BACKGROUND: Intrapulmonary vascular abnormalities result in the right-to-left shunting and severe hypoxemia in liver transplantation candidates. Currently, a convenient, sensitive and effective method is absent to screen the intrapulmonary vascular dilatations.OBJECTIVE: To evaluate the role of contrast-enhanced echocardiography on clinical diagnosis of intrapulmonary shunting in liver transplantation candidates.DESIGN, TIME AND SETTING: The experiment, prospective controlled observation based on cases, was performed at the Hepatology Unit of the 458 Hospital of PLA (Guangzhou, Guangdong, China) from February 2004 to February 2006.PARTICIPANTS: Twenty-four consecutive liver transplantation candidates were recruited from the Hepatology Unit of the 458Hospital of PLA.METHODS: Routine examination was conducted under the condition without any regimen of vascular dilatation drugs.Contrast-enhanced echocardiography was applied to detect the prevalence of right-to-left shunting in the patients with end-stage liver disease. The microvesicle of the left ventricle in patients was qualitatively assessed by a score from 1+ to 3+. Accordingly, all patients were divided into two groups: intrapulmonary shunting and non-intrapulmonary shunting.MAIN OUTCOME MEASURES: The prevalence of right-to-left shunting and clinical characteristics of liver transplantation candidates were determined.RESULTS: Ten (41.7%) of 24 patients with positive contrast-enhanced echocardiography were proved to develop the intrapulmonary right-to-left shunting, including 6 for l+ and 4 for 2+ by left ventricle abnormality, which emerged after 6-10 cardiac cycles of right ventricle abnormality. There were no significant differences in age, gender, arterial blood gas analysis and liver function tests between the two groups (P > 0.05). Echocardiography results demonstrated that, the upper digestive tract hemorrhage,spleen thickness that indicated portal hypertension, pulmonary artery systolic pressure and Tei index were significandy higher in the patients of intrapulmonary shunting than in those of non-intrapulmonary shunting (P<0.05-0.01 ).CONCLUSION: Intrapulmonary vascular dilatation occurs frequently in liver transplantation candidates associated with intrapulmonary shunting but without hypoxemia. Contrast-enhanced echocardiography is a sensitive and non-invasive method for the early diagnosis of intrapulmonary vascular dilatation. The pathogenic cause is portal hypertension. Tel index can be used as an important parameter for evaluating right ventricular function in patients of intrapulmonary vascular dilatation.