[Pulmonary embolism and thrombi of the right heart].

In general, there are two types of right heart thrombi diagnosed by echocardiography: mobile and non-mobile thrombi, more often located in the atrium than in the ventricle and a potential source of pulmonary embolism. However, they differ in several points: clinical context, clinical and echocardiographic presentations, embolic potential, prognosis and treatment. The result of peripheral venous thrombosis, mobile thrombus it is usually diagnosed during echocardiographic investigation of pulmonary embolism. The appearances are often that of serpentine thrombus floating in the right heart chambers associated with signs of acute cor pulmonale. It is a marker of imminent and often fatal embolism as it completes a previous and usually severe pulmonary embolism; the mortality is over 40%. It is a contra-indication for pulmonary angiography because of the risk of embolism and a therapeutic emergency. Some groups advocate surgical embolectomy and others thrombolysis. Its precise frequency in the acute stage of pulmonary embolism and its treatment remain to be determined by a prospective, multicentre clinical trial. The adherent non-mobile thrombus is usually implanted on the free wall of the right atrium or the interatrial septum. Its formation, in situ, is due to stasis secondary to decompensated congenital or acquired cardiac disease or to the presence of an intracardiac foreign body such as a pacing wire. It is less likely to cause pulmonary embolism. It decreases or disappears with anticoagulant therapy and the outcome is usually good. The differential diagnosis between a mobile thrombus and a Chiari network, or between an adherent thrombus and a vegetation on a intracardiac pacing wire may be difficult and requires transoesophageal echocardiography. The investigation of pulmonary embolism requires systematic echocardiography, one of the objectives of which is to search for right sided thrombi.