The Role of Imaging in Aortic Valve Disease

Abstract

Purpose of review: Aortic valve disease is the most common form of heart valve disease in developed countries. Imaging remains central to the diagnosis and risk stratification of patients with both aortic stenosis and regurgitation and has traditionally been performed with echocardiography. Indeed, echocardiography remains the cornerstone of aortic valve imaging as it is cheap, widely available and provides critical information concerning valve hemodynamics and ventricular function.

Recent findings: Whilst diagnostic in the vast majority of patients, echocardiography has certain limitations including operator variability, potential for measurement errors and internal inconsistencies in severity grading. In particular, low-gradient severe aortic stenosis is common and challenging to diagnose. Aortic valve imaging may therefore be improved with alternative and complimentary multimodality approaches.

Summary: This review investigates established and novel techniques for imaging both the aortic valve and the myocardial remodelling response including echocardiography, computed tomography, cardiovascular magnetic resonance and positron emission tomography. Moreover, we examine how the complementary information provided by each modality may be used in both future clinical practice and the research arena.

Keywords: Computed tomography; Echocardiography; Magnetic resonance imaging; Positron emission tomography; Regurgitation; Stenosis; Valve.

Fig. 1

Echocardiographic assessment of a patient with severe aortic stenosis. a Short axis view showing heavily calcified leaflets. b Parasternal long axis view showing large calcium deposit on right coronary cusp with restricted valve opening. c Right sternal edge continuous-wave Doppler with aortic valve velocity >4 m/s, corresponding with severe stenosis

Fig. 2

Survival of patients with aortic stenosis under medical treatment according to valvular calcium score. Patients with severe absolute calcification (a) or calcification indexed to body surface area (b) had increased all-cause mortality compared to patients with non-severe calcification. Indeed, severe aortic valve calcification (AVC) was an independent predictor of survival following adjustment for age, sex, presence of coronary artery disease or diabetes, indexed aortic valve area and ejection fraction. Reproduced from Clavel et al. [••] with permission from Elsevier/Journal of the American College of Cardiology

Fig. 3

18F-fluoride PET activity predicts the development of new calcific deposits in the aortic valve on repeat CT imaging performed after 1 year. Example imaging from two patients (a and b) are shown below. Baseline non-contrast CT images (left) showed evidence of increased 18F-Fluoride PET activity (middle) in areas where subsequent calcification was observed on repeat CT scanning after 1 year (right). Reproduced from Pawade et al. [3] with permission from Elsevier/Journal of the American College of Cardiology

Fig. 4

Cardiac magnetic resonance imaging in a patient with severe aortic stenosis. Predominant asymmetrical hypertrophy of the anteroseptum is seen with associated patchy mid-wall late gadolinium enhancement (LGE, red arrows). These areas are also identified visually using native and post-contrast T1 maps (white arrows)

Fig. 5

Phase-contrast velocity mapping for aortic regurgitation quantification. The slice location for through plane measurement is shown on a three chamber still image (top) with a jet of aortic regurgitation visible (white arrow). Through plane images are shown (middle) in systole depicting magnitude (left) and flow (middle) and diastole showing regurgitation in black (right). Regurgitant volume and fraction can then be calculated from a time-flow curve (bottom). LV left ventricle, Ao aorta, LA left atrium. Reproduced from Myerson et al. [••] with permission from Wolters Kluwer Health, Inc./Circulation