Hemodynamic perfor
Hemodynamic performance
All prosthetic valves present some degree of obstruction to forward flow ,some function and prosthetic valves orifice areas are sufficiently low . Caged ball prostheses are the most obstructive valves , while tilting disk valves especially the bileaflet tilting –disk designs, are the least obstructive .
Considerations in valve selection
With all mechanical valve prostheses , life time anticoagulation is necessary to minimize the risk of thromboemblic complications . Bioprostheses have the important advantage that chronic anticoagulant therapy is generally not required but their long term of functions is oftes by degeneration .Bioprostheses are generally used in young woman wishing to become pregnant to avoid chromic anticoagulant , which cross the placental circulation and potentially cause serious problems for the fetus ,in contrast mechanical valves may be preferable in children and young adults .
The most important advantages and disadvantages contemporary valves substitutes are shown in table (1-5)
|
Disadvantages |
Advantages |
Valve type |
|
Thrombogenic |
Durable |
Mechanical |
|
Propensity to deteriorate |
Thromboresistant |
Bioprosthetic |
|
Technically demanding insertion Late tearing |
Near-normal limited availability Hemodynamic Thromboresistant |
Homograft |
