Postoperative Echocardiography of the Aorta

Postsurgical Imaging of the Aortic Root and Aorta

Advances in imaging have raised expectations of improved outcomes for both emergency and elective surgery of the aorta. These advances have allowed early diagnosis and more prompt surgical intervention. Simultaneous with improvements in imaging, improved surgical techniques and postoperative care have enhanced outcomes. As a consequence, more patients are presenting for follow-up care.

For both aortic aneurysms and aortic dissections involving the ascending aorta, the surgeon usually resects the diseased segment and interposes a Dacron graft. Importantly, this approach occasionally does not address diseased segments of the proximal aortic root, arch, or descending aortic segments, which leaves behind a weakened aortic wall because of the effects of the primary disease process. Thus, survivors of the initial repair may remain at considerable risk of future complications, including aneurysmal dilatation and eventual rupture. Consequently, appropriate follow-up requires long-term clinical monitoring and follow-up imaging designed to detect such complications and to allow for timely surgical or percutaneous reintervention. The foundation for such follow-up imaging is adequate baseline imaging that provides a reference for future comparisons of aortic size and appearance. Moreover, baseline imaging will detect technical failures and improper or incomplete repairs that have the potential for subsequent complications.

Common Aortic Surgical Techniques

Boxes 137.1 and 137.2 list some of the more common aortic procedures and some of the alternative or less common procedures. A brief discussion of some of the more common procedures follows. The scope of this chapter does not permit detailed discussion of modifications of standard procedures or of less commonly used techniques.

Interposition Technique

This currently standard technique includes excision of the diseased segment of the native ascending aorta and its replacement with a polyester (Dacron) graft ( Fig. 137.1 ). The proximal anastomotic site is often supracoronary, typically at the sinotubular junction, and the distal anastomotic site is immediately proximal to the brachiocephalic artery. The anastomotic sites are often reinforced with externally placed circumferential strips of Teflon felt (DuPont ).

Composite Grafts

The standard approach for repair of acute type A aortic dissection and aneurysms that involve the aortic root is replacement of the aortic valve, root, and ascending aorta with a composite graft. A composite graft, or conduit, is a synthetic (commonly Dacron) aortic graft that includes a directly attached mechanical valve (less commonly a bioprosthetic valve because currently there is no prefabricated composite with a bioprosthetic valve). With composite graft replacement, the coronary ostia are dissected from the native aorta with a rim of the surrounding aorta (button technique) and reanastomosed individually to the composite graft. In select cases of nonpathologic aortic valves, reimplantation or remodeling procedures have become valve-sparing alternatives. Newer graft designs, such as the Valsalva-design graft, recreate the sinuses of Valsalva and more closely resemble the shape and dimensions of the normal aortic root. ^, This type of graft ( Fig. 137.2 ) theoretically promotes sinus expansion, improves coronary blood flow, and decreases mechanical leaflet stress.