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

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

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

**4. Analysis of surgical risk and evaluation of life expectancy and quality**

The precise evaluation of surgical risk in a specific patient is not easy and involves an at‐ tempt at individualization based on statistical data from databases containing a large num‐ ber of procedures. The most accepted and validated algorithms that are widely available today are the EuroSCORE, the STS (Society of Thoracic Score) score,and the Parsonnet score. These algorithms predict the surgical risk by assigning weight to various factors that affect the clinical result, but it is clear that they can underestimate or overestimate the risk in cer‐ tain groups of patients who are not represented satisfactorily in the population used to gen‐ erate the algorithm [8]. There is some evidence in the literature of the incorrect prediction of aortic AVR outcome using the EuroSCORE model [9]. The key element for establishing whether patients are at high risk for surgery is multidisciplinary clinical judgment, which should be used in association with a more quantitative assessment, based on the combina‐ tion of several scores (for example, expected mortality >20% with the EuroSCORE and >10% with STS score). This approach allows the team to take into account risk factors that are not covered in scores but often seen in practice, such as chest radiation, previous aortocoronary

presence of significant coronary artery disease (Figure 4).

bypass with patent grafts, porcelain aorta, liver cirrhosis.

**of life**

486 Calcific Aortic Valve Disease

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).


**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 terms, a large artery with dominant elastic elements should have a diameter up to 1 mm smaller than the external diameter of the sheath that has to be introduced for the valve im‐ plantation. Thus, current systems with an external sheath diameter of 28 F (SAPIEN 26 mm, Edwards Lifescience LLC, Irvine, CA), 25 F (SAPIEN 23 mm, Edwards) and 22 F (CoreValve, Medtronic, Inc., Minneapolis, MN) require minimum diameters of 8, 7, and 6 mm, respec‐ tively. Apart from the minimum diameter, the existence of significant vessel tortuosity (>90°), especially when combined with wall calcifications, makes advancing the large sheath problematic, with a high risk of vascular complications that could potentially affect the final outcome. In addition, the existence of extensive circumferential calcifications limits the elas‐ tic dilation of the artery; thus, the minimum diameters referred to above are underestimat‐ ed. Patients who do not meet the criteria of suitable peripheral arterial access may still be candidates for transapical implantation. For the assessment of aortic annulus diameter, we should keep in mind that TTE underestimates its size by a mean of 1.4 mm compared with TEE [6,10], while the latter method also underestimates the size by 1.2 mm compared with intraoperative measurement [10]. Therefore, in order to avoid undesirable and often cata‐ strophic displacement of the prosthesis, there should be a margin of at least 1-2 mm between the diameter of the valve and the size of the aortic annulus estimated using TEE, so that the former may be successfully and safely anchored within the latter. Computed tomography scan aortography and angiography of the ascending aorta are the most appropriate exami‐ nations for investigating these aspects. Those examinations will also be used for the meas‐ urement of the dimensions of the ascending aorta and the aortic arch, which are essential for checking eligibility for the CoreValve (the most important being the diameter of the ascend‐ ing aorta, which should be <4.3 cm) (Figure 5).

**Figure 6.** Three-dimensional reconstruction of contrast-enhanced CT angiography to assess morphology of femoral

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On the basis of first results from clinical trials, CoreValve Revalving System and Edwards Lifescience SAPIEN obtained CE mark approval in 2007 with the specification that these valves are intended for patients with a high or prohibitive risk for surgical valve replace‐ ment or who cannot undergo AVR. The first generation balloon-expandable valve was enti‐ tled Cribier-Edwards valve (Edwards Lifesciences), whereas at present the Edwards SAPIEN valve (Edwards) is commercially available (Figure 7). The Edwards Lifesciences SAPIEN THV device is a balloon-expandable valve. It consists of bovine pericardium that is firmly mounted within a tubular, slotted, stainless steel balloon-expandable stent. Two valve sizes have been developed (23mm and 26mm). At present, available prosthesis sizes are 23 and 26 mm for aortic annulus diameters between 18–22 mm and 21–25 mm, respec‐ tively. The CoreValve Revalving device is a self-expanding frame-valve prosthesis (Figure 7). It consists of a porcine pericardial tissue valve that is mounted and sutured in a multile‐ vel self-expanding nitinol frame. It is available in 26, 29 and 31 mm sizes. The device has a broader upper segment (outflow aspect), which yields proper orientation to the blood flow. The first-generation valve used bovine pericardial tissue and was constrained within a 25 French (F) delivery catheter. The second-generation valve was built with porcine pericardial tissue within a 21 F catheter to allow access through smaller-diameter vascular beds. The third-generation of the device features a catheter with a valve delivery sheath size of 18 F

arteries (left) and centerline stretched view (right)

and a follow-on shaft of 12 F.

