Chapter 11: Pulmonary Hypertension

INTRODUCTION

Cardiac disease is a frequent cause of morbidity and mortality during pregnancy.^1,2 In the past, mitral stenosis because of rheumatic heart disease was the most common cause of cardiac disease associated with pregnancy; however, two registries indicate that congenital heart disease is the most prevalent form of heart disease complicating pregnancy.^3,4 Notably, mitral stenosis and congenital heart disease are associated with the development of pulmonary vascular disease. However, congenital heart disease associated with pulmonary hypertension and idiopathic pulmonary arterial hypertension (PAH) are significant causes of morbidity and mortality in the parturient with case series indicating a 30% to 56% maternal and 9.5% fetal mortality.^2,5 PAH affects young women, and advances in therapies have allowed women with PAH to survive to childbearing years thereby resulting in a greater number of parturients with this disease process.⁶ Yet, consensus guidelines recommend that women with pulmonary hypertension, who are of child bearing potential, use effective contraception to avoid pregnancy and in the event of pregnancy, early termination is advised.⁷ Although these recommendations are medically justifiable, some patients become pregnant against medical advice or consider pregnancy termination as morally objectionable.^8,9,10 Hence, prenatal counseling concerning contraception and management during and after pregnancy are important issues in this group. This chapter will focus on management of PAH during and after pregnancy in the current era of PAH-specific therapies.

Pulmonary hypertension, defined as mean pulmonary artery pressure ≥25 mmHg, extends to include PAH, pulmonary venous hypertension characterized by left ventricular systolic or diastolic dysfunction and valvular heart disease (mitral or aortic), chronic lung disease and/or hypoxia characterized by chronic obstructive pulmonary disease, cystic fibrosis, interstitial lung disease, sleep disordered breathing, and chronic thromboembolic pulmonary hypertension¹¹ (Table 11-1). PAH is a rare, progressive disease characterized by an elevated pulmonary vascular resistance often leading to right ventricular failure and death if untreated. The consensus definition for PAH, based on hemodynamics, is a mean pulmonary artery pressure ≥25 mmHg and pulmonary capillary wedge pressure ≤15 mmHg.¹² Furthermore, the histopathologic features of PAH are represented as a chronic vascular condition primarily affecting small pulmonary arteries with characteristic features that include arteriole muscular hypertrophy, intimal hyperplasia, and plexiform lesions.¹³ Thus, PAH encompasses hemodynamic and histopathologic features of a group of conditions that include idiopathic PAH (formerly termed primary pulmonary hypertension) and pulmonary hypertension associated with congenital heart disease, connective tissue disorders, portal hypertension, human immunodeficiency virus (HIV) infection, medications (fenfluramine), and illicit drugs (methamphetamine) (Table 11-1).¹¹