Preprocedural CT evaluation of transcatheter aortic valve replacement: what the radiologist needs to know.

Aortic valve stenosis is the most common valvular heart disease in the Western world. When symptomatic, aortic valve stenosis is a debilitating disease with a dismal short-term prognosis, invariably leading to heart failure and death. Elective surgical valve replacement has traditionally been considered the standard of care for symptomatic aortic valve stenosis. However, several studies have identified various subgroups of patients with a significantly elevated risk for surgery-related complications and death. Thus, not every patient is a suitable candidate for surgery. Recent developments in transcatheter-based therapies have provided an alternative therapeutic strategy for the nonsurgical patient population known as transcatheter aortic valve replacement (TAVR) (also called transcatheter aortic valve implantation or percutaneous aortic valve replacement). In TAVR, the native aortic valve is replaced with a bioprosthetic valve via a nonsurgical endovascular, transaortic, or transapical pathway. Nevertheless, several anatomic and technical criteria must be met to safeguard patient eligibility and procedural success. Therefore, noninvasive imaging plays a crucial role in both patient selection and subsequent matching to a specific transcatheter valve size in an effort to ensure accurate prosthesis deployment and minimize peri- and postprocedural complications. The authors review the relevant anatomy of the aortic root, emphasizing the implications of anatomic pitfalls for correct reporting of imaging-derived measurements and important differences between findings obtained with different imaging modalities. They also discuss the evolving role of computed tomography and the role of the radiologist in patient triage in light of current viewpoints regarding patient selection, device size selection, and the preprocedural evaluation of possible access routes. Online supplemental material is available for this article.

Transcatheter aortic valve replacement: postoperative CT findings of Sapien and CoreValve transcatheter heart valves.

Transcatheter aortic valve replacement represents one of the most exciting medical technical developments in recent years, offering a much-needed therapeutic alternative for patients with severe aortic valve stenosis who, due to comorbidities and advanced age, are considered to be inoperable or at high surgical risk. The efficacy of this procedure compared with standard surgical intervention has been properly validated in multicenter randomized controlled trials (PARTNER A and B trials), leading to widespread clinical implementation, with over 50,000 procedures currently being performed worldwide each year. Although much of the attention has rightly focused on the potential role of computed tomography (CT) in the preprocedural assessment of the aortic root and the establishment of imaging-guided valve-sizing algorithms, less is known regarding the postprocedural CT characteristics of transcatheter heart valves (THVs). However, given the increasing worldwide recognition and clinical implementation of these devices, they will no doubt be encountered with increasing frequency in patients referred for thoracic CT, either for postprocedural evaluation of the aortic root or for unrelated reasons. Familiarity with these devices and their CT characteristics will increase diagnostic confidence and the value of the radiology report. The authors describe the physical and imaging properties of the currently commercially available THVs, their normal postprocedural imaging appearances, and potential complications that can be detected at CT. In addition, they discuss the relative strengths and weaknesses of CT and echocardiography in this setting.