Successful treatment of fetal supraventricular tachycardia with maternal digoxin therapy

Drugs in pregnancy: Pharmacologic and physiologic changes that affect clinical care

Pharmacologic interventions play a major role in obstetrical care throughout pregnancy, labor and delivery and the postpartum. Traditionally, obstetrical providers have utilized standard dosing regimens developed for non-obstetrical indications based on pharmacokinetic knowledge from studies in men or non-pregnant women. With the recognition of pregnancy as a special pharmacokinetic population in the late 1990s, investigators have begun to study drug disposition in this unique patient dyad. Many of the basic physiologic changes that occur during pregnancy have significant impact on drug absorption, distribution and clearance. Activity of Phase I and Phase II drug metabolizing enzymes are differentially altered by pregnancy, resulting in drug concentrations sufficiently different for some medications that efficacy or toxicity is affected. Placental transporters play a major dynamic role in determining fetal drug exposure. In the past two decades, we have begun to expand our understanding of obstetrical pharmacology; however, to truly optimize pharmacologic care of our pregnant patients and their developing fetus, additional research is critically needed.

Antiarrhythmic drugs in pregnancy

During pregnancy a number of rhythm disturbances can occur in both the mother and fetus; these may range from benign ectopy to life-threatening arrhythmias. With a clear understanding of the maternal hemodynamic changes associated with pregnancy, and the appropriate antiarrhythmic therapies available, almost all such cases can be treated successfully. Although no drug is completely safe, most are well tolerated and can be given with relatively low risk. Drug therapy should be avoided during the first trimester of pregnancy if possible and drugs with the longest record of safety should be used as first-line therapy. Conservative therapies should be used when appropriate. Several drug options exist for most maternal and fetal arrhythmias.

Transplacental passage of digoxin in the case of nonimmune hydrops fetalis

Successful treatment of intrauterine fetal tachyarrhythmia was reported in several cases recently. It was also pointed out that placental transfer of digoxin is unsatisfactory under certain conditions. However, it has not been clearly shown in which cases fetal digoxin level does not reach the maternal level. We present a case of nonimmune hydrops fetalis due to congenital atrial flutter in which digoxin concentration in the sera of the mother and the neonate showed significant dissociation, and discuss perinatological matters about the digoxin treatment and the factor that obstructs the transplacental passage of digoxin. Conclusively, we recommend that maternal digoxin concentration should be raised to near toxic level if the resolution of fetal and placental hydrops is not attained in the initial digoxin loading.