**6. Different transcatheter aortic valves**

**Figure 5.** ECG-gated CT-scan of a patient with severe aortic valve stenosis and porcelain aorta after radiation exposure

The anatomy of the thoracic aorta (any chance of porcelain aorta) and the abdominal aorta should be studied by some imaging method for the existence of extensive atheromatosis, mural thrombi and aneurysm (Figure 6).

**Figure 6.** Three-dimensional reconstruction of contrast-enhanced CT angiography to assess morphology of femoral arteries (left) and centerline stretched view (right)

### **6. Different transcatheter aortic valves**

terms, a large artery with dominant elastic elements should have a diameter up to 1 mm smaller than the external diameter of the sheath that has to be introduced for the valve im‐ plantation. Thus, current systems with an external sheath diameter of 28 F (SAPIEN 26 mm, Edwards Lifescience LLC, Irvine, CA), 25 F (SAPIEN 23 mm, Edwards) and 22 F (CoreValve, Medtronic, Inc., Minneapolis, MN) require minimum diameters of 8, 7, and 6 mm, respec‐ tively. Apart from the minimum diameter, the existence of significant vessel tortuosity (>90°), especially when combined with wall calcifications, makes advancing the large sheath problematic, with a high risk of vascular complications that could potentially affect the final outcome. In addition, the existence of extensive circumferential calcifications limits the elas‐ tic dilation of the artery; thus, the minimum diameters referred to above are underestimat‐ ed. Patients who do not meet the criteria of suitable peripheral arterial access may still be candidates for transapical implantation. For the assessment of aortic annulus diameter, we should keep in mind that TTE underestimates its size by a mean of 1.4 mm compared with TEE [6,10], while the latter method also underestimates the size by 1.2 mm compared with intraoperative measurement [10]. Therefore, in order to avoid undesirable and often cata‐ strophic displacement of the prosthesis, there should be a margin of at least 1-2 mm between the diameter of the valve and the size of the aortic annulus estimated using TEE, so that the former may be successfully and safely anchored within the latter. Computed tomography scan aortography and angiography of the ascending aorta are the most appropriate exami‐ nations for investigating these aspects. Those examinations will also be used for the meas‐ urement of the dimensions of the ascending aorta and the aortic arch, which are essential for checking eligibility for the CoreValve (the most important being the diameter of the ascend‐

**Figure 5.** ECG-gated CT-scan of a patient with severe aortic valve stenosis and porcelain aorta after radiation exposure

The anatomy of the thoracic aorta (any chance of porcelain aorta) and the abdominal aorta should be studied by some imaging method for the existence of extensive atheromatosis,

ing aorta, which should be <4.3 cm) (Figure 5).

488 Calcific Aortic Valve Disease

mural thrombi and aneurysm (Figure 6).

On the basis of first results from clinical trials, CoreValve Revalving System and Edwards Lifescience SAPIEN obtained CE mark approval in 2007 with the specification that these valves are intended for patients with a high or prohibitive risk for surgical valve replace‐ ment or who cannot undergo AVR. The first generation balloon-expandable valve was enti‐ tled Cribier-Edwards valve (Edwards Lifesciences), whereas at present the Edwards SAPIEN valve (Edwards) is commercially available (Figure 7). The Edwards Lifesciences SAPIEN THV device is a balloon-expandable valve. It consists of bovine pericardium that is firmly mounted within a tubular, slotted, stainless steel balloon-expandable stent. Two valve sizes have been developed (23mm and 26mm). At present, available prosthesis sizes are 23 and 26 mm for aortic annulus diameters between 18–22 mm and 21–25 mm, respec‐ tively. The CoreValve Revalving device is a self-expanding frame-valve prosthesis (Figure 7). It consists of a porcine pericardial tissue valve that is mounted and sutured in a multile‐ vel self-expanding nitinol frame. It is available in 26, 29 and 31 mm sizes. The device has a broader upper segment (outflow aspect), which yields proper orientation to the blood flow. The first-generation valve used bovine pericardial tissue and was constrained within a 25 French (F) delivery catheter. The second-generation valve was built with porcine pericardial tissue within a 21 F catheter to allow access through smaller-diameter vascular beds. The third-generation of the device features a catheter with a valve delivery sheath size of 18 F and a follow-on shaft of 12 F.

