ABC | Volume 112, Nº5, May 2019

Guideline Brazilian Fetal Cardiology Guidelines – 2019 Arq Bras Cardiol. 2019; 112(5):600-648 20-G needle. 194 Removal of 1–2 ml of blood from the pericardium is usually enough to treat the condition. In most cases, this does not cause fetal anemia. These procedures are not exempt from risks involving the mother and/or the fetus. Maternal risks are currently extremely low and minimized, thanks to the increased experience in fetal surgery for noncardiac diseases. These complications include premature rupture of membranes, infection, hemorrhage, placental abruption, preterm labor, anemia, bradycardia, and fetal death. 202 There are still some doubts regarding the ideal moment to perform fetal cardiac intervention. Due to the reduced number of candidates and the morphological variability that every pathology may present, it is difficult to establish when it should be considered too late for intervention. 203 It seems reasonable to perform intervention as early as possible, soon after the diagnosis. From the technical point of view, however, it is very difficult to act before gestational week 20, due to the small dimensions of the fetal heart. Interventions performed very early may result in orifice and valve closure before the fetus has reached term. 203 On the other hand, late interventions do not prevent ventricular hypoplasia or avoid vascular damage of the pulmonary circulation. It appears to be consensual that the adequate period would be between gestational weeks 22 and 30. 190 8.3. Aortic Valvuloplasty The goal of aortic valvuloplasty is to change the natural history of critical aortic stenosis, maintaining left ventricular size and function adequate for biventricular physiology at birth or after a rehabilitation process. Alleviating left ventricular outflow obstruction reduces the left ventricular myocardial damage, thus facilitating Table 8.2 – Criteria for technical success (initial criteria) and criteria that indicate potential outcome to postnatal biventricular correction (modified criteria) Initial criteria (all of which must be present) Modified criteria* LV long-axis Z-score > −2 Aortic stenosis or atresia (mandatory) LV dysfunction capable of generating ≥ 10 mmHg pressure gradient across aortic valve or ≥ 15 mmHg mitral regurgitation jet gradient LV long-axis Z-score > −2 (mandatory) Mitral annulus Z-score > −3 Meet, at least, 4 of the following 5 parameters: • LV long-axis Z-score > 0; • LV short-axis Z-score > 0; • Aortic annulus Z-score > −3,5; • Mitral annulus Z-score > −2; • Aortic valve systolic gradient and/or LV-LA mitral regurgitation ≥ 20 mmHg LA: left atrium; LV: left ventricle. * Source: adapted from McElhinney et al. 195 chamber growth and myocardial function improvement. This hypothesis is based on animal models studies, which demonstrated the impact of load and flow conditions abnormalities on the developing myocardium, which leads to abnormal cardiovascular growth and function conditions. 204-209 According to the study published by McElhinney et al., 195 there are anatomical and functional characteristics that are predictive of technical success and progression to postnatal biventricular circulation, based on the experience of 70 fetal aortic valvuloplasty procedures performed by their group. 8 These criteria are shown in Table 8.2. There is evidence that the transition from normal left ventricle to HLHS in fetuses with critical aortic stenosis almost always occurs during the second or third trimester of gestation. 210 An interesting aspect observed by the authors is that the progressive growth of left structures during fetal life and early infancy may eventually result in biventricular correction during the first year of life. Applying the strategy initiated with fetal aortic valvuloplasty, treatment continues with neonatal hybrid procedure, which may or may not be associated with a new aortic valvuloplasty or Norwood procedure, with the maintenance of partially restrictive foramen ovale and aortic commissurotomy. This management is a bridge to biventricular correction following the process known as left ventricular rehabilitation. 189,201,211,212 Although diastolic dysfunction may be a problem in this group of patients, it is believed that this is better than the morbidity and mortality inherent in medium- and long- term of the univentricular pathways. 213 8.4. Critical Aortic Stenosis with Giant Left Atrium This is a very particular and severe presentation of critical aortic stenosis. In addition to obstructed left 638