Chapter 21

### INTRODUCTION

With advances in medical and obstetric care, more and more women with cardiac disease are able to become pregnant and deliver a viable fetus. This chapter is divided into four main sections corresponding to four types of cardiac or cardiopulmonary disease that women may present with during pregnancy: valvular disease, congenital heart disease, cardiomyopathy, and pulmonary arterial hypertension. Although the incidence of ischemic/coronary heart disease may be increasing, we will not discuss it in this chapter, because there is much less experience and literature to guide therapeutic strategies in this area.

### VALVULAR DISEASE

The prevalence of valvular disease in pregnant women is low and has decreased with the decline of rheumatic fever in developed countries. Although rare, clinically significant valvular disease increases the risk of adverse maternal, fetal, and neonatal outcomes. Risk to the pregnant patient and developing fetus depends on the severity of the valvular lesion and underlying cardiac function. Ideally, patients with known valvular heart disease should be evaluated prior to conception; this should include a detailed history and physical examination, 12-lead electrocardiogram (ECG), and an echocardiogram with Doppler study. Pregnancy outcome and complications in patients with valvular disease can be closely correlated to prepregnancy New York Heart Association (NYHA) functional status and further to any deterioration of NYHA status during the pregnancy. In general, stenotic lesions are much more poorly tolerated during pregnancy than regurgitant lesions, because pregnancy usually requires, or at least causes, an increase in cardiac output, a process impaired by stenotic lesions and potentially causing decompensation.

#### Mitral Stenosis

##### Etiology/Risk Factors

Mitral stenosis (MS) is the most commonly encountered valvular lesion in pregnancy.1 Mitral stenosis usually occurs secondary to childhood rheumatic disease but may also be seen in association with congenital heart disease.

##### Pathophysiology

The normal mitral valve area determined by echocardiography is 4 to 5 cm2. A valve area of 1.5 to 2 cm2 is classified as mild stenosis, 1 to 1.5 cm2 as moderate, and less than 1 cm2 as severe. Stenosis of the mitral valve impedes blood flow from the left atrium to the left ventricle, creating a pressure gradient across the valve. As left ventricular filling is restricted, longer diastolic filling time is necessary to maintain ventricular preload and cardiac output. Accordingly, the left atrium enlarges and pulmonary venous and arterial pressures increase, eventually leading to pulmonary edema and right-sided heart failure. Left atrial enlargement can result in atrial dysrhythmias, particularly fibrillation, which can lead to significant sudden hemodynamic decompensation from the loss of the contribution of atrial contraction to ventricular filling.

The pressure gradient across the stenotic mitral valve will generally increase with pregnancy-associated increases in heart rate and blood volume. Tachycardia reduces diastolic filling time, which limits left ventricular filling through the stenotic valve, thus decreasing stroke volume. ...

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