The risk of radiation exposure to the fetus is a concern with catheter ablation in pregnant patients, because high-dose ionizing radiation has been linked to excess malignancy and congenital malformations.528 However, the fetal radiation dose for most common cardiovascular interventions is not likely to exceed the 50-mGy negligible-risk threshold dose for excess malignancy.529 One study that used phantoms to simulate pregnancy estimated a low lifetime risk of malignancies from radiation exposure to the conceptus during a typical ablation procedure.527 Furthermore, with current technologies such as electroanatomic mapping systems, catheter ablation procedures using minimal or even zero fluoroscopy have been described in pregnant women.526 Thus, if a catheter ablation procedure is required in a pregnant woman, radiation-reduction technologies should be used, and the procedure should be avoided in the first trimester when the teratogenic risk is greatest.528 Of note, shielding the fetus by covering the mother with a lead apron does not eliminate radiation to the fetus because most of the radiation to the fetus comes from scatter. IIb C-LD Oral amiodarone may be considered for ongoing management in pregnant patients when treatment of highly symptomatic, recurrent SVT is required and other therapies are ineffective or contraindicated.517,523 See Online Data Supplement 20. Although oral amiodarone has been administered safely during pregnancy, multiple adverse effects to the fetus have also been reported.523 An important concern is the possibility of fetal hypothyroidism, reported in approximately 17% of cases.517,523 Therefore, fetal monitoring for development of goiter with ultrasound and for signs of clinical hypothyroidism is advised. In addition, amiodarone has the potential for direct neurotoxicity, which may lead to neurodevelopmental abnormalities.523 Page et al 2015 ACC/AHA/HRS SVT Guideline e555 9.4. SVT in Older Populations 9.4.1. 