Aortic valve disease has traditionally been classified on the basis of valve dysfunction: stenosis versus regurgitation. Now, classification is more appropriately based on the underlying pathology because progression and management are (at least partly) determined by disease etiology, not just valve hemodynamics. Thus this chapter first describes the causes of aortic valve disease and then discusses the hemodynamics of valve dysfunction, followed by a summary of clinical outcomes, medical therapy, and timing of surgical intervention.
The prevalence of significant aortic valvular heart disease (moderate severity or worse) increases with age, present in only 0.7% of those age 18 to 44 years but increasing to 13.3% of adults 75 years and older.1 Compared with other types of clinically significant valve disease seen on echocardiography, native aortic valve stenosis was the most common (34%) in the Euro Heart Survey, followed by previous valve surgery (28%), mitral regurgitation (25%), and multivalve disease (20%).2
The normal aortic valve consists of three leaflets suspended in the aortic sinuses of Valsalva. Anatomically, the normal aortic valve has a complex three-dimensional shape, with each cusp consisting of a curved aortic sinus with the semi-cylindrical leaflet attached superiorly at the commissures and inferiorly at the junction with the left ventricular (LV) outflow tract (Fig. 76–1).3,4 The coronary ostia in each sinus give their names to the aortic leaflets: the right coronary cusp, the left coronary cusp, and the noncoronary cusp. In diastole, the leaflets overlap slightly with each other, and there is an area of central thickening at the tip of each leaflet (the nodule of Arantius), which helps to ensure complete valve closure. In systole, the leaflets open passively into a near circular orifice as ventricular contraction results in ejection of blood across the valve into the aorta. Histologically, the layers of the aortic valve leaflet are as follows (Fig. 76–2)5:
- Fibrosa—a dense collagenous layer that provides tensile strength
- Spongiosa—loose connective tissue at the base of the leaflets
- Ventricularis—elastin-rich layer on the ventricular side of the valve
- Endothelium—outer layer on both the aortic and ventricular sides of the leaflet
Normal anatomy of the aortic valve and aortic root. A. Long-axis cut through the aortic root. The aortic valve leaflets are suspended in the aortic sinuses of Valsalva. Each cusp consists of a leaflet attached superiorly at the commissures and inferiorly at the junction with the left ventricular outflow tract. The zone of leaflet coaptation is 1 to 2 mm with an area of central thickening at the tip of each leaflet (nodule of Arantius) to help ensure complete valve closure. B. The anatomic equivalent of a short-axis view of the aortic valve with the noncoronary cusp on top, the right coronary cusp to the bottom (left), and the left coronary cusp to the bottom (right...