Table 4.2.

Distribution of fetal heart diseases according to their classification

Group	Cardiac anomalies
IA	Left to right shunt heart diseases: ASD, VSD, AVSD, and Ao-P window Diseases with mild outflow tract obstructions: PS, AS, and CoA Complex congenital heart diseases without significant obstructions of systemic or pulmonary outflow tracts: TOF, complex TGA, DORV, univentricular hearts, and CTGA
IB	Isolated extrasystoles; mild, isolated TR
IIA	Heart diseases with critical obstruction of systemic or pulmonary outflow tracts: PAIVS, Critical PS, Critical AS, and HLHS Heart diseases that need interatrial shunt: HLHS and variations, TGA, and TA Heart diseases with severe valve insufficiencies: Ebsteins anomaly and tricuspid valve dysplasia, pulmonary valve agenesis, severe primary or secondary MR, secondary TR, and truncal valve insufficiency
IIB	Cardiomyopathies and myocarditis, arrhythmias, obstructive tumors, extrinsic compressions, (CDH and CCAM), ductal constriction, restrictive foramen ovale, ductus venosous agenesis, AVMs, TTTS, and twin gestation with 1 acardiac fetus
III	Severe chromosomal disorders; multiple malformations, cardiac defects that are not correctable, very severe forms of Ebsteins anomaly or tricuspid valve dysplasia with lungs hypoplasia, LV aneurysms, or diverticula associated with fetal hydrops

Ao-P: aortic to pulmonary; AS: aortic stenosis; ASD: atrial septal defect; AVMs: arteriovenous malformations; AVSD: atrioventricular septal defect; CCAM: congenital cystic adenomatoid malformation; CDH: congenital diaphragmatic hernia; CoA: coarctation of the aorta; CTGA: corrected transposition of great arteries; DORV: double outlet right ventricle; HLHS: hypoplastic left heart syndrome; LV: left ventricle; MR: mitral regurgitation; PAIVS: pulmonary atresia and intact ventricular septum; PS: pulmonary stenosis; TA: tricuspid atresia; TGA: transposition of great arteries; TOF: tetralogy of Fallot; TR: tricuspid regurgitation; TTTS: twin-twin transfusion syndrome; VSD: ventricular septal defect.