Rare roentgenologic manifestations of pulmonary edema

Unilateral pulmonary edema (UPE) is an unusual manifestation of pulmonary edema that is frequently confused with other causes of unilateral alveolar and interstitial infiltrates. Until now limited data existed regarding the prevalence, cause, and outcome of patients presenting with cardiogenic UPE. The purpose of this review is to give insights into this rare entity.

In a recent retrospective study, the prevalence of UPE was 2.1% of all cases of cardiogenic pulmonary edema. UPE was right-sided in 89%. All patients with UPE had severe mitral regurgitation. In patients with UPE, blood pressure was significantly lower, whereas noninvasive or invasive ventilation and catecholamines were used more frequently compared with patients with bilateral pulmonary edema. In-hospital mortality was higher for patients with UPE (39 vs. 8% for bilateral pulmonary edema) and UPE was independently related to death (a 6.5-fold higher risk of death). Delayed treatment of UPE could be one of the explanations for this increased mortality.

UPE is not that rare as considered to be and is mostly related to severe organic or functional mitral regurgitation. Probably because of initial misdiagnosis and delayed appropriate treatment, UPE is related to increased mortality. History, absence of signs of infection, and elevated serum cardiac markers such as B-natriuretic peptide may help to differentiate UPE from other diagnoses. The key examination remains bedside transthoracic echocardiography, although transesophageal echocardiography can also provide additional information regarding the severity and mechanism of mitral regurgitation and documentation of the differential pressure between the right and left pulmonary veins.