Cardiac disease in pregnancy and valvular heart disease

Overview
Rheumatic heart disease remains prevalent in developing countries but is less common in Western countries. Mitral stenosis therefore complicates pregnancy less frequently and Western countries. Bicuspid aortic stenosis, mitral regurgitation, aortic regurgitation, and prosthetic valves can all be problematic during pregnancy due to physiologic hemodynamic changes.


 * For a general overview of valvular heart disease, click here.

Mitral Stenosis

 * Most hemodynamically important valvular heart disease during pregnancy

Pathophysiology:

 * Increase in cardiac output coupled with the increase in heart rate shortens the diastolic filling time.
 * The short and diastolic filling time in turn increases the mitral valve gradient.

Screening:

 * Patients should have echocardiography prior to proceeding with pregnancy.
 * Exercise echocardiography may be warranted.

Management:

 * Restriction of physical activity and salt intake. Avoid supine position.
 * Judicious use of diuretics and beta-blockade are appropriate in symptomatic cases to lengthen disatolic filling period.
 * Consideration of invasive monitoring.
 * Replace blood losses during delivery carefully.
 * Percutaneous balloon mitral valvuloplasty has been utilized in symptomatic cases (Class III,IV).

Complications:

 * Atrial fibrillation can lead to rapid deterioration.
 * Volume shifts during delivery can result in pulmonary hypertension or pulmonary edema.


 * For further information, click here

Mitral Regurgitation

 * Fairly well tolerated in pregnancy.
 * The left ventricle tends to dilate as pregnancy progresses, and this may worsen mitral regurgitation.
 * Vasodilators only if systemic HTN is present (avoid ACE-inhibitors).
 * Antibiotic prophylaxis important if infection suspected.
 * Early delivery is sometimes necessary in case of maternal hemodynamic instability.


 * For further information, click here

Aortic Insufficiency

 * As with mitral regurgitation, fairly well tolerated.
 * Severity may decrease during pregnancy due to drop in systemic vascular resistance.
 * Vasodilators only if systemic HTN is present (avoid ACE-inhibitors).
 * Antibiotic prophylaxis important if infection suspected.
 * Closer monitoring is warranted, early delivery may be necessary.


 * For further information, click here

Aortic Stenosis

 * Generally due to bicuspid aortic valve.
 * Fixed cardiac output in response to stress.
 * Moderate stenosis may be tolerated in a compliant patient who is monitored closely.
 * Severe cases have maternal mortality up to 17% and fetal mortality up to 32%.
 * Aortic root dilation > 4.5cm is a contraindication to pregnancy.
 * Any reduction in preload can lead to cardiac or cerebral ischemia and compromised uterine flow.
 * Aortic balloon valvuloplasty has been safely performed in a small subset of pregnancy patients with some success, as described by Myerson et al.


 * For further information, click here

==Prosthetic Valves and Pregnancy ==

Mechanical Prosthetic Valves
Mechanical valves can be problematic in pregnancy, due to the requirement for anticoagulation. Regardless of the strategy used, there is a higher chance of fetal loss, placental hemorrhage, and prosthetic valve thrombosis.

Tissue Prosthetic Valves
Tissue valves have less thrombogencity than mechanical valves. As a result, they do not routinely involve the use of warfarin/anticoagulation. For a more thorough discussion on tissue valves, click here.

===Managing Prosthetic Valves During Pregnancy ===


 * Pregnancy is a thrombogenic milieu.
 * Coumadin use during 1st trimester is associated with warfarin embryopathy and when used in 2nd or 3rd trimesters, it is postulated to cause CNS abnormalities.
 * Keeping Coumadin dose ≤ 5.0 mg/day appears to be safe.
 * Recommendations based more on opinion than scientific evidence.
 * Subacute bacterial endocarditis prophylaxis at delivery.

Antibiotic Prophylaxis
AHA recommendation is that antibody prophylaxis is not necessary for an uncomplicated delivery except among patients with a prosthetic heart valve or surgically constructed systemic to pulmonary shunt. However, because of the difficulties in predicting complicated deliveries and the potential devastating consequences of endocarditis, antibiotic prophylaxis for vaginal delivery in all patients with congenital heart disease expect those with an isolated secundum type atrial septal defect and those six months or more after repair of septal defects or surgical ligation division of a patent duct is arteriosus, seems reasonable. At the time of delivery, it is recommended that all women with valvular heart disease receive antibiotics, usually penicillin and gentamycin. For those with a pencillin allergy, vancomycin is used.

===ACC/AHA Guideline: Recommendations for Anticoagulation during Pregnancy ===

1. The decision whether to use heparin during the first trimester or to continue oral anticoagulation throughout pregnancy should be made after full discussion with the patient and her partner; if she chooses to change to heparin for the first trimester, she should be made aware that heparin is less safe for her, with a higher risk of both thrombosis and bleeding, and that any risk to the mother also jeopardizes the baby.

2. High-risk women (a history of thromboembolism or an older- generation mechanical prosthesis in the mitral position) who choose not to take warfarin during the first trimester should receive continuous unfractionated heparin intravenously in a dose to prolong the mid-interval (6 h after dosing) activated partial thromboplastin time to 2 to 3 x control value. Transition to warfarin can occur thereafter.

3. In patients receiving warfarin, the international normalized ratio should be maintained between 2.0 and 3.0 with the lowest possible dose of warfarin, and low-dose aspirin should be added.

4. Women at low risk (no history of thromboembolism, newer low- profile prosthesis) might be managed with adjusted-dose subcutaneous heparin (17,500 to 20,000 U twice daily to prolong the mid-interval (6 h after dosing) activated partial thromboplastin time to 2 to 3 x control value.

5. Warfarin should be stopped no later than week 36 and heparin substituted in anticipation of labor.

6. If labor begins during treatment with warfarin, a cesarean section should be performed.

7. In the absence of significant bleeding, heparin can be resumed 4–6 h after delivery, and warfarin begun orally.

===Seventh ACCP Conference Recommendation: Antithrombotic and Thrombolytic Therapy during Pregnancy in patients with Prosthetic Heart Valve === {{cquote|

Grade 1
1. Adjusted-dose, twice-daily LMWH throughout pregnancy in doses adjusted either to keep a 4-hour postinjection anti-Xa heparin level at approximately 1.0 to 1.2 U/mL (preferable) or according to weight (Level of Evidence: C), or

2. Aggressive adjusted-dose UFH throughout pregnancy: i.e., administered subcutaneous every 12 hours in doses adjusted to keep the mid-interval aPTT at least twice control or to attain an anti-Xa heparin level of 0.35 to 0.70 U/mL (Level of Evidence: C), or

3. UFH or LMWH until the thirteenth week, change to warfarin until the middle of the third trimester, and then restart UFH or LMWH (Level of Evidence: C)


 * Remark: Long-term anticoagulants should be resumed postpartum with all regimens

Grade 2
1. In women with prosthetic heart valves at high risk, the guideline developers suggest the addition of low-dose aspirin, 75 to 162 mg/day (Level of Evidence: C)}}