Hemodynamic evaluation of small-size aortic prostheses

Abstract

Surgeons are presently able to choose from a variety of satisfactory valve prostheses, depending on the individual situation. The durability, thromboembolic potential, and hemodynamic properties of any valve must be balanced against specific anatomic and clinical factors. Thus, if a surgeon is most concerned about durability, he might choose the bare strut Starr-Edwards ball valve or the Smeloff-Cutter valve, the most proven valves by length of service. However, the Bjork-Shiley, Lillehei-Kaster, and Hancock valves all have good durability records to seven years.Thromboembolic potential is markedly decreased with tissue valves such as the Hancock porcine xenograft, Carpentier-Edwards porcine xenograft, Ionescu-Shiley pericardial valve, or dura mater valve. Patients with these valves do not usually require chronic anticoagulation, which is associated with significant morbidity and mortality. In clinical situations that contraindicate long-term anticoagulation or when the threat of thromboembolism or bleeding is very high, the use of a tissue valve is particularly indicated.Hemodynamic considerations may be paramount in some patients with restrictive anatomy; the small diameter, tilting disc valves have the best hemodynamic performance, although new modifications in the Hancock porcine heterograft may reduce the hemodynamic obstruction in these small diameter valves and allow their implantation without long-term anticoagulation.A number of durable and effective devices exist today for valve replacement, and the type of valve used can be individualized according to the valve characteristics, clinical indications, and anatomic considerations.