CLICK TO VIEW OTHER SECTIONS RELATED TO THIS TOPIC:
General Management Strategies
Because arrhythmias can be associated with structural heart disease, all women presenting with arrhythmias should have a complete cardiac examination, an electrocardiogram and a transthoracic echocardiogram. A search for provoking factor (e.g., hyperthyroidism, alcohol abuse) is important.
For women with significant arrhythmias, coordinated care with a heart specialist and a high-risk obstetrician should be implemented. The frequency of assessments during pregnancy should be determined on an individual basis.
Management of arrhythmia is based on the type of arrhythmia detected and the underlying cardiac condition. In general, treatment of arrhythmias during pregnancy is similar to treatment of arrhythmias in the non-pregnant state. However, because of potential adverse effects of anti-arrhythmic drugs on the fetus, they are typically only used when arrhythmias are associated with significant symptoms or hemodynamic compromise. Drug choice should take into account both expected efficacy and also fetal risk. Almost all antiarrhythmic drugs cross the placental barrier. The teratogenic effect of drugs occurs during organogenesis. The concerns with antiarrhythmic drug use during the 2nd and 3rd trimesters relate to their pro-arrhythmic effects and their effects on fetal growth and development. In general, controlled drug studies in pregnant women are lacking. Table 1 shows the drug classification of typical cardiac medications used during pregnancy. The potential fetal risks of all medications need to be discussed with the mother.
There is also a potential for adverse effects in infants exposed to antiarrhythmic drugs during breast feeding. Generally, the amount of antiarrhythmic drug excreted into breast mild is small. There are only few antiarrhythmic drugs (e.g., atenolol, amiodarone) which are contraindicated for the nursing mother. (4)
* Category A: Adequate, well-controlled studies in pregnant women have not shown an increased risk of fetal abnormalities to the fetus in any trimester of pregnancy
Category B: Animal studies have revealed no evidence of harm to the fetus, however, there are no adequate and well-controlled studies in pregnant women OR Animal studies have shown an adverse effect, but adequate and well-controlled studies in pregnant women have failed to demonstrate a risk to the fetus in any trimester.
Category C: Animal studies have shown an adverse effect and there are no adequate and well-controlled studies in pregnant women OR No animal studies have been conducted and there are no adequate and well-controlled studies in pregnant women.
Category D: Adequate well-controlled or observational studies in pregnant women have demonstrated a risk to the fetus. However, the benefits of therapy may outweigh the potential risk. For example, the drug may be acceptable if needed in a life-threatening situation or serious disease for which safer drugs cannot be used or are ineffective.
Category X: Adequate well-controlled or observational studies in animals or pregnant women have demonstrated positive evidence of fetal abnormalities or risks. The use of the product is contraindicated in women who are or may become pregnant.
† Except Atenolol
Drug doses may need to be modified during pregnancy because pregnancy can alter the absorption, excretion and plasma concentration of antiarrhythmic drugs.
Cardioversion should be used for any sustained tachycardia with hemodynamic compromise and may be considered for drug-refractory arrhythmias. While there is a theoretical risk of inducing arrhythmia in the fetus, this risk is very small due to the high fibrillation threshold and small amount of energy reaching the fetus. Nonetheless, fetal rhythm monitoring is recommended, because of reported cases of emergency cesarean section due to fetal arrhythmias.
Radiofrequency catheter ablation is usually not performed during pregnancy because of the associated ionizing radiation to the fetus.
Generally, vaginal deliveries are recommended unless there are obstetric indications for a cesarean delivery. Good pain management for labour and delivery is very important in order to minimize maternal cardiac stress.
To detect potential arrhythmias early, continuous monitoring with electrocardiography may be helpful in some instances.
