[Echocardiography in the diagnosis of lung embolism]

In the Federal Republic of Germany, approximately 10,000 to 20,000 persons die of pulmonary embolism (PE) each year. The mortality of treated PE is about 8% as compared with 18 to 35% in nondiagnosed PE. Massive PE is detected in only about 15 to 30% of the patients while, on the other hand, in 30 to 80% of those in whom PE is suspected the pulmonary angiogram may be normal. On use of pulmonary ventilation-perfusion scintigraphy, in 30 to 40% of the cases, both false negative as well as false positive findings have been described. ROLE OF ECHOCARDIOGRAPHY IN PATIENTS WITH ACUTE PULMONARY EMBOLISM. With echocardiographic imaging, the right heart as well as the central vessels in the proximity of the heart, in particular the pulmonary arteries, can be visualized. In addition to direct detection of right-sided-intraluminal thrombi, echocardiographic diagnosis is based predominantly on indirect signs, such as evidence of an acute cor pulmonale with dilatation of the right atrium and ventricle, the central pulmonary vessels and the inferior vena cava which, however, are relatively unspecific and may also be found in the presence of other diseases. Echocardiographic changes in acute pulmonary embolism can only be expected in the presence of increased pressure in the pulmonary circulation, that is, when at least a 30%-reduction in the cross-sectional area of the pulmonary vascular bed can be found. This can be documented in 60 to 70% of patients with acute PE. According to the literature and our own studies, of a total of 284 patients 84% had dilatation of the right ventricle, 70% paradoxic or hypokinetic motion of the interventricular septum in 102/141 patients there was dilatation of the right pulmonary artery. These changes regressed rapidly after therapeutic intervention. In about 30% of the patients a reduction in the left ventricular dimensions can be seen. Paradoxic septum motion and a decrease in the closing amplitude (EF-slope) of the anterior mitral leaflet can be seen. The extent of dilatation of the right ventricle and the right pulmonary artery correlate with the extent of the angiographic severity of acute PE provided that there is no marked preexisting left ventricular function impairment. NONINVASIVE ESTIMATION OF THE PRESSURE INCREASE IN THE PULMONARY CIRCULATION. On use of Doppler echocardiography, most patients with acute cor pulmonale have tricuspid regurgitation. This enables through determination of the systolic RV-RA pressure gradient an estimation of the systolic right ventricular pressure and, accordingly, the pulmonary artery pressure. In our experience, a systolic acceleration time in the pulmonary artery of less than 90 to 95 ms is