennis Steed, MD ociate Professor artment of Pediatrics ision of Pediatric Cardiology t Carolina University – Brody School of Medicine enville, NC
Dec 17, 2015
Conotruncal Cardiac Defects:
Recognition on Fetal Ultrasound
R. Dennis Steed, MDAssociate ProfessorDepartment of PediatricsDivision of Pediatric CardiologyEast Carolina University – Brody School of MedicineGreenville, NC
Conotruncal Cardiac Defect:
A cardiac defect occurring early in development, involving faulty septation or connection of heart’s chambers and/or the major blood vessels leaving the heart.
The 4 Most Common Conotruncal Defects: frequency ( per 100,000 live births)
Tetralogy of Fallot 38
Transposition of the Great Arteries 25
Double Outlet Right Ventricle 11
Truncus Arteriosus 6
The 4 features typical of tetralogy of Fallot include:
1. Right ventricular (RV) outflow tract obstruction (RVOTO) (infundibular and valvar)
2. A large ventricular septal defect (VSD)
3. Aortic dextroposition resulting in aortic override of the VSD
4. Right ventricular hypertrophy
Tetralogy of Fallot:
1. The main pulmonary artery will be smaller than the aorta.
2. Large outlet VSD.
3. The overriding relationship of the aorta to the VSD.
Tetralogy of Fallot:Diagnostic features on fetal ultrasound
1. The great arteries are relatively parallel as compared to near perpendicular relationship in a normal heart.
2. Continuity of the anterior mitral leaflet with the posterior wall of the pulmonary artery.
3. The more anterior position of the aorta within the chest results in a rather elongated appearance of the aortic arch.
Transposition of the Great Arteries: Diagnostic features on fetal ultrasound:
1. The first branch off the MPA courses directly to the right ( right pulmonary artery)
2. The first branch off the aorta courses superiorly (innominate artery)
3. The MPA is considerably shorter than the ascending aorta, ie. The distance from the pulmonary valve to the right pulmonary artery is considerably shorter than the distance from the aortic valve to the innominate artery.
Distinguishing features between the Aorta and the Main Pulmonary Artery:
1. Both great arteries arise wholly or predominantly from the morphologic right ventricle.
2. Multiple anatomic variants based on:
a. The relationship of the great arteries (normally related or transposed.)
b. The relationship of the VSD to the great arteries ( A large subarterial VSD is almost always present).
Double Outlet Right Ventricle:
Diagnostic features on fetal ultrasound:1. Both great arteries arise predominantly from the
morphologic right ventricle.
2. There is infundibular muscle separating the anterior mitral leaflet from the artery which the artery which is anatomically closest to the left ventricle.
3. A large sub-arterial VSD is present in the vast majority of cases.
Double Outlet Right Ventricle:
A single arterial trunk arises from the ventricles with a single semilunar valve and typically overides a large VSD.
Truncus Arteriosus: