**4. Overview of procedure**

Warfarin is also the drug of choice in patients with AVR with mechanical prostheses. To date there is no alternative for warfarin for these patients and a higher international normalized ratio (2.5-3.5) is targeted. This translates into increased risk of bleeding associated with warfarin especially in the older patients. These patients may also have other bleeding risk factors like concurrent anti-platelet, SSRI or ginkgo biloba use and platelet dysfunction associated with KI or significant AS. Whether warfarin treatment is appropriate for the patient, may even determine if AVR might be performed and if a mechanical prosthesis might be used. Patients, in whom warfarin treatment is planned, should also be carefully assessed about the risk of falls which may lead to significant bleeding, most importantly to intracranial hemor‐ rhage. If warfarin is started, ensuring precautions by educating the patients and their relatives

Surgical AVR is currently the gold-standard treatment for patients with severe symptomatic AS. Without surgery, the prognosis is extremely poor, with a 3-year survival rate of <30%.How‐ ever, in the huge Euro Heart multinational registry in Europe, 33% of symptomatic patients over the age of 65 years were not referred for surgery [60]. The reasons for not planning surgery were not always the co morbidities. David Bach's series showed the same issue and 33% of symptomatic patients were not referred for surgery, some of whom had a low Euro Score risk [61]. Balloon aortic valvuloplasty, which was described in the 1980s, was the first alternative to surgical therapy [62]. Despite high rates of initial procedural success, restenosis is frequently encountered in the long term. The procedure has generally been abandoned in adult patients except as a palliative procedure often prior to surgical AVR [63]. Trans-catheter aortic valve implantation (TAVI) was first described by Andersen et al in 1992 [64]. They implanted an expandable aortic valve by a catheter technique in a closed chest pig model. The first attempt to use TAVI in man was in 2002 by Cribier et al [65]. A percutaneous bioprosthesis was successfully implanted within the diseased native aortic valve through an antegrade trans‐ septal approach. In more recent years, the technology has developed very rapidly and, to date, more than 40,000 transcathater valves have been implanted worldwide. The results of several large multicenter registries and randomized Placement of Aortic Transcathater Valves (PARTNER) trial, TAVI is now the standard of care for extremely high risk or 'inoperable ' patients and is a valid alternative to surgery for selected high-risk but ' operable ' patients

Patients might be considered candidates for TAVI if they fulfill the following criteria: symp‐ tomatic severe AS, a life expectancy of >1year, contraindications for surgery, high risk for surgery (clinical judgment plus Euro Score (logistic) >20%; STS Score>10%), and/or porcelain aorta, history of thoracic irradiation, severe thoracic deformity, patent coronary bypass,

Contraindications for TAVI are as follows: an aortic annulus of <18 mm or >27 mm, bicuspid valves or unicuspid or noncalcified valve, severe aortic regurgitation or mitral regurgitation,

cachexia, recurrent pulmonary emboli, right ventricular insufficiency and cirrhosis.

to avoid falls is also crucial.

390 Calcific Aortic Valve Disease

with symptomatic AS [66-68].

**3. Transcathater aortic valve implantation**

#### **4.1. Approaches used for TAVI**

Stented valves placed either transapically or percutaneously are garnering much attention. In the percutaneous approach, the valve is deployed either antegradely via the transseptal route,or retrogradely across the native aortic valve.

Transfemoral Approach: The transfemoral approach is simper and quick to access the aortic valve. This route is the first choice of approach in the vast majority of centers performing TAVI procedures. Although surgical cutdown was the technique used for the transfemoral approach at the beginning of the TAVI experience, most centers are now using a fully percutaneous technique. The aortic valve is corossed and a stiff wire is placed in the LV with a large loop. Within these procedures, firstly balloon aortic valvotomy is undertaken and a stented bio‐ prosthesis is then deployed over a balloon intothe aortic annulus. Inflation of the balloon anchors the valve in place in the annulus,effectively achieving AVR. Some specific contrain‐ dications for transfemoral approach are; narrow peripheral arteries (diameter < 8-9 mm), severe tortuousity or calcification, history of aorto-femoral by pass, aneurysm of abdominal aorta with thrombosis, and severe atheroma of the arch.

Transapical approach: Transapical approach necessitates a thoracotomy but the valve is deployed into the beating heart and extracorporeal circulation is not performed. This approach is particularly suited to patients with severe peripheral artery disease and heavily calcified ascending aorta and arch. The transapical approach includes the following other benefit: no stored tension in the delivery system, more reliable device control and feedback and no size limitations. The main disadvanteges are the need for thoracotomy; a greater degree of myocardial injury and the potentially life threating bleeding complications associated with the surgical repair.

Subclavian Approach: A subclavian approach allows patient with unfavorable iliofemoral artery anatomy or extensive disease to be treated with TAVI. A surgical cutdown is needed to isolate the subclavian artery. However no specific complications for subclavian access reported, any injury of the subclavian artery would translate into a major intrathoracic bleeding that might be difficult control.

