Cardiac disease in pregnancy and pulmonary hypertension



Synonyms and Keywords: pulmonary artery hypertension, PAH

Overview
Pulmonary hypertension, defined as mean pulmonary artery pressure of greater than 25 mmHg at rest or 30 mmHg with exercise, carries a higher mortality when it is associated with pregnancy. It carries a significant risk to mother and child during pregnancy; as a result, mothers require careful monitoring.

Physiologic Considerations in Pregnancy
As reviewed in Physiologic Changes Associated with Pregnancy, maternal blood volume increases throughout pregnancy until between 28 and 34 weeks of gestation, and circulating blood volume is increased to between 30% and 50% above the non-pregnant state. Red blood cell mass increases to approximately 25% above the non-pregnant state. Cardiac output increases through various mechanisms, and hypercoagulability is noted in the postpartum state due to relative resistance to activated protein C, reduced serum levels of protein S and increased levels of factors I, II V, VII, VIII, X and XII.

All of these changes can be particularly deleterious in patients with PAH. It can be very harmful if a thrombus forms or embolizes to an already compromised pulmonary circulation. Such hematological changes present a significant risk, and mortality is between 30% and 50% for pregnant women with idiopathic PAH.

Specific Issues with PAH and Pregnancy

 * Longterm elevation of pulmonary vascular resistance may cause right ventricular hypertrophy or dilatation, tricuspid regurgitation or arrhythmias, leading to intolerance of the increased heart rate and circulating blood volume of pregnancy.
 * Cardiac output may already be reduced by pulmonary hypertension, and the heart may not be able to increase cardiac output in proportion to the reduced systemic vascular resistance that occurs during pregnancy.
 * Normal adaptive changes in the lungs to accommodate the increased pulmonary blood flow may be prevented by fixed vascular remodeling.
 * Hypercoagulability may increase the tendency for thrombus formation, which may be poorly tolerated (as above).
 * Patients are at risk for sudden cardiac death from a pulmonary hypertensive crises, malignant arrhythmias or pulmonary thromboembolism.
 * Patients can sustain a stroke as a result of intracardiac shunting in pre-existing Eisenmenger’s syndrome or if there is a persistent patent foramen ovale

Outcomes and Recommendations
In a review of PAH and pregnancy outcomes between 1978 and 1996, Weiss and colleagues found a maternal mortality rate of 30% in idiopathic PAH, 36% in Eisenmenger’s syndrome and 56% in pulmonary hypertension secondary to a variety of other conditions including liver disease, connective tissue disease, chronic thromboembolic events and ingestion of weight loss agents. Of note, the highest mortality was in the first month after delivery.

As a result, many authors recommend pregnancy should be avoided in the setting of maternal PAH. . See guidelines below.

==ACC/AHA 2008 Guidelines: Pulmonary hypertension/Eisenmenger physiology == {{cquote|

Class I
1. Women with severe congenital heart disease-pulmonary arterial hypertension, especially those with Eisenmenger physiology, and their partners should be counseled about the absolute avoidance of pregnancy in view of the high risk of maternal death, and they should be educated regarding safe and appropriate methods of contraception. (Level of Evidence: B)

2. Women with congenital heart disease-pulmonary arterial hypertension who become pregnant should:


 * a. Receive individualized counseling from cardiovascular and obstetric caregivers collaborating in care and with expertise in management of congenital heart disease-pulmonary arterial hypertension. (Level of Evidence: C)


 * b.Undergo the earliest possible pregnancy termination after such counseling. (Level of Evidence: C)


 * c. Surgical sterilization carries some operative risk for women with congenital heart disease-pulmonary arterial hypertension but is a safer option than pregnancy. In view of advances in minimally invasive techniques, the risks and benefits of sterilization modalities should be discussed with an obstetrician experienced in management of high-risk patients, as well as with a cardiac anesthesiologist. (Level of Evidence: C)

Class IIB
1. Pregnancy termination in the last 2 trimesters of pregnancy poses a high risk to the mother. It may be reasonable, however, after the risks of termination are balanced against the risks of continuation of the pregnancy. (Level of Evidence: C)

Class III
1. Pregnancy in women with congenital heart disease-pulmonary arterial hypertension, especially those with Eisenmenger physiology, is not recommended and should be absolutely avoided in view of the high risk of maternal mortality. (Level of Evidence: B)

2. The use of single-barrier contraception alone in women with congenital heart disease-pulmonary arterial hypertension is not recommended owing to the frequency of failure. (Level of Evidence: C)

3. Estrogen-containing contraceptives should be avoided. (Level of Evidence: C)}}

Management of Patients with PAH During Pregnancy
A multidisciplinary team should be involved in management, and specific therapeutic options include:
 * Oxygen to maintain maternal PaO2 above 70 mmHg


 * Diuretics for patients with PAH who develop right heart failure, under careful supervision


 * Anticoagulation, often with the assistance of a hematologist. The agent of choice is a low-molecular-weight heparin with serial measurement of anti-factor Xa levels.


 * Pulmonary vasoactive agents:
 * Endothelin receptor antagonists are contraindicated during pregnancy because of risks of teratogenicity. Alternative agents include:
 * Sildenafil
 * Intravenous Epoprostenol (Prostacyclin)
 * In the acute situation, inhaled Nitric Oxide


 * Atrial septostomy

Guideline Resources
ACC/AHA 2008 Guidelines for the Management of Adults With Congenital Heart Disease