Pulmonary artery dilatation during normal pregnancy

Background: During pregnancy the cardiovascular system undergoes complex alterations; however, there have been few studies concerning pulmonary artery behaviour during gestation. Aim: The aim of this study was to evaluate changes in the pulmonary artery diameter (PAD) during gestation, with respect to left ventricular (LV) load and remodelling, as well as to systemic vascular resistance (SVR). Methods: It was a prospective cohort study, which included 69 consecutive healthy outpatient women with a singleton pregnancy. Echocardiography and ultrasonography of the uterine arteries were performed at two visits (V1 and V2) during pregnancy, and only echocardiography at one visit postpartum. Results: Pulmonary artery diameter increased in all women, from 20.0 mm at V1 to 22.7 mm at V2 (p < 0.001), and it returned to the reference range postpartum (19.5 mm; p < 0.001 vs. V2). Echocardiography did not reveal any other abnormalities, including the signs of intracardiac shunt or right ventricular pressure overload. During V2, PAD positively correlated with the following echocardiographic parameters: LV end-diastolic diameter (r = 0.386; p = 0.002), LV end-systolic diameter (r = 0.345 p = 0.006), LV end-diastolic volume (r = 0.308; p = 0.016), LV mass (r = 0.459; p < 0.001), left atrial area (r = 0.334; p = 0.009), LV cardiac output (r = 0.338; p = 0.011), and aortic diameter (r = 0.369; p = 0.003). Furthermore, there was a negative linear correlation between PAD and SVR (r = –0.307; p = 0.025) and pulsatility index (r = –0.318; p = 0.012). Conclusions: Our study shows pulmonary artery dilatation in healthy pregnant women without any other abnormal echocardiographic findings. These changes in PAD are associated with volume overload and low vascular resistance, and during postpartum they usually subside.