The number of drugs that have been used for the correction of fetal arrhythmias reflects the amount of uncertainty about dosage, effectiveness, and hazards. Fetal pharmacokinetic studies are not available, and dosage schedules for these very immature infants are uncertain or derived from data on older and bigger infants and children. Thus, consider each case individually; be aware that therapeutic misadventures remain possible if not probable.
These are used for fetal cardiac failure. Positive inotropic agents (eg, digoxin) increase force of contraction of myocardium and are used to treat acute and chronic CHF. Digoxin may also be used for fetal supraventricular tachycardia (SVT) because it decreases AV conduction.
Recommended dosages require considerable modification because of individual variations in sensitivity to drug in adults, children, and (probably) fetuses. Usually administered to mother; thus, adult dosages are used. Transplacental transfer is normally excellent; however, impaired fetal perfusion of placental circulation due to severe cardiac failure results in impaired drug pickup; thus, fetal drug levels may be much lower than maternal concentrations.
These are used to treat fetal edema. They promote excretion of water and electrolytes by kidneys and are used to treat heart failure or hepatic, renal, or pulmonary disease when sodium and water retention has resulted in edema or ascites.
Diuretic, in conjunction with digoxin, that has been used in management of fetal hydrops. Both transplacental (maternal administration) and direct fetal routes have been used. No satisfactory pharmacokinetic data are available to support these recommendations.
These agents alter electrophysiologic mechanisms responsible for arrhythmia and are used to treat fetal arrhythmia.
Limited use in fetus.
Recent use has been promising; however, most information is in form of case reports.
Use in children well established; however, little data available on use in preterm neonate or fetus.
Recent use in fetal arrhythmias has been promising; however, data are scarce, and definitive pharmacokinetic studies have not been performed.
Limited data from infants suggest that half-life at birth may be prolonged. These data have not been extended backward to fetal life. Maternal (transplacental) use, in conjunction with digoxin, has been promising anecdotally.
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