A bicuspid aortic valve (BAV) is a congenital heart defect where the aortic valve has only two leaflets instead of the normal three. This can increase the risk of complications during pregnancy for women with a BAV. In a normal functioning aortic valve, the three leaflets open to allow blood to be pumped from the heart and then close to prevent backflow. With only two leaflets, a BAV may not function optimally, leading to problems like valve leakage, narrowing, calcification, and aortic enlargement. Understanding the risks associated with a BAV during pregnancy is important for managing maternal and fetal health.
Risks for the Mother
There are several risks that a pregnant woman with a BAV may face:
Aortic Dissection
An aortic dissection is a tear in the wall of the aorta, the major blood vessel that carries blood from the heart. This can be catastrophic and even fatal if not treated immediately. Pregnancy increases the risk of aortic dissection in women with a BAV due to the increased strain on the aorta from the higher blood volume and heart rate. The risk of dissection is highest during the third trimester and early postpartum period.
Aortic Enlargement or Aneurysm
BAV is associated with aortic enlargement or aneurysm formation. The increased hemodynamic stress of pregnancy can cause further stretching and damage to the aorta. About 1 in 10 pregnant women with BAV suffer from aortic enlargement. Rupture of an aortic aneurysm can be fatal.
Endocarditis
Endocarditis is an infection of the heart valves or inner lining of the heart. Pregnant women with BAV are at increased risk due to altered immune function and increased preload on the valve.
Heart Failure
Some pregnant women with BAV may develop heart failure, especially in the third trimester. This is usually precipitated by existing valve dysfunction. The high blood volume and cardiovascular demands of pregnancy can decompensate heart function in these women.
Arrhythmias
Abnormal heart rhythms such as atrial fibrillation may develop during pregnancy in women with BAV. This is often secondary to dysfunction of the aortic valve.
Risks for the Fetus
In addition to maternal risks, there are also potential risks to the developing fetus that need to be considered:
Miscarriage
The overall risk of miscarriage is not increased in women with BAV. However, the risk of miscarriage is higher if there is advanced valve dysfunction and heart failure.
Preterm Delivery
Women with moderate to severe valve dysfunction are more likely to undergo preterm delivery, either spontaneously or for medical reasons. The prevalence of preterm birth can be as high as 25%.
Intrauterine Growth Restriction
Impaired placental blood flow from maternal heart dysfunction can restrict oxygen and nutrient delivery to the fetus, resulting in poor growth. About 25% of pregnancies with BAV are affected by intrauterine growth restriction.
Stillbirth
There is an elevated risk of stillbirth associated with pregnancies complicated by BAV, thought to be related to placental insufficiency. The incidence of stillbirth is estimated to be about 2-4%.
Low Birth Weight
Due to intrauterine growth restriction or preterm delivery, infants born to mothers with BAV have an increased likelihood of low birth weight. The average birth weight is about 200-300g lower compared to the general population.
Management of Pregnancy with a Bicuspid Aortic Valve
Careful management is required for pregnant women with known BAV:
– All women with BAV should undergo comprehensive evaluation of their valve anatomy and function before pregnancy. This allows classification of their risk status.
– Fetal echocardiography should be offered during the second trimester to evaluate the baby’s heart and growth.
– For high risk women, frequent monitoring of the aorta with CT or MRI scans is recommended. Aortic diameter should be closely followed.
– Prophylactic antibiotics prior to delivery can lower endocarditis risk.
– Vaginal delivery is preferable in most cases. Cesarean section is reserved for obstetric indications only.
– In women with severe BAV dysfunction, early delivery may be planned. Similarly, early delivery may be needed in cases of rapid aortic enlargement.
– Treatment of heart failure and arrhythmias improves maternal and fetal outcomes. Medications safe in pregnancy should be chosen.
– Women with moderate or severe BAV complications should deliver in a tertiary care center with cardiothoracic surgery capabilities in case emergency aortic repair is needed.
– Close follow up for at least 6 months postpartum is advised to monitor recovery of cardiac function.
Conclusion
In summary, pregnant women with BAV are considered moderate to high-risk. The most serious maternal complications include aortic dissection and cardiac decompensation. Impaired fetal growth and preterm delivery are also concerns. Thorough evaluation of valve anatomy and function is key for risk stratification. Close monitoring, multidisciplinary care, and delivery at an advanced care center optimize outcomes in these high-risk pregnancies. With coordinated management, the majority of women with BAV can have successful pregnancies.
