Chronic Thromboembolic Occlusion in the Adult Can Mimic Pulmonary Artery Agenesis: Discussion
Cardiac catheterization disclosed pulmonary artery pressure of 90/45 mm Hg (mean: 62 mm Hg); wedge pressure, 9 mm Hg; CO, 5.4 L/min; calculated PVR, 792 dynes^s’cm. Pulmonary angiography disclosed smooth termination of the left pulmonary artery (Fig 8). On the right, there were multiple defects in all lobar branches. The study was believed to be compatible with multiple chronic pulmonary emboli on the right side, and either a large central thrombus or pulmonary agenesis on the left side.
Review of chest x-ray films since 1977 disclosed no evidence of a left pulmonary arterial shadow, oligemia of the left lung, and slightly diminished volume of the left lung with elevation of the left hemidiaphragm.
Pulmonary angioscopy was performed. An organized thrombus was visualized in the left main pulmonary artery, and chronic thrombi were visualized in all lobar branches on the right. The patient underwent a successful bilateral pulmonary thromboendarterectomy.
Pulmonary artery agenesis in children usually does not present a diagnostic problem because of the common association with pulmonary hypertension or other congenital cardiac abnormalities. However, in the absence of such coexisting abnormalities, survivorship to adulthood often occurs without symptoms and, therefore, without discovery. In other instances, dyspnea may be so insidious in onset that the patient may adopt a restricted lifestyle and report minimal symptoms. The experience reported here indicates that, in the adult, differentiation between isolated UPAA and C T-E PH in which one pulmonary artery is completely thrombosed can provide a major challenge in differential diagnosis. Application of even the most sophisticated radiographic imaging techniques may leave the differentiation in doubt. add comment
In over 30 percent of adults with UPAA, the patient is asymptomatic, and an abnormal routine chest radiograph leads to consideration of the diagnosis. In the remainder of the patients, a chest radiograph may be obtained because of unexplained dyspnea on exertion or episodic hemoptysis. Some patients with UPAA come to attention because marked cardiorespiratory symptoms develop with rather modest episodes of pulmonary inflammatory disease (eg, pneumonia) involving the perfused lung. Whatever the basis for the initial chest x-ray films, the classic findings are absence of one central pulmonary artery shadow, relative lucency (lack of vascular markings) in the affected lung, diminution in the volume of that lung (hypoplasia); and the collateral findings of a small lung such as elevation of the hemidiaphragm, narrowed intercostal spaces, mediastinal shift or a rotated cardiac silhouette.
Figure 8. A totally smooth wall along left side of main pulmonary artery gives no evidence of an origin for a left pulmonary artery.