Pregnancy results in a significant increase in cardiac output and pulmonary blood flow, reduction in pulmonary vascular resistance, without change in pulmonary arterial pressures. The impact of these physiologic changes on the main pulmonary artery (MPA) size is not studied. Our purpose is to compare the size of pulmonary arteries in pregnancy on CT pulmonary angiograms (CTPA) to that of historical controls.
Normal CTPAs performed in pregnancy for suspected pulmonary embolism were retrieved. Diameters of MPA, ascending (ASAO) and descending aorta (DESAO), right and left pulmonary arteries (RPA and LPA)were measured according to standards. Mean values and standard deviations (SD) of each diameter and the ratio of MPA/ASAO and MPA/DESAO were calculated.
98 studies were reviewed. Mean age was 28. Mean diameter, SD and range in mm were: MPA 28 ± 3.5 (20–40); RPA 16 ± 3.3 (10–24); LPA 17 ± 2.8 (9–25). Mean ratios, SD and range in mm were: MPA/ASAO 1.09 ± 0.1 (0.78–1.54); MPA/DESAO 1.36 ± 0.2 (1.0–1.89). When compared to the MPA and MPA/ASAO values reported in the nonpregnant population, 24.5% of pregnant women had an MPA diameter above the upper limit of normal and 85.7% MPA/ASAO above 1.0. There were no significant differences in MPA or MPA/ASAO between the 3 trimesters.
The devastating consequences and the high mortality associated with a diagnosis of PHT in pregnancy justify the development of normal range of PA size in pregnancy is important. In the nonpregnant population, a ratio > 1.0 on CT is predictive of pulmonary hypertension. However, in gravidas, this is most likely reflective of the hemodynamic changes of pregnancy. This study is limited by the small number of patients in the first trimester and the lack of pressure correlation. Prospective studies are needed to address this question further.
MPA size is higher in pregnancy than the general population and MPA/ASAO > 1.0 may not be as predictive of pulmonary hypertension as it is in the general population.
Hanan Khalil, No Financial Disclosure Information; No Product/Research Disclosure Information