Page 100 - Tailoring Electrospinning Techniques for Regenerative Medicine - Marc Simonet

CHAPTER 5
The atrioventricular valves are anatomically and functionally di erent from the semilunar valves, the first being supported by papillary muscles that prevent leaflet prolapse during ventricular contraction. This chapter has its focus on semilunar heart valves.
Heart valve disease causes either insu icient opening (stenosis) or closing (regurgitation) dynamics of the valve, or a combination thereof, which ultimately will result in heart failure. Congenital heart disease a ects 1% of all newborns and o en has its origin in abnormalities of one of the valves or its function.1 A common cause for acquired heart valve disease is rheumatic fever, currently still persisting in developing countries, thereby a ecting children and young adults.2,3 In Industrialized nations, acquired heart valve disease is mainly considered a degenerative pathology, predominantly a ecting the elderly.4,5 In general, heart valve diseases are considered as a worldwide major public health problem causing significant morbidity and mortality. The le -sided valves (aortic valve and mitral valve) are most prone to degenerative dysfunction in adult patients as these are located in the systemic circulation, thereby exposed to harsh hemodynamic conditions. When diagnosed with heart valve disease, the a ected valve can either be repaired or replaced. Despite the existence of an extensive toolbox for valve repair and excellent surgical techniques, 7 out of 10 diseased valves are not suitable to be repaired6
and have to be replaced. With the continuous growth and aging of the world’s population, the social and economic impact of heart valve disease will increase.7 Therewith, the number of patients requiring a heart valve replacement is expected to triple from 290,000 in 2003 to over 850,000 in 2050.8
Nowadays, many valve replacement types are available, mainly classified as mechanical valves or bioprostheses, each having their own advantages or disadvantages.3 Mechanical valves o er excellent structural durability, but are prone to thromboembolic events, thereby committing patients to daily anticoagulation. Bioprostheses are less susceptible to thromboembolic events, but undergo structural valve degeneration which necessitates reoperation. Homogra s, better known as donor valves, represent the most ideal option as to hemodynamic behavior, but these have limited availability. The selection of appropriate heart valve replacement is dependent on patient characteristics, such as patient’s age, lifestyle and tolerance to the use of anticoagulants.9 Although life expectancy is significantly improved by valve replacement, none of the currently available valve prostheses can fully restore native valve function as they lack growth, remodeling and adaptation capacity. Heart valve tissue engineering has the potential to overcome the limitations of today’s valve prostheses by creating an autologous living valve replacement that can grow or adapt to changing functional demands.
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