Contrast Echocardiography in Patent Foramen Ovale

Abstract

Contrast echocardiography has been shown to be a very sensitive method for the diagnosis of hemodynamically significant interatrial communications (atrial septal defect). Shunting of contrast echoes from the right to the left heart can be detected by either M-mode [1, 2] or cross-sectional [3–5] contrast echocardiography in most patients with atrial septal defect even in the absence of Eisenmenger’s reaction and cyanosis. The demonstration of atrial, left-to-right shunts requires the use of two-dimensional echocardiography. With this method the left-to-right shunt is seen during right atrial opacifications as a “negative contrast” effect at the site of the defect [6, 7]. The ability to detect right-to-left or left-to-right shunting is largely independent of the size of the atrial septal defect [1–3, 5–8]. We have therefore investigated if very small, hemodynamically insignificant interatrial communications could also lead to the same contrast echocardiographic phenomena. The occurrence of positive contrast studies in patients with only a patent foramen ovale would have important consequences for the diagnosis of atrial septal defect by contrast echocardiography; and furthermore the noninvasive detection of a patent foramen ovale may sometimes be clinically important, for example, in patients with unexplained cyanosis or in suspected paradoxical embolism.