Adjunct Left Atrial Procedures

LEFT ATRIAL THROMBUS FORMATION

Thrombus formation in the left atrium ( Fig. 16-1 ) is frequently observed in long-lasting rheumatic valvular disease, triggered enlarged left atrium, atrial fibrillation, endocardial lesions, and low cardiac output. In degenerative valvular disease, atrial thrombus formation can be observed in elderly patients or in those with low cardiac output or hematological disorders. Atrial fibrillation is the major contributing factor for atrial thrombus formation in these conditions. Different types of thrombus can be observed :

• Left atrial appendage thrombus is the most common location (a) . The thrombus is usually organized and adherent to the endothelium. It should be completely removed before closing the orifice of the atrial appendage. The absence of an intraoperative visible thrombus does not preclude the existence of thrombus formation during the course of the disease, in particular in the presence of a large appendage, an irregular endocardial surface, or a history of stroke. In these circumstances, the left atrial appendage should also be closed. The closure of the left atrial appendage is performed in most instances by endoatrial direct suturing. This technique is preferred to external ligation, which may not completely occlude the base of the appendage, a cause of recurrent thrombus formation. Whenever the orifice of the atrial appendage is calcified, the closure is carried out using a pericardial patch.

• Extended thrombus covering a large surface of the left atrium can be approached using different techniques. Whenever the thrombus can be separated easily from the left atrial wall, it should be removed, excising occasional endothelial bands. Whenever the thrombus cannot be separated easily, it can be left in place provided that its surface is regular. Whenever an irregular surface with or without ulcerations or spots of calcification is present, the thrombus should be removed en bloc . This thromboendocardiectomy may leave areas of thin atrial tissue or a block of calcification, which should be covered by a large pericardial patch ( Fig. 16-2 ).