Transaortic approach: In 2009 and 2010, transaortic approach with direct access to the ascend‐ ing aorta though an anterior minithorocatomy has been advocated. Altough requiring sternotomy, avoidance of LV apical injury and avoidance of the use of large cathaters are potential advantages of this novel approach.

#### **4.2. TAVI systems and placement**

Currently two valve systems are approved for TAVI: the balloon expandable Edwards valvethe first generation Cribier-Edwards, second generation Edwards SAPİEN, and the third generation Edwards SAPIEN XT versions and the self expandable CoreValve (Medtronic CV) system.

The EdwardsSAPİEN System consists of a trileaflet pericardial bovine valve mounted in a stainless steel,and it is available in three sizes: 23 mm, 26 mm and 29 mm for transfemoral, transapical and subclavian approaches [Fig1]. The third generation SAPİEN XT calve is available in 20 mm, 23 mm, and 29 mm sizes and is introduced via an 18 F sheath.

The CoreValve ReValving System consist of three porcine pericardial leaflets mounted in a self expandable nitinol frame housed within a percutaneus delivery catheter. This system is available two sizes, 26 mm and 29 mm. The valve is introduced via an 18 F sheath [Fig 2].

Balloon aortic valvuloplasty is systematically performed before valve implantation to facilitate passage of the prosthesis through the stenotic native valve. Although, Grube at al. have suggested direct implantation of the CoreValve system with no prior balloon valvuloplasty [72]. The balloon expandable valve is positioned using fluoroscopy and echocardiography, and ventricular burst pacing is used at balloon inflation to decrease transvalvular flow and avoid expulsion of the system toward the aorta. The self-expandable valve is deployed without burst pacing, by the retracting the outer sheath of the delivery catheter.

**5. Outcomes**

**Figure 2.** The CoreValve ReValving System

**Figure 1.** The EDWARS SAPİEN system

2.3% for conversion to open heart surgery) [73].

Overall, the procedural success rate was >90% in all studies. Valve embolization or conversion to open heart surgery occurred in ~1% of the patients (0.3–3.0% for valve embolization; 0.5–

Current Treatment Options in Aortic Stenosis

http://dx.doi.org/10.5772/54355

393

**Figure 1.** The EDWARS SAPİEN system

dications for transfemoral approach are; narrow peripheral arteries (diameter < 8-9 mm), severe tortuousity or calcification, history of aorto-femoral by pass, aneurysm of abdominal

Transapical approach: Transapical approach necessitates a thoracotomy but the valve is deployed into the beating heart and extracorporeal circulation is not performed. This approach is particularly suited to patients with severe peripheral artery disease and heavily calcified ascending aorta and arch. The transapical approach includes the following other benefit: no stored tension in the delivery system, more reliable device control and feedback and no size limitations. The main disadvanteges are the need for thoracotomy; a greater degree of myocardial injury and the potentially life threating bleeding complications associated with the

Subclavian Approach: A subclavian approach allows patient with unfavorable iliofemoral artery anatomy or extensive disease to be treated with TAVI. A surgical cutdown is needed to isolate the subclavian artery. However no specific complications for subclavian access reported, any injury of the subclavian artery would translate into a major intrathoracic

Transaortic approach: In 2009 and 2010, transaortic approach with direct access to the ascend‐ ing aorta though an anterior minithorocatomy has been advocated. Altough requiring sternotomy, avoidance of LV apical injury and avoidance of the use of large cathaters are

Currently two valve systems are approved for TAVI: the balloon expandable Edwards valvethe first generation Cribier-Edwards, second generation Edwards SAPİEN, and the third generation Edwards SAPIEN XT versions and the self expandable CoreValve (Medtronic CV)

The EdwardsSAPİEN System consists of a trileaflet pericardial bovine valve mounted in a stainless steel,and it is available in three sizes: 23 mm, 26 mm and 29 mm for transfemoral, transapical and subclavian approaches [Fig1]. The third generation SAPİEN XT calve is

The CoreValve ReValving System consist of three porcine pericardial leaflets mounted in a self expandable nitinol frame housed within a percutaneus delivery catheter. This system is available two sizes, 26 mm and 29 mm. The valve is introduced via an 18 F sheath [Fig 2].

Balloon aortic valvuloplasty is systematically performed before valve implantation to facilitate passage of the prosthesis through the stenotic native valve. Although, Grube at al. have suggested direct implantation of the CoreValve system with no prior balloon valvuloplasty [72]. The balloon expandable valve is positioned using fluoroscopy and echocardiography, and ventricular burst pacing is used at balloon inflation to decrease transvalvular flow and avoid expulsion of the system toward the aorta. The self-expandable valve is deployed without

available in 20 mm, 23 mm, and 29 mm sizes and is introduced via an 18 F sheath.

burst pacing, by the retracting the outer sheath of the delivery catheter.

aorta with thrombosis, and severe atheroma of the arch.

surgical repair.

392 Calcific Aortic Valve Disease

system.

bleeding that might be difficult control.

potential advantages of this novel approach.

**4.2. TAVI systems and placement**

**Figure 2.** The CoreValve ReValving System
