**2. Etiology**

AS without accompanying mitral valve disease is more common in men than in women [2] and rheumatic etiology is currently rare. Age-related degenerative calcific AS is currently the most common cause of AS in adults and the most frequent reason for aortic valve re‐ placement (AVR) in patients with AS. Sclerosis of the aortic valve is observed in up to 30%

© 2013 Leal et al.; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2013 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

of elderly people: 25% of people aged 65 to 74, and 48% of people older than 84 years [3,4]. This calcific disease progresses from the base of the cusps to the leaflets, eventually causing a reduction in leaflet motion and effective valve area without commissural fusion. Calcific AS is an active disease process characterized by lipid accumulation, inflammation, and calci‐ fication, with many similarities to atherosclerosis. In approximately half of cases there is a bicuspid aortic valve basis. Bicuspid aortic valve valvulopathy affects 2% of the population, making it the most frequent congenital anomaly, representing the more common cause among young adults [5].

tance in assessing annulus diameter before TAVI and in guiding the procedure. Intraproce‐ dural TOE enables us to monitor the results of percutaneous procedures [11]. Threedimensional TOE offers a more detailed examination of valve anatomy than twodimensional echocardiography and is useful for the assessment of complex valve problems or for monitoring surgery and percutaneous intervention [11]. Three-dimensional echocar‐ diography (3DE) is useful for assessing anatomical features which may have an impact on the type of intervention chosen, if it is needed. AS severity could be graded on the basis of a variety of hemodynamic and natural history data, using definitions of aortic jet velocity,

New Therapeutic Approaches to Conventional Surgery for Aortic Stenosis in High-Risk Patients

http://dx.doi.org/10.5772/54333

453

Based on the European Society of Cardiology (ESC) Guidelines on the management of valv‐ ular heart disease [12], American College of Cardiology/American Heart Association (ACC/ AHA) Guidelines for the Management of Patients With valvular heart disease [10] and ASE/EAE Recommendations for Quantitation of Stenosis Severity, [13] ACC/AHA guide‐ lines use lower mean gradient cutoffs as indicated in parentheses. The ESC definitions apply only in the presence of normal flow conditions. The velocity ratio is included in the

Multi-slice computed tomography (MSCT) and cardiac magnetic resonance (CMR) provide additional information on the assessment of the ascending aorta when it is enlarged. MSCT may be useful in quantifying the valve area and coronary calcification, which aids in assess‐ ing prognosis. MSCT may contribute to the evaluation of the severity of valve disease, par‐ ticularly in AS, either indirectly by quantifying valvular calcification, or directly through the measurement of valve planimetry. Also, MSCT has become an important diagnostic tool for evaluation of the aortic root, the distribution of calcium, the number of leaflets, the ascend‐ ing aorta, and peripheral artery pathology and dimensions before undertaking TAVI [11]. In patients with inadequate echocardiographic quality or discrepant results, CMR should be used to assess the severity of valvular lesions—particularly regurgitant lesions—and to as‐ sess ventricular volumes and systolic function, as CMR assesses these parameters with high‐ er reproducibility than echocardiography [11]. In practice, the routine use of CMR is limited because of its limited availability, compared with echocardiography. Due to its high nega‐ tive predictive value, MSCT may be useful in excluding CAD in patients who are at low risk

**Aortic Stenosis**

mean pressure gradient, valve area and velocity ratio as shown in Table 1.

*Indicator Mild Moderate Severe* Aortic jet velocity (m/s) 2.6-3 3-4 ≥4 Mean gradient (mmHg) ≤30(25) 30-50(25-40) ≥50(40) Indexed AVA (cm2/m2) ≥0.9 0.6-0.9 ≤0.6 AVA (cm2) ≥1.5 1-1.5 ≤1 Velocity ratio ≥0.50 0.25-0.50 ≤0.25

**Table 1.** Classification of the Severity of Aortic Valve Disease in Adults

ASE/EAE guidelines only.
