Role of Contrast-Enhanced Transesophageal Echocardiography for Detection of and Scoring Intrapulmonary Vascular Dilatation

Background: Intrapulmonary vascular dilatations (IVD) are microvascular pulmonary changes mediated by nitric oxide that cause right-to-left shunt and hypoxemia. Contrast-enhanced transthoracic echocardiography (cTTE) is the gold standard diagnostic test for IVD. Objective: To evaluate contrast-enhanced transesophageal echocardiography (cTEE) in the diagnosis and grading of IVD. Methods: A study group (SG) of 63 cirrhotic patients were compared to 20 shunt-free control subjects (CG). Both groups underwent cTEE and cTTE using intravenous injections of agitated saline solution for contrast tests. Patients with patent foramen ovale, when detected, were excluded. Late appearance of microbubbles in the left atrium was diagnostic of pulmonary shunt (positive contrast test) and was graded as trivial, mild, moderate or severe by cTEE. Contrast tests were negative in 7 patients (35%) and trivial in the remaining 13 (65%) in CG, so only contrast grades >= mild were considered to be positive IVD tests in the SG. Gasometric change was expressed as the alveolar-arterial oxygen tension difference (A-aO(2)D) and was considered abnormally high at values > 20 mmHg. Results: SG: positive IVD tests were present in 23 patients (36%) by cTTE and 47 (75%) by cTEE (P < 0.001). These patients showed A-aO(2)D values significantly higher than those with negative IVD tests (P < 0.02) and were directly proportional to the contrast grade. cTEE allowed the diagnosis of IVD in three additional patients with high A-aO(2)D that were not detected by cTTE. Conclusion: cTEE enabled diagnosis of IVD in a greater number of patients with gasometric changes compared to cTTE. The contrast effect grade by cTEE seems to be proportional to IVD magnitude. (Echocardiography 2010;27:1233-1237).