This chapter discusses the surgical indications, operative techniques, and early and late follow-up after implantation of mechanical and bioprosthetic mitral valve devices. The valves that are discussed are those that are currently (2015) approved by the Food and Drug Administration (FDA). Figure 42-1 shows the former and current FDA-approved prosthetic mechanical mitral valve devices, including the Starr-Edwards ball-and-cage valve (historical relevance only), the Omnicarbon tilting-disk valve, the Medtronic Hall tilting-disk valve, the St. Jude Medical bileaflet valve, the Carbomedics bileaflet valve, the ATS bileaflet valve, and the On-X bileaflet valve. The FDA-approved bioprosthetic valve devices are shown in Fig. 42-2 and include the Hancock II porcine valve, the Carpentier-Edwards porcine valve, the Carpentier-Edwards pericardial valve, the Mosaic porcine valve, and the Biocor porcine valve.
FDA-approved mechanical mitral valves. (A) Starr-Edwards ball-and-cage. (B) Medtronic Hall tilting-disk. (C) Omnicarbon tilting-disk. (D) St. Jude Medical bifleaflet. (E) Carbomedics bileaflet. (F) ATS bileaflet. (G) On-X bileaflet.
FDA-approved bioprosthetic mitral valves. (A) Hancock II porcine heterograft. (B) Carpentier-Edwards standard porcine heterograft. (C) Mosaic porcine heterograft. (D) Carpentier-Edwards pericardial bovine heterograft. (E) St. Jude Biocor porcine heterograft.
Heart valve prostheses are continually undergoing iterative advancement by the manufacturers; however, the ideal valve has yet to be developed. This ideal replacement prosthesis would have longevity of a mechanical prosthesis combined with the superior hemodynamic function of the native biologic tissue valve. As a result, this hypothetical ideal replacement device would not require lifetime anticoagulation and carries no risk of either thromboembolic events or valve thrombosis. Achieving this goal will require major advancements to currently available designs.
INDICATIONS FOR MITRAL VALVE REPLACEMENT
The indications for mitral valve replacement (MVR) are variable and undergoing evolution. Because of increasing use of reparative techniques, particularly for mitral regurgitation (MR), replacement or repair of a mitral valve often depends on the experience of the operating surgeon. Current indications for valve replacement pertain to the types of valve problems that are unlikely to be repaired by most surgeons or which have been shown to have poor long-term success after reconstruction. Indications are discussed according to (1) pathophysiologic states and (2) type of valve required (ie, mechanical or bioprosthetic).
Mitral stenosis (MS) is almost exclusively caused by rheumatic fever even though a definite clinical history can be obtained in only about 50% of patients. The incidence of MS has decreased substantially in the United States in the last several decades because of effective prophylaxis of rheumatic fever; nevertheless, in certain developing countries MS is still very common. Two-thirds of patients with rheumatic MS are females.