**7. Implantation approaches**

trans-axillary access [11].

(Figure 8).

**7.1. The transapical approach**

**Figure 8.** TAVI using the transapical approach

**7.2. The transfemoral approach**

With regard to the delivery systems and their introduction into ascending aorta, two specific pathways have been explored so far: the antegrade pathway, which uses direct transapical access, and the retrograde pathway, which uses either transfemoral or trans-subclavian or

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The main advantages of using transapical procedures are: [1] the feasibility does not rely on the absence of a concomitant peripheral vascular disease or previous aortic surgery; [2] the delivery system seems to be more "steady" and the procedure itself more "straightforward"; and [3] this access potentially reduces the risk of calcium dislodgement due to the passage of a stiff transfemoral device into a diseased aortic arch. A transapical approach can be used in the operating room, in a hybrid room, or in a catheterization laboratory with a patient un‐ der general anesthesia. Regardless of where the transapical approach is done, it is a prereq‐ uisite that high-quality fluoroscopic imaging must be guaranteed. Apical bleeding is very rare, mostly related to patient tissue fragility or to the team learning curve, and represents the most dangerous complication related to transapical access itself. In transapical TAVI, the cardiac apex is prepared through a small left anterolateral mini-thoracotomy using a pursestring or a crossing suture reinforced by pledgets and, after the procedure, a chest tube is routinely inserted into the left pleura with pain releasers injected in the intercostal tissue

The transfemoral approach is used mostly in cardiac catheterization laboratory or a hybrid room. One of the main advantages of this technique is that it allows fully percutaneous im‐ plantation in conscious patients, as long as the peripheral vessels are of an adequate caliber (more than 6mm diameter), there are no very tortuous vessels, and vascular closure devices

**Figure 7.** Profile of the CoreValve Revaving System (A) and Edwards SAPIEN Transcatheter Heart Valve (B)

Newer devices that have first-in-man application include Paniagua (Endoluminal Tech‐ nology Research, Miami, FL), Enable (ATS, Minneapolis, MN), AoTx (Hansen Medical, Mountain View, CA), Perceval (Sorin Group, Arvada, CO), Jena (JenaValve Technology, Wilmington, DE), Lotus Valve (Sadra Medical, Campbell, CA), and Direct Flow percuta‐ neous aortic valve (Direct Flow Medical, Inc., Santa Rosa, CA). TAVI represents a unique challenge for anesthesiologists. As with other invasive procedures, a careful preoperative assessment, appropriate intraoperative monitoring and imaging, meticulous management of hemodynamics, and early treatment of expected side effects and complications is of ut‐ most importance. An unexpected decrease or increase in systemic vascular resistance re‐ sulting in decreased coronary perfusion pressure or acute heart failure by elevated left ventricular end-diastolic pressure should be avoided by maintaining a normotensive blood pressure and heart rate between 60 bpm and 100 bpm. The choice of anesthetic technique, either local anesthesia with mild sedation promoting spontaneous respiration, deep intravenous sedation with insertion of a laryngeal mask, or general anesthesia, var‐ ies among centers and is probably not associated with a significant difference in out‐ come. Post valvuloplasty and implantation, which were done under rapid right ventricular pacing due to reduce left ventricular ejection and cardiac motion, may require some additional inotropic support. Tracheal extubation can usually be done at the end of the procedure. Close postoperative monitoring is necessary, and admission to an inten‐ sive care unit is required. However, at present a retrograde approach through the femo‐ ral artery is used. During the procedure, a balloon valvuloplasty is first done to facilitate passage of the native aortic valve. During rapid right ventricular pacing, the prosthesis is positioned and deployed under fluoroscopy and echocardiographic guidance. Alternative‐ ly, in patients with difficult vascular access because of extensive calcifications or tortuosi‐ ty of the femoral artery or aorta, a transapical approach can be used. After a partial thoracotomy, direct puncture of the apical portion of the left ventricular free wall is done to gain catheter access to the left ventricle and aortic valve. The prosthesis is subsequent‐ ly positioned and deployed, similar to the antegrade approach.
