Cardiac disease in pregnancy and valvular heart disease

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Special Scenarios: I. Pre-existing Cardiac Disease: Congenital Heart Disease Repaired Congenital Heart Disease Pulmonary Hypertension Rheumatic Heart Disease Connective Tissue Disorders II. Valvular Heart Disease: Mitral Stenosis Mitral Regurgitation Aortic Insufficiency Aortic Stenosis Mechanical Prosthetic Valves Tissue Prosthetic Valves III. Cardiomyopathy: Dilated Cardiomyopathy Hypertrophic Cardiomyopathy Peripartum Cardiomyopathy IV. Cardiac diseases that may develop During Pregnancy: Arrhythmias Acute Myocardial Infarction Hypertension
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-In-Chief: Anjan K. Chakrabarti, M.D. [2]; Lakshmi Gopalakrishnan, M.B.B.S. [3]

Overview

Rheumatic heart disease remains prevalent in developing countries but is less common in Western countries. Mitral stenosis therefore complicates pregnancy less frequently in 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.

Specific Issues with Valvular Disease in Pregnancy

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.
• The occurrence of atrial fibrillation may put the patient in atrial fibrillation and the associated rapid heart rate with reduced diastolic filling time may lead to pulmonary edema.

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.
• Anticoagulation may be necessary in the presence of atrial fibrillation.
• 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 about mitral stenosis in general, 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 about mitral regurgitation, 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 > 4.5 cm 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 on aortic stenosis, 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 on aortic insufficiency, 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 may be associated with CNS abnormalities. Despite this risk, warfarin is often used in the second and third trimesters.
• Given the risk of embryopathy the during the first trimester, heparin is often used early in pregnancy. Heparin is resumed near the time of labor. If used during the first trimester, the dose should be kept under 5 mg every 24 hours.
• 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.

2008 and Incorporated 2006 ACC/AHA Guidelines for the Management of Patients with Valvular Heart Disease (DO NOT EDIT)

Anticoagulation Regimen in Pregnant Patients with Mechanical Prosthetic Valves (DO NOT EDIT)

Class I

"1. All pregnant patients with mechanical prosthetic valves must receive continuous therapeutic anticoagulation with frequent monitoring. (Level of Evidence: B)"

"2. For women requiring long-term warfarin therapy who are attempting pregnancy, pregnancy tests should be monitored with discussions about subsequent anticoagulation therapy, so that anticoagulation can be continued uninterrupted when pregnancy is achieved. (Level of Evidence: C)"

"3. Pregnant patients with mechanical prosthetic valves who elect to stop warfarin between weeks 6 and 12 of gestation should receive continuous intravenous UFH, dose-adjusted UFH, or dose-adjusted subcutaneous LMWH. (Level of Evidence: C)"

"4. For pregnant patients with mechanical prosthetic valves, up to 36 weeks of gestation, the therapeutic choice of continuous intravenous or dose-adjusted subcutaneous UFH, dose-adjusted LMWH], or warfarin should be discussed fully. If continuous intravenous UFH is used, the fetal risk is lower, but the maternal risks of prosthetic valve thrombosis, systemic embolization, infection, osteoporosis, and heparin-induced thrombocytopenia are relatively higher. (Level of Evidence: C)"

"5. In pregnant patients with mechanical prosthetic valves who receive dose-adjusted LMWH, the LMWH should be administered twice daily subcutaneously to maintain the anti-Xa level between 0.7 and 1.2 U per ml 4 h after administration. (Level of Evidence C)"

"6. In pregnant patients with mechanical prosthetic valves who receive dose-adjusted UFH, the aPTT should be at least twice control. (Level of Evidence C)"

"7. In pregnant patients with mechanical prosthetic valves who receive warfarin, the INR goal should be 3.0 (range 2.5 to 3.5). (Level of Evidence: C)"

"8. In pregnant patients with mechanical prosthetic valves, warfarin should be discontinued and continuous intravenous UFH given starting 2 to 3 weeks before planned delivery. (Level of Evidence: C)"

Class III

"1. LMWH should not be administered to pregnant patients with mechanical prosthetic valves unless anti-Xa levels are monitored 4 to 6 h after administration. (Level of Evidence: C)"

"2. Dipyridamole should not be used instead of aspirin as an alternative antiplatelet agent in pregnant patients with mechanical prosthetic valves because of its harmful effects on the fetus. (Level of Evidence: B)"

Class IIa

"1. In patients with mechanical prosthetic valves, it is reasonable to avoid warfarin between weeks 6 and 12 of gestation owing to the high risk of fetal defects. (Level of Evidence: C)"

"2.In patients with mechanical prosthetic valves, it is reasonable to resume UFH 4 to 6 h after delivery and begin oral warfarin in the absence of significant bleeding. (Level of Evidence: C)"

"3. In patients with mechanical prosthetic valves, it is reasonable to give low-dose aspirin (75 to 100 mg per day) in the second and third trimesters of pregnancy in addition to anticoagulation with warfarin or heparin. (Level of Evidence: C)"

2005 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

“

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)

”

Sources

• 2008 ACC/AHA Guidelines incorporated into the 2006 guidelines for the management of patients with valvular heart disease
• 2005 ACC/AHA Guideline Recommendations for Anticoagulation during Pregnancy
• Seventh ACCP Conference Recommendation: Antithrombotic and Thrombolytic Therapy during Pregnancy in patients with Prosthetic Heart Valve

References

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