Discussion of Pregnancy in Primary Pulmonary Hypertension (PPH)

An early case series reported a 50% mortality rate associated with pregnancy and Primary Pulmonary Hypertension (PPH).A more recent account noted a 30% mortality rate and partly attributed the decline in the mortality rate to earlier recognition, better understanding of the pathophysiology of Primary Pulmonary Hypertension (PPH), along with improvements in medical therapy and critical-care obstetrics. Recognition of the elevated maternal-fetal mortality rate has led physicians to recommend effective contraception and, in the event of a pregnancy, early fetal termination. The maternal mortality rate is related principally to the increased demands on the cardiopulmonary system during pregnancy. Under normal circumstances, increases in cardiac output in the range of 30 to 50%, blood volume in the range of 40 to 50%, and oxygen consumption of 20% are observed during pregnancy. Other physiologic changes include an increase in cardiac output during labor in patients receiving local anesthesia (pudendal block) and postpartum intravascular volume shifts resulting from blood loss or diuresis. These physiologic events place a great demand on the cardiovascular system, with the greatest incidence of mortality occurring during the first several postoperative days. This is likely related to changes in pulmonary vascular tone due to intravascular volume shifts, hypoxemia, elevated catecholamine levels, or thromboembolism. Identification of the hemodynamic changes has led to the use of anticoagulants, oxygen, and vasodilators in the management of these patients.

Several reports have demonstrated an improvement in hemodynamics and outcome in nonpregnant patients receiving vasodilator and anticoagulation therapy for the treatment of Primary Pulmonary Hypertension (PPH). Subsequently, several reports have described the use of vasodilator therapy during parturition and postpartum with good outcomes. The majority of patients in these series had improvements in hemodynamics similar to our patient, leading one to speculate that a favorable short-term response to vasodilator therapy may be predictive of a favorable maternal outcome. Accordingly, we elected to use epoprostenol and heparin for several weeks prior to the expected date of delivery in order to maximize the benefits of this therapy. Furthermore, this therapy was continued in the postpartum period given the increased incidence of complications following labor and delivery. Another important point concerns the safety of the fetus following exposure to IV epoprostenol. Although there is little information on this subject, this report indicates that during the last trimester of pregnancy epoprostenol therapy does not result in any fetal deformities or growth retardation.

Several factors have been implicated as potential risk factors for maternal death, including mode of delivery, type and technique of anesthesia, and manner of maternal monitoring. A recent case series described successful outcomes in seven women with Primary Pulmonary Hypertension (PPH) following vaginal delivery. In contrast, greater morbidity and mortality has been associated with the performance of a cesarean section. To our knowledge, this is one of a small number of reports noting a successful maternal-fetal outcome following cesarean section in a patient with Primary Pulmonary Hypertension (PPH). An explanation for this observation has been offered and may be related to the selection of the anesthetic technique (epidural or general anesthesia), although it is not clear whether one technique is superior in the setting of Primary Pulmonary Hypertension (PPH) on and parturition. Another explanation may lie in the fact that cesarean section is more likely to be performed in patients unable to deliver by the vaginal route who subsequently develop hemodynamic instability. While some authors have disputed the need for a PAC, we advocate its use intraoperatively and during the postpartum period. In this report, the epoprostenol infusion was titrated using pulmonary artery pressure and cardiac output measurements obtained with a PAC. An important component in the successful management of these patients involves a multidisciplinary team approach with an obstetrician, pulmonary or cardiology specialist, anesthesiologist, and experienced nursing staff.

In summary, Primary Pulmonary Hypertension (PPH) is likely to worsen during labor and delivery, resulting in a high maternal mortality rate. Early recognition and treatment with vasodilator and anticoagulation therapy may reduce the likelihood of complications. Elective cesarean section may be performed with intraoperative vasodilator administration. The IV epoprostenol dose not give rise to physical deformities or fetal growth retardation. A multidisciplinary approach to the management of patients with Primary Pulmonary Hypertension (PPH) during pregnancy is of great importance for a successful maternal-fetal outcome.