Pulmonary hypertension (PH) is defined as an increase in mean pulmonary arterial pressure (mPAP) ≥20 mm Hg at rest as assessed by right cardiac catheterization (RCC).1, 2, 3 Its incidence ranges from 2.0 to 7.6 cases per million adults per year, and its prevalence ranges from 11 to 26 cases per million adults.4 Long-term survival in patients with HAP has improved significantly over the past 2 decades, with a median survival now of 6 years, compared to 2.8 years in the 1980s.5

The clinical classification of PH by World Health Organization (WHO) categorizes multiple clinical conditions into 5 groups according to their clinical presentation, pathological findings, hemodynamic characteristics, and treatment strategy.1,6, 7, 8, 9 Group 1 includes pulmonary arterial hypertension (PAH), which is defined as precapillary PH; it means an mPAP greater than or equal to 20 mm Hg, pulmonary artery wedged pressure (PAWP) less than or equal to 15 mm Hg, and pulmonary vascular resistance (PVR) greater than 3 Wood units.2,7,9,10

Exertion usually induces initial symptoms, including dyspnea, fatigue, weakness, angina, and syncope.1,2,11 In diagnostic imaging, the presence in computed tomography pulmonary angiography (CTPA) of dilatation of the right ventricle (RV), dilatation of the right atrium, enlargement of the main pulmonary artery (diameter >29 mm), or a relationship between the diameter of the main pulmonary artery/ascending aorta >1, are signs suggestive of PH.3,11,12 The RHC is the gold standard for diagnosis, a low-risk outpatient procedure that, when performed in expert centers, has a mortality rate of less than 0.1%. Since the diagnosis of HAP is determined by the hemodynamic measurements obtained during the RHC, the quality, and accuracy of these measurements are of paramount importance.1,2,6,13

Pulmonary artery aneurysms (PAA) and pulmonary trunk aneurysms are rare, underdiagnosed entities that involve life-threatening conditions. An aneurysm is the focal dilation of a blood vessel involving all three layers of the vessel wall.14, 15, 16 The causes can be congenital or acquired; these include vasculitis, infections, neoplasia, and trauma, often iatrogenic. Isolated idiopathic aneurysms are infrequent entities.14,15,17,18

PAAs can be classified into proximal (or central) and peripheral. Proximal PAAs involve the pulmonary trunk and the right and left major PAs. Proximal PAAs are defined as a diameter greater than 4 cm measured in the trunk of the pulmonary artery (PA).14, 15, 16 Peripheral PAAs encompass aneurysms located in the intrapulmonary arteries.14,17 Figure 1 shows examples of proximal PAAs, with the diameter of the trunk of the PA greater than 4 cm measured with CTPA.

The clinical manifestations of PAA are primarily nonspecific, and most patients remain undiagnosed, even those with large PAA, due to its silent course.15 Likewise, cardiac and vascular anomalies and pulmonary hypertension are among the most common.16 When clinical symptoms are present, they vary and are related to the PAA's underlying etiologies, location, and size. The clinical manifestations rarely occur unless there are complications such as bronchial or tracheal compression (leading to cough and dyspnea), dissection, or rupture (leading to hemoptysis).14

CTPA is an excellent diagnostic modality, as it can demonstrate the presence of PAA, permeable lumen, and any mural thrombus or other vessel wall abnormalities.14 Pulmonary arterial hypertension (PAH) is a significant cause of the development of PAA in some patients.15,19 Elevated PA pressures often lead to enlargement of the pulmonary vessels and right heart chambers; progressive dilation of PA may result in PAA.20 PAH is observed in 66% of patients with PAA. PA dissections are usually associated with PAH; 80% of dissections occurred in the main pulmonary trunk.15

Patients with PAA that coexists with PAH should be treated with medical therapy to decrease the pressure of the PA, especially if they do not experience associated symptoms and have aneurysms <6 cm. Although there is no clear guideline for the best treatment of PAA, surgery is indicated in patients with a pulmonary trunk aneurysm >5.5 cm. However, PAH patients with very high surgical risk can be challenging to have surgery.14

In a Spanish study by Nuche et al.20 34% of PAA was observed in patients with PAH. It was detected more frequently in patients with PAH secondary to etiologies associated with a more extended follow-up period, such as PAH related to congenital heart disease. Despite adequate treatment optimization, a significant increase in PA was observed. The authors comment that the time of evolution of PAH was identified as an independent risk factor for the development of PAA. At the same time, no association was found with the hemodynamic severity of PAH at the time of diagnosis of PAH.20

Recent studies found that after diagnosing PAH, most patients during follow-up had progressive dilation of the PA, which was not related to changes in pressure at the hemodynamic level. Even those patients with decreased PA pressure at follow-up were found to have dilated PA.21,22

It has been observed that patients in the PAH group associated with congenital heart disease tend to develop PAA more commonly. Those with PAH associated with connective tissue disease have a smaller diameter of PA dilation. In the same study, patients with PAA had an increased risk of complications, worse survival, and unexplained death.23,24

It is essential to determine the prevalence of PAA in patients with pulmonary hypertension and its association with hemodynamic severity because these patients depend on treatment with specific therapy. However, despite adequate management in these patients, a pulmonary artery aneurysm is observed, which can lead to other symptoms or the development of severe conditions such as hemoptysis, dissection, or rupture of a pulmonary aneurysm.

In a retrospective study of the Arterial Hypertension clinic of our hospital, patients with Pulmonary Arterial Hypertension were included from 2016 to 2021. The diagnosis of PAH was determined according to 2018 standards, defined as mPAP >20 mm Hg, PEAP >15 mm Hg, and PVR > 3UW.6 The selection of patients also considered that they had chest CT angiography and hemodynamic determination of complete RHC. The measurement of the diameter of the PA was made at the tomographic level of the bifurcation of the same, taking the largest diameter at the perpendicular level of the long axis, at least one centimeter above the bifurcation, considering PAA to the diameter >40 mm. Clinical and laboratory variables were obtained from medical records in the record.