Acute management of supraventricular tachycardia and atrial fibrillation
For acute conversion of PSVT, vagal maneuvers are recommended and, if they fail, adenosine is the first drug of choice. Immediate electrical cardioversion is recommended only for those tachycardias with hemodynamic instability or for pre-excited AF. This procedure seems to be safe in all phases of pregnancy, there’s no evidence of fetal blood flow compromise, and the risk of inducing fetal arrhythmias or initiating preterm labor seems to be very small. After cardioversion, fetal heart rate control is advised. Another option in the acute phase is the use of intravenous (IV) beta-1-selective blockers such as metoprolol which can not only interrupt a PSVT but also control heart rate in an AF context. IV ibutilide or flecainide may be considered for atrial flutter and AF termination in stable patients with structurally normal hearts. Cardioversion obviously demands sedation and should be preceded by anticoagulation when appropriate (see below). A suggested workflow is available in figure 1.
It is important to avoid the use of amiodarone due to its consequences, such as disorders in thyroid function (thyroid insufficiency, hyperthyroidism, and goiter), bradycardia, impairment in fetal neurological development, and premature birth.