Heart disease and pregnancy.

Cardiac disease affects approximately 2% of pregnancies in the Western world. Many guidelines reflect expert opinion formed on the basis of hemodynamic and physiologic changes.1 Anemia occurs because plasma volume increases more rapidly than does red blood cell mass. Enlargement of left ventricular mass and volume manifests itself as cardiomegaly on chest radiography and as left-axis deviation on electrocardiography. Higher cardiac output is caused early (during the 1st trimester) by increased stroke volume, and late (after week 20 of gestation) by a rise in heart rate. Fetal compression of the inferior vena cava (when the mother is in the supine position) can diminish cardiac output and thereby contribute to a hypercoagulable state. Blood glucose levels increase and should be monitored. Cholesterol levels increase as well but need not be monitored during pregnancy. Systemic vascular resistance should decrease; therefore, blood pressures >140/>90 mmHg are an indication for intervention (including medications), if cardiac risk factors exist. Blood pressures >170/>100 mmHg are an indication for hospitalization. During labor, cardiac output can increase by 80% (compared with 25% during caesarian section), which leads to fluctuations of blood pressure and venous return. Elevated blood pressure (afterload) on susceptible cardiac structures (such as the ascending aorta and the left ventricle) is therefore a basis for recommendations on mode of delivery. The heart rate normalizes during the 2 weeks after delivery, hemodynamics during 3 months, and left ventricular mass during 6 months. In the Western world, congenital heart disease accounts for approximately 80% of cardiac disease during pregnancy. In developing countries, rheumatic heart disease remains the most common cardiac disease during pregnancy (∼75%), whereas congenital heart disease is much less common (∼15%). In the United States, hypertensive disorders are the most frequent cardiovascular events, complicating approximately 7% of pregnancies. Peripartum cardiomyopathy2 is the most frequent cause of severe complications (∼1/2,000 pregnancies). In the United States, the mortality rate stands at <5%, with recurrence of disease in 30% to 50% of subsequent pregnancies. Risk factors include black race, multiparity, multiple fetuses, extremes of age, hypertension, diabetes mellitus, and smoking. Although peripartum cardiomyopathy has an unclear cause, standard heart-failure therapy—without angiotensin-converting enzyme inhibitors or angiotensin receptor blockers—is recommended during pregnancy. Some small studies suggest that bromocriptine has a positive effect. Acute coronary syndrome3 is rare (1–2/35,000 pregnancies) but carries a mortality rate of up to 10%. Spontaneous coronary artery dissection, thought to be related to the effects of progesterone, is one manifestation. The standard diagnostic approach—including history-taking, electrocardiography, and testing for biomarkers—is recommended. Coronary angiography (the radial approach if possible) with percutaneous coronary intervention, if necessary, is preferred over thrombolysis. The fetal radiation exposure ( 10 rads). As a final option for any cardiac condition refractory to medical management, surgery using cardiopulmonary bypass can be considered. The preferred timing for surgery is the 2nd trimester. If surgery is delayed beyond the 2nd trimester, delivery (with prepartum steroids) is preferred before surgery, due to preterm labor during the 3rd trimester. Because of thromboembolism, mechanical heart valves are a significant cause of morbidity and—in up to 15% of affected patients—of death. Anticoagulation options include unfractionated heparin or low-molecular-weight heparin as a bridge to warfarin, which has a dose-dependent embryopathy rate of <10%. Hospitalization is recommended for any change in anticoagulation regimen, and caesarian section is indicated if the mother is on warfarin, due to the drug's ability to cross the placenta. Newer agents like dabigatran and apixaban are not recommended. Arrhythmias, in general, are treated as they are in nonpregnant patients. Cardioversion and adenosine are safe. The β-blockers, except for atenolol, tend to be the agents of choice for rate control. Cardioversion for all ventricular tachycardia is the first-line therapy. Since the time of guideline revisions in 1997, prophylaxis for subacute bacterial endocarditis has not been indicated for vaginal or caesarian-section delivery, or for intrauterine device placement or retrieval. Endocarditis is rare (1/100,000 pregnancies) and the 2007 guidelines suggest prophylaxis only when a high-risk condition (for example, cyanotic heart disease, a prosthetic valve, or prior endocarditis) is present during the performance of a high-risk procedure (for example, dental surgery).4 Contraindications to pregnancy include pulmonary hypertension, severe systemic ventricular dysfunction (or residual dysfunction from peripartum cardiomyopathy), severe left-sided obstructive lesions (if aortic stenosis is symptomatic: see Fig. 1), or a dilated aortic root (45 mm with Marfan syndrome or 50 mm with bicuspid aortic valve). Cyanosis with a baseline oxygen saturation level of 85% chance that pregnancy will not result in a live birth. Conversely, a baseline oxygen saturation level of >90% enables a >90% chance of a live birth. The CARPREG risk score5 (Table I) accounts for cardiac pregnancy risk by assigning points for poor functional class (New York Heart Association functional class III or IV, or cyanosis), mild-to-moderate left-sided obstruction, prior cardiac event, and systemic ventricular ejection fraction of 1 conveys 75%. A score of >1 calls for caesarian-section delivery or (in some instances) for termination of pregnancy. All other risk factors (with rare exceptions) are sufficiently insubstantial to allow vaginal delivery, which is less expensive and carries lower risk of infection, thrombosis, and bleeding. The World Health Organization recommends cardiology consultation and follow-up in accordance with risk stratification.6 TABLE I. CARPREG Score Fig. 1 Transthoracic echocardiogram (parasternal long-axis view with color-flow Doppler comparison) reveals severe aortic stenosis due to dysplastic bicuspid valve after multiple balloon dilations between pregnancies. In discussing contraception, the doctor and patient should include the risk of pregnancy, thrombotic potential, fluid retention, blood loss, and the risk of anesthesia. Low-risk office-based sterilization (for example, Essure®, Conceptus Incorporated; Mountain View, Calif) is available for the highest-risk patients.