ABC | Volume 114, Nº5, May 2020

Statement Brazilian Cardiology Society Statement for Management of Pregnancy and Family Planning in Women with Heart Disease – 2020 Arq Bras Cardiol. 2020; 114(5):849-942 Table 6 – Radiation doses associated with radiological examinations Modality Fetal dose (mGy) Maternal dose (mSv) Breast dose (mGy) Tomography Pulmonary angiography 0.01 to 0.66 2.7 to 40 8 to 70 Abdomen and pelvis 13 to 25 3 to 45 – Angiography of thoracic and abdominal aorta, with or without contrast agent 6.7 to 56 4 to 68 16 to 130 Coronary artery angiography 0.1 to 3 7 to 39 10 to 90 Simple abdomen and pelvis computed tomography 10 to 11 3 to 10 – Nuclear medicine Low-dose perfusion scintigraphy 0.1 to 0.5 0.6 to 1.0 0.1 to 0.3 V/Q scintigraphy 0.1 to 0.8 1.2 to 2.8 0.2 to 0.7 Myocardial viability PET with 18 F-FDG 6.8 to 8.1 7 – Myocardial perfusion with 99m Tc-sestamibi 17 11.4 to 14.8 – Myocardial perfusion with 99m Tc-tetrofosmin 8.45 9.3 to 11.6 – Radiography Mammography, 2 positions 0.001 to 0.01 0.1 to 0.7 3 Thorax radiography, 2 positions 0.0005 to 0.01 0.06 to 0.29 < 0.4 Abdominal radiography 0.1 to 0.3 0.01 to 1.1 – FDG: fluorodeoxyglucose; PET: positron emission tomography; V/Q: ventilation/perfusion. Note: Estimated doses vary according to protocol, radiotracer, dosage, dose calculation method, and patient-dependent factors (e.g. body weight and tissue percentage of the mammary gland). V/Q scintigraphy and CTPA are efficacious for diagnosing pulmonary embolism during pregnancy, although CTPA demonstrates advantages for identifying other pulmonary diseases. When clinical suspicion of pulmonary embolism exists, simple chest X-ray and bilateral lower limb Doppler ultrasound are considered to be the initial examinations for guiding indication for V/Q scintigraphy, which should be preferable to CTPA when both are available. 45 Pharmacological stress with the use of vasodilators, either adenosine or dipyridamole, is not recommended during gestation, owing to the risks resulting from orthostatic hypotension. 2.4.1. Administration of Contrast Agents Iodinated contrast agents do not present any teratogenic effects, and they may be used orally or intravenously in cases where examination information is important for immediate management; otherwise, the examination should be postponed until after delivery. 46 This is due to the fact that fetal thyroid maturation begins at week 12, and it functions minimally at week 20 of gestation. There is, thus, a concern that iodinated contrast agents might induce development of hypothyroidism, even though, over the past 3 decades, there have been no reports of this occurring in this situation. In cases of allergic reaction to the contrast, phenylephrine and corticosteroids may be used safely. In preventive situations, prednisone and dexamethasone should be considered, given that most of these agents are metabolized in the placenta before reaching the fetus. There are, however, case reports of fetal adrenal suppression with corticosteroid use, and methylprednisone has been correlated to cleft lip when used before 10 weeks of gestation. 43 More recently, multislice tomography, with multiple rows of detectors, has been used, providing undeniable advantages, especially related to speed and definition in abdominal and angiographic studies (CT angiography). These benefits, however, have been accompanied by a significant increase in absorbed radiation doses in abdominal organs of around 90% to 180%, when compared to helical devices with a single row of detectors. At the same time that multislice technology is consolidated as an extremely useful tool for thoracic‑abdominal studies, it is necessary to invest in optimizing and adjusting protocols with the aim of controlling and limiting emitted radiation dose, especially during gestation. 2.4.2. Nuclear Magnetic Resonance Cardiac magnetic resonance (CMR) is advisable in cases where other non-invasive methods have not been sufficient to define diagnosis, and it is preferable to imaging examinations that emit ionizing radiation. Exposure during the first trimester of gestation has not been associated with harmful effects to fetuses or children during early childhood. Evidence regarding the use of gadolinium contrast during pregnancy is controversial. Gadolinium (Gd+3) is a paramagnetic metal ion whose pharmacological behavior in the organism is similar to that of iodinated contrast medium, i.e., it acts as an extracellular agent, rapidly spreading from the intravascular compartment to the interstitial space. No mutation or teratogenic effects have been documented following inadvertent administration of gadolinium-based contrast media during pregnancy. Nevertheless, depending on the dose, its use appears to be associated with greater risks of rheumatic, inflammatory, and infiltrative cutaneousmanifestations, in addition to fetal loss. 47 863