Two-dimensional Echocardiographic Assessment of the Idiopathic Hypereosinophilic Syndrome Anatomic Basis of Mitral Regurgitation and Peripheral Embolization

SUMMARY Important cardiac manifestations in the idiopathic hypereosinophilic syndrome include mitral regurgitation and peripheral embolization. To determine the anatomic basis of these abnormalities, real-time, wide-angle, two-dimensional echocardiography (2-D echo) was performed in 21 patients with the hypereosinophilic syndrome. Nine patients (43%) had clinical evidence of mitral regurgitation, and each had localized thickening of the posterobasal left ventricular wall behind the posterior mitral leaflet and absent (seven patients) or diminished (two patients) motion of the posterior leaflet. Anatomic observations at operation or necropsy in four patients with mitral regurgitation demonstrated that the echocardio-graphic abnormalities resulted from posterior mitral leaflet thickening and adherence of the leaflet to the underlying mural endocardium of the posterobasal wall. On 2-D echo, each of the six patients with peripheral emboli had either apical left ventricular echo-dense targets consistent with thrombus or thicken-ing of the posterobasal wall of the left ventricle, and these findings were validated at autopsy or operation in three patients. Hence, in patients with the hypereosinophilic syndrome, 2-D echo is useful in identifying the probable etiology of two important cardiac manifestations. Thickening of the posterobasal wall is usually associated with impairment of posterior mitral leaflet function, resulting in mitral regurgitation. Because the hyper