**3. Confirming the severity of aortic stenosis**

Actually, TAVI is indicated only for patients with calcified pure or predominant sympto‐ matic AS. The different imaging modalities can assist in the selection process by providing important information on the aortic valve, coronary arteries, and vascular structures. First, the severity of AS should be assessed. Both transthoracic (TTE) and transesophageal (TEE) Doppler echocardiography are the preferred tools (Figure 2).

**Figure 2.** TTE in the assessment of severe AS

ty (Figure 2). The procedure should be offered to patients who have a potential for functional improvement after valve replacement. It is not recommended for patients who

**Figure 1.** Algorithm to determine the treatment options of patients with severe AS (AVA: aortic valve area; TAVI:

Actually, TAVI is indicated only for patients with calcified pure or predominant sympto‐ matic AS. The different imaging modalities can assist in the selection process by providing important information on the aortic valve, coronary arteries, and vascular structures. First,

transcatheter aortic valve implantation)

**3. Confirming the severity of aortic stenosis**

simply refuse surgery on the basis of personal preference.

484 Calcific Aortic Valve Disease

In addition, the exact anatomy of the aortic valve should be assessed. Echocardiography, multislice CT (MSCT), and magnetic resonance imaging (MRI) can all help to distinguish be‐ tween a bicuspid and a tricuspid aortic valve. It is important to point out that implantation of available percutaneous prostheses is contraindicated in the case of a bicuspid aortic valve, because of the risk of incomplete deployment, significant paravalvular regurgitation, and displacement of the prosthesis [6,7] (Figure 3).

**Figure 3.** ECG-gated CT-scan in a patient with severe aortic valve stenosis (the upper right panel shows the isolated calcification of the tricuspid aortic valve)

A severely calcified aortic valve may result in the inability to cross the native valve with the catheter. Bulky leaflets and calcifications on the free edge of the leaflets may increase the risk of occlusion of the coronary ostia during aortic valve implantation. Therefore, the extent and exact location of calcifications should be carefully assessed before the implantation pro‐ cedure. Assessing coronary anatomy is also important in the selection process. Conventional coronary angiography, which remains the "gold standard", should be done to exclude the presence of significant coronary artery disease (Figure 4).

**5. Assessment of feasibility and exclusion of contraindications for TAVI**

Indications for Transcatheter Aortic Valve Implantation

http://dx.doi.org/10.5772/53437

487

After criteria of severe symptomatic aortic valve stenosis and high surgical risk are evaluat‐ ed, the technical evaluation of the patient's suitability for the percutaneous implantation

technique begins (Table 1).

Mild to moderate aortic stenosis

Asymetric heavy valvular calcification

Previous aortofemoral bypass

Coarctation of the aorta

Calcified pericardium

Severe respiratory insufficiency Non-reachable left ventricular apex

Aortic root "/>45mm at the aortotubular junction Presence of left ventricular apical thrombus Contraindication for transfemoral approach

Severe angulation, severe atheroma of the aorta

Previous surgery of the left ventricle using a patch

Contraindication for transapical approach

Aneurysm of the aorta with protruding mural thrombus

Asymptomatic patients Life expectancy <1 year

Bicuspid aortic valve

**Indication for Transcatheter aortic valve implantation**

**Contraindication for Transcatheter aortic valve implantation**

Surgical aortic valve replacement possible, but patient refused

Severe calcification, tortuosity, small diameter of the iliac arteries

**Table 1.** Actually proposed indications and contraindications for TAVI

The two most basic parameters are the suitability of the peripheral arteries and the size of the aortic valve annulus. Contrast angiography is needed to assess the former, while the lat‐ ter requires an initial assessment of the diameter of the aortic annulus on a TTE. In general

Contraindication for surgical valve replacement

Severe aortic stenosis (AVA: <1cm2,mean gradient "/>40mmHg, severe symptoms)

Aortic anulus <18 or "/>25mm (balloon-expandable) and <20 or "/>27mm (self-expandable)

**Figure 4.** Invasive diagnostic prior TAVI, including aortography and access vessels as well as transvalvular gradient
