الفهرس 
DEVELOPMENTAL ANATOMY OF THE AORTIC VALVEOnly 14 pages are availabe for public view
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Abstract
A
ortic stenosis is a common valvular heart diseases. It affects nearly 5% of individuals over 75 years of age.
Aortic stenosis may be caused by degenerative calcification, congenital malformations, or rheumatic fever.
Sever symptomatic calcific aortic valve stenosis (AS) is a proven indication for valve replacement according to the current guidelines. Aortic valve replacement (AVR) utilizing the open surgical techniques with the use of cardiopulmonary bypass (CPB) remains the standard of care for symptomatic patients with severe aortic stenosis (AS). Certain patients, however, cannot take advantage of this option due to co-morbidities and/or hemodynamic conditions rendering them at high risk for surgery.
In the EURO HEART Survey, 31.8% of all patients indicated for surgical valve replacement were accordingly rejected. Several risk stratification systems have been developed for perioperative mortality risk assessment. The EuroScore is a widely used, web-based, easy applicable such tool. It includes patient-based, cardiac and operative related factors such as age, sex, renal insufficiency, left ventricular (LV) dysfunction, pulmonary hypertension and peripheral arteriopathy. A logistic EuroScore of 15% designates high risk.
In the year 2002 a novel alternative approach to surgical aortic valve replacement among critically ill patients with severe aortic valve stenosis has been first introduced by
Cribier – the percutaneous aortic valve replacement.
Transcatheter aortic valve implantation (TAVI) has emerged as an alternative treatment for patients with severe AS considered at high surgical risk with promising early and mid-term results. In contrast to surgical replacement, this method forms a much less invasive approach, which therefore may be safely offered for high-risk surgical patients.
TAVI is currently carried out using different approaches; retrograde transfemoral and antegrade transapical, which share the same main principles. Many reports have shown the safety and efficacy of both transfemoral (TF) and transapical (TA) approaches to TAVI. However, a significant number of patients have poor vascular access due to either small size vessels or severe peripheral vascular disease and are only amenable to treatment with the TA approach.
Two independent TAVI systems have gathered data of safety and feasibility in human trials; the Edwards SAPIEN valve (Edwards Lifesciences Corporation, Irvine, CA) and CoreValve ReValving System (CRS, Medtronic, Luxembourgh). The major difference between both systems lies in the expansion mechanism of the stent-mounted valve: balloon-expandable or self-expandable, respectively. The CRS is a self-expandable, biological, nitinol-stent-mounted aortic valve prosthesis which has first been introduced in 2005.5 Since March 2007, this prosthesis became CE-Mark certified and commercially available.
Transcatheter valves are associated with excellent hemodynamic results, usually with concomitant improvements in the patient’s functional status and quality of life; however, minor residual aortic regurgitation occurs in many patients
Periprocedural stroke, vascular and conduction disturbance complications, occurrence of moderate or severe paravalvular aortic regurgitation, relatively high midterm mortality, and valve durability beyond 3 year follow-up are unresolved issues in TAVI
The ‘valve-in-valve’ treatment of surgical prosthesis dysfunction and the treatment of intermediate-risk patients are two of the most-important fields for the development of TAVI in the near future.