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.