ABC | Volume 112, Nº5, May 2019

Guideline Brazilian Fetal Cardiology Guidelines – 2019 Arq Bras Cardiol. 2019; 112(5):600-648 Table 2.2 – Heart diseases commonly associated with a normal four- chamber view Tetralogy of Fallot Transposition of the great arteries Common truncus arteriosus Anomalies of the aortic arch Mild aortic and pulmonary valve stenosis Perimembranous ventricular septal defect Table 2.3 – Heart diseases commonly associated with an abnormal four-chamber view Mitral and/or aortic atresia Tricuspid and/or pulmonary atresia Ebstein’s anomaly/tricuspid valve dysplasia Atrioventricular septal defects Large ventricular septal defects Single ventricles Severe aortic and pulmonary valve stenosis Coarctation of the aorta Total anomalous pulmonary venous return Cardiomyopathies Cardiac tumors In summary, the analysis of the four-chamber view should include the following reference points: • Spine. • Descending aorta in a transverse plane. • Left atrium close to the descending aorta and with the foramen ovale flap moving. • Right ventricle with the apex “filled in” by a piece of muscle called the moderator band. • Two atria of similar size. • Two ventricles of similar size, thickness and contractility (the right ventricle may be slightly larger). • The interatrial and interventricular septum join the atrioventricular valves in the middle of the heart, suggesting the image of a cross, the “crux cordis.” • The interventricular septum should be intact and make an angle of approximately 45º with the midline of the body. • Two atrioventricular valves with equal opening orifices. The insertion of the septal leaflet of the tricuspid valve is closer to the cardiac apex, resulting in a minimal difference in the level of implantation of the anterior leaflet of the mitral valve. Sometimes, this difference is quite subtle, resulting in great difficulties in excluding the diagnosis of atrioventricular septal defect and single AV valve junction. • The interatrial septum may be seen with the foramen ovale and its flap, tilting with the LA. • The pulmonary veins drainage in the left atrium should be identified in two-dimensional view and confirmed by colored Doppler or power Doppler. Failure to obtain a normal four chamber view during the obstetric ultrasound scan is an absolute indication for fetal echocardiogram. Because the four-chamber view does not include the examination of the right and left ventricular outflows, important diseases such as transposition of the great arteries, tetralogy of Fallot (TOF), common truncus arteriosus, among others may be missed. Tables 2.2 and 2.3 show the different heart diseases commonly associated with normal and abnormal four chamber views, respectively. 2.2.3. Step 3 – 3 rd Level: Left Ventricular Outflow Tract Starting from the four-chamber views, the left and right outflow tracts and respective arteries can be seen swiping the transducer toward the fetal head. The left ventricular outflow tract is the first identified in the middle of the heart and it directs toward the fetal right shoulder. In this view it is possible to observe the membranous continuity of the septum with the aorta, which rules out a possible overriding aorta or great artery commonly seen in tetralogy of Fallot, truncus arteriosus, and other complex anomalies. 2.2.4. Step 4 – 4 th Level: Right Ventricular Outflow Tract Swiping slightly the transducer up, the right ventricular outflow tract is reached. It is the most anterior structure of the heart and is exactly below the fetal sternum. It crosses aorta from right towards the left. The great arteries are symmetric at the beginning of gestation, but during the second and the third trimesters the pulmonary trunk is slightly larger than the aorta. 2.2.5. Step 5 – 5 th Level: Three Vessels View This is a special view that allows to analyze the spatial relationship of the pulmonary artery, the aorta and the superior vena cava (SVC). In this view the vessels are seen immediately after their ventricular origins. Important information should be obtained from the 606